NONRESIDENT

TRAINING
COURSE

Electrician’s Mate
NAVEDTRA 14344

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

 PREFACE
About this course:

This is a self-study course. By studying this course, you can improve your professional/military knowledge,
as well as prepare for the Navywide advancement-in-rate examination. It contains subject matter about day-
to-day occupational knowledge and skill requirements and includes text, tables, and illustrations to help you
understand the information. An additional important feature of this course is its reference to useful
information in other publications. The well-prepared Sailor will take the time to look up the additional
information.

History of the course:

• Apr 1996: Original edition released. Authored by EMC(SW) Scottie Harris.

• Sep 2003: Administrative update released. Errata incorporated. Reviewed by
EMC(SW) Marcelito Sangalang and EMC(SW) Darryl Woodall. No change in technical content.

NAVSUP Logistics Tracking Number

0504-LP-102-2479
 TABLE OF CONTENTS

CHAPTER PAGE

1. Rating Information, General Safety Practices, and Administration ....................... 1-1

2. Electrical Installations............................................................................................ 2-1

3. AC Power Distribution Systems ............................................................................ 3-1

4. Shipboard Lighting................................................................................................. 4-1

5. Electrical Auxiliaries.............................................................................................. 5-1

6. Motor Controllers................................................................................................... 6-1

7. Maintenance and Repair of Rotating Electrical Machinery ................................... 7-1

8. Voltage and Frequency Regulation ........................................................................ 8-1

9. Electrohydraulic Load-Sensing Speed Governors ................................................. 9-1

10. Degaussing ............................................................................................................. 10-1

11. Cathodic Protection................................................................................................ 11-1

12. Visual Landing Aids .............................................................................................. 12-1

13. Engineering Plant Operations, Maintenance, and Inspections ............................... 13-1

14. Engineering Casualty Control ................................................................................ 14-1

APPENDIX

I. Glossary ................................................................................................................. AI-1

II. References Used to Develop this NRTC................................................................ AII-1

III. Electrical Symbols ................................................................................................. AIII-1

INDEX.........................................................................................................................................INDEX-1

ASSIGNMENT QUESTIONS follow Index.

 CREDITS

The illustrations listed below are included through the courtesy of the designated source. Permission to
use these illustrations is gratefully acknowledged. Permission to reproduce illustrations and other
materials in this publication must be obtained from the source.

Source Figures

Woodward Governor Company, 1994 9-1 9-16

9-2 9-17
9-4 9-18
9-5 9-19
9-12 9-20
9-13 9-21
9-14 9-22
9-15 9-23
 CHAPTER 1

RATING INFORMATION, GENERAL SAFETY

PRACTICES, AND ADMINISTRATION

Your knowledge and skill make our modem Navy 12. Identify the use and stages of a counseling
possible. Navy training manuals (TRAMANs) help you session.
develop your technical skills. By learning the 13. Recognize the need for training within the
information in this manual and gaining practical
division, the department and the command.
experience on the job, you will prepare yourself for a
successful and rewarding Navy career. The Navy’s 14. Recognize the purpose of training forms and
training system helps you learn the duties of the next records and identify their use to track and
higher grade in your rating. To advance in rate, you monitor training.
must demonstrate your performance on the job. You
must master the required skills and compete in
Navywide advancement exams for the next higher THE ELECTRICIAN’S
paygrade. MATE RATING

As an Electrician’s Mate (EM) you work with

motors, generators, power and lighting distribution
LEARNING OBJECTIVES systems, and a wide variety of test equipment. Your
training for the EM rates includes electronics and
Upon completion of this chapter, you should be able
electrical theory, fundamentals of motor and generator
to do the following:
operation, alarms, sensors, and other electrical
1. Identify various NECs of the EM rating. equipment. To do your job, you use handtools and
electrical measuring equipment to troubleshoot
2. Recognize the purpose of blueprints and
electrical systems. Also, you use blueprints and
drawings. schematic diagrams to understand the performance of
3. Recognize the basic safety requirements for an electrical circuit.
working with electricity.
The EM rating is a general rating and is not divided
4. Identify the safety procedures to follow when into service ratings. An example of a service rating is
working on or with various tools, equipment, the Gas Turbine Systems Technician (GS). The rating
and machinery. is divided into two service ratings-the GSE, who
maintains the electrical support equipment, and the
5. Identify various sources of information about
GSM, who maintains the mechanical or turbine portion
safety.
of the system.
6. Identify basic first-aid procedures to use on
electrical shock victims. The EM rating is geared to shipboard duties;
therefore, there are EMs on most naval vessels. Ashore,
7. Recognize the purpose of the Navy’s Hearing EMs may work in their rating in a repair facility or as
Conservation and Noise Abatement, Heat an instructor. Sometimes, EMs work outside their rating
Stress, and Hazardous Material programs. in a duty such as shore patrol or recruiting.
8. Identify various warning tags, signs, and plates. The requirements for advancement are outlined in
9. Recognize the purpose for equipment tag-out the Manual of Navy Enlisted Manpower and Personnel
procedures. Classifications and Occupational Standards,
NAVPERS 18068. By meeting these requirements, an
10. Identify the standard organization of
EM assigned to any ship in the fleet is qualified to
engineering departments aboard ship.
perform all assigned duties. Some ships have special
11. Recognize the responsibilities of various equipment, such as complex degaussing systems on
personnel in the engineering department. minesweepers. On this type of equipment, EMs require

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special training. A Navy Enlisted Classification (NEC) SOURCES OF INFORMATION
coding system identifies the personnel who have this
special training. No single publication can give you all the
information you need to perform the duties of your rate.
NAVY ENLISTED CLASSIFICATION You should learn where to look for accurate, up-to-date
CODES (NECs) information on all subjects related to the military
requirements for advancement and the professional
What you can do is indicated by your rate. qualifications of your rating.
However, it does not show any of your special skills
Some of the publications described here change
within or outside your rating. NECs show specific
from time to time. When using any publication that is
qualifications that are not shown by the rate designation.
subject to change or revision, be sure you have the latest
The NEC identifies special qualifications by using a
edition.
four-digit number. The qualification considered the
most important is identified by the first code number. You cannot depend on printed material alone.
The qualification of secondary importance is shown by Much of your learning comes from watching
the second code number. You get NECs by completing experienced personnel and practicing your skills.
special on-the-job training (OJT) or through the
successful completion of a class “C” school. Naval Education and Training Publications

Some of the NECs that maybe assigned to qualified

The Naval Education and Training Program
EMs are as follows:
Management Support Activity (NETPMSA) produces
EM— 4613 IMA Outside Electrical Journeyman TRAMANS and NRTCs. These are used as references
and for advancement purposes. NETPMSA also
EM— 4615 Electric Motor Rewinder
produces the Bibliography for Advancement Study,
EM— 4632 Auxiliaries Electrical System Tech- NAVEDTRA 12052.
nician
Navy Training Manuals
EM— 4666 Minesweeping Electrician

EM— 4668 and 4669 Unrep Electrical Component The TRAMANs will help you gain the knowledge
Maintenanceman you need to do your job and to advance. Some
TRAMANs share general information, and personnel in
EM— 4671 Shipboard Elevator Electronic/Elec- many ratings use them. Others, such as the EM, are
trical System Maintenance Technician specific to a particular rating.
EM— 4672 Steam Catapult Electrician You can tell whether a TRAMAN is the latest
EM— 4673 Lamps Mk III Rast/Hrs Electrical Main- edition by checking the NAVEDTRA number. The
letter following the number is the most recent edition of
tenanceman
the TRAMAN, and it is listed in the Catalog of
EM— 4707 Machinery Systems Console Mainte- Nonresident Training Courses, NAVEDTRA 12061.
nance Technician
Navy Electricity and Electronics
QUALIFICATIONS FOR ADVANCEMENT Training Series

Advancement is important. Many rewards of Navy Personnel in many electrical- and electronic-related
life come through the advancement system. Some Navy ratings use the Navy Electricity and Electronics
rewards are easy to see-more pay, more interesting and Training series (NEWS). NEETS gives beginners
challenging job assignments, and greater respect from fundamental electrical and electronic concepts through
officers and enlisted personnel. Also, you enjoy the a self-study method NEETS material is not oriented to
satisfaction of getting ahead in your chosen Navy career. any specific rating structure.

As an EM, you perform both military and The NEETS series is divided into modules that
professional duties. The military requirements and contain related information organized in traditional
professional qualifications for all ratings of the Navy are paths of instruction. Modules 1 through 20 provide a
listed in NAVPERS 18068. training package within the broad fields of electricity

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and electronics. Module 21 presents general following paragraphs, you will learn about periodicals
information on the fundamental concepts of test that should be of interest to you.
methods and practices. Module 22 gives an
The periodical Deckplate is published by NAVSEA.
introduction into microcomputers.
It has useful articles on all aspects of shipboard
engineering. It supplements and clarifies information
DEPARTMENT OF THE NAVY
contained in the Naval Ship’s Technical Manual and
INFORMATION PROGRAM
presents information on new developments.
REGULATION
The periodical Fathom (surface ship and submarine
The Department of the Navy Information and safety review), published quarterly by the Naval Safety
Personnel Security Program Regulation, OPNAVINST Center, provides accurate and current information on
5510.1, is the basic directive for administering the nautical accident prevention
Information Security Program throughout the
The Electronics information Bulletin (EIB) is
Department of the Navy (DON). The program ensures
published biweekly by NAVSEA. Articles in the EIB
the protection of official DON information that relates
contain advance information on field changes,
to national security. It also provides the necessary
installation techniques, maintenance notes, beneficial
instructions and policy guidance for the DON. The
suggestions, and technical manual distribution. Articles
Standard Organization and Regulations of the U.S.
of lasting interest are included in the Electronics
Navy also contains basic information for the ship’s
Installation and Maintenance Book (EIMB). The
security practices.
EIMB is a single-source reference document of
TECHNICAL MANUALS maintenance and repair policies, installation practices,
and overall electronics equipment and material-
Much of your work is routine; however, you always handling procedures. The EIMB is used to implement
face new problems and need to lookup information to the major policies found in the NSTM, chapter 400.
solve them. The engineering legroom on your ship
should contain a comprehensive technical library. The BLUEPRINTS AND DRAWINGS
books in this library are primarily for the engineer
officer’s use, but you will have occasion to use them. Blueprints are reproduced copies of mechanical,
You can find manufacturers’ technical manuals for most electrical, or other types of technical drawings. Navy
of the equipment in the ship in the legroom library. electrical prints are used by the EM to install, maintain,
These technical manuals are a valuable source of and repair shipboard electrical equipment and systems.
information on maintenance instructions, overhaul To interpret shipboard electrical prints, you must be
instructions, inspection procedures, parts lists, able to recognize the graphic symbols for electrical
illustrations, and diagrams. diagrams and the equipment symbols for electrical
The “encyclopedia” of Navy engineering, Naval wiring. For information on blueprint reading and
Ships’ Technical Manual (NSTM), contains the latest drawings, refer to Blueprint Reading and Sketching,
accepted engineering practices. The NSTM is a NAVEDTRA 10077-F1.
publication of the Naval Sea Systems Command
(NAVSEA). The NSTM provides technical information SAFETY AND THE ELECTRICIAN’S
that helps fleet personnel manage ships, shipboard MATE RATING
machinery, and equipment to achieve optimum
performance and readiness for any assigned mission. The material discussed next stresses the importance
of electrical and general safety precautions. The two
PERIODICALS main purposes of safety are to protect personnel and to
ensure that unwanted equipment operations do not
Periodicals are publications such as magazines and occur. You have the responsibility to recognize unsafe
newsletters published at stated intervals. In the Navy, conditions and to take appropriate actions to correct any
most periodicals serve as training and public relations discrepancies. You must always follow safety
media; that is, they instruct and build morale. precautions when working on equipment or operating
Periodicals explain policy, outline the functions of machinery. Preventing accidents that are avoidable will
various units, discuss current happenings, and help you in the Navy and possibly determine whether or
frequently respond to questions and complaints. In the not you survive.

1-3
 Besides studying the information on safety • Inspect equipment and associated attachments
described throughout this manual, you should read and for damage before using the equipment. Be sure
have knowledge of the information on safety in the the equipment is right for the job.
following publications:
Personnel working around energized electric
• circuits and equipment must obey safety precautions.
Naval Ships’ Technical Manual, chapters 300,
Injury may result from electric shock. Short circuits can
330, 400, and 491
occur by accidentally placing or dropping a metal tool,
• Standard Organization and Regulations of the flashlight case, or other conducting article across an
U. S. Navy, OPNAVINST 3120.32 energized line. These short circuits can cause an arc or
fire, even on low-voltage circuits. Extensive damage to
• Navy Occupational Safety and Health equipment and serious injury to personnel may result.
(NAVOSH) Program Manual for Forces Afloat,
OPNAVINST 5100.19
ELECTRIC SHOCK HAZARDS
• Hearing and Noise Abatement, chapter 18, AND PRECAUTIONS
“Hearing Conservation and Noise Abatement,”
OPNAVINST 5100.23 If you don’t recognize hazardous conditions or take
precautions, you could get an electric shock. You must
• Standard First Aid Training Course, recognize hazardous conditions and take immediate
NAVEDTRA 12081 action to correct any discrepancy noted Plates, posters,
signs, or instructions (fig. 1-1), placed in conspicuous
areas, guide personnel in the safe operation or handling
of equipment, components, systems, or material.
SAFETY RESPONSIBILITIES
Warning signs (red) and caution signs (yellow) are
placed in areas where known hazardous conditions
Safety standards and regulations are for the
exist, or could exist. Hazardous areas include those that
prevention of injury and damage to equipment. You are
are wet, oily, or electrical spaces.
responsible for understanding and following safety
standards and regulations. As an individual, you have a The resistance of the human body is low. Therefore,
responsibility to yourself and to your shipmates to do it can’t be relied on to prevent fatal shock if a person
your part in preventing mishaps. As a petty officer, you comes into contact with voltages of 115 volts or even
need to set a good example. You cannot ignore safety lower. When the skin is damp, body resistance can be
regulations and expect others to follow them. as low as 300 ohms. If the skin is broken, body
resistance can be as low as 100 ohms.
Personnel should always obey the following safety
practices: The following are general guidelines for the effect
of shocks from 60-Hz ac systems:
• Obey all posted operating instructions and safety • 1 milliampere (0.001 A)-Shock is felt.
precautions.
• 10 milliamperes (0.01 A)—A person may be
• Report any unsafe condition or any equipment or
unable to let go.
material you think might be unsafe.
• 100 milliamperes (0.1 A)-Shock may be fatal if
• Warn others of hazards or of their failure to
it lasts for one second or more.
follow safety precautions.
The danger of shock from 450-volt ac ship’s service
• Wear or use approved protective clothing or systems is recognized by shipboard personnel. Yet,
protective equipment. there are reports of personnel receiving a serious shock
• Report any injury or evidence of impaired health from this voltage source. Most shipboard fatalities
caused by electrocution are caused by contact with
that occurs during your work or duty to your
115-volt circuits. Regard all electrical energy as
supervisor.
dangerous. Shipboard conditions are particularly
• Exercise reasonable caution as appropriate to the favorable to severe shock because the body may contact
situation if an emergency or other unforseen the ship’s metal structure and body resistance maybe
hazardous condition occurs. low because of perspiration or damp clothing.

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Figure 1-1.—Safety posters.

1-5
Figure 1-1.—Safety posters—Continued.

1-6
 The following safety practices will help you avoid electric cables; however, do this only in an emergency
receiving an electric shock situation.
• Keep your clothing, hands, and feet dry if • Do not wear a wristwatch, rings, other metal
possible. objects, or loose clothing that could become
• When you work in a wet or damp location, use a caught in live circuits or metal parts.
dry, wooden platform to sit or stand on. • Wear dry shoes and clothing, and ALWAYS wear
• Place rubber matting or other nonconductive a face shield.
material between you and the wood surface. • Tighten the connections of removable test leads
• When you work on exposed electrical on portable meters. When checking live circuits,
equipment, use insulated tools and a nonmetallic NEVER allow the adjacent end of an energized
flashlight. test lead to become unplugged from the meter.

LIVE CIRCUITS • Ensure a person qualified to give

mouth-to-mouth resuscitation and cardiac
The safest practice to follow when you maintain or massage for electric shock is in the immediate
repair electrical and electronic equipment is to area.
de-energized all power supplies. However, there are
times when you can’t do this because de-energizing the • Ensure a person who is knowledgeable of the
circuits isn’t desirable or possible. For example, in an system is standing by to de-energize the
emergency (damage control) condition or when equipment.
de-energizing one or more circuits would seriously
• Tie a rope around the worker’s waist to pull him
affect the operating of vital equipment or jeopardize the
safety of personnel, circuits aren’t de-energized. No or her free if he or she comes in contact with a
work may be done on energized circuits before live circuit.
obtaining the approval of the commanding officer.
• Work with one hand only; wear a rubber glove
When working on live or hot circuits, you must be
supervised and aware of the danger involved. The on the other hand. (Where work permits, wear
precautions you must take to insulate yourself from gloves on both hands.)
ground and to ensure your safety include the following
actions: LEAKAGE CURRENTS
Provide insulating barriers between the work and
the live metal parts. The ungrounded electrical distribution system used
• Provide ample lighting in the immediate area. aboard ship differs from the grounded system used in
shore installations. Never touch one conductor of the
• Cover the surrounding grounded metal with a dry
ungrounded shipboard system, because each
insulating material, such as wood, rubber
conductor and the electrical equipment connected to
matting, canvas, or phenolic. his material must
be dry, free of holes and imbedded metal, and it have an effective capacitance to ground. If you
large enough to give you enough working room. touch the conductor, you will be the electrical current
path between the conductor and the ship’s hull. The
• Coat metallic hand tools with plastisol or cover
higher the capacitance, the greater the current flow will
them with two layers of rubber or vinyl plastic
be for your fixed body resistance. This situation occurs
tape, half-lapped. Insulate the tool handle and
other exposed parts as practical. when one conductor of the ungrounded system is
touched while your body is in contact with the ship’s
NOTE: Refer to Naval Ships’ Technical
hull or other metal enclosures. If your hands are wet or
Manual, chapter 631, for instructions on the use of
plastisol. If you don’t have enough time to apply sweaty, your body resistance is low. When your body
plastisol or tape, cover the tool handles and their resistance is low, the inherent capacitance is enough to
exposed parts with cambric sleeving, synthetic resin cause a FATAL electrical current to pass through your
flexible tubing, or suitable insulation from scraps of body.

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 As you read the following sections on ungrounded physical parts, but are an inherent part of the design of
systems, look at figure 1-2. electrical equipment and cable.
A Perfect Ungrounded System Several factors determine the value of the
capacitance generated between the conductor and
A perfect ungrounded system (fig. 1-2, view A)
ground: the radius of the conductor, the distance
exists under the following conditions:
between the conductor and the bulkhead, the dielectric
• The insulation is perfect on all cables, constant of the material between the two, and the length
switchboards, circuit breakers, generators, and of the cable. Similar capacitance exists between the
load equipment. generator winding and ground and between various
load equipment and ground.
• There aren’t any filter capacitors connected
between ground and the conductors. Ideally, capacitors have an infinite impedance to
direct current; therefore, their presence can’t be detected
• The system equipment or cables don’t have any
by a Megger or insulation resistance test. In addition to
inherent capacitance to ground.
the nonvisible system capacitance, typical shipboard
If these conditions are met, there would be no path electrical systems contain radio frequency interference
for electrical current to flow from any of the system (RFI) filters that contain capacitors connected from the
conductors to ground. conductors to ground. These falters may be apart of the
load equipment, or they may mount separately. To
Look at figure 1-2, view A. Here you can see that
reduce interference to communications equipment,
if a person touches a live conductor while standing on
filters are used.
the deck, no completed path exists for current to flow
from the conductor through the person’s body. No
Look at figure 1-2, view C. If physical contact is
electric shock would occur.
made between cable B and ground current will flow
However, shipboard electrical power distribution from the generator through the person’s body to ground
systems don’t and can’t meet the definition of a and back through the system resistances and
PERFECT ungrounded system. capacitances to cable A. This current flow completes
the electrical circuit back to the generator and presents
Real Ungrounded Systems
a serious shock hazard.
In a shipboard real ungrounded system (fig. 1-2,
view B) additional factors (resistance [R] and Suppose you are using a Megger to check for ground
capacitance [C]) must be considered. Some of these are in this system, and you get a reading of 50,000 ohms
not visible. resistance. You can conclude that no low-resistance
ground exists. However, don’t assume that the system
When combined in parallel, the resistances form the is a perfect ungrounded system without checking the
insulation resistance of the system that is periodically
circuit further. Don’t forget the system capacitance that
measured with a 500-volt dc Megger. Look at figure
exists in parallel with the resistance.
1-2, view B. Here, you can see that there’s a generator
insulation resistance, an electric cable insulation Remember, never touch a live conductor of any
resistance, and a load insulation resistance. The electrical system, grounded or ungrounded. Make
resistors cannot be seen as physical parts, but represent insulation resistance tests to ensure the system will
small current paths through equipment and cable operate properly, not to make the system safe. High
electrical insulation. The higher the resists.rw, the insulation readings in a Megger test do not make the
better the system is insulated; therefore, less current will system safe-nothing does.
flow between the conductor and ground.
Representative values of a large operating system can SHOCK-MOUNTED EQUIPMENT
vary widely, depending on the size of the ship and the
Normally on steel-hulled vessels, grounds are
number of electrical circuits connected.
provided because the metal cases or frames of the
Figure 1-2, view B, also shows the capacitance of equipment are in contact with one another and the
the generator to ground, the capacitance of the vessel’s hull. In some installations grounds are not
distribution cable to ground, and the capacitance of the provided by the mounting arrangements, such as
load equipment to ground. As before, these insulated shock mounts. In this case, a suitable ground
capacitances cannot be seen, since they are not actually connection must be provided.

1-8
Figure 1-2.—DANGEROUS! BEWARE! Shipboard ungrounded electrical distribution systems are DEADLY.

1-9
 CAUTION • Short-circuit the secondary of a current
transformer before you disconnect the meter. An
Before disconnecting a ground strap on extremely high voltage buildup could be fatal to
equipment supported by shock mounts, unwary maintenance personnel.
ensure the equipment is DE-ENERGIZED
• Open the primary of a potential transformer
and a DANGER/RED tag is installed
before you remove the meter to prevent damage
to the primary circuit due to high circulating currents.
If the grounding strap is broken and the
equipment cannot be de-energized, use a • In most installations potential transformer
voltmeter from the equipment to ground to primaries are fused, and the transformer and
ensure that no voltage is present. associated meter can be removed after you pull
the fuses for the transformer. When disconnect-
Maintenance of grounding cables or straps consists ing the transformer and meter leads, avoid con-
of the following preventive procedures: tact with nearby energized leads and terminals.
• Clean all strap-and-clamp type of connectors SAFETY SHORTING PROBE
periodically to ensure that all direct
Before you start working on de-energized circuits
metal-to-metal contacts are free from foreign
that have capacitors installed, you must discharge the
matter.
capacitors with a safety shorting probe (fig. 1-3). When
• Replace any faulty, rusted, or otherwise unfit using a safety shorting probe, first connect the test clip
grounding straps, clamps, connections, or parts to a good ground to make contact. If necessary, scrape
between the equipment and the ship’s hull. the paint off the metal surface. Then hold the safety
shorting probe by the handle and touch the probe end of
• When replacing a grounding strap, clean the the shorting rod to the points to be shorted. The probe
metallic contact surfaces and establish electrical end can be hooked over the part or terminal to provide
continuity between the equipment and the ship’s for a constant connection to ground. Never touch any
hull. Check continuity with an ohmmeter (the metal parts of the shorting probe while grounding
reading must be 1 ohm or less). circuits or components.
• Recheck to ensure the connection is securely It pays to be safe—use the safety shorting probe
fastened with the correct mounting hardware. with care
• If a voltage is present, and the equipment cannot NOTE: Capacitors not electrically connected to the
be de-energized, you must wear electrical rubber chassis ground must have their terminals shorted
gloves and use a rubber mat while replacing the together to discharge them by the use of a shorting probe.
grounding strap.
SWITCHBOARDS AND SWITCHGEARS HAND TOOLS
Safety precautions, operating instructions, wiring Hand tools include all electric-, electronic-,
diagrams, and artificial respiration/ventilation pneumatic-, and hydraulic-powered equipment used in
instructions must be posted near the switchboards and the repair, maintenance, calibration, or testing of other
switchgears. DANGER HIGH VOLTAGE signs must shipboard equipment. Handtools can either be installed
be posted on and/or near switchboards, switchgears, and in a fixed location or portable. You probably have seen
their access doors. some dangerous practices in the use of hand tools that
could have been avoided One unsafe practice involves
SWITCHBOARD METERS AND
the use of handtools with plastic or wooden handles that
INSTRUMENT TRANSFORMERS
are cracked, chipped, splintered, broken, or
When removing or installing switchboard and unserviceable. Do not use these tools.
control panel meters and instrument transformers, you
need to be extremely careful to avoid electric shock to
PORTABLE ELECTRIC-POWERED
yourself and damage to the transformers and meters.
TOOLS
Some of the precautions you should follow when
working around switchboard meters and instrument Portable, electric-powered tools should be clean,
transformers include the following: properly oiled, and in good operating condition. Before

1-10
 Figure 1-3.—Approved safety shorting probe.

portable electric equipment is issued, it should be • Before you use a tool, inspect the tool cord and
visually examined. The parts to be looked at include the plug. Don’t use a tool with a frayed cord or with
attached cable with plug (including extension cords), a damaged or broken plug. Never use spliced
making sure it is in satisfactory condition according to cables, except in an emergency.
prescribed PMS instructions. Any cable that has tears,
chafing, or exposed conductors, and any plug that has • Before using a tool, arrange the portable cables
damage should be promptly replaced. so you and others will not trip over them. The
length of extension cords used with portable tools
You should use an approved tool tester or
should not exceed 25 feet. Extension cords of
multimeter to test portable electrical equipment with its
100 feet are authorized on flight and hangar
associated extension cord connected. When using the
decks. Extension cords of 100 feet are also found
multimeter to check continuity of the ground conductor
in damage control lockers, and labeled FOR
from the tool case to the dummy receptacle, you should
EMERGENCY USE ONLY.
make sure the meter reading is less than 1 ohm. With
the multimeter still connected between the tool case and • Don’t use jury-rigged extension cords that have
ground, bend or flex the cable. The resistance must be metal handy boxes on the receptacle ends of the
1 ohm or less. If the resistance varies, you might have c o r d . All extension cords must have
broken conductors in the cord or loose connections. nonconductive plugs and receptacle housings.

Other safe practices in the use of portable • When using an extension cord with a portable
electric-power tools include the following: electric tool, always plug the tool into the

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 extension cord before you insert the extension ISOLATED RECEPTACLE CIRCUITS
cord plug into a live receptacle.
Isolated receptacle circuits are installed on all new
• After using the tool, unplug the extension cord construction ships. These circuits are individually
from the live receptacle before you unplug the isolated from the main power distribution system by
tool cord from the extension cord. Do not unplug isolation transformers. Each circuit is limited to 1,500
the cords by yanking on them. Always remove feet in length to reduce the capacitance to an acceptable
the plug by grasping the plug body. level. This design is intended to limit ground leakage
currents to 10 mA, which would produce a nonlethal
• When using portable electric tools, always wear shock. These receptacles are located where personnel
rubber gloves and eye protection. usually plug in electric-power tools or appliances. To
• If you notice a defect, return the tool to the ship’s maintain a safe level of leakage currents, make sure the
tool issue room (TIR). isolated receptacle circuits are free of all resistance grounds.

• When tools produce hazardous noise levels, wear

hearing protection. TEST EQUIPMENT

Another good practice to establish (at the discretion Test equipment is precision equipment that must be
of the commanding officer) is to list the portable handled with care if it is to perform its designed
equipment that requires testing more or less often than functions accurately. Some hazards to avoid when
once a month, depending on conditions in the ship. using test equipment include rough handling, moisture,
Where PMS is installed, tests should be conducted and dust.
following the maintenance requirement cards (MRCs). Rough handling includes bumping or dropping
equipment. Bumping or dropping test instruments may
ELECTRIC SOLDERING IRONS distort the calibration of the meter or short-circuit the
elements of an electron tube within the instrument.
When using and handling an electric soldering iron, Moisture effects are minimized in some types of
you can avoid burns or electric shock by taking the electronic test equipment, such as signal generators and
following precautions: oscilloscopes, by built-in heaters. Operate these heaters
• Grasp and hold the iron by its handle. Always for several minutes before applying the high voltage to
the equipment.
assume a soldering iron is hot, whether it is
plugged in or not. Never use an iron that has a The meter is the most delicate part of test
frayed cord, damaged plug, or no safety equipment. You should protect a meter by making sure
inspection tag. the amplitude of the input signal being tested is within
the range of the meter.
• Hold small soldering workplaces with pliers or a
suitable clamping device. Never hold the work Since the moving coils of the meter in electric test
in your hand. equipment are of the limited-current type, they can be
permanently damaged by excessive current. When
• Always place the heated iron in its stand or on a
using test equipment, you should observe the following
metal surface to prevent fires or equipment damage. safety precautions and procedures:
• Clean the iron by wiping it across a piece of
• Never place a meter near a strong magnetic field.
canvas placed on a suitable surface. Don’t hold
the cloth in your hand. Don’t swing the iron • Whenever possible, make the connections when
to remove excess hot solder. Swinging the iron the circuit is de-energized.
could cause a fire in combustible materials or
• When connecting an ammeter, current coil of a
burn other personnel in the area.
wattmeter, or other current-measuring device,
• Before soldering electrical or electronic always connect the coils in series with the
equipment, make sure it is disconnected from its load-never across the line.
power supply.
• To measure a circuit, the potential coil of a
• After soldering, disconnect the iron from its wattmeter, or other instrument, connect the
power supply. Let it cool before you store it. voltmeter across the line.

1-12
• Extend wires attached to an instrument over the • Only authorized maintenance personnel having
back of the workbench or worktable on which the proper approval should be permitted to gain
instrument is placed, and away from access to enclosures, connect test equipment, or
test energized circuits or equipment.
observers —never over the front of the
workbench. • Circuits should be de-energized and checked for
• Place a mat or folded cloth under the test continuity or resistance, rather than energized
and checked for voltage at various points.
instrument when used in high-vibration areas.
• When a circuit or a piece of equipment is
• Remember that interlocks aren’t always
energized, never service, adjust, or work on it
provided and, even when provided, they don’t alone.
always work. Removing the case or rear cover
of an instrument not equipped with an interlock
INSULATING AND PROTECTIVE
allows access to circuits carrying voltages
EQUIPMENT
dangerous to human life.
Insulated workbenches and decks and the use of
• Don’t change tubes or adjust inside equipment rubber gloves are just a few of the requirements for
with the high-voltage supply energized. personnel protection. The amount and type of personal
• Under certain conditions, dangerous potentials protective equipment used is dictated by the type of
work being performed and the area in which it is located.
may exist in circuits. With the power controls in
the off position, capacitors can still keep their WORKBENCHES
charge. To avoid electric shock, always As an EM, you test and repair equipment on a
de-energize the circuit, discharge the capacitors, workbench in the electric shop. You must make sure
and ground the circuit before working on it. your workbench is properly insulated. Figure 1-4 shows

Figure 1-4.—A typical electric workbench.

1-13
the construction features of a safe electric or electronic the workbench. The inside of drawers and cabinets need
workbench. The work surface, or top, is usually 30 not be insulated as they should be left closed while
inches wide and 4 feet long. The bench must be secured working on energized circuits or equipment. Don’t
to the deck. defeat the purpose of the insulation by attaching vises,
locks, hasps, hinges, or other hardware with metal
Where electrical vinyl sheet deck covering is not
through bolts to the metal parts of the workbench. When
used, matting is installed over the minimum area (not
mounting hardware items, insulate them from the
less than 3 feet wide) to prevent electric shock. workbench.
Additionally, a rubber matting 3 feet wide is installed to
insulate the walkway in front of insulated workbenches The workbench must have type D, size 10
where electrical grade vinyl sheet is not specified. grounding leads that are at least 54 inches in length
according to MIL-W-16878 (fig. 1-5). The ground leads
The top of the working surface of an electric or must be secured to the ship’s structure or at the back of
electronic workbench must be insulated with 3/8-inch the workbench and must be equipped at the free end with
Benelex 401. All other surfaces should be covered with a So-ampere power clip (type PC) and insulated sleeving
1/8-inch laminate, including kneeholes under auxiliary (both conforming to Federal Specification W-C-440).
worktables and bulkheads or other hull structures or One grounding lead should be installed for every 4 feet
equipment attached to the hull that are within 3 feet of of workbench length to ensure positive grounding of the

Figure 1-5.—Installation of grounding cable for electric workbench.

1-14
equipment being tested. The grounding leads installed
in ships with wooden hulls should be the same as those
installed in ships with steel hulls except that the leads
should be secured to the ship’s electrical grounding
system. A bare, solid-copper conductor, not less than
83,690 circular roils, must be used for the main internal
grounding wire.
Test bench receptacle panels should be installed on
test benches where power at various voltages and
Figure 1-6.—Danger sign to he posted near electric
frequencies (other than ship’s service) are needed for workbench.
testing equipment.
workbenches, satisfy this requirement. The disconnect
The illumination requirements vary between those switch must not be located on the workbench. The safe
for general-purpose workbenches and workbenches for
place to install the disconnect switch is away from the
the repair of instruments, such as typewriters and meters.
bench, between the entrance to the space and the bench.
A dummy outlet is installed near the workbench to
The required safety signs for a workbench must
check the grounding conductor on portable tools before
conform with General Specifications for the Overhaul
they are issued
of Surface Ships (GSO), Section 665. Signs that must
Workbench receptacle connectors should not be posted include the following:
supply other types of loads. AU receptacles on the
workbench must be connected to a common or an • The sign shown in figure 1-6 must be posted near
individual isolation transformer. The transformer must each workbench. This sign must be reproduced
be either 450/120-volt supplied from a 450-volt load locally on 0.05-inch aluminum engraved with red
center or a 120/120-volt supplied from a 120-volt enamel letters.
distribution point.
• A sign giving artificial respiration instructions
General Specifications for the Overhaul of Surface (NSN 0177-LF-226-3400) must also be posted.
Ships (1991), Section 320, requires that a means of
disconnecting power be provided in the compartment in • A sign showing an approved method to rescue
which the workbenches are installed. Distribution personnel (fig. 1-7) in contact with energized
panels, when installed in the same compartment as the circuits. This sign is locally produced.

Figure 1-7.—Instructions for rescuing personnel in contact with energized circuits.

1-15
DECK MATTING RUBBER GLOVES

There are four classes of rubber insulating gloves.

An insulating deck covering prevents electric shock
The primary feature being the wall thickness of the
to anyone who may touch bare, energized, ungrounded
gloves and their maximum safe voltage, which is
circuits. You must use approved rubber floor matting in identified by a color label on the glove sleeve. Use only
electrical and electronic spaces to eliminate accidents rubber insulating gloves marked with a color label.
and afford maximum protection from electric shock. Table 1-1 contains the maximum safe use voltage and
NSTM, chapter 634, table 634-1, gives approved deck label colors for insulating gloves approved for Navy use.
coverings for every space in your ship. Accident
Before using rubber gloves, carefully inspect them
investigations often show that the floors around
for damage or deterioration. To inspect robber gloves
electrical and electronic equipment had been covered for tears, snags, punctures, or leaks that are not obvious,
only with general-purpose black rubber matting. The hold the glove downward, grasp the glove cuff, and flip
electrical characteristics of this type of matting do not the glove upward to trap air inside the glove. Roll or
provide adequate insulation to protect against electric fold the cuff to seal the trapped air inside. Then squeeze
shock. There are various types of electrical grade mats the inflated glove and inspect it for damage. For
or sheet coverings conforming to Military Specification additional information on rubber gloves, refer to Naval
Mil-M-15562 that meet the requirements. Ships’ Technical Manual, chapter 300.

To ensure that the matting is completely safe, you

ELECTRICAL FIRES
must promptly remove from the matting surfaces all
foreign substances that could contaminate or impair its When at sea, fire aboard a Navy vessel is more fatal
dielectric properties. and damaging to both personnel and the ship itself than
damage from battle. The time to learn this is as soon as
Th dielectric properties of matting can be impaired you report aboard. The Navy requires that all hands must
or destroyed by oil, imbedded metal chips, cracks, holes, be damage control qualified within 6 months after
or other defects. If the matting is defective, cover the reporting aboard. You must learn the types of
affected area with a new piece of matting. Cementing fire-fighting equipment, their location, and their
the matting to the deck is not required, but is strongly operating procedures. It is too late after the fire has
recommended This prevents removal of the mat for started.
inspection and cleaning, which would leave the area
FIGHTING AN ELECTRICAL FIRE
unprotected. If the mat is not cemented, stencil an
outline of the proposed mat on the deck. Inside the mat Use the following general procedures for fighting
outline, stencil “ E L E C T R I C - G R A D E M A T an electrical fire:
REQUIRED WITHIN MARKED LINES.” Use
1. Promptly de-energize the circuit or equipment
3/4-inch or larger letters.
affected. Shift the operation to a standby circuit
Electrical insulating deck covering should be or equipment, if possible.
installed so there are no seams within 3 feet of an 2. Sound an alarm according to station regulations
electrical hazard. Where this is not possible, or the ship’s fire bill. When ashore, inform the
thermoplastic deck coverings, such as vinyl sheet
Table 1-1.—Rubber Gloves
manufactured by Lonseal, Inc., should be fused
chemically, heat welded, or heat fused with a special hot
air gun. With rubber deck coverings, fusing with heat
is not possible. A 3- or 4-inch wide strip of #51
Scotchrap 20-mil thick Polyvinyl Chloride (PVC) tape
(manufactured by Minnesota Mining and
Manufacturing Company) should be installed beneath
the seam. You also may use a 1-foot wide strip of
electrical grade deck covering under either rubber- or
vinyl-type coverings (instead of heat welding vinyl).

1-16
 fire department; if afloat, inform the officer of Table 1-2.—Types of Fire Extinguishers
the deck. Give the location of the fire and state
what is burning. If possible, report the extent of
the fire; that is, what its effects are upon the
surrounding area.
3. Secure all ventilation by closing compartment
air vents or windows.
4. Attack the fire with portable CO2 extinguishers
(or a CO2 hose reel system, if available) as
follows:

• Remove the locking pin from the release

valve.

• Grasp the horn handle by the insulated

(thermal) grip (the grip is insulated against
possible frostbite of the hand).

• Squeeze the release lever (or turn the wheel)

to open the valve and release the carbon
dioxide. At the same time, direct the discharge
flow of the carbon dioxide toward the base of
the fire.

• Aim and move the horn of the extinguisher

slowly from side to side.

• Don’t stop the discharge from the extinguisher

t o o s o o n . When the fire has been
extinguished, coat the critical surface areas
involved with carbon dioxide “snow” to cool
the substances (fuels) involved and prevent a
rekindling of the fire.

• Don’t lose positive control of the CO 2 bottle. REPAIR PARTY

ELECTRICIAN

EXTINGUISHERS As a repair party electrician, you maybe directed to

perform various tasks if battle damage occurs. These
tasks could range from donning an OBA to being a
Fire extinguishers of the proper type must be stretcher bearer. Your primary responsibilities,
conveniently located near all equipment that is subject however, will be those tasks in your rating.
to fire danger, especially high-voltage equipment. Be
You must be familiar with all electrical power
extremely careful when using fire-extinguishing
sources and distribution panels in your assigned repair
agents around electrical circuits. A stream of salt
party area. In the event of a free, the on-scene leader will
water or foam directed against an energized circuit can
decide whether or not to secure the power. If the word
conduct current and shock the fire fighters. The same
is passed to you to secure the power to a specific
danger is present, but to a lesser degree, when using
compartment or piece of equipment, do so quickly so
fresh water. Avoid prolonged exposure to high
the task of putting out the fire can be expedited.
concentrations of CO2 in confined spaces since there is
danger of suffocation unless an oxygen breathing When general quarters (GQ) sounds, the crew will
apparatus (OBA) is used. proceed to GQ stations and set material condition Zebra.
After Zebra is set, you must report to your repair party
Look at table 1-2, which contains a list of the types leader for muster and wait for further instructions. By
of fire extinguishers that are normally available for use. this time the repair locker should be opened, and you

1-11
should take an inventory of all the electrical equipment RESCUE
in the locker. This equipment will usually consist of
items such as an electrical repair kit, floodlights, When a victim is unconscious because of an electric
flashlights with spare batteries, a submersible pump, shock, you should start artificial resuscitation as soon as
casualty power cables and wrenches, extension cords, possible. Statistics show that 7 out of 10 victims are
revived when artificial resuscitation is started in less
rubber gloves, and rubber boots. After testing all the
than 3 minutes after the shock. Beyond 3 minutes, the
electrical equipment to ensure it is functional and safe,
chances of revival decrease rapidly. The person nearest
stow it in an easily accessible area.
the victim should start artificial resuscitation without
All members of the repair party are responsible for delay, and call or send others for help and medical aid.
rigging casualty power and tying it to the overhead. The
Before starting artificial resuscitation, free the
repair party electrician is responsible for proper victim from contact with electricity y in the quickest,
connection to the biscuits (from load to source) and safest way. (NOTE: This step must be done with
energizing the system. Follow standard safety extreme care; otherwise, there may be two victims
precautions, wear rubber gloves and rubber boots, and instead of one.)
stand on a section of rubber matting while making these
• If the contact is with a portable electric tool, light,
connections.
appliance, equipment, or portable extension
Tag the casualty power cable at various locations. cord, turn off the bulkhead supply switch or
Remember, you need to warn all hands of the potential remove the plug from its bulkhead receptacle.
danger that exists. A typical warning sign is shown in • If the switch or bulkhead receptacle cannot be
figure 1-8. quickly located, the suspected electric device
may be pulled free of the victim by grasping the
insulated flexible cable to the device and
RESCUE AND FIRST carefully withdrawing it clear of its contact with
AID the victim. Other persons arriving on the scene
must be clearly warned not to touch the suspected
The EM’s job is risky even under the best working equipment until it is unplugged. Aid should be
conditions. Although accidents are preventable, you run enlisted to unplug the device as soon as possible.
a good chance of getting shocked, burned, and being • If the victim is in contact with stationary
exposed to one or more of the hazards described earlier.
equipment (fig. 1-9), such as a bus bar or
If you are at the scene of an accident, you will be
electrical connections, pull the victim free if the
expected to help the victim as quickly as possible. equipment cannot be quickly de-energized or the
ship’s operations or survival prevent immediate
securing of the circuits. To save time in pulling
the victim free, improvise a protective insulation
for the rescuer. For example, instead of hunting
for a pair of rubber gloves to use in grasping the
victim, you can safely pull the victim free (if
conditions are dry) by grasping the victim’s slack
clothing, leather shoes, or by using your belt.
Instead of trying to locate a rubber mat to stand
on, use nonconducting materials, such as deck
linoleum, a pillow, a blanket, a mattress, dry
wood, or a coil of rope.
NOTE: During the rescue, never let any part of
your body directly touch the hull, metal structure,
Figure 1-8.—DANGER HIGH VOLTAGE sign. furniture, or victim’s skin.

1-18
 assume that breathing has stopped merely because a
person is unconscious or because a person has been
rescued from an electrical shock. Remember, DO NOT
GIVE ARTIFICIAL VENTILATION TO A PERSON
WHO IS BREATHING NATURALLY. There are two
methods of giving artificial ventilation: mouth-to-
mouth and mouth-to-nose.
For additional information on performing artificial
ventilation, refer to Standard First Aid Training Course,
NAVEDTRA 12081.

Cardiopulmonary Resuscitation

A rescuer who knows how to give cardiopulmonary

resuscitation (CPR) increases the chances of a victim’s
survival. CPR consists of artificial ventilations and
external heart compressions. The lungs are ventilated
by the mouth-to-mouth or mouth-to-nose techniques;
Figure 1-9.—Pushing a victim away from a power line.
the compressions are performed by pressing the chest
with the heel of your hands. ‘he victim should be lying
face upon a firm surface. The procedure forgiving CPR
RESUSCITATION
is given in figure 1-10.

Methods of resuscitating or reviving an electric

shock victim include artificial respiration/ventilation (to WARNING
reestablish breathing) and external heart massage (to
reestablish heart beat and blood circulation). CPR should not be attempted by a
rescuer who has not been properly trained.
Artificial Ventilation
One-Rescuer Technique
A person who stopped breathing is not necessarily
dead but is in immediate critical danger. Life depends
The rescuer must not assume that an arrest has
on oxygen that is breathed into the lungs and then carried
occurred solely because the victim is lying on the deck
by the blood to every cell. Since body cells cannot store
and looks unconscious. First, try to arouse the victim
oxygen, and since the blood can hold only a limited
by gently shaking the shoulders and try to get a response;
amount (and only for a short time), death will result from
loudly ask, “Are you OK?” If there is no response, place
continued lack of breathing.
the victim face upon a firm surface. Kneel at a right
The heart may continue to beat and the blood may angle to the victim, and open the airway, using the head
still be circulated to the body cells for some time after tilt-neck lift or the jaw thrust methods previously
breathing has stopped. Since the blood will, for a short discussed. Look for chest movements. Listen and feel
time, contain a small supply of oxygen, the body cells for air coming from the nose or mouth for at least 5
will not die immediately. Thus, for a very few minutes, seconds. If the pulse is absent, call for help and begin
there is some chance that the person’s life maybe saved. CPR.
A person who has stopped breathing but who is still alive
Locate the lower margin of the victim’s rib cage on
is said to be in a state of respiratory failure. The first-aid
the side closest to you by using your middle and index
treatment for respiratory failure is called artificial
fingers. Then move your fingers up along the edge of
ventilation.
the rib cage to the notch (xiphoid process) where the ribs
The purpose of artificial ventilation is to provide a meet the sternum in the center of the lower chest. Place
method of air exchange until natural breathing is the middle finger on the notch, and place the index finger
reestablished. Artificial ventilation should be given next to it. Place the heel of the other hand along the
only when natural breathing has stopped; it must NOT midline of the sternum, next to the index finger. You
be given to any person who is still breathing. Do not must keep the heel of your hand off the xiphoid process

1-19
 Figure 1-10.—Instructions for administering CPR.

(fig. 1-11). A fracture in this area could lacerate the fingers or extend them straight out, and KEEP THEM
liver. OFF THE VICTIM’S CHEST! See figure 1-12.

Place the heel of one hand directly on the lower half With the elbows locked, apply vertical pressure
of the sternum, two fingers up from the notch, and the straight down to depress the sternum (adult) from 1 1/2
heel of the other on top of the first hand. Interlock your to 2 inches. Then release the pressure, keeping the heels

1-20
 Figure 1-11.—Xiphoid process.

of the hands in place on the chest. This process After 15 compressions, you must give the victim 2
compresses the heart between the sternum and the ventilations. Continue for four full cycles of 15
victim’s back, thus pumping blood to the vital parts of compressions and 2 ventilations. Then take 5 seconds
the body. to check for the carotid pulse and spontaneous
If you use the proper technique, a more effective breathing. If there are still no signs of recovery,
compression will result, and you will feel less fatigue. continue CPR. If a periodic check reveals a return of
Ineffective compression occurs when the elbows are not puke and respiration, stop CPR. Closely watch the
locked, the rescuer is not directly over the sternum, or
victim’s puke and respirations, and be prepared to start
the hands are improperly placed on the sternum.
CPR again if required If a pulse is present but no
When one rescuer performs CPR, the ratio of respiration, continue to give the victim one ventilation
compressions to ventilations is 15 to 2. It is performed every 5 seconds and check the pulse frequently.
at a rate of 80 to 100 compressions per minute. Vocalize
Let’s review the steps for one-rescuer CPR:
“one, and two, and three,” and so on, until you reach 15.
1. Determine whether the victim is conscious.
2. Open the airway (it may be necessary to remove
the airway obstruction).
3. Link, listen, and feel.
4. Ventilate two times.
5. Check the pulse—if none, call for help.
6. Begin the compression-ventilation ratio of 15 to
2 for four complete cycles.

7. Check again for a pulse and breathing. If no

change, continue the compression-ventilation
ratio of 15 to 2 until the victim is responsive,
until you are properly relieved, until you can no
longer continue because of exhaustion or until
the victim is pronounced dead by a medical
officer. For additional information refer to
Figure 1-12.—Interlocking fingers to help keep fingers ON the Standard First Aid Training Course,
chest Wall. NAVEDTRA 12081.

1-21
WOUNDS There are many classifications of wounds, but we
will discuss only the three common types.
A wound or breaking of the skin, is another problem Abrasions. Abrasions are made when the skin is
that could arise, and in some instances, could be the rubbed or scraped off. Rope burns, floor burns, and
result of an electric shock. An EM could accidentally skinned knees or elbows are common examples of
come in contact with an energized circuit, causing a loss abrasions. There is usually minimal bleeding or oozing
of balance. This could result in a minor or serious injury. of clear fluid.
Because you could be in a critical situation to save
someone’s life, or even your own, you should know the Incisions. Incisions, commonly called cuts, are
basics of first aid and the control of bleeding. wounds made with sharp instruments such as knives,

Figure 1-13.—Pressure points for control of bleeding.

1-22
razors, or broken glass. Incisions tend to bleed very and mark a large T on the victim’s forehead to alert
freely because the blood vessels are cut straight across. medical personnel that the patient has a tourniquet.

Lacerations. Lacerations are wounds that are tom,

rather than cut. They have ragged, irregular edges and WARNING
masses of tom tissue underneath. Lacerations are
usually made by blunt forces, rather than sharp objects. Remember, use a tourniquet as a last
resort to control bleeding that cannot be
They are often complicated by crushing of the tissues as
controlled by other means. Tourniquets
well.
should be removed by medical personnel
For additional information on first aid, refer to the only.
Standard First Aid Training Course, NAVEDTRA
12081. BURNS
The principal dangers from burns are shock and
BLEEDING
infection. Direct all casualty care measures toward
You should use the direct-pressure method to combating shock, relieving pain, and preventing
control bleeding. Use a compress made with a clean rag, infection.
handkerchief, or towel to apply direct pressure to the
Classification of Burns
wound. If the direct-pressure method does not stop the
bleeding, use the pressure point (fig. 1-1 3) nearest the Burns may be classified according to their cause as
wound. thermal, chemical, or electrical.

Use a tourniquet on an injured limb only as a last Thermal burns. A thermal burn is the direct result
of heat caused by fire, scalding, sun, or an explosion.
resort; for example, if the control of hemorrhaging
cannot be stopped by other means. Apply a tourniquet Chemical burns. A chemical burn is caused by
above the wound (towards the trunk) and as close to the chemical action, such as battery acid on the skin.
wound as practical. Electrical burns. An electrical burn is caused by
Any long, flat material can be used as a band for a electrical current passing through tissue or the
tourniquet—belts, stockings, flat strips of rubber, or a superficial wound caused by electrical flash.
neckerchief. Only tighten the tourniquet enough to stop Bums are also classified as first, second, or third
the flow of blood. Use a marker pencil, crayon, or blood degree, based on the depth of skin damage (fig. 1-14).

Figure 1-14.—First-, second-, and third-degree burns.

1-23
 First-degree burns. A first-degree burn is the water. Apply a simple sterile dressing of fine-mesh, dry
mildest. Symptoms are reddening of the skin and mild gauze over the area to protect it from infection. Casualty
pain. treatment for first-degree burns needs little attention
beyond self-care.
Second-degree burns. A second-degree burn is
more serious. Symptoms include blistering of the skin, When emergency treatment of the more serious
severe pain, some dehydration, and possible shock. second-degree burns and third-degree burns is required,
treat the patient for shock first. Make the patient as
Third-degree burns. A third-degree burn is
comfortable as possible, and protect the person from
characterized by complete destruction of the skin with
cold, excessive heat, and rough handling.
charring and cooking of the deeper tissues. This is the
most serious type of burn. It produces a deep state of The loss of body fluids is the main factor in burn
shock and causes more permanent damage. It is usually shock. If the patient is conscious, able to swallow, and
not as painful as a second-degree burn because the has no internal injuries, you can give the patient frequent
sensory nerve endings are destroyed. small amounts of coffee, tea, fruit juice, or sugar water.
To enable trained personnel to determine the kind
Burn Emergency Treatment of treatment required, no not apply medication to burns
during emergency treatment. Pain is closely associated
The degree of the burn, as well as the skin area with the degree of shock and should be relieved as soon
involved, determines the procedures used in the as possible. When available, ice water is an effective
treatment of burns. Large skin areas require a different pain reducer. Flooding with lots of clean, cool fresh
approach than small areas. To estimate the amount of water also helps if not too much force is used. In electric
skin area affected, use the rule of nines (fig. 1-15). shock cases, burns may have to be ignored temporarily
As a guideline, burns exceeding 20 percent of the while the patient is being revived.
body surface endanger life. Burns covering more than After treating the patient for pain and shock, apply
30 percent of the body surface are usually fatal. a compress and bandage to protect the burned area. If
If time and facilities permit caring for patients with a universal protective dressing is not available, use a
supeficial burns, clean the burned area with soap and fine-mesh gauze. Remove constricting articles of
clothing and ornaments, and immobilize and elevate the
burned area.
Evacuate patients with extensive deep burns to a
medical facility for treatment as rapidly as possible.
Pain should be alleviated and shock must be controlled
before and during evacuation.
Clothing that sticks to a burn maybe cut around the
burn and the adhering cloth allowed to remain until
removed by medical personnel. The area of the burn is
usually sterile; therefore, be careful not to contaminate
it.

HEARING CONSERVATION AND

NOISE ABATEMENT
Historically, hearing loss has been recognized as an
occupational hazard related to certain trades such as
blacksmithing and boilermaking. Modem technology
has extended the risk to many other activities, such as
those where presses, forging hammers, grinders, saws,
internal combustion engines, or similar high-speed,
high-energy processes are used. Exposure to
high-intensity noise occurs as a result of either impulse
Figure 1-15.—Rule of nines. or blast noise (gunfire or rocket fire) and from

1-24
continuous or intermittent sounds, jet or propeller compared to the reference (base line) to determine if a
aircraft, marine engines, and machinery. hearing threshold shift has occurred.
Hearing loss has been and continues to be a source
HEARING PROTECTIVE DEVICES
of concern within the Navy. Hearing loss attributed to
occupational exposure to hazardous noise, the high cost
All personnel must wear hearing protective devices
of related compensation claims, and the resulting drop
when they must enter or work in an area with noise
in productivity and efficiency have highlighted a
levels greater than 84 dB. There are many types of
significant problem that requires considerable attention.
hearing protection—inserts of numerous styles
The goal of the Navy Hearing Conservation and Noise
(earplugs) and circumaurals (earmuffs).
Abatement Program is to prevent occupational
noise-related hearing loss among Navy personnel. The Single hearing protection. Single hearing
program includes the following elements: protection is required when in areas where the noise
level is above 84 dB.
• Work environments are surveyed to identify
potentially hazardous noise levels and personnel Double hearing protection. Double hearing
at risk. protection is required when the noise level is 104 dB or
higher.
• If environments contain or equipment produces
potentially hazardous noises, they should be IDENTIFYING AND LABELING
modified to reduce the noise to acceptable levels.
OF NOISE AREAS
Where engineering controls are not feasible,
administrative controls and/or the use of hearing
Industrial hygienists use a noise level meter to
protection devices are employed.
identify noise hazardous areas. All noise hazardous
• Periodic hearing testing is conducted to monitor areas are labeled using a HAZARDOUS NOISE
the program. WARNING decal (fig. 1-16). Post this decal at all
accesses.
• Educating Navy personnel in hearing
conservation programs is vital to the overall You will find further information on hearing
success. conservation in OPNAVINST 5100.23.

HEARING TESTING HEAT STRESS PROGRAM

All personnel required to work in designated noise Heat stress is any combination of air temperature,
hazard areas or with equipment that produces sound thermal radiation, humidity, airflow, and workload that
levels greater than 84 decibels (dB) or 140 dB
sound/pressure levels are entered in the hearing testing
program. The hearing testing program includes a
reference hearing test and monitored hearing tests.

Reference (Base Line) Hearing Test

All military personnel should receive a reference

hearing test upon entry into naval service. his test is
called the base line.

Monitored Hearing Tests

If a person works in a noise hazard area, a hearing

test is conducted within 90 days of reporting and
repeated at least annually. Hearing tests are conducted
when there are individual complaints or difficulties in
understanding conversational speech or a sensation of
ringing in the ears. The 90-day or annual audiogram is Figure 1-16.—Hazardous noise warning decal.

1-25
may stress the human body as it attempts to regulate its Afloat, OPNAVINST 5100.19, provide requirements for
temperature. Heat stress becomes excessive when your handling, storage, and disposal of hazardous materials.
body’s capability to adjust to heat is exceeded. This
condition produces fatigue, severe headaches, nausea, AEROSOL DISPENSERS
and poor physical and/or mental performance.
Prolonged exposure to heat stress could cause you to If personnel deviate from or ignore procedures
have heatstroke or heat exhaustion. prescribed for selecting, applying, storing, or disposing
Primary factors that increase heat stress conditions of aerosol dispensers, they have been poisoned, burned,
include the following: or have suffered other physical injury. Material Safety
Data Sheets (MSDSs) contain specific precautions and
• Excessive steam and water leaks safe practices for handling aerosol dispensers. You can
• Boiler air casing leaks get MSDSs from your supervisor. However, you can
guard against poisoning, fire, explosion, pressure, and
• Missing or deteriorated lagging on steam piping other hazards associated with aerosols by regarding all
and machinery aerosols as flammable. You can prevent an injury or
hazard by the following basic rules:
• Ventilation systems ductwork clogged or an
inoperative fan motor Poisoning. All areas where people use aerosols
require adequate ventilation. Ventilation is critical if the
• Ships operating in hot or humid climates
aerosol is toxic or flammable. Exhaust ventilation is
Dry-bulb thermometers are used to determine the needed to remove harmful vapors, or additional supply
heat stress conditions in areas of concern. Permanently ventilation to dilute vapors to a safe level. When
mounted dry-bulb thermometers are installed at watch ventilation is inadequate or absent, you must wear
stations. Readings should be taken and recorded at least respiratory protection.
once a watch period. When the reading exceeds 100°F,
Chemical Burns. Avoid spraying your hands, arms,
a heat survey must be ordered to determine the safe stay
face, or other exposed parts of the body. Some liquid
time for personnel.
sprays are strong enough to burn the skin, while milder
The heat survey is taken with a wet-bulb globe sprays may cause rashes.
temperature (WBGT) meter. Then, these readings are
Fire. Keep aerosol dispensers away from direct
compared to the physiological heat exposure limits
sunlight, heaters, and other sources of heat. Do not store
(PHEL) chart. After comparing the readings with the
dispensers in an area where the temperature can exceed
PHEL chart, the safe stay time for personnel can be
the limit printed on the container. Do not spray volatile
determined.
substances on warm or energized equipment.
Refer to OPNAVINST 5100.19 for further
Explosion. Do not puncture an aerosol dispenser.
information on the heat stress program and procedures.
Discard used dispensers in approved waste receptacles
that will not be emptied into an incinerator.
HAZARDOUS MATERIALS
PAINTS AND VARNISHES
Hazardous materials include anything that may
pose a substantial hazard to human health or to the
You must take special precautions when removing
environment because of their quantity, concentration, or
paint from or repainting electrical equipment. In
physical or chemical characteristics when purposefully
general, avoid removing paint from electrical
or accidentally spilled. Hazardous materials include
equipment. If scraping or chipping tools are used on
flammable and combustible materials, toxic materials,
electrical equipment, insulation and delicate parts can
corrosives, oxidizers, aerosols, and compressed gases.
be damaged. Furthermore, paint dust is composed of
his section covers aerosols, paints and varnishes,
abrasive and semiconducting materials that impair the
cleaning solvents, steel wool and emery paper,
insulation. When paint must be scraped, cover all
cathode-ray tubes, and radioactive electron tubes.
electrical equipment, such as generators, switchboards,
Hazardous Material Control and Management, motors, and controllers to prevent entrance of the paint
OPNAVINST 4110.2, and Navy Occupational Safety dust. After removing paint from electrical equipment,
and Health (NAVOSH) Program Manual for Forces thoroughly clean it, preferably with a vacuum cleaner.

1-26
 Repaint electrical equipment only when necessary Avoid coming in contact with cleaning solvents.
to prevent corrosion due to lack of paint. Paint only the Always wear gloves and goggles, but especially when
affected areas. General repainting of electrical equipment is being sprayed. When spraying, hold the
equipment or enclosures for electrical equipment only nozzle close to the equipment. Do not spray cleaning
to improve their appearance is not desirable. Never solvents on electrical windings or insulation.
apply paint to any insulating surfaces in electrical
NOTE: Never use carbon tetrachloride as a
equipment. DO NOT PAINT OVER IDENTIFICA-
cleaning agent. It is a highly toxic (poisonous)
TION PLATES.
compound that is a suspected carcinogen. Its threshold
Apply electrical insulating varnish to equipment is 20 times lower than that of methyl chloroform,
only as necessary. Frequent applications of insulating making it more dangerous. (Threshold is the point
varnish build up a heavy coating that may interfere with above which the concentration of vapor in the air
heat dissipation and develop surface cracks. Do not becomes dangerous.)
apply insulating varnish to dirty or moist insulation; the NOTE: Never use volatile substances, such as
varnish will seal in the dirt and moisture and make future
gasoline, benzene, alcohol, or ether as cleaning agents.
cleaning impossible. Besides being fire hazards, they readily give off vapors
The two types of insulating varnishes commonly that injure the human respiratory system if inhaled
used in the Navy are clear baking varnish (grade CB) directly for along time.
and clear air-drying varnish (grade CA). Grade CB is
the preferred grade. If it is not possible to bake the part STEEL WOOL AND EMERY CLOTH/PAPER
to be insulated, use grade CA.
Steel wool and emery cloth/paper is harmful to the
NOTE: Shellac and lacquer are forms of varnish, normal operation of electric and electronic equipment.
but don’t use them for insulating purposes. The Naval Ships’ Technical Manual and other technical
publications warn you against using steel wool and
CLEANING SOLVENTS emery cloth/paper on or near equipment. When these
items are used, they shed metal particles. These particles
Cleaning electrical and electronic equipment with are scattered by ventilation currents and attracted by the
water-based and nonvolatile solvents is an approved magnetic devices in electrical equipment. This could
practice. These solvents do not vaporize readily. Some cause short circuits, grounds, and excessive equipment
wear.
cleaning solvents are discussed in this section.
Clean the contacts with silver polish, sandpaper, or
When it is not possible to clean with a water-based
burnishing tools. After cleaning, use a vacuum to
solvent, u s e i n h i b i t e d m e t h y l c h l o r o f o r m
remove the excessive dust.
(1,1,1—trichloroethane). Methyl chloroform is a safe
effective cleaner when used in an adequately ventilated NOTE: Never use emery cloth/paper and steel
area, and not inhaled Do not use it on warm or hot wool for cleaning contacts.
equipment.
CATHODE-RAY TUBES

WARNING Handle cathode-ray tubes (CRTs) with extreme

caution. The glass encloses a high vacuum. Because
Wear an organic vapor cartridge of its large surface area, it is subject to considerable
respirator when using 1,1,1—trichloromethane force caused by atmospheric pressure. (The total force
or make sure the work area has good local on the surface of a lo-inch CRT is 3,750 pounds, or
exhaust ventilation. nearly 2 tons; more than 1,000 pounds is exerted on its
face alone.)
When using cleaning solvents in a compartment, The chemical phosphor coating of the CRT face is
always make sure the ventilation is working properly. extremely toxic. When disposing of broken tubes, be
Rig an exhaust trunk for local exhaust ventilation if you careful not to come into contact with this compound.
expect a high vapor concentration. Keep a ready-to-use Certain hazardous materials are released if the glass
fire extinguisher close by. Never work alone in a envelope of a CRT is broken. These hazardous
compartment. materials are:

1-27
 • Thorium oxide— The radioactive decay of
thorium (thorium daughter products) and
thorium oxide are considered carcinogenic
agents.
• Barium acetate— A small residual remains after
manufacture, TLV 0.5 mg/m3.
• Barium getters— Composition unknown, 10-12
Figure 1-17.—Cathode-ray tube base structure.
grams.
Several manufacturers will dispose of returned RADIOACTIVE ELECTRON TUBES

tubes. Instructions for the return of tubes are available Electron tubes containing radioactive material are
from the manufacturer. If unable to return the CRT to now commonly used. Some tubes containing
the manufacturer for disposal, make it harmless by radioactive material contain dangerous intensity levels.
breaking the vacuum glass seal. The safest method of These tubes are marked according to military
specifications. Most tubes contain radioactive cobalt
making a CRT harmless is to place the tube in an empty
(Co-60), radium (Ra-226), or carbon (C-14); several
carton, with its face down. Then, carefully break off the contain nickel (Ni-63). Some tubes contain cesium
locating pin from its base (fig. 1-17). Complete disposal barium (CsBa-137).
instructions may be found in Navy Electricity and No hazard exists when an electron tube containing
Electronics Training Series (NEETS), NAVEDTRA radioactive material remains intact. However, a
172-06-00-82, Module 6. potential hazard exists when the electron tube is broken

Figure 1-18.—CAUTION tag (colored YELLOW).

1-28
and the radioactive material escapes. The concentration equipment or systems are not operated unless
of radioactivity in a normal collection of electron tubes permission from the responsible supervisor has been
at a maintenance shop does not approach a dangerous obtained. A CAUTION tag cannot be used if personnel
level, and the dangers of injury from exposure are slight. or equipment could be endangered while performing
However, at major supply points, the storage of large evolutions using normal operating procedures; a
quantities of radioactive electron tubes in a small area DANGER tag is used in this case.
may create a hazard. For this reason, personnel working
DANGER TAG
with equipment that contains radioactive electron tubes
or in areas where many radioactive tubes are stored Safety must always be practiced by persons
should read and become thoroughly familiar with the working around electric circuits and equipment.
safety precautions and safe-handling practices outlined Practicing safety prevents injury from electric shock and
in Section 1, Radiac EIMB HandBook, NAVSEA from short circuits caused by accidentally placing or
SE000-00-EIM-050. dropping a conductor of electricity across an energized
line. The arc and fire started by these short circuits, may
cause extensive damage to equipment and serious injury
TAG OUT to personnel.

Equipment needing repair must be de-energized and No work will be done on electrical circuits or
tagged out by use of either a CAUTION or DANGER equipment without permission from the proper authority
tag. and until all safety precautions are taken. One of the
most important precautions is the proper use of
CAUTION TAG
DANGER tags, commonly called RED tags (fig. 1-19).
A CAUTION tag (fig. 1-18) is a YELLOW tag. It
is used as a precautionary measure to provide temporary Danger tags are used to prevent the operation of
special instructions or to show that unusual caution must equipment that could jeopardize your safety or endanger
be exercised to operate equipment. These instructions the equipment systems or components. When
must state the specific reason that the tag is installed. equipment is red tagged, under no circumstances will
Use of phrases such as DO NOT OPERATE WITHOUT it be operated. When a major system is being repaired
EOOW PERMISSION is not appropriate since or when PMS is being performed by two or more repair

Figure 1-19.—DANGER tag (colored RED).

1-29
groups, such as ENs and EMs, both parties will hang • Providing information on safety precautions and
their own tags. This prevents one group from operating other matters
or testing circuits that could jeopardize the safety of
Administrative, supervisory, and training tasks have
personnel from the other group.
a direct relationship to the job—overhauling the electric
No work is done on energized or de-energized motor.
switchboards before approval of the commanding
The only way to keep things running smoothly is to
officer, engineer officer, and electrical officer. Because
take your administrative supervisory and training
of the continuous use of the tag-out system by EMs in
responsibilities seriously. Repair jobs cannot get started
their day-to-day activities, they are expected to be the
unless a variety of administrative, supervisory, and
experts in the interpretation of the Equipment Tag-Out
training functions are performed on a continuing basis.
Bill, OPNAVINST 3120.32B, chapter 6, paragraph
630.17. • Materials, repair parts, and tools must be
All supply switches or cutout switches from which available when they are needed.
power could be fed should be secured in the off or open • Jobs must be scheduled with regard to the
(safety) position, and red tagged. Circuit breakers are urgency of other work.
required to have a handle locking device installed as
shown in figure 1-20. The proper use of red tags cannot • Records must be kept and required reports
be overstressed. When possible, double red tags should submitted.
be used, such as tagging open the main power supply
• Personnel must be in a continuous state of
breaker and removing and tagging the removal of fuses
training to assume increasingly important duties
of the same power supply.
and responsibilities.
ADMINISTRATION
ADMINISTRATION, SUPERVISION,
AND TRAINING The engineering department administrative
organization is setup to provide for proper assignment
The higher you go in the Navy, the more
of duties and for proper supervision of personnel.
administrative, supervisory, and training tasks you will
However, no organization can run itself. Senior EMs
be required to perform. This section addresses some of
should ensure that all pertinent instructions are carried
your responsibilities as a senior petty officer for
out and that all machinery, equipment, and electrical
supervising and training others.
systems are operated following good engineering
When a shop is assigned a motor overhaul job, the practices. Other responsibilities include the posting of
senior petty officers duties involve administration, instructions and safety precautions next to operational
supervision, and training all at the same time. equipment and ensuring that they are followed by all
personnel. Watch standers must be properly supervised
As an administrator, your job includes the
to ensure that the entire engineering plant is operated
following:
with maximum reliability, efficiency, and safety.
• Scheduling the job
To monitor your plant’s status and performance, you
• Checking on the history of the motor need to know which engineering records and reports are
required. Reports regarding administration,
• Making sure that the required forms and reports maintenance, and repair of naval ships are prescribed by
are submitted directives from such authorities as the Type
As a supervisor, your job involves the following: Commander, Naval Ship Systems Command
(NAVSEA), and Chief of Naval Operations (CNO).
• Overseeing the actual work These records must be accurate and up to date.
• Making sure it is done correctly As an EM1 or EMC, your supervisory duties will
require a greater knowledge of engineering records and
As a trainer, your job involves the following:
administrative procedures than you needed at the EM2
• Providing information and instruction on repair or EM3 level. Your supervisory duties and
parts responsibilities require a knowledge of the following:

• Providing information on rewind procedures • Engineering records

1-30
 Figure 1-20.—Handle-locking devices for circuit breakers.

• Infections afloat and can be obtained as indicated in the Navy Stock

List of Publications and Forms, NAVSUP 2002. Since
• Administrative procedures these forms are revised periodical y, personnel must be
• Training procedures sure that the most current are obtained. When
complementary forms are necessary for local use, make
• Preventive maintenance sure that an existing standard form will serve the
• Repair procedures purpose.
STANDARD SHIP ORGANIZATION
Information on the most common engineering
records and reports is given in this section. These The responsibility for organization of a ship’s crew
standard forms are prepared by the various systems is assigned to the commanding officer by U.S. Navy
commands and CNO. The forms are for issue to forces regulations. The executive officer is responsible, under

1-31
 Figure 1-21.—Typical engineering departments.

the commanding officer, for the organization of the department are subordinate to the chief engineer, and all
command. The department heads are responsible for orders issued by him or her must be obeyed A structural
the organization of their departments for readiness in organization chart for the department is shown in figure
battle and for assigning individuals to stations and duties 1-21.
within their respective departments. The Standard
The chief engineer must conform to the policies and
Organization and Regulations of the U.S. Navy,
OPNAVINST 3120.32B, prescribes this administrative comply with the orders of the commanding officer.
organization for all types of ships. For more Besides general duties that are applicable to all
information on standard ship organization, refer to department heads on naval ships, the engineering officer
Engineering Administration, NAVEDTRA 12147. has certain duties peculiar to his or her position.

THE ENGINEER OFFICER The engineer may confer directly with the
The engineering officer (chief engineer) is the head commanding officer in matters relating to the
of the engineering department on naval ships. As a engineering department when he or she believes such
department head, the chief engineer represents the action is necessary. The engineering officer will report
commanding officer in all matters pertaining to the to the executive officer for the administration of the
department. All personnel in the engineering engineering department.

1-32
ASSISTANTS TO THE ENGINEER OFFICER specific duties as may be required for the proper
performance of the engineering department. The
The engineering officer is assigned assistants for engineering officer is responsible for ensuring that his
damage control, main propulsion, electrical, and other or her assistants perform their assigned duties.

1-33
ACCOUNTABILITY subordinate’s problems within their own command’s
resources, and it their duty to do so.
The outlook of the young sailor today indicates that
In meeting this responsibility, counseling is a
the degree of leadership success depends less on the
valuable tool. Whether conducted formally in the work
position of the leader than upon the leader’s ability to
center office or informally on the flight deck, counseling
gain the full commitment of those under him or her. This
is intended to reward a person for a job well done or to
has come about because todays’ sailor is more
point out some deficiency to the sailor before it becomes
intelligent, better educated. They are asking more
probing questions—they will not follow blindly. Their a problem. When counseling a person for a deficiency,
personal commitments will not be given just because of the outcome goal should be pointed out to the
a leader’s position; it has to be generated by the leader person—that is for the person to act to correct the
as a competent individual. In developing this deficiency before it becomes a problem. If the person
competency, accountability for one’s actions and for being counseled should require help to attain the goal,
those under him or her cannot be ignored. it must be made available.

The relationship between responsibility, authority, The act of counseling is something that takes
and accountability has never been better expressed than practice and experience. Broken down into its basics,
by Admiral George Anderson, when he was Chief of counseling for deficiencies consists of six steps:
Naval Operations. He stated, “We cannot evade any of
1. Reinforce relationships. Set the relationship
our own responsibilities; while it is perfectly
between the person being counseled and the
appropriate to single out a junior as having been
counselor at the beginning of the session. The
responsible for a success, the responsibility for failure
person counseled (junior) should be aware that
must always be retained by the senior officer.”
the deficiency is not approved by the command
or the counselor (senior).
COUNSELING
2. Identify the problem. The person being
It is the responsibility of every senior petty officer counseled may not have been aware that the
in the navy to help those under him or her solve their action/inaction was a problem. In identifying
problems. Senior petty officers have the ability and the problem the person must be made aware why
know-how to solve the vast majority of their the deficiency is a problem.

1-34
 3. Acknowledgement. In order to expect positive commanding officers responsible for normal and
change, the person being counseled must agree on-the-job rating training. It was also designed to
that the deficiency pointed out is in fact a develop and register with the National Office of the
deficiency and requires change. Bureau of Apprenticeship and Training, U.S.
4. Goal identification. Once the deficiency is Department of Labor, programs of apprenticeship for
identified, it is the counselor’s job to help the active-duty naval personnel in occupations closely
subordinate identify the means by which the related and applicable to the needs and requirements of
deficiency will be corrected In setting the goal private industry. In many instances, current Navy
for correction, the time allowed for the training and on-the-job experience will, if properly
correction to take place must be defined. documented, satisfy the requirements of private
5. Termination of the counseling session. In industry for the training of apprentices in nationally
terminating the session, the counselor reinforces recognized occupations.
that the subordinate is a worthwhile member of The objectives of the National Apprenticeship
the team and his or her welfare is a valid concern Standards of the United States Navy are the following:
of the command and the counselor.
1. Provide registered certification of the rate
6. Follow up. At the preset time setup in the goal
training of Navy personnel
identification, the counselor must see that the
deficiency has been corrected. Periodic 2. Achieve recognition of the Navy person equal
monitoring after that should prevent further to his or her civilian counterpart.
problems.
Registration with the Bureau of Apprenticeship and
Used correctly, counseling will prevent most Training (BAT), U.S. Department of Labor, for naval
problems from becoming serious or out-of-hand. occupational specialties is mutually beneficial to the
Counseling records, both good and bad, are valuable Navy, to the individual, and to private industry. You
sources of information when writing performance should ensure that your personnel are familiar with this
evaluations.
program. Processing of applications for registration is
administered by the Branch Head, EM A School SSC,
TRAINING PROGRAMS
NTC, Great Lakes.

As an EM1 or EMC, you are required to establish

and/or maintain a training program for your work center Personnel Qualification Standards (PQS)
personnel. On smaller ships you might be the division
officer, responsible for a number of work centers. In The PQS Program (OPNANINST 3500.34B) is a
these programs you are required to teach the proper method of qualifying officer and enlisted personnel to
methods of equipment operation, repair, and safety. You perform assigned duties. PQS is a written compilation
should use all the materials available to you, including of knowledge and skills required to qualify for a specific
teaching aids such as manufacturer’s technical manuals, watch station, maintain a specific equipment or system,
instructions, or training manuals. In addition you or perform as a team member within the assigned unit.
should know what schools are available to your workers PQS is in the format of a qualification guide, which asks
and try to get quotas for eligible and deserving personnel the questions a trainee must answer to verify readiness
(for example, EM A or C).
to perform a given task. It also provides a record of the
progress and final certification. The PQS approach to
Apprenticeship Training
training is based on individual learning. The learner has
the complete written program in hand. The operational
The Apprenticeship Program for Electrical
supervisor serves as both a source for specific assistance
Repairers (DOT Code 829.28 1-014) was started in
1976. It was established under the authority of the and as quality control over the learning process through
Secretary of the Navy and Secretary of Labor as the certification of completion of each step. NAVEDTRA
National Apprentice Standards for the United States 43100-1, Handbook on Personnel Qualification
Navy. The purpose of establishing the National Standards, provides information on the PQS concept
Apprenticeship Standards for the United States Navy and describes its implementation into the training
was to provide general policy and guidance to program of operational units of the Navy.

1-35
 SUMMARY the various administrative duties to which you may be
This chapter contains general information that assigned. For additional information, refer to Naval
should familiarize you with the EM rating, means of Ship’s Technical Manual, chapters 079, volume 2,090,
reducing accidents and preventing many hazardous and 300, OPNAVINSTs 4110.2, 5100.19, and 5100.23,
conditions in engineering spaces and workshops, and and NAVEDTRA 12081.

1-36
 CHAPTER 2

ELECTRICAL INSTALLATIONS

The proper installation and maintenance of the As an EM, you will work on electric cables.
various electrical systems aboard ship are the To do this, you must be able to recognize the
Electrician’s Mate (EM) job. The repair of battle purpose and identify various types, sizes, capacities,
damage, alterations, and some electrical repairs may and uses of shipboard electrical cables. Also,
require changes or additions to the ship’s cables and you must be able to select, install, and maintain
control and protective devices. You may be required to cables so they will be functional. To maintain an
inspect, test, and approve new installations during electrical system in proper operating condition,
shipyard overhaul or tender availabilities. you must know the purpose, construction, installation,
and required testing procedures for electrical
cables.

LEARNING OBJECTIVES An important reference for you is the Cable

Comparison Handbook, MIL-HDBK-299 (SH). It
Upon completion of this chapter, you should be able contains information and current data for the new
to do the following: family of low-smoke (LS) cables authorized for
shipboard use. This handbook provides information to
1. ldentify electrical cables by classification, type
supply and installation activities on the procurement and
a n d s i z e d e s i g n a t i o n , ratings, and
use of electrical shipboard cables, particular y the
characteristics.
selection of suitable substitute cables for use if the
2. Recognize the different types of deck risers, specified types and sizes aren’t immediately available.
wireways, cable supports, and installations. [t also contains information so you can select currently
3. Identify the various protective devices that available items suitable for replacement of obsolete
include relays and circuit breakers. items.
4. Recognize the purpose of and identify control For many years most of the shipboard power and
devices, to include manually and electrically lighting cables for fixed installation had silicone-
operated contacts, limit and float switches, and glass insulation, a polyvinyl chloride jacket, and
pilot control devices. aluminum armor. The construction was watertight.
5. Recognize the purpose for ground cables and The determination was made that cables with all
identify their requirements. these features were not necessary for many
applications, especially within watertight
6. Identify various plugs and cords and their safe
usage. compartments and noncritical areas above the
watertightness level.

Cables jacketed with polyvinyl chloride give off

ELECTRICAL CABLES toxic fumes and dense, impenetrable smoke when
on fire. These hazards were noticed when an
Shipboard electrical and electronic systems require electrical fire smoldered through the cable ways aboard
a large variety of electrical cables. Some circuits require a naval ship. Because of the overwhelming amount of
only a few conductors having a high current-carrying smoke and fumes, fire fighters were unable to
capacity. Other circuits require many conductors effectively control the fire, which caused a lot of
having a low current-carrying capacity. Other types of damage.
circuits may require cables with a special type of
insulation; for example, the conductors may have to be A new family of cable was designed to replace the
shielded, or, in some cases, the conductors may have to silicone-glass insulation with polyvinyl chloride jacket.
be of a metal other than copper. The new cable is constructed with a polyolefin jacket.

2-1
 jacket. The lightweight cable is covered by Military
Specification MIL-C-24640.

TYPES AND SIZE DESIGNATIONS

OF CABLES

Shipboard electrical cables are identified according

tot type and size. Type designations consist of letters to
indicate construction and/or use. Size designations
Figure 2-1.—Construction of low-smoke cable (typical). consist of a number or numbers to indicate the size of
the conductor(s) in circular mil area, number of
conductors, or number of pairs of conductors,
The new design conforms to rigid toxic and smoke (fig.
depending upon the type of cable.
2-1) indexes to effectively reduce the hazards associated
with the old design. This new family of cables is The first part of the cable designation is the type
electrically and dimensionally interchangeable with letters, such as LS for low smoke. In most cases, the
silicone-glass insulated cables of equivalent sizes. This number of conductors in a cable identification includes
cable is covered by Military Specification up to four conductors; for example, S—single
MIL-C-24643. conductor, D—double conductor, T—three conductor,
and F—four conductor. For cables with more than four
A family of lightweight cables has been introduced
conductors, the number of conductors is usually
to help eliminate excessive weight from the fleet.
indicated by a number following the type letters. In this
Considering the substantial amount of cable present on
latter case, the letter M is used to indicate multiple
a ship or submarine, a reduction in cable weight will
conductor.
impact on the overall load and improve performance and
increase efficiency. This new family of lightweight The new LS cable identification is shown in table
cables is constructed from cross-linked polyalkene and 2-1. Two examples of common shipboard cable
micapolmide insulation and a cross-linked polyolefin designations are as follows:

LSTSGU/A-9 LSTHOF-42

LS — Low smoke LS — Low smoke

T — Three conductors T — Three conductors

SG — Extruded silicone rubber and glass insulation, HO — Heat and oil-resistant

cross-linked polyolefin jacket
F — Flexible: ethylene propylene rubber
insulation, cross-linked polyolefin jacket

U — Unarmored 42 — Cross-sectional area in circular mils (column 5)

A — Armored

9 — Cross-sectional area in circular mils (column 5)

2-2
 Table 2-1.—Low-Smoke Cable Identification

You should note that there are only two changes to CLASSIFICATIONS OF
the cable designation, the LS and U/A additions to the CABLES
cable identification.

Most cables and cords contain a continuous, thin, Cables must have the ability to withstand heat, cold,
moisture-resistant marker tape directly under the cable dampness, dryness, bending crushing, vibration,
or cord binder tape or jacket at less than 1-foot intervals. twisting, and shock because of the varied service
This tape contains the following information conditions aboard ship. No one type of cable has been
1. The name and location of the manufacturer designed to meet all of these requirements; therefore, a
variety of types are used in a shipboard cable
2. The year of manufacture; the military
installation.
specification number of the cable
3. The progressive serial number. The serial Cables are classified as watertight or nonwatertight,
number is not necessarily a footage marker. A watertight or nonwatertight with circuit integrity
serial number is not repeated by a manufacturer construction, and armored or unarmored. They are
in anyone year for anyone type and size of cable further classified as being nonflexing service, flexing
or cord. service, and special purpose.

2-3
 Look at table 2-2, which shows the various has circuit integrity, vital circuits remain energized
classifications for cables used in power, lighting, longer, allowing you to setup alternate sources of power.
control, electronic, and communication and
instrumentation applications. Armored Cable

Watertight Cable The term armored cable refers to a cable that has an
outer shield of weaved braid. The braid is made of
The term watertight cable indicates standard cable aluminum or steel and applied around the impervious
in which all spaces under the impervious sheath are sheath of the cable. This weaved braid serves only as
filled with material. This eliminates voids and prevents physical protection for the vinyl cable jacket during the
the flow of water through the cable by hose action if an initial installation of the cable. Thereafter, it serves no
open end of cable is exposed to water under pressure. useful purpose.

Circuit Integrity Nonflexing Service Cable

The term circuit integrity indicates the cable has Nonflexing service cable, designed for use aboard
been constructed in such a way as to provide added ship, is intended for permanent installation, Cables used
protection that will allow it to function for a longer with lighting and power circuits are intended for
period of time while under fire conditions. Because it nonflexing service. Nonflexing service can be further

Table 2-2.—Cable Classifications

2-4
classified according to its application and is of two Repeated flexing service cable designed for general
types—general use and special use. use is of four different types, depending on the number
of conductors. This type cable is available in various
GENERAL USE.— Nonflexing service cable can
conductor sizes and designated:
be used in nearly all parts of electric distribution
systems, including the common telephone circuits and • LSSHOF (single conductor)
most propulsion circuits. Special cases occur in dc • LSDHOF (two conductor)
propulsion circuits for surface ships. In those cases
where the impressed voltage is less than 1,000 volts, an • LSTHOF (three conductor)
exception is permitted. • LSFHOF (four conductor)
LSDSGA (low-smoke, two-conductor, silicone SPECIAL USE.— There are many different types
rubber and glass-braided insulation, cross-linked of flexing service cable designed for special
polyolefin jacket, armored)is one type of cable usually requirements of certain installations, including those
found in this general use, nonflexing service. Also in this used in communications lines (LSTTOP) and casualty
classification is LSMSCA (low-smoke, multiconductor, power cables (LSTHOF). TRF cable is used for
silicone rubber insulated-glass braided conductors, arc-welding circuits.
cross-linked polyolefin jacket, armored). This cable is
RADIO-FREQUENCY COAXIAL CABLES
nothing more than watertight cable used in interior
communications, as well as in fire control circuits. Radio-frequency (RF) cables may look like power
SPECIAL USE.— There are many shipboard cables, but they require special handling and careful
electrical circuits that have special requirements for installation. RF cables are vital to the proper operation
of all electronic equipment. They must be installed and
voltage, current, frequency, and service. These
maintained with the greatest care. The following is an
requirements must be met in cable installation. There
example of a common RF cable having the properties
are also other circuits where general-use, nonflexing
shown below:
service cable may meet the necessary requirements but
be economical y impracticable. For these reasons, there LSTTRSU/A The following is an example of the
are many different types of nonflexing service cable for properties of a common radio-frequency cable:
specialized use, such as degaussing, telephone, radio, LS — Low smoke
and casualty power. For example, LSMDU cable is a
TT — Twisted pairs
multiconductor cable used in degaussing circuits.
LSTCJA cable consists of one conductor of constantan R — Radio
(red) and one conductor of iron (gray), and is used for S — Shielded flexible, cross-linked polyethylene
pyrometer base leads. insulation, braided shield for each pair, cross-
linked polyolefin jacket
Flexing Service Cable U — Unarmored
A — Armored
Flexing service cable designed for use aboard ship
is commonly referred to as being portable. It is Flexible RF transmission lines (coax) are
two-conductor cables. One conductor is concentrically
principally used as leads to portable electric equipment.
contained within the other as shown in figure 2-2. Both
There are two types of flexing service cable—general
use and special use.

GENERAL USE.— Repeated flexing service cable

is used as leads to portable electric equipment and
permanently installed equipment in places where cables
are subjected to repeated bending, twisting, mechanical
abrasion, oil, sunlight, or where maximum resistance to
moisture is required. Its letter designation is LSHOF
(low smoke, heat and oil resistant, flexible). Figure 2-2—Construction of flexible RF transmission line.

2-5
conductors are essential for efficient operation of the Two-conductor cable should be installed for
transmission line. The proper connectors and two-wire, dc and single-phase, ac circuits.
terminations are also necessary for efficient operation Three-conductor cable should be installed for
three-wire, dc, or three-phase, ac circuits.
of the line.
Four-conductor cable should be installed
The inner conductor maybe either solid or stranded. where two two-wire lighting circuits are run in
It may be made of unplated copper, timed copper, or the same cable. Four-conductor and multi-
silver-plated copper. Special alloys may be used for conductor cable should be installed for con-
special cables. trol circuits and communications circuits as
necessary.
The dielectric insulating material is usually
polyethylene or TeflonTM. To select the proper size cable for a particular
installation, you must know the following:
• Polyethylene is a gray, translucent material.
• The total connected load current
Although it is tough under general usage, it will
flow when subjected to heavy pressure for a • The demand factor
period of time.
• The allowable voltage drop
• TeflonTM is a white opaque plastic material that
To compute the total connected load current
withstands high temperatures and remains for dc power circuits, you add the sum of the rated
flexible at relatively low temperatures. It current of the connected loads as listed on the
has a peculiar quality in that nothing will identification plates of connected motors and
stick to it. Also, it is unaffected by the usual appliances. Add an additional 100 watts for each
solvents. receptacle not specifically indicated. To
compute the total connected load current for
Braided copper is usually used for the outer
ac power circuits, add the connected load
conductor, and it may be tinned, silver plated, or bare. current of the connected motors and appliances
The outer conductor is chosen to give the best electrical vectorially.
qualities consistent with maximum flexibility.
The demand factor of a circuit is the ratio of the
The protective insulating jacket is usually a maximum load averaged for a 15-minute period to the
synthetic plastic material (vinyl resin). Neoprene total connected load on the cable. If you cannot
rubber is generally used on pulse cable; silicone determine the feeder demand factor for a group of loads,
rubber jackets are used for high-temperature you may assume a value of 0.9. For power systems
applications. supplying a single-phase load or for a lighting system
branch, submain, and main circuits, the demand factor
Armor is needed for protection. It may be braided is unity.
aluminum, or sometimes galvanized steel, similar to that
The voltage drop (difference in voltage
used on power cables.
between any two points in a circuit) is expressed
as a percentage of the rated switchboard (or
SELECTING CABLE switchgear group) bus voltage or the transformer
nominal voltage. The maximum percentage of
voltage drop allowed for a circuit is specified
When selecting cable, use all reference data
by the Naval Sea Systems Command and
available. Electrical cables installed aboard Navy
varies according to the intended service of the
vessels must meet certain requirements determined by
circuit.
the Naval Sea Systems Command These requirements,
published in the General Specifications for Ships of the
U.S. Navy ( N A V S E A S 9 A A 0 - A A - S P N - 0 1 0 / CABLE INSTALLATION
GEN.SPEC), are too numerous to cover in detail in this
TRAMAN; therefore, only the more basic requirements EMs install cable whenever necessary to repair
are included. damage or to accomplish authorized ship alterations

2-6
(SHIPALTs). Before work is begun on a new cable • Because attenuation (power loss) in a line
installation, cableway plans should be available. If increases with its length, keep cables as short as
repairs to a damaged section of installed cable practicable. With the use of short lengths of cable,
are to be made, information on the original high-temperature locations, sharp bends, and strain on
installation can be obtained from the plans the cable can be avoided.
of the ship’s electrical system. These plans
• Keep the number of connectors to a minimum to
are normally on file in the engineering department
reduce line losses and maintenance problems.
office (legroom) aboard ship. If a ship alteration
is to be accomplished, applicable plans not Flexible cables are flexible only in the sense that
already on board can be obtained from they will assume a relatively long bend radius. They are
the naval shipyard listed on the authorization not intended to be stretched, compressed, or twisted;
for the SHIPALT at the planning yard for the they are to be installed with this in mind. The flexibility
ship. of cables can be expressed by their minimum bend
radius.

Installing the Cables The measurement point for minimum radius of

bend should be that surface of the cable that is on
the innermost portion of the cable bend. Dimensions
Before installing new cable, you should survey listed in the C a b l e C o m p a r i s o n H a n d b o o k
the area to see if there are spare cables in existing (MIL-HDBK-299(SH)) are approximately 8 times
wireways and spare stuffing tubes that can be the overall diameter of the cable or cord. During
used in the new installation. The following the installation process, the minimum radius
considerations should be made when planning the cable should be about 12 times the cable diameter for
run: conduit bends, sheaves, and other curved surfaces
around which the cable or cord may be pulled under
• Locate the cable so damage from battle will tension.
be minimized, to include running cables along
different well-separated paths to reduce the Fabricated straps are used for holding the cables.
probability of battle damage to several cables They are snug, but not too tight. Back straps (used
simultaneously. to keep the cable away from a surface) are used for
cable runs along masts or in compartments that are
• Locate the cable run so physical and electrical subject to sweating. In more recent installations,
interference with other equipment and cables will be semicontour straps and cable bands are used for certain
avoided applications.
• Locate the cable so maximum dissipation of The exact methods that you should use to
internally generated heat will occur. install cables are included in the Electronics Installation
and Maintenance Book, NAVSEA 0967-000-0110.
• Do not run cables on the exterior of
The Cable Comparison Guide, N A V S E A
the deckhouse or similar structures above the
0981-052-8090, contains information about all types of
main deck, except where necessary because of the
electrical shipboard cable that was installed before
location of the equipment served, structural
1986.
interferences, or to avoid hazardous conditions or
locations. For elementary and isometric blueprints of ship’s
electrical cable wiring diagrams, their care and stowage,
• Where practicable, route vital cables along
and the correction of blueprints after modification of
the inboard side of beams or other structural
their circuits, refer to Blueprint Reading and Sketching,
members. This location will give maximum protection
NAVEDTRA 12014.
against damage by flying splinters or machine-gun
strafing.
Cable Ends
• When running cables, avoid possible
high-temperature locations, if possible.
When connecting a newly installed cable to a unit
• Run pulse cables separately, when possible, to of electrical equipment, the first thing you should
reduce coupling and interference. determine is the proper length of the cable. Then, you

2-7
remove the armor (if installed) and impervious sheath,
trim the cable, and finish the end.
1. Determine the correct length by using the
following procedure:

• Form the cable run from the last cable support

to the equipment by hand. Allow sufficient slack and
bend radius to permit repairs without renewal of the
cable.

• Carefully estimate where the armor, if

applicable, on the cable will have to be cut to fit the
stuffing tube (or connector) and mark the location with
apiece of friction tape. Besides serving as a marker, the
tape will prevent unraveling and hold the armor in place
during cutting operations.
Figure 24.—Representative nylon stuffing tube installations.
• Determine the length of the cable inside the
equipment, using the friction tape as a starting point. the armor terminates. Use the cable stripper for this job.
Whether the conductors go directly to a connection or Do not take a deep cut because the conductor insulation
form a laced cable with breakoffs, carefully estimate the
can be easily damaged. Flexing the cable will help
length of the longest conductor. Then add
separate the sheath after the cut has been made. Clean
approximately 2 1/2 times its length, and mark this
position with friction tape. The extra cable length will any paint from the surface of the remaining impervious
allow for mistakes in attaching terminal lugs and sheath exposed by the removal of the armor (this paint
possible rerouting of the conductors inside the will conduct electricity).
equipment. You now know the length of the cable and 4. Once the sheath has been removed, trim the
can cut it.
cable filler with a pair of diagonal cutters.
2. Next the armor, if installed, must be removed.
5. There are several methods for finishing and
Use a cable stripper of the type shown in figure 2-3. Be
protecting cable.
careful not to cut or puncture the cable sheath where the
sheath will contact the rubber grommet of the nylon • The proper method for finishing and
stuffing tube (fig. 2-4). The uses and construction of protecting cable ends not requiring end sealing is shown
stuffing tubes will be described later in this chapter. in figure 2-5. For cables entering enclosed equipment
3. Remove the impervious sheath, starting a (such as connection boxes, outlet boxes, fixtures, etc.),
distance of at least 1 1/4 inches (or as necessary to fit use the method shown in figure 2-5, view A.
the requirements of the nylon stuffing tube) from where
• An alternate method (when synthetic resin
tubing is not readily obtainable) is to apply a coat of
air-drying insulation varnish to the insulation of each
conductor as well as to the crotch of the cable. The end
of the insulation on each conductor is reinforced and
served with treated glass cord, colored to indicate proper
phase marking.

• For watertight cables entering open

equipment (such as switchboards), use the method
shown in figure 2-5, view B. An alternate method is
shown in figure 2-5, view C.

• For nonwatertight cables entering open

equipment, use the methods as shown in figure 2-5,
Figure 2-3.—Cable stripper. views D and E.

2-8
Figure 2-5.—Protecting cable ends.

2-9
Figure 2-5.—Protecting cable ends—Continued.

2-10
 equipment in which electrical clearances would be
reduced below minimum standards require solder
terminals.
For connection under a screwhead where a
standard terminal is not practicable, you can
use an alternate method. Bare the conductor for the
required distance and thoroughly clean the strands.
Then twist the strands tightly together, bend them
around a mandrel to form a suitable size loop (or
hook where the screw is not removable), and dip the
prepared end into solder. Remove the end, remove
the excess solder, and allow it to cool before connecting
it.

After the wiring installation has been completed,

measure the insulation resistance of the wiring
circuit with a Megger or similar (0- to 100-megohm,
500-volt dc) insulation resistance measuring
instrument. Do not energize a newly installed, repaired,
or modified wiring circuit without making sure (by
Figure 2-6.—Wire strippers. insulation tests) that the circuit is free of short circuits
and grounds.

Small refrigerators, drinking fountains, and

Conductor Ends coffee makers are plugged into receptacles
connected directly to the ship’s wiring. To
Wire strippers (fig. 2-6) are used to strip insulation remove stress from the equipment terminal
from the conductors. You must be careful not to nick block and its connected wiring, rigidly clamp
the conductor stranding while removing the insulation. the cable to the frame of the equipment close
Do not use side or diagonal cutters for stripping to the point where the cable enters the equip-
insulation from conductors. ment.
Thoroughly clean conductor surfaces before
applying the terminals. After baring the conductor Conductor Identification
end for a length equal to the length of the terminal
barrel, clean the individual strands thoroughly
Each terminal and connection of rotating ac and dc
and twist them tightly together. Solder them to form a
neat, solid terminal for fitting either approved clamp equipment, controllers, and transformers is marked with
lugs or solder terminals. If the solder terminal is standard designations. This is done with synthetic resin
used, tin the terminal barrel and clamp it tightly over tubing or fiber wire markers located as close as
the prepared conductor (before soldering) to practicable to equipment terminals, with fiber tags near
provide a solid mechanical joint. You do not need to the end of each conductor, or with a stamp on the
solder conductor ends for use with solderless terminals.
terminals applied with a crimping tool. Don’t use
a side or diagonal cutter for crimping solderless Individual conductors may also be identified
terminals. by a system of color coding. Color coding
of individual conductors in multi conductor
Solderless terminals may be used for lighting,
power, interior communications, and fire control cable is done according to the color coding tables
applications. However, equipment provided with solder contained in Naval Ships’ Technical Manual, Chapter
terminals by the manufacturer and wiring boxes or 320.

2-11
 The color coding of conductors in power and light Letters used to designate the different services are
cables is shown in table 2-3. Neutral polarity,(±), where shown in table 2-4.
it exists, is always identified by the white conductor.
Voltages below 100 volts are designated by the
actual voltage, for example, 24 for a 24-volt circuit. The
Cable Markings number “1” is used to indicate voltages between 100 and
199; “2” for voltages between 200 and 299; “4” for
Metal tags embossed with the cable designation are voltages between 400 and 499; and so on. For a three
used to identify all permanently installed shipboard wire (120/240), dc system or a three-wire, three-phase
electrical cables. These tags, when properly applied, system, the number used indicates the higher voltage.
make it easy to identify cables for maintenance and
The destination of cables beyond panels and
replacement purposes.
switchboards is not designated except that each circuit
The marking system for power and lighting cables alternately receives a letter, a number, a letter, and so on
consists of three parts in sequence: source, voltage, and progressively, each time it is fused. The destination of
service. Where practical, the destination of the cable is power cables to power consuming equipment is not
shown as well. Each of the parts are separated by
Table 2-4.—Cable service designation letters
hyphens.
Table 2-3.—Color Code for Power and Lighting Cable
Conductor

2-12
 Figure 2-7.—Cable tag. Figure 2-8.—A lacing shuttle.

designated except that each cable receives a single-letter The most common lacing material is waxed cord.
alphabetical designation, beginning with the letter A. The amount of cord required to single lace a group of
conductors is approximately 2 1/2 times the length of
Where two cables of the same power or lighting
the longest conductor in the group. Twice this amount
circuit are connected in a distribution panel or terminal
is required if the conductors are to be double laced.
box, the circuit classification is not changed. However,
the cable markings have a suffix number (in Normally, conductors are laid out straight and
parentheses) indicating the cable section. For example, parallel to each other before to lacing since this makes
(4-168-1)4P-A(1) (fig. 2-7) identifies a 450 volt power conductor lacing and tracing easier. However, some
cable supplied from a distribution panel on the fourth installations require the use of twisted wires. One
deck at frame 168 starboard. The letter A indicates that example of a twisted wire installation is the use of
this is the first cable from the panel, and the (1) indicates twisted pairs for the ac filament leads of certain electron
that it is the first section of a power main with more than tube amplifiers. This reduces the effect of radiation of
one section. their magnetic field and helps to prevent annoying hums
in the amplifier output. When you replace any wiring
The power cables between generators and
harness, duplicate the original layout.
switchboards are labeled according to the generator
designation. When only one generator supplies power A shuttle on which the cord can be wound will keep
to a switchboard, the generator will have the same num- the cord from fouling during the lacing operations. A
ber as the switchboard plus the letter G. Therefore, you shuttle similar to the one shown in figure 2-8 may easily
know that 1SG denotes one ship service generator that be fashioned from aluminum, brass, fiber, or plastic
supplies power to 1S switchboard. When more than one scrap. The edges of the material used for the shuttle
generator supplies power to a switchboard, the first gen- should be smoothed to prevent injury to the operator and
erator (determined by the general rule for numbering damage to the cord. To fill the shuttle for single lace,
machinery) will have the letter A immediately following measure the cord, cut it, and wind it on the shuttle.
the designation; the second generator that supplies power Double lacing is done like single lacing, except that the
will have the letter B following the designation; and so length of the cord before winding it on the shuttle is
on. Therefore, 1SGA and 1SGB denote two ship service doubled. Also, start the ends on the shuttle to leave a
generators that supply ship service switchboard 1S. loop for starting the lace.
Lacing Conductors Before starting, terminating, and splicing knots,
apply a binder such as GLYPTOL to the knots.
Conductors within equipment must be kept in place
to present a neat appearance and to make it easier to trace Start the single lacing procedure by using a clove
conductors when alterations or repairs are required. hitch, with an overhand knot tied over the clove hitch
When conductors are properly laced, they support each (fig. 2-9, view A). Lockstitch lacing is shown in (fig.
other and form a neat, single cable. 2-9, view B). The cable is laced its entire length using

Figure 2-9.—Lacing procedure.

2-13
the lockstitch as shown in (fig. 2-9, view C). The lacing
is terminated with two lockstitches. Use the same
procedure when using a double wrap of lacing twine.
Place lockstitching immediately next to and on both
sides of breakouts that are to be laced. Anchor the lacing
of auxiliary lines and final breakouts to the main section
by passing the lacing twine through the two lockstitches
on the main section and then using the starting hitch and
knot (fig. 2-9, view A).

On cable sections 5/8 inch or smaller in diameter,

the space between the lockstiches must be 1/2 inch to
3/4 inch On cable sections larger than 5/8 inch in
diameter, the spacing must be 1/2 inch to 1 inch. On
cable sections larger than 5/8 inch in diameter, use a
double wrap of lacing.

Double lace is applied in a reamer similar to single Figure 2-11.—The loop method of terminating the lace.
lace, except that it is started with the telephone hitch and
is double throughout the length of the lacing (fig. 2-10). Lace the spare conductors of a multiconductor cable
You can terminate double as well as single lace by separately. Then secure them to active conductors of the
forming a loop from a separate length of cord and using cable with a few telephone hitches. When two or more
it to pull the end of the lacing back underneath a seining cables enter an enclosure, lace each cable group
of about eight turns (fig. 2-11). separately. When groups parallel each other, bind them
together at intervals with telephone hitches (fig. 2-12).

You should serve conductor ends (3,000 cm or

larger) with cord to prevent fraying of the insulation (fig.
2-13). When conductor ends are served with glass cord
colored for phase marking, make sure that the color of
the cord matches the color of the conductor insulation

CABLE MAINTENANCE

The primary purpose of electrical cable

maintenance is to preserve the insulation resistance. To
preserve the insulation resistance, you must know the
characteristics of the insulating materials used in naval
shipboard electrical equipment. You must also know the
factors that affect insulation resistance.

Figure 2-10.—Starting double lace with the telephone hitch. Figure 2-12.—Binding cable groups with the telephone hitch.

2-14
 The purpose of assigning each material a definite
temperature index is to make it easier to compare
materials and to provide a single designation of
temperature capability for purposes of standardization.
Some of the classes of insulation are discussed in this
section.

Class O insulation. Class O insulation consists of

cotton, silk, paper, and similar organic materials that are
not impregnated or immersed in a liquid dielectric.
Figure 2-13.—Serving conductor ends. Class O insulation is seldom used by itself in electrical
equipment.
Insulation
Class A insulation. Class A insulation consists of
the following:
Their are two purposes of insulation on electric
cables and equipment: 1. Cotton, paper, and similar organic materials
when they are impregnated or immersed in a
1. To isolate current-carrying conductors from
liquid dielectric
electrically conductive structural parts
2. Molded and laminated materials with cellulose
2. To insulate points of unequal potential on
filler, phenolic resins, and other resins of similar
conductors from each other.
properties
Normally, the conductivity of the insulation should be
3. Films and sheets of cellulose acetate and other
sufficient y low to result in negligible current flow
cellulose derivatives of similar properties
through or over the surface of the insulation.
4. Varnish (enamel), as applied to conductors.
Electrical insulating materials used in naval
shipboard electrical equipment (including cables) are Class B insulation. Class B insulation consists of
classified according to their temperature indexes. The mica, asbestos, fiber glass, and similar inorganic
temperature index of a material is related to the materials in built-up form with organic binding
temperature at which the material will provide a substances.
specified life as determined by test, or as estimated from
service experience. To provide continuity with past Class H insulation. Class H insulation consists the
procedures, the preferred temperature indexes given in following:
table 2-5 are used for insulating materials that, by test
or experience, fall within the temperature ranges 1. Mica, asbestos, fiberglass, and similar inorganic
indicated. materials in built-up form with binding
substances composed of silicone compounds or
Table 2-5.—Temperature Indexes of Insulating Materials materials with equivalent properties; and
2. Silicone compounds in the rubbery or resinous
forms, or materials with equivalent properties.
Class C insulation. Class C insulation consists
entirely of tics, glass, quartz, and similar inorganic
material. Class C materials, like class O, are seldom
used alone in electrical equipment.

Class E insulation. Class E insulations an extruded

silicone rubber dielectric used in reduced-diameter
electric cables in sizes 3, 4, and 9. Special care should
be exercised in handling the cables to avoid sharp bends
and kinks that can damage the silicone rubber insulation
on the old types that did not employ a nylon jacket over
each insulated conductor.

2-15
 Class T insulation. Class T insulation is a silicone insulation limiting temperature and the sum of the
rubber treated glass tape. It is also used in ambient and temperature rise temperatures is the
reduced-diameter cables in sizes 14 through 2000. additional temperature allowed for the hot-spot
temperature.
For an idea of some insulation uses, look at the table
shown below: The ultimate temperature rise of electrical
equipment is reached when the rate at which heat is
developed equals the rate at which heat is transferred to
the surrounding atmosphere. The heat developed by
electrical equipment can usually be accurately
measured. However, the temperature of the immediate
surrounding area (ambient temperature) can become
critical to the equipment if proper ventilation is not
maintained.

The maximum allowable temperature rise and the

design ambient temperature allowed for electrical
equipment are usually shown on equipment nameplates,
on equipment drawings, and in technical manuals for
specific equipment. When information is not available
from these sources, refer to NSTM, chapter 300, for
information on the maximum permissible temperature
rises.

The engineering design of ships takes into account

the relationship of cable sizes and resistances with the
cable load currents and temperatures.

Insulation Resistance Measurements.

Temperature Effects on Insulation.

Very high temperatures that produce actual burning The insulation resistance of shipboard electrical
or charring may destroy insulation in a few seconds. It cable must be measured periodically with an
is important to maintain operating temperatures of insulation-resistance-measuring instrument (Megger)
electrical equipment within their designed values to to determine the condition of the cable. Measurements
avoid premature failure of insulation Temperatures
Table 2-6.—Limiting Temperature of Insulation systems
only slightly in excess of designed values may produce
gradual deterioration, which, though not immediately
apparent, shortens the life of the insulation. As a rule of
thumb, thermal aging will cause the life of insulation
will decrease by 1/2 for every 10° to 15°C increase in
the operating temperature above the rated temperature
for the insulation class.
Insulation system classes are designated by letters,
numbers, or other symbols and may be defined as
assemblies of insulation materials in association with
equipment parts. Table 2-6 shows the insulation system
classification used for Navy electrical equipment based
on limiting temperatures. The limiting temperatures of
an insulation system may be established by test or by
service, and depend on an observable temperature rise
of the equipment, design ambient temperature, and
hot-spot temperature. The difference between the

2-16
should be made on each individual leg of dc circuits and removed from the outlets (fig. 2-14). If local lighting
each individual phase lead of three-phase ac circuits. switches are double pole, the insulation resistance of the
local branch circuit will not be measured when the
For lighting circuits, the legs or phase leads should switch is open. In such cases, making an insulation test
include all panel wiring, terminals, connection boxes, from one leg or phase lead to ground with the local
fittings, fixtures, and outlets normally connected. The switches closed will determine whether grounds exist
lights should be turned off at their switches and all plugs on the circuits and fixtures.

Figure 2-14.—Measuring insulation resistance of a lighting circuit.

2-17
 Figure 2-15.—Measuring insulation resistance of a power circuit.

In power circuits (fig. 2-15), include the legs or de-energized in a warm ambient, and 40°F if it is
phase leads, panel wiring terminals, connection boxes, de-energized in a cold ambient.
fittings, and outlets (plugs removed).
Look at figure 2-17, which shows a nonograph for
For degaussing circuits, you should take obtaining resistance per foot. Select the point of
measurements at a degaussing coil connection box; allowable resistance per foot based on the ambient
include in the legs measured the coil cables, through condition and the type of cable. Using the nomograph,
boxes, and feeder cables. Disconnect the supply and draw a straight line from the measured insulation
control equipment by opening the circuit on the coil side resistance to the length of cable. The line should cross
of the control equipment. Measure the the resistance per foot line above the selected minimum
compass-compensating coil feeder cable with all control resistance per foot point. Corrective action is required
equipment disconnected. Additional information on if the resistance per foot is less than the selected point.
tests of degaussing installations is obtained in NSTM,
chapter 475, and in the degaussing folder furnished with
each degaussing installation.

As you use the table, refer to figure 2-16. You

should make measurements of the lighting, power, and
degaussing circuits as shown in table 2-7.

These resistance measurements are considered

satisfactory if they are not less than 1 megohm for each
complete power circuit or at least 0.5 megohm for each
complete lighting circuit. Circuits that have been
de-energized for at least 4 hours are classed as either
warm ambient or cold ambient.

NOTE: A warm ambient is defined as a warm

climate or a condition in which the entire cable is in a
heated space and not in contact with the ship’s hull. A
cold ambient is defined as a cold climate or a condition
in which most of the cable is in an unheated space or is
against the ship’s hull in cold waters.

The cable temperature should be considered to be 104°F

if the cable has been energized for 4 hours, 70°F if it is Figure 2-16.—Measuring circuit insulation resistance.

2-18
 Table 2-7.—Measuring Circuit Insulation Resistance

You need to remember mind that you cannot use a components under test contain a large electrical
400-volt dc Megger to check insulation resistance on capacity, the megohmmeter READ button must be
circuits where semiconductor control devices are depressed for a sufficient time to allow its capacitor to
involved. You should use an electron tube charge before a steady reading is obtained. The test
megohmmeter to check insulation resistance on circuits voltage applied by the megohmmeter to an unknown
and components where the insulation resistance must be resistance is approximately 50 volts when resistances of
checked at a much lower potential. The megohmmeter approximately 10 megohms are measured and slightly
operates on internal batteries. When circuits or greater than this when higher resistances are measured.

Figure 2-17.—Nomograph for obtaining resistance per foot.

2-19
 Figure 2-18.—Casualty power cable—old method of serving.

Cable Repairs equipment if the installed distribution system is

damaged.
A cable repair is the restoration of the cable armor Portable casualty power cables are type
or the outermost sheath or both. Cable repair may be LSTHOF-42. They are capable of carrying 93 A at 40°C
made by ship’s force. However, cable repair should be and 86 A at 50°C indefinitely. They have a casualty
made according to DOD-STD-2003(NAVY), unless
power application of 200 A. Metal tags installed on the
standard methods cannot be applied.
cables designate their proper lengths and locations.

On older ships, the portable cable ends are marked

Cable Splicing
to identify the A, B, and C phases visually or by touch
when illumination is insufficient for visual
A cable splice is the restoration on any part of a cable
identification. Phase A is color-coded black and has one
that cannot be restored by a cable repair. Cable splices
serving on the conductor end; phase B is color-coded
should be made according to methods described in
white and has two servings; and phase C is red with three
DOD-STD-2003(NAVY), unless standard methods
servings (fig. 2-18).
cannot be applied. Cable splices should not be made by
ship’s force except in an emergency. When such splices The insulation of the individual conductors is
are made, the y should be replaced at the earliest exposed to shipboard ambient temperatures and perhaps
opportunity by a continuous length of cable or by an oil or oil fumes and accidental damage. After an
approved splice installed by a repair activity. exposure period of 5 years or more, the conductor
insulation may lose elasticity and crack when bent while
CASUALTY POWER CABLE being handled. This could happen when the casualty
power system is rigged for emergency use. The exposed
Suitable lengths of portable casualty power cables ends of the individual conductors of the casualty power
are stowed close to the locations where they may be cables should be inspected following PMS. The best
needed for making temporary connections. They are of method for determining acceptable insulation is to
suitable lengths (normally no more than 75 feet) and sharply bend all conductors by hand. If no cracks
distributed throughout the ship according to the Ship develop, the insulation is satisfactory. Refer to figures
lnformation Book. These portable cables are used to 2-19 and 2-20 as you read the following steps you should
connect one fixed terminal to another to energize vital use to repair a defective cable:

2-20
Figure 2-19.—Method of securing a copper ferrule to a conductor.

2-21
 Figure 2-20.—Casualty power cable ends.

Figure 2-21.—New method of preparing casualty power cable ends.

2-22
 Another method being used on newer ships to installation requires a shore-power station, plugs, and
prepare casualty power cable ends is shown in figure connecting cables.
2-21. The use of the plug (SYM 1049) makes marking
of the individual phases unnecessary since the keyed Shore Power Station
segment prevents improper connections.

Fixed terminals are connected to cables which Ashore-power station (fig. 2-23, view A) is located
penetrate watertight decks (riser terminals) and at or near a suitable weather deck location. Portable
bulkheads (bulkhead terminals). These cables are of cables can be attached to the weather deck location from
type LSTSGU-75. They are capable of carrying 148 A shore or a ship alongside. The same station can be used
at 40°C and 136 A at 50°C. These fixed terminals are to supply power from the ship to a ship alongside. The
marked by nameplates (fig. 2-22) indicating the terminal shore-power station has a receptacle assembly
location and the location of the other end. arrangement as shown in figure 2-23, view B. The
shore-power system is designed to handle only enough
Portable casualty power cables should be rigged power to operate necessary machinery and provide
only when required for use or for practice in rigging the illumination for habitability.
casualty power system. At all other times, they should
be stowed in the cable rack indicated on the cable tag. SHORE POWER PLUG.— A shore-power plug is
When portable casualty power cables are rigged, installed on the end of shore-power cables for ease of
connections should be made from the load to the supply making the shore-power connection. A shore-power
to avoid handling energized cables.

Casualty power cables are a very important part of

the ship’s equipment. Each year the cables and terminal
connections should be closely inspected and tested. If
you are assigned to inspect casualty power cables,
follow the step-by-step procedures listed on the
appropriate maintenance requirement card. It tells what
tools and material the job will require, safety
precautions to observe, and procedures to follow.

Refer to chapter 3 of this manual for a description

of the casualty power distribution system.

SHORE POWER

A means of supplying electrical power to a ship

from an external source is known as shore power. This

Figure 2-22.—Casualty power fixed terminal cable tag. Figure 2-23.—Shore-power station and receptacle assembly.

2-23
 Figure 2-24.—Shore-power plug.

plug is shown in figure 2-24. To avoid personnel injury CABLE REELS.— To protect cables when they
and equipment damage, carefully inspect shore-power aren’t being use, they are stowed in reels located near
cables and fittings before making shore-power the shore power station. The reels are maintained
connections. When completing the shore-power according to PMS procedures. In addition to being kept
connections, follow installation instructions, clean and dry, they must be periodically lubricated in
maintenance requirement card (MRC) procedures, and order to turn freely while removing or stowing cables.
checkoff lists cautiously. Phase-Sequence Indicator
SHORE POWER CABLES.— Shore power is A phase-sequence indicator is used when
supplied to the ship through 150-foot lengths of portable connecting shore power to your ship to verify proper
cables of type THOF-400. These cables are rated at 400
amperes each. They are constructed according to
DOD-STD-2003-2(NAVY).

Be careful when connecting or disconnecting the

shore power cables to ensure your personal safety.
Procedures for connecting and disconnecting the cables
are discussed in greater detail in chapter 3.

Figure 2-25.—Phase-squence indicator. Figure 2-26.—Nylon Stuffing tubes.

2-24
phase relationship between your ship and shore power. of the case. Clockwise rotation indicates a correct phase
An approved type of phase-sequence indicator (fig. sequence. You can stop the motor by releasing the
2-25) has a miniature, three-phase induction motor and momentary contact switch.
three leads with insulated clips attached to the ends. The
STUFFING TUBES
leads are labeled A, B, and C. The miniature motor can
be started through a momentary contact switch. This Stuffing tubes (fig. 2-26) are used to provide for the
switch is mounted in the insulated case with a switch entry of electrical cable into splashproof, spraytight,
button protruding out the front of the case to close the submersible, and explosion proof equipment enclosures.
switch. When the motor starts turning, you can tell its Cable clamps, commonly called box connectors (fig.
direction of rotation through the three ports on the front 2-27), may be used for cable entry into all other types

Figure 2-27.—Cable clamps.

2-25
of equipment enclosures. However, top entry into these This allows a single-size stuffing tube to be used for a
enclosures should be made dripproof through stuffing variety of cable sizes, and makes it possible for nine
tubes or cable clamps sealed with plastic sealer. sizes of nylon tubes to replace 23 sizes of aluminum,
steel, and brass tubes.
Uses below and above the Main Deck The nylon stuffing tube is available in two parts.
The body, O-ring, locknut, and cap comprise the tube;
Below the main deck, stuffing tubes are used to and the rubber grommet, two slip washers, and one
penetrate the following areas: bottom washer comprise the packing kit.
• Watertight decks A nylon stuffing tube that provides cable entry into
• Watertight bulkheads an equipment enclosure is applicable to both watertight
and nonwatertight enclosures (fig. 2-28, view A). Note
• Watertight portions of bulkheads that are that the tube body is inserted from inside the enclosure.
watertight only to a certain height The end of the cable armor, which will pass through the
Above the main deck, stuffing tubes have the slip washers, is wrapped with friction tape to a
following uses for cable penetrations: maximum diameter. To ensure a watertight seal, one
coat of neoprene cement is applied to the inner surface
• Watertight or airtight boundaries of the rubber grommet and to the cable sheath where it
will contact the grommet. After the cement is applied,
• Bulkheads designed to withstand a waterhead
the grommet is immediate y slipped onto the cable. You
• Portions of the bulkhead below the height of the must clean the paint from the surface of the cable sheath
sill or coaming of compartment accesses before applying the cement.

• Flametight or gastight or watertight bulkheads, Sealing plugs are available for sealing nylon
decks, or wiring trunks within turrets or gun stuffing tubes from which the cables have been
mounts
• Structures subject to sprinkling

Construction

Stuffing tubes are made of nylon, steel, brass, or

aluminum alloys. Nylon tubes have very nearly
replaced metal tubes for cable entry to equipment
enclosures. Cable penetration of bulkheads and decks
are normally of metal because of their integrity during
fires. Stuffing tubes made of metal are normally used
for cable penetration of bulkheads and decks. Nylon
stuffing tubes melt and fail to act as a barrier during a
fire.

The nylon stuffing tube is lightweight,

positive-sealing, and noncorrosive. It requires only
minimum maintenance for the preservation of
watertight integrity. The watertight seal between the
entrance to the enclosure and the nylon body of the
stuffing tube is made with a neoprene O-ring, which is
compressed by a nylon locknut. A grommet-type,
neoprene packing is compressed by a nylon cap to
accomplish a watertight seal between the body of the
tube and the cable. Two slip washers act as compression
washers on the grommet as the nylon cap of the stuffing
tube is tightened. Grommets of the same external size,
but with different sized holes for the cable, are available. Figure 2-28.—Representative nylon stuffing tube installations.

2-26
removed. The solid plug is inserted in place of the stuffing tube, should have a minimum height of 9 inches
grommet, but the slip washers are left in the tube (fig. and a maximum height of 18 inches. If the height
2-28, view B). exceeds 12 inches, a brace is necessary to ensure rigid
support. If the installation of kickpipes is required in
A grounded installation that provides for cable entry
nonwatertight decks, a conduit bushing may be used in
into an enclosure equipped with a nylon stuffing tube is
place of the stuffing tube.
shown in figure 2-29. This type of installation is
required only when radio interference tests indicate that When three or more cables pass through a deck in a
additional grounding is necessary within electronic single group, riser boxes must be used to provide
spaces. In this case, the cable armor is flared and protection against mechanical damage. Stuffing tubes
trimmed to the outside diameter of the slip washers. are mounted in the top of riser boxes required for topside
One end of the ground strap, inserted through the cap weather-deck applications. For cable passage through
and one washer, is flared and trimmed to the outside watertight decks inside a vessel, the riser box may cover
diameter of the washers. Contact between the armor the stuffing tubes if it is fitted with an access plate of
and the strap is maintained by pressure of the capon the expanded metal or perforated sheet metal.
slip washers and the rubber grommet.

Aboard ship, watertight integrity is vital. Just one Wireways

improper cable installation could endanger the entire
ship. For example, if one THFA-4 cable (0.812 inch in
diameter) were to be replaced by the newer LSTSGA-4 Before you install new cable, survey the area to see
cable (0.449 inch in diameter), but the fittings passing if there are spare cables in existing wireways and spare
through a watertight bulkhead were not changed to the stuffing tubes that can be used in the new installation.
proper size, the result might be two flooded spaces if a The cable run must meet the following criteria:
collision or enemy hit occurs.
• Be located so that damage from battle will be
minimized
Deck Risers
• Be located so physical and electrical interference
Where one or two cables pass through a deck in a with other equipment and cables will be avoided
single group, kickpipes are provided to protect the
• Be located so that maximum dissipation of
cables against mechanical damage. Steel pipes are used
internally generated heat will occur.
with steel decks, and aluminum pipes with aluminum
and wooden decks. Inside edges on the ends of the pipe Where practical, you should route vital cables along
and the inside wall of the pipe must be free of burrs to the inboard side of beams or other structural members
prevent chafing of the cable. Kickpipes, including the to afford maximum protection against damage by flying
splinters or machine gun straffing. Only when
necessary, should cables be run on the exterior of the
deckhouse or similar structures above the main deck.

Avoid installing cable in locations subject to

excessive heat, if possible. Never install cables adjacent
to machinery, piping, or other hot surfaces having an
exposed surface temperature greater than 150°F. In
general, cables should not be installed where they may
be subjected to excessive moisture.

CABLE SUPPORTS

To prevent unnecessary stress and strain on cables,

cable supports or straps are used. Types of cable
supports are the single cable strap, cable rack, and
Figure 2-29.—Nylon stuffing tube grounded installation. modular cable supports.

2-27
 so forth. The one-hole cable strap (fig. 2-30, view A)
may be used for cables not exceeding five-eighths inch
in diameter. The two-hole strap (fig. 2-30, view B) may
be used for cables over five-eighths inch in diameter.
The spacing of simple cable supports, such as those
shown in figure 2-30, must not exceed 32 inches, center
to center.

Cable Rack

The cable rack is more complex than the single

cable strap. The cable rack consists of the cable hanger,
cable strap, and hanger support (fig. 2-31).

The banding material of the cable rack is 5/8 inch

wide. It may be made from zinc-coated steel,
corrosion-resistant steel, or aluminum, depending on the
requirements of the installation. For weather deck
installations, use corrosion-resistant steel with
copper-armored cables, zinc-coated steel with steel
armor, and aluminum with aluminum armor.
When applying banding material to the cable rack,
you should apply one turn of banding for a single cable
of less than 1 inch in diameter. Apply two turns of
banding for single cables of 1 inch or more in diameter
Figure 2-30.—Single cable strap application.
and for a row of cables. Apply three turns of banding
for partially loaded hangers where hanger width exceeds
Single Cable Strap
the width of a single cable or a single row of cable by
more than 1/2 inch.
The single cable strap (fig. 2-30) is the simplest
form of cable support. The cable strap is used to secure Cables must be supported so that the sag between
cables to bulkheads, decks, cable hangers, fixtures, and supports, when practical, will not exceed 1 inch. Five

Figure 2-31.—Cables installed in a cable rack.

2-28
rows of cables may be supported from an overhead in Modular insert, semicircular, grooved twin
one cable rack; two rows of cables may be supported half-blocks are matched around each cable to form a
from a bulkhead in one cable rack. As many as 16 rows single block. These grooved insert blocks, which hold
of cables may be supported in main cableways, in the cables (along with the spare insert solid blocks), fill
machinery spaces, and boiler rooms. However, not up a cable support frame.
more than one row of cables should be installed on a During modular armored cable installation (fig.
single hanger. 2-32, view B), a sealer is applied in the grooves of each
block to seal the space between the armor and cable
Modular Cable Supports
sheath, The sealer penetrates the braid and prevents air
passage under the braid. A lubricant is used when the
Modular cable supports (fig. 2-32) are installed on
blocks are installed to allow the blocks to slide easily
a number of naval ships. The modular method saves
over each other when the y are packed and compressed
over 50 percent in cable-pulling time and labor. Groups
over the cable. Stay plates are normally inserted
of cables are passed through wide opened frames instead
between every completed row to keep the blocks
of inserted individually in stuffing tubes. The times
positioned and help distribute compression evenly
are then welded into the metal bulkheads and decks for
through the frame. When a frame has been built up, a
cable runs. The modular method of supporting
compression plate is inserted and tightened until there
electrical cables from one compartment to another is
is sufficient room to insert the end packing.
designed to be tireproof and water- and airtight.
To complete the sealing of the blocks and cables,
the two bolts in the end packing are tightened evenly
until there is a slight roll of the insert material around
the end packing metal washers. This roll indicates the
insert blocks and cables are sufficiently compressed to
form a complete seal. The compression bolt is then
backed off about one-eighth of a turn.
When removing cable from modular supports, first
tighten down the compression bolt. Tightening this bolt
pushes the compression plate further into the frame to
free the split end packing. Then, remove the end
packing by loosening the two bolts that separate the
metal washers and the end packing pieces. Back off the
compression bolt, loosening the compression plate.
Then remove this plate, permitting full access to the
insert blocks and cables.

CONTROL DEVICES
A control device, in its simplest form, is an electrical
switching device that applies voltage to or removes it
from a single load. In more complex control systems,
the initial switch may set into action other control
devices that govern motor speeds, compartment
temperatures, water depth, aiming and firing guns, or
guided missile direction. In fact, all electrical systems
and equipment are controlled in some manner by one or
more controls.

MANUALLY OPERATED CONTACTS

Manually operated switches are those familiar

electrical items that can be conveniently operated with
Figure 2-32.—Modular cable supports. the hand. (NOTE: As you read this paragraph, look at

2-29
 Figure 2-33.—Manually operated contacts.

figure 2-33.) The push button (fig. 2-33) is the simplest In operation, this switch might be closed by a clutch in
form of electrical control. When the button is pushed a timer assembly. After the timer motor operates
down (view A), contact is made across the two circles through a given number of revolutions, a clutch in the
representing wire connections. When pressure is timer will release the contact, causing the switch to
released a spring (not shown) opens the contact. View reopen. The timed switches may also be shown with an
B shows a normally closed contact. When it is pressed, arrow that indicates whether the contact is timed to open
contact at the two terminals is broken. When it is or close. The direction of the arrow indicates what
relased, a spring-loaded feature (not shown) closes the condition exists.
switch again. The switch in view C is designed to make
one contact and break another when it is pressed. The LIMIT SWITCHES
upper contact is opened when the lower is closed; again,
the spring arrangement (not shown) resets the switch to
the position shown. The switch in view D is a In certain applications, the ON-OFF switch does not
maintained contact switch. When it is pressed, it hinges give enough to ensure safety of equipment or personnel.
about the center point and will stay in that position until A limit switch is incorporated in the circuit so that
the other part of the button is pressed. operating limits are not exceeded

The limit switch is installed in series with the master

ELECTRICALLY OPERATED CONTACTS switch and the voltage supply. Any action causing the
limit switch to operate will open the supply circuit.
Schematic wiring diagrams have both push-button One application of limit switches is in equipment
and electrically operated contacts. Two different that moves over a track. It is possible to apply power so
methods of control contacts are shown in figure 2-34.
that operation will continue until the carriage hits an
View A shows the normally open (NO) position that
obstruction or runs off the end of the track.
closes when operated. View B shows the normally close
(NC) position that opens when energized. Views C, D, If limit switches are installed near the end of travel,
E, and F show timer contacts. After being energized, an arm or projection placed on the moving section will
these contacts will take some time to close or open. This trip a lever (fig. 2-35) on the limit switch. The switch
time element is controlled by a timer motor, a dashpot, then opens the circuit and stops the travel of the carriage.
pneumatically, or by magnetic flux. Those devices that This type of control is a direct-acting, lever-controlled
are timed closed or open have the following indications limit switch. Another type, an intermittent gear drive
at the lower contacts: TC (timed closed), TO (timed limit switch, may be coupled to a motor shaft to stop
open), and TO ENERGIZE (while this contact is already action when a definite number of shaft revolutions is
shown open, before it can be timed open, it must close). completed.

Figure 2-34.—Electrically operated contacts.

2-30
 FLOAT SWITCHES

Float switches are used to control electrically driven

pumps and regulate liquid levels in tanks.

Construction

In a tank installation (fig. 2-36), the deck and

overhead flanges are welded to the deck and overhead
of the tank. The float guide rod, E, fits into the bottom
flange and extends through the top flange. The float
guide rod then passes through an opening in the switch
operating arm. Collars A and B on the guide rod exert
upward or downward pressure on the operating arm as
the float approaches minimum or maximum depth
positions. The switch operating arm is fastened to the
Figure 2-35.—A limit switch, roller actuator arm operated. shaft, which is coupled to the switch contact mechanism

Figure 2-36.—A float switch tank installation.

2-31
 applied to the circuit, never clean the contacts or apply
lubricants to the contact surfaces.

PRESSURE AND TEMPERATURE

SWITCHES

Pressure and temperature controls have been

grouped together because the switching mechanism is
the same for both controls; the difference is in the
operation.
Figure 2-37.—A float switch mechanism.
Pressure-controlled switches (fig. 2-38) are
operated by changes in pressure in an enclosure such as
(fig. 2-37). Collars C and D on the guide rod are held
a tank. On the other hand, temperature-controlled
in position by setscrews so that their positions can be
switches operate from changes in temperature that take
changed to set the operating levels to the desired
place in an enclosure or the air surrounding the
positions.
temperature-sensing element. Actually, both switches
As the float goes up and down, corresponding to the are operated by changes in pressure. The temperature
liquid level, it does not move the operating red, E, until element is arranged so that changes in temperature cause
contact is made with either collar. When the float comes a change in the internal pressure of a sealed-gas or
in contact with either collar, the external operating arm air-filled bulb or helix, which is connected to the
of the switch is moved and the switch is operated. actuating device by a small tube or pipe. Temperature
changes cause a change in the volume of the sealed-in
Although the switch assembly is of rugged gas, which causes movement of a diaphragm. The
construction, it must be checked regularly for proper movement is transmitted by a plunger to the switch arm.
performance.
The moving contact is on the arm. A fixed contact may
be arranged so that the switch will open or close on a
temperature rise.
Maintenance
When the switch is used to control pressure, the
temperature element is replaced by a tube that leads to
You should ensure that the switch contacts are kept
the pressure tank. The pressure inside the tank then
in good electrical condition. Determine the kind of
operates the switch mechanism.
metal used for the contacts, whether copper or silver,
and apply the maintenance procedures outlined in Naval Pressure or temperature controls may be used as a
Ship’s technical Manual, chapter 300. While power is pilot device (fig. 2-39). The circuit operation is exactly

Figure 2-38.—A representative pilot device control circuit.

2-32
 Table 2-8.—Steps to adjust pressure operated switches

STEP ACTION

1 Turn the differential adjustment screw (fig.

2-39) counterclockwise against the stop for
minimum differential.
2 Bring the system pressure to that at which
you wish the switch to close.
3 IF THEN

Contacts are open Turn the range screw

when the desired slowly clockwise
temperature is until the contacts just
reached. close.
Contacts are closed Turn the range screw
when the desired slowly
temperature is counterclockwise
Figure 2-39.—A pressure-operated switch. reached. until the contacts
open; then clockwise
until they just close.
the same regardless of the kind of pilot device 4 Bring the system to the pressure at which
used to control the circuit. To maintain more or you wish the switch to open.
less constant temperature or pressure, switch 5 Turn the differential adjustment screw
contacts are arranged to close when the pressure slowly clockwise to widen the differential
or temperature drops to a predetermined value until the desired opening pressure is
obtained.
and to open when the pressure or temperature
rises to the desired value. The reverse action
can be obtained by a change in the contact Thermal Unit Type
positions.
The bulb and helix units can be connected to the
The difference in pressure for contact opening and switch section (fig. 2-40). The bulb unit (fig. 2-40, view
closing is the differential. The switch mechanism has a
built-in differential adjustment so that the differential
can be varied over a small range. Once set, the
differential remains essential y constant at all pressure
settings.

Each switch has a range adjustment that sets

the point at which the circuit is closed. Changing
the range adjustment raises or lowers both the
closing and opening points without changing the
differential.

Adjustments

The following table describes the steps in adjusting

pressure operated switches (table 2-8);

Figure 2-40.—Thermal units.

2-33
A) is normally used when liquid temperatures are to be Table 2-9.—Manual Operation of Pilot Control Circuit
controlled. However, it may control air or gas
temperatures, provided the circulation around it is rapid
and the temperature changes at a slow rate.
The helical unit (fig. 2-40, view B) has been
specifically y designed for air and gas temperature control
circuits. To be most effective, the thermal unit must be
located at a point of unrestricted circulation so it can
“feel” the average temperature of the substance that is
to be controlled.

Some switches are stamped WIDE DIF-

FERENTIAL. They are adjusted in the same manner
described for the regular controls. However, because of The following table describes the sequence of
slight design changes, it is possible to get wider variation events during the automatic operation of the circuit in
in differential settings. table 2-10.
Table 2-10.—Automatic Operation of Pilot Control Circuit
Maintenance
When adjusting temperature controls, allow several
minutes for the thermal unit to reach the temperatures
of the surrounding air, gas, or liquid before setting the
operating adjustments. After adjusting the operating
range of pressure or temperature controls, check the
operation through at least one complete cycle. If you
find variation from the desired operating values, go
through the entire procedure again and observe
operation through a complete cycle.

PILOT CONTROL DEVICES

A pilot is defined as a director or guide of another
thing (or person). You may be familiar with ship pilots,
pilot rudders, and pilot flames. In this text, a pilot is a
small device that controls a relative] y larger device or
mechanism, usually doing so by electrical means. The
previously described float switch and pressure-operated
switches are representative examples of such pilot
devices. Pilot devices are limited in their ability to
handle large currents and voltage required to operate PROTECTIVE DEVICES
shipboard motors or power-handling units. Therefore,
it is customary for a pilot device to actuate only a Protective devices allow normal operation of
magnetic switch. The magnetic switch can be chosen circuits to continue unhampered. Once something goes
with characteristics suitable for handling the desired wrong in the circuit, protective devices will de-energize
amount of power in the motor circuit. the circuit to minimize of prevent damage to equipment
and ensure the safety of personnel. A thorough
Float switches used as pilot devices control the knowledge of protective devices will help you isolate
pump operation through other controls. A typical troubles in circuits, find the cause of interruption, clear
control circuit is shown in figure 2-38. the trouble, and restore operation with minimum loss of
time.
Switch S 1 makes it possible to have either manual
or automatic operation of the motor-driven device. MAGNETIC OVERLOAD RELAY
Table 2-9 describes the sequence of events when
operating the pilot device control circuit (table 2-10) A magnetic type of overload relay for a dc system
manually. is shown in figure 2-41. A pictorial view and a diagram

2-34
 Figure 2-41.—A magnetic overload relay.

identifying the various parts are shown in views A and two-wire control. They have a series coil (6) carrying
B, respectively. the load current and a shunt holding coil (7) mounted
above the series coil. These two coils are connected so
In an installation, the operating (series) coil (6) is
that their respective fields aid each other. Then, when
connected in series with the protected circuit. Normal
an overload occurs, the plunger moves up into the
current through the coil will have no effect on relay
shunt-connected field coil. It is held in the tripped
operation. If an overload occurs, increased current will
position until the shunt coil is de-energized, which can
flow through the coil and cause an increase in the
be accomplished when a reset button or some other form
magnetic flux around the coil. When the flux becomes
of contact (switch) device is pressed.
great enough, the iron plunger (5) will be lifted into the
center of the coil, opening the contacts (9 and 10). This Before placing the overload relay in service, raise
action opens the control circuit to the main contactor in the indicating plate (3) to allow the dashpot (1) to be
series with the motor terminals, which disconnects the unscrewed from the relay. Lift out the plunger (5) and
motor from the line. make certain all of the internal parts are clean. Place
about nine-sixteenths of an inch of dashpot oil
To keep the relay from operating when the motor is (furnished with the relay) in the dashpot. Replace the
drawing a heavy but normal starting current, an oil plunger and indicating plate, and then screw the dashpot
dashpot mechanism (1 and 2) is built in. This gives a on the relay to the desired setting.
time delay action that is inversely proportional to the
amount of overload. The relay is calibrated at the factory for the
individual application. The current values for which it
Overload relays may use either single or double is calibrated are stamped on the calibration plate (4).
coils. In addition, the single-coil overload relay maybe The marked values are minimum, maximum, and
obtained with or without a manual latching control (8). midpoint currents.
Relays with manual latching are used on three-wire
controls and reset automatically after an overload has You can set the operating points by first raising the
occurred. Double-coil overload relays are used for indicating plate (3), which allows the dashpot to be

2-35
turned Then, to lower the tripping current, raise the The operating (series) coil (6) is connected in series
dashpot by turning it. This action raises the plunger with the protected circuit. Therefore, the load current
further into the magnetic circuit of the relay so that a flows through the coil. If the circuit current rises above
lower current will trip the relay. normal because of overload conditions, it will cause an
increase in the magnetic lines of flux about the coil. The
You can increase the current at which the relay trips increased flux lifts the iron plunger (5) into the center
by turning the dashpot in a reverse direction. This action of the coil and opens the contactor/contacts (9). This,
reduces the magnetic pull on the plunger and requires in turn, causes the main contactor (not shown) to open,
more current to trip the relay. After the desired settings and disconnects the motor or other device from the line.
have been obtained, lower the indicating plate over the An oil dashpot mechanism (1 and 2) is used to prevent
hexagonal portion of the dashpot to again indicate the the operation of the relay on motor starting current
tripping current and lock the dashpot in position. surges.

Figure 2-42 shows two magnetic types of ac If the relay does not have manual latching, a
overload relays. View A is the nonlatching type, and three-wire control is provided to give automatic reset
view B is the latching type. In view C the various after an overload occurs. The manual-latch relay is
generally used with two-wire control. The latch (7)
components are identified
holds the contacts in the open position after an overload
has occurred and the circuits have been de-energized.
The operator must manually reset the overload relay at
the controller.

THERMAL OVERLOAD RELAY

The thermal type of overload relay (ac and dc) is

designed to open a circuit when excessive current causes
the heater coils to reach the temperature at which the
ratchet mechanism releases. The heater coils are rated
so that normal circuit current will not produce enough
heat to release the ratchet mechanism.

The essential operating parts of a de thermal

overload relay (fig. 2-43) are the two heater coils (4),
two solder tube assemblies (5), and control contacts (8).
Under normal conditions the splitter arm (7) (so called
because it splits the overload contacts) completes a
circuit with the contacts. The spring is then under
compression, and the operating arm (3) tends to rotate
the splitter arm out of the circuit. This action is
prevented by the ratchet assembly, which is held by the
solder film between the outer and inner part of the solder
tubes.

When current flows through the heater coils and

produces enough heat to melt the solder film, the inner
part of the solder tube assembly rotates and releases the
ratchet mechanism to open the control circuits. When
this happens, the circuit to the coil handling the power
contacts (not shown in fig. 2-43) opens and disconnects
the load. As soon as the load is disconnected, the heaters
cool, and the solder film hardens. When the hardening
is complete, the relay is ready to be reset with the reset
Figure 2-42.—Two ac overload relays. button.

2-36
 Figure 2-43.—An adjustable thermal overload relay and a reset magnet assembly.

The adjustable thermal relay may be adjusted to trip have reset magnet assemblies attached. You may have
at a value between 90 to 110 percent of the rated coil to replace the heater coils from the relay. If so, remove
current. To change the operating point, loosen the the four screws that hold the overload relay to the
binding screws that hold the relay heater coil (4) so that mounting plate. When removing the relay from the
the coil position may be changed. Moving the coil away
mounting plate, use care not to lose the phenolic pin and
from the relay will increase the amount of current
bearing block located between the thermal blocks on the
needed to trip the relay. Moving the coil closer to the
relay will decrease the current needed to trip the relay. underside of the relay.
This range of adjustment is available only within the Next, remove the four large countersunk screws that
range of 90 to 110 percent of coil rating. Each rating hold the mounting plate and the reset magnet assembly
has a different manufacture part number. The correct to the square posts. Remove the four screws in the
rating is installed when the controller is installed in the mounting plate, which support the reset magnet. Take
ship. Do not use another rating. Make sure both heater
care not to loosen the lever and spring (9 and 10).
coils in each overload relay are the same rating.
Remove the two screws (12) and pull the plunger guides.
The terminal plates and the underside of the slotted Remove the old coil (11) and install the new coil. Then
brackets of the heater coil assembly are serrated so that insert the plunger guides and replace the screws (12).
the coil is securely held in position when the binding Reassemble the magnet, spring, and lever to the
screws are tightened. Some thermal overload relays mounting plate. Mount the plate on the posts, and then

2-37
mount the overload relay on the mounting plate.
Replace the heater coils as the last operat.ion.

Overload relays are PROTECTIVE DEVICES.

After an overload relay has performed its safeguarding
function, you must reset it before running the system
again with overload protection.

REVERSE-POWER RELAY

On all ships with ac ship’s service power systems

where the generators are operated in parallel, each
generator control unit has a reverse-power relay. The
relay should trip the generator circuit breaker in
approximate] y 10 seconds with reverse power equal to
5 percent of the generator rating.

Reverse-power relays trip the generator circuit

breaker to prevent motoring the generator. This
protection is provided primarily for the prime mover or
Figure 2-44.—A coil and disk arrangement of an ac
system, rather than for the generator. Motoring results reverse-power relay.
from a deficiency in the prime mover input to the ac
generator. This deficiency can be caused by loss of or
low steam to the turbine, lack of fuel to the diesel engine
The main relay contacts (not shown in fig. 244) will
or gas turbine, or other factors that affect the operation
safely handle 30 amperes at 250 volts dc and will carry
of the prime mover. In the absence of reverse-power
the current long enough to trip a breaker.
protection, when the input to the generator falls below
that needed to maintain synchronous generator speed, The induction disk is rotated by an electromagnet in
real power is taken from the ship’s service power the rear of the assembly. Movement of the disk is
system. The generator acts as a motor driving the prime damped by a permanent magnet in front of the assembly.
mover. Reverse-power protection prevents damage to
The operating torque of the timer element is
the prime mover if a reverse-power condition should
obtained from the electromagnets (fig. 2-44). The
occur.
main-pole coil is energized by the line voltage. This coil
The reverse-power relay consists of two induction then acts as the primary of a transformer and induces a
disk-type elements. The upper element is the timer, and voltage in the secondary coil. Current then flows
the lower one is the direction element. Figure 2-44 through the upper pole coils. This produces a torque on
shows the coil and induction disk arrangement in the the disk because of the reaction between the fluxes of
induction-type relay timer element. The disk is 4 inches the upper and lower poles.
in diameter and is mounted on a vertical shaft. The shaft The timer element cannot be energized unless the
is mounted on bearings for minimum friction. power flow is in the direction that will cause tripping.
This interlocking action is accomplished by connection
An arm is clamped to an insulated shaft, which is
of the timer potential coil in series with the contacts of
geared to the disk shaft. The moving contact, a small
the directional element. Thus, the direction of power
silver hemisphere, is fastened on the end of the arm. The
flow controls the timer relay.
electrical connection to the contact is made through the
arm and a spiral spring. One end of the spring is The directional element is similar to the timing
fastened to the arm and the other end to a slotted element, except that different quantities are used to
spring-adjusted disk fastened to a molded block produce rotation of the disk. There is also a different
mounted on the element frame. The stationary contact contact assembly. The two upper poles of the
is attached to the free end of a leaf spring. The spring electromagnet are energized by a current that is
is fastened to the molded block, and a setscrew makes proportional to the line current, and the lower pole is
it possible to adjust the stationary contact position. energized by a polarizing voltage. The fluxes produced

2-38
by these two quantities cause rotation of the disk in a
direction depending upon the phase angle between the
current and voltage. If the line power reverses, the
current through the relay current coils will reverse with
respect to the polarizing voltage and provide a
directional torque.
The contact assembly and permanent magnet
construction are the same as that used for the timer
element. The timer element is rated at 115 volts, 60
hertz. The minimum timer element trip voltage is 65
volts, and its continuous rating is 127 volts.

The direction element has a power characteristic

such that, when the current and voltage are in phase,
maximum torque is developed. The potential coil is
rated at 70 volts, 60 hertz.

The current coil rating is 5 amperes, and the

minimum pickup current is 0.1 ampere through the coil.
This current is in phase with 65 volts (minimum) across
the potential coil. These are minimum trip values, and
the timing characteristic of the timing relay may be
erratic with low values.

For maximum protection and correct operation,

connect the relay so that maximum torque occurs for
unity power factor on the system. Because the
directional element has power characteristics, make the
connection by using line to neutral voltage for the
directional element potential coil (polarizing voltage)
and the corresponding line current in the series coils. If
a neutral is not available, you can obtain a dummy
neutral by connecting two reactors, as shown in figure
2-45. When connected in this manner, the directional
element voltage coil forms one leg of a wye connection,
and the reactors form the other two legs of the wye.
Connect the voltage-operated timer element across the
outside legs of the transformer secondaries. Figure 2-45.—Schematic wiring diagram of an ac
reverse-power relay.

REVERSE-CURRENT RELAY
The reverse-current relay connections are such that
when the reverse power reaches a definite percentage of
Two or more dc generators may be connected in the rated power output, it will trip the generator circuit
parallel to supply sufficient power to a circuit. Each dc breaker, disconnecting the generator from the line.
generator is driven by its own prime mover. If one prime Normally, the reverse-current settings for dc relays are
mover fails, its generator will slow down and draw about 5 percent of rated generator capacity for dc
power from the line. The generator will then operate as generators.
a motor, and instead of furnishing power to the line, it
will draw power from the line. This can result in The reverse-current relay (one for each generator)
damage to the prime mover and overloading of the is located on the generator switchboard and is an integral
generator. To guard against this possibility, use part of the circuit breaker. The mechanical construction
reverse-current relays. of a dc relay designed to limit reverse-current flow is

2-39
 Figure 2-46.—Mechanical construction of an dc reverse-current relay.

shown in figure 2-46. Note that the construction is spring tends to hold the tripping crank on the armature
similar to that of a bipolar motor with stationary pole shaft against a fixed stop. This pressure is maintained
pieces and a rotating armature. as long as current flows through the line in the right
direction.
Figure 2-47 shows the connections of a dc
reverse-current relay. The potential coil is wound on the
armature, and a current coil is wound on the stationary
pole pieces. When used as a protective device, the
current coil is in series with the load, and the potential
coil is connected across the line. If the line voltage
exceeds the value for which the potential coil is
designed, connect a dropping resistor at point X in the
circuit.

When the line is energized, current flowing through

the series coil produces a magnetic field across the air
gap. Voltage applied to the armature winding produces
a current in the armature coil, which interacts with the
magnetic field. A torque is developed that tends to rotate
the armature in a given direction. The construction of
the relay is such that the armature cannot turn through
360 degrees as in a motor. Instead, the torque produced
by the two fields plus the force from the calibrated Figure 2-47.—A dc reverse-current connection.

2-40
 If one generator fails, the voltage output of that
generator will drop. When the voltage drops below the
terminal voltage of the bus to which it is connected, the
generator terminal current (through the relay series coil)
will reverse. However, the polarity of the voltage
applied to the potential coil remains the same. When the
reversed current exceeds the calibration setting of the
relays, the armature rotates, and through a mechanical
linkage, trips the circuit breaker that opens the bus. This
action disconnects the generator from the line.

PHASE-FAILURE RELAY

Because the propulsion type of ac motors require

full voltage and current from all three phases supplied
by the generator, phase-failure protection is a
requirement for this type of shipboard propulsion.

This type of relay is used to detect short circuits on

alternating current propulsion systems for ships.
Ordinary instantaneous trip relays cannot be used
because, under certain conditions, when the motor is
plugged, the momentary current may be as great as the
short-circuit current.

The relay in use operates when there is a current

unbalance. It is connected in the control circuit so that
it will shutdown the system fault. However, operation
of the relay is not limited to short-circuit detection. The
relay may be used as a phase-failure relay. Figure 2-48
shows a phase-failure relay. View A is the arrangement Figure 2-48.—A phase-failure day.
of the parts in the complete assembly, and view B is a
closeup of the contact assembly. The entire unit is
enclosed in a cover to prevent dirt and dust from are not directly connected to the bus lines. Instead,
interfering with its operation. connection is made through the Rectox units, which are
connected to the line in series with a reactor.
The moving contact is the only moving element in
the complete relay. There are two stationary contacts
that make it possible to have the relay open or close a
circuit when it operates.

Two coils are built into the relay. Each coil has two
windings that are actuated by direct current from the two
Rectox units. Four reactors are used to get sensitivity
over a wide frequency range, Because variations in
reactance are introduced during manufacture, two
resistors are provided to balance the systems during the
initial adjustment.

Figure 2-49 is a schematic wiring diagram of a

phase-failure relay. The windings are identified by
numbers that refer to numbered leads in the three-phase
bus. Winding 1-3 is connected to lines 1 and 3; winding
1-2 is connected to lines 1 and 2; and the two windings Figure 2-19.—Schematic wiring of a phase-failure relay.
2-3 are connected to lines 2 and 3. However, the coils

2-41
 When all three-phase voltages are balanced, the flux Circuit breakers are available in manually or
produced by winding 1-2 is exactly equal and opposite electrically operated types. Some types may be
to that produced by winding 2-3. The flux produced by operated both ways, while others are restricted to one
winding 1-3 is exactly equal and opposite to that mode. Manually or electrically operated types may or
produced by the other 2-3 winding. Therefore, the may not provide protective functions. The differences
and uses of the various types of circuit breakers are
resultant flux is zero, and no magnetic pull is exerted on
described in the following sections.
the armature of the relay.

If a short circuit is placed across lines 1 and 2, no

flux is produced by winding 1-2. This means that the ACB
flux produced by one of the 2-3 windings is no longer
balanced, and there is a resultant flux, which exerts pull
The ACB type of circuit breaker maybe for either
on the relay armature. The armature moves until the
manual local closing or electrical remote closing. It has
moving contact hits stationary contact 2 (fig. 2-48, view an open metallic frame construction mounted on a
B). This action opens the circuit between the moving drawout mechanism and is normally applied where
contact and stationary contact 1. As soon as the short heavy load and high short-circuit currents are available.
circuit is removed from lines 1 and 2, the resultant flux Figure 2-50 shows the external view of a type ACB
is zero, which allows the spring to return the armature circuit breaker.
to its original position. Similarly, if shorts occur on lines
2 and 3 or lines 1 and 3, the resultant flux is no longer
zero, and the relay will operate.

Never open the dc circuit to the Rectox unit while

the voltage is being applied to the ac side. This
precaution is necessary because the voltage across the
Rectox is only a small portion of the total voltage drop
due to the reactor being in the circuit. If the dc side is
opened, full voltage is applied across the unit, which
may cause the unit to break down.

Very little maintenance is required for this relay. No

lubrication is needed. However, the relay must be kept
clean so that dirt and dust will not interfere with its
operation.

Because the relay rarely operates, check its

operation every month or two as recommended by
Naval Ships’ Technical Manual, chapter 320.

CIRCUIT BREAKERS

The purposes of circuit breakers are normal

switching operation, circuit protection, and circuit
isolation.

Air circuit breakers are used in switchboards, switch

gear groups, and distribution panels. The types installed
on naval ships are ACB, AQB, AQB-A, AQB-LF,
NQB-A, ALB, and NLB. They are called air circuit
breakers because the main current-carrying contacts Figure 2-50.—Type ACB circuit breaker.
interrupt in air.

2-42
 Type ACB circuit breakers are used to connect AQB
ship’s service and emergency generators to the power
distribution system, bus ties, shore connection circuits, Type AQB circuit breakers (fig. 2-51) are mounted
and some feeder circuits from the ship’s service in supporting and enclosing housings of insulating
switchboard. They are also used on submarines to material and have direct-acting automatic tripping
connect batteries, reactor coolant pump motors, and trim devices. The y are used to protect single-load circuits
and drain pump motors. and all feeder circuits coming from a load center
The reverse-power relay is mounted on the panel distribution panel.
close to the circuit breaker when it is used with ship’s
Where the requirements are low enough, the type
service and emergency generator breakers. Other
AQB may be used on generator switchboards. When it
automatic controls may be located at remote points to
becomes necessary to replace one of the older types of
give maximum protection to the circuit.
circuit breakers, replace it with the newer AQB-A101,
Circuit breaks designed for high currents have a AQB-A250, AQB-A400, AQB-A600, or AQB-A800 as
double-contact arrangement. The complete contact required.
assembly consists of the main bridging contacts and the
arcing contacts. All current-carrying contacts are
high-conductivity, arc-resisting silver or silver-alloy
inserts.

Each contact assembly has a means of holding the

arcing to a minimum and of extinguishing the arc as
soon as possible. The arc control section is called an arc
chute or arc runner. The contacts are so arranged that
when the circuit is closed, the arcing contacts close
first. Proper pressure is maintained by springs to ensure
the arc contacts close first. The main contacts then
close.

When the circuit opens, the main contacts open first.

The current is then flowing through the arc contacts,
which prevents burning of the main contacts. When the
arc contacts open, they pass under the front of the arc
runner. This causes a magnetic field to be set up, which
blows the arc up into the arc quencher and quickly
extinguishes the arc.

Type ACB circuit breakers are available in both

manually (hand-operated) and electrical] y operated
types. Electrically operated ACB breakers may be
operated from a remote location. The high interrupting
types are electrically operated because it is then
unnecessary for personnel to approach them to open or
close the circuit.

No circuit breaker, regardless of type, should be

worked on without opening the circuit. Remember,
certain terminals may have voltage applied to them even
Figure 2-51.—AQB-A250 circuit breaker complete, front view.
though the breaker is open. Aboard ship, power maybe
supplied to either end of the circuit breaker.

2-43
AQB-A250

The newer AQB type of circuit breakers, such as the

AQB-A250, have several advantages over the older
types. The outside dimensions of these new breakers
are the same for both the two-pole and three-pole circuit
breakers. They are designed for front and rear
connections. They may be mounted so as to be
removable from the front without removing the circuit
breaker cover. The voltage rating of the AQB-A250 are
500 volts ac, 60/400 hertz or 250 volts dc.

The 250 part of the circuit breaker designation

indicates the frame size of the circuit breaker. In a
250-ampere frame size circuit breaker, the
current-carrying parts of the breaker have a continuous
rating of 250 amperes. Trip units (fig. 2-52) for this
breaker are available with current ratings of 125, 150,
175, 225, and 250 amperes.

The trip units houses the electrical tripping

mechanisms, the thermal elements for tripping the
circuit breaker on overload conditions, and the
instantaneous trip for tripping on short-circuit
conditions.

In addition, 100-, 160-, and 250-ampere rating trip

units with a special calibration are available for use with
generator circuit breakers. Regardless of the trip unit
used, the breaker is still a 250-ampere frame size. The
automatic trip devices of the AQB-A250 circuit breaker
are “trip free” of the operating handle; in other words,
the circuit breaker cannot be held closed by the
operating handle if an overload exists. When the circuit
breaker has tripped due to overload or short circuit, the
handle rests in a center position. To reclose the circuit Figure 2-52.—AQB-A250 circuit breaker complete front view,
breaker after automatic tripping, move the handle to the with cover and arc suppressor removed.

extreme OFF position. This resets the latch in the trip

unit. Then move the handle to the ON position. setting of the AQB-A250 trip units maybe adjusted by
the instantaneous trip adjusting wheels (12) shown in
The AQB-A250 circuit breaker may have auxiliary figure 2-53, view A. These trip adjusting wheels are
switches, shunt trip (for remote tripping), or marked for five positions, LO-2-3-4-HI. The trip unit
undervoltage release attachments. A shunt trip cannot label (not shown) will list the instantaneous trip value
be provided in the same breaker with an undervoltage obtainable for each marked position. Identical settings
release. Figure 2-53 shows a trip unit with a shunt trip must be made on each pole of the circuit breaker.
(view A) and a trip unit with an undervoltage trip (view NEVER remove a circuit breaker cover to perform
B). The coil for a shunt trip has a dual rating for ac and adjustments while the circuit breaker is in the closed
dc voltages. The undervoltage trip coils are wound for (ON) position.
a specific voltage, such as 450 ac or 250 dc and have Terminal mounting block assemblies
rated pickup and dropout values. The instantaneous trip used in conjunction with the circuit breaker

2-44
Figure 2-53.—AQB-A250 trip unit; (a) with shunt trip and auxiliary unit; (b) with undervoltage release and auxiliary switch.

2-45
 Figure 2-54.—AQB-A250 circuit breaker, rear view, with terminal mounting blocks.
(fig. 2-54) for drawout mounting consist of terminal
studs in terminal mounting blocks of insulating material.
The terminals of the circuit breaker have slip-type
connectors, which engage the terminal studs as shown
in figure 2-54. Two mounting blocks are usually
required for each circuit breaker. This method of
connecting a circuit breaker to a bus or circuit is known
as a back-connected circuit breaker. Circuit breakers
that have solderless connectors attached to their
terminals are commonly called front-connected circuit
breakers. The interrupting rating of the AQB-A250
circuit breaker is 20,000 amperes at 500 volts ac, 60
hertz; 10,000 amperes at 500 volts ac, 400 hertz; or
15,000 amperes at 250 volts dc.

AQB-LF250

The AQB-LF250 circuit breaker (fig. 2-55)

combines the standard AQB circuit breaker and a
current-limiting fuse unit, which interrupts the circuit
when the current is in excess of the interrupting rating
of the breaker. Constructed as one compact unit, the
AQB-LF circuit breaker incorporates the
current-limiting fuses (fig. 2-56) as integral parts of the
circuit breaker. The common trip features and trip units
in this type of circuit breaker are identical to those in the
AQB-A250 circuit breakers.

The current-limiting fuse unit is designed so that it

trips the breaker and opens all poles if any
current-limiting fuse (fig. 2-57) is blown. After a fuse Figure 2-55.—AQB-LF250 complete circuit breaker, front view.

2-46
Figure 2-56.—Complete circuit breaker, front view, with fuse unit removed.

Figure 2-57.—Current-limiting fuse unit assembly.

2-47
has blown, the circuit breaker cannot be reclosed until
the blown fuse is replaced. Any attempt to remove the
fuse unit when the circuit breaker is in the closed
position will automatically trip the breaker.
The AQB-LF250 circuit breaker is interchangeable
with the AQB-A250 circuit breaker except a larger
cutout is required in the switchboard front panel to
accommodate the fuse unit of the AQB-LF250.

The AQB-LF250 circuit breaker is a 250-ampere

frame size. However, the circuit breaker has an
interrupting rate of 100,000 amperes at 500 volts ac, 60
hertz. The AQB-A250 circuit breakers has an
interrupting rating of 20,000 amperes at 500 volts ac, 60
hertz.

While the AQB-A250 circuit breaker could be

either front or back connected, the AQB-LF250 is
designed only for back (drawout type) connection. It
uses the same type of slip connector terminal studs as
shown in figure 2-54.

NQB-A250

The NQB-A250 circuit breaker (fig. 2-58) is similar

to the AQB-A250 circuit breaker except the NQB-A250
has no automatic tripping devices. This type of circuit
Figure 2-58.—NQB-A250 circuit breaker, front view with
breaker is used for circuit isolation and manual transfer , cover removed.
applications. The NQB-A250 is still a 250-ampere
frame size. The current-carring parts of the breaker are
NLB
capable of carrying 250 amperes. Technically, this
circuit breaker is simply a large on-and-off switch.
The NLB circuit breakers are identical to the ALB
Some types of AQB and NQB breakers are provided
circuit breakers except that they have no automatic
with electrical operators mounted on the front of the
tripping device. They are used only as on-off switches.
breaker. These are geared motor devices for remote
operation of the breaker handle.
Maintenance

ALB When you work on circuit breakers, there are

several precautions you should take. The most
The ALB circuit breakers are designated important precaution you should remember to take is to
low-voltage, automatic circuit breakers. The de-energize all control circuits to which the circuit
continuous duty rating ranges from 5 through 200 breaker is connected. The procedures differ somewhat
amperes at 120 volts ac or dc. The breaker is provided with the type of mounting being used.
with a molded enclosure, drawout type of connectors,
When working on drawout circuit breakers, make
and nonremovable and nonadjustable thermal trip
sure that they are switched to the open position. Then
elements.
the circuit breaker may be removed.
This circuit breaker is a quick-make, quick-break
When working on fixed-mounted circuit breakers,
type. If the operating handle is in the tripped (midway
open the disconnecting switches ahead of the breakers.
between ON and OFF) position, indicating a short
circuit or overload, the operating handle must be moved If disconnecting switches are not provided for
to the extreme off position. This automatically resets isolation, you need to de-energize the supply bus to the
the overload unit and the breaker can again be closed. circuit breaker.

2-48
 Circuit breakers have different time delay cases, dress and clean the contact surface using fine (No.
characteristics. Some have a short time, long time, or 00) sandpaper (the use of fine sandpaper prevents
instantaneous trip. scratching the surface of the contact.) Never use emery
cloth or emery paper. Because this copper-oxide film
The adjustments for selective tripping of most is a partial insulator, follow the sanding procedures by
circuit breakers are made and sealed at the factory. wiping with a clean cloth moistened with inhibited
Normally, you would not make changes to the circuit methyl chloroform solvent.
breaker trip settings because changes may completely
disrupt the circuit breaker protection functions. If there NOTE: Ventilate the space when using inhibited
is improper tripping action in the compact assemblies, methyl chloroform to remove all deadly and toxic
you should correct the problem by replacing the entire fumes of the solvent.
breaker. ARCING CONTACTS.— The function of arcing
After circuit breaker covers have been removed, contacts is not necessarily impaired by surface
you should check the interior components, such as roughness. You should use a fine file to remove
contacts, overcurrent tripping devices, connections, and excessively rough spots. Replace arcing contacts when
moving mechanical parts. they have been burned severely and cannot be properly
adjusted. Make a contact impression and check the
Contacts are small metal parts especially selected to spring pressure following the manufacturer’s
resist deterioration and wear from the inherent arcing. instructions. If information on the correct contact
In a circuit breaker, arcing occurs while its contacts are pressure is not available, check the contact pressure with
opening and carrying current at the same time. When that of similar contacts that are functioning properly.
firmly closed, the contacts must not arc. When the force is less than the designed value, you
should either replace the contacts if they are worn down
The material used to manufacture contacts has been
or replace the contact springs. Remember, always
diligently researched. The result of this research is
replace contacts in sets and replace the contact screws
contacts made from various metals and/or alloys that
at the same time. Do not clean contacts when the
range from pure carbon or copper to pure silver, each
used alone and as an alloy with other substances. equipment is energized.
CHECKING CIRCUIT BREAKERS.— Some of
SILVER CONTACT MAINTENANCE.—
the checks you should make on circuit breakers include
Modem circuit breakers have contacts coated with
cleaning the surfaces of the circuit breaker neck,
silver, silver mixed with cadmium oxide, or silver and
checking arcing contacts, oil piston tripping devices,
tungsten. The two silver alloys are extremely hard and
and sealing surfaces of circuit-breaker contactor and
resist being filed. Contacts made of silver or silver
relay magnets.
alloys conduct current when discolored (blackened
during arcing) with silver oxide. Therefore, the You should clean all surfaces of the circuit breaker
blackened condition doesn’t require filing, polishing, or mechanism with a dry cloth or air hose. When cleaning
removal. However, if the silver contact is severely the surfaces, pay particular attention to the insulation
pitted or burned, it may require some filing to remove surfaces. Before directing the air on the breaker, make
raised places on surfaces that prevent intimate and sure the water is blown out of the hose, the air is dry, and
overall closure of the contact surfaces. In this case, the the pressure is not over 30 psi. Check the pins, bearings,
contact should be filed by using a fine file or with fine latching, and all contact and mechanism springs for
sandpaper, No. 00. If necessary, you may use a clean excessive wear or corrosion and evidence of
cloth moistened with inhibited methyl chloroform. overheating. Replace parts if necessary.
NOTE: Ventilate the space when using inhibited Be certain that the arcing contacts make-before and
methyl chloroform to remove all deadly and toxic break-after the main contacts. If poor alignment,
fumes of the solvent. sluggishness, or other abnormal conditions are noted,
adjust the contacts following the manufacturer’s
COPPER CONTACT MAINTENANCE.—
instructions.
When cleaning and dressing copper contacts, maintain
the original shape of each contact surface and remove Oil-piston type of overcurrent tripping devices
as little copper metal as possible. Inspect the entire (grade B timers) are sealed mechanisms and normally
contact surface and wipe the copper contact surfaces to do not require any attention. When oil-film (dashpot)
remove of the black copper-oxide film. In extreme overcurrent tripping devices are used, and the dashpot

2-49
oil requires replacing, you should remove the oil, clean Inspections
the interior with kerosene, and refill the dashpot to the
proper level with new oil. Ensure that the dashpot is free Circuit breakers require careful inspection and
of dirt, which may hinder the time-delay effect, and that cleaning at least once a year. If they are subjected to
unusually severe service conditions, you should inspect
the tripping device is clean, operates freely, and has
them more frequently. Also, if a circuit breaker has
enough travel to trip the breaker. Do not change the
opened due to a heavy load, it should be inspected.
air-gap setting of the moving armature because this
would alter the calibration of the tripping device. Calibration
Lubricate the bearing points and bearing surfaces
(including latches) with a drop or two of light machine Perform calibration of circuit breakers following
oil. Wipe off any excess oil. the Naval Ships’ Technical Manual, chapter 300,
recommendations.
The sealing surfaces of circuit-breaker contactor
and relay magnets should be kept clean and free from
Metal Locking Devices
rust. Rust on the sealing surfaces decreases the contact
force and may result in overheating of the contact tips. Metal locking devices are available that can be
Loud humming or chattering will frequently warn of this attached to the handles of AQB circuit breakers to
condition. Alight machine oil wiped sparingly on the prevent accidental operation. All breaker handles are
sealing surfaces of the contactor magnet will aid in provided with a 3/32-inch hole that permits the locking
preventing rust. device to be fastened with a standard cotter pin. Naval
Ships’ Technical Manual, chapter 300, provides a list of
If wiping arc chutes or boxes with a cloth is not
the stock numbers for three different sizes of breaker
sufficient, clean them by scraping with a file or cleaning handle locking devices.
pad. Replace or provide new linings when arc chutes or
box linings are broken or burned too deeply. Be certain SELECTIVE TRIPPING
that arc chutes are securely fastened and that there is
sufficient clearance to ensure that no interference occurs The purpose of selective tripping is to isolate the
when the switch or contact is opened or closed faulty section of the system and, at the same time, to
maintain power on as much of the system as possible.
If the shunt and flexible connectors are worn broken Selective tripping of circuit breakers is obtained by
or frayed, they should be replaced. The shunt and coordination of the time-current characteristic of the
flexible connectors are flexed by the motion of moving protective devices so that the breaker closest to the fault
parts. will open first. The breaker farthest from the fault and
closest to the generator will open last.
If working surfaces of circuit breakers, contractors,
motor controllers, relays, bearings, and other control Figure 2-59 shows a portion of a distribution system
equipment show signs of rust, you should disassemble with circuit breakers employing selective tripping. The
the device and clean the rusted surfaces. Use a light so-called instantaneous tripping time is the minimum
application of oil over the cleaned parts to prevent time required for a breaker to open and clear a circuit
when the operation of the breaker is not intentional y
further rusting. The oil should always be used sparingly
delayed. Each circuit breaker will trip in less than 0.1
when wiping over rusted parts that have been cleaned to
second (almost instantaneously) when the current
prevent further rusting. Remember, oil has a tendency
exceeds the instantaneous trip current setting of the
to accumulate dust and grit, which may cause breaker. In a shipboard selective tripping power system,
unsatisfactory operation. the individual circuit breakers (generator, bus tie, shore
Before returning a circuit breaker to service, inspect power, or feeder breakers) differ from each other
depending on the following factors:
all mechanical and electrical connections, including
mounting bolts and screws, draw-out disconnect • The available load current
devices, and control wiring. lighten where necessay.
• The available short-circuit current
Operate the circuit breaker manually to make sure that
all moving parts function freely. Check insulation • The tripping time band and trip current settings
resistance. selected

2-50
 Figure 2-59.—Selected tripping of circuit breakers.

Selective tripping of breakers is normally obtained Refer to figure 2-59. Assume that a fault or defect
by a short time-delay feature. This feature is a develops in the cable insulation at point A. An
mechanical time delay and can be varied with overcurrent flows through the AQB load circuit breaker
limitations. The generator circuit breaker, which is and the ACB feeder circuit breaker. The AQB load
closest to the power source, has the maximum breaker will open the circuit and interrupt the current in
continuous current-carrying rating, the highest available an interval of time that is less than the time required to
short-circuit current rating, and the maximum short time open the ACB feeder circuit breaker. Thus, the ACB
delay trip. This allows the generator breaker to be the feeder breaker will remain closed when the AQB
last breaker to trip. However, it will trip on the generator breaker clears the circuit. However, if the fault current
short-circuit current at some definite interval of time should exceed the interrupting capacity of the AQB load
within the tolerance of the breaker. Bus tie circuit breaker (for example, an excess of 10,000 amperes), this
breakers are usually set to trip after a prescribed time breaker would be unable to interrupt the fault current
delay that is less than the generator circuit breaker set without damage to the breaker. To prevent damage to
time delay. the AQB load breaker, the ACB feeder breaker (on
switchboard 1S) serves as a backup breaker for the
The construction of circuit breakers for selective AQB load breaker and will open almost instantaneously.
tripping for currents less than the instantaneous trip
current setting causes an intentional delay in the A fault at point B with overcurrent would trip the
operation of the breaker. The time delay is greater for ACB feeder breaker in time but not the ACB generator
small currents than for large currents and is therefore or bus tie breakers. They require longer time intervals
known as an inverse time delay. The current that would in which to trip.
trip the AQB load circuit breaker instantaneous] y and
clear the circuit will not trip the ACB feeder circuit A fault at point C with overcurrent would trip both
breaker unless the current flows for a greater length of ACB bus tie breakers.
time. The same sequence of operation occurs for the A fault at D with overcurrent on switchboard 1S
other groups of circuit breakers adjusted for selective would trip the associated ACB generator breaker and
tripping in the system. The difference between the one or both of the ACB bus tie breakers.
tripping times of the breakers is sufficient to permit each
breaker to trip and clear the circuit before the next In each case, the faulty section of the system is
breaker starts to operate. isolated, but power is maintained on as much of the

2-51
system as possible with respect to the location of the TYPES OF RECEPTACLES
fault.
On the older ships with single 125-volt, 10-ampere,
The attainment of selective tripping requires careful
single-phase ac (or two-wire de), stub-type watertight
coordination of time-current characteristics for the
receptacles are used for all applications except for
different groups of circuit breakers. For example, if the
electric shavers and some electronic applications. For
system shown in figure 2-59 is operating split plant (bus
electric shavers and some electronic applications,
ties open) and if the time-current characteristics of the
double 125-volt, 15-ampere, single-phase ac (or
ACB feeder breaker and the ACB generator breaker
two-wire dc) bladed-type receptacles are used
were interchanged, a fault at B with overcurrent would
trip generator 1SG off the line but would leave the feeder On new ships, general-purpose grounded
connected to the switchboard. This action would receptacles are provided as follows:
disconnect power to all equipment supplied by
1. Double 125-volt, 15-ampere, single-phase ac (or
switchboard 1S and also would not isolate the faulty
two-wire dc) bladed-type receptacles are used
section. Therefore, no unauthorized changes should be
for all below-deck applications.
made to circuit breaker trip settings because these
changes may completely disrupt the scheme of 2. Single 125-volt, 15-ampere, single-phase ac (or
protection based on selective tripping. two-wire de) watertight bladed-type receptacles
are installed on radar platforms and open bridges
System protection by selective tripping of circuit
for use of electronic test equipment.
breakers cannot be provided to all types of naval ships
or for all circuits. For example, dc distribution systems 3. Single 125-volt, 10-ampere, single-phase ac (or
in older ships and all lighting circuits use fuses to a great two-wire dc) stub-type submersible receptacles
extent. Time delay can be incorporated only to the are used topside and for applications where a
extent that is permitted by the characteristics of the watertight receptacle is require&except on radar
fuses. The use of progressively large fuse sizes from the platforms and open bridges.
load to the generator provide some degree of selectivity
for overload or limited fault protection. RECEPTACLE LOCATION

Receptacles must be spaced to permit the use of

GROUNDED RECEPTACLES portable tools at anyplace on the ship without requiring
more than 50 feet of flexible cable between a tool and
Grounded receptacles are installed aboard naval
receptacle. Receptacles installed for specific
vessels to ensure that grounded plugs, portable cables,
applications, such as radiant heaters, are included in the
and portable electrical tools are grounded to the ship’s
receptacle spacing to meet the 50-foot limit. They may
structure when they are in use. The ground wire
be considered as available for portable tools.
prevents the occurrence of dangerous potentials
between the tool or equipment housing and the ship’s If additional receptacles are required to meet the
structure. This protects the user from fatal shock. 50-foot limit, make sure that added receptacles don’t
result in overloading the circuits. In some ships the
The grounded receptacles most widely used aboard
receptacles are on an isolated circuit as an additional
naval vessels have metal enclosures internally
means of preventing fatal shocks.
connected to the ground terminal of the receptacle.
Grounding the enclosures will ground the grounded
RECEPTACLE TESTING
terminal. Grounded receptacles with plastic enclosures
are also used aboard some vessels. In some types, the
The routine ground continuity test of each installed
grounded terminal is connected to ground through a
receptacle is required by PMS. Before a receptacle is
conductor. In later types, the grounding ferrules are
ground tested, it must be de-energized, safety tagged,
molded within the mounting. The ground wire is also
and checked for voltage. This safety precaution will
molded within the bottom of the box and connects the
protect you and the test equipment.
grounding terminal to the metal insert. The
cross-sectional area of the conductor used to connect the In one method of testing, you connect one test lead
grounded terminal to ground must be at least the same of an ohmmeter or multimeter to the ground lead of a
size or greater than that of the conductors that supply a dummy plug of the receptacles to be tested. The power
receptacle. prongs of this plug are to be left unconnected. Insert the

2-52
plug into the receptacle to be tested. Touch the probe of However, if the equipment was originally provided with
the other test lead of the meter to the ship’s structure. a grounding cord and plug, this type cord and plug must
The reading should be less than 1 ohm. be retained throughout the life of the device. Equipment
stamped DOUBLE INSULATION or DOUBLE
If a receptacle tests unsatisfactory, it should be
INSULATED must have only two prong plugs and
immediately repaired or tagged with a red danger tag to
cords. At the discretion of the inspection authority,
indicate that it must not be used Keep a record of the
three-prong plugs and cords may be installed on other
locations of all grounded receptacles and the dates they
equipment if the ground conductor can be conveniently
were tested.
connected to the exposed metal parts, and the
modification does not compromise the equipment
ELECTRICAL EQUIPMENT operation or the enclosure integrity.
ABOARD SHIP

The Navy has adopted a policy to use commercially CAUTION

available tools and equipment, when feasible. No
specific guidance can be provided to cover all portable A wide range of miscellaneous portable
tools and equipment. Much of the burden of accepting electric equipment may be received aboard
and rejecting portable electrical and electronic ship without being provided with a cord that
equipment falls on the electrical or electronic officer or has a grounding conductor and a grounded
other designated personnel to perform the initial plug that is not plastic encased. This
inspection. equipment includes galley equipment (fruit
juice extractors, food-mixing machines,
APPROVAL FOR USE coffee pots, toasters); office equipment
(adding machines, addressograph
Nonconducting cased portable tools and equipment machines); shop equipment (key duplicating
do not require grounding cords or plugs, provided the machines, valve grinders, mica undercutter,
equipment meets both of the following requirements: hot plates); medical equipment (infrared
lamps, ultraviolet lamps, sterilizers); barber
1. Passes an initial inspection for rugged, safe
shop equipment (hair clippers); and laundry
construction, and
equipment(flatirons)
2. Has a minimum of 1 megohm dc resistance from
any phase to any exposed metal part (such as When electrically operated equipment is issued to
chuck housing, mounting screws, ear plug jacks, the ship without a grounding conductor or grounded
or antennas) or metal chassis. plug, it must have a three-conductor flexible cable and
The following equipment is acceptable for use aboard grounded plug installed before it is used.
ship: (Nonconducting plastic-cased portable electric tools are
excluded.)
• If the portable tool or equipment has the words
DOUBLE INSULATION or DOUBLE INSULATED The three-conductor flexible cable should be type
stamped on its enclosure, it is assumed to be of rugged, SO or ST color-ceded black, white, and green, as listed
safe construction. This stamping designation is an in the Navy Stock List of General Stores, Group 61. For
underwriters requirement; however, this requirement is general use, the plugs should be bladed and have
only applicable to selected type of equipment. Portable U-shaped grounding prongs. These plugs are available
equipment, which hasn’t been stamped DOUBLE for use with small and large diameter cords. Stub-type
INSULATION or DOUBLE INSULATED, will be plugs that can be made watertight (formerly designed as
acceptable if they meet the two requirements listed type SNR) are now furnished with plastic shells.
above.
PERMANENTLY MOUNTED EQUIPMENT
• All equipment, when tested with a Megger, must
have at least 1 megohm resistance between either sides
Electrical equipment that is permanently mounted
of the line and any exposed metal of the equipment.
to the hull of the ship does not require an additional
When equipment meets the above criteria, it is ground wire. However, equipment installed with shock
acceptable for use with a two prong plug and cord. mounts does require an external ground cable.

2-53
Additionally, this equipment must be “hard wired” to the bending or twisting the cable causes a change in
power source vice having a cord with a plug attached resistance, the strands in the grounding conductor are
broken and the cable must be replaced.
TESTING ELECTRICAL EQUIPMENT
The SNR plug must be checked on equipment and
extension cord. Using a megohmmeter, measure the
Before using portable electrical equipment for the
insulation resistance between the brass shell and each
first time, test the plug connections of the equipment for
contact on the plug. Push on, pull on, twist, and bend
correct wiring. Do the testing in a workshop equipped
the cable while you take measurements. If the
with a nonconducting surface workbench and approved
resistance measures less than 1 megohm, check for
rubber deck covering. Conduct the test according to
twisted bare wires in the plug. Rewire a defective plug
current PMS procedures.
and replace the brass shell of the plug with a
nonconducting plastic (nylon) shell. If the plug has to
Portable and Mobile Equipment
be replaced due to wear and tear, renew the plug tip and
replace the brass plug shell with a nylon shell. Reuse
All portable and mobile electrical equipment must
brass shells only if the nylon plug shells are not in stock.
be periodically tested and visually inspected. A list of
In this case, rewire and retest the brass shell plug for
such equipment must be established noting the locations
and serial numbers. The following items should be temporary use until the nylon shell becomes available.
included: There are two sizes of nylon plug shells. One size is
used for 0.425-inch-diameter cables or smaller, the other
1. Portable, hand-held electric tools that are size for 0.560-inch-diameter cables.
permanently loaned out to other shipboard
departments or divisions
WORKMANSHIP
2. Electric equipment that is frequently touched,
such as hot plates, coffee makers, toasters, Cord conductors must be fastened securely and
portable vent sets, movie projectors, and office properly to wiring terminals. Aboard ship in portable
equipment. equipment, extension cords, portable receptacles, and
All faulty equipment must be removed from service plugs, the conductor ends are crimped or soldered into
until they are repaired and properly safety checked. standard eyelets (or hooks where the terminal screws are
not removable). If eyelets or hooks are not available,
Bladed Plugs (Round or U-shaped Contact) twist the strands of each conductor together tightly and
form into an eyelet or a hook. Then, coat the formed
Before testing a bladed plug, check to see that the eyelet or hook with solder to hold the strands together
insulation and contacts are in good condition and that unless the manufacturer’s instructions forbid tinning of
the conductors are secured properly under the terminal the leads. There must be no loose strands to come in
screws. Using a volt-ohmmeter, measure the resistance contact with metal parts. This would place line potential
from the ground contact to the equipment housing. The on the metal shell of the plug when it is partially inserted
measurement must be less than 1 ohm. Move or work in an energized receptacle. A fatal hand-to-hand
the cable around by bending or twisting it. A change of electrical shock can result if the receptacle is on the end
resistance indicates broken strands in the grounding of an energized extension cord and has its metal case
conductor. This means the cable must be replaced raised to line potential (of opposite polarity to that on
the shell of the plug) by loose conducting strands at the
Navy SNR Plugs cord connection to the receptacle.

Examine all cords to make sure they are

You must examine the type SNR plugs to make sure
connected properly to their terminals. Remove
the insulation and contacts are in good condition and that
damaged plugs and cords that are improperly connected,
the conductors are secured properly under the terminal
torn, or chafed from service. (NOTE: Don’t cut open
screws. Then check to see that the plug is clean and that
molded rubber plugs and receptacles for examination.)
the contacts (in particular the ground contact) are free
of hangover fringes of molded insulation that could If the grounding conductor connected to the metallic
prevent making good contact. Measure the resistance equipment casing is inadvertently connected to a line
from the ground contact to the equipment housing. contact of the plug, a dangerous potential will be placed
Again, the measurement must be less than 1 ohm. If on the equipment casing. The person handling the

2-54
portable metal-cased equipment will receive a fatal sized of cable; nonflexing and flexing service; cable
shock when it is plugged into a power receptacle, construction, selection, and installation; conductor
because the line voltage will be on the exposed parts of identification; and cable markings and maintenance.
the equipment. Make sure that all connections are
Other information contained in this chapter includes
right before using the tool, equipment, or receptacle.
a discussion of casualty power cables, shore-power
Extension cords are authorized for use with portable cables, the phase-sequence indicator, stuffing tubes,
tools and equipment. They consist of 25 feet of
deck risers, wireways, and cable supports. Additionally,
three-conductor flexible cable (which includes the
we provided information about control devices, relays,
grounding wire) with a grounded plug attached to one
circuit breakers, grounded receptacles, and plugs and
end and a grounded type of portable receptacle suitable
for receiving the grounded type of tool or equipment cords.
plug on the other end. For technical information not included in this
TRAMAN, please refer to the Cable Comparison
SUMMARY Guide, NAVSEA 0981-052-8090; Cable Comparison
In this chapter, you learned about the electrical Handbook, MIL-HDBK-299 (SH); the Electronics
cables presently installed aboard ship and the newer Installation and Maintenance Book, N A V S E A
low-smoke cables now being used. By reading this 0967-000-0110; and Naval Ships’ Technical Manual,
chapter, you were introduced to the various types and Chapters 300, 320, and 475.

2-55
 CHAPTER 3

ELECTRICAL DISTRIBUTION
SYSTEMS

Almost every function undertaken aboard a naval distribution system to be distributed to the various
ship depends upon electric power for its electrical loads throughout the ship.
accomplishment. From the launching of missiles against The ac power distribution system aboard ship is
an aggressive force to baking bread for lunch, electric made up of the following parts:
power is vital to a ship’s ability to accomplish its
mission. • AC power plant

• Switchboards that distribute the power

LEARNING OBJECTIVES • The equipment that consumes the power
Upon completion of this chapter, you should be able The ac power distribution system consists of the
to do the following: following three parts:
1. Identify the various electrical distribution 1. The service power distribution system
systems installed on board Navy ships.
2. The emergency power distribution system
2. Identify the characteristics and construction
3. The casualty power distribution system
features of and recognize the operation of ac
generators.
ELECTRICAL DISTRIBUTION
3. I d e n t i f y s o m e w o r k i n g p r i n c i p l e s , SYSTEM
characteristics, and design features of
transformers. The electrical distribution system is the link
4. Recognize several factors that determine the between the ship’s source of electrical power and the
output voltage and frequency of ac generators. ship’s electrical loads. Power is normally supplied from
the ship’s own generators but can be supplied from an
5. Identify various operating fundamentals of external source through the shore power cables. In
ship’s service distribution systems, including naval ships, most ac power distribution systems are
switchboards, bus transfer equipment, and 450-volt, three-phase, 60-Hz, three-wire systems.
shore power.
Bus ties interconnect the ship’s service generator
6. Recognize various principles and procedures in and distribution switchboards. Therefore, any
rigging or unrigging casualty power. switchboard can be connected to feed power from the
7. Recognize distinct maintenance and test generators to one or more of the other switchboards
procedures used in keeping an electric plant on allowing the generators to operate in parallel. In large
the line. installations (fig. 3-1), power from the generators goes
through distribution switchboards or switchgear groups
to the load centers, through distribution panels, and on
AC POWER DISTRIBUTION to the loads. Distribution may also be direct from the
SYSTEM load centers to some loads.

The ship’s service electric plant is that equipment On some large ships, such as aircraft carriers, a
that takes the mechanical power of a prime mover and system of zone control of the ship’s service and
converts it into electrical energy. The prime mover may emergency power distribution system is provided. The
be steam, gas turbine, diesel, or motor driven. The system sets up several vertical zones that contain one or
mechanical energy of the prime mover is converted into more load center switchboards supplied through bus
electrical energy in the ship’s service generators. These feeders from the ship’s service switchgear group. A load
generator sets supply power to the ships ac power center switchboard supplies power to the electrical loads

3-1
 Figure 3-1.—Power distribution in a large combatant ship.

within the electrical zone in which it is located. Thus,

zone control is provided for all power within the CREW LIVING SPACE, FRAMES XX -XX
electrical zone. An emergency switchboard may supply
more than one zone. FIRST PLATFORM
In small installations (fig. 3-2), the distribution LIGHTING PANEL 4-108-2
panels may or may not be fed directly from the generator
and distribution switchboards. The distribution panels 2S-4L-(4-103-2)
and load centers, if installed, are located centrally with
respect to the loads that they feed. This arrangement
simplifies the installation and requires less weight, If a panel contains two or more sets of buses and each
space, and equipment than if each load were connected set is supplied by a separate feeder, the number of each
to a switchboard. feeder is indicated on the identification plate.
Distribution panels have circuit information plates
next to the handle of each circuit breaker or switch.
Circuit Markings These plates contain the following information in the
order listed:

All distribution panels and bus transfer equipment 1. The circuit number
have cabinet information plates (shown below). These 2. The name of the apparatus or circuit controlled
plates contain the following information in the order
listed: 3. The location of the apparatus or space served
4. The circuit breaker element or fuse rating
1. The name of the space, apparatus, or circuits
served Vital circuits are shown by red markers attached to
circuit information plates. In addition to the red marker,
2. The service (power, lighting, electronics) and
information plates for circuit breakers supplying circle
basic location number
W- and circle Z-class ventilation systems contain, the
3. The supply feeder number class designation of the ventilation system supplied.

3-2
 Figure 3-2.—Power distribution in a gas turbine powered DDG.

Information plates without markings are provided for pumps, driven by three-phase motors. The phase
spare circuit breakers mounted in distribution panels. sequence of the power supply throughout a ship is
Panel switches controlling circuits that are de-energized always ABC (regardless of whether power is supplied
during darkened ship operations are marked from any of the switchboards or from the shore power
DARKENED SHIP. The ON and OFF position of these
switches are marked LIGHT SHIP and DARKENED
SHIP, respectively.
Circuit information plates are provided inside fuse
boxes (next to each set of fuses). They show the circuit
controlled, the phases or polarity, and the ampere rating
of the fuse.

Phase Sequence

The phase sequence. in naval ships is ABC (fig. 3-3);

that is, the maximum positive voltages on the three
phases are reached in the order A, B, and C. Phase
sequence determines the direction of rotation of
three-phase motors. Therefore, a reversal of the phase
sequence could cause damage to loads, especially Figure 3-3.—Sine curve for three-phase circuit.

3-3
connection) to ensure that three-phase, ac motors will three-phase circuits. For explanation purposes, the
always run in the correct direction. three-phase unit will be discussed. As you read this
Phase identification is shown by the letters A, B, and section, refer to figures 3-4 and 3-5.
C in a three-phase system. Switchboard and distribution The A-2 ABT is designed to shift automatically
panel bus bars and terminals on the back of switchboards from normal to the alternate or emergency source of
are marked to identify the phase with the appropriate
power when the source voltage drops to the dropout
letters, A, B, or C. The standard arrangement of phases
range (81 -69 volts) across any two of the three phases.
in power and lighting switchboards, distribution panels,
feeder distribution boxes, feeder junction boxes, and Upon restoration of normal power (98-109 volts), the
feeder connection boxes is in the order A, B, and C from unit will transfer back to the normal power supply. An
top to bottom, front to back, or right to left when facing intentional time delay of 0.3 to 0.5 seconds in both the
the front of the switchboard, panel, or box, and left to transfer and retransfer operations is built in to prevent
right when facing the rear of the switchboard, panel, or unnecessary transfer of power during line voltage surges
box. and very short duration losses of power.

BUS TRANSFER SWITCHES

Operation
Bus transfer equipment is used to provide two
sources of power to equipment that is vital to the ship. Table 3-1 lists the sequence of events in transferring
(NOTE: Vital equipment is that equipment needed to from the normal to the alternate source of power through
operate safely or that could cause the ship to become
the A-2 ABT switch:
disabled if it became de-energized.) Depending upon
the application, the transfer from one source to another
may be done manually, by a manual bus transfer switch,
or automatically by an automatic bus transfer switch.

Manual Bus Transfer (MBT)

Switches

When normal power to vital equipment is lost,

power must be restored as soon as possible to ensure the
safety of the ship. MBTs may be used to switch from
normal to alternate or emergency power for those loads
that draw a large starting current or that must meed some
condition before energizing.
By having a manual transfer of the power source,
the electrician on watch can make sure that all
conditions are met before energizing the equipment
after a loss of power.

Automatic Bus Transfer (ABT)

Switches

ABTs are used to provide two sources of power to

those loads that MUST be re-energized as soon as
possible. Examples of loads that must be re-energized
include lighting in main engineering spaces, the ship’s
steering motors and controls, motor driven fuel pumps
and lubricating oil pumps in the engineering spaces.
The Model A-2 ABT switch operates on 120-volt,
60Hz circuits. It is usually used to handle small
lighting circuits. It may be used on single- or Figure 3-4.—A pictorial view of the A-2 ABT.

3-4
 Figure 3-5.—Schematic diagram of the A-2 ABT.

Table 3-1.—Transfer from Normal to Emergency Power Upon restoration of the normal power supply, the
ABT automatically switches back through the sequence
of events in table 3-2:

Table 3-2.—Transfer from Emergency to Normal Power

3-5
Testing separation of sections provides greater protection from
damage since it is less likely that more than one unit can
When testing any ABT, make sure any vital or be damaged by one hit in battle. It also provides a means
sensitive loads fed from the ABT are isolated. This for removing a damaged section for repairs or
momentary interruption of power could damage replacement.
sensitive electronic circuitry. Therefore, before Switchboards provide three distinct functions
beginning testing an ABT, you must notify all aboard ship:
personnel concerned of the power supply system
interruptions. 1. The distribution of 450-volt, three-phase, 60Hz
power throughout the ship
SHIP’S SERVICE 2. The protection of distribution circuits
SWITCHBOARDS
3. The control, monitoring, and protection of the
Aboard modem Navy vessels, there are three gas turbine generator sets (GTGSs)
distinct groups or shipsets of distribution switchboards.
A shipset of main power distribution switchboards Capabilities
consists of three groups, each group being made up of
three units. Figures 3-6 through 3-8 show the Each switchboard group is an operationally
switchboards making up shipset 1S. independent system, capable of monitoring and
The units, physically separated and connected by controlling an associated generator. Because it is
cables, form a switchgear group. The physical operated as an independent system, a switchboard is
capable of distributing the power produced by the

Figure 3-6.—1S Ship’s service switchboard. Figure 3-7.—1SA Ship’s service switchboard.

3-6
 Figure 3-8.—1SB Ship’s service switchboard.

associated generator to equipment and zones fed by the Control and monitoring of the ship’s service power
switchboard bus. Operated in parallel with either one is accomplished by the various manual, remote, and
or both of the other groups, power can be supplied to the automatic control functions associated with the
entire ship’s service load. switchboards. In addition, the metering and indications
used to maintain proper power plant performance give
the electrician on watch the status of the power plant at
Description
any given time.

Power is produced by the GTGSs, inputted to the The distribution system is protected from damage
switchboards through the generator circuit breakers, and by the various mechanical and electrical devices used to
distributed to the various ships loads via feeder breakers interrupt the flow of electricity, either by command or
and load centers. automatically y, should a problem arise.

3-7
 The switchboards shown in figures 3-6, through connections, the bus bars, and the disconnect links
3-9 are representative of those found on most gas (fig. 3-9). Distribution of the generated power begins
turbine powered ships today, These switchboards with the switchboard. These switchboards can be
use sheet steel panels or enclosures from which only connected together through bus tie circuit breakers
the meters and the operating handles protrude to to forma continuous loop. This allows any two of the
the front. The rear handles protrude to the front. three GTGSs to supply the demand for power while
The rear panels can be removed to gain access to the third can be set up to start automatically in the
the internal components including the meter event of a power loss.

Figure 3-9.—Rear view of a switchboard showing bus bars and disconnect links.

3-8
 Figure 3-10.—Disconnect links.

Each of the switchboard units of a group are

connected together through disconnect links (fig. 3-10).
By removing the links between any two of the
switchboads, repairs or replacement of parts may be
accomplished without interfering with the operation of
the other units.

Control Equipment

Control of the electrical load can be accomplished

from the central control station (CCS) at the electric
plant control console (EPCC) (fig. 3-11) or by local
manual control at each GTGS and switchboard station.
The CCS and switchboard stations have the capabilities
of starting/stopping and distribution control. Only
start/stop control is available at the GTGS local control
panels.

Generator switchboards are equipped with

meters to indicate the generator voltage, current,
Figure 3-11.—Electric plant control console (EPCC).
power, frequency, and, in older ships, power factor

3-9
meters (fig. 3-12). Synchroscopes and synchronizing of the prime mover. The speed governors for large
lamps are provided for paralleling ac generators. Also, machines can be set to the required speed by a control
indicator lamps are provided to show the operating device mounted on the switchboard.
conditions of various circuits. When running in parallel with other generating a
The frequency is controlled by the generator speed, generator is prevented from operating as a motor by a
which is automatically controlled by the speed governor reverse power relay. The reverse power relay trips the

Figure 3-12.—EPCC showing distribution and system status and control sections.

3-10
generator breaker and takes the generator off the line
when power is fed from the line to the generator instead
of from the generator to the line.
A voltage regulator is mounted on each switchboard
and operates automatically to vary the field excitation
to maintain the generator voltage constant throughout
normal changes in load. In all installations, a means is
provided to manually adjust the voltage if the automatic
regulator fails.
Figure 3-13.—An ac ground detector lamp circuit.

Ground Detector Circuits

through conductors, or conductors passing through a
magnetic field.
A set of three ground detector lamps (fig. 3-13) is
connected through transformers to the main bus of each All generators have at least two distinct sets of
ship’s service switchgear group. It provides you with a conductors.
means to check for grounds on any phase of the
1. The armature winding, which consists of a
three-phase system. To check for a ground, turn switch
group of conductors in which the output voltage
Son and observe the brilliancy of the three lights, and
is generated.
look for the conditions shown below.
2. The field winding, which consists of a group of
conductors through which dc is passed to obtain
an electromagnetic field of fixed polarity.
Since relative motion is needed between the
armature and field flux, ac generators are built in two
major assemblies-the stator and the rotor. The rotor
rotates inside the stator. It is driven by several
commonly used power sources, such as gas or steam
turbines, electric motors, and internal-combustion
engines.

TYPES OF AC GENERATORS

There are various types of ac generators used today.

They all perform the same basic function. The types
discussed in this chapter are typical of the ones used in
shipboard electrical systems.

Revolving Armature

AC GENERATORS In the revolving-armature ac generator, the stator

provides a stationary electromagnetic field. The rotor,
Alternating-current generators produce most
acting as the armature, revolves in the field, cutting the
electric power used today. AC generators are also used
lines of force, thereby producing the desired output
in aircraft and automobiles.
voltage. In this generator, the armature output is taken
AC generators come in many different sizes, from slip rings, retaining its alternating characteristic.
depending on their intended use. For example, anyone
The use of the revolving-armature ac generator is
of the huge generators at Boulder Dam can produce
limited to low-power, low-voltage applications. The
millions of volt-amperes, while the small generators
primary reason for this limitation is its output power is
used on aircraft produce only a few thousand
conducted through sliding contacts (slip rings and
volt-amperes.
brushes). These contacts are subject to frictional wear
Regardless of their size, all generators operate on and sparking. In addition, they are exposed and liable
the same basic principle-a magnetic field cutting to arc-over at high voltages.

3-11
Revolving Field length of time. The rating of a generator is identified
very closely with its current capacity.
The rotating-field ac generator (fig. 3-14) is the
Temperature
most widely used type of generator. The rotating
magnetic field produced by the rotor extends outward
The rating of any electric device must take into
and cuts through the armature windings imbedded in the
account its allowable temperature rise; that is, the
surrounding stator. As the rotor turns, alternating
amount of rise in temperature (above ambient) the
voltages are induced in the windings since magnetic
machine can withstand and still be expected to operate
fields of first one polarity and then the other cut through
normally. The load rating of a particular generator is
them. Since the output power is taken from stationary
determined by the rise in temperature it can withstand,
windings, the output may be connected through fixed
caused primarily by the current flow. The rise in
terminals (T1 and T2 in fig. 3-14). This is helpful
temperature is caused by the losses of the generator. The
because there are no sliding contacts, and the whole
majority of losses are 12R losses in the armature
output circuit is continuously insulated, reducing the
windings.
danger of arc-over.
The maximum current that can be supplied by an ac
The rotating-field ac generator maybe constructed generator depends upon the following factors:
with or without brushes. In both types, dc from a
separate source is passed through windings on the rotor 1. The maximum heat loss (I2R power loss) that
to develop the rotating magnetic field. The source of dc cart be sustained in the armature, and;
may be a permanent magnet generator with its output 2. The maximum heat loss that can be sustained in
going to the rotor winding slip rings through a the field.
commutator (fig. 3-15, view A) or an alternator with its
output rectified by a silicon rectifier (fig. 3-15, view B) The armature current varies with the load and is
before being sent to the rotor. similar to that of dc generators. In ac generators,
lagging power factor loads tend to demagnetize the
Slip rings and brushes or silicon rectifier units are field. The terminal voltage is maintained only by an
adequate for the dc field supply because the power level increase in the dc field current. Therefore, ac generators
in the field is much smaller than in the armature circuit. are rated for armature load current and voltage output,
or kilovolt-ampere (kVA) output, at a specified
frequent y and power factor.
RATING OF AC GENERATORS

Power Factor
Alternators are rated according to the voltage and
current they are designed to produce. The normal load The power factor is an expression of the losses
rating is the load it cart carry continuous y. The overload within the electrical distribution system. It is
rating is the above normal load it cart carry for a specific determined by the amount the current and voltage sine
waves are out of phase, which is determined by the
characteristics of the total load seen on the circuit
(resistive, inductive, or capacitive). The power factor
can be found by using two methods:

Trigonometric Method Algebraic Method

Determine the angle of lead Determine true power (kW)

or lag between voltage and consumed by load from
current wattmeter

Power factor is cosine of Determine apparent power

phase angle (kVA) consumed by load
by multiplying line voltage
and current from meters on
swbd

Power Factor = kW/kVA

Figure 3-14.—Essential parts of a rotating-field generator.

3-12
 Figure 3-15.—An ac generator: A. Brush type. B. Brushless type.

The specified power factor is usually 80 percent this ac generator were to supply a 100-kVA load at 20%
power factor, the required increase in dc field current
lagging. For example, a single-phase ac generator
needed to maintain the desired terminal voltage would
designed to deliver 100 A at 1,000 V is rated at 100 kVA.
cause excessive heating in the field.
his machine will supply a 100-kW load at unity power
factor or an 80-kW load at 80 percent power factor. If

3-13
 Figure 3-16.—Low-speed, engine-driven ac generator.

CONSTRUCTION AND OPERATION OF AC only directs the paths of the circulating, air-cooling
GENERATOR SETS currents, it also reduces windage noise.

Many of today’s modern ship’s utilize gas turbine

AC generator sets maybe divided into the following units to provide power for propulsion and generating
two classes according to the speed of the generator:

1. Low speed, engine driven

2. High speed, turbine driven

The stator, or armature, of the revolving-field ac

generator is made of steel punchings called laminations.
The laminations of an ac generator stator form a steel
ring keyed or bolted to the inside circumference of a
steel frame. The inner surface of the laminated ring has
slots in which the stator winding is placed.

A low-speed, engine-driven ac generator (fig. 3-16)

has a large-diameter revolving field with many poles and
a stationary armature that is relatively short in axial
length. The stator contains the armature windings. The
rotor consists of salient poles, on which are mounted the
do field windings.

The high-speed, turbine-driven ac generator (fig. 3-

17) is connected to a turbine either directly or through
gears. The enclosed metal structure is a part of a forced
ventilation system that carries away the heat by
circulation of the air through the stator (fig. 3-17, view
A) and the rotor (fig. 3-17, view B). (The exciter is a
Figure 3-17.—High-speed, steam turbine-driven ac
separate unit and is not shown.) The enclosed stator not
generator.

3-14
 Figure 3-18.—Model 104 gas turbine generator set.

electrical power. The gas turbine units (fig. 3-18) are generator through the rotor drive shaft (1) (view A). The
small, efficient, easily replaed, and simple to operate. exciter shunt field (2) (view B) creates an area of intense
While Gas Turbine Specialist’s (GS’s) are primarily magnetic flux between its poles. When the exciter
responsible for maintenance on the unit itself, EM’s
often stand electrical watch on the units.

Basic Functions of Generator Parts

A typical rotating-field ac generator consists of an

ac generator and a smaller dc generator built into a single
unit. The ac generator section supplies alternating
current to the load for which the generator was designed.
The dc generator supplies the direct current required to
maintain the ac generator field. This dc generator is
referred to as the exciter. Atypical ac generator is shown
in figure 3-19, view A. Figure 3-19, view B, is a
simplified schematic of the generator. The parenthetical
numbers in the following paragraph are indicated on
figure 3-19.

Operation

Any rotary generator (fig. 3-19) requires a prime

moving force to rotate the ac field and exciter armature.
This rotary force is usually furnished by a combustion
engine, turbine, or electric motor and transmitted to the Figure 3-19.—An ac generator and schematic.

3-15
armature (3) is rotated in the exciter field flux, voltage Wye Connection
is induced into the exciter armature windings. The
Rather than have six leads come out of the three-
exciter output commutator and brushes (4) connect the
phase ac generator, one of the leads from each phase is
exciter output directly to the ac generator field input slip
connected to form a common junction. The stator is
rings and brushes (5). Since slip rings, rather than a
then said to be wye, or star, connected. The common
commutator, are used to supply current through the ac
lead may or may not be brought out of the machine, If
generator field (6), current always flows in one direction
it is brought out, it is called the neutral. A simplified
through these windings. Thus, a fixed polarity magnetic
schematic (fig. 3-20, view B) shows a wye-connected
field is maintained at all times in the ac generator field
stator with the common lead not brought out. Each load
windings. When the ac generator field is rotated, its
is connected across two phases in series as follows:
magnetic flux is passed through and across the ac
generator armature windings (7). A voltage is induced
• RAB is connected across phases A and B in series
into the stator windings by the relative motion of the
magnetic lines of flux cutting across and through the • WAC is connected across phases A and C in series
windings in the stator. The alternating voltage induced
in the ac generator armature windings is connected • RBC is connected across phases B and C in series
through fixed terminals to the ac load. Thus, the voltage across each load is larger than the volt-
age across a single phase. In a wye-connected ac gen-
THREE-PHASE GENERATORS erator, the three start ends of each single-phase winding
are connected together to a common neutral point, and
As the name implies, a three-phase ac generator has the opposite, or finish, ends are connected to the line
three single-phase windings spaced so that the voltage terminals, A, B, and C. These letters are always used to
induced in each winding is 120° out of phase with the designate the three phases of a three-phase system or the
voltages in the other two windings. A schematic three line wires to which the ac generator phases connect.
diagram of a three-phase stator showing all the coils
A three-phase, wye-connected ac generator
becomes complex, and it is difficult to see what is
supplying three separate loads is shown in figure 3-21.
actually happening. A simplified schematic diagram
When unbalanced loads are used, a neutral may be
showing all the windings of a single phase lumped
added as shown in the figure by the broken line between
together as one winding is shown in figure 3-20, view
the common neutral point and the loads. The neutral
A. The rotor is omitted for simplicity. The waveforms
wire serves as a common return circuit for all three
of voltage are shown to the right of the schematic. The
phases and maintains a voltage balance across the loads.
three voltages are 120° apart and are similar to the
No current flows in the neutral wire when the loads are
voltages that would be generated b y three, single-phase
balanced. This system is a three-phase, four-wire circuit
ac generators whose voltages are out of phase by angles
and is used to distribute three-phase power to
of 120°. The three phases are independent of each other.
shore-based installations. The three-phase, four-wire
system is not generally used aboard ship, but it is widely
used in industry and in aircraft ac power systems.

Delta Connection
A three-phase stator may also be connected as
shown in figure 3-22. This type of connection is called

Figure 3-21.—Three-phase, ac generator showing neutral

Figure 3-20.—Three-phase ac generator. connection.

3-16
 Figure 3-22.—Three-phase, delt-connected system.
the delta connection. In a delta-connected ac generator,
the connections are made as follows:

• The start end of one phase winding is connected

to the finish end of the third.

• The start of the third phase winding is connected Figure 3-23.—Waves and vectors of alternating current and
voltage in a circuit containing only resistance.
to the finish of the second phase winding.
The magnitude of a vector is represented by its
• The start of the second phase winding is
length: the longer the vector, the higher its magnitude.
connected to the finish of the first phase winding.
The direction in which the vector acts is shown by the
The three junction points are connected to the line wires direction of the arrow.
leading to the load.
Alternating current and voltage vectors are
The three-phase, delta-connected ac generator is referenced to a coordinate plane, which represents 360
connected to a three-phase, three-wire circuit, which electrical degrees. By agreement, counterclockwise
supplies a three-phase, delta-connected load at the rotation represents positive and clockwise rotation
right-hand end of the three-phase line. Because the represents negative. The horizontal axis of an analysis
phases are connected directly across the line wires, diagram represents the reference axis, and any vectors
phase voltage is equal to line voltage. When the in the diagram are referenced to this position.
generator phases are properly connected in delta, no In figure 3-23, you can that the voltage (E) and the
appreciable current flows within the delta loop when current (I) are in phase with one another. Since the two
there is no external load connected to the generator. If values are in phase, the angle between them is 0 in the
any one of the phases is reversed with respect to its vector diagram. This represents a purely resistive ac
correct connection a short-circuit current flows within circuit.
the windings of no load, causing damage to the
Look at figure 3-24. Here, you can see that the
windings.
voltage (E) is leading the current (1) by degrees. You
Vector Analysis
A scalar quantity has only one facet, magnitude. On
the other hand, a vector quantity has more than one facet,
as shown by a vector diagram. In the vector diagram,
the vector is shown by a line drawn to scale with an
arrow head to indicate direction. This line showing a
vector quantity indicates both magnitude and direction.
Good examples of both quantities are shown below:

Figure 3-24.—Waves and vectors of alternating current and

voltage in a circuit containing only inductance.

3-17
 to rotate in a direction that three-phase voltages are
generated in the following order: Ea, Eb, and Ec.
The voltage in phase b, or Eb, lags the voltage in
phase a, or E a, by 120°. Likewise, Ec lags Eb by 120°,
and Ea lags Ec by 120°. In figure 3-26, the arrows, Ea,
Eb, and Ec, represent the positive direction of generated
voltage in the wye-connected ac generator. The arrows,
I1, I2, and I3, represent the positive direction of phase
and line currents supplied to balance unit power-factor
loads connected in wye. The three voltmeters
connected between lines 1 and 2, 2 and 3, and 3 and 1
indicate effective values of line voltage. The line
voltage is greater than the voltage of a phase in the
Figure 3-25.—Waves and vectors of alternating current and w ye-connected circuit because there are two phases
voltage in a circuit containing only capacitance. connected in series between each pair of line leads, and
their voltages combine. However, line voltage is not
can remember this by the memory hint ELI —voltage twice the value of phase voltage because the phase
leads current in an inductive circuit). Since voltage voltages are out of phase with each other.
is leading current, the vector diagram shows voltage in
The relationship between the phase and the line
a counterclockwise or positive direction from current. voltages is shown in the vector diagram (fig. 3-27).
Now, look at figure 3-25, which shows the current Effective values of phase voltage are indicated by
(I) leading the voltage (E) by degrees. Using the vectors Ea, Eb, and Ec. Effective values of line and
memory hint ICE— current leads voltage in a phase current are indicated by vectors Ia, Ib, and Ic.
capacitive circuit —you can remember this vector. Because there is only one path for the current between
any given phase and the line lead to which it is
Since current leads voltage by degrees, the vector
connected, the phase current is equal to the line current.
representing voltage is in a clockwise or negative
The respective phase currents have equal values because
direction from the vector representing current.
the load is assumed to be balanced. For the same reason,
Analysis of Wye Connected Stators the respective line currents have equal values. When the
load has unity power factor, the phase currents are in
The phase relationships in a three- wire, three-phase,
phase with their respective phase voltages.
wye-connected system are shown in figure 3-26. In
constructing vector diagrams of three-phase circuits, a In combining ac voltages, it is important to know
counterclockwise rotation is assumed in order to the direction in which the positive maximum values of
maintain the correct phase relation between line the voltages act in the circuit as well as the magnitudes
voltages and currents. Thus, the ac generator is assumed of the voltages. (NOTE: As you read this section, look

Figure 3-26.—Three-phase, wye-connected system.

3-18
at figure 3-27.) For example, in view A, the positive In equation form: If Ea and Eb are each 100 volts,
maximum voltage generated in coils A and B act in the then
direction of the arrows, and B leads A by 120°. This
arrangement may be obtained by assuming coils A and
B to be two armature windings located 120° apart. If
The value of Er may be derived as follows:
each voltage has an effective value of 100 volts, the total
voltage is Er = 100 volts, as shown by the polar vectors 1. Erect a perpendicular to Er divides the isosceles
in view B. triangle into two equal right triangles.
If the connections of coil B are reversed (view C) 2. Each right triangle has a hypotenuse of 100 volts
with respect to their original connections, the two and abase of 100 cos 30°, or 86.6 volts.
voltages are in opposition. You can see this by tracing
3. The total length of Er is 2 x 86.6, or 173.2 volts.
the circuit in the direction of the arrow in coil A.
To construct the line voltage vectors E1,2, E2,3, and
1. The positive direction of the voltage in coil B is E3,1, in figure 3-26, it is first necessary to trace a path
opposite to the direction of the trace around the closed circuit that includes the line wires,
2. The positive direction of the voltage generated armature windings, and one of the three voltmeters. For
in coil A is the same as that of the trace. example, in figure 3-21, consider the circuit that
Therefore, the two voltages are in opposition. includes the upper and middle wires, the voltmeter
connected across them, and the ac generator phases a
3. This effect is the same as though the positive
and b. The circuit trace is started at the center of the
maximum value of Eb were 60° out of phase
wye, proceeds through phase a of the ac generator, out
with that of E a, and Eb acted in the same
line 1, down through the voltmeter from line 1 to line 2,
direction as& when the circuit trace was made
and through phase b of the ac generator back to the
(view D) to vector. starting point. Voltage drops along line wires are
4. Ea is accomplished by reversing the position of disregarded. The voltmeter indicates an effective value
Eb from that shown in view B, to the position equal to the vector sum of the effective value of voltage
shown in view D, which completes the in phases a and b. This value is the line voltage, E1,2.
parallelogram. According to Kirchhoff’s law, the source voltage

Figure 3-27.—Vector analysis of voltage in series aiding and opposing.

3-19
between lines 1 and 2 equals the voltage drop across the The line voltages (E1,2, E2,3, and E3,1) are the
voltmeter connected to these lines. diagonals of three parallelograms whose sides are the
phase voltages E a, Eb, and Ec. From this vector
If the direction of the path traced through the
diagram, the following facts are observed:
generator is the same as that of the arrow, the sign of the
voltage is plus; if the direction of the trace is opposite to 1. The line voltages are equal and 120° apart.
the arrow, the sign of the voltage is minus. If the
2. The line currents are equal and 120° apart.
direction of the path traced through the voltmeter is the
same as that of the arrow, the sign of the voltage is 3. The line currents are 30° out of phase with&
minus; if the direction of the trace is opposite to that of line voltages when the power factor of the load
the arrow, the sign of the voltage is plus. is 100%.
4. The line voltage is the product of the phase
The following equations for voltage are based on
voltage and the
the preceding explanation:

E a + (-Eb) = E1,2, or E1,2 = Ea - Eb Analysis of Delta-Connected Stators

E b + (-Ec) = E2,3, or E2,3 = Eb- Ec The three-phase currents, Ia, Ib, and Ic, are indicated
E c + (Ea) = E3,1, or E3,1 = Ec - Ea by accompanying arrows in the generator phases in
figure 3-22. These arrows point in the direction of the
The signs + and – mean vector addition and vector
positive current and voltage of each phase. The three
subtraction, respective y. One vector is subtracted from
voltmeters connected across lines 1 and 2, 2 and 3, and
another by reversing the position of the vector to be
3 and 1, respectively, indicate effective values of line
subtraced through an angle of 180° and constructing a
and phase voltage. Line current 11 is supplied by phases
parallelogram, the sides of which are the reversed vector
a and c, which are connected to line 1. Line current is
and the other vector. The diagonal of the parallelogram
greater than phase current, but it is not twice as great
is the difference vector.
because the phase currents are not in phase with each
These equations are applied to the vector diagram other. The relationship between line currents and phase
of figure 3-26. They are used, to derive the line voltages. currents is shown in figure 3-28.

Figure 3-28.—Three-phase delta/connected system.

3-20
 Effective values of line and phase voltages are Example 2: A three-phase, delta-connected ac
indicated in figure 3-28 by vectors Ea, Eb, and Ec. Note generator has a terminal voltage of 450 volts, and the
that the vector sum of Ea, Eb, and Ec is zero. The phase current in each phase is 200 amperes. The power factor
currents are equal to each other because the loads are of the load is 75 percent. Find (a) the line voltage, (b)
balanced. The line currents are equal to each other for the line current, (c) the apparent power, and (d) the true
the same reason. At unity-power-factor loads, the phase power.
current and phase voltage have a 0-degree angle
between them.

The power delivered by a balanced, three-phase,

delta-connected system is also three times the power
delivered by each phase. Mathematically, you can
prove this as follows:

Because

the total true power is

MEASUREMENT OF POWER

The wattmeter connections for measuring the true

power in a three-phase system are shown in figure 3-29.
The method shown in figure 3-29, view A, uses three
Thus, the expression for three-phase power delivered by wattmeters with their current coils inserted in series with
a balanced delta-connected system is the same as the the line wires and their potential coils connected
expression for three-phase power delivered by a between line and neutral wires. The total true power is
balanced wye-connected system. Two examples are equal to the arithmetic sum of the three wattmeter
given to illustrate the phase relations between current, readings.
voltage, and power in (1) a three-phase, wye-connected The method shown in figure 3-29, view B, uses two
system and (2) a three-phase, delta-connected system. wattmeters with their current coils connected in series
Example 1: A three-phase, wye-connected ac
generator has a terminal voltage of 450 volts and
delivers a full-load current of 300 amperes per terminal
at a power factor of 80 percent. Find (a) the phase
voltage, (b) the full-load current per phase, (c) the
kilovolt-ampere, or apparent power, rating, and (d) the
true power output.

Figure 3-29.—Wattmeters.

3-21
with two line wires and their potential coils connected
between these line wires and the common, or third, wire
that does not contain the current coils. The total true
power is equal to the algebraic sum of the two wattmeter
readings. If one meter reads backward, its potential coil GENERATED VOLTAGE
connections are first reversed to make the meter read
upscale, and the total true power is then equal to the Generated voltage of a generator is expressed by the
difference in the two wattmeter readings. If the load formula:
power factor is less than 0.5 and the loads are balanced,
the total true power is equal to the difference in the two
wattmeter readings. If the load power factor is 0.5, one
meter indicates the total true power and the other Where:
indicates zero. If the load power factor is above 0.5, the Eg is generated voltage
total true power is equal to the sum of the two wattmeter
K is a constant determined by the construction of
readings.
the generator

FREQUENCY is the strength of the rotating magnetic field

N is the synchronous speed
The frequency of the ac generator voltage depends Its impractical to vary the frequency of power
upon the speed of rotation of the rotor and the number supplied throughout the ship in order to regulate the
of poles. The faster the speed the higher the frequency. voltage generated, and the constant can’t be changed
Conversely, the lower the speed, the lower the once the machine has been designed and built; therefore,
frequency. The more poles there are on the rotor, the the generated voltage of an ac generator is controlled by
higher the frequency is for a given speed. When a rotor varying the dc excitation voltage applied to the rotor
has rotated through an angle so that two adjacent rotor field winding thus varying
poles (a north and a south pole) have passed one
winding, the voltage induced in that winding will have
modulated through one complete cycle. For a given GENERATOR CHARACTERISTICS
frequency, the more pairs of poles, the lower the
speed of rotation. A two-pole generator rotates at twice When the load on a generator is changed, the
the speed of a four-pole generator for the same terminal voltage varies with the load. The amount of
frequency of generated voltage. The frequency of the variation depends on the design of the generator and the
generator in Hz (cycles per second) is related to the power factor of the load. With a load having a lagging
number of poles and the speed as expressed by the power factor, the drop in terminal voltage with increased
equation load is greater than for unity power factor. With a load
having a leading power factor, the terminal voltage tends
to rise. The causes of a change in terminal voltage with
load change are:
where P is the number of poles and N the speed in rpm.
• armature resistance,
For example, a two-pole, 3,600-rpm generator has a
frequency of • armature reactance, and

• armature reaction.

a four-pole 1,800-rpm generator has the same Armature Resistance

frequency; a six-pole, 500-rpm generator has a
frequency of When current flows through a generator armature
winding, there is an IR drop due to the resistance of the
winding. This drop increases with load, and the
terminal voltage is reduced. The armature resistance
and a 12-pole, 4,000-rpm generator has a frequency of drop is small because the resistance is low.

3-22
Armature Reactance IR drop lag the terminal voltage by angle In this
example, the armature IZ drop is more nearly in phase
The armature current of an ac generator varies with the terminal voltage and the generated voltage.
approximately as a sine wave. The continuously Hence, the terminal voltage is approximately equal to
varying current in the generator armature is the generated voltage, less the armature IZ drop.
accompanied by an IXL voltage drop in addition to the Because the IZ drop is much greater than the IR drop,
IR drop. Armature reactance in an ac generator may be the terminal voltage is reduced that much more. The
from 30 to 50 times the value of armature resistance volt age vectors for a leading power-factor load are
because of the relatively large inductance of the coils shown in figure 3-30, view C. The load current and IR
compared with their resistance. drop lead the terminal voltage by angle This
condition results in an increase in terminal voltage
A simplified series equivalent circuit of one phase
above the value of EG. The total available voltage of
of an ac generator is shown in figure 3-30. The voltage
the ac generator phase is the combined effect of E C
generated in the phase winding is equal to the vector sum
(rotational y induced) and the self-induced voltage (not
of the terminal voltage for the phase and the internal
shown in the vectors). The self-induced voltage, as in
voltage loss in the armature resistance, R, and the
any ac circuit, is caused by the varying field
armature reactance, XL, associated with that phase. The
(accompanying the varying armature current) linking
voltage vectors for a unity power-factor load are shown
the armature conductors. The self-induced voltage
in figure 3-30, view A. The armature IR drop is in phase
always lags the current by 90°; hence, when I leads E T,
with the current, I, and the terminal voltage, ET.
the self-induced voltage aids EG, and ET increases.
Because the armature IXL drop is 90° out of phase with
the current, the terminal voltage is approximate] y equal
Armature Reaction
to the generated voltage, less the IR drop in the armature.

The voltage vectors for a lagging power-factor load When an ac generator supplies no load, the dc field
are shown in figure 3-30, view B. The load current and flux is distributed uniformly across the air gap. When

Figure 3-30.—The ac generator voltage characteristics.

3-23
an ac generator supplies a reactive load, however, the windings, or a single secondary with several tap
current flowing through the armature conductors connections. These transformers have a low
produces an armature magnetomotive force (mmf) that volt-ampere capacity and are less efficient than large
influences the terminal voltage by changing the constant-potential power transformers. Most
magnitude of the field flux across the air gap. When the power-supply transformers for electronic equipment are
load is inductive, the armature mmf opposes the dc field designed to operate at a frequency of 50 to 60 Hz.
and weakens it, thus lowering the terminal voltage. Aircraft power-supply transformers are designed for a
When a leading current flows in the armature, the dc frequency of 400 Hz. The higher frequencies permit a
field is aided by the armature mmf, and the flux across saving in size and weight of transformers and associated
the air gap is increased, thus increasing the terminal equipment.
voltage.
CONSTRUCTION
TRANSFORMERS
The typical trzansformer has two windings insulated
A transformer is a device that has no moving parts electrically from each other. These windings are wound
and that transfers energy from one circuit to another by on a common magnetic core made of laminated sheet
electromagnetic induction. The energy is always steel. The principal parts of a transformer and their
transferred without a change in frequency, but usually functions areas follows:
with changes in voltage and current. A step-up
transformer receives electrical energy atone voltage and Piece Function
delivers it at a higher voltage, Conversely, a step-down
transformer receives energy at one voltage and delivers Core Provides a path for the magnetic
it at a lower voltage. Transformers require little care and lines of flux
maintenance because of their simple, rugged, and
durable construction. The efficiency of transformed is Primary winding Receives the energy from the ac
high. Because of this, transformers are responsible for source
the more extensive use of alternating current than direct
current. The conventional constant-potential Secondary winding Receives energy from the
transformer is designed to operate with the primary primary winding and delivers it
connected across a constant-potential source and to to the load
provide a secondary voltage that is substantially
constant from no load to full load. Enclosure Protects the above components
from dirt, moisture, and
Various types of small, single-phase transformers mechanical damage
are used in electrical equipment. In many installations,
transformers are used on switchboards to step down the
voltage for indicating lights. Low-voltage transformers When a transformer is used to step up the voltage,
are included in some motor control panels to supply the low-voltage winding is the primary. Conversely,
control circuits or to operate overload relays, when a transformer is used to step down the voltage, the
high-voltage winding is the primary. The primary is
Instrument transformers include potential, or
always connected to the source of the power; the
voltage, transformers and current transformers.
secondary is always connected to the load It is common
Instrument transformers are commonly used with ac
practice to refer to the windings as the primary and
instruments when high voltages or large currents are to
secondary rather than the high-voltage and low-voltage
be measured.
windings.
Electronic circuits and devices employ many types
There are two principal types of transformer
of transformers to provide the necessary voltages for
construction—the core type and the shell type (fig. 3-31,
proper electron-tube operation, interstage coupling,
views A and B). The cores are built of thin stampings
signal amplification, and so forth. The physical
of silicon steel. Eddy currents, generated in the core by
construction of these transformers differs widely.
the alternating flux as it cuts through the iron, are
Power-supply transformers, used in electronic minimized by using thin laminations and by insulating
circuits, are single-phase, constant-potential adjacent laminations with insulating varnish.
transformers with either one or more secondary Hysteresis losses, caused by the friction developed

3-24
 Figure 3-31.—Types transformer construction.

between magnetic particles as they are rotated through drop, half of each winding is placed on each leg of the
each cycle of magnetization, are minimized by the use core. The windings may be cylindrical in form and
of a special grade of heat-treated, grain-oriented, placed one inside the other with the necessary
silicon-steel laminations. insulation, as shown in figure 3-31, view A. The
In the core type of transformer, copper windings low-voltage winding is placed with a large part of its
surround the laminated iron core. In the shell type of surface area next to the core, and the high-voltage
transformer, an iron core surrounds the copper winding is placed outside the low-voltage winding in
windings. Distribution transformers are generally of the order to reduce the insulation requirements of the two
core type, whereas some of the largest power windings. If the high-voltage winding were placed next
transformers are of the shell type.
to the core, two layers of high-voltage insulation would
If the windings of a core-type transformer were be required, one next to the core and the other between
placed on separate legs of the core, a relatively large the two windings.
amount of the flux produced by the primary winding
In another method, the windings are built up in thin,
would fail to link the secondary winding and a large
leakage flux would result. The effect of the leakage flux flat sections called pancake coils. These pancake coils
would be to increase the leakage reactance drop, IXL, in are sandwiched together with the required insulation
both windings. To reduce the leakage flux and reactance between them, as shown in figure 3-31, view B.

3-25
 The complete core and coil assembly (fig. 3-32, where, E1 and E2 are the induced voltages in the
view A) is placed in a steel tank. In some transformers, primary and secondary windings, and
the complete assembly is immersed in a special mineral
N 1 and N2 are the number of turns in the
oil to provide a means of insulation and cooling, while
primary and secondary windings.
in other transformers they are mounted in dripproof
enclosures, as shown in figure 3-32, view B. In ordinary transformers, the induced primary
voltage is almost equal to the applied primary
Transformers are built in both single-phase and voltage; hence, the applied primary voltage and the
polyphase units. A three-phase transformer consists of secondary induced voltage are approximately
separate insulated windings for the different phases, proportional to the respective number of turns in the two
which are wound on a three-legged core capable of windings.
establishing three magnetic fluxes displaced 120° in
time phase. A constant-potential, single-phase transformer is
represented by the schematic diagram in figure 3-33,
VOLTAGE AND CURRENT RELATIONSHIPS view A. For simplicity, the primary winding is shown
The operation of the transformer is based on the as being on one leg of the core and the secondary
principle that electrical energy can be transferred ef- winding on the other leg. The equation for the voltage
ficiently by mutual induction from one winding to another. induced in one winding of the transformer is
When the primary winding is energiaed from an ac source,
an alternating magnetic flux is established in the
transformer core. This flux links the turns of both primary
and secondary, thereby inducing voltages in them. where:
Because the same flux cuts both windings, the same
voltage is induced in each turn of both windings. Hence, E is the rms voltage
the total induced voltage in each winding is proportional B is the maximum value of the magnetic flux
to the number of turns in that winding; that is, density in lines per square inch in the core
S is the cross-sectional area of the core in square
inches

Figure 3-32.—Single-phase transformer.

3-26
 Figure 3-33.—Constant-potential transformer.

f is the frequency in hertz, and produces the transformer core flux The flux produced
by 1. cuts the primary winding, N1, and induces a
N is the number of complete turns in the winding
counter voltage, Ec, 180° out of phase with E1 in this
For example, if the maximum flux density is 90,000 winding. The voltage, E2, induced in the secondary
lines per square inch, the cross-sectional area of the core winding is in phase with the induced (counter) voltage,
is 4.18 square inches, the frequency is 60 Hz, and the E., in the primary winding, and both lag the exciting
number of turns in the high-voltage winding is 1,200, current and flux, whose variations produce them, by an
the voltage rating of this winding is angle of 90°. These relations are shown in vector form
in figure 3-33, view C. The values are only approximate
and are not drawn exactly to scale.
When a load is connected to the secondary by
If the primary-to-secondary turns ratio of this closing switch S (fig. 3-33, view A), the secondary
transformer is 10 to 1, the number of turns in the current, I2, depends upon the magnitude of the
low-voltage winding will be secondary voltage, E2, and the load impedance, Z. For
example, if E2 is equal to 120 volts and the load
impedance is 20 ohms, the secondary current will be

and the voltage induced in the secondary will be

If the secondary power factor is 86.6 percent, the

For a more in-depth explanation of voltage and phase angle, between secondary current and voltage
current relations, refer to NEETS, Module 2, will be the angle whose cosine is 0.866, or 30°.
Introduction to Alternating Current and Transformers,
The secondary load current flowing through the
NAVEDTRA 172-02-00-88, Topic 5, Transformers.
secondary turns comprises a load component of
The waveforms of the ideal transformer with no magnetomotive force, which, according to Lenz’s law,
load are shown in figure 3-33, view B. When E1 is is in such a direction as to oppose the flux that is
applied to the primary winding, N1, with the switch, S, producing it. This opposition tends to reduce the
open, the resulting current, Ia, is small and lags E1 by transformer flux a slight amount. The reduction in flux
almost 90° because the circuit is highly inductive. This is accompanied by a reduction in the counter voltage
no-load current is called the exciting, or magnetizing, induced in the primary winding of the transformer.
current because it supplies the magnetomotive force that Because the internal impedance of the primary winding

3-27
is low and the primary current is limited principally by output. For example, a transformer having a full-load
the counter emf in the winding, the transformer primary rating of 100 kVA can supply a 100-kW load at a unity
current increases when the counter emf in the primary power factor, but only an 80-kW load at a lagging power
is reduced. factor of 80 percent.
The increase in primary current continues until the Many transformers are rated in terms of the kVA
primary ampere-turns are equal to the secondary load that they can safely carry continuously without
ampere-turns, neglecting losses. For example, in the exceeding a temperature rise of 80°C when maintaining
transformer being considered, the magnetizing current, rated secondary voltage at rated frequency and when
Ia, is assumed to be negligible in comparison with the operating with an ambient (surrounding atmosphere)
total primary current, I1 + I a, under load conditions temperature of 40°C. The actual temperature rise of any
because Ia is small in relation to I1 and lags it by an angle part of the transformers the difference between the total
of 60°. Hence, the primary and secondary ampere-turns temperature of that part and the temperature of the
are equal and opposite; that is, surrounding air.
It is possible to operate transformers on a higher
frequency than that for which they are designed, but it
In this example, is not permissible to operate them at more than 10
percent below their rated frequency because they will
overheat. The exciting current in the primary varies
directly with the applied voltage and, like any
Neglecting losses, the power delivered to the primary is impedance containing inductive reactance, the exciting
equal to the power supplied b the secondary to the load. current varies inversely with the frequency. Thus, at
If the load power is P 2 = E21 2 cos and cosine reduced frequency, the exciting current becomes
2
equals cosine 30° (0.866), then P = 120 x 6 x 0.866= excessively large, and the accompanying heating may
624 watts. damage the insulation and the windings.

The load component of primary current, 11, EFFICIENCY

increases with secondary load and maintains the
transformer core flux at nearly its initial value. This The efficiency of a transformer is the ratio of the
action enables the transformer primary to take power output power at the secondary terminals to the input
from the source in proportion to the load demand, and power at the primary terminals. It is also equal to the
to maintain the terminal voltage approximately ratio of the output to the output plus losses. That is,
constant. The lagging power-factor load vectors are
shown in figure 4-31, view D. Note that the load power
factor is transferred through the transformer to the
primary and that is approximately equal to the
only difference being that is slightly larger than
because of the presence of the exciting current, which
flows in the primary winding but not in the secondary. The ordinary power transformer has an efficiency
of 97 to 99 percent. The losses are due to the copper
The copper loss of a transformer varies as the square losses in both windings and the hysteresis and
of the load current; whereas the core loss depends on the eddy-current losses in the iron core.
terminal voltage applied to the primary and on the
The copper losses vary as the square of the current
frequency of operation. The core loss of a
in the windings and as the winding resistance. In the
constant-potential transformer is constant from no load
transformer being considered, if the primary has l,200
to full load because the frequency is constant and the
turns of number 23 copper wire, having a length of 1,320
effective values of the applied voltage, exciting current,
feet, the resistance of the primary winding is 26.9 ohms.
and flux density are constant.
If the load current in the primary is 0.5 ampere, the
If the load supplied by a transformer has a unity primary copper loss is (0.5)2 x 26.9 = 6.725 watts.
power factor, the kilowatt (true power) output is the Similarly, if the secondary winding contains 120
same as the kilovolt-ampere (apparent power) output. turns of number 13 copper wire, having a length
If the load has a lagging power factor, the kilowatt of approximately 132 feet, the secondary resistance will
output is proportionally less than the kilovolt-ampere be 0.269 ohm. The secondary copper loss is I2R 2, or

3-28
(5)2 x 0.269= 6.725 watts, and the total copper loss is add. For example, if each secondary winding is rated at
6.725 x 2 – 13.45 watts. 120 volts and 100 amperes, the series-connection output
rating will be 240 volts at 100 amperes, or 24 kVA; the
The core losses, consisting of the hysteresis and parallel-connection output rating will be 120volts at 200
eddy-current losses, caused by the alternating magnetic amperes, or 24 kVA.
flux in the core are approximate] y constant from no load
to full load with rated voltage applied to the primary. In the series connection, care must be taken to
connect the coils so their voltages add. The proper
In the transformer of figure 3-33, view A, if the core arrangement is indicated in figure 3-34, view A. A trace
loss is 10.6 watts and the copper loss is 13.4 watts, the made through the secondary circuits from X1 to X4 is
efficiency is in the same direction as that of the arrows representing
the maximum positive voltages.

In the parallel connection, care must be taken to

connect the coils so their voltages are in opposition. The
correct connection is indicated in figure 3-34, view B.
The direction of a trace made through the secondary
or 96.3 percent. The rating of the transformer is windings from X1 to X2 to X4 to X3 and returning to
X1 is the same as that of the arrow in the right-hand
winding. This condition indicates that the secondary
voltages have their positive maximum values in
The efficiency of this transformer is relatively low directions opposite to each other in the closed circuit,
because it is a small transformer and the losses are which is formed by paralleling the two secondary
disproportionately large. windings. Thus, no circulating current will flow in these
windings on no load. If either winding were reversed,
CONNECTIONS a short-circuit current would flow in the secondary, and
this would cause the primary to draw a short-circuit
In this section we will discuss the differences current from the source. This action would, of course,
encountered when dealing with transformer windings damage the transformer as well as the source.
connected for single- and three-phase operation.
Three-Phase Connections
Single-Phase Connections
Power may be supplied through three-phase circuits
Single-phase distribution transformers usually have containing transformers in which the primaries and
their windings divided into two or more sections, as secondaries are connected in various wye and delta
shown in figure 3-34, view A. When the two secondary combinations. For example, three single-phase
windings are connected in series (fig. 3-34, view A), transformers may supply three-phase power with four
their voltages add. When two secondary windings are possible combinations of their primaries and
connected in parallel (fig. 3-34, view B), their currents secondaries. These connections are

1. primaries in delta and secondaries in delta,

2. primaries in wye and secondaries in wye,
3. primaries in wye and secondaries in delta, and
4. primaries in delta and secondaries in wye.
Earlier under the heading Three-Phase Generators,
delta and wye connections were discussed. Also
discussed was the phase relationship between line and
phase voltages and that current is the same as in ac
generators.

If the primaries of three single-phase transformers

are properly connected (either in wye or delta) to a
Figure 3-34.—Single-phase transformer connections. three-phase source, the secondaries may be connected

3-29
in delta, as shown in figure 3-35. A topographic vector the indication should be approximately zero. Then, the
diagram of the three-phase secondary voltages is shown delta is completed by connecting the X2 lead to A and
in figure 3-35, view A. the vector sum of these three the X1 lead to B.
voltages is zero. This may be seen by combining any
If the three secondaries of an energized transformer
two vectors, for example, EA and EB, and noting that
bank are properly connected in delta and are supplying
their sum is equal and opposite to the third vector, Ec.
a balanced three-phase load the line current will be
When the windings are connected properly, a voltmeter
equal to 1.73 times the phase current. If the rated current
inserted within the delta will indicate zero voltage, as
of a phase (winding) is 100 amperes, the rated line
shown in figure 3-35, view B.
current will be 173 amperes. If the rated voltage of a
Assuming all three transformers have the same phase is 120 volts, the voltage between any two line
polarity, the delta connection consists of connecting the wires will be 120 volts.
X2 lead of winding A to the X1 lead of B, the X2 lead
of B to X1 of C, and the X2 lead of C to X1 of A. If any The three secondaries of the transformer bank may
one of the three windings is reversed with respect to the be reconnected in wye to increase the output voltage.
other two windings, the total voltage within the delta The voltage vectors are shown in figure 3-35, view C.
will equal twice the value of one phase; and if the delta If the phase voltage is 120 volts, the line voltage will be
is closed on itself, the resulting current will be of 1.73 x 120 = 208 volts. The line voltages are
short-circuit magnitude, resulting in damage to the represented by vectors, E1,2, E2,3, and E3,1. A
transformer windings and cores. The delta should never voltmeter test for the line voltage is represented in figure
be closed until a test is first made to determine that the 3-35, view D. If the three transformers have the same
voltage within the delta is zero or nearly zero. This may polarity, the proper connections for a wye-connected
be accomplished by using a voltmeter, fuse wire, or test secondary bank are indicated in the figure. The X1 leads
lamp. In figure 3-35, view B, when the voltmeter is are connected to forma common or neutral connection,
inserted between the X2 lead of A and the X1 lead of B, and the X2 leads of the three secondaries are brought
the delta circuit is completed through the voltmeter, and out to the line leads. If the connections of any one

Figure 3-35.—Delta-connected transformer secondaries.

3-30
 Figure 3-36.—Change connections.
winding are reverses the voltages between the three line three-phase voltage to the load. The line current is equal
wires will become unbalanced, and the loads will not to the transformer phase current in the open-delta
receive their proper magnitude of load current. In connection. In the closed-delta connection, the
addition, the phase angle between the line currents will transformer phase current
be changed, and they will no longer be 120° out of phase
with each other. Therefore, it is important to properly
connect the transformer secondaries to preserve the
symmetry of the line voltages and currents. Thus, when one transformer is removed from a
Three single-phase transformers with both primary delta-connected bank of three transformers, the
and secondary windings delta connected are shown in remaining two transformers will carry a current equal to
figure 3-36. The H1 lead of one phase is always
connected to the H2 lead of an adjacent phase, the X1
lead is connected to the X2 terminal of the This value amounts to an overload current on each
corresponding adjacent phase, and so on; and the line transformer of 1.73 times the rated current, or an
connections are made at these junctions. This overload of 73.2 percent.
arrangement is based on the assumption that the three
Thus, in an open-delta connection, the line current
transformers have the same polarity.
must be reduced so as not to exceed the rated current of
An open-delta connection results when any one of the individual transformers if they are not to be
the three transformers is removed from the overloaded. Therefore, the open-delta connection
delta-connected transformer bank without disturbing results in a reduction in system capacity. The full load
the three-wire, three-phase connections to the remaining capacity in a delta connection at unity power factor is
two transformers. These transformers will maintain the
correct voltage and phase relations on the secondary to
supply a balanced three-phase load. An open-delta
In an open-delta connection, the line current is limited
connection is shown in figure 3-37.
to the rated phase current of
The three-phase source supplies the primaries of the
two transformers, and the secondaries supply a

Figure 3-37.—Open-delta transformer connection.

3-31
and the full-load capacity of the open-delta, or
V-connected, system is

or

The ratio of the load that can be carried by two

transformers connected in open delta to the load that can
be carried by three transformers in closed delta is of the original load.
The rating of each transformer in open delta
necessary to supply the original 150-kW load is

of the closed-delta rating.

For example, a 150-kW, three-phase balanced load and two transformers require a total rating of
operating at unity power factor is supplied at 250 volts. 2 x 86.6= 173.2 kW, compared with 150 kW for three
The rating of each of three transformers in closed delta transformers in closed delta. The required increase in
is transformer capacity is

when two transformers are used in open delta to supply

and the phase current is
the same load as three 50-kW transformers in closed
delta.
Three single-phase transformers with both primary
The line current is and secondary windings wye connected are shown in
figure 3-36. Only 57.7 percent of the line voltage

If one transformer is removed from the bank, the

remaining two transformers would be overloaded.
is impressed across each winding, but full-line current
flows in each transformer winding.
To prevent overload on the remaining two transformers, Three single-phase transformers delta connected to
the line current must be reduced from 346 amperes to the primary circuit and wye connected to the secondary
200 amperes, and the total load reduced to circuit are shown in figure 3-38. This connection

Figure 3-38.—Wye-wye transformer connections.

3-32
 Figure 3-39.—Delta-wye transformer connections.

provides four-wire, three-phase service with 208 volts high-voltage, plate-supply transformers. The phase
between line wires A’B’C’ and voltage is

of the line voltage.

or 120 volts between each line wire and neutral N.
Three single-phase transformers with
The delta-connected primary, wye-connected
wye-connected primaries and delta-connected
secondary (fig. 3-39) is desirable in installations when
a large number of single-phase loads are supplied from secondaries are shown in figure 340. This arrangement
a three-phase transformer bank. The neutral, or is used for stepping down the voltage from
grounded, wire extends from the midpoint of the wye approximately 4,000 volts between line wires on the
connection, permitting the single-phase loads to be primary side to either 120 volts or 240 volts, depending
distributed evenly across the three phases. At the same upon whether the secondary windings of each
time, three-phase loads can be connected directly across transformer are connected in parallel or in series. In
the line wires. The single-phase loads have a voltage figure 3-40, the two secondaries of each transformer are
rating of 120 volts, and the three-phase loads are rated connected in parallel, and the secondary output voltage
at 208 volts. This connection is often used in is 120 volts. There is an economy in transmission with

Figure 3-40.—Wye-delta transformer connections.

3-33
the primaries in wye because the line voltage is 73 When the H1 and X1 leads are brought out on
percent higher than the phase voltage, and the line opposite corners of the transformer (fig. 3-41, view B),
current is accordingly less. Thus, the line losses are the polarity is additive. If the H1 and X2 leads are
reduced, and the efficiency of transmission is improved. connected and a reduced voltage is applied across the
H1 and H2 leads, the resultant voltage across the H2 and
X1 leads in the series circuit formed by this connection
POLARITY MARKING OF POWER will equal the sum of the voltages of the two windings.
TRANSFORMERS The voltage of the low-voltage winding aids the voltage
of the high-voltage winding and adds to it, hence the
It is essential that all transformer windings be term additive polarity.
properly connected and that you have a basic Polarity markings do not indicate the internal
understanding of the coding and the marking of voltage stress in the windings. They are useful only in
transformer leads. making external connections between transformers.

The leads of large power transformers, such as those

used for lighting and public utilities, are marked with 400-HERTZ POWER DISTRIBUTION
numbers, letters, or a combination of both. This type of In addition to the 60-hertz power supplied by the
marking is shown in figure 3-41. Terminals for the ship’s service generators, ships also have 400-hertz
high-voltage windings are marked H1, H2, H3, and so
forth. The increasing numerical subscript designates an
increasing voltage, denoting a higher voltage between
H1 and H3 than the voltage between H1 and H2.

The secondary terminals are marked X1, X2, X3,

and so forth. There are two types of markings that may
be employed on the secondaries. When the H1 and X1
leads are brought out on the same side of the transformer
(fig. 3-41, view A), the polarity is called subtractive.
The reason this arrangement is called subtractive is as
follows: If the H1 and X1 leads are connected and a
reduced voltage is applied across the H1 and H2 leads,
the resultant voltage that appears across the H2 and X2
leads in the series circuit formed by this connection will
equal the difference in the voltages of the two windings.
The voltage of the low-voltage winding opposes that of
the high-voltage winding and subtracts from it, hence
the term subtractive polarity.

Figure 3-41.—Polarity markings for large transformers. Figure 3-42.—400-hertz switchboard.

3-34
 Figure 3-43.—Bus tie connections on 400-hertz ship’s service system.

systems. On some ships 400-hertz power is generated (STC 1 thru STC 4), each rated at 150 KW at 0.8 power
by motor-generator sets and distributed via special factor (fig. 3-44) and distributed to 400 Hz loads
frequency switchboards (fig. 3-42) to the various through two distribution switchboards, designated 1SF
400-hertz equipment. and 2SF.

These motor generators supply power to ship’s Both distribution switchboards provide for
service special frequency switchboards. Figure 3-43 is centralized distribution of 450-volt, three-phase,
a simplified line diagram of the 400-hertz ship’s service 400-hertz power. Each switchboard is also capable of
bus tie interconnections on an older ship. The circuits controlling and monitoring converter input, converter
output, and bus tie circuit breakers.
being fed from the 400-hertz ship’s service
switchboards are deleted from the figure for simplicity.

Newer ships get their supply of 400-Hz power CASUALTY POWER DISTRIBUTION
SYSTEM
through the use of 60/400-Hz static converters. The
400-Hz system consists of four MBT’s supplying 60 Hz Damage to ship’s service and emergency
power to four 60/400-Hz static frequency converters distribution systems in wartime led to the development

Figure 3-44.—400Hz electric power distribution system aboard a new DDG.

3-35
of the casualty power system. This system provides the the switchboard. Then, it can be used exclusively for
means for making temporary connections to vital casualty power purposes.
circuits and equipment. The casualty power distribution
system is limited to those facilities that are necessary to RIGGING CASUALTY POWER
keep the ship afloat and permit it to get out of the danger
area. It also provides a limited amount of armament, To eliminate the necessity of handling live cables,
such as weapons systems and their directors to protect and to reduce the hazards to personnel and equipment,
the ship when in a damaged condition. there are definite procedures that must be followed and
Optimum continuity of service is ensured in ships safety precautions that must be observed in rigging
provided with ship’s service, emergency, and casualty casualty power.
power distribution systems. If one generating plant Only qualified Electrician’s Mates should do the
should fail, a remote switchboard can be connected by actual connecting; however, the portable cables maybe
the bus tie to supply power from the generator or laid out by other repair party personnel. The repair party
generators that have not failed electrician must wear rubber gloves, rubber boots, and
If a circuit or switchboard fails, the vital loads can stand on a rubber mat while making connections. Each
be transferred to an alternate feeder and source of ship’s casualty power riser or bulkhead terminal must be tested
service power by means of a transfer switch near the with a voltage tester before a connection can be made to
load that terminal. It is the duty of the repair party
Electrician’s Mate to determine that all sources of power
If both the normal and alternate sources of the ship’s to the equipment concerned are de-energized before
service power fail because of a generator, switchboard, rigging casualty power. The portable cable connections
or feeder casualty, the vital auxiliaries can be shifted to for casualty power should always be made by first
an emergency feeder that receives power from the connecting the load and then working back to the source
emergency switchboard. of power.
If the ship’s service and emergency circuits fail, On large ships, casualty power runs involve more
temporary circuits can be rigged with the casualty power than one repair party. All repair parties should rig
distribution system and used to supply power to vital simultaneously, but the rule of “rig from load to source”
auxiliaries if any of the ship’s service or emergency should always be observed. Each repair party must
generators can be operated. report its section rigged from riser or bulkhead terminal
The casualty power system includes suitable number to riser or bulkhead terminal number to damage
lengths of portable cable stowed on racks throughout the control central (DCC).
ship. Permanently installed casualty power bulkhead In all instances of rigging and energizing any part
terminals form an important part of the casualty power of the casualty power system, only the damage control
system. They are used for connecting the portable assistant, with the authority of the chief engineer, has
cables on opposite sides of bulkheads, so that power the authority to order the system energized.
may be transmitted through compartments without loss
of watertight integrity; also included are permanently In making casualty power connections at a load
installed riser terminals between decks. The vital where there are no circuit breakers or transfer switches
equipment selected to receive casualty power will have to interrupt the incoming feeder cable, the load must be
a terminal box mounted on or near the equipment or disconnected or cut at the equipment. It is quite possible
panel concerned and connected in parallel with the that the feeder cable may be damaged by the casualty
normal feeder for the equipment. that caused the loss of power. A damaged cable, if
energized, would probably trip the casualty power
Sources of supply for the casualty power system are
circuit breakers. If not disconnected, this incoming
provided at each ship’s service and emergency generator
feeder cable may be re-energized and present a hazard
switchboard. A casualty power riser terminal is
to personnel handling the casualty power cables.
installed on the back of the switchboard or switchgear
group (fig. 3-45) and connected to the busses through a To keep the phase sequence correct in ac systems,
225- or 250-ampere AQB circuit breaker. This circuit exercise care in making all connections. The riser
breaker is connected between the generator circuit terminals, bulkhead terminals, and portable cable ends
breaker and the generator disconnect links. By opening are marked to identify the A-, B-, and C-phases. You
the disconnect links, you will isolate the generator from can make the identification visually by color cede. In

3-36
 Figure 3-45.—Rear of switchboard showing casualty power terminal.

the dark you can make the identification by feeling the circuit breakers will not trip and that the cable will not
bumps on the riser terminals or feeling the twine become overheated. Current loading of casualty power
wrappings or O-rings installed on the cables. cables is not considered excessive when you can grasp
the cable by hand and it does not cause burning.
Ordinarily, portable casualty power cables should
Portable cable used in ac casualty power systems is
be tied to the overhead. High-voltage signs should be Navy LSTHOF 42. Although the normal current
attached at each connection and the information passed carrying capacity of this cable is 93 amperes, its casualty
over the ship’s 1MC system informing all hands to stand rating is 200 amperes. Under normal conditions this
clear of the casualty power cables while energized. cable will carry 200 amperes for 4 hours without
As previously stated, power panels supplying damage to the cable. Cables maybe run in parallel to
equipment designated for casualty power service will circuits that overload a single cable.
have a power terminal box mounted on the panel so that Recommended SAFE procedures to be used in
power may be fed into the panel. Remember that these rigging casualty power include the following:
panels can also be used as a source of power for the
• Upon report of loss of power, DCC orders the
casualty power system should power still be available
repair party nearest the equipment concerned to
from the permanent feeder or feeders to the panel. Some
investigate.
judgment should be exercised, however, in the choice of
panels to be used for supplying casualty power loads. • The repair party EM of the investigating team
Heavy loads should be connected to power panels immediate] y tests to determine if all sources of power
having large incoming feeders for greater assurance that to the equipment have been lost.

3-37
 • Upon determining that all power is lost, the EM 3. The EM at the switchboard opens the casualty
opens all supply switches to the equipment and reports power circuit breaker, unrigs both ends of the first
to DCC that power is lost to the equipment. portable cable, and reports “casualty power
de-energized” to main engine control. Main engine
• Upon receiving report of all power lost, DCC control reports compliance to damage control central.
requests main engine control to designate a source of
casualty power for the equipment concerned. The 4. Upon receiving the de-energized report, DCC
request for a casualty power source maybe made to the orders casualty power disconnected at the equipment.
electrical officer on ships having a combined main 5. The repair party’s EM disconnects both ends of
engine control and DCC or where the electrical officer the last portable cable in the system at the load and
is stationed in DCC for the control of generators and reports, when completed, to DCC.
power distribution.
6. DCC requests main engine control to energize
• Main engine control or the electrical officer, as normal circuits to the equipment and orders repair
appropriate, informs damage control central of the parties concerned to unrig and restow the remainder of
casualty power source to be used (giving riser terminal the portable cables.
number) and, at the same time, informs the EM on the
7. Main engine control directs the designated
appropriate switchboard that his or her board has been
switchboard to energize all normal circuits to the
designated as a source of casualty power to the riser
equipment and to report compliance. Main engine
terminal by number.
control reports compliance to DCC. The exercise is not
• Upon receiving this information, DCC orders the considered completed until DCC receives the report that
repair parties concerned to rig casualty power from the the equipment is operating on normal power and that all
equipment to the designated source. portable cables are restowed on their proper racks.

• Repair parties rig casualty power and report each Speed is desirable in all casualty power operation;
section completed to DCC. however, safety precautions must never be sacrificed to
attain speed. A thorough knowledge of the casualty
• After all sections have reported the rigging power system and frequent drills by all personnel
completed, damage control central requests the main involved are necessary for safe and expeditious results.
engine control electrical officer to “energize casualty
power.”
SHORE POWER
• Upon receiving the request to energize, main
engine control or the electrical officer directs the The number and locations of shore power
designated switchboard to “connect and energize connections vary on different types of ships. Shore
casualty power,” and to report compliance. power connections are provided at, or near, a suitable
weather-deck location to which portable cables from the
• The EM on the designated switchboard rigs the shore or from ships alongside can be connected to
first cable from the source of the system, closes the supply power for the ship’s distribution system when the
casualty power circuit breaker, reports casualty power ship’s service generators are not in operation. This
energized to main engine control, and then reports connection also can be used to supply power from the
compliance to DCC. ship’s service generators to ships alongside.

Shore-power arrangements and hardware used on

UNRIGGING CASUALTY POWER
both ship and shore installations are so diversified that
no specific installation instructions can be outlined in
Unrigging casualty power can be hazardous if not detail. Ashore installation that has one circuit breaker
handled correctly. The steps to be taken to unrig supplying a number of cable sets presents a particular
casualty power lines are as follows: hazard. In this case, you can verify phase rotation and
phase orientation only by energizing all shore terminals.
1. DCC requests main engine control to
You should check phase rotation with only one set of
de-energize the casualty power system.
cables installed. The latest designs have a single,
2. Main engine control directs the designated three-phase receptacle for ship and shore-power
switchboard to de-energize and disconnect casualty terminals. These receptacles are keyed in such a manner
power and to report compliance. that phase rotation and orientation cannot be altered,

3-38
provided both the ship and shore use these receptacles, could be damaged by a Megger test or cause a false
and the cables are not spliced. Phase orientation need reading. Test the terminals in the ship’s shore-power
not be checked prior to hookup. Systems that use terminal box or receptacle with a voltage tester to ensure
three-phase receptacles are normally designed so that that they are de-energized. Next, with a 500-volt
interlocks on receptacles automatically trip associated Megger, test the insulation resistance between terminals
circuit breakers whenever the cover of the receptacle is and from each terminal to ground.
open, and a shore-power cable plug is not in place.
However, you should still check voltage to these • Lay out the cable between the supplying
receptacles to ensure they are de-energized before shore-power outlet and the ship’s shore-power terminal
installing the shore cables. box or receptacle. Ensure that the cable is of sufficient
length to allow enough slack for the rise and fall of the
tide, but not of such length as to permit the cable to dip
RIGGING SHORE POWER
into the water or become wedged between the ship and
pier. Do not permit cables to rest on sharp or ragged
The following procedures apply to the shore
objects, such as gunwales. Avoid sharp bends. Lay
installation that has a separate circuit breaker or
cables in wood saddles or wrap them in canvas. Raise
disconnect for each set of cables and that the single,
splices and connectors from the deck or pier for
three-phase receptacle is not used You should follow
protection against water contamination. Neatly fake out
these basic instructions and procedures prior to and
excess cable to minimize damage from vehicle and
when connecting to shore power:
pedestrian movements.
• Connect and disconnect shore power under the
• Connect the shore cables to the ship’s
direct supervision of the electrical officer, a qualified
shore-power terminals according to phase or polarity
leading electrician, and shore-activity personnel.
markings in the box and on the cables.
• Visually inspect shore-power cables for any sign
• Ensure correct phase orientation (phase
of defects (such as cracks, bulges, and indications of
relationship) by checking color coding or phase
overheating), thoroughly examine spliced cables, in
identification markings on cables. Reconfirm correct
particular, because improperly spliced cables are
phase identification by meggering between like phases
extremely dangerous. Strip lug-to-lug connection
of cables. Cables that give a zero indication will have
splices of insulation and check the connection for
the same phase relationship. After meggering,
cleanliness, tightness, and good surface contact. Repair
reconnect any disconnected equipment.
all defects and reinsulate all lugs before cables are
placed in service. Check cables for insulation resistance • With a voltmeter, check to ensure that the
using a 500-volt Megger (megohmmeter). Insulation shore-power terminals are de-energized
resistance readings should meet requirements of Naval
Ships’ Technical Maunual, “Electric Plant General,” • Connect the shore-power cable to the terminals.
chapter 300. Check the resistance between phases and
• Check for proper phase rotation either by
between each phase and ground. For purposes of the
alternately energizing shore-power receptacles, one at a
test, shore ground should be the enclosure that houses
time, and observing the ship phase rotation indicator
shore-power terminals or receptacles. On ships, ground
mounted in the ship’s service switchboard, or use a
should be the hull of the ship or any metal extension of
portable meter connected to an appropriate bus. After
the hull. During the physical inspection and Megger
checking phase rotation, de-energize each source
tests, check the phase identification of the cables. Pay
shore-power receptacle before energizing the next
particular attention to cables that have been spliced to
receptacle for the phase rotation check.
ensure that the phases of the cables are continuous and
have not been altered at the splices. • Energize all source shore-power terminals or
receptacles and proceed with the transfer of electrical
• Tag with high-voltage signs and, if possible, rope
load to shore power following engineering department
off the work area surrounding the ship’s shore-power
operating instructions. Instructions will vary depending
terminal box or receptacle. This box or receptacle is
upon whether or not the ship is equipped to synchronize
often exposed to elements, and any moisture present can
with shore power.
cause a serious problem. With the ship’s shore-power
breaker tagged in the open position, disconnect all After cables are carrying the load, inspect all
equipment (such as meters and indicator lights) that connections to locate any possible overheating resulting

3-39
from poor connections or reduced copper in the circuit.
Inspect cable ends at the point of connection for heavy
strain or overheating.
Shore-power cables are rated at 400 amperes,
Check switchboard meters to ensure that the total load
on shore-power cables does not exceed the combined
rating of shore-power cables. Total shore-power load in
amperes should be no more than 400 times the number
of shore-power, three-phase cables connected per phase.

PHASE-SEQUENCE INDICATOR

A phase-sequence indicator is used when you are

connecting shore-power to your ship to ensure proper Figure 3-46.—Phase-sequence indicator.
phase relationship between ship power and shore power.
An approved type of phase-sequence indicator (fig. following safety procedures. Determine that the
3-46.) has a miniature, three-phase induction motor and shore-power busing and cables are de-energized by
three leads with insulated clips attached to the ends. using a voltage tester that has just been checked with a
Each lead is labeled A, B, and C. The miniature motor known energized power source.
can be started by a momentary contact switch. This NOTE: Moving energized shore-power cables is
switch is mounted in the insulated case with a switch prohibited.
button protruding out the front of the case to close the
switch. When the motor starts turning, you can tell its
direction of rotation through the three ports in the front SUMMARY
of the case. Clockwise rotation would indicate correct
In this chapter, the major components of an ac
phase sequence. You can stop the motor by releasing
distribution system were covered. You must remember
the momentary contact switch button.
that there are many different types of systems and
components other than the ones described in this
UNRIGGING SHORE POWER
chapter. Also, you must remember that no work on
electrical equipment should be done without using the
When you disconnect shore power, observe the
proper technical manual.
same safety precautions outlined in the connecting
sequence except for those regarding meggering cables For additional information about ac distribution
and checking phase orientation and phase rotation. systems,. refer to Naval Ship’s Technical Manual,
Again, tag shore-power breakers and disconnect chapters 300, 310, 320, and 491.

3-40
 CHAPTER 4

SHIPBOARD LIGHTING

As an Electrician’s Mate, you are responsible for LIGHTING DISTRIBUTION

maintaining the lighting distribution system aboard SYSTEMS
naval ships. This system comprises the ship’s service
The lighting distribution system in naval ships is
general lighting, and navigation and signal lights,
designed for satisfactory illumination, optimum
including searchlights.
operational economy, maximum continuity of service,
The lighting system must maintain the continuity of and the minimum vulnerability to mechanical and battle
power to selected vital lighting circuits. This is done by damage. Most ships have the following sources of
means of separate power sources and switching lighting available:
equipment that selects, in an orderly fashion, a power • A normal (ships’ service) supply from the ship’s
source suitable for proper system operation.
service bus
• An emergency (or alternate) source of power to
LEARNING OBJECTIVES supply a designated number of fixtures

Upon completion of this chapter you will be able to: • Relay-operated battery-powered hand lanterns

1. Identify the purpose of both the normal and SHIPS’ SERVICE LIGHTING
emergency lighting distribution system. DISTRIBUTION SYSTEM
2. Recognize the operation of the automatic bus
transfer (ABT) switch. The ships’ service lighting distribution system is
designed to meet the illumination needs of any activity
3. Identify the classification of lamps according to
throughout the ship. It is set up in such a manner as to
bulb shape, finish, and base.
provide a balanced load on each of the three phases
4. Identify the operating characteristics of while providing power to both the ship service lighting
incandescent and fluorescent lamps and system and the 120-volt auxiliaries. These auxiliaries
fixtures. include hotel services such as coffee makers, drinking
fountains, toasters, and small tools.
5. Identify the various navigation and signal lights
used aboard ship. It consists of feeders from the ship’s service or
emergent y power switchboards, switchgear groups, or
6. Identify the maintenance requirements for the
load centers to distribution panels or feeder distribution
various lighting fixtures in use aboard ships
points, which supply power to local lighting circuits.
today.
The lighting supply circuits are 450-volt, three-phase,
At times you will be directed to install new lighting 60-hertz, three- wire circuits supplied from the power
circuits or equipment and may find yourself without distribution system to 450/120-volt transformer banks.
installation plans or drawings. Other times you will be
correcting deficiencies found while conducting PMS EMERGENCY LIGHTING
checks, routine tests, or inspections. For these and DISTRIBUTION SYSTEM
various other reasons you should be very familiar with
the lighting system aboard your ship. Always refer to The emergency or alternate lighting distribution
the applicable blueprints, drawings, and Ship system is designed to provide a suitable distribution
Information Book, volume 3, “Power and Lighting system that, upon failure of the ships’ service lighting
Systems,” before attempting repairs on the system. system, will assure continuity of lighting in vital spaces
Additional information is found in Naval Ships’ and inboard watch stations. Continuous illumination is
Technical Manual (NSTM), chapters 300, 320, 330, 422, essential in these areas because of functional
and 583, and “Lighting on Naval Ships,” NAVSEA requirements, and when personnel are required to
0964-000-2000. remain on duty.

4-1
 The emergency or alternate system consists of The emergency/alternate switchboard is energized
selected groups of fixtures that are fed through through either the bus tie circuit breaker from the ships
automatic bus transfer (ABT) equipment. Atypical vital service switchboard or its attached emergency/alternate
lighting load is supplied from two separate switchboards generator through a generator circuit breaker. Transfer
(fig. 4-1). Normally the power is supplied from the ship between these supplies is accomplished automatically
service distribution system but, upon loss of power, is by three electrical y operated circuit breakers. The
shifted by the ABT to the emergency or alternate source circuit breakers are electrical y and mechanical] y
to keep vital lighting loads energized interlocked to prevent the closing of more than one
breaker at a time.

OPERATION If an undervoltage condition occurs while the ships

service generator(s) is/are supplying the load with an
output frequency of 57 Hz or higher, the following
Under normal conditions, the system shown in conditions will occur:
figure 4-2 operates as follows:
• circuitry in the switchboard will operate to open
1. Power is supplied from the ship service the bus tie circuit breakers in the emergency or
distribution switchboard. alternate switchboard
2. If an undervoltage condition develops on the • the emergency or alternate generator will be
ship service switchboard which is the normal
started
supply for the ABT, the ABT switch will transfer
the emergency lighting load to the alternate • when the emergency or alternate generator is up
source of power. to speed and producing 450 VAC, the generator

Figure 4-1.—Lighting distribution system.

4-2
 Figure 4-2.—Block diagram of lighting distribution system.

circuit breaker will close allowing the LIGHTING TRANSFORMERS

emergency/alternate switchboard loads to be
energized Three small single-phase transformers are used
instead of one large three-phase transformer because the
loss of a composite unit would result in a loss of power.
AUTOMATIC BUS TRANSFER
Reliability is increased by the use of three separate
(ABT) SWITCHES
transformers. If battle damage, or failure to one of the
banks of the three single-phase transformers occurs, the
ABTs are used to keep vital lighting loads energized remaining two will still carry about 58 percent of the
by shifting to the alternate power source when the initial load capacity. The remaining two transformers
normal source of power is lost. Upon restoration of will be connected open delta by disconnecting the
normal power, the ABT will automatically shift back to defective transformer. In an open delta connection, the
the normal source. Their operation is described in line current must be reduced so that it will not exceed
greater detail in chapter 3. the rated current of the individual transformers. Each

4-3
 Figure 4-3.—Delta-delta transformer connections.

transformer bank consists of three single-phase, allows the lamp to operate at higher temperatures,
delta-delta connected transformers (fig. 4-3). resulting in higher efficiency. Lamps of 50 watts or less
are of the vacuum type because inert gas would not
LIGHT SOURCES increase their luminous output.

The four sources of electric light used in naval ships The incandescent lamp is further subdivided into
are (1) incandescent, (2) fluorescent, (3) glow, and tungsten- and carbon-filament types. The
(4) low-pressure sodium lamps. tungsten-filament lamps comprise most of those listed
in this group.
A complete list of lamps used by the Navy is
contained in federal item identification number
sequence in the Illustrated Shipboard Shopping Guide
(ISSG), carried aboard all ships. ‘This list includes the
electrical characteristics, physical dimensions,
applications, ordering designation, and an outline of
each Navy-type lamp.

INCANDESCENT LAMPS

The incandescent lamp consists of a tungsten

filament supported by a glass stem (fig. 4-4). The glass
stem is mounted in a suitable base that provides the
necessary electrical connections to the filament. The
filament is enclosed in a transparent, or translucent,
glass bulb from which the air has been evacuated. The
passage of an electric current through the filament
causes it to become incandescent and to emit light.

All Navy-type 115- or 120-volt lamps (up to and

including the 50-watt sizes) are of the vacuum type and
all lamps above 50 watts are gas filled. The use of an
inert gas, which is a mixture of argon and nitrogen gases, Figure 4-4.—Components of an incandescent lamp.

4-4
Rating exposes the filament to view. These lamps are used with
reflecting equipment that completely conceals the lamps
Incandescent lamps are rated in watts, amperes, to avoid glare. Clear lamps can be used with
volts, candlepower, or lumens, depending on their type. open-bottom reflecting equipment when the units are
Generally, large lamps are rated in volts, watts, and mounted sufficiently high so that the lamps will be out
lumens. Miniature lamps are rated in amperes for a of the line of vision.
given single voltage and in candlepower for a
The inside frosted lamp consists of a glass bulb that
voltage-range rating.
has the entire inside surface coated with a frosting. The
frosting conceals the filament and diffuses the light
Classification
emitted from the lamp. These lamps can be used with or
without reflecting equipment.
Standard incandescent lamps are classified
according to their shape of the bulb, finish of the bulb, The silvered bowl lamp is provided with a glass
and type of base. globe that has a coating of mirror silver on the lower
BULB SHAPE.— The classification of lamps half. The coating shields the filament and provides a
according to the shape of the bulb with the highly efficient reflecting surface. The upper portion of
corresponding letter designation is illustrated in figure the bulb is inside frosted to eliminate shadows of the
4-5. The designation letter, which denotes the shape of fixture supports. These lamps are used with units that
the bulb, is followed by a numeral (not shown) that are designed for indirect lighting systems.
denotes the diameter of the bulb in eighths of an inch
The colored lamp may consist of a colored glass
BULB FINISH.— The clear lamp consists of a bulb bulb. These lamps are used for battle and general
that is made of unclouded or luminous glass, which lighting and for safety lights.

Figure 4-5.—Classification of lamps according to the shape of the bulb.

4-5
 Figure 4-6.—Classification of lamps according to the type of base.

BULB BASE.— The classification of lamps The classification and description of the various
according to the type of base is illustrated in figure 4-6. type of lamps and their bases is given in the following
The size of the base is indicated by name, including tables.
miniature, candelabra, intermediate, medium,
Table 4-1 gives a brief description of the types of
admedium, and mogul. They can be further classified by
lamps classified as Miniature.
application, including screw, bayonet, prefocus, and
bipin.

Table 4-1.—Description of Miniature Lamps.

4-6
 Table 4-2 gives a brief description of lamps with Table 4-4 gives a brief description of lamps with
bases classified as Candelabra. bases classified as Admedium.

Table 4-3 gives a brief description of lamps Table 4-5 gives a brief description of lamps
classified as Intermediate. classified as Medium.

Table 4-2.—Description of Candelabra Lamps.

Table 4-3.—Description of Intermediate Lamps

Table 4-4.—Description of Admedium Lamps

Table 4-5.—Description of Medium Lamps

4-7
 Table 4-6.—Description of Mogul Lamps

Table 4-6 describes lamps with bases classified as FLUORESCENT LAMPS

Mogul (fig. 4-7).
The fluorescent lamp is an electric discharge lamp
Characteristics that consists of an elongated tubular bulb with an
oxide-coated filament sealed in each end to comprise
The average life of standard incandescent lamps for
two electrodes (fig. 4-8). The bulb contains a drop of
general lighting service, when operated at rated voltage, mercury and a small amount of argon gas. The inside
is 750 hours for some sizes and 1,000 hours for others.
surface of the bulb is coated with a fluorescent phosphor.
The light output, life, and electrical characteristics of a The lamp produces invisible, short-wave (ultraviolet)
lamp are materially affected when it is operated at other
radiation by the discharge through the mercury vapor in
than the design voltage. Operating a lamp at less than
the bulb. The phosphor absorbs the invisible radiant
rated voltage will prolong the life of the lamp and
energy and reradiates it over a band of wavelengths to
decrease the light output. Conversely, operating a lamp which the eye is sensitive.
at higher than the rated voltage will shorten the life and
increase the light output. Lamps should be operated as NOTE: black dot inside a lamp symbol designates
closely as possible to their rated voltage. a gas-filled tube. (See fig. 4-8, views A and B.)

Because of their low efficiency, incandescent lamps Fluorescent lamps are now used for the majority of
are used less frequently as light sources for interior both red and white lighting on naval ships. For lighting
lighting on naval ships. fixtures that can be seen external to the ship by another

Figure 4-7.—Lamp sockets.

4-8
 Figure 4-8.—Fluorescent lamps with auxiliary equipment.

ship, yellow lighting in lieu of red is used to eliminate The use of fluorescent lamps over 20 watts has been
confusion of the red navigation lights with other red limited to special installations. For example, 60-watt
lights. Red or yellow lighting is achieved through the lamps are being used in 180-watt fixtures in hangar
use of red or yellow plastic sleeves that slide over the spaces, over workbenches in weapons repair shops, and
lamps. For 180-watt fixtures, red or yellow lighting is in dock basins on landing ship docks (LSDs).
achieved by the use of red or yellow windows. The Fluorescent lamps installed aboard ship are the
Navy has standardized three lamp sizes: hot-cathode, preheat starting type. A fluorescent lamp
1. 8 watts, used primarily in berthing spaces and equipped with a glow-switch starter is illustrated in
desk lamps figure 4-8, view A. The glow-switch starter is
essentially a glow lamp containing neon or argon gas
2. 15 watts, used chiefly as mirror lights in berthing
and two metallic electrodes. One electrode has a fixed
spaces and staterooms
contact, and the other electrode is a U-shaped, bimetal
3. 20 watts, used in one, two, or three lamp fixtures strip having a movable contact. These contacts are
throughout the ship for general lighting normally open.

4-9
 Table 4-7 describes the sequence of events in A fluorescent lamp equipped with a thermal-switch
energizing a fluorescent lamp with a glow-switch starter starter is illustrated in figure 4-8, view B (table 4-8). The
(fig. 4-8, view A). thermal-switch starter consists of two normally closed
metallic contacts and a series resistance contained in a
cylindrical enclosure. One contact is fixed, and the
Table 4-7.—Energizing a Fluorescent Lamp with a movable contact is mounted on a bimetal strip.
Glow-switch Starter
Table 4-8.—Energizing a Fluorescent Lamp with a
Thermal-switch Starter

The majority of thermal-switch starters use some

energy during normal operation of the lamp. However,
this switch ensures more positive starting by providing
an adequate preheating period and a higher induced
starting voltage.

The efficiency of the energy conversion of a

fluorescent lamp is very sensitive to changes in
temperature of the bulb; therefore, a fluorescent bulb in
a cold place will burn very dim and appear to be defective.

The efficiency decreases slowly as the temperature

is increased above normal, but also decreases very
rapidly as the temperature is decreased below normal.
Hence, the fluorescent lamp is not satisfactory for
locations in which it will be subjected to wide variations
in temperature.

Fluocrescent lamps should be operated at voltage within

±10% of their rated voltage. If the lamps are operated
at lower voltages, uncertain starting may result, and if
operated at higher voltages, the ballast may overheat.
Operation of the lamps at either lower or higher voltages
results in decreased lamp life. The performance of
fluorescent lamps depends, to a great extent, on the
characteristics of the ballast, which determines the
power delivered to the lamp for a given line voltage.

4-10
 When fluorescent lamps are operated on ac circuits, CAUTION
the light output creates cyclic pulsations as the current
passes through zero. This reduction in light output Fluorescent lamps contain mercury, which
produces a flicker that is not usually noticeable at is extremely toxic! Mercury can be swallowed,
frequencies of 50 and 60 hertz, but may cause inhaled, or absorbed through the skin. Although
unpleasant stroboscopic effects when moving objects the amount of mercury contained in each
are viewed. When using a two- or three-lamp fixture, fluorescent lamp is small, the combined
you can minimize the cyclic flicker by connecting each numbers of lamps used on board ship could
lamp to a different phase of a three-phase system (fig. impact on health and marine life if not proper] y
4-9). discarded. All used fluorescent lamps must be
turned in at the nearest defense property
The fluorescent lamp is inherently a high
disposal office, ship repair facility, or naval
power-factor device, but the ballast required to stabilize
shipyard. If a fluorescent lamp is broken, avoid
the arc is a low power-factor device. The voltage drop
breathing the mercury vapor, and be extremely
across the ballast is usually equal to the drop across the
careful in handling the broken glass to avoid
arc, and the resulting power factor for a single-lamp
cuts. Mercury spillage must be cleaned up
circuit with ballast is about 60 percent.
promptly. Detailed cleanup and disposal
Although the fluorescent lamp is basically an ac instructions are contained in NSTM, chapter
lamp, it can be operated on dc with the proper auxiliary 330, and, Mercury, Mercury Compounds, and
equipment. The current is controlled by an external Components Containing Mercury or Mercury
resistance in series with the lamp (fig. 4-8, view D). Compounds, control of, N A V S E A I N S T
Since there is no voltage peak, starting is more difficult 5100.3B.
and thermal-switch starters are required.
GLOW LAMPS
Because of the power loss in the resistance ballast
box in the dc system, the overall lumens per watt The glow lamp is a device that produces light by an
efficiency of the dc system is about 60 percent of the ac ionization process that creates the flow of electrons
system. Also, lamps operated on dc may provide as little through an inert gas such as neon or argon. This creates
as 80 percent of rated life. a visible colored glow at the negative electrode.
The majority of the difficulties encountered with Glow lamps are used as indicator or pilot lights for
fluorescent lights are caused by either worn-out or various instruments and control panels. These lamps
defective starters, or by damaged or expended lamps. have a relatively low-light output. They are used to
Lamps are considered defective when the ends are provide indication of circuit status or to indicate the
noticeably black in color. When observing the abnormal operation of electrical equipment installed in remote
operation of a fluorescent fixture, you can usually take locations. The lamp in figure 4-10 energizes when the
care of the problem by replacing either the starter or the fuse is open to draw the attention of the operator.
lamp or both.

Figure 4-9.—Fluorescent fixture three-phase connections. Figure 4-10.—Fuse holder with glow lamp.

4-11
 The glow lamp consists of two closely spaced vaporized/ionized when the lamp is operating. The
metallic electrodes sealed in a glass bulb that contains starting gas is neon with small additions of argon, xenon,
an inert gas. The color of the light emitted by the lamp or helium. Electrically the LPS ballast is similar to those
depends on the gas. Neon gas produces an mange-red used with high intensity discharge (HID) lamps. The
light, and argon gas produces a blue light. The lamp light produced by LPS lamps is different from the light
must be operated in series with a current-limiting device produced by incandescent or fluorescent lamps in that
to stabilize the discharge. This current-limiting device the color is a monochromatic yellow. All objects other
consists of a high resistance that is sometimes contained than yellow appear as various shades of gray. The
in the lamp base. characteristics of LPS lamps are as follows:
The glow lamp produces light only when the voltage • The starting time to full light output is 7 to 15
exceeds a certain striking voltage. As the voltage is minutes. If a power failure occurs and the power
decreased slightly below this value, the glow suddenly immediately is restored some lamps may return
vanishes. When the lamp is operated on alternating to full brilliance; other lamps may take the full
current, light is produced only during a portion of each starting time.
half cycle, and both electrodes are alternately
surrounded with a glow. When the lamp is operated on • The lamp, has a high efficiency that varies from
direct current, light is produced continuously, and only 131 to 183 lumens per watt.
the negative electrode is surrounded with a glow. This • The light output cannot be dimmed.
characteristic makes it possible to use the glow lamp as
an indicator of alternating current and direct current. • The fixtures cannot be converted to red or other
The glow lamp has five advantages that make it useful colors since the colors other than yellow are not
in lighting circuits: produced by the lamp.

1. It is small in size. • The lamps must be handled, stored, and disposed

of with caution.
2. It is rugged.
3. It has a long life span.
CAUTION
4. It has negligible current consumption.
5. It can be operated on standard lighting circuits.
The LPS lamps contain sodium, a highly
LOW-PRESSURE SODIUM LAMPS active chemical element, which will oxidize
rapidly and generate a high degree of heat when
Low-pressure sodium (LPS) lamps are installed exposed to small amounts of water or
aboard aircraft carriers in special applications (flight moisture-laden air. This could cause a highly
decks and hangar areas). The LPS lamp is characterized explosive hydrogen gas to be produced.
by a large diameter (2 to 3 inches), relatively long arc
tube that is double backed on itself to save space, with The amount of sodium contained in each LPS is
a two-pin, single bayonet type of base at one end (fig. small (100 to 1000 mg). The combined number of
4-11). The lamp contains small quantities of sodium lamps aboard ship could cause a potential hazard if not
which appear as silver-colored droplets that become handled, stored, or disposed of properly.

Figure 4-11.—A typical low-pressure sodium (LPS) lamp.

4-12
Handling possible, ensure lamps are stored in spaces equipped
with a sprinkling system.
You should be extremely careful in handling, using,
or replacing LPS discharge lamps. The electric Disposal
discharge lamp is designed for use in fixtures and You may dispose of the LPS lamps at sea provided
circuits wired with the proper auxiliary equipment. Do you observe the proper precautions. Break the
not scratch the glass, as the lamp is vacuum jacketed and burned-out lamps and dispose of them according to the
may explode if broken or subjected to undue pressure. manufacturer’s instructions. This means breaking a few
If the outer jacket is broken, remove and replace the lamps at a time in a dry container in a well-ventilated
lamp promptly. Avoid making contact with the arc tube area, and then filling the container with water to
supporter to prevent an electrical shock hazard. Before deactivate the sodium. Observe caution when breaking
you replace the lamp, ensure the power is secured and the lamps since the tubes may explode. Wear eye
the lamp has cooled. protection a nose mask, gloves, and adequate clothing
to protect exposed skin areas.
Storage
You should store the LPS lamps horizontally to keep LIGHT FIXTURES
the sodium evenly distributed throughout the discharge A lighting fixture, or unit, is a complete illuminat-
tube. Store the lamps in their original, individual, ing device that directs, diffuses, or modifies the light
shipping/storage containers, as they are wrapped in from a source to obtain more economical, effective, and
waxed paper or other water repellent material. If safe use of the light. Alighting fixture usually consists
breakage occurs during storage, the wrapping keeps the of a lamp, globe, reflector, refractor (baffle), housing,
sodium from contacting the corrugated paper shipping and support that is integral with the housing or any
container and possibly producing a reaction. If combination of these parts (fig. 4-12, view A). A globe

Figure 4-12.—Lighting fixtures.

4-13
alters the characteristics of the light emitted by the lamp. They are further classified according to use, such as
A clear glass globe (fig. 4-12, view B) absorbs a small
• regular permanent white-light fixtures,
percentage of the light without appreciably changing the
distribution of the light. A diffusing glass globe absorbs • regular permanent red- or yellow-fixtures,
a little more light and tends to smooth out variations in
• portable fixtures,
the spherical distribution of the light; whereas, a
colored-glass or plastic globe absorbs a high percentage • miscellaneous fixtures,
of the light emitted by the lamp. A baffle conceals the
lamp and reduces glare. A reflector intercepts the light • navigation lights, and
traveling in a direction in which it is not needed and • lights for night-flight operations.
reflects it in a direction in which it will be more useful.
Regular permanent white-light fixtures
CLASSIFICATION OF FIXTURES (incandescent, fig. 4-12, views A and B, fluorescent, fig.
4-12, views C and D) are permanently installed to
Lighting fixtures are classified according to the type provide general illumination and such detail
of enclosure provided, such as illumination as may be required in specific locations.
General illumination is based on the light intensity
• watertight,
required for the performance of routine duties. Detail
• nonwatertight, illumination is provided where the general illumination
is inadequate for the performance of specific tasks.
• pressure-proof, or Sources include berth fixtures, desk lamps, and plotting
• explosionproof. lamps.

Figure 4-13.—Weatherdeck floodlights.

4-14
 Regular red- or yellow-light fixtures (incandescent regular intervals to prevent a waste of energy and low
or fluorescent) are permanently installed to provide intensity illumination.
low-level, red or yellow illumination in berthing areas,
The loss of light caused by the accumulation of dirt,
in access routes to topside battle and watch stations, and
dust, and film on the lamps and fixtures greatly reduces
in special compartments and stations. The incandescent
the efficiency of a lighting system. The actual loss of
fixtures are equipped with steamtight, inside
light from this cause depends on the extent that oil
acid-etched, red or yellow globes.
fumes, dust, and dirt are present in the surrounding
Portable fixtures (incandescent and fluorescent) are atmosphere, and how often the fixtures are cleaned.
provided for lighting applications for which the need is When a fixture requires cleaning, turn off the light
infrequent or cannot be served by permanent y installed and remove the glassware from the lamp. Inspect
fixtures. These units are energized by means of portable internal components, wiring, and lamp holders for
cables that are plugged into outlets in the ship’s service deterioration breaks, or cracks.
wiring system and include bedside lights, deck lights,
extension lights, and floodlights. Replace them if necessary. Wash the glassware,
lamp, and reflector with soap and water. When washing
Weatherdeck lighting fixtures are provided to aluminum reflectors, avoid the use of strong alkaline
illuminate topside areas for underway replenishment and acid detergents. Rinse the washed parts with
and for flight deck operations. The fixtures are clean, fresh water that contains a few drops of ammonia
watertight and are shown in figure 4-13. Previously, red added to remove the soap film. Dry the parts with a soft
lighting was used for weatherdeck illumination cloth and replace them in the fixture.
involving replenishment-at-sea stations, and white
lighting was used for special in applications such as To replace a burned-out lamp in a watertight fixture
inport deck lights, carrier flightdeck lights, and salvage (fig. 4-14), unscrew the securing ring with a spanner
operation lights. A change was authorized by the Chief wrench, remove the globe, and replace the burned-out
of Naval Operations (CNO) to change all external lamp with a new one. Inspect the rubber gasket in the
lighting to yellow, with the exception of red navigation base and the centering gasket on the outside of the
and signal lights. This change consisted of replacing all
converters, lenses, sleeves, windows, and lamps from
red to yellow. The removed items must be retained on
board for wartime use.
Miscellaneous fixtures (incandescent or
fluorescent) are provided for detail and special lighting
applications that cannot be served by regular permanent
or regular portable lighting fixtures. These fixtures
include boom lights, crane lights, gangway lights,
portable flood lanterns, hand lanterns, and flashlights.

Navigation lights (incandescent) include all

external lights (running, signal, and anchor), except
searchlights, which are used for navigation and
signaling while underway or at anchor.

Lights for night-flight operations are used to assist

pilots (at night) when taking off and landing. These
lights also provide visual aid to pilots for locating and
identifying the parent ship.

MAINTENANCE OF FIXTURES

The lighting system should be maintained at its

maximum efficiency because artificial light has an
important bearing on the effectiveness of operation of a
naval ship. All lighting fixtures should be cleaned at Figure 4-14.—A symbol 92.2 watertight fixture.

4-15
flange. If the gaskets are worn or deteriorated, replace Preventing Collisions at Sea, 1972, (COLREGS).
them with new gaskets. Insert the globe and tighten the Statutory law requires naval compliance with the
securing ring onto the base. International Rules of the Road. However, for ships
that cannot fully comply with the regulations with
respect to number, position, arc, or range of visibility of
NAVIGATION AND SIGNAL
these lights without interfering with the special
LIGHTS
construction or function of the ship, a certification of the
Navigation and signal lights include all external closest possible compliance with the regulations issued
lights used to reduce the possibility of collision and to by SECNAV is required. The certification requests are
transmit intelligence. Figure 4-15 shows the general initiated by the Naval Sea Systems Command Figure
location of many of these lights aboard ship. 4-16 illustrates the arcs of visibility for some of the
shipboard navigation running lights.
NAVIGATION LIGHTS Presently, the U.S. Navy has two types of fixtures
in use for running lights (masthead, stern, and sick
The number, location, arc, and range of visibility of
lights) that are in compliance with the COLREGS.
the navigation lights, which must be displayed from
sunset to sunrise by all ships in international waters, are One type is the cast brass fixtures which use a
established by the International Regulations for cylindrical (open at both ends) Fresnel (corrugated) type

Figure 4-15.—General arrangement of lights for navigation.

4-16
Figure 4-16.—Arc of visibility for navigation lights.

4-17
Figure 4-17.—Navigation light fixtures, lamps, and lenses.

4-18
of lens, shown in figure 4-17, view A. The lens is
attached to the fixture base by a cap piece and four
retaining rods and nuts. The cast brass fixtures used for
side and stem lights, respectively, are shown in figure
4-17, views B and C. The brass fixture requires a
three-contact, dual-filament, mogul screw base,
incandescent lamp (fig. 4-17, view D).
Masthead and Stern Lights
The MASTHEAD and STERN LIGHTS require a
50/50-watt lamp. The sidelights require a 100/100-watt
lamp. These fixtures and lenses with the correct lamp
comply with the 1972 COLREGS and do not have to be
replaced

The second type of fixture is a newer lightweight

plastic fixture that uses a domed (open at one end) lens.
Originally these lenses were the smooth type (fig. 4-17,
view E). To comply with the 1972 COLREGS, the
Fresnel-type of lens (fig. 4-17, view F’) is required when
these fixtures are used for masthead or side lights. This
plastic fixture requires a three-contact dual-filament,
50/50-watt, medium screw base, incandescent lamp
(fig. 4-17, view H). The lamp holder of this plastic
fixture contains a spring-loaded center contact for the
primary filament, a ring contact for the secondary
filament, and a common shell contact The internal
wiring diagram of the lamp holder is shown in figure
4-18. Figure 4-18.—New navigation light fixture lamp holder wiring
diagram.
Forward and After Masthead Lights
Port and Starboard Side Lights
The FORWARD and AFTER MASTHEAD
LIGHTS (white) are spraytight fixtures provided with a
The PORT and STARBOARD SIDE LIGHTS are
50-watt two-filament lamp and equipped with an
10-point (112 1/2°) lights (fig. 4-19) located on the
external shield to show an unbroken light over an arc of
the horizon of 20 points (225°)—that is, from dead
ahead to 2 points (22.5°) abaft the beam on either side.
The forward masthead light is located on a mast or
jackstaff in the forward quarter of the vessel. The after
masthead light is located on a mast in the after part of
the vessel. The vertical separation between the
masthead lights must beat least 4.5 meters (14.75 feet),
and the horizontal separation must be at least one half
of the overall length of the vessel or 100 meters (330
feet).

NOTE: For detailed requirements of the navigation

light locations, refer to the 72 COLREGS requirements,
which are printed in the U.S. Coast Guard publication
COMMANDANT, INSTRUCTION M16672.2A and
Code of Federal Regulations, CFR 33-81.20. The U.S.
Navy’s certifications of closest possible compliance is
summarized in CFR 32-706. The U.S. Navy’s special
lights are covered in CFR 32-707. Figure 4-19.—Side light fixture.

4-19
respective sides of the vessel, showing red to port and conjunction with the ship’s task lights when both are
green to stardoard. The fixtures are spraytight, each installed.
provided with a 50-watt, two-filament lamp, and
equipped with an external shield arranged to show the Constrained by Draft
light from dead ahead to 2 points abaft the beam on the Lights
respective sides. On older vessels, these fixtures may
be 100-watt brass fixtures.
The CONSTRAINED BY DRAFT LIGHTS (red)
are a dual array of three 32-point (360°) lights. This
Stern Light
light array is similar to a task light array except that the
middle light fixtures are equipped with dual-color
The STERN LIGHT (white) is a 12-point (135°)
(red/white) lenses. (See fig. 4-23, view C.) This middle
light located on the stem of the vessel. It is a watertight
fixture provided with a 50-watt filament lamp and fixture is spraytight and equipped with a multiple socket
equipped with an external shield to show an unbroken (fig. 4-23, view D) provided with nine 15-watt,
light over an arc of the horizon of 12 points of the one-filament lamps. Six lamps are used in the top
compass-that is, from dead astern to 6 points on each multiple bulb socket for the red light and three in the
side of the ship. bottom socket for the white light. Each light is
energized from separate circuits. The middle red lights
Forward Towing Lights are used in conjunction with the top red lights and
bottom red lights for constrained-by-draft light
FORWARD TOWING LIGHTS (white) and functions, while the middle white lights are used
AFTER TOWING LIGHTS (yellow) are normally with these lights for task light functions. The dual,
for ships engaged in towing operations. The forward three red light array is displayed simultaneously to
upper and lower towing lights are 20-point (225°) indicate the ship is unable to get out of the way of an
lights, identical to the previously described masthead approaching vessel in a narrow channel, due to
lights. These lights are installed on the same mast ship’s deep draft. The switch for this light display is
with the forward towing operations. The forward upper labeled SHIP’S CONSTRAINED BY DRAFT
and lower towing lights are 20-point (225°) lights,
LIGHTS.
identical to the previously described masthead lights.
These lights are installed on the same mast with the
forward or after masthead lights, and the vertical Clearance/Obstruction
separation is 2 meters (6.6 feet). The after towing light Lights
is a 12-point (135°) light, similar to the previously
described stern light except for its yellow lens. It is The CLEARANCE/OBSTRUCTION LIGHTS
installed 2 meters (6.6 feet) directly above the white (red/green) are a dual array of two 32-point (360°)
stem light. lights. The fixtures are identical to the middle
constrained-by-draft light (fig. 4-23, view C) except
Breakdown and Man Overboard that the lens of the lower half of the fixture is green.
Lights This array is placed port and starboard on the ship,
two fixtures in a vertical line, not less than 2 meters
The dual-array BREAKDOWN and MAN (6.6 feet) apart at a horizontal distance of not less
OVERBOARD LIGHTS (red) are 32-point (360°) than 2 meters (6.6 feet) from the task lights in the
lights located 2 meters (6.6 feet) apart or (vertically) athwartship direction (fig. 4-15). Each upper and lower
and mounted on brackets on port and starboard of
half of the fixture in the array is energized from separate
the mast or structure. This arrangement permits
circuits. This dual-light array is used by a ship engaged
visibility, as far as practicable, throughout 360° of
azimuth. The fixtures are spraytight and equipped in dredging or underwater operations, such as salvage,
with six 15-watt one-filament lamps. When these to indicate her ability to maneuver is restricted. The
lights are used as a man-overboard signal, they are two red lights in a vertical line indicate the side on which
pulsed by a rotary snap switch (fitted with a crank the obstruction exists, and the two green lights in a
handle) on the signal and anchor light supply and control vertical line indicate the side on which another ship may
panel. These lights are mounted and operated in pass.

4-20
Minesweeping Lights used on some ships). The anchor lights are energized
through individual on-off rotary snap switches on the
The MINESWEEPING LIGHTS (green) are an signal and anchor light supply and control panel in the
array of three 32-point (360°) lights placed to form a pilot house. The after anchor light is placed at least 4.5
triangular shape. These fixtures are equipped with meters (14.75 feet) lower than the forward anchor light
50-watt lamps. One of the lights is placed near the
(table 4-9).
foremast head and one at each end of the fore yardarm
(fig. 4-15). These lights indicate that it is dangerous for
another ship to approach within 1000 meters (3280.8 Testing Navigation Lights
feet) of the mine-clearance vessel.
The supply, control, and telltale panel for the
Ship’s Task Lights running lights is a nonwatertight, sheet metal cabinet
designed for bulkhead mounting. ‘This panel (fig. 4-20)
The SHIP’S TASK LIGHTS are a dual array of
is provided to aid a ship in keeping its running lights lit
three 32-point (360°) lights, port and starboard of the
mast or superstructure. They are arranged in a as prescribed by the rules for preventing collisions at
vertical line, one pair over the other so that the upper sea. It is installed in or near the pilot house and gives
and lower light pairs are the same distance from, and an alarm when one of the navigation lights (forward and
not less than 2 meters (6.6 feet) above or below, the after masthead, stem, and side lights) has a failure of its
middle light pairs. The lights must be visible for a primary filament and is operating on its secondary
distance of at least 3 miles. The upper and lower lights filament.
of this array are red, and the center lights are a clear
white. All shipboard navigational lights are tested daily
while at sea. The test is usually made 1 hour before
These lights are equipped with multiple 15-watt,
one-filament lamps and are connected to the navigation sunset by the Quartermaster. The following paragraphs
light supply and control (not the telltale) panel. They describe the indicated warnings of the telltale panel
may be controlled as follows: when a malfunction occurs.

• The upper and lower red lights may be burned 1. Failure of the primary filament/circuit of any
steadily to indicate the ship is not under one of the lights (forward and after masthead,
command. stem, or side lights), will de-energize a relay
• The upper and lower red lights may be flashed 2. This relay
by rotating the switch crank handle on the supply
a. effects a transfer of power to the secondary
and control panel to indicate a man-overboard
filament of the affected light,
condition exists.
b. sounds a buzzer
• The three lights may burn simultaneously
to indicate the ship is unable to get out of the c. lights an indicator light, and
way of approaching vessels. (This may be d. moves an annunciator target to read OUT
due to launching or recovering aircraft,
(reads RESET when de-energized).
replenishment-at-sea operations, and so forth)
The switch for this application is labeled SHIP’S To silence the buzzer, you turn the handle of the
TASK LIGHTS. reset switch 90° to the horizontal position. However,
the indicator lamp of the affected light stays lit until the
Forward and After Anchor repair has been completed, and the reset switch is turned
Lights back to the normal (RESET) position. Certain ships
have permanent towing lights installed and connected
The FORWARD and AFTER ANCHOR LIGHTS
(white) are 32-point (360°) lights. The forward anchor to control switches in the telltale panel. The towing light
light is located near the stem of the ship, and the after switches are manual. When failure of the primary
anchor light is at the top of the flagstaff. The fixtures filament occurs in towing lights connectedto this panel,
are splashproof, each provided with a 50-watt, the switch must be manually turned to the position
one-filament lamp (50/50-watt, dual-filament lamps are marked SEC, to energize the secondary filament.

4-21
Figure 4-9.—Summary of Navigation Lights

4-22
Figure 4-20.—Supply, control, and telltale panel, symbol 969.1.

4-23
Sequence of Operations 3. The annunciator target still reads OUT.
When the defective lamp is replaced (or the fault in
The operations of the supply control and telltale
the primary circuit is corrected), the following events
panel are easily seen by following the schematic
occur:
diagram in figure 4-21. For simplification this
schematic shows only one of the five running lights; the 1. The relay coil is energized and relay contacts X
operation is the same for all five. and Y are opened.
When the primary filament of a running light is 2. The annunciator coil is then de-energized,
lighted, relay contacts X, Y, and Z are open; the indicator opening contact Z.
lamps, annunciator, and buzzer are not energized. The
3. The target indicates RESET. The secondary
reset switch must be kept pointing in the RESET
filament is now de-energized, and the indicator
(vertical) position under normal conditions, or the
lamps are lit.
buzzer will not be energized when a failure occurs.
If the primary filament circuit is opened or the 4. The reset switch is returned to the RESET
filament burns out, the following events will occur: (vertical) position.

1. The relay is de-energized, causing contacts X 5. The indicator lamps go out.

and Y to close. 6. The entire unit is again operating in the normal
2. Then the secondary filament and the indicator condition.
lamps are lighted, and the annunciator target A dimmer control panel connected as shown in
drops to the OUT position, closing contact Z, figure 4-22 is provided for dimming the running lights.
and the buzzer sounds. This panel provides only one dimming position. In the
When the RESET switch handle is turned to the dim position the visibility of the mastheads, side lights,
horizontal position, the following events will occur: and the stern light is reduced considerably. The
sequence of operation of the telltale panel is the same
1. The buzzer is silenced.
whether the running lights are in the bright or dimmed
2. The indicator lamps remain lighted. condition.

Figure 4-21.—Running light, supply, control, and telltale panel schematic diagram.

4-24
 Figure 4-22.—Dimmer control panel, symbol 989.

NOTE: Navigation lights do not conform to the is installed near the stem on ships that are engaged in
rules of the road when they are in the dim position; convoy operations and mounted to show an unbroken
therefore, they are dimmed ONLY when directed by arc of light from dead astern to 6 points on each side of
higher authority. the ship.

SIGNAL LIGHTS (OPERATIONAL

Wake Light
OR STATION)

Task lights are used to indicate the ship is in a The WAKE LIGHT (white) is installed on the
restricted maneuverability status (replenishment at-sea flagstaff or after part of the ship to illuminate the wake
or aircraft operations). Hull contour lights are required and is mounted so that no part of the ship is illuminated.
to indicate the contour of the ship. Station marker lights The fixture is spraytight and of tubular construction.
are used on ships, capable of delivery, to mark the One end of the fixture is fitted with an internal screen,
replenishment station location. having a 1 1/4-inch diameter hole provided with a lens
(1 13/16-inch diameter x 3/16-inch thick) through
Stern Light
which light is emitted from a 50-watt lamp (T-12
The STERN LIGHT (blue) is a 12point (135°) light, tubular). A suitable mounting bracket is included for
similar to the previously described white stem light. It adjusting the position of the light, thereby illuminating
is a watertight fixture provided with a 50-watt lamp and the ship’s wake.

4-25
Aircraft Warning Lights participate in ASW operations. The light is positioned
on either the yardarm or mast platform where it can best
The AIRCRAFT WARNING LIGHTS (red) are be seen all around the horizon. Two red, two green, and
32-point (360°) lights (fig. 4-23, view A) installed at or two amber lenses are provided with each fixture. The
near the top of each mast. If the light cannot be located colors used are determined by operating forces.
so that it is visible from any location throughout 360° of
azimuth, two aircraft warning lights (one on each side Station Marker Box Signal Light
of the mast) are installed However, a separate aircraft
warning light is not required if a 32-point red light is The STATION MARKER BOX SIGNAL LIGHT
installed at the truck of a nearby mast for another
(fig. 4-24) has nine holes, each fitted with a red lens.
purpose. The fixtures are spraytight and equipped with The hand-operated individual shutters hinge upward.
multiple sockets provided with 15-watt, one-filament Illumination is by two 25-watt bulbs; one is a standby
lamps (fig. 4-23, view B). bulb.

Revolving Beam ASW (Grimes) Light One watertight receptacle is installed at each
replenishment-at-sea station, outboard near or under the
The REVOLVING BEAM ASW (GRIMES) rail or lifeline. On some underway-replenishment ships,
LIGHT is displayed for intership signaling during ASW the boxes are permanently mounted The lights have no
operations and is installed on all ships equipped to special arcs-of visibility requirements.

Figure 4-23.—Constrained by draft and/or task light fixtures.

4-26
 water, fuel oil, and ammunition, are to be sent to certain
stations. When the marker box is flagged correctly,
there will be little chance of receiving the wrong cargo
at a station.
The Boatswain’s Mates will usually test the station
marker box prior to underway replenishment, but you
should be prepared for any possible trouble and have
spare light bulbs readily available.

Hull Contour Lights

The HULL CONTOUR LIGHTS (blue) are found

on replenishment-at-sea delivery ships. These lights
assist the receiving ship coming alongside during
replenishment operations by establishing the delivery
ship’s contour lines. Two or three hull contour (blue)
signal lights (135°arc) are located on each side of the
delivery ship (fig. 4-25) at the railing. Additional lights
may be installed if obstructions exist beyond the
delivery ship’s parallel contour lines.

SIGNAL LIGHTS VISUAL

Figure 4-24.—Station marker box, symbol 285.
COMMUNICATIONS

Station marking boxes are used for visual

communications between the replenishment-at sea The signal lights for visual communications include
stations of the sending and the receiving ships. Specific the blinker lights located on the yardarm, multipurpose
combinations of lights indicate that stores, such as signal lights, and searchlights.

Figure 4-25.—Replensihment at sea lighting.

4-27
Blinker Lights one-filament lamps and fitted with a screen at the base
to prevent glare or reflection that may interfere with the
navigation of the ship. These lights are operated from
The BLINKER LIGHTS (white) are 32-point
signal keys located on each side of the signal bridge.
(360°) lights (fig. 4-26) located outboard on the signal
yardarm, one port and one starboard. The fixtures are Older blinker units (fig. 4-26, view A) have a cluster
spray tight, each provided with multiple 15-watt, of six 15-watt lamps in a single multiple-lamp socket,

Figure 4-26.—Blinker light fixture.

4-28
similarly arranged as in the warning light (fig. 4-23, communications. The light is designed to operate from
view B). Newer units are shown in figure 4-26, view B. an internal battery or from the ship’s service power
These newer units have two clusters of six lamps. supply using a 120/20-volt transformer mounted in the
Cluster No. 1 maybe used only for normal use. Cluster carrying case. In the signaling operation, an adjustable
No. 2 maybe added by switching to increase brilliance front handle assures a steady position. Front and rear
for communication at greater distance. Cluster No. 2
sights are provided to direct the beam on the desired
may be selected alone when No. 1 fails.
target.

Multipurpose Signal Light Supplied with the light, in addition to the stowage
box, are red, green, and yellow lenses, a 15-foot power
The portable multipurpose signal light (fig. 4-27) cable for supplying power from the ship’s ac source to
produces a high-intensity beam of light suitable for use the stowage box, a 25-foot cable for supplying power
as a spot light or as a blinker light. A trigger from the stowage box to the light, and the
switch located on the rear handle is used for manufacturer’s technical manual.

Figure 4-27.—Multipurpose signal light, symbol 106.1.

4-29
Searchlights withstand high vibratory shock and extreme humidity
conditions and operates equally well in hot or cold
Naval searchlights are used to project a narrow climates.
beam of light for the illumination of distant objects and his searchlight may be furnished for operation
for visual signaling. To accomplish its purposes, the either with a 60-hertz, 115-volt transformer to step the
searchlight must have an intense, concentrated source voltage down to 28 volts or without a transformer to
of light, a reflector that collects light from the source (to operate on 115 volts using the proper rated sealed-beam
direct it in a narrow beam), and a signal shutter (to unit. The same unit is available for use on small craft
interrupt the beam of light). from a 28-volt power source.

Searchlights are classified according to the size of The searchlight has four main parts:
the reflector and the light source. The three general
classes are the 8-inch, 12-inch and 24-inch searchlights. 1. The base, which is equiped with a rail clamp
The 8-inch searchlight is of the sealed-beam for securing the searchlight to the rail.
incandescent type. The 12-inch light are of the
2. The yoke, which is swivel mounted on the base
incandescent and mercury-xenon type. The 24-inch
to allow it to be trained through 360°.
carbon-arc searchlight is not addressed in this manual.
Refer to Naval Ship’s Technical Manual, chapter 422, 3. The housing, which provides an enclosure for
for information on this light the lamp and is composed of a front and a rear
section.
8-INCH SEALED-BEAM SEARCHLIGHT.—
The 8-inch signaling searchlight (fig. 4-28) uses an 4. The lamp, which provides the source of light.
incandescent sealed-beam lamp. It is designed to The front section of the housing comprises the
shutter housing, and the rear section comprises the
backshell housing, containing a 115/28-volt step-down
transformer. The two sections are held together by a
quick-release clamp ring that permits easy replacement
of the lamp. The backshell and lamp assembly, when
detached, may be used as a portable searchlight. The
entire housing is mounted on brackets attached to the
shutter housing and supported by the yoke to allow the
searchlight to be elevated or depressed. Clamps are
provided for securing the searchlight in train and
elevation.

The shutter housing contains the venetian blind

shutter, which is held closed by springs and manually
opened by a lever on either side of the housing. The
front of the shutter housing is sealed by the cover glass
and a gasket. The rear of the shutter housing is
enclosed by a gasket and adapter assembly. The adapter
assembly provides a locating seat for the lamp and
incorporates a hook and key arrangement that aligns the
backshell housing and retains it in position while
attaching the clamp ring to hold the two sections
together.

Three filter assemblies (red, green, and yellow) are

provided and can be readily snapped in place over the
face of the searchlight. The shutter vanes can be locked
in the open position for use as a spotlight.

Figure 4-28.—An 8-inch, 60-hertz, sealed-beam searchlight. To remove the lamp from the housing for cleaning
or replacement, use the following procedure:

4-30
 1. Tip the rear end of the searchlight up to its The signaling shutter is a venetian blind shutter
highest position and lock it in place. mounted inside the drum behind the front door. It is held
in the closed position by two springs and is manually
2. Release the clamp ring toggle and remove the
opened by a lever on either side of the drum. The
clamp ring (fig. 4-27).
parabolic metal reflectors mounted on the inside of the
3. Remove the backshell assembly by raising it up. rear door.
This will disengage it from the hook and tab.
The lamp is usually a 1,000-watt, 117-volt
4. Pull the gasketed lamp out of the shutter adapter
incandescent lamp having special concentrated
assembly by gripping the lamp gasket on its
filaments that reduce the area of the light beam. The
periphery and lifting it out. This will disengage
lamp is mounted in a mogul bipost socket. The socket
the gasket lugs from the notches in the adapter
assembly. is located in front of the reflector and can be adjusted
only slightly. The replacement of the lamp is
To replace the lamp in the housing, take the accomplished through the rear door of the search-
following actions:
light.
1. Make sure that the word TOP marked on the
12-INCH MERCURY-XENON SEARCH-
lamp is aligned with the word TOPon the gasket
LIGHTS.— Some of the older mercury-xenon
and that the lugs of the lamp are firmly seated in
searchlights are 12-inch incandescent lamp searchlights
the recesses provided in the gasket.
converted to use a 1,000-watt compact mercury-xenon
2. Make sure that the lugs are set into the notches arc lamp. The addition of a small amount of mercury to
in the adapter assembly located inside, and at the the xenon gas produces a much more brilliant light with
rear of, the shutter housing.
a great deal of radiation in the green and ultraviolet parts
3. Set the backshell assembly over the shutter of the spectrum. The increases in light intensity greatly
assembly, engaging the shutter hook into the slot increase the range of the searchlight.
of the backshell.
The modifications needed to convert the
4. Using the hook as a hinge, carefully swing the incandescent lamp searchlights include installation
lower part of the backshell down to the shutter of a lamp holder, lamp adjuster assembly, and lamp
assembly, engaging the shutter tab into the notch
in the rolled edge of the backshell. Be careful to
swing the backshell down in a straight line to
make direct engagement and to ensure proper
positioning of the lamp contacts on the terminals
of the lamp.
5. Replace the clamp ring, making sure that the
hinge pin is set into the notches of the adapter
and backshell assemblies.
12-INCH INCANDESCENT SEARCH-
LIGHT.— The 12-inch incandescent searchlight is
used primarily for signaling and secondarily for
illumination.
The searchlight (fig. 4-29) is comprised of the
mounting bracket, yoke, drum, and lamp. The mounting
bracket permits the searchlight to be secured to a vertical
pipe or to a flat vertical surface. The yoke is swivel
mounted on the bracket to allow the searchlight to be
rotated continuously in train. The steel drum provides
a housing for the lamp, and its trunnion is mounted on
the yoke so that it may be elevated or lowered Clamps
are provided for locking the searchlight in any position Figure 4-29.—A 12-inch incandescent searchlight.
of train elevation.

4-31
starter assembly mounted on the searchlight drum The wiring diagram for the early model 12-inch
(fig. 4-30). mercury-xenon arc searchlight is shown in figure 4-31.
Other modifications include the following:

• Providing a 115-volt, 60-hertz ballast unit WARNING

mounted below deck near the searchlight,
connected by a flexible cable Do not bridge or depress the safety switch
when working on the assembly or when
• Installing the short-arc mercury-xenon arc lamp replacing the lamp. Opening the searchlight
drum opens all contacts of the safety switch,
• Furnishing the additional onboard repair parts
protecting personnel against electric shock. As
necessitated by the changes, which include a an additional safety precaution, disconnect the
ballast, transformers, capacitors, spark gap, and plug on the starter box before opening the door.
switch circuit.

Figure 4-30.—A 12-inch incandescent searchlight converted to use a mercury-xenon arc lamp.

4-32
 Figure 4-31.—Wiring diagram for an early model 12-inch mercury-xenon arc searchlight.

Starting Circuit.— The secondary of the step-up Operating Circuit.— The operating circuit
transformer in the starting circuit supplies high voltage includes four ballast resistors, which permit the lamp to
to a radio-frequency circuit consisting of a spark gap, operate at 25 volts during warmup after the arc has been
capacitors, and the three-turn primary of the pulse struck and up to 65 volts at full lamp output. A fifth
transformer. The secondary of the pulse transformer resistor is automatically connected during starting and
produces a momentary high voltage for starting the removed after the arc is struck
arc.
Safety Switch.—The safety switch has three
When the arc starts, the secondary of the pulse contacts, S-3, S-4, and S-6. The actuating lever of this
transformer is short-circuited and the lamp is now switch projects a short distance into the searchlight drum
energized on line voltage reduced by the drop in the from the top of the starter assembly. It is mechanically
ballast. linked to the reflector or the shutter housing, depending

4-33
on which is hinged, to provide access for relamping or • Keep all electrical contacts clean and bright.
cleaning.
• Check electrical leads daily an replace them as
XENON AND MERCURY-XENON ARC soon as defects appear.
LAMPS.— Mercuty-xenon gas-filled arc lamps operate
• Lubricate trunnion bearings and stanchion
on 60-hertz alternating current or, with some change in
the starter circuit and ballast resistor, on 400-hertz sockets according to PMS requirements.
alternating current. The light produces a concentrated Adjust the two shutter stop screws, located next to
arc of intense brilliance, which provides sharp focusing. the handles to compensate for wear in the leather
Searchlights with mercury-xenon arc lamps are bumpers. These bumpers cushion the shock of the
normally used for signaling, but they may also be used shutter vanes closing. The bumpers should just touch
for illumination. The 12-inch mercury-xenon arc
the stop adjustment when the vanes are closed to prevent
searchlight includes the following parts:
the shaft from twisting. Check the shutter vanes
1. 1,000-watt lamp frequently to ensure that all screws are tight.
2. Drum Clean the reflector weekly or more often to remove
3. Back dome dust. Remove salt spray from the lens and reflector as
necessary. You should use the following instructions to
4. Signaling shutter
clean the reflector:
5. Mounting yoke
• Ensure that the surface is cool. Touching a hot
6. Focusing device
surface with your bare skin can result in a serious
7. Automatic lamp starting circuit (attached to the burn.
lower part of the drum)
• Use standard Navy brightwork polish.
8. Screening hood with various colored falters
• Use a soft, lint-free cloth, or clean the reflector
The wiring diagram of the 12-inch mercury-xenon
in accordance with the PMS MRC.
arc searchlight is shown in figure 4-32.
• Use a radial motion from the center to the rim of
Automatic Starting Circuit.— A high-voltage
pulse type of circuit is used When the searchlight is the reflector. Do not use a circular motion.
turned on, the booster transformer supplies 130 volts to • Do not paint bolts, locking nuts, and other parts
the primary of the transformer, which in turn provides a necessary for access to the interior or over
series of pulses of about 50,000 volts generated by nameplate data. Keep oiling holes free of
high-frequency discharges through a spark gap.
paint.
When the main arc in the lamp is established, the Only qualified Electrician’s Mates should replace
voltage in the primary of the transformer drops to 65
the lamp or adjust the focusing unless a member of the
volts. This voltage is not high enough to cause the
signal gang is qualified. The light source must be at the
secondary voltage of the transformer to break down the
focusing point of the reflector for minimum beam
spark gap. Thus, the high-voltage pulses to the lamp
spread and maximum intensity. Some types of 12-inch
automatically y stop.
incandescent searchlights are provided with focusing
Ballast Circuit.— Five parallel-connected resistors adjustment screws. Other types can be adjusted by
are connected in series with the lamp as shown in figure loosening the screws that hold the lamp-socket support
4-32. These resistors limit the current at starting and plate in position. The entire socket assembly can be
during operation, supplying the correct electrical values moved toward or away from the reflector until the
to the lamp. beam has a minimum diameter at a distance of 100
MAINTENANCE ON 8- AND 12-INCH feet or more from the light. The screws must be
SEARCHLIGHTS.— These searchlights are main- retightened after the final adjustment. The diameter of
tained by following the same practice that relates to all the beam must be checked with the rear door clamped
electrical and mechanical equipment: tightly shut.

4-34
 Figure 4-32.—Wiring diagram for a 12-inch mercury-xenon arc searchlight.

A screen hood is provided for attachment to the front location of the ship. Darkened ship condition is
door to limit the candlepower of the beam, to cut down achieved by the following means:
its range, and to reduce stray light, which causes
1. Light traps that prevent the escape of light from
secondary illumination around the mainbeam; the hood
illuminated spaces
also allows for the use of colored filters.
2. Door switches that automatic-ally de-energize
the lights when the doors are opened
DIVERSIFIED LIGHTING
EQUIPMENT When darkened-ship condition is ordered, check
every door switch installation aboard ship to determine
Diversified lighting equipment restricts the that all lock devices or short circuiting switches are set
visibility of light and reduces the amount of glare or in the DARKENED SHIP position.
background illumination. This equipment includes
lights for darkened-ship condition and special lights for Inspect the light traps to determine that they are free
various uses. of all obstructions. A light-colored object of any
appreciable size placed in a light trap might be
DARKEN SHIP EQUIPMENT sufficiently illuminated by the interior lighting to be
visible beyond the safe limit. Note the positions of the
Darkened ship is a security condition designed to hand lanterns when entering a compartment so that you
prevent the exposure of light, which could reveal the can find them without delay when they are needed.

4-35
Light Trap Door Switch

A door switch is mounted on the break side of a door

Alight trap (fig. 4-33) is an arrangement of screens jamb (inside the compartment) and operated by a stud
placed inside access doors or hatches to prevent the welded to the door. When the door is opened, the switch
escape of direct or reflected light from within. The is automatically opened at the same time. Door switches
inside surfaces of the screens are painted fiat black so are connected in a variety of ways to suit the
that they will reflect a minimum of light falling on them. arrangement of each compartment.
Light traps that are used to prevent the escape of white
light should have at least two black, light-absorbing All door-switch installations are provided with
surfaces between the light source and the outboard lock-in devices or short-circuiting switches to change
openings. Light traps are preferred to door switches in the settings of the door switches, as required from
locations when the following conditions exist: lighted ship to darkened ship and vice versa. Each
standard door switch is furnished with a mechanical
1. Egress or ingress is frequent lock-in device for use when only one door switch is
installed. When two or more door switches are
2. Interruption of light would cause work stoppage
connected in series, a single, separately mounted
in large areas
short-circuiting switch is installed in an accessible
3. Light might be exposed from a series of hatches, location to avoid the possibility of overlooking any of
one above the other on successive deck levels the door switches when the changeover is made from
lighted ship to darkened ship and vice versa.
4. Many small compartments and passages are
joined by numerous inside and outside doors that When a single door switch at an outer door is
would complicate a door-switch installation connected in parallel with door switches at inner doors,

Figure 4-33.—Light trap.

4-36
only the door switch at the outer door is provided with SPECIAL LIGHTS
a lock-in device, and the lock-in devices are removed
from the other outer doors. The location of the control
Special lights are provided aboard ships for various
switch is indicated by a plate mounted adjacent to each uses. These lights include flashlights, floodlights, hand
door switch. The control switch is marked lanterns, and flood lanterns (fig. 4-34). Lights and
CAUTION-DOOR SWITCH CONTROL. The portion lighting fixtures are identified by NAVSHIPS symbol
of the short-circuiting switch that connects the door numbers (1 through 399), military standard (MS)
switches in the circuit is marked DARKENED SHIP, numbers, national stock numbers (NSN), military
and the portion that disconnects the door switches from specification numbers, or NAVSHIPS drawing
the circuit is marked LIGHTED SHIP. Personnel numbers. The NAVSHIPS Standard Electrical Symbol
should become familiar with the location of the List (NAVSEA S0300-AT-GTP-010/ESL, formerly
short-circuiting switch in all compartments, and the NAVSEA 0960-000-4000) lists the lights and lighting
number of doors that it controls. fixtures in current use on naval ships. Fixtures are listed

Figure 4-34.—Special lights.

4-37
in NAVSEA symbil number order along with the MS or top of the lantern case (fig. 4-34, view D). The 115-volt
NAVSHIPS drawing number, and NSN. ac version is identified by symbol 101.2. Symbol 102.2
identifies the 115-volt dc type. A three-conductor cable
Floodlights (including a green conductor to ground the relay metal
frame) is provided for the connection to a lighting
The white floodlight (fig. 4-34, view A), symbol circuit. THE RELAY-CONTROLLED LANTERN
300.2, consists of a splashproof housing equipped with MUST ALWAYS BE INSTALLED WITH THE
a rain-shielded hinged door secured with a latch. The RELAY UPRIGHT. This specific arrangement of the
300-watt lamp is a sealed-beam type. The lamp housing relay prevents a fire hazard, caused by a chemical action
is trunnioned on a yoke, which in turn is mounted on a of the electrolytic paste leaking from the battery case to
shock-absorbing base. The light is held in elevation by the relay housing as the battery is being discharged
a clamp on the yoke. Train positioning is accomplished (operated).
by friction within the shock-absorbing base. Each
Relay-controlled lanterns are installed in spaces
floodlight is furnished with a three-conductor cable
where continuous illumination is necessary.
(including a green lead to ground the metal housing) for
connecting into a lighting circuit. These spaces include essential watch stations,
Floodlights with 300 watts (symbols 263 and 303), control rooms, machinery spaces and battle dressing
150 watts (symbol 317), and 200 watts (symbol 69) are stations. The lanterns must illuminate the tops and
also used. Floodlights are installed on weather decks at bottoms of all ladders and all flush-mounted scuttles.
suitable locations to provide sufficient illumination for They must also be mounted to illuminate all gauges at
the operation of cranes and hoists, and the handling of vital watch stations. Operating personnel will depend
boats. on these lanterns for illumination when bringing
machinery back on the line after a casualty. These
Hand Lanterns lanterns must not be installed in magazine or
powder-handling spaces where fixed or semi-fixed
Two types of dry battery powered lanterns are ammunition is handled, or in any location where
available for installation in certain strategic locations to explosion-proof equipment is installed.
prevent total darkness if all lighting fails. One type is
hand operated, while the other is operated automatically The lantern relay is connected in the lighting circuit
by a relay when power to the lighting distribution system (in the space in which the lantern is installed) on the
fails. power supply side of the local light switch that controls
the lighting in the space concerned. Thus, the relay
The manually operated portable lantern (fig. 4-34, operates and causes the lamp in the lantern to be
view B), consists of a watertight plastic case containing energized from its batteries only when a power failure
two 6-volt batteries connected in parallel. It includes a occurs, not when the lighting circuit is de-energized by
sealed-beam lamp, rated at 5 volts, but operated at 6 the light switch. If the space is supplied with both
volts (when the batteries are new) to increase the light emergency and ship’s service lights, the lantern relay is
output. A rigid handle is secured to the top of the case. connected to the emergency lighting circuit only.
The lantern is operated by a toggle switch with the lever
positioned near the thumb for ease of operation. When The lantern relay should be fused so that a short
the batteries are new, the lantern can be used circuit in the relay leads of one compartment will be
continuously for about 8 hours before the light output cleared through low-capacity fuses before the fault
ceases to be useful. causes heavier fuses nearer the source of power to blow
and cut off the power supply to lighting circuits in other
Manually operated lanterns are installed as an
compartments. The fuses that protect the branch
emergency source of illumination in spaces that are
circuits are ample protection for the lantern relay. A
manned only occasionally. These lanterns are also used
lantern relay can be connected directly to the load side
in certain areas to supplement the relay-operated
of the fixes in fuse boxes or switchboxes. If a relay
lanterns. You should not remove manual] y operated
cannot be connected to a branch circuit, it can be
portable lanterns from their compartments unless the
connected to the source side of a fuse box or other point
compartments are abandoned permanently.
on a submain. If the submain supplies lighting no more
The relay-operated lantern is similar to the manually than one compartment, separate fuses must be installed
operated type except the relay housing is mounted on in the relay circuit.

4-38
 The operation of the lantern relays should be The case has two viewing windows at each end to
checked accroding to PMS requirements. When the check the condition of the four Navy-type BB-254/U
circuit is de-energized, the relay should operate and storage cells. Each cell contains a channeled section in
automatically turn on the lantern. The circuit may be which a green, a white, and a red ball denotes the state
de-energized by pressure exerted on the push switch of charge of the cell when viewed through the window
located on the relay housing. This simulates a loss of (table 4-10).
115-volt power. The relay should then dropout, causing
The lamp is rated at 6 volts, but it is operated at 8
the lantern to light.
volts to increase the light output. When operated with
To ensure satisfactory operation of hand lanterns, fully charged batteries, the lantern can be operated
check the batteries according to PMS schedules. Check continuously for about 3 hours without recharging. The
the batteries by operating the lantern and observing the batteries should be recharged as soon as possible after
brightness of the lamp. If the emitted light is dim, the green ball (10 percent discharged) has sunk to the
replace the batteries immediately. At this time, check bottom. The lanterns should be ckecked according to
the rubber boot on the switch for tears or cracks. PMS requirements; if the batteries require charging,
Replace immediately if the boot is defective. Ensure the they should be charged at a rate of 1 1/2 to 2 amperes
switch is also grounded to the ship’s hull. A simple test until all indicator balls are floating at the indicator line.
with a multimeter will verify this. If the battery is completely discharged, it will require
from 20 to 25 hours to recharge it. After the charging
Lanterns located in spaces where the normal voltage has remained constant at 10 volts for 1 hour, the
temperature is consistent] y above 90°F should be charge may be discontinued
checked more often. For example, in boiler rooms the
batteries may have to be replaced weekly to ensure When necessary, add pure distilled water to keep the
adequate illumination from the lanterns. electrolyte level at the indicator line marked on the front
of the cell. Do not add water above the electrolyte level
The NAVSEA symbol number 104 (not shown) dry line because overfilling will nullify the nonspill feature
battery type (hand carrying or head attaching) of lantern of the battery and may cause the electrolyte to spurt out
is used for damage control purposes. It is generally through the vent tube. However, if the electrolyte level
stored in damage control lockers. This lantern’s battery is not at the indicator line, the charge indicator balls will
container may be clipped over the wearer’s belt; the not indicate the correct battery state of charge.
lamp and reflector assembly can be hand held or worn
Portable flood lanterns are often referred to as
on the head or helmet for repair party personnel by a
headband attached to the light. damage control lanterns because they are used by
damage control personnel to furnish high-intensity
illumination for emergency repair work or to illuminate
Portable Flood Lanterns inaccessible locations below deck.

The NAVSEA symbol number 105 portable flood Submarine Identification Lights
lantern (fig. 4-34, view C) consists of a sealed-beam
lamp enclosed in a built-in lamp housing equipped with Submarines may display, as a distinctive means of
a toggle switch. The lamp housing is adjustable, identification, an intermittent flashing amber beacon,
mounted on a drip-proof, acid-resistant case. visible for 360° around the horizon. The sequence of

Table 4-10.—State of Charge of Portable Flood Lanterns

4-39
operation will be one flash per second for 3 seconds system is used. These 24-volt dc lights are spraytight
followed by a 3-second off period. fixtures provided with a 25-watt, single
SMALL BOAT AND SERVICE vertical-filament lamp. These fixtures are constructed
CRAFT LIGHTS of polycarbonate material with a built-in metal shield to
On many crafts and small boats that are less than 50 provide the required arc of visibility. These fixtures are
meters (165 feet) in length, a 24-volt dc navigation light shown in figure 4-35.

Figure 4-35.—Small boat and service craft lights.

4-40
 SUMMARY maintenance. For a more thorough description of the
In this chapter we discussed shipboard lighting material discussed, refer to Lighting on Naval Ships,
systems, light sources, lamps, fixtures, navigation NAVSEA publication 0964-000-2000, and NSTM,
lights, signal lights, searchlights, and their operation and chapters 300, 320, 330,422, and 583.

4-41
 CHAPTER 5

ELECTRICAL AUXILIARIES

Electrician’s Mates (EMs) are required to maintain

various types of electrical equipment aboard ship. This
chapter will introduce you to the operating principles of
some of the most widely used types of auxiliary
equipment and describe methods and procedures for
operating and maintaining them.

LEARNING OBJECTIVES

Upon completing this chapter, you will be able to

do the following:
1. Identify proper use and care of dc systems
including batteries, battery chargers, and small
craft starting system.
2. Identify the operating characteristics and
procedures for maintaining air conditioning,
refrigeration, and air compressor units.

3. Identify the care of and the maintenance

procedures for vent fog precipitators.
4. Identify the proper operating and maintenance
procedures for various deck equipment.
5. Identify proper operating and troubleshooting
techniques for maintaining electrohydraulic
elevators and steering gears.
6. Identify the operating characteristics of various
galley and laundry equipment.

STORAGE BATTERIES
Lead-acid storage batteries provide a cheap,
portable, rechargeable source of dc power. Batteries
have many uses including starting small boat engines
and acting as a source of backup power for the ship’s
gyro. The battery also functions as a voltage stabilizer
in the small craft electrical system and supplies
electrical power for a limited time when the electrical
load exceeds the output of the boat’s generator.

CONSTRUCTION

No matter the number of cells, lead-acid batteries

used in the Navy are basically the same in construction
and operation. The following components make up a
Figure 5-1.—Three-cell (6V) lead-acid battery.
typical lead-acid storage battery (fig. 5-1).

5-1
 1. Jar (monobloc). A container of suitable material atmospheric oxygen from entering the battery. The
in which a single cell is assembled valve allows small quantities of gas to escape when the
2. Cell. A unit consisting of positive and negative internal pressure exceeds the valve operating
plates, separators, a cell cover, and electrolyte, properly pressure.
assembled in a jar or one compartment of a monobloc 12. Positive terminal post. One of the two lead posts
case. that protrude through the top of the battery. The point
3. Element rest (bridge). The top surface of the at which the positive terminal connection is made to the
raised ribs forming the sediment spaces serves as the external circuit.
base upon which the elements rest.
13. Positive plate strap. A piece of conductive
4. Plate feet. Projections at the bottom of the plates material used to connect all the positive plates to a
(containing no active material). They serve as the point common post through the top of the battery.
of contact between the elements and the bridge, or
rest. 14. Positive plate. One of the elements that makes
up the positive group of a battery. Consists of a plate of
5. Sediment space. A space formed by raised ribs
lead peroxide, PbO2 placed in a cell and submersed in
built into the bottom of a battery jar or monobloc case.
electrolyte.
This space serves as a receptacle for residue from the
element plates and separators. The residue is due to
deterioration caused by the chemical action between the SPECIFIC GRAVITY
electrolyte and the plates across the separators. The
raised ribs also serve as baffles, preventing short circuits The specific gravity of a liquid is the ratio of the
between the negative and positive plates by keeping the weight of a certain volume of liquid to the weight of the
sediment from building up in any one area. same volume of water is called the specific gravity of
6. Separator. Spacers placed between positive and the liquid Mathematically, this can be expressed as
negative plates to prevent short circuiting. They maybe follows:
made of wood or microporous rubber.
7. Rubber retainer. Sheets of suitable,
nonconductive material are used in conjunction with the
separators to help hold the active material of the positive Where:
plates in place and to protect the separator from the
action of the positive material. They may be made of sp.gr. is the specific gravity
hard rubber or synthetic compounds, perforated or Wsample is the weight of a volume of the sample
slotted to allow free flow of the electrolyte. being measured
8. Negative plate. One of the elements that makes Wwater is the weight of the same volume of pure
up the negative group of a battery. Consists of a plate water
of pure sponge lead (Pb) placed in a cell and submersed
in electrolyte. The specific gravity of pure water is, by definition,
1.000. Sulfuric acid has a specific gravity of 1.830;
9. Negative plate strap. A piece of conductive
therefore, sulfuric acid is 1.830 times as heavy as water.
material used to connect all the negative plates to a
The specific gravity of a mixture of sulfuric acid and
common post through the top of the battery.
water varies with the strength of the solution from 1.000
10. Negative terminal post. One of the two lead (pure water) to 1.830 (pure acid).
posts that protrude through the top of the battery. The
point at which the negative terminal connection is made The electrolyte that is usually placed in a lead-acid
to the external circuit. battery has a specific gravity of 1.350 or less. Generally,
11. Vent plug (vented) or safety valve (sealed). In a the specific gravity of the electrolyte in standard storage
vented battery, a threaded plug of suitable material with batteries (table 5-1) is adjusted between 1.210 and
a vent hole is used to prevent electrolyte from splashing 1.220. However, the specific gravity of the electrolyte
out of the cell but still allow gases to escape. Sealed in batteries varies according to their intended
batteries use a one-way pressure valve to prevent use.

5-2
 Table 5-1.—Specific Gravity Range of Batteries

Hydrometer

As a storage battery discharges, the sulfuric acid is

depleted and the electrolyte is gradually converted into
water. This action provides a guide in determining the
state of discharge of the lead-acid cell.
The specific gravity of the electrolyte in a lead-acid
battery is measured with a hydrometer. In the syringe
type of hydrometer (fig. 5-2), part of the battery
electrolyte is drawn up into a glass tube by a rubber bulb
at the top.
The hydrometer float has a hollow glass tube
weighted at one end and sealed at both ends. A scale,
calibrated in specific gravity, is laid off axially along the
body (stem) of the tube. The hydrometer float is placed
inside the glass syringe, and the electrolyte to be tested
is drawn up into the syringe. This immerses the
hydrometer float into the solution. When the syringe is
held approximately in a vertical position, the
hydrometer float will sink to a certain level in the
electrolyte. The extent to which the hydrometer stem
protrudes above the level of the liquid depends on the
specific gravity of the solution. The reading on the stem
at the surface of the liquid is the specific gravity of the
electrolyte in the syringe.
Figure 5-2.—Type-B hydrometer.
The Navy uses two types of hydrometer bulbs, or
floats, each having a different scale. The type-A
hydrometer is used with submarine batteries and has to mix the electrolyte before a hydrometer reading is
three different floats with scales from 1.060 to 1.240, taken.
1.200 to 1.280, and 1.228 to 1.316. The type-B
hydrometer is used with portable storage batteries and CAUTION
aircraft batteries. It has a scale from 1.100 to 1.300. The
electrolyte in a cell should be at the normal level when Flush hydrometers daily with fresh water to
the reading is taken. If the level is below normal, not prevent inaccurate readings. Do not use storage
enough fluid will be drawn into the tube to cause the battery hydrometers for any other purpose.
float to rise. If the level is above normal, the electrolyte
will be weakened and the reading will be too low. If a Correcting Specific Gravity
hydrometer reading is taken immediately after water is
added, the reading will be inaccurate because the water The specific gravity of the electrolyte is affected by
tends to remain at the top of the cell. When water is its temperature. When the electrolyte is heated, it
added, the battery should be charged for at least 1 hour expands and becomes less dense, and its specific gravity

5-3
reading is lowered. When the electrolyte is cooled, it CAPACITY OF BATTERIES
contracts and becomes denser, and its specific gravity
reading is raised. In both cases, the electrolyte maybe The capacity of a battery is measured in
from the same fully charged storage cell. As you can ampere-hours. The ampere-hour capacity is equal to the
see, temperature can distort the readings. product of the current in amperes and the time in hours,
during which the battery is supplying this current. The
Most standard storage batteries use 80°F as the
ampere-hour capacity varies inversely with the
normal temperature to which specific gravity readings
discharge current. The size of a cell is determined
are corrected. To correct the specific gravity reading of
generally by its ampere-hour capacity. The capacity of
a storage battery, add 1 point to the reading for each 3°F
a cell depends upon many factors, the most important of
above 80°F and subtract 1 point for each 3°F below
these are as follows:
80°F.
• The area of the plates in contact with the
Adjusting Specific Gravity electrolyte
• The quantity and specific gravity of the
Only authorized personnel should add acid to a electrolyte
battery. Never add acid with a specific gravity above
• The type of separators
1350 to a battery.
• The general condition of the battery (degree of
If the specific gravity of a cell is more than it should
sulfating, plates buckled, separators warped,
be, you can reduce it to within limits by removing some
sediment in bottom of cells, etc.)
of the electrolyte and adding distilled water, Charge the
battery for 1 hour to mix the solution. Then take the • The final limiting voltage
hydrometer readings. Continue the adjustment until
you obtain the desired true readings. STORAGE BATTERY RATING

Mixing Electrolyte Storage batteries are rated according to their rate of

discharge and ampere-hour capacity. Most batteries
(except aircraft and some used for radio and sound
The electrolyte of a fully charged battery usually
systems) are rated according to a 1 10-hour rate of
contains about 38 percent sulfuric acid by weight or
discharge—that is, if a fully charged battery is
about 27 percent by volume. In preparing the
completely discharged during a 10-hour period, it is
electrolyte, use distilled water and sulfuric acid. New
discharged at the 10-hour rate. For example, if a battery
batteries may be delivered with containers of
can deliver 20 amperes continuous y for 10 hours, the
concentrated sulfuric acid of 1.830 specific gravity or
battery has a rating of 20 x 10, or 200 ampere-hours.
electrolyte of 1.400 specific gravity. You must dilute
Thus the 10-hour rating is equal to the average current
both of these with distilled water to make electrolyte of
that a battery is capable of supplying without
the proper specific gravity. For diluting the acid, you
interruption for an interval of 10 hours. (NOTE:
should use a container made of glass, earthenware,
Aircraft batteries are rated according to a 1-hour rate of
tubber, or lead When mixing electrolyte, ALWAYS
discharge.) Some other ampere-hour ratings used are
POUR ACID INTO WATER— never pour water into
6-hour and 20-hour ratings.
acid. Pour the acid slowly and cautious] y to prevent
excessive heating and splashing. Stir the solution All standard batteries deliver 100 percent of their
continuously with a nonmetallic rod to mix the heavier available capacity if discharged in 10 hours or more, but
acid with the lighter water to keep the acid from sinking they will deliver less than their available capacity if
to the bottom. When concentrated acid is diluted, the discharged at a faster rate. The faster they discharge,
solution becomes very hot. the less ampere-hour capacity they have.

NOTE: Only use and store premixed electrolyte on As specified by the manufacturer, the low-voltage
U.S. Navy ships. The use and storage of acid for the limit is the limit beyond which very little useful energy
purpose of preparing electrolyte or for the adjustment of can be obtained from a battery. For example, at the
specific gravity are authorized only for shore activities conclusion of a lo-hour discharge test on a battery, the
or for ships designated as intermediate maintenance closed-circuit voltmeter reading is about 1.75 volts per
activities (IMAs). cell and the specific gravity of the electrolyte is about

5-4
1.060. At the end of a charge, its closed-circuit battery is 60/1.5, or 40 ampere-hours. You can
voltmeter reading while the battery is being charged at determine the number of ampere-hours expended in any
the finishing rate is between 2.4 and 2.6 volts per cell. battery discharge by using the following items:
The specific gravity of the electrolyte corrected to 80°F
1. The specific gravity when the battery is fully
is between 1.210 and 1.220. In climates where the
charged
temperature is 40°F and below, authority may be
granted to increase the specific gravity to 1.280. 2. The specific gravity after the battery has been
dischargd
STATE OF CHARGE OF BATTERIES 3. The reduction in specific gravity per
ampere-hour
After a battery is discharged completely from full
Voltage alone is not a reliable indication of the state
charge at the lo-hour rate, the specific gravity has
of charge of a battery, except when the voltage is near
dropped about 150 points to about 1.060. You can
the low-voltage limit on discharge. During discharge,
determine the number of points the specific gravity
the voltage falls. The higher the rate of discharge, the
drops per ampere-hour for each type of battery. For each
lower the terminal voltage. Open-circuit voltage is of
ampere-hour taken out of a battery, a definite amount of
little value because the variation between full charge and
acid is removed from the electrolyte and is combined
with the plates. For example: complete discharge is so small—only about 0.1 volt per
cell. However, abnormally low voltage does indicate
injurious sulfation or some other serious deterioration
of the plates.

TYPES OF BATTERY CHARGES

The following types of charges maybe given to a

storage battery, depending upon the condition of the
battery:
• Initial charge

• Normal charge

• Equalizing charge

• Floating charge

• Emergency charge

For example, if 70 ampere-hours are delivered by Battery Initial Charge

the battery at the 10-hour rate or any other rate or
collection of rates, the drop in specific gravity is 70 x When anew battery is shipped dry, the plates are in
1.5, or 105 points. an uncharged condition. After the electrolyte has been
added, you must convert the plates into the charged
condition. You can accomplish this by giving the
batter y a long, low-rate initial charge. The charge is
given according to the manufacturer’s instructions,
which are shipped with each battery. If the
manufacturer’s instructions are not available, refer to
the detailed instruction in current directives.

For example, if the specific gravity of the previously Battery Normal Charge
considered battery is 1.210 when the battery is fully
charged and 1.150 when it is partly discharged, the drop A normal charge is a routine charge that is given
in specific gravity is between 1.210 and 1.150, or 60 according to the nameplate data during the ordinary
points. The number of ampere-hours taken out of the cycle of operation to restore the battery to its charged

5-5
condition. Observe the following steps when giving a BATTERY CHARGING RATE
normal charge:
Normally, the charging rate of Navy storage
1. Determine the starting and finishing rate from
batteries is given on the battery nameplate. If the
the nameplate data.
available charging equipment does not have the desired
2. Add water, as necessary, to each cell. charging rates, use the nearest available rates. However,
never allow the rate to be so high that violent gassing
3. Connect the battery to the charging panel and
occurs.
make sure the connections are clean and tight.
4. Turn on the charging circuit and set the current
through the battery at the value given as the
starting rate.
5. Check the temperature and specific gravity of
pilot cells hourly.
6. When the battery begins togas freely, reduce the
charging current to the finishing rate. BATTERY CHARGING TIME

A normal charge is complete when the specific Continue a charge until the battery is fully charged.
gravity of the pilot cell, corrected for temperature, is Take frequent readings of specific gravity during
within 5 points (0.005) of the specific gravity obtained the charge. Correct these readings to 80°F and
on the previous equalizing charge. compare them with the reading taken before the
battery was placed on charge. If the rise in specific
Battery Equalizing Charge gravity in points per ampere-hour is known, the
approximate time in hours required to complete the
charge is as follows:
An equalizing charge is an extended normal charge
at the finishing rate. It is given periodically to ensure
all the sulfate is driven from the plates and all the cells
are restored to a maximum specific gravity. The
equalizing charge is continued until the specific gravity
of all cells, connected for temperature, shows no change
for a 4-hour period. For an equalizing charge, you must
take readings of all cells every half hour. TEST DISCHARGE OF BATTERIES

The test discharge is the best method for you to

Battery Floating Charge
determine the capacity of a battery. Most battery
switchboards are provided with the necessary
You can maintain a battery at full charge by equipment for you to perform test discharges to
connecting it across a charging source that has a voltage batteries. If proper equipment is not available, a tender,
maintained within the limits of 2.13 to 2.17 volts per cell a repair ship, or a shore station may perform the test
of the battery. In a floating charge, the charging rate is discharge. A battery test discharge is required when one
determined by the battery voltage, rather than by a of the following conditions exists:
definite current value. The voltage is maintained
between 2.13 and 2.17 volts per cell with an average as 1. A functional test reveals a low output.
close to 2.15 volts as possible. 2. One or more cells are found to have less than
normal voltage after an equalizing charge.
Battery Emergency Charge 3. A battery cannot be brought to within 10 points
of normal charge of its specific gravity.
An emergency charge is used when you must
4. A battery has been in service 4 years.
recharge a battery in the shortest possible time. The
charge starts at a much higher rate than is normally used Always precede a test discharge by an equalizing
for charging. Use it only in an emergency, as this type charge. Immediately after the equalizing charge,
of charge may be harmful to the battery. discharge the battery at its 10-hour rate until the total

5-6
battery voltage drops to a value equal to 1.75 times the WARNING
number of cells in series or the voltage of any individual
cell drops to 1.65 volts. Keep the rate of discharge
A mixture of hydrogen and air can be
constant throughout the test discharge. Because
dangerously explosive. Do not permit
standard batteries are rated at the 10-hour capacity, the
smoking, electric sparks, or open flames near
discharge rate for a 100 ampere-hour battery is 100/10,
charging batteries.
or 10 ampres. If the temperature of the electrolyte at
the beginning of the charge is not exactly 80°F, correct
the time duration of the discharge for the actual TREATMENT OF ACID BURNS
temperature of the battery.
A battery at 100 percent capacity discharges at its If acid or electrolyte from a lead-acid battery comes
10-hour rate for 10 hours before reaching its into contact with the skin, wash the affected area as soon
low-voltage limit. If the battery or one of its cells as possible with large quantities of fresh water.
reaches the low-voltage limit before the 10-hour period Afterwards, apply a salve, such as petrolatum, boric
has elapsed, discontinue the discharge immediately and acid, or zinc ointment. If none of these salves are
determine the percentage of capacity using the available, clean lubricating oil will suffice. When you
following equation: wash the area, use large amounts of water. A small
amount of water might do more harm than good and
spread the acid burn. You can neutralize acid spilled on
clothing with diluted ammonia or a solution of baking
Where: soda and water.

C = percentage of ampere hour capacity available

SUMMARY
Ha= total hours of discharge
Ht = total hours for 100 percent capacity The information included in this section is an
For example, a 100-ampere-hour, 6-volt battery introduction to the operation and use of lead-acid
delivers an average current of 10 amperes for 10 hours. storage batteries aboard ship. For in-depth coverage,
At the end of this period, the battery voltage is 5.25 volts. you should refer to Naval Ships’ Technical Manual,
On a later test, the same battery delivers an average chapter 313.
current of 10 amperes for only 7 hours. The discharge
was stopped at the end of this time because the voltage
of the middle cell was found to be only 1.65 volts. The BATTERY CHARGERS
percentage of capacity of the battery is now 7/10 x 100, The U.S. Navy uses numerous types and styles of
or 70 percent. Thus the ampere-hour capacity of this battery chargers. A battery charger is designed to
battery is reduced to 0.7 x 100 = 70 ampere-hours. replace the electrical energy a lead-acid storage battery
Record the date for each test discharge on the has consumed (lost) while being used. The battery
storage battery record sheet. charger is essentially a regulated, constant supply with
adjustable outputs, current, and voltage. The battery
charger discussed in this chapter is the 24-302-BN-1
BATTERY GASSING Battery Charger.

When a battery is being charged, a portion of the

DESCRIPTION OF THE 24-302-BN-1
energy is dissipated in the electrolysis of the water in the
BATTERY CHARGER
electrolyte. Hydrogen is released at the negative plates
and oxygen at the positive plates. These gases bubble
up through the electrolyte and collect in the air space at The model 24-302-BN-1 battery charger is
the top of the cell. If violent gassing occurs when the designed to operate with an input voltage of 115 volts
battery is first placed on charge, the charging rate is too ac ±5 percent, at 60 Hz ±5 percent, single-phase, 20
high. If the rate is not too high, steady gassing, which amperes. The output is determined by the number of
develops as the charging proceeds, indicates that the cells selected to be charged (3, 4, 6, 12, or 18) and the
battery is nearing a fully charged condition. current rating selected (2, 8, 15, or 30 amperes).

5-7
 The battery charger shown in figure 5-3 has a single
unit enclosed in a dripproof enclosure. All parts are
accessible through the front hinged panel. The output
connections (jacks) for the cables to be cm.netted to the
batteries are located on the lower front of the panel. The
only moving parts of this charger are the adjustable
resistors, the rheostats, and the meters.

This type of battery charger has three selector

switches on the front panel. The output voltage is
selected by the voltage selector switch located on the
upper left side; the current selector switch is located on
the upper right side; the on/off selector switch is in the
middle between the voltage and current selector
switches.

OPERATION OF THE 24-302-BN-1

BATTERY CHARGER

The control and regulation is accomplished with

SCRs and associated circuitry. Figure 5-4 is a wiring
diagram of the battery charger. Please refer to this
diagram as you read about the operation of the battery
charger.

The first step you must take is to select the

number of cells to be charged. To do this, place the
voltage selector switch (S3) in the respective position
Figure 5-3.—Front view of Battery charger, model (3, 4, 6, 12, or 18). Then select the current rating to be
24-302-BN-1. used during charging with the current selector switch

Figure 5-4—Battery charger wiring diagram.

5-8
(S2) in the respective position (2, 8, 15, or 30 SMALL CRAFT ELECTRICAL
amperes). SYSTEMS
Energize the battery charger by placing the selector Small craft perform an important function in the
switch (S1) in the ON position. This will cause the
daily routines of all naval vessels. When their parent
SCRs to conduct during a portion of the input cycle of
the step-down transformer (T1). The amount of ships are at sea, they serve as duty lifeboats and also as
conduction of the SCRs is controlled by the feedback troop carriers or assault boats. In port, they are used for
signals fed from the magnetic amplifier (L1). This will transporting stores and liberty parties and for
establish a fixed voltage reference across the Zener conducting other ship’s business. Most small craft are
diode (CR13) through the control coil (L1), the linear driven by a diesel engine.
resistor (R4), and the temperature compensating resistor
(R5). The R5 resistor serves to change the preset output The electrical system covered here is representative
voltage during temperature changes by changing the of those found on a large number of ship’s boats and
current through the L1 control coil. The negative small craft. The electrical system consists of the engine
feedback is fed to the L1 coil through the resistors (R10
starting system and the battery charging system.
through R15) and the selector switch (S3B). The
current transformer (T2) output is determined by the
resistors (R6 through R9) through the selector switch ENGINE STARTING SYSTEM
(S2), which will determine the voltage across the
capacitor (C5) and the current through transformer T2.
When the output current exceeds the selected breakover The engine starting system on small boats is
voltage of the reference Zener diode (CR13), the current equipped with storage batteries (previously discussed),
flowing through the control coil of L1 from the black to a starting motor, and control circuitry.
white leads is in such a direction as to oppose the
reference voltage. ‘Ibis will lower the output voltage
until the excess current of the transformer (T2) is Starting Motor
accepted by the battery on charge and starts to
recharge. The starting, or cranking, motor is slow-voltage, dc
The shorted winding of the reactor (L1) connected series motor used to start internal combustion engines
to leads white/orange and white/yellow allows for the by rotating the crankshafts. It is flange-mounted on the
circulation of the harmonic currents and slows the engine flywheel housing and is supplied with current
respoonse time of the output of the magnetic amplifier to from the battery. All starting motors are similar in
changes in the control signals. This increases stability design and consist essentially of a frame, armature,
against transient signals generated by the ac supply and
brushes, field windings, and drive mechanism. The
the firing of the SCRs.
armature shaft is supported on bronze bearings equipped
The choke filter (L2) reduces the ripple of the dc with wick oilers. The number of field poles and brushes
output caused when the SCRs fire. varies according to the cranking requirements and the
The battery chargers in use today must meet operating voltage.
specification MIL-C-24095B. These battery chargers
can charge 1 to 18 cells and have a maximum current The starting motor has low resistance; it is designed
limit of 45 amperes. to operate under heavy load with relatively high
horsepower for short periods of time. The high
SUMMARY horsepower is accompanied by a high current that
creates considerable heat and, if operated for any
The discussion about the model 24-302-BN-1 considerable length of time, will result in failure of the
battery charger introduced you to the various
motor due to overheating. Hence the starting motor
components that make up the battery charger. Also
must be operated for not more than 30 seconds at a time
covered was the functions of the charger. Maintenance
on this equipment should be accomplished according to and at about 2-minute intervals to allow the heat to
the prescribed instructions from the manufacturer and dissipate. The starting current on most small boats is
installed PMS procedures. over 600 amperes.

5-9
 The starting motor is equipped with an overrunning The overrunning clutch drive starting motor
clutch drive mechanism (fig. 5-5) that transmits the provides positive engaging and disengaging of the
power from the motor to the engine. The drive starting motor drive pinion and the flywheel ring gear.
mechanism performs the following functions: This drive mechanism uses a shift lever that slides the
clutch and drive pinion assembly along the armature
1. Engages the drive pinion with the flywheel for
shaft so that it can be engaged and disengaged with the
cranking the engine. When the starting motor is
flywheel ring gear. The clutch transmits cranking
operated, the drive mechanism causes the drive
torque from the starting motor to the engine flywheel
pinion to mesh with the teeth of the flywheel ring
but permits the pinion to overrun the armature after the
gear, thereby cranking the engine.
engine starts. Thus power can be transmitted through
2. Provides a gear reduction between the drive the overrunning clutch in only one direction. This
pinion and the flywheel. The gear reduction is action protects the starting motor from excessive speed
necessary because the starting motor must rotate during the brief interval that the drive pinion remains
at a relatively high speed with respect to the with the flywheel ring gear after the engine has started.
engine cranking speed to produce sufficient
output power to crank the engine. Thus a gear When the shift lever is operated, the clutch
reduction ratio of 15 to 1 will permit the starting assembly is moved along the armature shaft until the
motor to rotate at 1,500 rpm while cranking the pinion engages with the flywheel ring gear. The
engine at 100 rpm. starting-motor contacts are closed when the movement
of the shift lever is completed, causing the armature to
3. Disengages the drive pinion and the flywheel
rotate, and thereby cranking the engine.
after the engine is started As soon as the engine
is started, the drive mechanism causes the drive Once the engine has started the speed of rotation of
pinion to disengage from the flywheel. The the engine flywheel causes the pinion to spin faster than
engine speed increases immediately and may the armature of the starting motor. This action causes
soon attain speeds up to 1,000 rpm. If the drive the pinion to spin independently or overrun. When the
pinion is allowed to remain in mesh with the starting-motor switch is opened, the shift lever releases,
flywheel, the engine would drive the starting causing the drive spring to pull the overrunning clutch
motor at speeds up to 15,000 rpm, resulting in drive pinion out of engagement with the engine flywheel
serious damage to the motor. ring gear.

Figure 5-5.—Starting motor with an overrunning clutch drive and a solenoid-operated switch.

5-10
 the plunger is pulled so that the pinion engages with the
flywheel ring gear. The pull-in coil draws a
comparatively heavy current necessary to complete the
plunger movement. The holding coil aids the pull-in
coil. Continuation of the plunger movement closes the
switch contacts, permitting the starter motor to crank the
engine. As soon as the solenoid switch is closed (and
the pinion shifted), the pull-in coil is shorted by the
switch contacts in the starting-motor circuit so that only
the holding coil is energized to retain the plunger in the
operated position.
When the starter switch is released, the tension of
the return spring in the drive assembly actuates the
plunger to open the circuit to the starting motor.
BATTERY CHARGING SYSTEM

Figure 5-6.—Solenoid switch diagram. For you to maintain the battery in a fully charged
condition, the discharge current must be balanced by a
Control Circuitry charging current supplied from an external source, such
as a battery-charging alternator. If the discharge current
The solenoid shown in figures 5-5 and 5-6 is used
exceeds the charging current for an appreciable period,
on some starting motors equipped with overrunning
the battery will gradually lose its charge. It will not be
clutch drives to close the circuit to the starting motor and able to supply the necessary current to the electrical
also to engage the pinion with the flywheel ring gear. It system.
is mounted on the motor frame, as shown in figure 5-5,
and has a pull-in coil and a holding coil provided with A belt-driven alternator is used on small boats and
a spring-loaded plunger. A heavy contact disk is service crafts. The alternator has several advantages
attached to one end of the plunger, and the other end is over the dc generator. It is smaller in size, requires less
maintenance, and supplies charging current at idling
connected by linkage to the shift lever. Both coils are
speed.
connected in series with a starter switch located on the
instrument panel (fig. 5-6). When the starter switch is A typical alternator electrical system wiring
operated, both coils are energized (from the battery) and diagram is shown in figure 5-7. The three-phase ac

Figure 5-7.—A typical alternator electrical system wiring diagram.

5-11
output of the stator is fed to a rectifier bridge consisting safety shutdown, an on-off control, and local and remote
of six silicon diodes, which are normally located in the indicators.
end bell of the alternator. The rotor of the alternator has
The following is a brief description of the
one coil and two 6-finger rotor halves. In effect, it is a
compressor controls and indicators shown on figure 5-8.
12-pole rotor. Direct current (for field excitation) is
supplied to the rotor coil through a pair of brushes and OIL PRESSURE GAUGE— Measures oil
slip rings. The rectifying diodes will pass current from pressure at the oil pump discharge.
the alternator to the battery or load but will not pass
WATER INJECTION PRESSURE GAUGE—
current from the batter y to the alternator.
Indicates the freshwater pressure in the water system
The voltage regulator is the only device used with manifold downstream of the freshwater falter.
the alternator. It can either be built into the case or
externally mounted away from the alternator. The AIR DISCHARGE PRESSURE GAUGE—
voltage regulator uses no mechanical contacts. It uses Indicates the air pressure in the compressed air receiver
only a solid-state circuitry, is a sealed unit, and does not downstream of the compressor and the dehydrator.
require adjustments. DEW POINT SAMPLING CONNECTION— A
The electrical equipment is designed to operate at a suitable instrument can be attached to this connection to
specific voltage irrespective of the speed of the prime measure the moisture content of the compressed air
mover (engine) and the alternator. discharging from the dehydrator into the air receiver
periodically.
SUMMARY LOCAL/REMOTE/RESET-EMER SHUT-
DOWN SELECTOR SWITCH— Gives remote
Small craft are exposed to the most extreme of emergent y stop control to the auxiliary control console
weather conditions and must, therefore, receive a great (ACC) when in the normal REMOTE position. The
deal of attention. Using the information given in the RESET position is used to reset the control circuitry
previous section, you should have no problem taking after a remote shutdown to permit restarting the
care of the normal maintenance requirements necessary compressor. The is a spring return from the RESET
to keep the small craft aboard ship operational. to LOCAL setting. It is mounted on the controller door.

MANUAL/AUTOMATIC-125 PSIG/AUTO-
AIR COMPRESSORS MATIC-120 PSIG SELECTOR SWITCH— This
There are many uses for compressd air aboard ship. operating mode selector switch is located on the
Some of these include operating pneumatic tools, controller door.
ejecting gas from guns, starting diesel engines, charging AIR DISCHARGE THERMOMETER—
and firing torpedoes, and operating automatic Indicates the compressed air temperature in the air
combustion control systems. Compressed air is receiver. It is mounted on top of the receiver.
supplied to the various systems by low-pressure
(LP—150psi or below), medium-pressure (151 to 1,000 OFF/ON SELECTOR SWITCH— Provides
psi), or high-pressure (HP—1,000 psi and above) air manual start-stop control of the compressor. It is
compressors. mounted on the controller door.

ANNUNCIATOR PANEL— Shows causes of

LP AIR COMPRESSOR
automatic safety shutdowns using shutdown alarm
lamps.
Most of the air compressors aboard ship operate on
the same principles, electrical requirements, and SEAWATER THERMOMETER— Indicates the
controls. Therefore, the model discussed is typical of temperature of the seawater discharging from the
most units installed aboard ship. compressor cooling system.

The air compressor (fig. 5-8) supplies the air for the SAFETY SHUTDOWN RESET PUSH
ship’s LP air system. The air compressor is BUTTON— Resets the control circuitry after an
direct-driven by an electric motor through a flexible automatic shutdown is initiated by any of the
coupling. It has a manual and two automatic operating compressor safety devices. If not pressed to reset, the
modes (either at the low or high range), an automatic compressor cannot be restarted.

5-12
Figure 5-6.—A typical low pressure air compressor.

5-13
 LAMP TEST PUSH BUTTON— Checks for 1. The control relay (SCR) in the low-voltage
burned-out fault indicator lamps. It is located on the circuit is energized. The SCR contacts in the
annunciator panel. high-voltage circuit close, energizing the undervoltage
relay (UV). The UV contacts close, lighting the remote
LOADED RUNNING TIME METER— Records
ENABLE RUNNING lamp, making power available to
the time in hours that the compressor is operated in a
the safety shutdown circuits and to the contractors, the
loaded condition.
relays, the switches, and the solenoids in the
TOTAL RUNNING TIME METER— Records high-voltage circuit.
the total compressor operating time in hours for both 2. When the UV contacts close, the motor
loaded and unloaded operating conditions.
contactor (M) is energized. This closes the M contacts
ENABLE RUNNING LAMP (WHITE)— in the high-voltage circuit to start the motor. the M
Indicates that the compressor is in an operative contacts in the low-voltage circuit close at the same
condition, whether or not the machine is actually time, energizing the LOADED RUNNING TIME
running. It is located on the controller door. meter (LHM), the TOTAL RUNNING TIME
meter (ETM), both local and remote MOTOR
MOTOR RUNNING LAMP (GREEN)— RUNNING lamps, and the dehydrator refrigeration
Indicates that the compressor is running in either a pump motor.
loaded or unloaded condition. It is located on the
controller door. 3. The injection water solenoid valve (SV1) and
the two timing relays (4TR and 6TR) are energized at
OVERLOAD RESET PUSH BUTTON— Resets the same time as the motor contactor.
the controller overload relay after an automatic
4. Actuation of SV1 opens the valve to permit the
shutdown is caused by a motor overload. If not pressed
flow of injection water. Relay 4TR is a timed-to-close
to reset, the compressor cannot be restarted.
(on-delay) relay that closes 2 minutes after it is
FRESHWATER LEVEL SIGHT HOLE— energized to make the high dew point temperature
Allows checks to be made to ensure sufficient water is switch (HDP) operative in the safety shutdown circuit.
in the holding tank to permit starting the compressor. Relay 6TR is a timed-to close (on-delay) relay that
The compressor must be shut down and repressurized closes 12 to 15 seconds after it is energized to make the
before the sight hole plug can be removed. It is located oil pressure and injection water pressure switches (PS4
in front of the separator-holding tank. and PS3) operative in the safety shutdown circuit. (This
permits start-up by preventing safety shutdown while
COMPRESSOR DISCHARGE THERMOM-
the lubricating oil and injection water system pressures
ETER— Indicates the temperature of the air
build up to normal values.)
discharging from the compressor. It is mounted on the
separator-holding tank and indicates the air temperature 5. The compressor is now running fully loaded
in the separator. under control of the receiver air-pressure switch
(PS1) and with all control and shutdown circuits
As you read this section, look at the air compressor operative.
schematic diagram (fig. 5-9), as the sequence of the
manual and automatic modes of operation of the LP air NOTE: The motor will not start when the selector
compressor, the injection water level control, the switch (3SEL) is turned ON unless the pressure
condensate drain control, and the shutdown system are switch (PS1) is closed and the air discharge
discussed. The numbers/letters in parentheses temperature switch level control, the condensate
correspond to the electrical components on the drain control, and the shutdown system are
schematic. de-energized. The numbers/letters in parentheses
correspond to the electrical components on the wiring
diagram.
Manual Operation
The compressor is stopped in the MANUAL mode
The operator places the controller in the manual of operation by one of the following actions:
mode of operation by positioning the selector switch
(1SEL) to the MANUAL position and turning the • The high receiver air-pressure switch (PSI)
selector switch (3SEL) to the ON position. This initiates opening at 125 psig rising pressure
the following sequence:

5-14
Figure 5-9.—Air compressor schematic diagram.

5-15
Figure 5-9.—Air compressor schematic diagram.

5-16
 • The high air temperature switch (TS) closing Table 5-2.—Automatic Mode Settings of a Typical LP Air
Compressor
• The high injection water level switch (LS1)
closing
• The low oil pressure switch (PS4) closing after
the timing relay (6TR) has timed closed
• The low injection water pressure switch (PS3)
closing after the timing relay (6TR) has timed
closed
• The low injection water level switch (LS2)
closing
• The high condensate sump water level switch
(LS6) closing
Turning the selector switch (3SEL) to the ON
• The high dew point temperature switch (HDP) in position initiates the following sequence:
the dehydrator closing after the timing relay NOTE: The following operating sequence
(4TR) has timed closed describes control functions with the selector switch
• The undervoltage relay (UV) contacts opening (1SEL) in the AUTOMATIC-125 PSIG position under
control of the pressure switch (PS1). With the selector
• The motor overload (OL) contacts opening switch in the AUTOMATIC- 120 PSIG position, control
• A fuse (1FU, 2FU, 3FU, or 4FU) failing functions are the same but are under the control of the
pressure switch (PS2).
• The operator turning the selector switch (3SEL)
1. The control relay (5CR) in the low-voltage
to the OFF position
circuit is energized. The 5CR contacts in the
• The operator pressing the remote EMER STOP high-voltage circuit close to energize the undervoltage
push button, provied the selector switch (2SEL) relay (W). The white ENABLE RUNNING light
(WIL) is-lit on the controller door.
is in the REMOTE position
2. The UV interlocks close to provide power to
NOTE: If an automatic safety shutdown occurs, the
other parts of the control system and energize the remote
remote SAFETY ALARM will be energized by the
ENABLE RUNNING light.
control relay (2CR). If a manual shutdown occurs, the
3. The timing relay (1TR) and control relay (1CR)
remote EMER STOP lamp will be lit. If any shutdown
are energized and the following actions occur
occurs in the MANUAL operating mode, both remote
simultaneously:
and local ENABLE RUNNING and MOTOR
RUNNING lamps will be extinguished • One set of timed-to-open (off-delay) relay 1TR
contacts close to energize the motor contactor (M),
which closes the M contacts in the motor wiring leads
Automatic Operation to start the motor. The M contacts in the low-voltage
circuit also close to energize the TOTAL RUNNING
TIME meter (ETM) and the local and remote MOTOR
Figure 5-9 is a schematic diagram of the air RUNNING lights.
compressor control system. Please follow figure 5-9 as
• A second set of 1TR contacts closes at the same
the step-by-step operation of the automatic operation is
time as the control relay (1CR). Normally closed (NC)
discussed. The controller is placed in the automatic contacts open in the circuit to the unloader solenoid
mode of operation by the selector switch (1SEL) (table valve (SV4) to prevent operation of the valve. Other
5-2) being placed in either the AUTOMATIC-125 PSIG 1CR normally open (NO) contacts close to energize the
or AUTOMATIC-120 PSIG position. LOADED RUNNING TIME meter (LHM).

5-17
 • Also energized simultaneously are the injection • The low injection water pressure switch (PS3)
water solenoid valve (SV1) and two timing relays (4TR closing after the timing relay (6TR) has timed
and 6TR). The SV1 valve opens, permitting flow of closed.
injection water. The 4TR begins a 2-minute • The undervoltage relay (UV) contacts opening.
timed-to-close (on-delay) time out. The 6TR begins a
12- to 15-second on-delay time out. • The motor overload (OL) contacts opening.

• The timing relay (6TR) contacts close in 12 to 15 • A fuse (1FU, 2FU, 3FU, or 4FU) failing.
seconds, making the oil pressure and the injection water • Turning of the selector switch (3SEL) to the OFF
pressure switches (PS4 and PS3) operative in the safety position.
shutdown circuitry.
• Pressing of the remote EMER STOP pushbutton,
• The timing relay (4TR) contacts are timed to provided the selector switch (2SEL) is in the
close in 2 minutes, making the high dew point REMOTE position.
temperature switch (HDP) effective in the safety
NOTE: If an automatic safety shutdown occurs, the
shutdown circuitry.
remote SAFETY ALARM will be energized by the
• The compressor is now running fully loaded control relay (2CR). If a manual emergency shutdown
under control of the receiver air-pressure switch (PS1) occurs, the remote EMER STOP lamp will be lit. When
and with all control and shutdown circuits operative. the unit is shut down, both remote and local ENABLE
RUNNING and MOTOR RUNNING lamps will be
NOTE: The motor will not start when the selector
extinguished Both of these lamps will remain lit during
switch (3SEL) is turned ON unless the pressure switch the 10-minute unloaded run as a result of high air
(PS1) is closed and the air discharge temperature switch pressure. Should the compressor not reload and it stops
(TS) is open. This prevents the compressor from after the 10-minute time out, the MOTOR RUNNING
starting when there is adequate receiver air pressure or lamp will be extinguished, but the ENABLE
when an abnormal temperature condition exists. RUNNING lamp will remain lit.
The compressor is stopped in the
Injection Water Level Control
AUTOMATIC-125 psig mode of operation by one of
the following actions:
The level of injection (fresh) water level in the
• The high receiver pressure switch (PS1) opening, separator-holding tank is controlled by the operation of
which de-energizes the control relay (1CR) and float switches (LS3 and LS4) and solenoid valves (SV5
off-delay timing relay (1TR). The 1TR contacts and SV6).
time open in 10 minutes; this allows the If the injection water rises to the high-level switch
compressor to run for 10 minutes in an unloaded setting, the switch (LS3) closes, energizing the on-delay
condition before automatically stopping. timing relay (2TR). When the 2TR relay times closed
• The high air temperature switch (TS) closing. in 6 to 8 seconds, provided LS3 remains closed, the
solenoid valve (SV6) is energized to drain the tank
• The high injection water level switch (LS1)
If the water level in the separator-holding tank drops
closing.
low enough to close the low-level switch (LS4), the
• The low injection water level switch (LS2) timing relay 3TR is energized. If the 3TR contacts are
closing. allowed to time closed (6 to 8 seconds), provided LS4
remains closed, the solenoid valve (SV5) is energized
• The high condensate sump water level switch to add water from the freshwater supply to the injection
(LS6) closing. water system.
• The high dew point temperature switch (HDP) in
Condensate Drain Control
the dehydrator closing after the timing relay
(4TR) has timed closed.
The dehydrator condensate sump is drained by the
• The low oil pressure switch (PS4) closing after solenoid valve (SV7) under control of the normally
the timing relay (6TR) has timed closed closed level switch (LS5). When the liquid level in the

5-18
condensate sump reaches the high-level setting of LS5, protection is provided by the safety relief valve on the
the switch opens to de-energize the control relay (3CR). receiver.
This opens the 3CR contacts, which, in turn,
The selector switch (1SEL) is set for
de-energizes the SV7 solenoid. The normally open
AUTOMATIC-120 psig operation. Shutdown control
solenoid valve opens to drain the condensate sump.
is the same except that the shutdown sequence is
When the liquid level drops to the low-level setting of
LS5, the switch closes to energize 3CR and SV7. This initiated by the opening of the pressure switch (PS2) at
shuts the drain valve. a rising air pressure of 120 psig.

HIGH AIR DISCHARGE TEMPERATURE.—

Shutdown System Abnormally high air temperature at the compressor
discharge closes the temperature switch (TS),
energizing the control relay (14CR). The 14CR contacts
Automatic shutdown of the compressor occurs
when one or more of the following conditions exist: close to light the HIGH AIR DISCHARGE
TEMPERATURE light on the annunciator panel and to
• High air receiver pressure energize the latching relay (2CR). Normally closed
2CR contacts in the high-voltage circuit open to
• High air discharge temperature
de-energize UV, which de-energizes M. This stops the
• High dew point temperature at the dehydrator motor. Other 2CR contacts close to sound the remote
safety shutdown alarm and to maintain power to 14CR.
• High or low injection (fresh) water levels
This keeps the HIGH AIR DISCHARGE
• Low lube oil pressure TEMPERATURE light illuminated even if TS opens
after the compressor has shut down, allowing operators
• Low injection water pressure
to determine the cause of the shutdown.
• High condensate sump level HIGH DEW POINT TEMPERATURE.—
HIGH AIR RECEIVER PRESSURE.— When Abnormally high dew point temperature in the
the compressed air pressure at the receiver exceeds the dehydrator will close the temperature switch (HDP),
rising pressure setting of the pressure switch (PS1 or and if the relay (4TR) has closed, energize the relay
PS2), one of the following shutdown sequences is (15CR). The 15CR contacts close to light the HIGH
initiated: DEW POINT lamp on the annunciator panel and to
energize 2CR. This functions to stop the compressor,
The selector switch (1SEL) is in the MANUAL
sound the alarm, and maintain the indication (through
mode of operation. The compressor will be
automatically y stopped by the pressure switch (PS1) 15CR).
tripping at 125 psig rising pressure. This will HIGH WATER LEVEL.— An excessively high
de-energize the main motor contactor (M), which opens water level in the separator-holding tank will close the
the M contacts in the motor leads. level switch (LS1), energizing the relay (11CR). The
The selector switch (1SEL) is in the 11CR contacts close to light the HIGH SEP/HLDG
AUTOMATIC-125 psig operating position. The TANK LEVEL lamp on the annunciator panel and
compressor is under control of the normally closed energize the on-delay (timed-to-close) timing relay
contact of the pressure switch (PS1). When a rising (STR). The 5TR contacts close in 3 to 5 seconds to
pressure of 125 psig causes PS1 to open, compressor energize 2CR (if LS1 has remained closed). The 2CR
shutdown is delayed for 10 minutes by the timing relay contacts actuate to shut down the motor, sound the
(1TR). The control relay (1CR) is de-energized by the shutdown alarm, and maintain the indication (through
opening of PS1. This initiates closing of the air intake 11CR).
butterfly valve (solenoid SV4 energized) and opening
of the air bypass line. The compressor runs unloaded LOW WATER LEVEL.— An excessively low
with discharge air recycling back to the compressor water level in the separator will close the level switch
inlet. After 10 minutes (provided PS1 remains open), (LS2) and energize the relay (12CR). The 12CR
the 1TR contacts time open to stop the compressor drive contacts affect 5TR and 2CR. They also light the LOW
motor by de-energizing the motor contactor (M). SEP/HLDG TANK LEVEL lamp on the annunciator
During the 10-minute time out, excessive air pressure panel.

5-19
 LOW OIL PRESSURE.— An abnormally low oil REFRIGERATION AND
pressure will close the pressure switch (PS4) and, after AIR-CONDITIONING SYSTEMS
the relay (6TR) has closed, energize the relay (17CR).
The 17CR contacts close, illuminating the LOW OIL As an EM, you must have a knowledge of the
PRESSURE light on the annunciator panel and refrigeration and air-conditioning systems. In this
energizing 2CR. The 2CR contacts initiate a safety section, you will learn about starting, operating, and
shutdown and maintain the indication through 17CR. stopping some types of refrigeration systems.

LOW INJECTION WATER PRESSURE.— An

abnormally low injection water pressure will close the
REFRIGERATION SYSTEM
pressure switch (PS3) and, if 6TR has closed, energize
the relay (16CR). The 16CR contacts close,
illuminating the LOW INJECTION WATER The function of the ship’s stores refrigeration
PRESSURE light on the annunciator panel and system is to provide refrigeration in the freeze and chill
energizing 2CR. The 2CR initiates a safety shutdown storerooms to preserve perishable foods. The
and maintains the indication through 16CR. refrigerant is supplied by two refrigeration plants. The
plants can be operated singly or together.
HIGH CONDENSATE LEVEL.— An
excessively high condensate level in the dehydrator
sump causes the level switch (LS6) to close, energizing
Plant Components
13CR and lighting the HIGH CONDENSATE LEVEL
light on the annunciator panel. The 13CR also energizes
STR, which will time closed to energize 2CR and initiate Each plant consists of a 1. l-ton reciprocating
a safety shutdown. compressor assembly, motor controller, condenser,
receiver, dehydrator, heat exchanger, gauge board, and
Whenever the compressor drive motor is shut down associated controls. The refrigeration plants supply
by the de-energizing and opening of the motor contactor refrigerant (R-12) to the cooling coils located in the
(M), the solenoid valves (SV1 and SV7) are three storage spaces. The storage spaces are the freeze
simultaneously de-energized. storeroom and two chill storerooms. The freeze
storeroom is maintained at 0°F. The chill storerooms
• Solenoid valve SV1 closes in the injection (fresh) are normally maintained at 33°F.
water supply line to stop the flow of injection
water to the compressor intake. Table 5-3 contains a list of the safety control
• Solenoid valve SV7 opens in the condensate switches, the magnetic relays, the contractors, and the
indicating devices of the 1.1 -ton refrigeration
drain line to drain the condensate sump and
repressurize the compressor. compressor assembly. It shows the location, functions,
and settings of the individual units.

MAINTENANCE
Plant Operation

Scheduled maintenance should be performed

according to the Planned Maintenance System (PMS). The compressor can only be energized from the
motor controller, which is located in the auxiliary
machinery room or reefer flats. Besides providing
SUMMARY start/stop operation of the plant, the controller has a
two-position selector switch labeled LOCAL and
NORMAL. The difference in plant operation between
The air compressor discussed in this section the two positions is that in the NORMAL position the
contains information on the basic operating principles plant can be shut down from either the remote or local
of most compressors seen in the Fleet. While the location.
compressor aboard your ship may not be this type, the
principles discussed here should prove valuable to you To help you understand the refrigeration
in maintaining those found aboard any ship. plant operation, refer to the wiring diagram in

5-20
Table 5-3.—Switches, Relays, Contactors, and Indicating Devices of Refrigeration Equipment

5-21
Figure 5-10.—Refrigeration plant wiring diagram.

5-22
figure 5-10. To start the compressor, turn the selector (4M) is normally closed in the de-energized condition,
switch to LOCAL or NORMAL operation. Then press keeping the oil heater energized This contact is opened
the start button. Provided the contacts for OL, WF, and by the M coil at the same time that 1M, 2M, and 3M are
DP are closed, the UV relay will be energized and close closed.
its UV-1 contacts across the start switch contacts, which The suction pressure switch (SP) is connected in
will maintain the holding circuit for the UV relay. At series with the UV-2 contacts. It is used to sense the
the same time, the UV-2 contacts close, causing the main pressure of the compressor suction line for automatic
contactor coil (M), the relay (TR), and the elapsed time operation. The switch stops the compressor when the
meter (ETM) to be energized. This causes the M coil to pressure is reduced to a level corresponding to the open
close its contacts (1M, 2M, and 3M), and then the motor setting (5 in. Hg vacuum). The compressor is
should start. automatically started again when the SP switch contacts
The timing relay (TR) is energized and will open its close and the suction line pressure increases to the
TR-2 contacts after a 10-second time delay. This should closed setting (8 psig). The cycle starts over again to
allow the oil pressure enough time to increase and close maintain the refrigerated rooms at their normal
the oil pressure switch contact (OP). If the oil pressure temperatures.
does not close its OP contacts, the compressor will stop If any of the contacts (WF, DP, OP, or OL) open, the
after 10 seconds when the TR-2 contacts open. The motor will stop and will have to be started manually.
ETM will run only as long as the motor is energized or
running.
80-TON AIR-CONDITIONING UNITS
The IR relay is energized at the time the start button
is pushed. It is maintained by the IR-1 contact across The function of the 80-ton air-conditioning units
the start switch contact. You will notice that the contact (fig. 5-11) installed on board the FFG-7 class fast frigate

Figure 5-11.—80-ton compressor unit assembly.

5-23
is to provide the chilled water for the air-conditioning SEAWATER FAILURE SWITCH.— T h e
system throughout the ship. Ships of this class have a seawater failure switch should be set to close at 15 psig
minimum of three identical units installed. and open at 5 psig.

The compressor is a reciprocating, single-acting FRESHWATER FAILURE SWITCH.—The

freshwater failure switch should be set to close at 45 psig
unit. It is equipped with a capacity control system, a
and open at 3 psig.
pressure relief valve, and an oil pressure failure switch.
WATER CHILLER OPERATING THERMO-
STATS.— The water chiller operating thermostats are
Control Devices
set to close when the chilled water reaches 44°F and
open when the water temperature reaches 40°F.
The operation and pressure setting of the individual
control devices are discussed separately in this section LOW-LIMIT THERMOSTATS.— The low-limit
thermostats are backup thermostats for the chiller
to help you understand the operation of the 80-ton
operating thermostat. If the chilled water temperature
air-conditioning unit. would decrease below the 40°F level, the low-limit
OIL PRESSURE SAFETY SWITCH.— The oil thermostat would open at 36°F. The low-limit
thermostat will not close until the chilled water
pressure safety switch protects the compressor in case
temperature rises to 40°F. The compressor operation
of insufficient oil pressure. The switch is wired to the would not begin until the chiller operating thermostat
compressor motor controller to stop the compressor if contacts close.
one of the following situations exists:

1. The oil pressure drops to 12 psi or less during Operation

operation
2. The oil pressure at start-up does not build to a To help you understand the following discussion of
satisfactory minimum of 18 psi. the operation of the air-conditioning compressor, refer
The oil pressure safety switch is interlocked with a to the wiring diagram in figure 5-12.
time delay relay in the motor controller to permit a short The compressor can only be energized from the
operating period (10 to 15 seconds) at start-up to allow motor controller, which is located near the equipment.
the oil pressure to develop. The switch is wired so that Besides providing Start/stop operation of the unit, the
when the compressor is stopped by the loss of oil controller has a two-position selector switch, labeled
pressure action, it must be restarted at the motor LOCAL or LOCAL/REMOTE. When in the
LOCAL/REMOTE position, the compressor can be
controller.
stopped remotely by the use of the emergency (EM) stop
SOLENOID VALVE.— The solenoid valve is a button located in the control console room.
pilot-operated, piston-type valve and is operated by an
electric coil. The valve is open when the current is on To start the compressor, turn the selectors witch to
the LOCAL or LOCAL/REMOTE position and press
and closed when the current is secured The solenoid
the start button. This will energize the UV relay,
valve is wired to the water chiller operating thermostat
provided contacts OL, WFS1 and 2, HP, and LT are
for control with the system in operation. The solenoid closed The W relay will close its UV-1 contacts,
valve shuts when chilled water reaches the minimum which are connected across the start switch and is the
temperature. maintaining circuit for the UV relay. At the same
instant, the UV-2 contacts close energizing the 1CR
HIGH-PRESSURE CONTROL SWITCH.— relay, closing its 1CR-1 maintaining contacts. Also,
The high-pressure control switch should be set to open UV-3 contacts will close, energizing the timing relay
at 160 psig and close at 140 psig. (TR). This closes the TR-IC contacts, energizing the
M-coil contactor. Contacts M-1, M-2, and M-3 will also
LOW-PRESSURE SUCTION SWITCH.— The close, connecting the motor across the line. Contacts
low-pressure suction switch should be set to close at 40 M4 close to energize the remote run light in the control
psig and open at 20 psig. console.

5-24
Figure 5-12.—80-ton air-conditioning compressor wiring diagram.

5-25
 The OP contacts should close before the TR contacts As soon as the chilled water temperature rises to or
open, which are time opening. The unit should operate above the cut-in setting of the operating thermostat, the
normally and will be stopped and started by the LP solenoid opens and allows liquid refrigerant to flow to
the pilot thermal expansion valve. The pilot supplies
switch.
pressure to the main thermal expansion valve and moves
During operation, opening the OP, WFS, HP, or LT it to the OPEN position. Liquid refrigerant is thus
contacts will cause the W relay to be de-energized, allowed to flow to the chiller. The suction pressure rises,
causing the cut-in setting of the low-pressure control
drop out, and stop the motor. The normally closed UV-5
switch to close its contacts. This starts the compressor
interlock contacts will close and complete the circuit to motor.
the safety shutdown alarm.

Loss of voltage for any reason will cause the UV SUMMARY

relay and 1CR relays to drop out, stopping the unit. On
restoration of the voltage, you need to press the start In the previous section, the function and the
button to restore the compressor to normal operation. equipment used in air conditioning and refrigeration
This feature is known as low-voltage protection were described. Also, the operation of air compressors
(LVP). and the refrigeration and air-conditioning systems are
covered. It should be apparent that this equipment is
An overload will cause the OL contacts to open, stop very important. If you do not understand a system
the motor, and energize the alarm. To restore operation, completely, go back and review before continuing on to
you will have to press the stop-reset button and then the the next sections.
start button.

To stop the compressor manually, all you need to do PENDULUM WINDOW

is press the stop-reset button. WIPER

When the selector switch is in the The window wiper (fig. 5-13) is an extremely
LOCAL/REMOTE position, the emergency simple, rugged piece of equipment. The information in
(EM-STOP) button in the console is energized. If the the following paragraphs will give you enough
information to enable you to operate, troubleshoot, and
EM-STOP button is pressed for any reason, the ESR1
repair almost any problem that occurs with the wiper.
relay will become energized, which will close its
contacts ESR1-1. This causes the ESR2 relay to be
energized close its maintaining contacts ESR2-1 and DESCRIPTION
ESR2-2, and open contacts ESR2-3. This sequence
shuts down the compressor. The ESR2-1 contacts are The pendulum window wiper is a variable-speed,
only maintaining contacts for the ESR2 relay. The electric motor-driven oscillating arm wiper with a
totally enclosed drive unit. The wiper is equipped with
ESR2-2 contacts will energize the EM-STOP indicating
a heated arm for operation under icing conditions. The
light in the control console.
entire unit weighs 20 pounds and is mounted on the
The OT and solenoid circuit operates to cut in or cut bulkhead over the window it serves. The wiper is
suitable for use on fixed or hinged windows and can be
out the refrigerant to the pilot thermal expansion valve.
adjusted to ensure correct blade pressure and travel.
This causes the main thermal expansion valve to close,
cutting off the supply of refrigerant to the water chiller. The window wiper runs on dc voltage. It takes
With the solenoid valve closed and the supply of liquid 115-volts, single-phase ac power from the ship’s service
line and rectifies it through a full-wave bridge rectifier.
refrigerant cut off to the chiller, the compressor
continues to operate for a short period of time until the
suction pressure drops to the cutout setting of the CONSTRUCTION
low-pressure control switch. The switch contacts then
open and the compressor motor stops. The wiper consists of three major components:

5-26
Figure 5-13.—Pendulum window wiper.

5-27
 1. Control box assembly (fig. 5-14). The control
box consists of the three-position wiper switch, the
wiper arm heater switch, a light to indicate when the
heater is energized, a variable powerstat for wiper
control, motor and system overload protectors, and a
full-wave bridge rectifier.
2. Drive unit (fig. 5-15). The drive unit consists of
a dc motor and a drive mechanism, which converts the
rotary motion of the drive motor to a back-and-forth
motion necessary for wiper operation.
3. Wiper arm. The wiper arm consists of upper and
lower arms and the wiper blade. The upper arm is a
stainless steel tube containing a 36-watt heating
element. The lower arm is 20 inches long and is bent
and cut during installation to suit the particular
installation. The wiper blade, attached to the lower arm,
Figure 5-15.—Drive unit.
is constructed of neoprene rubber and is used to clean
the window of water during operation.
the 40 to 1 reduction gear ratio, this means that the wiper
blade completes approximately 90 sweeps per minute at
OPERATION high speed. With the wiper switch in the ON position,
voltage to the motor is variable through the powerstat
Placing the wiper ON/OFF/PARK switch in the ON from 68 to 115 volts dc. With the switch in the PARK
position completes the circuit from the variable position, voltage is fixed at 40 volts dc.
powerstat, through the motor protector, to the bridge
Placing the wiper switch in the PARK position also
rectifier. The ac power is rectified and fed to the drive
motor through a fuse and a radio frequency filter. completes the circuit to the motor. When the switch is
released it springs back to the OFF position. This is
The motor speed (fig. 5-16) is adjusted through the convenient for placing the wiper blade out of view when
setting of the variable powerstat in the control box. At the window wiper is not is use.
full-load speed, the motor shaft turns at 3,600rpm. With
MAINTENANCE

Following prescribed preventive maintenance will

keep the window wiper operational for extended
periods. Refer to NAVSEA S9625-AF-MMA-010 for
procedures on adjusting the wiper blade alignment, the
travel, and the contact pressure.

SUMMARY

The pendulum window wiper is one of the simplest

pieces of equipment the EM will encounter. Since it is
needed when the weather is at its worst, good
maintenance procedures during good weather periods
will preclude having to work outside in the rain.

ULTRASONIC CLEANING MACHINE

Ultrasonic cleaners can be used to clean most items

that can be submerged in aqueous solutions. Besides
Figure 5-14.—Control box assembly. cleaning small parts, the cleaner is especially useful for

5-28
 Figure 5-16.—Window wiper schematic.

cleaning items with a mixture of dust, dirt, and grease, during the cleaning process, prolonging its life as a
such as vent filters. useful cleaning agent.

DESCRIPTION OPERATION

Ultrasonic cleaners use high-frequency vibrations

Single-phase, 450-volt, ac power is filtered and fed
in an aqueous solution to agitate and “scrub” particles
into a 2 to 1 step-down transformer. In addition to the
from an item to be cleaned.
generator cabinet blower, the cleaning solution
The tank of some ultrasonic cleaners is divided into circulating pump, and the heat exchanger, the secondary
two sections, allowing cleaning in one side and rinsing voltage of 220 volts is used to control the operation of
and drying in the other. Besides a tank for holding the a trigger circuit. The trigger causes pulses to be fed to
cleaning solution and the part to be cleaned, the cleaner an SCR in both generator circuits. The pulses to the
may also be fitted with a spray gun consisting of a hose SCRs cause the generators to develop a signal that is fed
and nozzle fitting to blast clean hard spots. The cleaning to the transducers. A frequency adjusting control on the
solution can be heated using a 5-Kilowatt electric heater trigger circuit permits adjusting the signal to the
for extra cleaning power. The cleaning solution is generators approximately ±1000 cycles on either side of
circulated through a filter to remove small impurities resonance for the transducers.

5-29
 Vibrations are generated in the ultrasonic cleaner dirt accumulations and the air filters in the generator
(fig. 5-17) by transducers. These transducers are compartment door should be cleaned or replaced
welded to plates, called diaphragms. When the periodical y according to PMS requirements. The
transducers arc energized, they produce extremely small generator fans and cleaner unit blower should be oiled
vibrations in the plates, 1 or 2 thousandths of an inch once a year and the water pump should be oiled every 6
(0.001 to 0.002 inch) but with strong accelerating forces. months.
As the plates vibrate, they cause whatever medium they
are suspended in to assume a similar frequency and SUMMARY
transmit that frequency throughout the vessel. The
plates are, in effect, a Hi-Fi speaker operating at one The ultrasonic cleaner is one of the most essential
frequency. machines on board when it comes to conducting repairs
When the medium through which the waves are to other pieces of machinery. Its ability to clean parts
transmitted is a liquid, there is good transmission and and some metallic ventilation filters makes it mandatory
very little loss of strength since all liquids are relatively that preventive maintenance procedures be strictly
incompressible. The physical shock of the vibrations on followed to ensure it stays operational.
the item being cleaned cause a “scrubbing” action much
better than a brush because the size of the sound waves ELECTROSTATIC VENT FOG
allows for cleaning of minute holes and crevices that PRECIPITATOR
would be impossible for a brush.
The electrostatic vent fog precipitator (fig. 5-18) is
MAINTENANCE mounted in the lube oil system of reduction gears for
main engines and generators. The purpose of the vent
The ultrasonic cleaner is extremely rugged and fog precipitator is to remove entrained oil mist from the
requires little maintenance other than cleaning and vented air of the reduction gears before it is discharged
oiling. The components should be kept free of dust and into the engine mom or space.

Figure 5-17.—Block diagram of ultrasonic cleaner.

5-30
 Figure 5-18.—Vent fog precipitator.

The oil mist is caused when the oil gets warm in the electrode. As the charged droplets progress up the
gear case and the air space of the entire lubricating collector tube, they are subjected to the electrostatic
system. The larger mist droplets will settle by gravity. field created between the high-voltage electrode and the
The fine mist will continue to rise, borne on air currents. grounded collector tube. Since their charge is of the
same polarity as the high-voltage tube, the force of the
The vent fog precipitator employs the basic
electrostatic field forces them to the wall of the collector
phenomenon of electrostatic precipitation. The fine oil
tube, which is of opposite polarity. Here the oil is
mist borne on air currents vented in confined areas of
collected and flows back to the machinery reservoir.
machinery will rise and enter the bottom end of the
The oil-free air continues up and is vented to the
collector tube through the flame arrester assembly. The
atmosphere.
droplets are instantly charged by a heavy ion
concentration emanating from the ionizer electrode The vent fog precipitator operates on 120-volt ac,
mounted on the end of the high-voltage repelling 60-hertz, single-phase power. The power pack is used

5-31
to convert the electrical power to high voltage 10,000 When the operating voltage drops below its minimum
volts dc. As you read this section refer to figure 5-19. requirement the lamp will go out.

The power pack and circuitry are shown in figure The access cover safety switch (13) is an interlock.
5-19. The circuit is a half-wave voltage doubler, With the cover removes the contacts are open and
consisting of a high-voltage transformer (1), two de-energize the primary of the power supply.
selenium rectifiers (9), and two capacitors (4 and 10). The components of the precipitator are the ionizer
The power supply assembly is the self-regulating type electrode (5) and the electrode chuck and high-voltage
commonly known as a constant-voltage transformer. tube (7). The assembly is held inside the collector tube
The resonating winding (X3-X4) connected to the (6) by an insulator. The insulator also serves to
resonatiing capacitor (2) serves to hold the power supply electrically insulate the high-voltage assembly.
voltage at a constant level when the primary input
voltage varies. The resonating circuit is designed to
SUMMARY
help limit the output power.

The high voltage from the power supply is The vent fog precipitator is a simple, rugged,
connected to a surge limiting resistor (8), which limits essential piece of equipment. By following posted
the current of an arc that might occur and provides maintenance procedures, it will remain a reliable,
protection for the capacitors. operational piece of equipment.
The negative output of the power supply is
connected to ground through a surge limiting resistor
(3). This resistor limits the feedback current due to an PROPULSION SHAFT
TORSIONOMETER
arc. It provides additional protection to the capacitors
through the ground terminal of the precipitator. The The propulsion shaft torsionometer is a device used
proper operation is indicated by a lamp (12) that is to measure the torque and (optionally) the rpm of a
connected to a resistor (11). A portion of the supply ship’s rotating propulsion shaft accurately. Of the types
output voltage is used for the neon indicating lamp. available in the fleet, the basic principles are the same.
By accurately measuring the torsional twisting of a
ship’s propulsion shaft, you can calculate the load
(torque) on the ship’s main engine. Using this figure,
the load on the shaft can be calculated into shaft
horsepower.

DESCRIPTION

Through the use of various sensors and components,

the shaft torsionometer detects the slight twisting and
(optionally) the rpm of the ship’s propulsion shaft. Then
the torsionometer produces a proportional signal and
uses the signal to drive appropriate indicators located
near the ship’s engineering console or on the bridge.
Shaft horsepower readings may also be displayed at
various remote locations, such as the pilothouse or the
chief engineer’s office, using repeaters or remote
displays.

The optional rpm system uses an rpm probe to

receive signals from a shaft mounted assembly. The
signals are then processed by the rpm conditioner and
sent through shipboard cables to the appropriate
Figure 5-19.—Vent fog precipitator wiring diagram. indicators.

5-32
MAINTENANCE The drum winch may have from one to four
horizontally mounted drums on which wire rope is
The components of the torque sensor system are wound for raising, lowering, or pulling loads. The drum
surprisingly rugged. Besides keeping the components winch may also include one of two gypsy heads. On
clean and dry, the only maintenance that should be newer winches with only one gypsy head, the gypsy
required from ship’s force personnel is preventive head can be removed and reassembled on the opposite
maintenance indicated in the ship’s PMS system. end of the drum shaft. Drum winches maybe driven by
electric motors (ac or dc), an electrohydraulic drive,
steam, air, a gasoline engine, or by hand.
SUMMARY
The gypsy winch has one or two horizontally
This section has introduced you to the operation of mounted gypsy heads around which several turns of line
the torsionometer. For a more detailed description of must be taken to prevent slippage when a load is snaked
the operation and construction of the system, refer to the or hoisted. Gypsy winches are driven by electric motors
manufacturer’s technical manual and NAVSEA (ac or dc), an electrohydraulic drive, steam, air, a
SN521-AC-MMM-010. gasoline engine, or by hand.
Winches on numerous auxiliary ships are often
referred to as deck winches or cargo winches.
DECK EQUIPMENT

A good deal of the electrician’s time aboard ship is ANCHOR WINDLASSES

spent performing maintenance. Of the items being
maintained, deck equipment receives the most wear and Anchor windlasses are installed on board ship
tear because of its intended use and location. Deck primarily for handling the chains used with anchors for
equipment must be in working condition for the ship to anchoring the ship. In addition, most windlasses are
be able to perform its assigned mission effectively. provided with capstans or gypsy heads for handling
lines and for mooring and warping operations. Anchor
windlasses can be of two types—electric or
WINCHES
electric-hydraulic.

Winches installed aboard ship are used to heave in

Electric Anchor Windlasses
on mooring lines, hoist boats, lift booms, and handle
cargo. Winches are classified by the drive unit and the
Electric windlasses are powered by an electric
type of design, either drum or gypsy. Figure 5-20 shows
motor that drives a wildcat(s) and head(s) directly
a simplified representative winch, which is a
through suitable reduction gearing. The electric power
combination of a drum and gypsy type of winch.
for the motor is either ac or dc.
Cargo ships, transports, and auxiliary ships are
generally provided with horizontal shaft, self-contained,
electric-driven windlasses with the motor and reduction
gearing located on the windlass bedplate on the open
deck. These windlasses have combined facilities for
anchor handling and warping. They consist of two
declutchable wildcats on the main shaft and two
warping heads on the shaft ends. These are driven
through suitable reduction gearing by the electric motor.
The motors are reversible, variable speed. They are
provided with magnetic brakes to hold the load if the
power fails or under service conditions. Their dual
magnetic controls provide both straight reversing
characteristics for warping and dynamic lowering
characteristics for anchor handling. Transfer switches
allow selection of the proper characteristics. When used
Figure 5-20.—A simplified representative winch. for anchor handling, the control usually provides five

5-33
speeds in each direction with adequate torque in hoist Destroyer Anchor Windlass
directions and dynamic braking in all lowering points.
For warping, the control characteristics are substantially The anchor windlass installed aboard destroyers
identical in both directions. A single controller master consists of a two-speed motor directly connected
switch is provided and located on the deck adjacent to through reduction gears to a vertical shaft. A capstan
the windlass. and a wildcat (fig. 5-21) are mounted on the vertical
shaft. The capstan and the wildcat are located on the
Electric-Hydraulic Anchor Windlasses weather deck; the electric motor and the across-the-line
starter are located in the windlass room on the next deck
Electric-hydraulic anchor windlasses are below. The windlass is designed to operate in both
particularly adapted for anchor handling because of directions to raise or lower either the starboard or port
varying load conditions and their wide range of speed anchor.
and torque characteristics. The hydraulic drive was
developed to overcome all the operating and installation CONSTRUCTION.— The windlass is driven by a
objections inherent with either steam- or two-speed (full speed and one-quarter speed),
direct-electric-driven windlasses. The electric- three-phase, 440-volt, 60-hertz motor connected to the
hydraulic windlass drive is similar to the electric drive reduction gear by a controlled torque coupling. The
with one exception. Instead of having the electric motor controlled torque coupling is provided to prevent undue
coupled directly to the reduction gearing, the power is stresses when the anchor is being housed. When the
transmitted from the electric motor through a variable anchor is housed, the drum master switch must be
stroke hydraulic transmission. This obtains a wide shifted to the low-speed position before the anchor
range of output shaft speed. enters the hawsepipe.

The electric motor for a hydraulic windlass is An electric brake is mounted just below the
usually a single-speed, squirrel-cage type. Electric controlled-torque coupling. This brake will release
control is required only for light starting duty, as the when power is applied. It will set when power is
motor is started in a no-load condition. The motor is disconnected or fails. If power fails, the electric brake
direct coupled to the pump unit of the hydraulic motor is designed to stop and hold 150 percent of the rated load
unit, B-end, through piping. The B-end is coupled to a when the anchor and chain are being lowered at
suitable reduction gear that drives the windlass shaft. To maximum lowering speed.
determine windlass speed, you vary the stroke of the The wildcat is designed to hoist one anchor and 60
pump A-end. This is done by control handwheels, fathoms of 1 1/4-inch dielock chain in not more than 10
located on the weather deck and at the pump. These minutes on the high-speed connection without
handwheels also control the direction of rotation of the exceeding the full-load rating of the motor. On the
windlass and are suitably marked. The stroke at which low-speed connection, the wildcat is designed to hoist
the A-end is set determines the quantity of hydraulic
the anchor and 60 fathoms of chain without overloading
fluid delivered to the B-end, which, in turn, determines the motor. Also, on the low-speed connection, the
the speed at which the B-end rotates. wildcat exerts a pull on the chain at least three times that
The power plant of a typical hydraulic windlass required to hoist the anchor and 60 fathoms of chain.
installation for large combatant or auxiliary vessels has
The capstan is designed to heave a 6-inch
two units. Each unit comprises a constant-speed,
circumference manila line at a speed of 50 feet per
horizontal, squirrel-cage, electric motor driving a
minute with a line pull corresponding to the full-load
variable stroke hydraulic pump through suitable
motor torque.
reduction gearing. The electric motors have magnetic
brakes designed to hold 150 percent of the motor-rated The capstan head is keyed directly to the drive shaft,
torque. They are set on loss of power to prevent the while the wildcat is connected to the drive shaft through
anchor dropping. The power units are arranged, port a driving head and a locking head. The wildcat is keyed
and starboard, in the windlass room. Normally the port to the driving head, and the locking head is keyed to the
unit drives the port windlass half, and the starboard unit, drive shaft. Vertical blocks sliding in slots in the locking
the starboard half. However, transfer valves are head are raised (by the locking handwheel) into slots in
provided in the oil lines that, when properly set, allow the driving head to connect the two heads. The
the port power unit to operate the starboard windlass, mechanism is called the locking gear. The wildcat and
and vice versa. sleeve run free on the same shaft until connected to the

5-34
 Figure 5-21.—Anchor windlass.

shaft by a locking head located below the weather deck. revolve. In this case, if the chain is engaged in the
You can run the capstan independently for warping by whelps on the wildcat, the chain should be free to run.
disconnecting the locking head and holding the wildcat Be careful to select the proper direction of rotation and
by the brake band on the brake drum. You can pin the be sure that the windlass is properly lubricated.
handwheel in the LOCKED or UNLOCKED positions. You can operate the motor from either master switch
Ensure it is always fully locked or fully unlocked to No. 1 (on the weather deck) or from master switch No.
prevent unnecessary wear on the brake. 2 (in the windlass room). Master switch No. 1
There is a hand brake on the wildcat shaft to control predominates. When the associated on-off switch
the anchor handling. It is designed to operate in either located on master switch No. 1 is operated in the ON
direction of rotation of the wildcat and to stop and hold position, master switch No. 1 takes over the control from
the anchor when dropped into a depth of 45 to 60 master switch No. 2 (if both switches are operated
fathoms. The brake is operated by a handwheel located simultaneously).
on the weather deck or by a duplicate handwheel in the
The anchor windlass is used alternately to handle
windlass room.
either the starboard or the port anchors. The windlass
OPERATION.— The windlass is operated by a is operated by a reversible motor in either of two
drum master switch on the weather deck and a duplicate directions. These directions may be hoist for the
switch in the windlass room. It is important to starboard anchor (lower for the port anchor) and hoist
remember that if the windlass is run with the locking for the port anchor (lower for the starboard anchor).
handwheel in the LOCKED position, the wildcat will However, only one anchor can be handled at a time.

5-35
Figure 5-22.—Reversing across-the-line starter for a two-speed anchor windlass.

5-36
 The motor starter (fig. 5-22) is equipped with four EMERG-RUN push buttons down and operating the
thermal overload relays to protect the motor against master switch in the usual manner. To reset the overload
overloads. Overload relays 1FOL and 2FOL are in the relays, press the OVERLOAD RESET push buttons if
fast-speed motor circuit. If an overload occurs in the an overload or voltage failure occurs. Return the master
slow-speed or fast-speed circuit, the SOL or the FOL switch to the OFF position to restart the motor.
relays will operate to trip the slow-speed or the To start the motor in the port (hoist) direction for
fast-speed contractors, respectively. You can operate the slow speed using master switch No. 1, take the following
motor in an emergency by holding either of the actions:

5-37
 The motor is now connected for hoisting the port If you operate the motor by master switch No. 2,
anchor at slow speed. operate the associated ON-OFF switch to the ON
position and move the controller handle to the PORT or
When the controller handle is moved further to the
STARBOARD SLOW position. This action closes
FAST-PORT position:
contacts MS21 momentarily y to energize the operating
coil of relay CR2 (if relay CR1 is not energized). The
sequence of operation for master switch No. 2 is almost
the same as that for master switch No. 1. However,
contractors P, ST, S, and Fare energized through the CR2
contacts instead of through the CR1 contacts. You can
lock out master switch No. 1 by turning the selector
switch to the No. 1 LOCKED position. In this position
the selector switch opens the circuit to relay CR1 and
prevents its operation.

Operating instructions and system diagrams are

normally posted near the anchor windlass controls. The
diagrams describe the various procedures and
lineups.

MAINTENANCE.— General maintenance of

anchor windlasses should follow the PMS installed
aboard ship.

SUMMARY

The information covered on winches and

windlasses is only an introduction. More information
on the specific type and size of equipment aboard your
ship is available in the manufacturer’s technical manuals
and NSTMs available in your technical library or
legroom.

ELEVATORS
The motor is now connected for hoisting the port
The elevator installations aboard aircraft carriers
anchor at fast speed. The same sequence occurs to hoist
usually consist of hydraulic or electric types for airplane
the starboard anchor. However, controller contacts
elevators and electrohydraulic or electromechanical
MS13 energize the operating coil sr to close the
types for freight, mine, bomb, torpedo, and ammunition
starboard contactor instead of controller contacts
elevators. This section contains a discussion about the
MS12 energizing the operating coil to close the port
electric and electrohydraulic elevators and the
contactor. electronic control system of some elevators.

5-38
ELECTRIC (ELECTROMECHANICAL) • Emergency stop switches at each level served.
ELEVATORS These switches allow operators at any level to
stop the elevator should a malfunction occur.
The platform on electric elevators is raised and
• Overtravel switches. These switches stop the
lowered by groups of cables that pass over sheaves and
elevator if it should fail to stop at the uppermost
then to the hoisting machinery drums. The hoisting
level.
drums, coupled together, are driven through a reduction
gear unit by an electric motor. • Overload protection. This feature prevents
damage to the system from an overload
The motor is of the two-speed type. The control
arrangements are such that the elevator starts and runs condition.
on the high-speed connection. The low speed is used
for deceleration as the elevator approaches the upper or
Elevator controllers are designed with a
lower limit of travel.
double-break feature that prevents improper operation
The two-speed electric motor is controlled through if any one contactor, relay, or switch should fail to
a system of contractors, relays, limit switches, and function properly. Pushbuttons are interlocked to
selector switches. Automatic operation is obtained by
prevent operation of the elevator unless the platform is
selecting the levels between which the platform is to run.
at the same level as the pushbutton. Some elevators are
The start pushbutton can then be used to close contractors
equipped with hatchway door mechanical interlocks to
through safety switches to operate the elevator at high
prevent opening the door unless the platform is at the
speed. Just before reaching the desired level, the control
transfers the motor to the low-speed winding through same level.
the action of cam-operated limit switches. On reaching A governor-actuated safety device is provided
the desired level, the control circuit is disconnected by
under the platform to grip the guide rails and stop the
a cam-operated stop switch, releasing the contractors and
platform if there is an overspeed in the DOWN
setting the brake to stop the platform.
direction. Also, spring bumpers are provided at the
bottom of the hatchway to prevent mechanical damage
to the hull or platform due to overtravel in the DOWN
For safety in operation, all doors at each direction.
level are interlocked to prevent operation
The operation of the elevator depends on the
unless they are closed. Also, all hatch covers
position of the selector switch. The selector switch
are interlocked to prevent elevator operation
unless they are fully opened. determines which decks the elevator will run
between. This switch also makes all master switches
inoperative, except those pertaining to the selected
The following protective features are incorporated levels.
in the control:
Suppose the selector switch is set in the second
• Slack-cable switches. These switches prevent platform to the third deck position (fig. 5-23). Refer to
operation of the elevator if any cable should figure 5-23 as you read the sequence of events which
become slack. follow:

5-39
5-40
Figure 5-23.—Schematic diagram of electric elevator automatic control selective from one station.

5-41
 As already mentioned, additional protection is ELECTROHYDRAULIC ELEVATOR
provided through a system of series-connected
interlocks in the control circuit. These interlocks consist The electrohydraulic elevators use hoisting cables
of door, slack cable, and overtravel switches. The and drums in much the same manner as the electric
following table lists some of the means of elevator elevator. In this system, however, the cable drums are
operation during malfunctions: driven through reduction gears by a hydraulic motor.
Raising, lowering, or speed changes are accomplished
by varying the stroke of the variable delivery hydraulic
pump through differential gearing. Figure 5-24 shows
a typical arrangement scheme for operation of the
electrohydraulic bomb elevators.
The elevators use a follow-up type control system
so that the pump is put on stroke by a pilot motor and
the stroke is taken off by the motion of the platform
working on the follow-up control.
On some elevators, the pilot motor is started by
depressing an operating pushbutton. The pilot motor
moves the pump control piston to the ON-STROKE
position, and the elevator accelerates to full speed.
Upon approaching the selected level, a platform
mounted cam trips a slow-down switch that
de-energizes the pilot motor. Movement of the platform
then returns the stroke of the pump to the NEUTRAL
position. On reaching the selected level, a stop switch
de-energizes the brake solenoid to set the brake and stop

Figure 5-24.—Bomb elevator power plant and control scheme.

5-42
the elevator. Reversing the direction of rotation of the ELECTRONIC CONTROLLED
pilot motor reverses the direction of movement of the ELEVATORS
control piston of the pump. This allows the elevator to
be moved in the opposite direction.
Elevators installed on some new naval ships use
In another electric-hydraulic system, the pilot motor static controls (no meting parts). In these elevators,
is a dc motor. The speed of the motor is varied by a electronic devices perform the functions of relays,
rheostat-type control that gives an infinite number of contractors, and limit switches.
platform speeds. These speeds range from
approximately 3 to 90 feet per minute. In installations The electronic controlled elevator system
of this type, a rheostat control is provided on the components (fig. 5-25) include the elevator cam target,
platform, and a duplicate control is provided in the the sensing heads, the static logic panels, the motor
elevator machinery room. (magnetic) controller, and a three-phase drive motor.
These system components function as follows:
Several methods are used for stroking the pump for
emergency operation two of which are as follows: The elevator cam targets are steel cams or vanes,
mounted on the elevator platform to actuate the sensing
1. Declutching the “follow-up” control system
heads.
from the control stroking unit and manually holding in
a pushbutton. This action releases the electric motor The sensing heads are mounted up and down
brake to free the machinery. A handwheel maybe used the elevator trunk bulkhead. They are used for
to stroke the pump. many elevator functions, such as slowing and
2. Rotate the pilot motor armature by attaching a stopping, high-speed up and down stops, governing
handwheel to an extension on the armature shaft, thus overspeed, preventing overtravel, and door interlock
stroking the pump. functions.

Figure 5-25.—Block diagram of electronic controlled elevator system.

5-43
 The static logic panel is a solid-state, low-power The three-phase, 400-volt, 60-hertz motor drives
system that performs functions normally associated. the elevator
with limit switches, relays, and contactors (fig. 5-26).
The logic modules consist of proximity switches, signal PROXIMITY LIMIT SWITCHES
converters, retentive memories, reset memories, shift
registers, duo-delay timers, and pulses with Proximity limit switches (electronic limit switches)
appropriate logic elements and circuitry. are used extensively to control elevator movement.
Basically, the proximity switch consists of a remotely
The motor controller (fig. 5-27) energizes located sensing head and a logic module that amplifies
appropriate contractors to control the speed and the sensing head voltage to a positive 10-volt level used
rotation of the motor.

Figure 5-26.—A static logic panel at the sixth level for a cargo elevator.

5-44
Figure 5-27.—AC magnetic reversing controller for a two-speed, two-winding motor for a cargo elevator.

by the static logic control system. The voltage output is sensing zone to create a signal. The signal strength
+10 volts when the cam target on the elevator car is depends primarily on the distance between the face of
moved in front of the sensing head mounted on the the sensing head and the target.
elevator shaft. The voltage output is zero when the cam
Operation of a proximity limit switch maybe best
is moved away from the sensing head (deactuated). The explained by examining the following basic circuits and
metallic elevator target to be sensed must enter the components:

5-45
 The power supply (fig. 5-28), consisting of the Schmitt-Trigger
115/15 volt transformer, D1, D2, C1, R1, and R2.
The Schmitt-trigger, consisting of Q4 and Q5,
The voltage across D2 used to bias the succeeding
presents a voltage across R23, which is used to bias the
amplifier stages.
output switch transistor Q6 to its ON a OFF state.
The Zener diode (D2) has a breakdown voltage of
12 volts, which protects the following stages from Output Switch
overvoltage.
The proximity switch supplies only the switching
power. Proximity limit switch terminals 6 and 8 connect
Sensing Heads
to a 10-Volt, dc static logic power source. This power
source is supplied at terminals 7 and 8 and the proximity
The sensing heads (fig. 5-28) consist of two coils light is lit when Q6 switches to the ON state.
connected in series opposition, which, when energized
by mutual inductance from a third coil, are balanced by When the target is in the sensing zone, the sensing
means of a tuning slug. A resistor, connected in parallel head has an output that is amplified rectified, and
with the top sensing coil, is used for positioning the filtered, switching the output of the Schmitt-trigger off.
sensing heads. An output voltage is produced by the This turns the output switch Q6 (fig. 5-28) to its ON
sensing head when an elevator cam target enters the position. Therefore, when the target is in the sensing
field, resulting in an output to terminals 3 and 5. zone, there is an output and the status light L1 is on.

MAINTENANCE
AC Amplifier

As with all electrical and electronic equipment,

The input to the ac amplifier is supplied by the
preventive maintenance must be performed on a routine
sensing head at terminals 3 and 5 (fig. 5-28). The
basis and according to the PMS and the manufacturer’s
sensing head signal is amplified by three cascaded
instruction manuals. Good housekeeping practices and
amplifier stages consisting of Q1, Q2, and Q3 with
routine adjustments play an important part in the
suitable biasing networks. The amplifier output is fed
maintenance of elevator controllers.
through a rectifier consisting of D3, D4, D5, and D6.
This signal is filtered by the RC network of C11 and R18 Pay special attention to the proximity switches. Do
to drive the following Schmitt-trigger. not test the control circuitry with a megger because the

Figure 5-28.—Schematic diagram of a proximity limit switch.

5-46
high voltage generated by a megger can easily damage Drop-out voltage cannot be adjusted and depends
electronic components. If a proximity switch doesn’t on the tolerance of resistors in the Schmitt-trigger
pick up or drop out properly, make the following checks circuit. If drop-out voltage is not within tolerance,
on the amplifier at the panel: check the values of resistors R19 through R23.

1. Check the indicating lamp for operation If the above checks and adjustments do not correct
the trouble, the problem must be internal to the
2. Measure voltage and frequency input and output
amplifier. In this case, the amplifier should be removed
at the T1 transformer (take all measurements
from the panel for servicing.
with high impedance meters greater than 1
megohm). SUMMARY
3. Measure drop-out voltages between terminals Elevators have become one of the mainstays of
#3 and #5 of the proximity switch (with and equipment aboard ship. While they present a great
without the cam target at the pick-up point). See convenience when moving stores and equipment, they
the manufacturer’s manual for proper tolerance are also one of the most hazardous pieces of gear to
values. operate. When dealing with the elevators aboard ship,
IF any of the above measurements are out of you should be sure safety is always the number one
tolerance, you should first check for metal, other than priority. Sailors and shipyard workers are killed almost
every year due to improper work and maintenance
the metal target in the sensing field
practices. Refer to the applicable technical manuals and
The null point of the sensing head may need training material aboard ship for safety precautions to
adjusting. To adjust the null point, remove the soft plug be observed when operating or maintaining the
in the tuning slug hole of the sensing head and turning elevators aboard your ship.
the slug with an Allen wrench. Remove the wrench
when checking the null point.
UNDERWAY REPLENISHMENT
The amplifier sensitivity is adjusted by removing SYSTEM
the plug button on the top right of the amplifier and
adjusting the potentiometer (Pi) screw. Be careful when The underway replenishment (UNREP) system is a
inserting the screwdriver. Clockwise rotation reduces high-speed, heavy weather, day or night method of
pick-up voltage, while counterclockwise rotation will transferring missiles and other loads between a
increase the pick-up voltage. This adjustment is very noncombatant supply ship and a combatant ship while
sensitive and must be executed cautiously. underway. The system shown in figure 5-29 is made up

Figure 5-29.—UNREP system.

5-47
of two major units-the SENDING UNIT, located on Centerline Elevators
the delivery ship, and the RECEIVING UNIT, located
on the receiving ship. The centerline elevators are used in the system to
In operation, the sending and receiving units are move missiles from the lower deck storage to the second
connected through a ram tensioner by a l-inch-diameter deck. When missiles are stored at the second deck
wire rope (highline) to form an integral system. A fast instead of a lower level, the centerline elevator is not
trolley is pulled back and forth along the highline used. The second deck has the overhead hi-rail tracks
between the ships by the electrohydraulic, and necessary equipment for delivery of the missile to
winch-tensioned inhaul and outhaul lines. These lines topside. A strongback is manually connected to the
are supplied by the delivery ship. The receiving unit can missile when it reaches the second deck to facilitate the
function to return missiles or other loads back to the careful handling of the missile, as it moves through the
supply ship. system.

Since it is not possible to cover all types of UNREP Bridge Crane

systems, the ammunition ship (AE) UNREP system is
used as a representative system for explanation The bridge crane moves the hi-rail hoist into the
purposes. centerline elevator. Here, the hi-rail hoist mates with
the strongback and lifts the missile from its storage
cradle to a LOCK-ON position on the hi-rail hoist. The
DELIVERY SHIP bridge crane then pulls the hi-rail hoist from the elevator
area to the hi-rail track.
The delivery (supply) ship has the missiles racked
below deck with the necessary facilities to deliver a Bi-rail Hoist
missile to the receiving ship. Figure 5-30 shows an AE
UNREP delivery system with the steps the missile goes The bi-rail hoist is an air-driven car that rolls along
through during the move and the names of the an overhead track on the second deck. The hi-rail hoist
equipment that moves the missile. transports the missile to the component lift.

Figure 5-30.—UNREP system equipment used to move a missile from storage to the receiving ship.

5-48
 The bi-rail hoist lowers a spider to mate with the highline (fig. 5-31). The highline is tensioned at 18,000
strongback that raises the missile from the centerline to 20,000 pounds during ship-to-ship replenishment
elevator. After the strongback is raised and secured to operations to hold the weight of a load of about 5,000
the hi-rail hoist, the hoist is moved to align with the
pounds. The highline stays tensioned even when the
hi-rail tracks. At this point the bi-rail hoist can turn the
missile around (180°), if necessary. The need for distance between the two ships changes and when the
turning the missile depends on the receiver ship’s ships roll toward or away from each other.
strikedown equipment. The highline winch (fig. 5-31) has a
200-horsepower electric motor. The motor operates at
Component Lift
440-volt, three-phase, 60-hertz power, and 180 amperes
When the hi-rail hoist has the missile centered over when working at a full load.
the component lift, the component lift arms swing out
A hydraulically operated antibirdcager is installed
and mates with the strongback. The bi-rail hoist
unlatches and returns for the next missile. The to keep the wire rope from tangling during operation of
component lift raises through the hatch to the main deck the UNREP winches. This unit keeps a steady tension
and onto the transfer head where the strongback is then on the wire rope at the winches.
connected to the trolley for transporting. The
abovedeck equipment on the delivery ship is comprised The ram tensioner (fig. 5-31) is a unit that helps the
of a kingpost, a transfer head, a tensioned highline, and highline winch operator keep the highline tight. When
the ram tensioner. the ram tensioner cannot haul in or pay out the
highline fast enough to keep the correct tension, the
Highline Winch and Ram Tensioner
highline winch operator hauls in or pays out the
The trolley travels between the delivery and the highline to help the ram tensioner maintain the correct
receiving ship on a tensioned wire rope, called the tension.

Figure 5-31.—Highline winch.

5-49
Inhaul and Outhaul Winches receiving head On the other head are shock absorbers
(called jackknifes) that slow the trolley and arms that
Wire ropes from two winches (figs. 5-32 and 5-33) steady it while the missile is being removed by the
control the missile transfer during ship-to-ship transfer elevator.
operation. The outhaul winch pulls the trolley, which is
holding the missile and riding on the tensioned (outhaul) The elevator takes the strongback and load from the
highline to the receiving ship. After the missile has been trolley and deposits them on the strikdown elevator.
delivered, the inhaul winch returns the empty trolley by Lateral orientation of the elevator arms is controlled by
pulling it back to the delivery ship with a wire rope. the swing of the receiving head. Regardless of roll,
The highline winch and the inhaul/outhaul winches pitch, height of the load and station alignment, the arms
(figs. 5-31 and 5-32) all have the same electrical, assume the correct position to receive the strongback
mechanical, and hydraulic system. The electric motors supporting the load. A quick-acting mechanism in the
on the winches drive three pumps—the servo pump, the trolley (called pick-off probes ) releases the strongback
main pump, and the makeup pump. when the elevator arms are fully closed and locked in
slots in the strongback.
RECEIVING SHIP
The UNREP gear varies from ship to ship. For
The UNREP receiving (combatant) ship receives example, one type may be stationary, while another must
the missile with the receiving unit (fig. 5-34). The be stowed like a crane boom to keep it from interfering
receiving unit consists of a kingpost, a receiving head,
with the ship’s armament. One type will service only
an elevator, a carriage return hydraulic power unit, and
one strikedown elevator, whereas another may have the
a remote control console. The receiving head is
supported by the kingpost, and the elevator operates capability of swinging around to service both port and
vertically on the kingpost. The trolley is captured by the starboard elevators.

Figure 5-32.—Parts of the inhaul/outhaul winch.

5-50
Figure 5-33.—Top view of AE UNREP system (view looking aft).

5-51
Figure 5-34.—Reciving unit.

5-52
 The specific operations of the elevator are 5. Operating the transfer signal holdup light
controlled by the console operator by pushbutton An ultraviolet night-light is installed above the
switches on the remote control console. console to illuminate the switch panel during night
operations. When not in use, the control console is
Remote Control Console stowed within the console stowage box.

Elevator Drive Control System

The electrical system provides the controls and
signals necessary to operate the receiving unit from a
The elevator drive control system raises and lowers
remote control console. Figure 5-34 shows the control
the elevator. The elevator mechanism is supported by
console mounted on a pedestal near the receiving unit.
the kingpost. A chain hoist, located within the kingpost,
The control console is a portable aluminum box housing
is attached to the elevator and is driven by a bidirectional
with control switches and indicator lights installed. The
electric motor for elevator operation. The motor is
switches on the console are grouped by their control
mounted on the side of the kingpost near the base (fig.
function (fig. 5-35). The power switch is in the upper
5-34). The 5-horsepower motor operates on 440-volt
right-hand corner of the control console and connects
ac, three-phase, 60-hertz power at 1,800 rpm. It is a
and disconnects the 440-volt, ac ship’s power supply to
watertight motor and drives the elevator through a worm
all the electrical components of the receiving unit. The
gear type of speed reducer. A solenoid-operated disk
main electrical operations of the receiving unit are as
brake, installed on top of the elevator drive motor,
follows:
performs fast action in stopping and starting the motor.
1. Raising and lowering the elevator This permits the swift and accurate positioning required
by the system. The operator at the console can stop the
2. Opening and closing the elevator arms elevator at any position along the kingpost.
3. Immobilizing the meeting carriage when Electrical circuits provide the means to raise the
receiving and stowing the missile elevator with the arms open and unloaded or with the
4. Releasing the trolley latch arms closed and loaded. These circuits also allow

Figure 5-35.—Control console on a receiving ship.

5-53
lowering if the elevator with the arms open and unloaded mechanically operates an electrical limit switch. This
or with the arms closed and loaded Emergency circuits action automatically energizes the carriage return
bypass the normal control switches to provide a built-in solenoid valve (fig. 5-36, view B) and allows the
safety for emergency operation. They should never be hydraulic fluid within the carriage return cylinder to
used unless an emergency arises. bleed off into the reservoir (fig. 5-36, view A). As the
trolley moves all the way into the receiving head, the
ARMS ROTATION CONTROL SYSTEM.—
meeting carriage is pushed back into the INDEXED
The arms rotation control system controls the opening
position and the cylinder is collapsed. When the
and closing of the elevator arms for both normal and
meeting carriage solenoid valve is de-energized, the
emergency operations. The arms system consists of an
supply port to the cylinder is open, and hydraulic
electric motor (fig. 5-34), a speed reduction gearbox,
pressure pushes the meeting carriage into the
and a cross-shaft, worm gear mechanism. The
RECEIVED position. Upon trolley release, the
1 1/2-horsepower electric motor is bidirectional and is
jackknife and limit switch also return to their normal
watertight. It operates on 440-volt ac, three-phase,
operating positions.
60-hertz power at 1,800 rpm. The components, as a unit
and with the necessary control circuitry, function to An electric motor mounted vertically on top of the
open and close the arms of the elevator. reservoir (fig. 5-36, view A) operates a positive
displacement gear type of hydraulic pump located inside
MEETING CARRIAGE CONTROL the reservoir, The motor is a three-phase, 440-volt ac,
SYSTEM.— The meeting carriage (fig. 5-34) receives 60-hertz, waterproof motor with a rating of 1 1/2
and cushions the incoming missile with the trolley horsepower at 3,600 rpm. Operation of the hydraulic
catcher and jackknife units. The meeting carriage is pump motor is automatic and maintains the hydraulic
pushed back horizontal y about 20 inches, moving from fluid supply pressure at about 1,000 psi. During
the fully extended RECEIVED position to the fully operation, whenever the supply pressure within the
compressed INDEXED position. The carriage is held accumulator is below 950 psi, the oil pressure switch
in the INDEXED position by the trolley, which is (fig. 5-36, view A) will close electrical contacts and start
retained by the trolley latch When the trolley latch is the pump motor operating. As the pressure inside the
released the trolley is pulled from the receiving head. accumulator reaches 1,000 psi, the oil pressure switch
Hydraulic pressure is automatically supplied to the electrical contacts open and stop the motor. The console
carriage return cylinder, which extends the cylinder and operator can override the automatic controls at anytime.
moves the meeting carriage to the RECEIVED position.
TROLLEY LATCH RELEASE.— The trolley
During operation when the trolley enters the latch (fig. 5-34) consists primarily of a latch pin and
receiving head, the jackknife folds back and trunnion assembly, a locking arm, a solenoid, two limit

Figure 5-36.—Carriage return hydraulic power unit: A. Back of unit: B. Front of unit.

5-54
switches, and a manually operated release lever. The of the types of UNREP equipment you will encounter.
latch will automatically fall into the latch hole in the side Since there are so many pieces of equipment and the
of the trolley when the trolley has been pulled into the amount of maintenance needed to keep it functional is
receiving head enough to push the meeting carriage into so great, most ships have EMs dedicated to the deck
the INDEXED position. department to devote the needed time to the equipment.
The trolley latch release system has a blue signal
light (not shown) located on the opposite side of the
ELECTRIC FORKLIFT TRUCK
receiving head unit and a blue indicator light lusted at
the control console (fig. 5-35). The purpose of the Electric forklift trucks are primarily used for
electrical circuit is to provide the winch operator on the handling, transporting, and warehousing materials in
supply ship and the console operator on the receiving confined areas where engine exhaust times cannot be
ship with a visual indication that the trolley is latched. tolerated. Figure 5-37 shows two of the electric forklifts
When the trolley is latched the blue trolley latched most commonly used. The larger vehicles are electric
lights are illuminated and are extinguished when the powered, front-wheel drive, rear-wheel power-steering
trolley is released.
The trolley latch signal light circuit receives
110-volt ac power from the 440/120-volt transformer.
The 440-volt ac power to the transformer is controlled
by the power switch located on the control console.

The operator can manually control the automatic

trolley latch system. The operator does this by releasing
the latch. The latch can be released in two ways-by
energizing the trolley release solenoid from the control
console or by manually pulling the release handle on the
side of the kingpost.

Transfer Signal Holdup Light

The transfer signal holdup light circuit has an amber

signal (fig. 5-34) located on the receiving head unit. An
amber indication light is located on the control console.
The purpose of the electrical circuit is to give the winch
operator on the supply ship and the console operator on
the receiving ship a visual indication when the ships are
becoming too far off station. Whenever the receiving
head trains more than 30 degrees off station, the lights
are illuminated This light circuit also lets the console
operator signal the winch operator to temporarily y stop
operation.
The holdup transfer signal light circuit receives
120-volt ac power from the 440/120-volt transformer.
The 440-volt ac power to the transformer is controlled
by the power switch located on the control console.

SUMMARY

The UNREP system is a complicated system

consisting of many components working together to
perform an important function at sea. While the
information given above may not match all the types of
Figure 5-37.—Electric forklift trucks.
equipment found aboard your ship, it is representative

5-55
forklift trucks (fig. 5-37, view A). Figure 5-37, view B, power to the drive motor over a given period of time.
shows a smaller electric forklift that has both steering Most forklifts have speed controls that are incremental
and drive provided by the rear wheels. A 36- or 24-volt type of controllers. In incremental controllers, a bank
storage battery is required to furnish power for the of resistors is inserted into or shorted out of the circuit
traveling, the lifting, and the steering mechanism. to obtain speed control. The stepless type in the newest
The drive mechanism includes an electric drive forklift trucks uses SCR control circuitry. The
(traaction) motor, coupling, power axle assembly, and incremental type of truck control is similar to a car with
control. Control of the travel circuit provides one a standard shift, and the stepless type of control is similar
automatic accelerating speed plus four forward and four to a car with an automatic transmission that provides for
reverse controlled speeds. smooth control of the speed.

The lifting mechanism includes an electric motor, Many of today’s shipboard requirements for
hydraulic pump, hydraulic fluid reservoir, hoist, tilt, side material-handling operations necessitate very smooth
shift cylinders, directional control valve, forks, and acceleration of the electric truck. Smooth acceleration
controls. for a major portion of the speed range is highly desirable
and permits accurate maneuvering of the truck for
The vehicle steering system consists of a steering
spotting loads in congested areas.
motor, pump, steering gear assembly, power steering
unit, trailing axle, and controls. The electrical system of an electric forklift maybe
logically divided into a power circuit and a control
The brake system consists of a master cylinder,
circuit. These two circuits comprise the circuitry for the
mechanical parking brake, and hydraulic service brakes.
hydraulic pump motor, the steer motor, and the drive
The operator controls the truck speed by depressing motor. Figure 5-38 shows the wiring diagram of an
the accelerator pedal, which determines the amount of electric forklift. Please refer to this figure as you read

Figure 5-38.—Wiring diagram of an electric forklift.

5-56
about the operation of the pump motor, the steer motor, • The static timer. Provides an adjustable time
and the drive motor and controller. delay between first and second speed, and one
between second and third speed, as well as a fixed
PUMP MOTOR time delay between third and fourth speed.
• The brake switch Operated by the brake pedal,
The hydraulic-lift pump motor power circuit
interrupts the drive control circuit whenever the
consists of the pump motor and contacts of the pump
brake pedal is depressed It also provides power
relay coil P. The pump motor control circuit consists of
for starting on a grade by the antirollback (ARB)
the pump relay coil P and lever valve switches that are
connection of the static timer.
actuated by a hydraulic control valve.
• The static timer. Provides for controlled
To operate the lift system of the truck, you must
plugging.
close the battery switch and turn on the key switch. The
movement of one of the lever valve switches starts the • The control fuses (not shown). Protects the drive
hydraulic-lift pump motor. When the levers are motor and the static timer against electrical
returned to neutral, the pump motor stops. faults.
• The thermal switches (not shown). Opens the
STEER MOTOR
drive and steer motor circuits in case motor frame
temperatures reach 225°F.
The steer motor power circuit consists of the steer
motor and contacts of the steer relay coil S. The steer The master accelerating switch used for controlling
motor control circuit has a relay coil S and, on the truck speed is a manually operated pilot device to
seated-type forklifts, a steer switch that is closed when control magnetic contractors. These magnetic
the operator is seated. On this type of forklift the motor contractors control the drive motor of the vehicle. An
is in continuous operation while the operator is seated. OFF position and four speeds are provided. The switch
This permits power steering even though the truck is not is operated by an accelerator pedal.
moving. The directional master switch determines the
direction the vehicle operates. The switch is a
DRIVE MOTOR AND CONTROLLER three-position, manually operated, two-circuit pilot
device. It is designed for handling coil circuits of
The drive motor controller regulates the speed of the directional magnetic contractors that must be energized
series drive motor by solid-state control circuitry to initiate movement of the truck.
integrated with magnetically operated devices. This
The heart of a solid-state speed control system is the
circuitry enables the generator to handle heavy loads at
SCR. Essentially, the SCR is nothing but a rectifier,
low speeds with very little battery current. This results
except that a control element (commonly referred to as
in extra hours of operation. For full-speed cruising, the
agate) has been introduced. As applied in stepless truck
solid-state system is removed from the control circuit.
control systems, the SCR is nothing but a switch.
This connects the drive motor across the battery supply.

The drive motor power circuit (fig. 5-38) consists As you read about the sequence that takes place in
of the drive motor with its series fields; speed-changing normal operation when the directional control handle is
moved to forward or reverse and the accelerator pedal
relay contacts 1A, 2A, 3A, and 4A; and the forward and
is slowly depressed, refer to figure 5-38 and table 5-4.
reversing relay contacts F and R. The functions of the
components in the drive motor control circuit are as Table 5-4.—Drive Motor Field Connections
follows:

• The accelerator pedal switches. Provides the

four accelerating speeds by controlling the series
fields of the drive motor.
• The speed-changing power relay coils (1A, 2A,
3A, and 4A).

• The directional relay coils (F and R).

5-57
• FIRST SPEED, When the accelerator pedal is SUMMARY
depressed to the first speed contact MS-1 closes, You should now know about the major deck
the direction handle is placed in the forward equipment that is installed for winching operations,
position, the F contactor picks up, and the drive anchoring the ship, elevator operations, and
motor is energized. replenishment at sea. If you do not understand the
• SECOND SPEED. The pedal is depressed to the sequence of operation of this equipment, before
continuing on, review these sections. Extensive
second speed point to close contact MS-2, a
step-by-step operational methods were described, and it
positive voltage appears at TDR-1, SS-1 anode,
is essential that you know how to operate, troubleshoot,
and TDR-2 on the static timer. The positive
and repair this equipment properly. Having learned this
voltage appears at these points because of the
information thoroughly, you should be able to maintain
low-resistance path through the 1A coil. The very
the equipment in a reliable condition.
small currents needed to operate the time-delay
circuitry is about 1/100 of that needed to operate
the coil; therefore, only a small voltage is ELECTROHYDRAULIC
dropped across the coil. Now TDR-1 cannot STEERING GEAR
operate until a positive voltage also appears from
Ships have been in use almost as long as man has
either ARB or the plug. A positive voltage could
been actively exploring the earth and defending his
only come from ARB when the brake pedal is
territory. In that time, ship’s steering has evolved from
depressed. However, a small positive voltage a simple rudder of wood attached to the stem of the ship
comes through the plugging section due to the to today’s modern electrohydraulic systems.
voltage developed across the armature of the
drive motor. Now TDR-1 does operate, fires The modern or industrial era saw steering systems
SS-1, and picks up 1A coil, which provides the evolve in definite stages from steam driven to
second speed. electromechanical and finally the electrohydraulic
systems of today. Electrohydraulic steering gear was
• THIRD SPEED. The pedal is depressed to the developed to meet the power requirements of naval
third speed point to close MS-3, and a positive vessels having large displacements and high speeds with
voltage appears at TDR-2 and SS-2. Since 1A has attendant increase in rudder torques.
already picked up, a negative voltage is at the top
The steering gear is one of the most vital auxiliaries
input to TDR-2; and after a time delay, SS-2
aboard ship. It must be dependable and have sufficient
operates and 2A coil picks up, which provides the
capacity for maximum maneuverability. The ship
third speed. Now the 2A interlock leading to
steering control system for the modem ships is an
contact MS-4 closes, providing a positive voltage
integrated group of electrical, mechanical, and
to the left of contact MS-4 to ready the control of
hydraulic subsystems, equipment, and components
the fourth speed.
interconnected to provide rapid and flexible control of
• FOURTH SPEED. The pedal is depressed to the the ship’s course and maneuverability under all
fourth speed point to close contact MS-4 and to conditions of ship readiness. The ship is equipped with
open contact MS-2, which de-energizes relay two separate steering gear systems—one for each
1A. In a manner similar to the previous steps, the rudder. The steering control system coordinates
auxiliary static timer gives a time delay to the operation of the steering gear system as rudder
pickup of 4A. After 4A energizes, both normally commands constantly vary.
open 4A interlock contacts close. One shorts out The ship steering control system provides steering
the auxiliary static timer and turns it off. The control from a fixed station in the pilot house, from
other interlock lets coil 3A pick up to shunt the either bridge wing using portable steering equipment, or
field. However, relay 1A has opened; therefore, from the aft emergency steering station in the steering
afield is still present. The 4A coil picks up before gear room.
the 3A coil so that any arc that might be present
CONSTRUCTION
when the normally closed 4A contacts open will
be extinguished before 3A coil picks up. The movement of the two rudders is controlled by
Otherwise, a direct short may occur. This two mechanically independent steering gears located in
provides the fourth speed. the steering gear room (fig. 5-39). Each steering gear is

5-58
5-59
operated by a separate hydraulic system that has an Ship Control Console (SCC)
on-line power unit operating and a standby power unit
as a backup. The SCC (fig. 5-41) operates, along with other
A total steering gear system has two independent equipment, to control ship speed and heading and speed
sets of pump units and either set can operate the sliding lights, and it provides a display of ship performance and
alarms status. The SCC can detect and indicate a failure
rams to cause rudder movement, while the other power
for approximately 90% of the console electronics,
unit set is offline. Each of the steering gear assemblies
indicated on the console malfunction, power supply
operates through the function of the following systems malfunction, EOT/display alarm, or autopilot alarm
and components (fig. 5-40): indicators.

Figure 5-40.—Steering gear room (plan view).

5-60
 Figure 5-41.—Ship control console (front view).

Operational capability of the SCC permits useful if lateral visibility is of paramount importance
connection to a portable steering control unit (PSCU) during steering operations.
for alternate position steering at either bridge wing. It
can also be used with the aft steering control unit
(ASCU) for emergency steering operations from the Aft Steering Control Unit (ASCU)
steering gear room.
The ASCU, along with the steering control
switchboard and other equipment in the after steering
Portable Steering Control Unit (PSCU)
gear room, permits local control of the steering gear for
emergency steering or manual hydraulic positioning of
The PSCU provides the option of steering from the rudders if there is a loss of steering control from the
either the port or starboard bridge wing. This can be pilot house.

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Steering Control System hydraulic-operated switch, the active steering controller
of the unit acts as an LVR type, while the backup unit is
The steering control system provides rudder set to operate as an LVP type. This results in the
command inputs to the mechanical differentials which automatic restarting of the active unit after recovering
provide a mechanical rudder position command input to from a loss of power. Should the active unit fail to
each hydraulic system. restart, the steering watch stander can manually start the
backup unit.
Rudder Angle Display System
OPERATION
The rudder angle display system provides rudder
position information to those personnel concerned with The basic force used to operate the rudders is the
the ship conning tasks. pressure of the hydraulic fluid from the steering pumps.
The array of valves, piping, sensors, and controls is used
Rudder Angle Order System to send this fluid under pressure to the appropriate point
to achieve the desired change in rudder position. What
The rudder angle order system provides a nonverbal follows is the means by which this is accomplished.
means of communicating rudder commands from the
pilot house SCC to the steering gear room ASCU and Description of Operation
trick wheels.
Movement of twin rudders is provided through
Helm Wheel Angle Indicator movement of port and starboard single-ram,
mechanical] y independent, slide-type steering gears
The helm wheel angle indicator provides a located in the steering gear room. Each hydraulic
mechanical indication of the rudder command position system is controlled by a mechanical differential which
of the helm wheel or knob. provides a summing function to operate the hydraulic
pump stroking mechanism.
Ram and Follow-up Assembly
Each power unit hydraulic pump and electric pump
The ram and follow-up assembly is a mechanical is mechanically mated by a keyed coupling joining the
arrangement of components connected to the rudder respective shafts. The command module, differential
stock crosshead. The assembly reacts to hydraulic control assembly, and remote control servo units
pressure developed by the power units, causing radial (RCSUs) are clustered on a support bracket which is
movement of the rudders. mounted to the ship’s foundation and positioned at the
forward end and above the power unit electric motors.
Hydraulic Power Unit Control System A rudder angle order signal from the SCC drives a gear
train and cam assembly in the RSCU to position the
The hydraulic power unit control system remotely mechanical differential output shaft. The output shaft is
and locally controls and monitors the operation of the linked to a pump control module which positions the
four hydraulic power units. Each power unit consists of control valve which “strokes” the pump.
an electric motor directly coupled to a variable delivery As you read this section, refer to the block diagram
hydraulic pump. Each power units electric motor is
shown in figure 5-42. Once a rudder command is
individually controlled by an associated 440-volt ac,
initiated from the steering control console, a signal is
three-phase, bulkhead-mounted motor controller.
generated by the synchro transmitters. This signal is
transmitted to the RCSU. The RCSU, which has its own
Magnetic Controllers
internal control loop, drives its servo motor to the proper
position to set the cam of the steering gear mechanical
Four motor controllers, one for each steering pump
differential so that the steering gear is ordered to move
motor, are mounted on the forward bulkhead of the
the rudder in the desired position. As the cam of the
steering gear room. Control of the steering motors may
mechanical differential is moved, it puts the variable
be switched at its controller from OFF to LOCAL or
delivery pump “on stroke.” The on stroke pump
REMOTE.
provides hydraulic pressure through the automatic
Each controller may be setup to act as an LVR- or transfer valve to the appropriate side of the ram cylinder,
LVP-type controller. Through the operation of a which moves the ram in the desired direction.

5-62
 Figure 5-42.—Steering gear functional block diagram.

Movement of the ram moves the rudders and drives a Modes of Steering
feedback mechanism to the differential control to cancel
out the rudder angle order (RAO) input signal when the There are four means of controlling the operation of
rudder reaches the ordered angle, taking the pump off the steering gear. Three modes (autopilot, hand electric,
stroke. and emergency) control the movement of the rams by
Power for each steering gear is provided by one of using electric power to position valves to allow
two hydraulic pumps. The steering control system hydraulic fluid under pressure from the power units to
position the rudders. The fourth mode (manual) is
provides rudder command inputs to mechanical
totally manually driven.
differentials. Differentials then provide a mechanical
rudder position command input to each hydraulic AUTOPILOT MODE.— Steering (rudder
system. deflection) commands are generated by the autopilot
(part of the SCC) during automatic steering modes.
The rudders have a maximum working angle of 35”
These electrical commands are proportional to the
right and 35° left from the midships at rest position.
difference between the actual ship heading, as
These angles are set by an adjustment in the electronic
determined by the ships gyrocompass, and the desired
limit circuit. If there are uncontrolled surges within the
or selected ship’s heading.
hydraulic system severe enough to cause ram
overtravel, there are copper crush stops to mechanically Before the automatic steering mode is selected, the
engage the tie rod at 37° of rudder angle and steel stops ship must be steered manually (hand electric) to the
that are engaged at 38° of rudder angle. desired course to prevent uncontrolled turning rates,

5-63
which may be immediately commanded by the MAINTENANCE
autopilot. The desired heading command is set
manually into the autopilot where it is compared with The most common cause of failure of any hydraulic
the actual ship heading to produce the automatic rudder system is dirt. Because hydraulic system clearances
commands. are so precise, any amount of dirt or sludge introduced
into the system will eventually lead to problems in
HAND ELECTRIC MODE.— Steering of the Ship
operation. A differential pressure indicator is
is controlled manually by the use of the helm wheel or
mounted across a hydraulic filter in the servo system
the controls on the ASCU or the PSCU.
in the auxiliary pump discharge. Replace the filter
EMERGENCY MODE.— In the emergency element if the pressure drop across the filter exceeds
steering mode, steering control is accomplished in the 12 psig. If fluid flow is impeded, a red indicator rod
steering gear room in response to rudder commands rises from the differential pressure unit to visually
communicated by RAO indicators or orally over the warn personnel of the degree of filter blockage. If
ship interior communications system. The ASCU the red indicator rises, the filter element should be
operates in the hand electric mode and transmits rudder replaced. The filter element should be replaced every
commands through the steering control switchboard to 3 months, regardless of the pressure drop across the
the rudder command servo units. filter.

If the ASCU becomes inoperable, the trick wheels SUMMARY

are used to send rudder commands to the command
servo units manual] y and thus position the rudders. Steering is an essential element of any ship. To keep
steering dependable under all service conditions, you
MANUAL STEERING MODE.— M a n u a l must maintain and operate the steering gear and
hydraulic operation of the steering gear rams is affected associated equipment according to posted instructions
by positioning the appropriate hydraulic valves and and manuals.
hand cranking the emergency steering fill and drain
hand pumps as described below.
ELECTRIC GALLEY
• Manual positioning of the rudder is made EQUIPMENT
possible by hand operation of the emergency Electric galley equipment comprises the heavy-duty
steering/fall and drain pumps. An emergency rooking and baking equipment installed aboard naval
hydraulic system consists of hand pumps, a vessels. This equipment consists essential y of ranges,
hydraulic oil storage tank, and valves and piping griddles, deep fat fryers, roasting ovens, and baking
interconnected to the hydraulic steering system. ovens. Electric galley equipment is supplemented by
When properly lined up, hydraulic fluid is electric pantry equipment, which includes coffee urns,
applied to the ram cylinders to drive the rudders coffee makers, griddles, hotplates, and toasters. The
to the desired position. number and capacity of the units comprising a galley
• Hand pumps are operated by the normally installation depends on the size and type of ship. Galley
equipment is normally designed for operating on
stowed 15-inch handles. Either low or high
115-volt or 230-volt ac/dc or for operation on 115-volt
volume fluid flow may be selected by
or 230-volt ac/dc or 440-volt, three-phase, 60-hertz, ac
appropriately positioning a gear selector lever
power.
located on the hand pumps. Pressure relief
valves control system pressure at 650 psi.
RANGES
• The hydraulic oil storage tank provides a
93-gallon capacity for operation of the Electric galley ranges are provided in type A (36
emergency (manual) steering hydraulic system. inch), type B (20 inch), and type C (30 inch). The ranges
Normal operating level (system lines full) is consist of a range-top section and an oven section
maintained at 31 gallons. High-level caution is assembled as a single unit and a separate switchbox
monitored at 82 gallons. In addition to the designed for overhead or bulkhead mounting. Figure
emergency steering function, stored hydraulic 5-43 shows a type-A range. This range is provided with
fluid may be used to add makeup oil to the three 6-kilowatt surface units and an oven section with
steering gear hydraulic ram cylinders. two 3-kilowatt enclosed heating units.

5-64
 Figure 5-43.—Type-A range.

TYPE-60 OVEN

A type-60 oven is shown in figure 5-44. Type-60

and type-125 ovens are sectional ovens. They have
either two or three sections mounted one above the
other. Each section constitutes a separate oven that is
thermally insulated and operated independently of the
other section(s). The ovens have a separately mounted
Figure 5-44.—Type-60 oven.
switchbox that contains the fuses, the contractors, and the
three-heat switches for each section.

The heating elements are located at the top and

bottom of the oven. Each heating element is controlled
by individual three-heat switches located in a switchbox
enclosure mounted on the right-hand side of the oven.

M-SERIES CONVECTION OVEN

The M-series convection oven (fig. 5-45) is the most

common type of oven being installed aboard naval
vessels. This oven can be used individually, or more
than one oven can be stacked one on top of the other.
The construction of the ovens is rugged and has many
useful features. These features include a positive door
latch, ventical split doors, a main power light, a main
power switch, a blower motor, a thermostat, oven
chamber lights, an oven ready light, an interior light
Figure 5-45.—M-series convection oven.
switch, and a door interlock switch.

5-65
 Figure 5-46.—Wiring diagram of M-series oven.

The principle of operation of the convection oven is warping. Figure 5-47 shows a self-heating griddle. The
different from that of a standard oven. In the convection electric griddle operates on 208-, 230-, and 460-volt ac,
oven the air is forced around the chamber by the 60-hertz, single- or three-phase power. It is
motor/fan located at the rear of the oven. The thermostatically controlled and has a heating range of
convection oven heating elements are also at the rear of 200°F to 450°F±10°F. The thermostat is used to control
the oven and are controlled by a thermostat switch with
a range of 175°F to 450°F. When the doors are opened,
the fan motor and heating elements will be de-energized
because the door interlock switch opens.

The step-down transformer is 240/480 volts ac and

is used for the control circuit only. Figure 5-46 shows
a simplified wiring diagram of the M-series oven.

ELECTRIC GRIDDLE
Electric griddles are designed to be installed into
metal fixtures or fabricated tops. The tops must be rigid
enough to support the equipment weight without Figure 5-47.—Self-heating griddle.

5-66
 Figure 5-48.—Electric griddle wiring diagram.

the griddle heating unit. When one heating unit is

energized the power on light and the heating unit signal
light illuminates.
The controls are usually located in the base of the
griddle below the heated surface. Figure 5-48 shows a
wiring diagram of the electric griddle.

ELECTRIC DEEP FAT FRYER

There are various models and styles of electric deep

fat fryers. A representative model, Mk 721, is shown in
figure 5-49. Deep fat fryers can be connected to
208-volt ac, 230-volt ac/dc, or 460-volt ac power,
depending on the model and voltage requirements. Figure 5-49.—A deep fat fryer.

5-67
They can be connected in either single-phase or MAINTENANCE
three-phase configuration.
NOTE: Before starting any service work on
The deep fat fryer must not be fused, but electric galley equipment, ensure the equipment power
connected to an external circuit breaker equipped supply is secured and properly tagged out.
with a shunt trip element. The shunt trip element is
Refer to the manufacturers’ technical manuals for
connected to the (backup) upper limit thermostat. The instructions concerning the servicing of the electric
backup thermostat functions when the normal galley equipment installed aboard your ship. These
thermostat does not operate properly. When the manuals also include the methods you should use to
temperature rises to 460°F, the backup thermostat will remove and replace various heating units, thermostats,
switches, contractors, and other components of electric
operate and trip the external circuit breaker to
cooking equipment.
disconnect the deep fat fryer from the power source.
Galley equipment is normally trouble-free. The
The heating unit is an enclosed type of element and most frequent trouble with electric ranges, ovens, and
is immersed directly into the fat to ensure maximum deep fat fryers is burnt contacts. As the operating
temperature is met on the thermostat, the contactor will
efficiency. The heating unit is hinged to the back of the
open under a heavy load, causing its contact(s) to arc
fryer for ease of cleaning or for changing the liquid fat. and burn. Another common problem is corroded
connections due to prolonged exposure to heat and
The pilot light is energized at all times to indicate
grease. You should make a concentrated effort to follow
that power is available to the deep fat fryer. The power the prescribed planned maintenance, and when
on light is only energized when the heating unit is necessary, perform corrective maintenance.
energized and the unit is heating the liquid fat.
SUMMARY
The controls are located inside the deep fat fryer
enclosure. Figure 5-50 is a simplified wiring diagram The information in the preceding paragraphs is very
of the Mk 721 deep fat fryer. basic. There is no standard for the type of galley

Figure 5-50.—Wiring diagram of the Mk 721 deep fat fryer.

5-68
equipment used aboard ship, and there are hundreds of washing loads up to 60 pounds of dry weight. The
different brands and models of equipment in use. You washer-extractor has nine interrelated systems. The
can determine the basic operation of any electrical washer components are grouped into systems by the
galley equipment by using manufacturer’s manuals, major functions performed. These systems are power
bulletins, and wiring diagrams usually found on the distribution, function control, air distribution, water
equipment itself. distribution, temperature control, drive train, balance,
supply injection, and drain.
LAUNDRY EQUIPMENT
Power Distribution System
Laundry equipment aboard ship includes washers,
extractors, dryers, dry-cleaning machines, and presses. The power distribution system is 440-volt ac,
This equipment may be used as separate components or three-phase, 60-hertz. It is routed to the washer through
in combination (such as a washer-extractor). The a circuit breaker on the laundry power panel. The
washer-extractor will be the only laundry equipment 440-volt ac provides power to the four motors in the
discussed in this chapter. washer/drive train. It is reduced through a step-down
transformer to 120-volt ac, single-phase, 60-hertz power
WASHER-EXTRACTOR for use in the washer control circuitry. The 120-volt ac
power is reduced through another step-down
The washer-extractor is a front-loading, transformer to 24-volt ac, single-phase, 60-hertz power
self-balancing, general-purpose piece of equipment. for use in the washer command circuitry.
Figure 5-51 shows a front and rear view of a
washer-extractor. It is rigidly mounted to the deck in the CONTROL CIRCUITRY.— The control circuity
ship’s laundry. The washer-extractor uses ship’s energizes the washer and controls operation through the
electrical power, low-pressure air, saturated steam, and action of switches, relays, motor solenoids, and
fresh water. The washer can perform all cycles of the electrically operated solenoid valves. When the control
wash operation in formula (automatic) or manual circuit receives the proper command signal, the
(operator-controlled) mode. The washer is capable of following washer functions can occur:

Figure 5-51.—A typical washer-extractor installation.

5-69
 • The air brake can be set or released. Function Control

• The air clutch can be engaged or disengaged

The automatic control timer (fig. 5-52) is the
• The proper drive motor can be energized or function control system for the washer-extractor.
de-energized Command and control signals are routed by finger
contacts and/or switches in the control timer to sequence
• The chart motor can advance the formula chart
functions and cycles within an operation during formula
(formula mode). or manual mode.
• The washer balance system can operate.
FORMULA MODE.— A programmed formula
• The washer door can be opened. chart (fig. 5-53) is mounted on the rotating drum/copper
screen inside the control timer. During the formula
COMMAND CIRCUITRY.— The 24-volt ac mode, the drum rotates and finger contacts press against
command circuit generates command signals through the chart. As a finger contact passes over a slot in the
the action of finger contacts and/or toggle switches. The chart, it touches the copper screen. This completes an
command signals are routed throughout the washer to electrical circuit and generates a command signal. Each
open and/or close relays and solenoid valves. The relays finger contact controls a different command signal. The
and solenoid valves sequence and control the duration chart can control the wash operation by programming
of functions and/or cycles during a wash operation. the time and duration of finger contact on the screen.

Figure 5-52.—A typical automatic control timer.

5-70
Figure 5-53.—Programmed formula chart.

5-71
 MANUAL MODE.— In the manual mode the Temperature Control
command signals are generated by toggle switches. An
operator positions these switches for specific functions Three motometers comprise the temperature control
and/or cycles. The function and/or cycle is ended by system. Motometers are combination thermometers
returning the appropriate toggle switch to OFF. and thermostats. Each motometer has three indicator
pointers-one for indicating existing temperature and
Air Distribution two for setting desired temperatures. Water and/or
steam are automatically injected to bring the
The air distribution system uses ship’s service temperature to the preset value.
compressed air to operate the brake and clutch
assemblies. Electrically controlled solenoid valves Drive Train
connected to the air manifold distribute the compressed
air as signaled by the command or control circuits. The Figure 5-54 shows the washer drive train. Each
air operates valves controlling the washer drain, the drive motor provides a different rotational speed to the
steam supply, and the bottom fill valve. The air also washer cylinder and is used during separate cycles.
actuates the air brake and the air clutch. During wash or drain cycles, the drive is from the
appropriate motor through a V-belt coupling to the gear
Freshwater Distribution reducer and clutch. The inflated (engaged) clutch
causes the drive shaft and the washer cylinder to rotate
The freshwater distribution system is used for at the wash or drain speed. During low-speed or
washing and rinsing. Some fresh water is also used by high-speed extract cycles, the drive is from the
the temperature control system, the balance system, and appropriate motor through a V-belt coupling directly to
the supply injection system. the clutch/brake drum pulley. The pulley, connected to

Figure 5-54.—Wash drive train.

5-72
the drive shaft, rotates the washer cylinder at low or high SAFETY
speed. The clutch is not engaged during extract cycles.
Never exceed the dry weight cylinder capacity (60
pounds); however, loading the cylinder to capacity is
Balance
recommended Lighter loads may fail to distribute
clothes properly. This will cause the machine to vibrate
The balance system automatically corrects excessively. Before performing maintenance on the
imbalances that occur during extract cycles in either machine, ensure it is de-energized and tagged out
formula or manual mode operation. An imbalance according to your ship’s tag-out program.
causes washer vibrations that are transmitted through a
rigidly mounted arm to a hydraulic sensor unit. The unit For additional information on the operation, the
converts the vibrations to electric impulse signals that troubleshooting, and the repair of the washer-extractor
operate electric balance solenoid valves. When a installed aboard your ship, refer to the manufacturer’s
solenoid valve opens, hot water from the water technical manual.
distribution system is injected into a cylinder rib
opposite the point of imbalance. OTHER LAUNDRY EQUIPMENT

For other laundry equipment, such as dry-cleaning

Supply Injection machines, dryers, and presses, refer to the appropriate
manufacturer’s instruction manual for operational
procedures, troubleshooting, and repairs.
You can use the manual supply chute in either
operational mode. Supplies, such as soap, bleach,
conditioner, and so forth, are poured directly into the SUMMARY
chute. The automatic injection system is used only
In this chapter you have been introduced to
during formula mode operations. Initial soap is placed
information on various components of electrical
in the manual supply chute, and additional laundry
equipment. These components include small craft
supplies are loaded into the appropriate compartment at
electrical systems, the ship’s air compressors, the
the start of wash operations. When the programmed
refrigeration and air-conditioning plants, the
formula chart calls for a supply injection, a command
electrostatic vent fog precipitators, the electrohydraulic
signal is generated by a finger contact in the control
steering gear, and the ship’s deck equipment. Some of
timer. The signal opens a solenoid valve, and then water
from the water distribution system enters the the smaller auxiliary equipment components that have
been discussed include battery chargers and storage
appropriate supply compartment and flushes the
batteries and components. We also described various
contents into the washer.
deck equipment, including winches, anchor windlasses,
elevators, and UNREP systems. Some galley and
Drain laundry equipment were also described and explained.
The installations aboard your ship may differ, but
The washer main drain is mounted directly onto the the information given is basic in nature and should be
bottom of the washer shell. The main drain valve is of some use in determining the proper course of action
controlled by a solenoid valve in the air distribution when operating and maintaining the vast amount of
system manifold. auxiliary electrical equipment aboard ship.

5-73
 CHAPTER 6

MOTOR CONTROLLERS

Controllers are commonly used for starting motors for acceleration of the motor to avoid high
aboard ship. They can be designed to limit the amount starting current.
of current applied when starting motors by slowly
incrementing the starting process, allow the user to MANUAL
select the speed at which the motor will operate, allow
the operator to reverse the direction of rotation of a A manual (nonautomatic) controller is operated by
motor, remove the motor from service if conditions exist hand directly through a mechanical system. The
which may damage the motor or other connected operator closes and opens the contacts that normally
equipment, allow the user to operate the motor under energize and de-energize the connected load.
adverse conditions in an emergency, and so forth. In all
cases, the basic function of motor controllers is to MAGNETIC
govern the operation of and protect the motors they
serve. In a magnetic controller, the contacts are closed or
opened by electromechanical devices operated by local
or remote master switches. Norman y, all the functions
LEARNING OBJECTIVES of a semiautomatic magnetic controller are governed by
Upon completing this chapter, you should be able one or more manual master switches. Automatic
to do the following: controller functions are governed by one or more
automatic master switches after the motor has been
1. Identify the different types of electric initially energized by a manual master switch. All
controllers. magnetic controllers can be operated in either mode,
2. Recognize the principle of operation of various depending on the mode of operation selected.
types of motor controllers.
ACROSS-THE-LINE CONTROLLER
3. Identify the procedures for troubleshooting
motor controllers. An across-the-line controller (fig. 6-1) throws the
4. Identify the procedures to use when performing connected load directly across the main supply line. The
corrective maintenance on motor controllers. across-the-line controller may be either manual or
magnetic, depending on the rated horsepower of the
In this chapter, you will learn the characteristics, the
motor. Norman y, across-the-line dc controllers are used
uses, and the operating principles of the various kinds
to start small (fractional horsepower) motors. However,
of shipboard motor controllers, including their relays
they may be used to start average-sized, squirrel-cage
and switches. The techniques for maintaining and
induction motors without any damage because these
troubleshooting motor controllers are also discussed.

TYPES OF MOTOR
CONTROLLERS
Motor controllers are classified as manual or
automatic (magnetic). They are further classified b y the
methods by which they are started-across-the-line and
reduced voltage.

• Across-the-line motors are started with full-line

voltage being immediate] y applied to the motor.

• Reduced voltage motors are started by applying

line voltage to the motor in increments to allow Figure 6-1.—Schematic of a simple across-the-line controller.

6-1
motors can withstand the high starting currents caused
by starting with full-line voltage applied. Most
squirrel-cage motors drive pumps, compressors, fans,
lathes, and other auxiliaries. They can be started “across
the line” without producing excessive line-voltage drop
or mechanical shock to a motor or auxiliary.

AC PRIMARY RESISTOR CONTROLLER

In an ac primary resistor controller, resistors are

inserted in the primary circuit of an ac motor for both
starting and speed control. Some of these controllers
only limit the starting currents of large motors; others
control the speed of small motors, as well as limiting the
starting current.
Figure 6-2 illustrates the use of resistors to limit the
amount of starting current.

AC SECONDARY RESISTOR
CONTROLLER

In an ac secondary resistor controller (fig. 6-3),

resistors are inserted in the secondary circuit of a
wound-rotor ac motor for starting or speed control. Figure 6-3.—Schematic of an ac secondary resistor controller.
Although sometimes they are used to limit starting
currents, secondary resistor controllers usually function
to regulate the speeds of large ac motors. (fig. 6-4) starts the motor at a reduced voltage through
an autotransformer and then connects the motor to line
AUTOTRANSFORMER CONTROLLER voltage after the motor accelerates. There are two types
of compensators—open transition and closed transition.
The autotransformer controller (or compensator) is
an ac motor controller. The autotransformer controller

Figure 6-2.—Schematic of an ac primary resistor controller. Figure 6-4.—Schematic of an autotransformer controller.

6-2
Open-Transition Autotransformer
The open-transition compensator cuts off power to
the motor during the time (transition period) that the
motor connection is shifted from the autotransformer to
the supply line. In this short transition period, it is
possible for the motor to coast and slip out of phase with
the power supply. After the motor is connected directly
to the supply line, the resulting transition current may
be high enough to cause circuit breakers to open.

Closed-Transition Autotransformer
The closed-transition compensator keeps the motor
connected to the supply line during the entire transition
period. In this method, the motor cannot slip out of
phase and no high transition current can develop. Figure 6-6.—Schematic of a reversing ac controller.

REACTOR CONTROLLER by interchanging any two of the three lines providing

A reactor controller (fig. 6-5) inserts a reactor in the power to the motor. Look at figure 6-6. Standard
primary circuit of an ac motor during starts and later practice when reversing three-phase ac motors is to
short-circuits the reactor to apply line voltage to the interchange L1 and L3.
motor. The reactor controller is not widely used for DC motors are reversed by reversing the
starting large ac motors. It is smaller than the connections to the armature. DC controllers accomplish
closed-transition compensator and does not have the this through the use of drum switches.
high transition currents that develop in the
open-transition compensator. VARIABLE-SPEED CONTROLLER

REVERSING CONTROLLER A motor static variable-speed controller consists of

solid-state and other devices that regulate motor speeds
Reversing controllers act to change line connections in indefinite increments through a predetermined range.
to the motors under control causing the direction of Speed is controlled by either manual adjustment or
rotation to reverse. Three-phase ac motors are reversed actuation of a sensing device that converts a system
parameter, such as temperature, into an electric signal.
This signal sets the motor speed automatically.

DC RESISTOR CONTROLLER
In a dc resistor motor controller (fig. 6-7), a resistor
in series with the armature circuit of the dc motor limits
the amount of current during starts, thereby preventing

Figure 6-7.—Schematic of a dc resistor controller with one

Figure 6-5.—Schematic of a reactor controller. stage of acceleration.

6-3
motor damage and overloading the power system. In ENCLOSURES
some resistor controllers, the same resistor also helps
regulate the speed of the motor after it is started. Other The components of the controller are housed within
dc controllers use a rheostat in the motor shunt field an enclosure suitable to its location, atmospheric
circuit for speed control. condition, or presence of explosive vapors or liquids.
Enclosures provide mechanical and electrical protection
LOGIC CONTROLLERS for both the operator and the motor starter. Controller
enclosures can be classified in the following ways:
Some of the controlled equipment that you will see
• Open. Open enclosures provide the least amount
uses logic systems for circuit control. For additional
information in this area, the Navy Electricity and of protection from dust and moisture. Provides
Electronics Training Series (NEETS), Module 13, maximum ventilation to internals.
NAVEDTRA B72-13-00-86, Introduction to Number • Dripproof. Dripproff enclosures are the most
Systems and Logic Circuits, is an excellent basic common type found aboard ship. They are
reference. constructed so that liquid or solid particles can’t
enter the enclosure when striking at an angle of
CONSTRUCTION 0° to 15° from the downward vertical.

In this section of the TRAMAN, you will learn how • Spraytight. Spraytight enclosures provide more
controllers are constructed. than usual protection from casual water. They are
constructed to prevent entry of water from spray
SIZE DESIGNATION at any angle not greater than 100° from the
vertical.
Controllers are sized numerically according to the
maximum horsepower rating of their connected loads. • Watertight. Watertight enclosures are
Generally, the numbers zero to five (0-5) are used; constructed so that water sprayed from any angle
however, in special circumstances, controllers as large will be unable to enter the enclosure.
as 6, 7, or 8 may be used. AC controllers that are • Submersible. Submersible enclosures are
connected to two-speed motors have two numbers
constructed so that water can’t enter when the
separated by a slash. The larger number indicates the
unit is submerged underwater. Provides least
rating of the controller at motor fast speed, while the
amount of ventilation to internal components.
smaller number indicates the rating at motor slow speed.
• Explosionproof. Explosionproof enclosures are
The controller sizes given in table 6-1 apply to both
constructed so that no gas vapor can penetrate
ac and dc controllers.
except through vents or piping provided for the
Table 6-1.—AC and DC Controller Sizes
purpose.

MASTER SWITCHES

A master switch is a device, such as a pressure or a

thermostatic switch, that governs the electrical
operation of a motor controller. The master switch (fig.
6-8) can be manually or automatically actuated. Drum,
selector, and push-button switches are examples of a
manual master switch. The automatic switch is actuated
by a physical force, not an operator. Examples of
automatic master switches include float, limit, or
pressure switches.
Depending on where it is mounted, a master switch
is said to be either local or remote. A local switch is
mounted in the controller enclosure, while a remote
switch is mounted near the watchstation or work area
where the motor is to be controlled from.

6-4
 Figure 6-8.—Rotary snap switch.

Master switches may start a series of operations

when their contacts are either closed or opened. In a
momentary contact master switch, the contact is closed
(or opened) momentarily; it then returns to its original
condition. In the maintaining contact master switch, the
contact does not return to its original condition after
closing (or opening) until it is again actuated. The
Figure 6-9.—Detailed view of arcing contacts.
position of a normally open or normally closed contact
in a master switch is open or closed, respectively, when
the switch is de-energized. The de-energized condition The blowout shield has been removed in this detailed
of a manual controller is considered to be in the OFF view. As you read this section refer to figure 6-9.
position The arcing contacts (1) are made of rolled copper
with a heavy protective coating of cadmium. These
CONTRACTORS contacts are self-cleaning because of the sliding or
wiping action following the initial contact. The wiping
Contractors are the heart of any controller. They action keeps the surface bright and clean, and thus
operate to open and close the contacts that energize and maintains a low contact resistance.
de-energize connected loads.
The contactor is operated by connecting the coil (2)
directly across a source of dc voltage. When the coil is
DC Contractors energized, the movable armature (3) is pulled toward the
stationary magnet core (4). This action causes the
A dc contactor is composed of an operating magnet contacts that carry current (5, 6, 7, and 1) to close with
energized by either switches or relays, fixed contacts, a sliding action
and moving contacts. It maybe used to handle the load
The main contacts (5 and 6), called brush contacts,
of an entire bus or a single circuit or device. Larger
are made of thin leaves of copper that are backed by
contacts must be used when heavy currents are to be
several layers of phosphor bronze spring metal. A silver
interrupted. These contacts must snap open or closed to
brush arcing tip (7) is attached to the copper leaves and
reduce contact arcing and burning. In addition to these,
makes contact slightly before the leaf contact closes.
other arc-quenching means are used.
The stationary contact (5) consists of a brass plate,
ARCING CONTACTS.— The shunt contactor which has a silver-plated surface. Since the plating
shown in figure 6-9 uses a second set of contacts (1) to lowers the surface resistance, the contact surfaces
reduce the amount of arcing across the main contacts (5 should never be filed or oiled. If excessive current
and 6) when closing. The numbers that are in causes high spots on the contact, the high places maybe
parentheses are indicated on the figure. Shunt-type smoothed down by careful use of a fine ignition-type
contractors will handle up to 600 amperes at 230 volts. file.

6-5
 You can check the operation and contact spacing by chosen to match the current so that the correct amount
manually closing the contactor (be sure the power is of flux may be obtained. The blowout flux across the
off). The lowest leaf of brush contact 6 should just arc gap is concentrated by the magnetic path provided
barely touch contact 5. If the lower leaf hits the plate by the steel core in the blowout coil and by the steel pole
too soon, bend the entire brush assembly upward pieces extending from the core to either side of the gap.
slightly. The contact dimensions should be measured
with the contactor in the OPEN position.
AC Contractors
Refer to the manufacturer’s instruction book when
making these adjustments.
AC contractors (fig. 6-11) and control relays differ
BLOWOUT COILS.— When a circuit carrying a from DC contractors and control relays in three general
high current is interrupted, the collapse of the flux areas:
linking the circuit will induce a voltage, which will
cause an arc. If the spacing between the open contacts 1. For heavy currents, ac contractors generally use
is small, the arc will continue once it is started. If the an air gap alone to quench the arc created by
arc continues long enough, it will either melt the opening energized contacts while dc contractors
contacts or weld them together. Magnetic blowout coils use blowout coils.
overcome this condition by providing a magnetic field 2. AC contractors are noisier than dc contractors.
that pushes the arc away from the contact area. Shading bands are sometimes used on ac
The magnetic blowout operation is shown in figure contactor cores to reduce noise and produce
6-10. It is important that the fluxes remain in the proper smoother operation.
relationship. Otherwise, if the direction of the current 3. The coil of an ac contactor contains fewer turns
is changed, the direction of the blowout flux will be of wire than a dc contactor for the same voltage;
reversed, and the arc will actually be pulled into the therefore, it depends on inductive reactance to
space between the contacts. produce counterelectromotive force (cemf) to
When the direction of electron flow and flux is as limit current flow in the coil. If an ac contactor
shown in figure 6-10, the blowout force is upward. The fails to close completely, an air gap will exist in
blowout effect varies with the magnitude of the current the magnetic circuit. This air gap reduces the
and with the blowout flux. The blowout coil should be amount of cemf produced which reduces the
ability of the coil to protect itself and may lead
to burnout of the coil.
The operating parts of the contactor must be kept
clean and free to operate to prevent burnout of the coils.
A regular maintenance routine of cleaning and circuit
testing according to prescribed PMS will keep
contractors free of trouble for years of operation.

CONTROLLER OPERATION

The operation of the various types of controllers is

discussed in this section of the TRAMAN.

MAGNETIC ACROSS-THE-LINE
CONTROLLERS

Across-the-line controllers are the most common

motor controllers you will encounter aboard ship. Of
Figure 6-10.—Action of a magnetic blowout coil. the three types (LVP, LVR, and LVRE), LVPs are most
often used aboard ship to control/protect motors.

6-6
Figure 6-11.—AC contactor.

6-7
 Low-Voltage Release (LVR)

The LVR controller (fig. 6-13) operates in basically

the same way as the LVP controller, except that its start
switch is a maintaining-type switch, such as a snap
switch. This makes the use of a maintaining circuit,
through an auxiliary contact in parallel with the start
switch, unnecessary.

If power is lost to a motor supplied by an LVR

contactor while it is operating, the motor will stop just
as if it had been turned off. Once power is restored, the
Figure 6-12.—Schematic of a simple LVP controller. motor will restart since the start circuit was maintained
through the maintaining-type start switch. For this
reason, motors that drive loads requiring some setup by
Low-Voltage Protection (LVP) the operator before being energized are normally
controlled by LVP controllers.

An elementary or schematic diagram of an LVP Low-Voltage Release Effect

magnetic controller is shown in figure 6-12. Table 6-2 (LVRE)
describes the sequence of operation in starting the
motor: The LVRE controller is actually a simple switch. It
Table 6-2.—Operation of a Simple LVP Controller operates in the same way as the LVR controller, except
that it doesn’t have a coil in its circuit to operate contacts.
The main contacts are operated by the operator
manually opening and closing the start switch. A
household light switch is an example of an LVRE
controller.

SPEED SELECTION CONTROLLERS

Both ac and dc motors maybe designed to operate

at more than one speed. In each case, controllers are
used to select the desired operating speed and protect
the motor.

The most common type of motor in the fleet is the

ac, squirrel-cage induction motor. The speed of this

The motor will continue to run until the contactor

coil is de-energized by the stop push button, failure of Figure 6-13.—Schematic of simple LVR controller.
the line voltage, or tripping of the overload relay, OL.

6-8
motors depends on the speed of the rotating magnetic
field (also known as the synchronous speed). The
synchronous speed depends on the following factors:
1. The number of magnetic poles in the motor, and
2. The frequency of the power supplied to it
This can be expressed mathematically as:

where: f= frequency of the voltage supplied to the

motor
N = synchronous speed Figure 6-14.—Two-speed, ac controller.

P= number of magnetic poles in the stator Table 6-3.—High-Speed Operation of a Two-speed AC Motor

Since it isn’t desirable to change the frequency

throughout the ship to change motor speed, the speed of
ac motors is changed by altering the number of magnetic
poles. The number of magnetic poles in ac motors is
varied by changing connections to the motor through the
controller.

The speed of dc motors can be controlled by varying

the voltage to the motor. An arrangement of resistors is
used along with the controller to operate the motor at the
desired speed.

AC Speed Selection The motor will run at high speed until coil HM is
de-energized either by opening the stop switch, a power
failure, or an overload.
An ac induction motor designed for two-speed
operation may have either a single set of windings or The Low-Speed operation of the controller is shown
two separate sets of windings, one for each speed. in table 6-4.
Figure 6-14 is a schematic diagram of the ac controller Table 6-4.—Low-Speed Operation of a Two-Speed AC Motor
for a two-speed, two-winding induction motor. The
low-speed winding is connected to terminals T 1, T2, and
T3. The high-speed winding is connected to terminals
T11, and T13. Overload protection is provided by
the LOL coils and contacts for the low-speed winding
and the HOL contacts and coils for the high-speed
winding. The LOL and HOL contacts are connected in
series in the maintaining circuit, and both contacts must
be closed before the motor will operate at either speed.

The control push buttons are the

momentary-contact type. High-speed operation of the
controller in figure 6-14 is shown in table 6-3.

6-9
 Figure 6-15.—A two-speed de controller with shunt field rheostat.

The motor will run at low speed until coil LM is Table 6-5.—Operation of slow-speed circuit
de-energized. The LM and HM contractors are
mechanically interlocked to prevent both from closing
at the same time.

DC Speed Selection

The speed of dc motors is determined by the amount

of current flowing through both the field winding and
the armature winding. If resistance is added in series
with the shunt field (fig. 6-15), the current through the
shunt field winding will be decreased. The decreased
field strength will momentarily decrease the amount of
cemf produced, and the motor will sped up. Once the
motor speeds up the amount of cemf will rise and again
limit the armature current.

In a similar manner, a decrease in resistance

increases the current flow through the field windings,
momentarily increases the production of cemf, and
slows the motor down.

The operation of the slow-speed circuit is shown in

table 6-5.

6-10
 Setting the start switch to high speed causes steps 1
to 5 above to be repeated. This is followed by the
sequence of events listed in table 6-6.
Table 6-6.—Operation of High-Speed Circuit

Figure 6-16.—Reversing ac controller.

Table 6-7.—Forward Operation of a Reversing AC Controller

REVERSING CONTROLLERS

Certain applications call for the ability to reverse the

direction of rotation of installed motors aboard ship.
Whether the motor is ac or dc, the method used to
reverse the direction of rotation is to change the
connections of the motor to the line. Motor controller
controllers make this a quick, simple process.

AC Motors

The rotation of a three-phase induction motor is

reversed by interchanging any two of the three leads to
the motor. The connections for an ac reversing
controller are shown in figure 6-16. The stop, reverse,
and forward push-button controls are all momentary
contact switches. Note the connections to the reverse
and forward switch contacts. (Their contacts close or
open momentarily, then return to their original closed or If either the stop button or the reverse button is
opened condition.) pressed, the circuit to the F contactor coil is broken, and
the coil releases and opens line contacts F1, F2, and F3,
The operation of the reversing ac motor controller and maintaining contact F4.
in the forward position is shown in table 6-7. After the
forward push button is pressed:

6-11
 The operation of the reversing motor in the reverse
position is shown in table 6-8. After the reverse push
button is pressed (solid to dotted position):

Table 6-8—Reverse Operation of a Reversing AC Controller

The F and R contractors are both mechanically and Figure 6-17.—Reversing dc controller.
electrically interlocked to prevent both being closed at
the same time.
The forward operation of the reversing dc controller
Momentary contact push buttons provide is given in table 6-9.
low-voltage protection with manual restart in the
Table 6-9.—Forward Operation of a DC Controller
circuit shown in figure 6-16. If either the F or R
operating coil is de-energized, the contactor will not
reclose and start the motor when voltage is restored
unless either the forward or reverse push button is
pressed. The circuit arrangement of the normally
closed contacts F 5 and R5 provides an electrical
interlock that prevents the energizing of both coils at the
same time.

DC Motors

In most applications, the direction in which a dc

motor turns is reversed by reversing the connections of
the armature with respect to the field. The reversal of
connections can be done in the motor controller by
adding two electrically and mechanically interlocked
contractors.

A dc motor reversing connection is shown in figure

6-17. Note that there are two start buttons—one marked
START-EMERG FORWARD and the other marked
START-EMERG REVERSE. These buttons serve as
master switches, and you can get the desired motor After the line contactor is energized, acceleration is
rotation by pressing the proper switch. accomplished in the reamer described previously.

6-12
 Operating the reverse button duplicates the steps for winding between B and C. In the part of the winding
the forward button described in table 6-9 with the that is between A and B, the load current of 7 amperes
exception of the F1 and F2 contacts. The R1 and R2 is opposed by the line current of 2.22 amperes.
contacts are closed to reverse the direction of current Therefore, the current through this section is equal to
through the armature and thus the direction of rotation. the difference between the load current and the line
current. If you subtract 2.22 amperes from 7
AUTOTRANSFORMER amperes, you will find the secondary current is 4.78
CONTROLLERS amperes.
Autotransformers are commonly used to start
A single-phase autotransformer has a tapped three-phase induction and synchronous motors and to
winding on a laminated core. Normally, only one coil furnish variable voltage for test panels. Figure 6-19
is used on a core, but it is possible to have two shows an autotransformer motor starter, which
autotransformer coils on the same core. Figure 6-18 incorporates starting and running magnetic contractors,
shows the connections for a single-phase an autotransformer, a thermal overload relay, and a
autotransformer being used to step down voltage. ‘he mercury timer to control the duration of the starting
winding between A and B is common to both the primary cycle.
and the secondary windings and carries a current that is
equal to the difference between the load current and the
ONE-STAGE ACCELERATION
supply current.
CONTROLLERS
Any voltage applied to terminals A and C will be
uniformly distributed across the winding in proportion Figure 6-20 shows a typical dc controller. The
to the number of turns. Therefore, any voltage that is connections for this motor controller with one stage of
less than the source voltage can be obtained by tapping
the proper point on the winding between terminals A and
c.

Some autotransformers are designed so that a

knob-controlled slider makes contact with wires of the
winding in order to vary the load voltage.
The directions for current flow through the line,
transformer winding, and load are shown by the arrows
in figure 6-18. Note that the line current is 2.22 amperes
and that this current also flows through the part of the

Figure 6-18.—Single-phase autotransformer. Figure 6-19.—Autotransformer controller.

6-13
 Figure 6-20.—A typical dc controller.

acceleration are shown in figure 6-21. The letters that

are in parentheses are indicated in figure 6-21. When
the start button is pressed, the path for current is from
the line terminal (L2) through the control fuse, the stop
button, the start button, and the line contactor coil (LC),
to the line terminal (L1). Current flowing through the
contactor coil causes the armature to pull in and close
the line contacts (LC1, LC2, LC3, and LC4).
When contacts LC1 and LC2 close, motor-starting
current flows through the series field (SE), the armature
(A), the series relay coil (SR), the starting resistor (R),
and the overload relay coil (OL). At the same time, the Figure 6-21.—A dc controller with one stage of acceleration.

6-14
shunt field winding (SH) is connected across the line
and establishes normal shunt field strength. Contacts
LC3 close and prepare the circuit for the accelerating
contactor coil (AC). Contacts LC4 close the holding
circuit for the line contactor coil (LC).
The motor armature current flowing through the
series relay coil causes its armature to pull in, opening
the normally closed contacts (SR). As the motor speed
picks up, the armature current drawn from the line
decreases. At approximately 110 percent of normal
running current, the series relay current is not strong
enough to hold the armature in; therefore, it drops out
and closes its contacts (SR). These contacts are in series
with the accelerating relay coil (AC), and cause it to pick
up its armature, closing contacts AC1 and AC2.

Auxiliary contacts (AC1) on the accelerating relay Figure 6-22.—AND symbol and circuit.
keep the circuit to the relay coil closed while the main
contacts (AC2) short out the starting resistor and the
series relay coil. The motor is then connected directly AND and OR logic circuits are used in logic
across the line, and the connection is maintained until controllers. Their use is discussed in this section of the
the STOP button is pressed. TRAMAN.

If the motor becomes overloaded, the excessive One common application of logic control that is
current through the overload coil (OL) (at the top right being incorporated on newer ships is the elevator
of fig. 6-21) will open the overload contacts (OL) (at the system. Since this system is large and consists of many
bottom of fig. 6-21), disconnecting the motor from the symbols, only a small portion of this system is
line discussed.

If the main contactor drops out because of an Assume that the elevator platform is on the third
excessive drop in line voltage or a power failure, the deck and that you require it on the main deck. Refer to
motor will remain disconnected from the line until an
operator restarts it with the START push button. This
prevents automatic restarting of equipment when
normal power is restored.

LOGIC CONTROLLERS

The basic concept of logic circuits is shown in

figures 6-22 and 6-23. As you read this section, refer to
these figures.

In figure 6-22, view A, an AND symbol is shown.

The AND symbol can be compared to the electrical
circuit in figure 6-22, view B. (NOTE: Both switches
A AND B must be closed to energize the lamp.)

In figure 6-23, view A, an OR symbol is shown. The

OR symbol can be compared to the electrical circuit in
figure 6-23, view B. (NOTE: Either switch A OR B
needs to be closed to energize the lamp.) Figure 6-23.—OR symbol and circuit.

6-15
figure 6-24. Three conditions (detected by electronic section describes the various means of protection
sensors usually associated with the driven component) available to motors by the controller used.
must be met before the elevator can be safely moved.
VOLTAGE PROTECTION

A drop in voltage supplied to a motor under load

could severely damage the motor windings. If allowed
to remain on the line, the current through the windings
could become excessive and cause damage to the motor.
Low voltage type controllers (LVP, LVR, and
LVRE) are designed to remove a motor from the line
upon a drop in line voltage. Once line voltage drops to
a predetermined level, the main contactor coil (or an
undervoltage coil controlling it) will dropout. This will
function to open its contacts and remove the motor from
the line.
Once line voltage has been restored, the motor may
be restarted normally.

OVERLOAD PROTECTION

Nearly all shipboard motor controllers provide

overload protection when motor current is excessive.
This protection is provided by either thermal or
magnetic overload relays, which disconnect the motor
from its power supply, thereby preventing the motor
from overheating.

Overload relays in magnetic controllers have a

normally closed contact that is opened by a mechanical
device, which is tripped by an overload current. The
opening of the overload relay contact de-energizes the
Figure 6-24.—Basic logic circuit. circuit through the operating coil of the main contactor,
causing the main contactor to open, and secures power
The advantages of these electronic switches over to the motor.
mechanical switches are low power consumption, no
moving parts, less maintenance, quicker response, and Overload relays for naval shipboard use can usually
less space requirements. A typical static logic panel be adjusted to trip at the correct current to protect the
motor. If the rated tripping current of the relay does not
found aboard ship is shown in figure 6-25.
fit the motor it is intended to protect, it can be reset after
Although there are more logic symbols than AND tripping so the motor can be operated again with
and OR, they all incorporate solid-state devices. For overload protection. Some controllers feature an
more information, see NEETS, Module 7, NAVEDTRA emergent y-run button that enables the motor to be run
B72-07-00-92, Introduction to Solid-State Devices and without overload protection during an emergency.
Power Supplies.
Thermal Overload Relays
PROTECTIVE FEATURES
The thermal overload relay has a heat-sensitive
As its name implies, the primary purpose of motor element and an overload heater that is connected in
controllers is to control the operation of the motor series with the motor load circuit. When the motor
connected. In accomplishing this function, it is current is excessive, heat from the heater causes the
imperative that the controller be able to operate as well heat-sensitive element to open the overload relay
as protect the motor being controlled. The following contact. This action breaks the circuit through the

6-16
 Figure 6-25.—A static logic panel for a cargo elevator.

operating coil of the main contactor and disconnects the unaffected by variations in the ambient (room)
motor from the power supply. Since it takes time for the temperature. Different compensation methods are used
parts to heat up, the thermal overload relay has an for different types of thermal overload relays. Refer to
inherent time delay, which allows the motor to draw the technical manual furnished with the equipment on
excessive current at start without tripping the motor. which the controller is used for information on the
You can make a coarse adjustment of the tripping particular form of compensation provided. There are
current of thermal overload relays as follows: four types of thermal overload relays—solder pot,
bimetal, single metal, and induction.
• Change the heater element. SOLDER POT THERMAL OVERLOAD
• Change the distance between the heater and the RELAY.— The heat-sensitive element of a solder-pot
heat-sensitive element to make a fine adjustment. relay consists of a cylinder inside a hollow tube. The
An increase in this distance increases the tripping cylinder and tube are normally held together by a film
current. (NOTE: Making fine adjustments of solder. In case of an overload, the heater melts the
depends on the type of overload relay.) solder (thereby breaking the bond between the cylinder
and tube) and releases the tripping device of the relay.
• Change the distance the bimetal strip has to move After the relay trips, the solder cools and solidifies. The
before the overload relay contact is opened. relay can then be reset.
Check the related technical manual for additional BIMETAL THERMAL OVERLOAD
information and adjustments. RELAY.— In the bimetal relay, the heat-sensitive
Thermal overload relays must be compensated; that element is a strip or coil of two different metals fused
is, they are constructed so the tripping current is together along one side. When heated, the strip or coil

6-17
deflects because one metal expands more than the other. In either the instantaneous or time-delay magnetic
The deflection causes the overload relay contact to open. overload relays, you can adjust the tripping currents by
changing the distance between the series coil and the
SINGLE-METAL THERMAL OVERLOAD
tripping armature. More current is needed to move the
RELAY.— The heat-sensitive element of the
armature when the distance is increased. Compensation
single-metal relay is a tube around the heater. The tube
for changes in ambient temperature is not needed for
lengthens when heated and opens the overload relay
magnetic relays because they are practically unaffected
contact.
by changes in temperature.
INDUCTION THERMAL OVERLOAD
RELAY.— The heater in the induction relay consists of Overload Relay Resets
a coil in the motor circuit and a copper tube inside the
coil. The tube acts as the short-circuited secondary of a After an overload relay has operated to stop a motor,
transformer and is heated by the current induced in it. it must be reset before the motor can be started again.
The heat-sensitive element is usually a bimetal strip or Magnetic overload relays can be reset immediately after
coil. Unlike the other three types of thermal overload tripping. Thermal overload relays must Cool a minute
relays that may be used with either ac or dc, the or longer before they can be reset. The type of overload
induction type is manufactured for ac use only. reset may be manual, automatic, or electric.
The manual, or hand, reset is usually located in the
Magnetic Overload Relays controller enclosure, which contains the overload relay.
This type of reset usually has a hand-operated rod, lever,
The magnetic overload relay has a coil connected in or button that returns the relay tripping mechanism to its
series with the motor circuit and a tripping armature or original position, resetting interlocks as well, so that the
plunger. When the normal motor current exceeds the motor can be run again with overload protection. (An
tripping current, the contacts open the overload relay. interlock is a mechanical or electrical device in which
Though limited in application, one type of magnetic the operation of one part or mechanism automatically
overload relay is the instantaneous overload relay. This brings about or prevents the operation of another.)
type operates instantly when the motor current exceeds The automatic type of reset usually has a spring- or
the tripping current. It must be set at a higher tripping gravity-operated device, resetting the overload relay
current than the motor starting current because the relay without the help of an operator. The electric reset is
would trip each time you start the motor. Instantaneous actuated by an electromagnet controlled by a push
magnetic overload relays are used in motor controllers
button. This form of overload reset is used when it is
for reduced voltage starting where the starting current desired to reset an overload relay from a remote
peaks are less than the stalled rotor current. operating point.
The second type of magnetic overload relay is
time-delay magnetic overload relay. It delays a short EMERGENCY RUN FEATURE
time when the motor current exceeds the tripping
current. This type of relay is essential y the same as the Motor controllers having emergency-run features
instantaneous relay except for the time-delay device. are used with auxiliaries that cannot be stopped safely
This is usually an oil dashpot with a piston attached to in the midst of an operating cycle. This type of feature
the tripping armature of the relay. Oil passes through a allows the operator of the equipment to keep it running
hole in the piston when the tripping armature is moved with the motor overloaded until a standby unit can take
by an overload current. The size of the hole can be over, the operating cycle is completed, or the emergency
adjusted to change the speed at which the piston moves passes
for a given pull on the tripping armature. For a given
size hole, the larger the current, the faster the operation. CAUTION
Therefore, the motor is allowed to carry a small overload
USE THIS FEATURE IN AN
current. The relay can be set to trip at a current well
EMERGENCY ONLY. DO NOT USE IT
below the stalled rotor current because the time delay
OTHERWISE.
gives the motor time to accelerate to full speed before
the relay operates. By this time the current will have
dropped to full-load current, which is well below the There are three methods of providing an emergency
relay trip setting. run in magnetic controllers-an emergency run push

6-18
button, a reset-emergency run lever, or a
start-emergency run pushbutton. In each of these types,
the lever or push button must be held closed manually
during the entire emergency.
Figure 6-26 is a schematic diagram of a controller
showing a separate EMERGENCY RUN push button
with normally open contacts in parallel with the
normally closed contact of the overload relay. (NOTE:
Like all schematics, this one uses standard symbols to
show the electrical location and operating sequence of
the individual elements or devices, and it does not
indicate their relative physical location.) For
emergency run operation, the operator must hold down
this push button and press the START button to start the
motor. While the emergency run push button is
depressed, the motor cannot be stopped by opening the
overload relay contact.

A RESET-EMERGENCY RUN lever is shown in

figure 6-27. As long as the lever or rod is held down, Figure 6-27.—Schematic of controller with reset-emergency
lever or rod.
the overload relay contact is closed. The start button
must be momentarily closed to start the motor. Figure
6-28 shows a START-EMERGENCY RUN push button. marked start-emergency run should not be kept closed
The motor starts when the button is pushed and for more than a second or two unless the emergency run
continues to run without overload protection as long as operation is desired.
it is held down. For this reason, push buttons that are
Manual controllers may also be provided with an
emergency run feature. The usual means is a
start-emergency run push button or lever, which keeps
the main contactor coil energized despite the tripping
action of the overload relay mechanism.

Figure 6-26.—Schematic of controller with emergency run Figure 6-28.—Schematic of controller with start-emergency
push button. run push button.

6-19
SHORT-CIRCUIT PROTECTION mechanical parts to stick and, if allowed to go
unchecked, can lead to a short circuit between contacts.
Overload relays and contractors are usually not
The controller should be cleaned periodically, per
designed to protect motors from currents greater than
PMS requirements, to remove dust and dirt from the
about six times the normal rated current of ac motors or
enclosure. Contact surfaces should be kept free of dirt,
four times normal rated current of dc motors. Since
grease, and grime. Seating surfaces of magnetic cores
short-circuited currents are much higher, protection and armatures should be kept free of grease and scale to
against short circuits in motor controllers is obtained ensure quiet operation and a good seal of magnetic parts.
through other devices. To protect against short circuits,
circuit breakers are installed in the power supply system, Use of compressed air in cleaning is not
thereby protecting the controller, motor, and cables. recommended since it could blow metallic dust particles
Short-circuit protection is provided in controllers where with such force as to pierce insulation or cause short
it is not provided by the power distribution system. circuits.
Also, short-circuit protection isn’t provided where two
or more motors are supplied power, but the circuit INSULATION
breaker rating is too high to protect each motor
separate] y. Short-circuit protection for control circuits Insulation of the contractors, wiring, switches, and
is provided by fuses in the controller enclosure, which so forth, should be inspected periodical y to ensure there
provides protection for remote push buttons and is no danger of fire or electric shock. A convenient way
pressure switches. to schedule the maintenance is to accomplish the checks
at the same time as the maintenance checks for the motor
FULL-FIELD PROTECTION it serves. Doing a check in this way prevents the need
to de-energize the motor and controller more than once,
Full-field protection is required when a shunt field which allows the system to stay on line with as few
rheostat or a resistor is used to alter a dc motor field and interruptions as possible.
obtain different motor speeds. Full-field protection is
provided automatically by a relay that shunts out the shunt LUBRICATION
field rheostat for the initial acceleration of the motor,
and then cuts it into the motor field circuit. In this way, The only lubrication that might be necessary is the
the motor first accelerates to 100 percent or full-field application of light oil to hinge pivots of contractors that
speed, and then further accelerates to the weakened- don’t operate freely and mechanical interlock
field speed determined by the rheostat settings. mechanisms.

JAMMING (STEP BACK) PROTECTION

CONTROLLER
TROUBLESHOOTING
The controller for an anchor windlass motor
provides stepback protection by automatically cutting Although the Navy maintains a policy of preventive
back motor speed when needed to relieve the motor of maintenance, sometimes trouble is unavoidable. In
excessive load. general, when a controller fails to operate or signs of
trouble (such as heat, smoke, smell of burning
insulation) occur, the cause of the trouble can be found
CONTROLLER MAINTENANCE
by conducting an examination that consists of nothing
Controllers only operate correctly when serviced by more than using the sense of feel, sight, and sound. On
a planned program of periodic maintenance and other occasions, however, locating the cause of the
inspection. Since controllers frequently operate several problem will involve more detailed actions.
times a day, they should be inspected and serviced
Troubles tend to gather around mechanical moving
regularly so that normal repairs or replacement of parts
parts and where electrical systems are interrupted by the
can be accomplished before a failure occurs.
making and breaking of contacts. Center your attention
in these areas. See table 6-10 for a list of common
CLEANING
troubles, their causes, and corrective actions.

Dust should not be allowed to accumulate inside the When a motor-controller system has failed and
controller. An excessive amount of dust can cause pressing the start button will not start the system, press

6-20
Table 6-10.—Troubleshooting Chart

6-21
Table 6-10.—Troubleshooting Chart-Continued

6-22
the overload relay reset push button. Then attempt to controller circuit must be checked for possible fault. As
start the motor. If the motor operation is restored, no you read this section, refer to figures 6-29 and 6-30.
further checks are required. However, if you hear the
Remove the controller line fuses or verify that the
controller contacts close but the motor fails to start, then
fuses are removed. Danger tag the controller line fuses
check the motor circuit continuity. If the main contacts
that have been removed and taking the applicable
don’t close, then check the control circuit for continuity.
electrical safety precautions according to NSTM,
An example of troubleshooting a motor-controller
electrical system is given in a sequence of steps that may chapter 300, check the controller de-energized.
be used in locating a fault: Using an ohmmeter, check the continuity of the
1. Symptom recognition-recognize the normal control circuit between the L1 and the L3 connection
operation of the equipment points (point A and B of fig. 6-30) in the controller while
holding the start button in the START position. If the
2. Symptom elaboration-recognize/observe the
control circuit is good, the ohmmeter should read a
faulty operation of the equipment
resistance equivalent to the resistance value of the
3. Listing of probable faulty functions-develop a contactor coil. Depending on the size of the coil, this
list of possible causes for the malfunction value could be anywhere from a couple hundred ohms
4. Localizing the fault-determine the most likely to a couple thousand ohms. If the ohmmeter reading is
areas of failure to create the symptoms noted infinite, the problem is in the control circuit.

5. Localizing the trouble to the circuit-using test To isolate the fault in the control circuit, leave one
equipment, isolate the malfunction down to the of the ohmmeter leads on the L1 control circuit
most likely component(s) connection point (point A) and move the other lead of
6. Failure analysis-verify the component(s) is/are the ohmmeter to the other side of the contactor coil in
faulty the controller (point C). If while holding the start button
in the ON position the ohmmeter reads infinite, the fault
Let’s start by analyzing the power circuit.
is between point A and C in the control circuit. If the
POWER CIRCUIT ANALYSIS

When no visual signs of failure can be located and

an electrical failure is indicated in the power circuit, you
must first check to see if power is available and the line
fuses are good. See if the supply source is available by
checking that the feeder breaker is shut and other
equipment receiving power from that breaker is
operational. Only under extremely rare situation would
there be a break in the cabling going to the line fuses.
Taking applicable electrical safety precautions
according to NSTM, Chapter 300, remove the line fuses
and check the continuity of the fuses. While removing
the fuses, check for lose fuse clips which could give a
faulty connection to the line fuse. If power is available
and the line fuses are good, then the problem is in either
the control circuit, the motor line leads, or the motor
itself.

CONTROL CIRCUIT ANALYSIS

Taking applicable electrical safety precautions

according to NSTM, chapter 300, remove the control
fuse and check the fuse continuity. If the fuse is bad,
replace the fuse with a fuse of proper size and rating and
retest the controller. If the control fuse is good, the Figure 6-29.—Typical three-phase controller.

6-23
 If the control circuit continuity check was of a
satisfactory value, the problem is in either the lines to
the motor, the motor, or the main contacts of the
contactor. Check the main contacts of the contactor by
manually operating the contactor and reading the
continuity across the main contacts.

If the main contacts of the contactor read good,

check the lines leading to the motor and the motor
windings themselves. You do this by measuring the
motor winding resistance between the T1 and T2 and T3
points in the controller. If there is a high or infinite
reading at this point, isolate the fault to the motor or lines
leading to the motor by reading the motor winding
resistance in the terminal connection box on the motor.
A good resistance value indicates the fault in the lines
to the motor. A high or inifinite value indicates the fault
is in the motor.

When starting a three-phase motor and the motor

fails to start and makes a loud hum, you should stop the
motor immediately by pushing the stop button. These
symptoms usually mean that one of the phases to the
motor is not energized. You can assume that the control
circuit is good since the main contactor has operated and
the maintaining contacts are holding the main operating
contactor in. Look for trouble in the power circuit
(controller line fuses, main contacts, overload heaters,
cable, and motor).

SUMMARY
Figure 6-30.—Troubleshooting a thee-phase magnetic line
starter. In this chapter you were introduced to the
fundamentals of the various ac and dc motor and circuit
ohmmeter reads close to zero, the fault is in the contactor control devices to enable you to maintain, troubleshoot,
coil. and repair the equipment successfully. Almost all
equipment installed will have a manufacturer’s
By maintaining the one ohmmeter lead on the L1 technical manual that should be used to adjust and repair
control circuit connection point in the controller (point the equipment following the recommended
A) and moving the other ohmmeter lead along the specifications. The NSTM, chapter 302, will provide
control circuit (points D then E then F) towards the first additional information of value to you so that your
ohmmeter lead, you will localize the fault to a faulty electrical plant will be maintained in the highest state of
component or lead. readiness.

6-24
 CHAPTER 7

MAINTENANCE AND REPAIR

OF ROTATING ELECTRICAL
MACHINERY

The main objective of shipboard preventive ventilation ducts and increase resistance to the
maintenance is the preventing the breakdown, dissipation of heat, causing local or general overheating.
deterioration or the malfunction of equipment. If this If the particles form a conducting paste through the
objective is not met, failed equipment must be repaired absorption of moisture or oil, the motor or generator
or replaced. By performing preventive maintenance
windings may eventually be short-circuited or
according to the prescribed procedures, you can ensure
grounded.
proper operation of the equipment in the ship’s electric
plant. However, despite your best efforts, on occasion Additionally, abrasive particles may puncture
corrective action will be required to restore the electric insulation; iron dust is particularly harmful since the
plant to peak operating conditions. This chapter dust is agitated by magnetic pulsations. The acceptable
describes maintenance practices and procedures for methods of cleaning motors and generators involve the
preventing casualties to, and for diagnosing, repairing,
use of wiping rags or cloths, suction, low-pressure air,
and testing shipboard electric motors and generators.
and solvents. Wiping with a clean, lint-free, dry rag
For additional information, refer to Naval Ships’
(such as cheesecloth) is effective for removing loose
TechnicalManual (NSTM), chapters 300, 302, and 310,
and Naval Sea Systems Command Technical Manual, dust or foreign particles from accessible parts of a
0900-LP-060-2010, “Electric Motor Repair.” machine. When wiping, do not neglect the end
windings, mica cone extensions at the commutator of dc
LEARNING OBJECTIVES machines, slip-ring insulation, connecting leads, and
terminals.
Upon completion of this chapter, you will be able to
do the following: The use of suction is preferred to the use of
compressed air for removing abrasive dust and particles
1. Identify the procedures to be followed in
cleaning motors and generators. from inaccessible parts of a machine because it lessens
the possibility of damage to insulation. If a vacuum
2. Identify various types of bearings and their
cleaner is not available for this purpose, a flexible tube
proper care.
attached to the suction side of a portable blower will
3. Describe the procedures for maintaining and make a suitable vacuum cleaner. Always exhaust the
overhauling commutators and collector rings. blower to a suitable sump or overboard. Whenever
4. Describe the steps to be followed in overhauling possible, remove grit, iron dust, and copper particles by
and rewinding dc machines and armatures. suction methods.
5. Describe the methods of overhauling and Clean, dry, compressed air is effective in removing
rewinding ac machines.
dry, loose dust and foreign particles, particularly from
6. Describe the operation of motor and generator inaccessible locations such as air vents in the armature.
air coolers. Air pressure up to 30 pounds per square inch (psi) may
be used to blow out motors or generators. Where air
CLEANING ROTATING lines carry higher pressure than is suitable for blowing
ELECTRICAL MACHINERY out a machine, use a throttling valve to reduce the
One of your most important jobs is to keep all pressure. Always blow out any accumulation of water
electrical machinery clean. Dust, dirt, and foreign in the airlines before directing the airstream on the part
matter (such as carbon, copper, and mica) tend to block or machine to be cleaned.

7-1
 CAUTION the Navy. These bearings are further divided into the
following three types (fig. 7-1), depending on the load
Be careful when using compressed air, they are designed to bear:
particularly if abrasive particles are present
1. Radial. Radial bearings are capable of
because they may be driven into the insulation
supporting combined high radial and thrust
and puncture it or be forced beneath the
insulating tape. Compressed air should be used loads, but they aren’t self-aligning. Therefore,
only after the equipment has been opened on accurate alignment between the shaft and
both ends to allow the air and dust to escape. housing is required.
The use of compressed air will be of little 2. Angular contact. Angular contact bearings are
benefit if the dust is not suitably removed from designed to take radial and thrust loads where
the equipment. The most suitable method to the thrust component may be large.
remove dirt-laden air is to place a suction hose
on the opposite end of the equipment where 3. Thrust. Thrust bearings are used when the load
compressed air is being used is completely axial rather than radial.
The ball bearings on a rotating shaft of an electric
Whenever possible, avoid the use of solvents for motor or generator may be subjected to radial thrust
cleaning electrical equipment. However, their use is
and/or angular forces. While every ball bearing is not
necessary for removing grease and pasty substances
subjected to all three forces, any combination of one or
consisting of oil and carbon or dirt. Alcohol will injure
more may be found depending on the equipment design.
most types of insulating varnishes, and it should not be
used for cleaning electrical equipment. Because of their Radial loads are the result of forces applied to the
high toxicity, solvents containing gasoline, benzene, and bearing perpendicular to the shaft; thrust loads are the
carbon tetrachloride must NEVER be used for cleaning result of forces applied to the bearing parallel to the
purposes. Refer to chapter 1 of this manual and NSTM, shaft; and angular loads are the result of a combination
chapter 300, for detailed information on the use of of radial and thrust loads. The load carried by the
solvents for cleaning electrical machinery. bearings in electric motors and generators is almost
entirely due to the weight of the rotating element. For
Motors, generators, and other electrical equipment
this reason, the method of mounting the unit is a major
that have been wet with salt water should be flushed out
factor in the selection of the type of bearing installed
with fresh water and dried. Never let the equipment dry
before flushing it with fresh water. For complete when they are constructed. In a vertically mounted unit,
information on washing and drying procedures, refer to the thrust bearing is used, while the radial bearing is
NSTM, chapter 300. normally used in most horizontal units.

BEARINGS
Bearings are designed to allow a rotating armature
or rotor to turn freely within a motor or generator
housing. Shaft bearings must be properly maintained to
reduce the heat caused by friction.

The two common types of bearings found in motors

and generators are antifriction bearings and friction
bearings.

ANTIFRICTION BEARINGS

There are two types of antifriction bearings—ball

and roller. Basically, both types consist of two hardened
steel rings, hardened steel rollers or balls, and
separators. The annular, ring-shaped ball bearing is the
type of roller bearing used most extensively in the
construction of electric motors and generators used in Figure 7-1.—Representative types of ball bearings.

7-2
Wear of Bearings

Normally, it is not necessary to measure the air gap

on machines with ball bearings because the construction
of the machines ensures proper bearing alignment.
Additionally, ball bearing wear of sufficient magnitude
as to be readily detected by air-gap measurements would Figure 7-2.—Checking motor or generator shaft. (A) Vertical
movements: (B) End-play movement.
be more than enough to cause unsatisfactory operation
of the machine. Lubrication

The easiest way of determining the extent of wear A common cause of motor and generator failure is
in these bearings is to periodically feel the bearing overlubrication. Forcing too much grease into the
housing while the machine is running to detect any signs bearing housing seals and onto the stationary windings
of overheating or excessive vibration, and to listen to the and rotating parts of the machine will cause overheating
bearing for the presence of unusual noises. and deterioration of insulation, eventually resulting in
Rapid heating of a bearing maybe an indication of electrical grounds and shorts. Overheating will also
cause rapid deterioration of the grease and the eventual
danger. Bearing temperatures that feel uncomfortable
destruction of a bearing. To avoid overlubrication, add
to the touch could be a sign of dangerous overheating,
but not necessarily. The bearing may be operating new lubricant only when necessary.
properly if it has taken an hour or more to reach that The frequency that new grease must be added
temperature; whereas, serious trouble can be expected depends on the service of the machine and the tightness
if high temperatures are reached within the first 10 or of the housing seals, and the requirements should be
15 minutes of operation. determined for each machine by the engineering officer
or PMS requirements. A large quantity of grease
The test for excessive vibration relies to a great
coming through the shaft extension end of the housing
extent on the experience of the person conducting the
usually indicates excessive leakage inside the machine.
test. The person should be thoroughly familiar with the
normal vibration of the machines to be able to correctly To prevent greasing by unauthorized personnel,
detect, identify, and interpret any unusual vibrations. grease cups are removed from motors and generators.
Vibration, like heat and sound, is easily telegraphed. A Pipe plugs are inserted in place of the grease cups. The
thorough search is generally required to locate the pipe plugs are replaced temporarily with grease cups
source and determine its cause. during lubrication (fig. 7-3). (Removable grease cups

Ball bearings are inherently more noisy in normal

operation than sleeve bearings (discussed later). This
fact must be kept in mind by personnel testing for the
presence of abnormal bearing noise. A common method
for sound testing is to place the blade of a screwdriver
against the bearing housing and the handle against the
ear. If a loud, irregular grinding, clicking, or scraping
noise is heard, trouble is indicated. As before, the
degree of reliance in the results of this test depends on
the experience of the person conducting the test.

Checking the movement of a motor or generator

shaft can also give an indication of the amount of
bearing wear. If the motor shaft has excessive vertical
movement (fig. 7-2, view A), it indicates worn bearings.
Figure 7-2, view B, shows how to get a rough
approximation of motor or generator end-play
movement. You can correct excessive end-play, as
described in the applicable technical manual, by adding
bearing shims. Figure 7-3.—Grease-lubricated ball bearings.

7-3
should remain in the custody of the responsible RENEWAL OF GREASE WITHOUT
maintenance personnel.) Make sure the grease cups are DISASSEMBLING THE BEARING HOUSING.—
clean. After the grease is added, clean the pipe plugs Do not try to add new grease without at least partially
before replacing them. disassembling the bearing housing unless the following
The preferred method of adding grease calls for conditions exist:
disassembly of the bearing housing. Although not • The machine is horizontal. There is no adequate
recommended, renewing the bearing grease without at means of protecting the windings against
least partially disassembling the housing may be tried displaced lubricant in vertical machines.
under certain conditions (given later).
• A suitable fitting is provided for admitting
RENEWAL OF GREASE BY DIS- grease. If a grease-gun fitting is provided, it
ASSEMBLING THE BEARING HOUSING.— The should be replaced by a grease cup when you add
extent of disassembly necessary will depend on the grease.
construction of the bearing, Bearings with outer bearing
caps should be disassembled as described in table 7-1: • The drain hole on the bearing housing is
accessible. Drainpipes do not permit satisfactory
Table 7-1.—Renewal of Grease by Disassembly of the Bearing escape of displaced grease, and should be
Housing
removed when renewing grease.
• The machine is running continuously while
removing grease. If the machine cannot be run
continuously during the greasing period without
injuring the driven auxiliary or endangering
personnel, the bearing housing must be
disassembled to renew the grease.
If one or more of the above conditions exist, renew
the grease in assembled bearing housings by the method
in table 7-2:
Table 7-2.—Renewal of Grease in Assembled Bearing Housings

7-4
Oil-Lubricated Ball Bearings
Lubrication charts or special instructions are
generally furnished for electric motors and generators
equipped with oil-lubricated ball bearings. The oil level
inside the bearing housing should be maintained about
even with the lowest point of the bearing inner ring. At
this level, there will be enough oil to lubricate the
bearing for its operating period, but not enough to cause
churning or overheating.

One common method by which the oil level is

maintained in ball bearings is the wick-fed method In
this method, the oil is fed from an oil cup to the inside
of the bearing housing through an absorbent wick. This
Figure 7-4.—Wkk-fed bell bearings.
wick also filters the oil and prevents leakage through the
cup if momentary pressure is built up within the are prelubricated. Cleaning will remove the lubricant
housing. A typical wick-fed, oil-lubricated ball bearing from the bearings or can dilute the lubricant until it no
is shown in figure 7-4. longer possesses its original lubricating qualities.

Grease-Lubricated Ball Bearings Permanently lubricated ball bearings require no

greasing. You can recognize equipment furnished with
Preferred Navy bearing greases for shipboard these bearings by the absence of grease fittings or the
auxiliary machinery are as follows: provision for attaching grease fittings. When
1. Bearings operating below 110°C (230°F) in permanently lubricated bearings become imperative,
non-noise or noise-critical application should use replace them with bearings of the same kind. If not
DOD-G-24508 grease. It is available in a 1-pound can already provided, attach DO NOT LUBRICATE
under National Stock Number (NSN) nameplates to the bearing housing of machines with
9150-00-149-1593. sealed bearings.

2. Bearings operating near water (for example, Cleaning Bali Bearings

rudder stock bearings) should use grease MIL-G-24139. You can clean an open or a single-sealed ball
It is available in a 5-pound can under NSN bearing only in an emergency when a suitable replace-
9150-00-180-6382. ment is not available. It is difficult to remove dirt from
NOTE: Other size containers may be available ball bearings. Unless the cleaning is carefully done,
under other NSNs. more dirt may get into the bearings than is removed

DOUBLE-SHIELDED OR DOUBLE-SEALED In cleaning an open, single-shielded or single-

BALL BEARINGS SHOULD NEVER BE sealed bearing, take the bearing off with a bearing puller
DISASSEMBLED OR CLEANED. These bearings applied to the inner race of the bearing. Figure 7-5,

Figure 7-5.—Bearing pullers.

7-5
views A and B, shows two types of bearing pullers, both
of which apply the pulling pressure to the inner race of
the bearing. Removal of bearings by pulling on the outer
race tends to make the balls dent the raceway even when
the puller is used. If bearings are subjected to high
temperatures, the race can be distorted. This can cause
the race to shrink to the shaft more tightly. You should
be careful not to damage the shaft when removing
bearings. Use soft centers (shaft protectors), which are
sometimes provided with a bearing removal kit. If not,
the soft centers may be made of soft metal, such as zinc
or brass.
After removal, thoroughly clean the bearing. The
recommended cleaner is standard solvent or clean oil.
Soak the bearing in cleaner for as long as necessary to
dislodge dirt or caked grease from around the balls and
separators. After the bearing is cleaned, wipe it
carefully with a dry, lint-free cloth. If compressed air is Figure 7-6.—Removing seized outer ring of bearing.
used for drying, direct the airstream across the bearing
so that the bearing does not spin. Because a dry bearing 1. Don proper safety equipment (goggles,
rusts quickly, protect the bearing at once by coating it earmuffs, gloves, etc.)
with clean, low-viscosity lubricating oil.
2. Use clean rags or plastic drapes to protect any
Rotate the inner ring slowly by hand, and if the equipment nearby from flying bits of debris and
bearing feels rough, repeat the cleaning. After the
metal particles.
second cleaning, if the bearing still feels rough when
turned slowly by hand, renew it. 3. Using a high-speed grinder with a cutting wheel,
cut the outer ring of the seized bearing in two
Removing a Seized Bearing places (fig. 7-6).

When a bearing fads on equipment that is running, 4. Remove the outer rings and discard.
it is not always possible to secure the equipment 5. Cut the cage in two places and remove the cage
immediately. This may cause one or both of the and balls.
bearings to heat excessively and seize to the shaft.
Removal of a seized bearing may be accomplished as 6. Make two cuts to the inner ring at two different
follows: points as illustrated in figure 7-7. Be careful to

Figure 7-7.—Removing seized inner ring of bearing.

7-6
 cut only 3/4 of the way through the seized inner method should not be used unless absolutely necessary.
ring in order to prevent damage to the shaft. The disadvantages of the hot-oil method are the lack of
temperature control, the possibility of bearing
7. Using the correct size chisel, as shown in figure
enlargement and grease deterioration or contamination
7-8, crack the bearing inner ring and remove it.
by dirty oil.

Bearing Installation For additional methods of bearing installation, refer

to NSTM, chapter 244.
There are two acceptable methods for installing
bearings-the arbor press method and the heat method. FRICTION BEARINGS

ARBOR-PRESS METHOD.— When available Friction bearings are of three types:

and adaptable, you can use an arbor press if you take the
proper precautions. Place a pair of flat steel blocks 1. Right line. In right line friction bearings, motion
under the inner ring or both rings of the bearing. Never is parallel to the elements of a sliding surface.
place blocks under the outer ring only. Then, lineup the 2. Journal. In journal friction bearings, two
shaft vertically above the bearing, and place a soft pad machine parts rotate relative to each other.
between the shaft and press ram. After making sure the
shaft is started straight in the bearing, press the shaft into 3. Thrust. In thrust bearings, any force acting in
the direction of the shaft axis is taken up.
the bearing until the bearing is flush against the shaft or
housing shoulder. When pressing a bearing onto a shaft, Turbine-driven, ship’s service generators and
always apply pressure to the inner ring; when pressing propulsion generators and motors are equipped with
a bearing into a housing, always apply pressure to the journal bearings, commonly called sleeve bearings. The
outer ring. bearings may be made of bronze, babbitt, or
steel-backed babbitt. Preventive maintenance of sleeve
HEAT METHOD.— A bearing can be heated in an
bearings requires periodic inspections of bearing wear
oven or furnace to expand the inner ring for assembly.
and lubrication.
This method ensures uniform heating all around the
bearing.
Wear of Bearings
Heat the bearing in an infrared oven or a
temperature-controlled furnace at a temperature not to Propulsion generators, motors, and large ship’s
exceed 203° ± 10°F (89.4° to 100.6°C). The bearing service generators are sometimes provided with a gage
should be left in the oven or furnace only for enough for measuring bearing wear. You can obtain bearing
time to expand the inner race to the desired amount. wear on a sleeve-bearing machine not provided with a
Prolonged heating could possibly deteriorate the bearing by measuring the air gap at each end of the
prelubrication grease of the bearing. The bearing may machine with a machinist’s tapered feeler gage. Use a
also be heated in oil at 203° ± 10°F (89.4° to 100.6°C) blade long enough to reach into the air gap without
until expanded, and then slipped on the shaft. This removing the end brackets of the machine. Before

Figure 7-8.—Cracking seized inner ring of bearing.

7-7
making the measurements, clean the varnish from a spot check by feeling the bearing housing whenever possible.
on a pole or tooth of the rotor. A spot should also be Operating personnel must thoroughly familiarize
cleaned at the same relative position on each field pole themselves with the normal operating temperature of
of a dc machine. For ac machines, clean at least three each bearing so they will be able to recognize any
and preferably four or more spots spaced at equal sudden or sharp changes in bearing oil temperature.
intervals around the circumferences on the stator. Take Many large generators are provided with bearing
the air gap measurement between a cleaned spot on the temperature alarm contractors, which are incorporated in
rotor and a cleaned spot on the stator, turning the rotor the ship’s alarm system. The contactor is preset to
to bring the cleaned spot of the rotor in alignment with provide an alarm when the bearing temperature exceeds
the cleaned spots on the stator. Compare these readings a value detrimental to bearing life. You should secure
with the tolerance stated by the manufacturer’s the affected machinery as soon as possible if a bearing
instruction book. malfunction is indicated. A motor with overheated
sleeve bearings should be unloaded, impossible, without
Oil Rings and Bearing Surfaces stopping the motor. If you stop it immediately, the
bearing may seize. The best way to limit bearing damage
An opening is provided in the top of the bearing for is to keep the motor running at a light load and supply
you to check the condition of the oil rings and bearing plenty of cool, clean oil until the bearing cools down
surfaces (fig. 7-9). Periodic inspections are necessary
Because the permissible operating temperature is
to make certain that the oil ring is rotating freely when
often too high to be estimated by the sense of touch,
the machine is running and is not sticking. With the
temperature measurements should be taken to determine
machine stopped, inspect the bearing surfaces for any
whether a bearing is overheated. A thermometer
signs of pitting or scoring.
securely fastened to the bearing cover or housing will
usually give satisfactory bearing temperature
Trouble Analysis
measurements on machines not equipped with bearing
temperature measuring devices. Do not insert a
The earliest indication of sleeve bearing
thermometer into a bearing housing, as it may break
malfunction normally is an increase in the operating
and necessitate disassembly of the machinery to remove
temperature of the bearing. Thermometers are usually
broken glass and mercury.
inserted in the lubricating oil discharge line from the
bearing as a means of visually indicating the Any unusual noise in operating machinery may also
temperature of the oil as it leaves the bearing. indicate bearing malfunction. When a strange noise is
Thermometer readings are taken hourly on running heard in the vicinity of operating machinery, make a
machinery by operating personnel. However, a large thorough inspection to determine its cause. Excessive
number of bearing casualties have occurred in which no vibration will occur in operating machinery with faulty
temperature rise was detected in thermometer readings; bearings, and inspections should be made at frequent
in some cases, discharge oil temperature has actually intervals to detect the problem as soon as possible.
decreased. Therefore, after checking the temperature at
the thermometer, personnel should make a follow-up
BRUSHES

Carbon brushes used in electric motors and

generators are generally constructed of one or more
plates of carbon, riding on a commutator, or collector
ring (slip ring), to provide a passage for electrical
current to an internal or external circuit. The generic
term, carbon brush, is used b y convention to denote all
brush compositions in which carbon is employed in
some proportion in one of its many structural forms,

The brushes are held in position by brush holders

mounted on studs or brackets attached to the
brush-mounting ring, or yoke. The brush holder studs,
or brackets, and brush-mounting ring comprise the
Figure 7-9.—Diagram of an oil-lubricated bearing. brush rigging. The brush rigging is insulated from, but

7-8
attached to, the frame or one end bell of the machine. Use the grade of brush shown on the drawing or in
Flexible leads (pigtails) are used to connect the brushes
the technical manual applicable to the machine, except
to the terminals of the external circuit. An adjustable
spring is generally provided to maintain proper pressure where Naval Sea Systems Command instructions issued
of the brush on the commutator to effect good after the date of the drawing or technical manual (such
commutation. Atypical dc generator brush holder and as the instructions for brushes to be used in electric
brush-rigging assembly is shown in figure 7-10.
propulsion and magnetic minesweeping equipment
Brushes are manufactured in different grades to dictate otherwise. In such cases, follow the Naval Sea
meet the requirements of the varied types of service. The Systems Command instructions. Most of the brushes in
properties of resistance, ampere carrying capacity, shipboard service appear on the Qualified Products List
coefficient of friction, and hardness of the brush are
determined by the maximum allowable speed and load of as complying with one of six military grades (S, A, H, D,
the machine. G, and E). For propulsion and magnetic minesweeping
equipment, only one grade of brush specified by the
CORRECT BRUSH TYPE manufacturer is permitted. The restriction on brush
interchangeability is due to the vital nature of the
The correct grade of brush and correct brush
adjustment are necessary to avoid commutation trouble. machines involved.

Figure 7-10.—Brush holder and brush rigging assembly.

7-9
CARE OF BRUSHES

All brush shunts should be securely connected to the

brushes and the brush holders. Brushes should move
freely in their holders, but they should not be loose
enough to vibrate in the holder. Before replacing a worn
brush with a new one, clean all dirt and other foreign
material from the brush holder.

Replace old brushes with new brushes when the old

brushes meet the following criteria:

worn or chipped so they will not move properly

in their holders

damaged shunts, shunt connections, or hammer

clips

riveted connections or hammer clips and are

worn to within one-eighth inch of the metallic
part

tamped connections without hammer clips, and

are worn to one-half or less of the original length Figure 7-11.—Measuring brush tension.
of the brush; or
divided by the contact area maybe considered to be the
spring-enclosed shunts and are worn to 40
spring operating pressure.
percent or less of the original length of the brush
(not including the brush head, which fits into one The toes of all brushes of each brush stud should
end of the spring). line up with each other and with the edge of one
Where adjustable brush springs are of the positive commutator segment.
gradient (torsion, tension, or compression) type, adjust The brushes should be evenly spaced around the
them as the brushes wear to keep the brush pressure commutator. To check brush spacing, wrap a strip of
approximately constant. Springs of the coiled-band,
paper around the commutator and mark the paper where
constant-pressure type, and certain springs of the
the paper laps. Remove the paper from the commutator,
positive gradient type are not adjustable except by
cut at the lap, and fold or mark the paper into as many
changing springs. Adjust pressure following the
manufacturer’s technical manual. Pressures as low as equal parts as there are brush studs. Replace the paper
1 1/2 psi of contact area may be specified for large on the commutator, and adjust the brush holders so that
machines and as high as 8 psi of contact area may be the toes of the brushes are at the creases or marks.
specified for small machines. Where technical manuals
are not available, a pressure of 2 to 2 1/2 psi of contact
area is recommended for integral horsepower and
integral kilowatt machines. About twice that pressure
is recommended for fractional horsepower and
fractional kilowatt machines. To measure the pressure
of brushes operating in box-type brush holders, insert
one end of a strip of paper between the brush and
commutator; use a small brush tension gage (such as the
0- to 5-pound indicating scale) to exert a pull on the
brush in the direction of the brush holder axis, as shown
in figure 7-11. Note the reading of the gage when the
pull is just sufficient to release the strip of paper so that
it can be pulled out from between the brush and
commutator without offering resistance. This reading Figure 7-12.—Method of sanding brushes.

7-10
 Figure 7-13.—Detail of brush rigging with sandpaper in position.

AU brush holders should be the same distance from thoroughly clean the commutator and windings to
the commutator, not more than one-eighth inch, nor less remove all carbon dust.
than one-sixteenth inch. A brush holder must be free of
The use of a brush seater will further improve the
all burrs that might interfere with the free movement of
fit obtained by sanding. A brush seater consists of a
the brush in the holder. Burrs are easily removed with
mildly abrasive material loosely bonded into a stick
a fine tile.
about 5 inches long. To use a brush seater to seat the
brushes, install the brushes in the brush holders and start
SEATING the machine. Press a brush securely against the
commutator by using a stick of insulating material or by
Accurate seating of the brushes must be ensured increasing the brush spring tension to its maximum
where their surfaces contact the commutator. value. Touch the brush seater lightly to the commutator,
Sandpaper and a brush seater are the best tools to exactly at the heel of the brush (fig. 7-14), so that
accomplish a true seat (fig. 7-12). abrasive material worn from the brush seater will be
carried under the brush. You must hold the brush seater
Disconnect all power from the machine. You must behind each brush, applying the seater for a second or
take every precaution to ensure that the machine will not two, depending on brush size. Do not hold the seater
be inadvertently started before using sandpaper to seat steadily against the commutator because it will wear
the brushes. away too rapidly and produce too much dust. After
Lift the brushes to be fitted and insert (sand side up)
a strip of fine sandpaper (No. 1), about the width of the
commutator, between the brushes and the commutator.
With the sandpaper held tightly against the commutator
surface to conform with the curvature and the brushes
held down by normal spring pressure, pull the sandpaper
in the direction of normal rotation of the machine (fig.
7-13). When returning the sandpaper for another pull,
lift the brushes. Repeat this operation until the seat of
the brush is accurate. Always finish with a finer grade
of sandpaper (No. 0). You need a vacuum cleaner for
removing dust while sanding. After sanding, Figure 7-14.—Using the brush seater.

7-11
seating one or two brushes, examine them to see if the is applied, and the speed is again measured. When you
seater is being applied long enough to give a full seat. shift the brushes and the speed of the motor is the same
After seating the brush, if white dust is plainly visible in both directions, the brushes will be in the neutral
on the seat, you have applied insufficient pressure to the plain Generators are run at the same field strength and
brush, or applied the brush seater too heavily or too far the same speed in both directions, and the brushes are
from the brush. Be careful not to remove the copper shifted until the full-load terminal voltage is the same
oxide film from the commutator surface. If you remove for both directions of rotation. To ensure accuracy, you
this film, you must restore it, as described later in this must use a reliable tachometer to measure the speed of
chapter. the machines.

Use a vacuum cleaner during the seating operation

to prevent dust from reaching the machine windings and Inductive Kick Method
bearings. After seating all the brushes, blow out the
machine with a power blower or completely dry The kick method is used only when other methods
compressed air, or clean thoroughly with a vacuum are inadequate and the conditions are such as to warrant
cleaner. the risks involved. You must now connect sufficient
resistance in series with the field coils to reduce the field
SETTING ON NEUTRAL current to about 10 percent of normal value.

When a machine is running without a load and with With a lead pencil or other means that will not
only the main pole field windings excited,the point on damage the surface, mark A on a commutator bar under
the commutator at which minimum voltage is induced one set of brushes. Mark B on another bar one pole pitch
between adjacent commutator bars is the no-load neutral away from the center of the bar marked A. A pole pitch
point. This is the best operating position of the brushes is the angular distance from the center of one main pole
on most commutating-pole machines. Usually, the to the center of the next main pole. Raise all brushes.
brush studs are doweled in the proper position. The Connect bars A and B to a low-range voltmeter having
correct setting is indicated on a stationary part of the two or three scales (for example, 0 – 0.5, 0 – 1.5, or 0 –
machine by a chisel mark or an arrow. In some cases 15 volts). Use leads with pointed prongs to connect the
commutation may be improved by shifting the brushes bars. Separately excite the shunt field winding from a
slightly from the marked position. dc source connected to the winding in series with a high
resistance and a quick-break switch. Start with the
The three methods to determine the correct neutral
minimum obtainable value of field current and the
position are (1) mechanical, (2) reversed rotation, and high-range scale of the voltmeter.
(3) the inductive kick.
Close the knife switch and wait for the momentary
Mechanical Method deflection to disappear; open the knife switch and note
the momentary deflection or kick of the voltmeter. If
The mechanical method is an approximate method. insufficient deflection is observed on the lowest range
Turn the armature until the two coil sides of the SAME scale of the voltmeter, decrease the resistance connected
armature coil are equidistant from the center line of one in series with the shunt field winding and repeat the
MAIN field pole. The commutator bars to which the procedure until an adequate deflection is obtained on the
coil is connected give the position of the mechanical voltmeter when the switch is opened. Retain this setting
neutral. of the resistor for the remainder of the test. Turn the
armature slightly until the position is found at which the
Reversed Rotation Method minimum kick is produced when the field current is
broken. Bars A and B will then be on neutral. If one pole
Use of the reversed rotation method is possible only pitch from the center of bar A does not fall on a bar but
where it is practicable to run a machine in either on the mica between two bars, mark the bars next to the
direction of rotation, with rated load applied. This mica, C and D. Then measure the kick when bar A and
method differs for motors and generators. For motors, bar C are connected to the voltmeter, and again when A
the speed of the motor is accurately measured when the and D are connected to the voltmeter. Adjust the position
field current becomes constant under full load at line of the armature until these two deflections are equal and
voltage with the motor running in the normal direction. opposite. The center line of bar A and the mica between
Then, the rotation of the motor is reversed, the full load bars C and D will then be on neutral.

7-12
 COMMUTATORS AND COLLECTOR
RINGS (SLIP RINGS)

After being used about 2 weeks, the commutator of

a machine should develop a uniform, glazed,
dark-brown color on the places where the brushes ride.
If a nonuniform or bluish-colored surface appears,
improper commutation conditions are indicated.
Periodic inspections and proper cleaning practices will
keep commutator and collector-ring troubles at a
minimum.

CLEANING COMMUTATORS AND

COLLECTOR RINGS

One of the most effective ways of cleaning the

commutator or collector rings is to apply a canvas wiper
while the machine is running. You can make the wiper
by wrapping several layers of closely woven canvas
over the end of a strong stick between one-fourth and
three-eighths inch thick (fig. 7-15, view A). Secure the
canvas with rivets, and wrap linen tape over the rivets
to prevent the possibility of them coming in contact with Figure 7-15.—Cleaning commutator or collector rings.
the commutator. When the outer layer of canvas
becomes worn or dirty, remove it to expose a clean layer. paper, or emery stone on a commutator or collector ring
The wiper is most effective when it is used frequently. since the danger of causing electrical shorts exists.
On ship’s service generators, it may be desirable to use
the wiper once each watch. When using the wiper, TRUING COMMUTATORS AND
exercise care to keep from fouling moving parts of the COLLECTOR RINGS
machine. The manner of applying the wiper to a
commutator is illustrated in figure 7-15, view B.
With proper care and maintenance, commutators
When the machines are secured, you can use a and collector rings can be counted on to provide years
toothbrush to clean out commutator slots. You can use of carefree service. If not maintained properly,
a clean canvas or lint-free cloth for wiping the commutators and collector rings may be subject to any
commutator and adjacent parts. Besides cleaning by number of problems including excessive threading,
wiping, periodically clean the commutator with a grooving, copper drag, excessive out-of-roundness,
vacuum cleaner or blow it out with clean, dry air. waviness, high bars, high mica, slot or pitch patterns,
contaminated surface films, and so forth.
Do not sandpaper a commutator if it is operating
well, even if long service has developed threading, When any of these symptoms is encountered, the
grooving, pits, burn areas between bars, longitudinal most efficient and economical course of action usually
irregularities, etc., unless sparking is occurring or the is to begin corrective maintenance immediate y, rather
brushes are wearing excessively. In sanding a than wait for the condition to get worse. It is desirable,
commutator, use a fine grade of sandpaper (No. 0000 is however, to know the history of the machine before
preferred, but in no case coarser than No. 00). You can performing corrective maintenance. For example, light
use sandpapering to make emergency reduction of high threading, small pits, longitudinal irregularities or wide
mica or to polish finish a commutator that has been slots between bars made during undercutting usually
stoned or turned. The sandpaper, attached to a wooden indicate a need to resurface a commutator or collector
block shaped to fit the curvature of the commutator, is ring in place. However, if there is no sparking, brush
moved slowly back and forth across the surface of the wear is normal, and these abnormalities have developed
commutator while the machine is running at moderate over along period of time, no corrective action need be
speed. Rapid movement or the use of coarse sandpaper taken. Often, the best maintenance is to leave a well
will cause scratches. Never use emery cloth, emery running machine alone.

7-13
Collector Ring Circularity Sandpapering will not correct flat spots, grooves,
eccentricity, or out-of-roundness condition You can
The maximum total indicated runout (TIR) for correct some or all of these conditions by machine
collector rings is normally 0.001 inch to 0.002 inch. See stoning or handstoning, by turning on a lathe, or by
table 7-3 for eccentricity limits for various collector ring grinding with a rigidly supported stationary or revolving
diameters. Collector ring diameters are typically small stone. There are a number of grades of commutator
in comparison to commutators, and surface stones, from coarse to very fine, that cart be used for
irregularities accentuate brush motion more. Larger handstoning or grinding. Use the finest stone that will
commutators (18 inches in diameters) have do the job in a reasonable time. Do not use coarse
surface/brush interfacing that often allow excessive stones, as they tend to produce scratches that are hard to
out-of-roundness conditions without catastrophic remove. In turning or grinding commutators and
failure. collector rings, it is essential that the cut be parallel with
the axis of the machine; otherwise, a taper will result.
Commutator Circularity Do not disturb the commutator clamping bolts
unless the bars are loose (one or more high bars). Then
Ideally, commutator surfaces should be smooth and use a calibrated torque wrench and tighten only to the
mechanically true. Optimum perfomance is obtained values specified by the manufacturer’s instruction
if maximum runout of a commutator surface with manual for motors and generators. Make all other
respect to its center of rotation does not exceed 0.002 needed repairs, such as balancing, rebrazing armature
inches. This value is a judgment criterion and is connections, and repairing insulation faults, before
dependent upon the type of irregularity. Maximum truing the commutator.
allowable runout criteria could vary from less than 0.002
inches for wavy commutator surfaces to 0.005 inches After the commutator is trued (whether by stoning,
for elliptical surfaces. The type of irregularity and also grinding, or turning), finish with a fine grade of stone or
the degree of brush shunt fraying must be taken into sandpaper, undercut the mica, chamfer the commutator
consideration when evaluating the commutator surface bars (to be explained later in this chapter), clean the
condition. commutator and brush holders, and wipe off the brushes
with a clean, dry, lint-free cloth.
Corrective Action HANDSTONING.— Handstoning will remove flat
spots, grooves, scoring, and deep scratches; but, it will
Do not hue a commutator or collector ring in place not correct eccentricity, high bars, or an out-of-round
unless its condition has become so bad that it cannot wait condition. The machine should be running at, or slightly
until the next shop overhaul for reconditioning. Large below, the rated speed. Generators can normally be
commutators in the 125- to 850-rpm range, used on most turned by their prime movers; however, some
electric propulsion motors and generators, usually generators and motors must be turned by a pneumatic
operate satisfactorily with runouts up to 0.003 inch. or other prime mover.
Under no condition should you attempt to true a
commutator or collector ring in place unless there is The stone should be formed or worn to the curvature
of the commutator and should have a surface much
sparking, excessive brush wear, or brush movement
sufficient to fray the brush pigtails and wear the hammer larger than the largest flat spot being removed. Hold the
plates. Do not confuse brush chatter with brush stone in the hand and move it very slowly back and forth,
movement by runout. parallel to the axis of the surface. Do not press too hard
on the stone, just enough to keep it cutting. Being hasty
Table 7-3.—Collector Ring Eccentricity Limits or crowding the stone results in a rough surface and
possibly an out-of-round condition. Avoid jamming the
stone between the fixed and moving parts of the
machine.

MACHINE STONING.— Stoning should be done

by machine to correct eccentricity, high bars, or an
out-of-round condition. In one method of machine
stoning, a commutator dressing stone tool (fig. 7-16) is
mounted on the frame of the machine and holds a

7-14
 Figure 7-16.—Commutator dressing stone tool.

commutator stone against the commutator as the shock or fouling of moving parts whenever you are
armature is rotated. This method works for some of the grinding a motor commutator.
large open and driproof machines. Otherwise, the A commutator surface stone, when used, should be
armature must be removed from the machine and rigidly clamped in a holder and supported to keep the
mounted in a lathe and rotated. The commutator stone stone from chattering or digging into the commutator.
is mounted in the tool post and fed to the commutator, The support must provide for the axial motion of the
or a rotating precision grinder is mounted in the tool post stone. To prevent the commutator from having different
and the grinder wheel is fed to the commutator. diameters at both ends, you should never take heavy cuts
with a stone. Commutator surfacing stones with tool
GRINDING.— When practical, the armature
post handles are available in the Navy supply system in
should be removed from the machine and placed in a
various sizes and grades (such as free, medium, and
lathe for grinding. If not, the commutator can be ground
coarse).
in the machine, provided there is minimum vibration,
the windings can be adequately protected from grit, and In truing a commutator with a rotating grinder, use
suitable supports can accommodate the stone. a medium soft wheel so that the face will not fill up with
copper too rapidly. Even if the commutator is badly
When grinding the commutator in the machine, distorted, use a light cut, taking as many as needed. If
rotate the armature by using an external prime mover or, a heavy cut is used, the commutator maybe ground to a
in the case of a motor, by supplying power through just noncylindrical shape, although initial eccentricity may
enough brushes to take care of the load. You may use be retained because of the elasticity of the support. The
old brushes for this purpose since the y should be speed of the wheel should be that recommended by the
discarded after grinding. You should avoid electric manufacturer. The speed of the commutator should be

7-15
one-half to three-fourths the normal speed until most of brush performance and surface wear of the ring or
the eccentricity has been removed After this, the commutator.
commutator should be rotated at about normal speed.
The film itself is a composite of various constituents
LATHE TURNING.— When overhauling an adhering to both the surface and each other, including
armature in the shop, true the commutator by supporting copper oxides, graphite particles, and water vapor. This
it in a lathe, turning, and cutting (fig. 7-17). First make layer of film, although extremely thin (about 1-6
sure the armature shaft is straight and in good condition. molecules deep), provides sufficient separation between
With a diamond-point tool, cut only enough material to the brush and the ring to allow the brush to slide over
true the commutator. This tool should be rounded the surface with a minimum amount of wear to either.
sufficiently so that the cuts will overlap and not leave a
After the oxide film has been removed from the
rough thread on the commutator. The proper cutting
commutator surface by sandpapering, stoning, grinding,
speed is about 100 feet per minute, and the feed should
or turning, it is necessary to return the film before the
be about 0.10 inch per revolution. The depth of cut
machine is operated at or near full load.
should not be more than 0.010 inch. The reasons for a
light cut are the same as those for grinding. In addition, Before passing any current through the commutator
when you take a heavy cut, the turning tool tends to twist or collector ring, make sure the surface is mechanically
the commutator bars and cut deeper at one end than at smooth, and remove, with handbeveling tool, any sharp
the other. Do not remove small pits, bum spots between edges or slivers on the bar. When there are noticeable
bars, or other mechanical imperfections in the bars commutator scratches or roughness, use very fine
unless they interfere with the free sliding of the brushes. sandpaper (no coarser than No. 0000) to remove them.
Then burnish the ring using a commercial stone
After turning the commutator, finish it with a
(Military Specification MIL-S-17346). After
handstone and sandpaper. If balancing equipment is
burnishing, carefully brush any debris from between the
available, balance the entire rotating assembly before it
commutator bars. Before reinstalling a shop-
is reinstalled in the machine.
overhauled armature in its motor or generator, make
sure the commutator surface is smooth, the bar edges
SURFACE FILMS are leveled, and the spaces between the bars are clean.

The dark material that develops on the surface of Any commutator that has been resurfaced should
the commutator and collector rings is known as the undergo a seasoning process to restore its oxide film
surface film. Without film, satisfactory operation of the before being operated at or near full load. Start with a
sliding contact is impossible. The existence and 25 percent load and operate for 4 hours; then increase
condition of this film on the collector ring or the load by 10 percent increments every hour until full
commutator is a critical factor in determining proper load is reached To get the machine on full load in the
minimum time, run at 25 percent load for 3 hours, and
then increase the load by 15 percent every hour until full
load is reached. The shorter seasoning period is not
recommended unless the machine is urgently needed A
more in-depth study may be obtained in the
Commutator/Slip Ring Maintenance Handbook,
NAVSEA S9310-AC-HBK-010.

UNDERCUTTING MICA OF
COMMUTATORS

High mica or feather-edged mica may cause

sparking, a rough or uneven commutator surface,
streaking or threading, or other difficulties. Rough or
uneven commutator surfaces may also be caused if you
fail to chamfer the commutator segments after
undercutting. Tools are available for undercutting,
chamfering, and smoothing slot edges. Figure 7-18
Figure 7-17.—Truing a commutator by turning. shows a rotary, motor-driven tool for undercutting mica.

7-16
 Figure 7-19.—Undercutting mica with a hacksaw blade.

If a mica undercutter is not available, use hand tools

to cut the mica, as shown in figure 7-19. Do not use a
lubricant. Also, do not widen the commutator slots by
removing metal from the bars, nor leave a thin edge of
Figure 7-18.—Undercutting commutator mica with
undercutter. mica next to the bars.

After removing the high mica, smooth off all burrs.

The rotary cutters are either U- or V-shaped. The Then polish the commutator and test. Figure 7-20 shows
U-slots will give long wear and are best suited to examples of good and poor undercutting.
slow-speed machines or machines that operate in a clean
atmosphere and require little maintenance. The V-slots,
DISASSEMBLY AND REASSEMBLY
which are more quiet than U-slots, are better if dirt and
OF ROTATING ELECTRICAL
dust are present. The proper thickness for a U-shaped
MACHINERY
cutter is equal to the thickness of ± 0.001 inch. In
general, it is best not to cut U-shaped slots deeper than When you have to disassemble and reassemble a
one thirty-second of an inch, or, at most, three large motor or generator, follow the procedures outlined
sixty-fourths of an inch. The V-shaped slots are cut to a in the manufacturer’s instruction manual, exercising
depth that will remove some copper at the top. care to prevent damage to any part of the machine. The

Figure 7-20.—Example of good and poor undercutting.

7-17
 machine rotors should be supported, while being moved do more damage to a machine during disassembly and
or when stationary, by slings, blocking under the shaft, assembly than it will receive in years of normal service.
a padded cradle, or thickly folded canvas under the core
Figures 7-21 and 7-22 show typical ac and dc
laminations. When you are using rope slings to lift ac
or dc rotors, place them under the shaft, keeping them motors.
clear of the bearing journals. When construction of the Never be hasty or careless in disassembling a
rotors does not allow room, except around the bearing generator or motor. Handle the delicate components
journals, you must protect the surfaces with heavy paper
with care to prevent damage or create the need for
or canvas. Ensure rope slings never come in contact
additional adjustment. Use the proper tools, and label
with ac or dc rotor coils. When the complete unit (stator
and rotor) is to be lifted by lifting the starer, the bottom the parts as you dismantle them. Store them in an
of the air gap must be tightly shimmed unless both ends orderly arrangement in a safe place. Note the necessary
of the shaft are supported on the bearings. It is possible, information so that you will have no trouble in
by rough handling or careless use of bars or hooks, to reassembly.

Figure 7-21.—Typical ac motor.

7-18
Figure 7-22.—Typical dc Motor.

7-19
 If you have done a careful job of breaking down a
machine into its components, the process of reassembly
should be the reverse order of disassembly.

A few simple steps are to be taken when

disassembling a motor or generator:

1. Make sure you mark the frame and mating end

bells (fig. 7-23), using a different mark for each
end
2. When separating the end bells from the frame,
use a mallet or block of wood with a hammer
(fig. 7-24). Never pry mating surfaces apart with
a metal object such as a screwdriver.
3. To prevent damaging the brushes, lift them from
the commutator and/or slip rings before
removing the rotor.
4. Protect the windings by inserting thin strips of
waxed paper between the rotor and stator.
5. When using an arbor press to remove bearings, Figure 7-24.—Parting end bells with a hammer and a wood
take the proper precautions. (Place a pair of flat, block.
steel blocks under the inner ring or both rings of
the bearing. Never place blocks under the outer
ring only. Line up the shaft vertically above the into the bearing until the bearing is flush against
baring, and place a soft pad between the shaft the shoulder of the shaft). You may use a gear
and the press ram. After making sure the shaft puller to remove a rotor bearing, but take
is started straight in the bearing, press the shaft extreme care.
6. Never remove the bearings unless they are to be
replaced, or unless they must be removed to
allow the removal of the end bells.
7. If you are taking off a ball bearing and plan to
use it again, be careful to apply pressure to the
inner race only. If pressure has been applied to
the outer race, you will have to discard the
bearing.
8. Never use a cleaning solvent on a sealed or a
semi-sealed ball bearing. Store these bearings in
a clean piece of waxed paper until you are ready
to use them.
9. Clean the end bells with a brush and an approved
solvent. Check them for crocks, burrs, nicks,
excessive paint, and dirt.

TESTING COMPONENTS
OF ROTATING ELECTRICAL
MACHINERY

Preventive maintenance of armatures, rotors, or

Figure 7-23.—Marking a motor frame and end bell. windings consists mainly of periodic visual inspections
and electrical testing to determine the condition of the

7-20
equipment and proper cleaning practices to preserve the periodically for evidence of loose or fractured bars and
integrity of its insulation. Periodic testing and localized overheating.
inspection of the various electrical components of
Wound rotors (fig. 7-26) consist of wound coils
rotating electrical machinery will help to prevent
insulated from each other and laid in slots in the rotor
catastrophic failure of the equipment and leads to
core. These coils are wye-connected and terminate at
reduced overall maintenance cost of the equipment.
three slip rings.

AC MOTORS Wound rotors, like other windings, require periodic

inspections, tests, and cleaning. The insulation
AC motors comprise the majority of rotating resistance determines if grounds are present. An open
equipment to be maintained by the EM aboard ship. Of circuit in a wound rotor may cause reduced torque
the three general classes of ac motors in use today accompanied by a growling noise, or failure to start
(polyphase induction, polyphase synchronous, and under load. Besides reduced torque, a short circuit in
single-phase) the polyphase induction motor is, by far, the rotor windings may cause excessive vibration,
the most common used aboard ship. These motors are sparking at the brushes, and uneven collector ring wear.
well suited to shipboard use and can be counted on to With the brushes removed from the collector rings, a
operate for very long periods of time if maintained continuity check of the rotor coils will reveal the
according to prescribed PMS procedures. presence of a faulty coil.

Rotors
Stator Coils
Basically, the rotor of an ac motor is a squirrel-cage
rotor or a wound rotor. The squirrel-cage rotor usually The ac stator windings require the same careful
has heavy copper or aluminum bars fitted into slots in attention as other electrical windings. For a machine to
the rotor frame. These bars are connected to function properly, the stator windings must be free from
short-circuiting end rings by being cast, brazed, or grounds, short circuits, and open circuits.
welded together (fig. 7-25). In many cases, the cage
rotor is manufactured by die-casting the rotor bars, end A short circuit in the stator of an ac machine will
rings, and cooling fans into one piece. The cage rotor produce smoke, flame, or an odor of charred insulation.
requires less attention than the wound rotor since it is The machine must be secured immediately and tests
less susceptible to damage. The cage rotor, however, conducted to find the reason for the abnormal condition.
should be kept clean, and the rotor bars must be checked The first and easiest test that you should conduct is
to test the insulation resistance of the winding. This test
is made with a megohmmeter or similar
resistance-measuring instrument. Connect one
instrument lead to ground and the other to each motor
lead; crank the meter handle and read the scale on the
meter face. If the insulation resistance is within the

Figure 7-25.—Squirrel-cage rotor. Figure 7-26.—Wound rotor.

7-21
range specified in table 7-4, the stator is not grounded taken in soldering these leads because further damage
and other tests should be made to locate the trouble. could result if the coil leads are inadvertently shorted.
After accomplishing this emergency repair, test the
Next, test for continuity with an ohmmeter by
stator winding with a low voltage to ensure the correct
connecting the test leads to any two motor leads and then
phase balance.
to the next two leads, until all leads have been tested for
continuity between each other. Whether the motor is
Polyphase Stator Troubles
wye- or delta-connected, you should get nearly zero
indication on the ohmmeter between any two leads. A
The methods of locating and correcting the common
high resistance reading between any two leads is a good
troubles encountered in rewound and reconnected
indication of an open-phase winding.
polyphase stator windings are included for the
For your next check, determine whether or not time convenience of Electrician’s Mates engaged in this
are any mechanical difficulties, such as frozen bearings work.
or a frozen pump. First, disconnect the motor from the
SHORTED POLE-PHASE GROUP.— An entire
driven unit. Spin the motor shaft to see if it is free to
pole-phase group may be shorted in a polyphase stator.
turn. Then check the driven end for freedom of
Such a defect is usually indicated by excessive heat in
movement. If the driven end is frozen, you need check
the defective part. The trouble can be readily located by
no further. Inform the maintenance person responsible
a compass test. To conduct a compass test, excite the
for the driven end of your findings.
stator windings with a low-voltage, direct current that
A visual inspection of the stator will usually reveal will set up the poles in the stator (fig. 7-27). When the
where the trouble lies. If the stator windings are shorted windings are excited, a compass is moved around the
or have an open, the motor must be disassembled, inside circumference of the stator core. As each pole
rewound, and reassembled. If only one phase is open, group is approached, the polarity is indicated by the
it is possible to effect an emergency repair by carefully compass. There should be the same number of alternate
soldering the opened leads together. Care should be north and south poles in a three-phase winding.

Table 7-4.—Satisfactory Insulation Resistances for ac Motors and Generators (Other than Propulsion)

7-22
 will indicate about the same value of current for each of
the three phases. If one phase is shorted, the ammeter
will indicate a higher current reading for this phase than
those of the other two phases because the impedance is
less.
In testing a three-phase, delta-connected winding
(fig. 7-28, view B), open each delta connection and test
each phase separately. As in the wye-connected
winding, the shorted phase will be indicated by a much
higher current reading on the ammeter.
Figure 7-27.—Compass test for shorted pole-phase groups. OPEN CIRCUITS.— In testing a three-phase,
wye-connected winding (fig. 7-29, view A), connect the
In testing a three-phase, wye-connected winding ohmmeter leads across each of the phases to locate the
(fig. 7-27, view A), test each phase separately by defective phase. When the ohmmeter leads are placed
impressing the dc voltage successively on each of the on terminals A and C, no open circuit (a low reading) is
phase leads and the midpoint of the wye connectiom If indicated. However, when the leads are placed on
there is no trouble in the winding, the compass will terminals C and B and then on terminals B and A, an
indicate alternately north and south for each pole-phase open circuit (a high reading) is indicated in both
group around the stator. If a complete pole-phase group positions. This denotes an open in phase B. After the
is shorted, the compass needle will not be deflected at defective phase has been located, test each stub
this point. connection of the pole-phase groups with the ohmmeter
until the open coil is located.
In testing a three-phase, delta-connected winding
(fig. 7-27, view B), open one of the delta connections In testing a three-phase, deha-connected winding
and apply the direct current to the winding. The current (fig. 7-29, view B), open one delta connection to avoid
will flow through the three phases in series. If the shunting the phase being tested. Test each phase
pole-phase groups are connected properly, the compass separately until the open is located. After the faulty
will indicate alternate north and south poles around the phase is located, test each stub connection of the
stator frame. As in the wye-connected winding, a pole-phase groups, as in the wye connection, until the
shorted pole-phase group is indicated by no deflection open coil is located.
of the compass needle.
If the windings are parallel, open each parallel
SHORTED PHASE.— When an entire phase of a group and test each group separately.
three-phase winding is shorted, the defect is most
readily located by a balanced-current test made with a
DC MOTORS
type TA industrial analyzer. This test can also be made
with an ammeter and low-voltage ac source (fig. 7-28).
Though not as common as ac motors, dc motors are
In testing a three-phase, wye-connected winding still used in some applications aboard ship. Because
(fig. 7-28, view A), test each phase separately by brushes are used in these motors, they are more
impressing the ac voltage successively on each of the susceptible to damage caused by dust snd dirt than ac
phase leads and the midpoint of the wye connection. If motors. If allowed to accumulate, dust and dirt could
there is no trouble in the windings and if the impedance
of the winding of each phase is the same, the ammeter

Figure 7-28.—Balanced current test for shorted phase. Figure 7-29.—Ohmmeter test for open circuits.

7-23
create a path for current between insulated parts of the Armatures
motor and lead to a fire.
Frequent checks of the condition of the banding
Field Coils
wire that holds down the windings are necessary to
The insulation of the field coils should be tested determine if the wires are tight, undamagd, and have
periodically with a resistance-measuring device. If a not shifted. Also check the clips securing the wires to
ground is detected in the field circuits (shunt, series, and see that the solder has not loosened.
interpole) of a dc machine, you should disconnect all
You can detect some armature troubles while
circuits from each other and test separately to locate the
making inspections of running machines. Heat and the
grounded circuit. The coils in the circuit must be opened
odor of burning insulation may indicate a short-circuited
and tested separately to locate the grounded coil. It can armature coil. In a coil that has some turns shorted, the
then be repaired or replaced as necessary. resistance of one turn of the coil will be very low, and
When an open circuit develops in the field windings the voltage generated in that turn will cause a
of an ac or dc generator that is carrying a load, it will high-current flow. This results in excessive heating that
be indicated by the immediate loss of load and voltage. could cause the insulation to burn. If the armature is
An open in the shunt field winding of an operating dc readily accessible, you can detect the short-circuited coil
motor may be indicated by an increase in motor speed, immediately after stopping the machine because the
excessive armature current, heavy sparking, or stalling shorted coil will be much hotter than the others. In idle
of the rotor. When an open occurs in the field circuit of machines, you can identify a short-circuited coil by the
presence of charred insulation.
a machine, you must secure it immediately and examine
the circuit to locate the fault. An open circuit will usually An open armature coil in a running machine is
occur at the connections between the coils and can be indicated by a bright spark, which appears to pass
detected by visual inspection. The opening of an completely around the commutator. When the segment
energized field circuit induces a high voltage that can to which the coil is connected passes under the brushes,
damage the field insulation causing a safety hazard. the brushes momentarily y complete the circuit; when the

Table 7-5.—Satisfactory Insulation Resistance for dc Generators and Motors (except propulsion and auxlliary generators for
submarines) Including Exciters

7-24
 and burn out the winding. You can detect grounded coils
in idle machines by measuring insulation resistance (see
table 7-5). You can connect a Megger, or similar
insulation measuring device, to the commutator and to
the shaft or frame of the machine to properly measure
the resistance of the insulation of the coils.
You can make emergency repairs by cutting out a
short-circuited or open-circuited armature coil. This will
permit restoration of the machine to service until
permanent repairs can be made. However, permanent
repairs should be made as soon as possible. Cutout the
coil by disconnecting both ends of the coil and installing
a jumper between the two risers from which the coil was
disconnected. The coil itself is then cut at both the front
and rear of the armature to prevent overheating of the
damaged coil. A continuity test from one end to the back
of the coil will locate the turns of the faulty coil. If a pin
or needle is used to puncture the insulation for this test,
use insulating varnish to fill the tiny hole if the wrong
coil is pierced Insulate all conducting surfaces exposed
by the change in connection.s and tie all loose ends
securely to prevent vibration
Figure 7-30.—Classfifcation or armature windings. You must be able to identify various types of
armature windings to interpret trouble indications and
segment leaves the brushes, the circuit is broken, to make the necessary repairs.
causing a spark to jump the gap. The open will
eventually scar the commutator segments to which the LAP AND WAVE WINDINGS.— Armature
ends of the open coil are connected. windings, irrespective of how the elements are placed
on the armature core, are generally classified as LAP or
When a ground occurs in an armature coil of a WAVE windings. The classification designates the
running machine, it will cause the ground test lamps on method of connecting the ends of the elements, or coils,
the main switchboard to flicker on and off as the to the commutator. If the ends of the coil are connected
grounded coil segment passes from brush to brush to adjacent commutator segments or to segments that
during rotation of the armature. Two grounded coils will are close together, the coil is designated as a
act the same as a short circuit across a group of coils. lap-connected coil, and the winding is a lap winding
Overheating will occur in all of the coils in the group (figs. 7-30, view A, and 7-31, view A).

Figure 7-31.—Full-pitch coils.

7-25
 of a north pole, the right side of the same coil will occupy
a position under approximately the center of an adjacent
south pole. The distance between the centers of two
adjacent poles is the pole pitch. The span of one coil
should be equal or nearly equal to one pole pitch. If a
coil spans exactly one pole pitch, the winding is FULL
PITCH (fig. 7-31). If a coil spans less than one pole
pitch, the winding is FRACTIONAL PITCH. COIL
PITCH is recorded and identified by the number of slots
spanned by the coil in the armature (fig. 7-32).
NUMBERING.— The dc armature windings are
usually two-layer windings in which each slot contains
two coil sides of a single-coil type of winding (fig. 7-30).
One side of the winding element is placed in the top of
a slot and the other side is placed in the bottom of another
Figure 7-32.—Pole pitch.
slot. Either side of the element maybe placed in the top
PITCH.— Both lap and wave windings are placed or bottom of the slot. When you view the armature from
on the armature core so that the two sides of an element the commutator end, the right side of the coil is usually
occupy the slots that are influenced by adjacent poles of placed in the bottom of one slot, and the left side is
opposite polarity, and the emfs generated in the two placed in the top of another slot. The coils are arbitrarily
sides add together. In other words, if the left side of a numbered so that all TOP coil sides have odd numbers
coil momentarily occupies a position under the center and all BOTTOM coil sides have even numbers (fig.

Figure 7-33.—Meaning of coil pitch in armature winding.

7-26
7-30). This system helps to place the coils properly on MULTIPLEX WINDINGS.— Wmdings may also
the armature. be classified and connected in SIMPLEX, DUPLEX, or
TRIPLEX. A simplex lap winding is one in which the
PROGRESSIVE AND RETROGRESSIVE
beginning and ending leads of a lap-wound coil are
WINDINGS.— Lap and wave windings can be
connected to adjacent commutator bars. Duplex and
progressive or retrogressive, as shown in figure 7-33.
triplex lap windings have their leads connected two or
Progressive Windings.— A progressive winding three bars apart, respectively.
(fig. 7-33, view A) progresses in a clockwise direction
Progressive and retrogressive simplex lap windings
around the armature when traced through the winding
are shown in figure 7-34. In the progressive lap
from the commutator end. In other words, the winding
winding, the current flowing in the coil terminates in the
progresses clockwise from segment (bar) through the
commutator bar clockwise, adjacent to the starting bar,
coil to segment.
as you view the armature from the commutator end. In
Progressive wave windings and retrogressive lap a retrogressive simplex lap winding, the current in the
windings are very seldom encountered because of coil terminates in the bar counterclockwise, adjacent to
inherent undesirable features, such as the end the starting bar.
connections of coil groups crossing over each other,
Simplex progressive and retrogressive wave
added weight, and longer leads. Therefore, with few
windings are shown in figure 7-35. Compare these with
exceptions, lap windings are progressive and wave
windings are retrogressive. the lap windings shown in figure 7-34.

Retrogressive Windings.— A retrogressive TEST PROCEDURES. —Use of an organized test

winding (fig. 7-33, view B) progresses in a procedure will enable you to distinguish the types of
counterclockwise direction around the commutator armature windings. One method is to use a low-reading
when traced through the winding from the commutator ohmmeter (capable of reading minute ohmic values) to
end. indicate variations in the resistance reading as the test
probes are shifted around on the commutator. If a
low-reading ohmmeter is not available, a milliammeter

Figure 7-34.—Simplex lap windings. Figure 7-35.—Four-pole simplex wave windings.

7-27
 are about two pole pitches apart. Using the test
procedure described in the previous paragraph, the
maximum ammeter reading is indicated when the test
probes are connected across that portion of the winding
in which one coil shunts the remaining portion of the
winding. Hence, in all wave windings the maximum
Figure 7-36.—Test circuit for messuring armature resistance. reading will be indicated when the probes are placed on
commutator segments that are about two pole pitches
connected in series with a rheostat and a 6-volt battery apart. The minimum ammeter reading will occur when
can be used (fig. 7-36). the probes are placed on segments about one pole pitch
SIMPLEX LAP WINDING.— A schematic apart.
diagram of a simplex lap winding is illustrated in figure With one probe stationary on segment 1 (fig. 7-38)
7-37. With the test probes placed on adjacent segments, and the other probe moved around the commutator from
the ammeter should indicate a maximum because the segment to segment (2, 3, 4, and so forth), the ammeter
resistance of only one coil shunts the remainder of the readings should steadily decrease until the probes are
widing, and the resistance added to the test circuit is at about one pole pitch apart. Then the readings should
minimum. When one test probe is moved to the next steadily increase until the probes are about two pole
segment, the ammeter reading should decrease because pitches apart.
the resistance between the probes has increased. With
one probe stationary and the other probe contacting each If the probe is circled around the remainder of the
segment in succession around the commutator, the commutator, the readings should decrease and then
ammeter indications should decrease steadily until the increase once for each pair of poles. In the identification
test probes are directly opposite each other then the of a six-pole, simplex wave winding, there should be
indications start increasing steadily as the other half of three successive decreases and increases in the meter
the winding is tested. These indications are obtained readings. Thus, you can distinguish a simplex wave
because of the method of connecting the coils to the winding from a simplex lap winding by measuring the
commutator, which is determined by the type of resistances of the armature coils.
winding. A simplex lap winding is the only winding that
ARMATURE TESTING AND REPAIRING.—
gives these indications.
An armature is bench tested for grounds, opens, and
SIMPLEX WAVE WINDING.— An important shorts at disassembly to help determine the cause of the
rule to remember for all wave windings is that the ends dc motor or generator failure and the repairs that are
of each coil are connected to commutator segments that required.

Figure 7-37.—Schematic of a simplex lap winding. Figure 7-38.—Portion of a six-pole simplex wave winding.

7-28
 Figure 7-41.—Checking armature shorts with a growler.

milliammeter with a rheostat and a 6-volt battery, or a

Figure 7-39.—Testing an armature for grounds. growler.
An armature coil internally shorted within itself is
Locating armature grounds (fig. 7-39) may be done
determined with a growler. The growler (figs. 7-41 and
with a test lamp, an ohmmeter, or a growler (if it is
7-42) is plugged into a 120-volt, 60-hertz power supply
equipped with test probes and a meter). You then check
and switched to the ON position. A hacksaw blade is
the dc armature for grounds by placing one probe on the held parallel to the windings and run across the top of
armature shaft and the other probe on successive bars of the armature. The armature is continually rotated in the
the commutator until all commutator segments are growler, and the hacksaw blade test made until the
checked. complete armature has been checked. If a short exists
in the winding below the hacksaw blade, the blade will
Armature opens may be determined with test
equipment having test probes to make commutator
bar-to-bar contact around the armature (fig. 7-40), Test
equipment may be an incandescent lamp with a
low-voltage source, a low-reading ohmmeter, a

Figure 7-40.—Testing armature coils for an open circuit. Figure 7-42.—External growler construction.

7-29
vibrate noticeably and will cause a chattering noise. HAND TOOLS
Larger armatures, which do not fit in an external
The hand tools used in rewinding armatures are
growler, may be checked by moving an internal growler
relatively few and simple. In fact, they are usually
over the outside surface of the armature. Internal
handmade by Electrician’s Mates engaged in this work.
growlers are used primarily to check stator windings,
Figure 7-44 shows the following tools:
which will be covered later in this chapter under
three-phase stator repair. 1. A fiber from, which is used for shaping the coil
You should use a dial indicator for armature com- ends after the coils are placed in the slots
mutator radius checks (fig. 7-43). Ensure commutators 2. A steel slot drift, or tamping tool, which is used
are not out-of-round more than 1 mil (0.001 inch). for driving the coils to the bottom of partly
closed slots
REWINDING PROCEDURES 3. A lead lifter, which is used for lifting the coil
leads from the commutator risers
When tests or observations show that a piece of
rotating electrical machinery needs replacing and no 4. A hacksaw blade, which is used for removing
replacement is available, rewinding is necessary. The the fiber wedges that hold the coils in the slots
process for rewinding a piece of rotating electrical gear
5. A handsaw, which is used for undercutting the
is basically the same for all types of machines. The
process can be divided into 9 key steps: commutator mica between the segments
6. A wedge driver, which is used for driving the
1. Disassembly
fiber wedges out of the slots
2. Burning/stripping
7. A lead drift, which is used for cutting off the
3. Recording data leads at the risers
4. Cleaning 8. A rotation indicator, which is used as an aid to
5. Insulating determine the proper connections of the
windings
6. Winding
9. A wire scraper, which is used for removing the
7. Electrical testing
insulation from the ends of the coil leads
8. Varnishing
10. A wedge inserter, which is used for driving the
9. Assembly wedges into partly closed slots

Figure 7-43.—Measuring commutator out-of-round with a

dial indicator. Figure 7-44.—Armature rewinding hand tools.

7-30
INSULATING MATERIALS 3. Where the service life of existing equipment is
shortened by overload, heat moisture, or a
Electrical insulating materials are classified combination of these factors
according to their temperature indices. The temperature
Silicone insulation is not a “cure all” for motor and
index of a material is related to the maximum
generator failures. Before deciding to use silicone
temperature at which the material will provide a
insulation, check the installation to determine the
specified life as determined by tests or by experience.
cause of failure. Misalignment of bearings, mounting
Current-carrying conductors require insulation to bolts dislocated, a bent shaft, failure or
isolate them from electrically conductive parts of the inoperativeness of overload devices, or similar causes
unit and to separate points of unequal potential. An may have initiated the failure rather than the
understanding of the different types of insulation used insulation itself.
will help you in the repair of electrical equipment. The
Consideration must be given to the conditions to
different classes of insulation materials are listed in table
which the windings will be subjected during winding,
7-6.
varnishing, drying, or baking. Class A, B, and F
There are certain conditions when the rewinding of materials are generally tough and will take a lot of abuse.
class A and class B insulated motors with class H Class H and N materials are considered somewhat
insulation becomes necessary. This is done to prevent fragile and should be handled with care in order not to
a recurrence of insulation breakdown and ultimate damage the resin film.
failure. Examples of such conditions areas follows:
Varnish
1. Where the location’s ambient temperature
exceeds the equipment design ambient (usually
The process of varnishing new or reconditioned
50°C or 122°F)
windings helps to prolong the life of the machine by
2. Where excessive moisture (usually condensate) preventing the introduction of water vapor and dirt or
is present and the windings are exposed dust once the machine is placed into operation. In

Table 7-6.—Classes of Insulation

7-31
addition, varnishing helps windings keep their form and 2. Coil side separators, which are placed on top of
adds mechanical strength. The procedures for coil sides as they are laid into slots to prevent
varnishing new windings are given in table 7-7. two coil sides from touching one another within
the same slot. May be made of flat silicon glass
Polyamide Paper
insulation or formed (curved) polyamide paper.
Before placing windings in a stripped stator or
3. Slot wedges, which are used to close up slots
armature the slots must be insulated to prevent current once all coil sides are inserted. They may be
leakage to ground and to insulate the separate windings made of flat silicon glass insulation or formed
from one another. Polyamide paper is available in (curved) polyamide paper.
various thicknesses and dielectric strengths for this
4. Phase insulation, which is used to prevent the
purpose.
ends of adjacent coils from touching one
There are four types of paper insulation used in another. It is made of .007 inch polyamide
winding. paper.

1. Slot insulation, which is used to separate the coil ELECTRICAL TESTS

sides in the slot from the laminations. Prepared Electrical tests are performed on new windings to
from two 7 mil (0.007”) pieces of polyamide. ensure connections are proper and that workmanship is

Table 7-7.—Varnishing Procedures

7-32
satisfactory to prevent improper operation of the
equipment. Tests should be performed before and after
varnishing in order to ensure reliability of the equipment
and prevent the need for rework as much as possible.
Insulation Test for Grounds
Once coils have been replaced or reconditioned, the
equipment insulation must be tested for proper values.
Insulation tests are made as described earlier with a
megohmmeter (fig. 7-45). Values must be as specified
in table 7-5 to ensure safe operation of the equipment.

High-Potential Test
A high-potential testis made by applying (between
insulated parts) a test potential that is higher than the
rated operating voltage. High potential tests are
frequently used in connection with the repair or
reconditioning of naval equipment ashore.

The purpose of the test (fig. 7-46) is to break down

the insulation if it is weak, thereby indicating defective
material and workmanship, and permitting replacement
Figure 7-45.—Type 1863 Megohmmeter.
before actual use. Since this is designed to break down

Figure 7-46.—AC Dielectric test set.

7-33
the insulation, it is considered a destructive test and or more turns of bare wire around the commutator.
should be performed only when necessary. Then, apply the high-potential test voltage across the
common connection of all the commutator segments
The application of each high-potential test tends to
and the grounded armature shaft.
weaken insulation even though it does not produce
actual failure at the time. Also, the use of high-potential A high-potential test should not be made on any
tests requires special equipment and safety precautions. equipment until the insulation resistance has been
measured and found to be satisfactory as per NSTM,
When making high-potential tests on electrical
chapter 300.
equipment that has been reconditioned or rewound in a
shop, you should NOT come in contact with any part of
Surge Comparison Test
the circuit or apparatus. Never touch the winding after
a high-potential test has been made until it has been
The surge comparison tester (figs. 7-47 and 7-48)
connectd to ground to remove any static charge it may
uses the principle of impedance balance to
have retained.
simultaneously test turn-to-turn, coil-to-coil,
Connect all leads to the circuit being tested to one phase-to-phase, and coil-to-ground insulation; in
terminal of the source of test voltage. All the leads to addition, qualitative evaluations are made of a winding’s
all the other circuits and all metal parts should be likelihood of satisfactorily passing resistance,
connected to ground to shunt the voltage produced by impedance, turn balance, and high-potential tests.
transformer action. No leads are to be left unconnected
for a high-potential test as this may cause an extremely Resistance Balance Test
severe strain at some point of the winding. For example,
to make a high-potential test on a rewound armature, Using a Wheatstone bridge (fig. 7-9) or a digital
short-circuit the commutator segments by wrapping one voltmeter (fig. 7-50), the resistances of the windings are
measured very accurate] y to determine whether the
phases are electrically balanced.
The lowest resistance readings are subtracted from
the highest resistance readings. This number is
compared to 5% of the highest resistance reading. If the
difference is lower than 5% of the highest resistance
reading the windings are said to be electrically balanced.

ARMATURE REWINDING

Once an armature has tested bad and been

disassembled, the process of rewinding it can begin.

Figure 7-47.—Baker 5000 Surge Comparison Tester. Figure 7-48.—Representative surge test waveforms.

7-34
 Figure 7-50.—Digital ohmmeter.

The process of armature rewinding involves stripping

the armature, recording the winding data, insulating the
core, placing machine-wound coils in the slots or
rewinding the coils into the slots by hand, connecting
the commutator, testing the windings, varnishing,
baking, and balancing.
Stripping
Before stripping an armature, record all available
Figure 7-49.—Typical Wheatstone bridge.
winding data on an armature data card, as shown in
figure 7-51, for use in rewinding and for future
reference.

Figure 7-51.—A dc generator or motor data card.

7-35
 After recording the initial winding data, perform a compressed air. Dip the cleaned armature core in a
bar-to-bar test to determine if the winding is lap or wave; varnish and bake according to the steps in table 7-7,
then record this information on the armature data card. using a diluted varnish (20 percent varnish, 80 percent
Now you are ready to disconnect and remove the coils. thinner) of the same type to be used after winding.

During this process, record the winding data that This treatment prevents the formation of oxides and
was impossible to obtain before stripping the armature. forms a base for the adherence of the final varnish
Remove the banding wires by cutting them in two treatment.
places. If banding wires are not used, remove the
wedges in the slots. A simple means of removing the
wedges is to place a hacksaw blade, with the teeth down, Winding Armature Coils
on the wedge. Tap the top of the blade to set the teeth
in the wedge, and then drive out the wedge by tapping Formed coils are wound on a coil-winding machine
the end of the blade. and pulled into the desired shape on the forming
Next, unsolder the coil leads from the commutator machine. The shape of the coil is determined by the old
coil. The two wires forming the leads are taped with
and raise the top sides of the coils the distance of a coil
throw (distance between the two halves of a coil). The cotton or reinforced mica tape. The binder insulation,
bottom side of a coil is now accessible, and the other consisting of cotton or glass tape, is applied to the entire
coils can be removed. Exercise care to preserve at least coil surface.
one of the coils in its original shape to use as a guide in
The coil is now sprayed with a clear, air-drying
forming the new coils. Next, record the wire size, the varnish (grade CA), which conforms to Military
number of turns in a coil, and the type of insulation on Specification MIL-V-1137. After the varnish has dried,
the coils and in the slots. the coil ends are tinned to ensure a good connection to
The raise the coils without damaging the insulation, the commutator.
use a small block of wood as a fulcrum resting on the
Preformed windings should be used on large
armature core and a steel bar or piece of wood as a lever.
armatures, but it is more practical to wind small
After the coil is partly raised, drive a tapered, fiber armatures by hand. End room is very limited, and
wedge between the top and bottom coils within the slot windings must be drawn up tightly to the armature core.
to finish raising the top coil from the slot. After stripping Figure 7-52 shows the methods of winding an armature
the armature, remove all dirt, grease, rust, and scale by by hand. One armature in the figure is small enough to
sandblasting. File each slot to remove any burrs or be hand held. The other, too heavy for this, rests on a
slivers, and clean the core thoroughly with dry, support.

Figure 7-52.—Winding armatures by hand.

7-36
Placing Coils in Slots To prevent centrifugal force from throwing the coils
outward, wind a band of high-grade, steel piano wire on
Before assembling the coils, insulate the armature a strip of Lest.kroid placed around the armature and
core. This step is extremely important if the armature over the coils about 2 inches from the edge of the core.
contacts the coils, you will have to do your work over. Do this before the armature has been dipped and after
Clean the core slots and ends and true up the prebaking. Banding wires should be placed on the
laminations. Use polyamide paper, and let it extend armature windings while hot because then the wire is
one-fourth inch beyond the slots to prevent the edges of more flexible and can be pulled tighter. When the first
the laminations from injuring the coils. banding wire is wound on the armature, small tin clips,
with insulation under them, are inserted under the wire.
The ground insulation consisting of flexible mica When the required number of turns has been applied,
wrappers or layers of reinforced mica tape, is applied to the ends of these clips are bent over and hold the wires
the coil sides that lie in the slots. Next, the formed coils tightly side by side. The clips are then soldered with tin
are placed in the slots; the lower side first and then the solder, and a thin coat of solder is run over the entire
upper side, until all the coils are inserted and the winding band to secure the wires together.
is completed. Be certain that the coil pitch is correct. A
The end windings are secured, if necessary, by
strip of rigid laminate, type GME-MIL-P-15037, is
groups of wire wound on insulating hoods to protect the
placed in each slot between the lower and upper coil
coils. On the commutator end, strips of thin mica with
sides. A similar strip is placed at the back and front of
overlapping ends are usually placed on the commutator
the armature where top and bottom sides cross each
neck and held by a few turns of cord. On large
other. If the slots have straight sides, they are filled up
with a strip of rigid laminate, type GME-MIL-P-15037, armatures, banding wires are sometimes placed over the
laminated portion of the armature. The laminations on
on the tops of the coils so they can be held down by the
these armatures have notches in which the banding wire
banding wires. In some armatures the slots are shaped
is placed
so that fiber wedges can be driven in each slot from one
end to hold the coils in place. If you have to rebuild a large commutator, use
molded mica to insulate between the spider and the
Before soldering the coil ends to the commutator
commutator. Commutator mica is used as insulation
segments, test the winding for grounds, opens, and
between the segments. After the commutator is
shorts. When soldering, exercise care to prevent the
assembled, it is heated and tightened with a clamping
solder from falling or running down the back of the
ring.
commutator. This could result in a short circuit. Tip the
armature so that the solder will not flow to the back of If shrink rings are provided, they are not put on until
the commutator. Place the tip of the soldering iron on the commutator has been tightened (while hot) and the
the commutator near the riser and wait until the iron banding wires tightly placed around it. If defective,
heats the riser sufficiently to melt the solder. Touch the small commutators are usually completely replaced.
solder to the riser and allow it to flow around the lead
and into the wire slot, and then remove the iron. REWINDING FIELD COILS

An ordinary soldering iron cannot supply sufficient Remove the old field coil from the pole piece and,
heat fast enough to perform a satisfactory soldering job if spare coils are available, install a new one. If a new
on a large armature. Therefore, apply a soft flame from coil must be made, record all pertinent coil data as the
an acetylene torch to the outside end of the commutator old coil is stripped.
segments to the riser ends where connections are made.
Tin the coil ends that will be connected to the This data should include the following information:
commutator risers with a soldering iron. Next, tin the 1. The dimensions of the coil, both with the tape
slots in the commutator risers with heat from the torch. on and with the tape removed
Then make the connections while applying the flame to
2. The weight of the coil without the tape
the outside end of the commutator segments. When
making the commutator connections, wrap the winding 3. The size of wire
with the proper tape for protection. Too much heat can
4. The type of insulation
damage the winding insulation. The completed
armature winding is checked electrically for continuity The two general classes of coils are shunt field coils
and for shorted turns. and series and commutation field coils. Shunt field coils

7-37
consist of many turns of tine wire and series and of round wire. These coils have only a few turns that
commutating field coils consist of fewer turns of heavy are wound in a single turn per layer.
wire.
A series coil wound (with ribbon copper) on edge is
illustrated in figure 7-54. It is more difficult to bend the
Shunt Coils copper ribbon, but it has an advantage in that both
terminal leads protrude on opposite sides of the coil.
The equipment for rewinding shunt coils include a Thus, the connections can be made very easily
lathe with a suitable faceplate, which can be turned at compared to the strap-wound coils, which have one coil
any desired speed, and an adequate supply of the proper end at the center and the other coil end at the outside of
size wire wound on a spool, which can be supported on the. coil. The strap-wound construction requires leading
a shaft so that it is free to turn. Friction should be applied the inside coil end over the turns of strap in the coil.
to the spool to provide tension on the wire. Secure a coil
form having the exact inside dimensions of the coil to After the winding is completed, the coil is tested
the lathe or faceplate. The form for shaped field coils electrically for continuity and shorted turns. It is then
can be made from a block of wood shaped exactly to the prebaked, varnished, and tested for polarity, grounds,
required size and provided with flanged ends to hold the opens, and shorts, as described previously, at each stage
wire in place (fig. 7-53). One of the flanges should be in turn.
removable so that the finished coil can be taken from the
forming block.
Testing Field Coils
The wire is wound from the spool onto the forming
block for the required number of turns. The turns must
be evenly spaced, one against the other, until the Before installing a new or repaired coil, test it for
winding procedure is completed. The turns of the shorts, opens, and grounds, and determine its polarity.
completed coil are secured by tape, and the wire leading The same precautions that were observed during
to the spool is cut, leaving sufficient length to make the removal of the coil must be observed when installing it.
external connections. The completed coil must be All of the shims originally removed from the pole piece
checked electrically for continuity and for shorted turns. must be in position when it is replaced. With the coil
positioned in the machine, it should be temporarily
The coil is now prebaked and varnish treated as
connected to the other coils in the field circuit and a
specified in table 7-7. When varnish-treated, the
compass and battery again used to check its polarity.
finished field coil should withstand a high-potential test
For this test, connect the battery to the proper field leads,
of twice the rated excitation voltage plus 1,000 volts.
and check the polarity of all the coils with the compass
(fig. 7-55). Adjacent poles must be of oppsite polarity.
Series and Commutating Coils If necessary, the polarity of the new coil can be reversed
by reversing the leads. When the polarity is correct, the
Series and commutating field coils are frequently coil is connected, and the pole-piece bolts are tightened.
wound with strap (rectangular) or ribbon copper instead Air gaps should be measured to ensure uniformity.

Figure 7-53.—Coil form for field coils. Figure 7-54.—Edge wound series coil.

7-38
 Figure 7-57.—Testing a three-phase stator for
shorts.

opens by deliberately shorting each coil. A buzz at

Figure 7-55.—Testing the polarity of field coils.
any of the coils indicates a closed circuit.

If you use a meter-indicating internal growler

THREE-PHASE STATOR TESTING (fig. 7-56), a pointer deflection indicates a short; no
AND REPAIR deflection of the pointer indicates an open circuit.

In testing stator coils as in testing dc armatures, THREE-PHASE STATOR

you will find the most common troubles to be REWINDING
grounds, opens, and shorts.
When tests or observation determine that a
The internal growler (fig. 7-56) is used to check
three-phase stator needs rewinding, retain data must
for shorts and opens on the inside of stators and
be recorded.
stationary fields, or on large armature surfaces where
an external growler cannot be used To make such
It is important to keep an accurate record of all
checks, connect the internal growler to the rated ac
the pertinent data concerning the winding on the
source. Run the internal growler over the coils of a
stator data sheet, as shown in figure 7-58. This
motor or generator and listen over for a buzz (fig. 7-
information should be obtained before stripping; if
57). When a shorted coil exists, transformer action
not, it can be obtained during the stripping operation
causes the growling noise. Coils may be tested for
in the same manner as for dc armatures.

MAKE

HP RPM VOLTS AMP

HERTZ TYPE FRAME STYLE

TEMP. MODEL SERIAL PHASE

NO. OF NO. OF CONNECTION

COILS SLOTS

SIZE WIRE NO. OF NO. OF

TURNS GROUPS

COILS- NO.OF PITCH

GROUP POLES OF COIL

Figure 7-56.—Internal growler. Figure 7-58.—Stator data sheet.

7-39
 You rewind new coils for ac stator windings in the coil and the inside lead of the next coil together.
same manner as for dc armatures, and you have to form Connect the outside lead of the last coil with the inside
and shape them before you place them in the stator slots lead of the next coil and bend the outside lead of this
(7-59).
coil away from the center. Repeat this procedure for
You now insert all the coils in the stator slots, each of the pole-phase groups all around the stator. Do
insulate the ends, and drive the slot wedges in place (fig. not solder the connection at this time.
7-59). Extending from each coil will be the start and
finish leads; these leads must be connected to form a After twisting the ends together, check the
series of coils called a pole-phase group. individual groups to determine that the proper number

In arranging these coils into pole-phase groups, start of coils have been connected together in each
by bending (forming) the inside lead of the first coil pole-phase group and that they have the proper
toward the center, and then twist the outside lead of that polarity. Then solder the twisted connections and cut
off the ends so that the soldered stubs are about
three-quarters of an inch long. Insulate the stubs with
acrylic glass.

If the distance to the bearing brackets (frame of the

machine) is small, bend the insulated stubs so that they
may be laced to the end of the coils before the stator is
dipped. Now the stubs will not come in contact with the
frame when the stator is assembled.

In practice, the coils that comprise the pole-phase

groups are usually gang wound. Gang-wound coils
eliminate the need for stubbing because the coils are
wound with a continuous length of wire.

Series-Wye Winding

Before connecting the pole-phase groups together,

construct a diagram containing the pole-phase groups in
each phase and the number of poles for the particular
machine, as illustrated in figure 7-60. Pole-phase
groups for each phase are connected to produce alternate
north and south poles, and the direction of current flow
through each pole-phase group is indicated by the
arrows.

The As, Bs, and Cs phase leads (s stands for start)

are all connected to one polarity of a small battery; the
Af, Bf, and Cf phase leads (f stands for finish) are all
connected to the other polarity of the battery. If
connections are correct, a compass will give opposite
polarity as it is moved from one coil group to another.
Figure 7-59.—Placing coil sides in slots. Note the changing polarity in figure 7-60.

7-40
 Figure 7-60.—Three-phase, four-pole, series-wye winding.

All the arrows on the line leads (fig. 7-60) indicate

current in the same direction toward the center of the
wye. Actually, the current at one instant may enter the
phase A lead and leave by the other two leads. At the
next instant, current may enter through phases A and B
and leave by phase C (fig. 7-61). At any instant, current
is flowing into and leaving the wye by at least one lead.
This illustrates how a four-pole motor or generator
actually functions. In rewinding, however, having the
current going in at all phases and ending at the internal
star connection (figs. 7-60 and 7-61) is best for bench
testing the stator.

The series-wye connection (figs. 7-60 and 7-61) is

employed in ac machines designed to operate at a
comparative y high voltage. Machines that require a Figure 7-61.—Three-phase, four-pole, series-wye winding
relatively high current usually are wound in a multiple showing the four poles.
or parallel arrangement.

7-41
Parallel-Wye winding groups 1 and 4 are placed in parallel with pole-phase
groups 10 and 7, resulting in an increase in the
To connect the machine for three-phase, four-pole, current-carrying capacity. The voltage drop across that
parallel-wye operation, use the diagram shown in figure phase remains the same without changing the number
7-62 with the same number of pole-phase groups and of pole-phase groups.
the same assumed directions of current flow through the
groups as in the series-wye connection the pole-phase
Series-Delta Winding
groups of the three phases must be connected so that the
current flows through the various groups in the
directions indicated to obtain alternate north and south The same machine connected for three-phase,
poles. Again, connect the battery, as previously four-pole, series-delta operation is illustrated in figure
described, by connecting A, B, and C start phase to one 7-63. The same pole-phase group numbers are allotted
side of the battery; and A, B, and C finish phases to the to the same phase windings, and the directions of current
other side. Again the 12 compass polarities should be flow through the groups are the same as for the other
indicated in one revolution of the stator.
examples.
The only difference between the parallel-wye
Note the difference in the series-wye winding (fig.
winding (fig. 7-62) and the series-wye winding (fig.
7-60) and the series-delta winding (fig. 7-63). In the
7-60) is the four pole-phase groups, which were
originally in series in any one of the phases, but are now series-delta winding, the three phases are connected so
split into two parallel paths of two pole-phase groups. that they form a delta, and the external connections are
In phase A the same coil groups are used, but pole-phase made at the three corners of the delta.

Figure 7-62.—Three-phase, four-pole, parallel-wye winding.

7-42
 Figure 7-63.—Three-phase, four-pole, series-delta winding.

Parallel-Delta Winding 5. No unusual noise or vibration

The machine used in the other examples, connected Testing Direction of Rotation
for three-phase, four-pole, parallel-delta operation is
shown in figure 7-64. The phase windings contain the Once the unit has been installed and aligned, it
same pole-phase group numbers, and the polarities of should be tested for proper direction of rotation. This
the pole-phase groups are the same as in the previous should be done prior to coupling the motor to the driven
cases. load if possible. Running some types of equipment in
the wrong direction may cause a hazard to personnel or
damage the equipment.
POST WINDING TESTS
Once any danger tags have been properly removed
Once repairs have been completed and the unit has the equipment is ready to be “bumped” or momentarily
been assembled, it is necessary to conduct tests to ensure energized to test for rotation. Ships force should be on
that all work has been satisfactorily completed. These hand to verify the rotation of the equipment is proper.
tests include the following:
If the direction of rotation is proper, the unit maybe
1. Roper direction of rotation coupled and further tests conducted. If the direction of
rotation is incorrect, the direction should be reversed by
2. Proper speed one of the following methods.
3. Normal bearing and stator temperature rise REVERSING DIRECTION OF ROTATION OF
4. Balanced phase currents DC MOTORS.— The two methods for reversing a dc

7-43
 Figure 7-64.—Three-phase, four-pole, parallel-delta winding.

motor are (1) changing the direction of current flow

through the armature leads and (2) changing the
direction of current flow through the motor fields. In
compound motors the reversing of rotation is easier
using the first method since a single element is involved.
If the second method is used, it becomes necessary to
reverse the current through both the series field and
shunt field windings.
REVERSING DIRECTION OF ROTATION OF
A THREE-PHASE MOTOR.— To reverse the
direction of rotation of a three-phase motor, all that
needs to be done is to reverse the connections of any two
of the three leads of the motor. That is, reverse either
the A and B, A and C, or B and C phase leads.

Checking Motor and Generator Speeds

Tachometers indicate, in revolutions per minute

(rpm), the turning speed of motors, generators, and other
rotating machines. With the unit operating under
normal conditions, use a portable tachometer (fig. 7-65), Figure 7-65—A chronometric tachometer.

7-44
or stroboscope (fig. 7-66), to measure the speed of a
motor or generator after rewinding.

Temperature Testing

Before operational testing the unit, thermometers

should be placed at each bearing location and at the
mid-point of the stator as a minimum. The ambient
temperature should be recorded for each thermometer.
Once the unit is placed in operation the temperature of
each location should be frequently noted and recorded.
Any unusual/rapid temperature rise must be
investigated and corrected before the test can be
completed.

NOTE: Check bearing temperatures frequently

during operation. Temperatures should not exceed
180°F.

Testing Phase Current Balance

During operation, the phase current of the unit

should be checked to ensure they are within normal
operating limits. When testing dc machines, you need
to have an ammeter installed prior to testing the values
of the phase currents. When testing ac machines, a
clamp-on ammeter (fig. 7-67) can be used.

Figure 7-67.—Clamp-on ammeter.

The current in any phase, at rated load, should not

differ from the arithmetic average of the maximum and
minimum current values by more than that shown in
table 7-8.

Table 7-8.—Maximum Allowable Difference in Phase Currents

Figure 7-66.—Type 1531-AB strobotac.

7-45
 Noise/Vibration Analysis

Once the equipment has been running long enough

to come up to normal operating temperature, it should
be tested to ensure there are no unusual noises and
vibration is not excessive.

Instructions governing procedures to be followed

when conducting noise and vibration analysis can be
found in NAVSEA 0900-LP-060-2020.

This test procedure can be used to identify

immediate or impending bearing problems and
Figure 7-68.—Two major parts of a centrifugal switch. improper balance of rotating elements.

Figure 7-69.—Single-phase motor data card. (A) Front side; (B) back side.

7-46
 Figure 7-70.—Single-phase, capacitor-start, inductor-run motor diagram.

SINGLE-PHASE (SPLIT-PHASE) AC 1. Inspect the motor for defects such as cracked end
MOTOR REPAIR plates, a bent shaft, a broken or burned winding.

There are many applications for single-phase 2. Check the motor forbearing troubles.
motors in the Navy. They are used in interior 3. Test the motor for grounds, opens, and shorts
communications equipment, refrigerators, fans, (see armature and three-phase stator sections).
drinking fountains, portable blowers, portable tools, and
If rewinding is required, record the necessary data
many other applications. Single-phase motors are
on a single-phase motor data card (fig. 7-69).
considerably cheaper in fractional horsepower sizes; but
above 1 horsepower, the three-phase motors are less A single-phase motor connection is shown in figure
expensive. The use of single-phase motors also 7-70. When you connect the motor to a power source
eliminates the need of running three-wire service to of 110 volts ac the motor run windings are connected
in parallel by placing the two connecting bars as shown
supply small loads.
in figure 7-71, view A.
Single-phase motor failure is usually caused by the
starting winding burning out. The centrifugal switch
(fig. 7-68) cuts the starting winding out of the system
when the motor reaches about 75 percent of rated speed.
When the motor is overloaded, the speed decreases and
allows the centrifugal switch to energize the starting
windings. Then, the motor speeds up enough so that the
centrifugal switch opens the starting winding again.
This constant opening and closing of the starting
winding circuit can cause failure of the winding due to
excessive temperature.

Steps in analyzing motor troubles should proceed,

as previously mentioned, following a logical sequence
to determine what repairs are required for Figure 7-71.—Connecting bars. (A) Low voltage input; (B)
reconditioning the motor: High voltage input.

7-47
 When you reconnect the motor to a power source of coil. When coils are placed in stator slots, they can be
220 volts ac, the run windings must be connected in wound in place by hand or wound in a coil winder on
series by placing the two connecting bars as shown in forms, and then placed in the slots of the stator.
figure 7-71, view B.
Capacitors used with single-phase motors for
By tracing through the two series and parallel starting should be checked by means of a capacity tester.
bar-connected circuits, you will note that the starting This also applies to the capacitor-start, capacitor-run
winding operates on 110 volts regardless of a parallel type of motors.
or series connection.
MOTOR AND GENERATOR AIR
Figure 7-72 is a diagram of a four-pole, split-phase
COOLERS
motor. The type of winding used on both the running
and starting windings is the spiral winding. The Some large electric motors and generators, such as
difference between the two windings is their impedance propulsion generators and motors, are equipped with
and position in the stator slots. The running winding has surface-type air coolers. In this system the air is
a low resistance and a high reactance (because of many circulated by fans on the rotor in a continuous path
turns of large wire), and the starting winding has a high through the machine windings and over the
resistance and a small reactance (being wound of small water-cooled tubes of the cooler. The ceder is of
or high-resistance wire). double-tube construction (one tube inside another).
This minimizes the possibility of damage due to water
The running winding is placed in the bottom of the leakage. I&location of the air cooler on a generator is
slots, and the starting winding is placed on top of the shown in figure 7-73.
running winding. Both windings are energized in
parallel at starting. The currents are out of phase with The air and water sides of air cooler tubes must be
each other, and the combined effects produce a rotating kept as clean as possible because foreign deposits will
field that starts the motor (some motors use capacitors decrease heat transfer. When you are required to clean
for starting). When the motor has almost reached the air side of the tubes, the individual tube bundles may
normal speed, the centrifugal switch opens the starting be removed and washed with hot water or cleaned with
winding circuit, and the motor operates as a single-phase a steam jet. The water side of cooler tubes must be
induction motor. cleaned following instructions contained in the NSTM,
chapter 254.
A pole for the running or the starting winding in a
When a leak between an inner tube and the tube
single-phase motor is made up of more than one coil.
These coils differ from each other in size and, depending sheet occurs, water will seep from the cooler head
through the leaky joint into a leak-off compartment and
on the winding specifications, in the number of turns per
out the leakage drain. If a leak in an inner tube, water
will seep into slots in the outer tube where it is carried
to a leak-off compartment and out the leakage drain.
The leakage drain line is equipped to give a visual
indication of the presence of water in the line.

Figure 7-72.—A four-pole, split-phase motor. Figure 7-73.—Generator equipped with an ailr cooler.

7-48
 When a leaky tube is found, both ends of the tube • Provide adequate protection for the part to
should be plugged with plugs provided as spare parts or prevent additional damage. Use the same
with condenser plugs. When the number of plugged container in which the new one was packaged, if
tubes in a cooler section becomes large enough to at all possible.
adversely affect the heat-dissipating capacity of the
• Return the defective part to supply as soon as
cooler, the cooler section must be removed and replaced.
possible.
Since you will encounter the terms mandatory
DO NOT CANNIBALIZE THE PART FOR
turn-ins arid repairables in the process of obtaining
replacement parts from supply, you should understand COMPONENTS YOU THINK YOU MAY NEED
FOR FUTURE USE.
the purpose of the repairable program and your
responsibilities to it. When the required part is not in the storeroom,
When a component fails, your primary concern is supply must take appropriate action to obtain it. The
to locate the trouble, correct it, and get the equipment failed part should be turned into supply before receiving
back on the line. In most cases this involves the new one, unless its removal will cause limited or
troubleshooting the equipment and tracing the trouble reduced operating capabilities.
to the defective component, drawing a replacement
from supply, installing it, and discarding the old one.

The repairable program enters the picture when SUMMARY

defective parts are expensive and can be economically
Now that you have finished this chapter, you should
repaired at a factory. In these cases, the time and money
have a better understanding of motor and generator
saved makes it quicker and cheaper to repair an item
repair and troubleshooting. Some of the areas covered
than to contract with manufacturer to build a new one.
were the proper care and cleaning of bearings, the
The old part should be turned in to supply so that it may
correct seating of brushes on commutator and slip
be repaired and returned to service in the fleet through
rings, and the tests and repairs required for motor and
the supply system.
generator windings.
For the repairable program to work as intended,
you and others have certain responsibilities. At the time The information covered in this chapter does not
you turn in your request for a replacement part, supply include the necessary specifications or the specific
must inform you whether or not it is a mandatory turn-in procedures for repair and maintenance of each piece of
item. At this point proceed as follows: equipment you will encounter. This information can
only be obtained from the Naval Ships’ Technical
• Remove the defective part without damaging it. Manual and the manufacturer’s instruction manuals.

7-49
 CHAPTER 8

VOLTAGE AND FREQUENCY REGULATION

Sophisticated electronics and weapons systems Present ship’s service generators and distribution
aboard modem Navy ships require closely regulated systems are adequate for 60- and 400-Hz type I power.
electrical power for proper operation. The increased Type II power differs principally from type I. Type II
demand for closely regulated power is being met by has more stringent voltage requirements. Better voltage
establishing new standards for ac shipboard power regulation at the ship’s service generator will not satisfy
system. Also, new voltage and frequency-regulating these voltage requirements. This is because the
equipment has been developed. Following a brief specified voltage is at the equipment or load, not at the
discussion of the new standards and equipment, this generator output. Static type line voltage regulators
chapter contains a discussion on the various types of which provide type II voltage control at the load are
voltage regulators for ac generators in use aboard Navy discussed in the chapter.
ships and the SPR 400 in-line regulator.
Voltage and frequency requirements for type III
power cannot be met without isolating the equipment
requiring the power from the rest of the power system.
LEARNING OBJECTIVES Motor generator sets are normally used for this purpose.

Upon completion of this chapter you should be able

to do the following: PRINCIPLES OF AC VOLTAGE
CONTROL
1. Recognize the need for voltage and frequency
regulation. The voltage regulation of an ac generator is the
change of voltage from full load to no load, expressed
2. Recognize the types of power used aboard ship, in percentage of full-load volts, when the speed and dc
and identify their use. field current are held constant.
3. Identify the characteristics of the components
used in various voltage and frequency
regulators.
For example, the no-load voltage of a certain
4. Recognize the operation of various voltage and
frequency regulators in use today. generator is 250 volts, and the full-load voltage is 220
volts. The percent of regulation is
5. Troubleshoot various voltage and frequency
regulators by observing their operation.
6. Recognize the approved servicing techniques
for transistorized circuits. In an ac generator, an alternating voltage is induced
into the armature windings when magnetic fields of
alternating polarity are passed across these windings.
The amount of voltage induced into the ac generator
TYPES I, II, AND III POWER
windings depends mainly on the number of conductors
MIL-STD-761B (Ships) of 15 July 1965 established in series per winding, the speed at which the magnetic
standard electrical characteristics for ac power systems. field passes across the winding (generator rpm), and the
The three basic power supplies (types I, II, and III) are strength of the magnetic field Any of these three factors
described in table 8-1. The power system could be used to control the amount of voltage induced
characteristics shown are those existing at the load. into the ac generator windings.
They do not represent generator output characteristics. This can be represented by the following formula:
All figures are the maximum allowable percentages or
times for that type power.

8-1
Table 8-1.—Standard Elctrical Characteristics for Shipboard Ac Power Systems

8-2
where In almost all applications, ac generators use an
electromagnetic field rather than a permanent magnetic
Eg is the generated voltage output of the generator,
type of field. The strength of the electromagnetic field
K is a constant determined by the physical may be varied by a change in the amount of current
characteristics of the generator (the number of flowing through the coil. This is accomplished by a
windings, their location in respect to the rotating variation in the amount of voltage applied across the
field, the materials used in construction, and so coil. When the excitation voltage to the rotor windings
forth.) is varied, the ac generator field strength is also varied.
Thus, the magnitude of the generated ac voltage depends
represents the strength or intensity of the rotating directly on the value of the exciter output voltage. This
magnetic field, and relationship allows a relatively large ac voltage to be
controlled by a much smaller dc voltage.
N represents the speed or frequency of the rotating
field and thus the frequency of the output. The next principle of voltage regulation that must
be understood is how the dc excitation to the rotor field
The number of windings and their physical
winding is controlled. Voltage control in a dc generator
characteristics are fixed when the generator is
is obtained when the strength of the dc generator shunt
manufactured so K cannot be altered to produce changes field is varied. This is accomplished by the use of a
in voltage. number of different types of voltage regulators.
The various loads throughout the ship require a A device that will vary the excitation current to the
constant value of generated output frequency; therefore, rotor field winding as changes occur in the ac generator
the speed of the rotating field must be held constant. voltage is called an ac generator voltage regulator. This
This prevents the use of the generator speed as a way regulator must also maintain the correct value of exciter
to control voltage output. Therefore, the only shunt field current when no ac voltage corrective action
practical remaining method for obtaining voltage is required (steady state output).
control is to control the strength of the rotating magnetic In figure 8-1, note that a pair of connections labeled
field ac sensing input feeds a voltage proportional to the ac

Figure 8-1.—Simplified voltage regulator circuit.

8-3
generator output voltage to the ac voltage regulator. You When used on dc generators, voltage regulators and
should also note that a portion of the exciter’s armature their auxiliary equipment maintain the generator
terminal voltage within specified limits. They also
output is connected through the exciter’s field rheostat
provide proper division of the load between generators
(Rx) then through the exciter shunt field windings and
operating in parallel.
finally back to the exciter armature. Obviously, the
exciter supplies direct current to its own control field, in When used on ac generators, voltage regulators
addition to the ac generator field, as determined by the and their auxiliary equipment function to maintain
the generator terminal voltage within specified
setting of Rx. The setting of Rx is controlled by the
limits. They also provide proper division of the
magnetic strength of the control coil (L). The magnetic reactive current between generators operating in
strength of L is controlled by the voltage across the parallel.
resistor (R). The voltage across R is rectified dc and is
The types of voltage regulators used in naval vessels
proportional to the ac line voltage. (Rectifiers are
are
devices that change ac to dc.)
Thus, the essential function of the voltage regulator 1. the indirect acting rheostatic,
is to use the ac output voltage, which it is designed to 2. the direct acting rheostatic,
control, as a sensing influence to control the amount of 3. the rotary amplifier, and
current felt by the rotor field windings. A drop in the
4. the combined static excitation and voltage
output ac voltage will change the setting of Rx in one regulation system.
direction and cause a rise in the excitation to the field
One voltage regulator is provided for each generator
windings.
to be regulated. In some ship’s service. installations a
spare voltage-sensitive (control) element is installed on
Conversely, an increase in the output ac voltage
the switchboard. The switchboard is provided with a
will change the setting of Rx in the opposite
transfer switch. This allows the spare element to be
direction and cause a drop in the excitation to the field placed in service if either of the other control elements
windings. These latter two characteristics are caused by become disarranged. Spare control elements are not
actions within the voltage regulator. These installed for voltage regulators used on emergency
characteristics are common to both the resistive and generators.

magnetic (magnetic amplifier) types of ac voltage

regulators. Both types of regulators perform the same INDIRECT-ACTING RHEOSTATIC
functions, but accomplish them through different VOLTAGE REGULATOR
operating principles.

The indirect-acting rheostatic type of voltage

regulators were used on all ac ship’s service
TYPES OF VOLTAGE generators and many emergency generators until
1943. Very few of these voltage regulators are still in
REGULATORS
service; therefore, they aren’t discussed in this
A voltage regulator consists of a control element and TRAMAN.

associated mechanical or electrical means to produce

the changes in the generator field current that are
DIRECT-ACTING RHEOSTAT
necessary to maintain a predetermined constant VOLTAGE REGULATOR
generator terminal voltage. These changes are
necessary to maintain a predetermined constant
Direct-acting rheostatic voltage regulators consist
generator terminal voltage and to provide for proper
of a control element in the form of a regulator coil that
division of the reactive current between generators exerts a mechanical force directly on a special type of
operating in parallel. regulating resistance.

8-4
 The installation of direct-fig (silverstat type) built into the regulator. It is connected in series with the
voltage regulators used on emergency ac generators is shunt field of the exciter. The complete regulator
shown on the schematic diagram in figure 8-2. As you includes
have already learned, in each installation one regulator 1. a control element,
controls one ac generator. When a standby regulator is
2. a damping transformer, and
installed, a standby regulator transfer switch is also
installed. This allows for substituting of the standby 3. across-current compensator
regulator for the normal regulator.
The dc exciter in turn controls the voltage output of
The voltage regulator controls the voltage of the dc the ac generator.
exciter by the variable regulating resistance. This is

Figure 8-2.—Schematic diagram of direct acting voltage regulator installation.

8-5
Control Element a coiled spring are attached to the other end of the
moving arm. The pusher arm carries two insulated
The control element (fig. 8-3) consists of a regulator pusher points arranged to bear against silver buttons.
coil and a regulating resistance. The regulator coil is a These are spring mounted and connected to the
stationary coil wound on a C-shaped iron core with a regulating resistance.
spring-mounted moving arm. The nonmagnetic The silver buttons are individually mounted on leaf
spring-mounted moving arm is pivoted so that an iron springs. They are insulated from each other. They are
armature attached to one end is centrally located in the connected to consecutive taps on the stationary
fixed air gap of the magnetic circuit. A pusher arm and regulating resistance plates (fig. 8-4). The resistance
plates consist of tapped resistance wire embedded in
vitreous enamel. The control element includes two
resistance plates. There is one for each silver button
assembly. They are mounted in the rear of the unit. The
silver buttons connect to taps from the associated
resistance plate.

The control element also includes two adjustable

range-setting resistors (fig. 8-3). They are connected in
series with the regulator coil. These resistors are used
to set the range (covered by the voltage-adjusting
rheostat) so that rated generator voltage is obtained with
the voltage-adjusting rheostat in the midposition.

The primaries of two potential transformers,

connected in open delta, are connected across the
terminals of the ac generator as shown in figure 8-2. The
secondaries of these transformers are connected to a

Figure 8-3.—Control element of a direct-acting voltage

regulator. Figure 8-4.—Silver button assembly.

8-6
three-phase, full-wave rectifier through the Conversely, when the alternating voltage decreases,
compensator. The dc output of the rectifier is applied to the following events occur:
the series circuit. This consists of the regulator coil,
range-setting resistance, voltage-adjusting rheostat, and 1. The regulator operates in the opposite direction.
secondary of the damping transformer. In the following This is because of the pull exerted by the coiled
description of operation, note that the standby regulator spring.
on the left side of the schematic (fig. 8-2) is not 2. This action shorts out resistance in the exciter
energized or used field circuit.
When the regulator coil is energized, the magnetic 3. The impulse from the damping transformer
pull on the iron armature is balanced against the momentarily opposes the decrease in regulator
mechanical pull of the coiled spring. coil current.

IF THEN 4. This action reduces the extent of the decrease in

regulator coil current.
The magnetic pull of Silver buttons are separated
5. This then restricts the magnitude of the increase
the armature over- from each other, adding
in exciter field current and armature voltage.
comes the pull of the more resistance in the field
spring circuit
Damping Transformer
The tension of the Silver buttons are pressed
coiled spring over- together, causing less
The damping transformer is an antihunt device. It
comes the pull of the resistance in the field
armature circuit consists of two windings placed on the center leg of a
C-shaped laminated iron core. The primary of this
transformer is connected across the output of the exciter
Thus, the moving arm operates through its travel,
(fig. 8-2). When a change occurs in the exciter voltage,
depending on the direction of motion, to successively
the primary of the damping transformer induces a
open or close the silver buttons. This increases or
voltage in its secondary. The secondary voltage acts on
decreases the resistance in the exciter field. The moving
the regulator coil to dampen the movement of the
arm has a short travel so that all resistance can be
armature. This prevents hunting and excessive changes
inserted or cut out quickly. It can also be varied
in the generator terminal voltage.
gradually. This depends on the required change in
excitation. The voltage-adjusting rheostat (fig. 8-2) is used to
raise or lower the regulated value of the ac generator
For example, when the alternating voltage rises, the
voltage.
following events occur:

1. The regulator operates because of the increasing The regulator control switch has three
magnetic pull on the armature. positions—MANUAL, TEST, and AUTOMATIC.

2. This action inserts resistance in the exciter field When the control switch is in the MANUAL
circuit to reduce the exciter field current and position, you can control the ac generator voltage
armature voltage, manually by the exciter field rheostat (fig. 8-2).

3. The primary of the damping transformer across When the control switch is in the TEST position (as
the exciter circuit is subjected to this change in shown), the control element is energized. However, the
current. Through transformer action, a regulating resistance is shorted out. The current in the
momentary voltage is induced in the secondary exciter field circuit can be varied by the exciter field
that opposes the increase in regulator coil rheostat. The operation of the moving arm in the control
current. element can be observed.
4. This action is a form of negative feedback. It
When the control switch is in the AUTOMATIC
lowers the magnitude of the increase in regulator
position, the generator is under full control of the
coil current.
regulator. The regulator will adjust the voltage to the
5. This restricts the magnitude of the decrease in value predetermined by the position of the
exciter field current and armature voltage. voltage-adjusting rheostat.

8-7
 When operating the control switch from the pick up the voltage drops from the resistor-reactor
MANUAL to the AUTOMATIC position, you should combination. The output potential terminals of these
pause in the TEST position. This allows the transient transformers (X1, X2 and Y1, Y2) are connected in
current in the regulator coil circuit to disappear without series with the ac potential leads. These leads are
effecting the ac generator output voltage. The transient between the secondaries of the two 440/110-volt open
current is caused by the sudden connection of the delta potential transformers and the three-phase,
damping transformer primary across the exciter full-wave rectifier. This rectifier supplies direct current
armature. for the regulator coil. The compensator is designed to
supply compensating voltages in two legs of the
Cross-Current Compensator three-phase regulator potential circuit. This ensures that
a balanced three-phase voltage is applied to the regulator
When two or more regulator-controlled ac
element.
generators operate in parallel on the same bus, you must
equalize the amount of reactive current carried by each The taps on the autotransformer are connected to
generator. This equalization of reactive current is two DIAL SWITCHES (not shown) on the compensator
accomplished by giving the regulator a drooping faceplate. One of these switches provides a coarse
characteristic. This is done by a cross-current adjustment. The other provides a fine adjustment of the
compensator provided with each ac generator and compensator. A total of 24 steps is available on the two
associated regulator. switches. In the case of the standard 12-percent
The compensator (fig. 8-2) consists of a tapped compensation, this gives a one-half percent change in
autotransformer connected across a resistor-reactor compensation per step. The 12 percent compensation is
combination The autotransformer is energized from a based on four amperes supplied from the current
current transformer. It is connected in the B phase of transformer. If the current transformer ratio should
the ac generator between the generator terminals and give some other value of secondary current,
the bus. Two isolation transformers, with a 1-to-1 ratio, the compensation settings will be affected

Figure 8-5.—A Silverstat voltage regulator on an ac generator.

8-8
proportionally. You should set the compensating droop This action prevents a further decrease in the
introduced by the compensator to approximately 6 terminal voltage. When the voltage decrease is
percent from no load to full load at 0.8 lagging power checked, the moving arm of the regulator is again in a
factor. However, when you have made the proper balanced state. The position of the regulator moving
connections and settings, no further adjustments should arm, however, has changed to correspond to the increase
be necessary. in load on the generator.

If some load is removed from the generator,

Operation

When the generator circuit breaker is closed and the

control switch is in the AUTOMATIC position, the
generator is under control of the voltage regulator (fig.
8-5). If the ac generator voltage is normal, the regulator
moving arm is at rest in a balanced state.

If an additional load is placed on the generator,

The Silverstat voltage regulator can increase the

excitation to the ceiling voltage of the exciter. It can also
reduce the excitation to the lowest value required.
Because total travel of the moving arm is only a fraction
of an inch, the regulating resistance can be easily varied.
This depends upon the requirements of the operating
conditions.

8-9
 To place the voltage regulator in control for the first If operated in parallel with a generator already
time, you should perform the following steps: connected to the bus, close the circuit breaker of the
incoming generator only when the two outputs are
synchronized. The incoming generator can be
connected to the line with the regulator control switch
in the NORMAL or AUTOMATIC position. As soon as
the two generators are operating in parallel, readjust the
governor motor (speed-changer) until each unit takes its
share of the kilowatt load.

To shut down the unit, remove the kilowatt load on

the generator by turning the governor motor control
rheostat while observing the wattmeter. If necessary
turn the voltage adjusting rheostat in a direction to
reduce the reactive load. As the load approaches zero,
open the generator line circuit breaker.

Maintenance

In addition to the actions shown on the maintenance

requirement cards and the instructions given in the
voltage regulator technical manuals, routine
maintenance should include ensuring that connections
are tight and strictly in accordance with installation
diagrams. This maintains the effective resistance in the
shunt field circuit of the exciter. You should also ensure
that the operation of the silver buttons is smooth
throughout the entire travel of the movable core.
It would be advisable to review the information
To place the regulator in control of the ac generator
voltage, you should perform the following steps: about silver contacts in chapter 6, Motor Controllers.
Contacts made of silver or its alloys conduct current
when discolored (blackened during arcing) with silver
oxide. This discolored condition therefore requires no
filing, polishing, or removing.

ROTARY AMPLIFIER VOLTAGE

REGULATOR

The rotary amplifier (amplidyne) type of voltage

regulator uses a special type of exciter. It finishes a
large change in output voltage for a small change in the
control field current of the exciter. The control element
detects variation of the ac generator voltage from a
reference voltage. This can be set to a predetermined
value. The variation between the actual alternating
voltage and the reference voltage sends a current
through the control field of the exciter. This changes its
output voltage current and hence, changes the ac
generator field current. This holds the alternating
voltage at the desired value.

The complete amplidyne voltage regulator

equipment consists of the following components:

8-10
 1. An amplidyne exciter (1) In the GEN A position, the standby regulator has
taken control from the normal regulator of generator A.
2. A pilot alternator (2)
Generator B is connected to its normal regulator.
3. A stabilizer (3)
In the GEN B position, the standby regulator has
4. A voltage-adjusting unit (4) taken control from the normal regulator of generator B.
5. An automatic control unit (5) Generator A is connected to its normal regulator.

6. A manual control unit (6)

Amplidyne Exciter
7. A potential unit (7)
This is illustrated by the block diagram in figure 8-6. The amplidyne exciter (fig. 8-6) is a rotary amplifier
that responds quickly to small changes in control field
Some installations include two normal voltage
current to cause large changes in output. It is mounted
regulators and one standby regulator for two ac
on the shaft of the prime mover. It provides the
generators.
excitation for the ac generator.
A cutout switch with two positions (manual and
automatic) is provided for each generator. The cutout Pilot Alternator
switch is used to connect the amplidyne exciter and the
regulator for either manual or automatic control of the A voltage regulator requires a “reference” or
ac generator voltage. standard to which the voltage being regulated may be
A transfer switch with three positions (NORMAL, compared. This determines whether or not the regulator
GEN A, and GEN B) is also provided. The transfer should act to change the excitation of the ac generator,
In a direct-acting voltage regulator, discussed above, the
switch permits substituting the standby voltage
regulator for either of the two normal regulators. reference is provided by a coiled spring. In the
amplidyne voltage regulator, the reference is provided
In the NORMAL position, generators A and B are by a “boost” current. Ths current is approximately 0.5
connected in the normal automatic voltage control ampere from the pilot alternator. The pilot alternator
circuits of their respective regulators. The standby (fig. 8-6) is a small permanent-magnet, single-phase ac
regulator is disconnected. generator, mounted on an extension of the amplidyne

Figure 8-6.—Block diagram of an amplidyne voltage regulator system.

8-11
shaft. The effective voltage output of the pilot alternator panel. The saturated reactor is the main component of
is essentially constant. the voltage-adjusting unit. It is the heart of the regulator
system.
Stabilizer
The saturated reactor determines the ac generator
voltage that the regulator will maintain. It consists of a
The stabilizer (fig. 8-6) is mounted on or near the
tapped coil of approximately 400 turns wound on a soft
amplidyne exciter. It prevents sustained oscillations in
iron core. The core is operated in the saturated region
generator output. It is essentially a transformer.
so that a very small change in the applied voltage and
However, because it is in a de circuit, the stabilizer
flux density will produce a large change in coil current.
functions only when there is a change in the exciter
voltage. The secondary winding is connected in series Changing the taps on the coil changes the reactance
with the control field of the amplidyne exciter. of the coil circuit. It also changes the voltage level held
When the regulator operates to change the exciter by the regulator. Increasing the turns (to a higher tap
number) increases the reactance and voltage required to
voltage, a voltage is induced in the control field circuit
maintain a given coil current. Conversely, decreasing
through the stabilizer. This momentarily affects the
the turns decreases the reactance and voltage required
control field current to restrain the regulator from
to maintain the current. Tap changing is done only
making excessive correction of the exciter voltage. This
during original installation or an overhaul.
prevents hunting.

Voltage-Adjusting Unit Automatic Control Unit

The voltage-adjusting unit provides ac generator The automatic ccontrol unit (fig. 8-8) has the static
voltage that the regulator will maintain. This unit (fig. elements that are required for automatic voltage control.
8-7) consists of a tap switch and a tapped saturated It is mounted inside the generator control switchboard.
reactor. It mounts directly behind the generator control Portions of the control-unit circuit make the voltage
panel. The handle of the tap switch is on the front of the regulator responsive to the average of the three-phase

Figure 8-7.—Voltage-adjusting unit.

8-12
 Figure 8-8.—Automatic control circuit.

voltages of the generator. Also, a frequency- in such a direction (from F1 to F2) that the amplidyne
compensating network permits the regulator to hold the will boost the ac generator voltage. The saturated
ac generator voltage practically constant between 57 reactor circuit tries to force current through the control
and 63 Hz. field in the opposite direction (from F2 to F1). This
tends to decrease the generator voltage. When the ac
A schematic diagram of the automatic control
generator voltage is near normal, the regulator is at its
circuit is shown in figure 8-8. The circuit consists of a
normal operating point. The boost current supplied by
buck circuit, shown in heavy lines, and a boost circuit,
the pilot alternator is in the opposite direction. It is
shown in light lines. The ac portions of the circuit are nearly equal to the buck current supplied by the
indicated by double-headed arrows. The dc portions are saturated reactor circuit. Thus, the current through the
represented by single-headed arrows. The saturated control field is negligible. The amplidyne excitation is
reactor, Ls, is energized by the ac generator voltage that provided by the series field of the amplidyne to maintain
is to be regulated. It is connected to rectifier CR1. The normal terminal voltage of the ac generator.
pilot alternator feeds rectifier CR2. The amplidyne
If the generator voltage should drop slightly
control field, F1 and F2, is connected across the output
below normal, the buck current supplied by the
of CR1 and CR2. The amplidyne exciter supplies the
saturated reactor would drop, considerably. This action
ac generator field directly.
causes a boost current to flow in the control field, which
The voltage from the pilot alternator tries to force tends to raise the ac generated voltage and prevents a
current through the amplidyne control field. It does this further decrease in the terminal voltage.

8-13
 This action occurs because the pilot alternator is not
affected by the generator voltage and is still trying to
force a boost current through the control field

If the generator voltage increases slightly above

normal, the saturated reactor circuit would pass a large
additional current through the amplidyne control field.
This tends to buck or decrease the ac generated voltage
and prevents further increase in terminal voltage.

Manual Control Unit

The manual control unit (fig. 8-6) controls the

voltage of the generator when the automatic control
equipment is not in use. It consists of two resistor plates
and a single-phase, full-wave rectifier. The two resistor
plates are connected as a rheostat and a potentiometer,
which operate concentrically. The manual control unit
is mounted inside the switchboard. The operating
handwheels protrude through the front of the panel. The
large handwheel provides coarse voltage adjustment.
The small handwheel is used for fine or vernier
adjustment.

Potential Unit

The potential unit (fig. 8-6) provides signal voltage

to the regulator. This voltage is proportional to the
voltage of the ac generator. The unit has a potential
transformer and a potentiometer rheostat. The unit is
mounted inside the generator switchboard near the
current transformer and the generator circuit breaker.
The potential transformer is a special T-connected,
450-volt transformer. The potentiometer rheostat is
connected in the circuit of a current transformer. It is
used to provide the reactive load division between
generators operating in parallel.

Three-Phase Response Circuit

The three-phase response circuit (fig. 8-9) consists

of the following components:
1. AT-connected potential transformer (T)
2. A resistor (R) Figure 8-9.—Three-phase response circuit.

3. An inductor (L)
respectively (fig. 8-9, view B). The relationship of these
The resistance and inductance are in series across voltages is 4-7-5, giving a resultant voltage, 7-0, in
one secondary winding of the potential transformer (fig. phase with and added to the voltage 0-6.
8-9, view A). When a balanced three-phase voltage is
impressed on the primary, 1-2-3, a voltage, 4-5-6, The resulting voltage, 7-0-6 (Vr), is the voltage of
appears across the secondary. The voltages across the the network used to energize the regulator circuits. The
inductor, L, and the resistor, R, are 4-7 and 7-5, regulator at constant frequency will always act to

8-14
maintain voltage Vr constant. If there is any deviation the frequency effect on the saturated reactor. It passes
in generator voltage from its normal value, the system the same buck current at a particular line voltage at any
will make corrections until the three-phase voltages, frequency between 57 and 63 Hz.
1-2-3, are the values that will produce normal voltage
V r. Reactive Compensation

Correct phase sequence of the connections of the When ac generators are operated in parallel,
potential unit to the generator leads is required for division of the load between machines is a function of
correct functioning of this network. If the connections the governors of the prime movers. The division of the
are reversed, for example, by interchanging the two reactive load (kVA) is a function of the regulators, which
leads from the secondary teaser winding, the voltage, increase or decrease the excitation of the generators.
7-0, would be subtracted from the voltage, 0-6, instead
of added to it. The voltage, Vr, impressed on the The division of the reactive load (kVA) between
regulator would then be approximately one-fifth the generators (when operated in parallel) is accomplished
required value. Thus, the regulator in attempting to go by a compensating potentiometer, P, and a current
to the ceiling voltage would overexcite the generator to transformer, CT, provided for each machine (fig. 8-9,
abnormal levels. view A). The rheostat is connected in series with the
teaser leg of the T-connected potential transformer
Frequency Compensation secondary. The current transformer is connected in the
B phase of the generator. Its secondary is connected
The reactance of the saturated reactor (fig. 8-8) across one side of the potentiometer.
increases as the frequency increases. Thus, an increase The generator voltage, 1-2-3, feeds the primary of
in frequency from 60 to 63 Hz at normal 100 percent the T-connected potential transformer (fig. 8-9, view A).
voltage would decrease the buck current. The boost The line current, Ib, of phase B in which the current
current would predominate so the regulator would tend transformer is connected, is in phase with the
to hold a higher voltage. A frequency lower than 60 Hz line-to-neutral voltage at unity power factor. I b is at 90°
would have the opposite effect. This would tend to to the voltage, 2-3 (fig. 8-9, view C). At any other power
increase the buck current so it would predominate. The factor, current Ib swings out of phase with the
regulator would then tend to hold a lower voltage. line-to-neutral voltage depending on lag or lead
Therefore, a voltage regulator system using a conditions.
saturated reactor must have a means to compensate for The secondary voltage, 7-6 (fig. 8-9, view B), which
frequency changes. Frequency compensation is is the resultant output voltage of the three-phase
provided by an inductor, L1, and a capacitor, C 1, in response network, is in phase with the line voltage, 2-3,
parallel with each other. They are across the resistance and is the voltage impressed on the saturated reactor. At
portion of the positive phase sequence network used for unity power factor, current Ib produces a voltage, 6-8,
three-phase response (fig. 8-8). The values of the across the compensating rheostat, P, which is 90°
inductor and capacitor are such that at 60 Hz they out-of-phase with voltage 7-6 (fig. 8-9, view C). The
provide a resonant parallel circuit. This acts like a high voltage 6-8 (IbR p) is the compensating voltage. The
resistance. The other components of the system are voltage 7-8 (Vr) is now impressed on the saturated
adjusted so this resistance has no effect on the action of reactor. The regulator tends to hold the voltage
the regulator at normal frequency. proportional to 7-8.
When the frequency increases above 60 Hz, the When two duplicate generators, A and B, are
parallel circuit has a capacitive effect. This raises the operating in parallel at rated power factor, the
apparent voltage “seen” by the saturated reactor. his line-currents, I, will be equal. The voltage 7-8 (Vr,)
causes it to pass as much buck current on normal voltage “seen” by the saturated reactors of both regulators will
at the higher frequency as at normal frequency. also be equal if the following conditions exist:
When the frequency decreases below 60 Hz, the 1. The field currents are balanced (made equal)
parallel circuit has an inductive effect. This lowers the
2. The compensating rheostats are set at the same
apparent voltage as “seen” by the saturated reactor. This
value of resistance
causes it to pass as much buck current at normal voltages
at the lower frequency than it would at normal 3. The governors are set for equal division of the
frequent y. Thus, the parallel circuit compensates for kilowatt load

8-15
 Assume an instantaneous unbalance occurs with the regulators for generators A and B, respectively, will
generator A having a weaker field than generator B. then be equal to each other.
This unbalance can be caused by slight differences in
The regulator attempts to hold voltage Vr constant.
the reactance or saturation characteristics of the Voltage, 7-8, depends on the value and phase angle of
generators or in the characteristics of the regulators. the compensating voltage, 6-8. The network voltage,
Because the excitation is unbalanced, there is a 7-6, which is the difference between Vr and 6-8 and is
circulating current between the two generators. Their proportional to the line voltage, has decreased slightly
power factors are therefore unbalanced. because of this change. Thus, the line voltage will be
The effect of this unbalance distorts the voltage slightly less than that maintained before any change
triangle, 7-6-8 (fig. 8-9, view C). The network voltage occurred to the system. This drop in line voltage
resulted from the increase in reactive load current.
7-6, decreases slightly because of the drop in line
voltage. The compensating voltage, 6-8 (IbR p), from
the current transformer and the compensating rheostat Manual Control Circuit
have changed. This is because of the unbalanced line
currents and power factors. Therefore, the An elementary diagram of the manual control
compensating voltage, 6-8, for generator B is greater circuit is illustrated in figure 8-10. The buck and boost
and at a different phase angle than the corresponding circuits are indicated by heavy and light arrows,
respectively. The voltage that the amplidyne exciter
voltage for generator A. Thus, the resultant voltage, 7-8
will maintain across its terminals can be adjusted by the
(Vr), of the two machines is unequal and different from
manual control rheostats. Thus, the ac generator
the original voltage that the regulators were set to hold
terminal voltage can be varied. The manual control
constant .
circuit is so designed that for any one setting of the
The regulators will act to change the excitation of manual control rheostat, the amplidyne terminal voltage
the two generators. This is done to restore the voltage, applied to the generator field will remain constant.
7-8, to equal values of Vr for both regulators. They are
set by changing the values of the field currents so they Operation
are balanced. The line currents and power factors will
then be approximately balanced to give equal The schematic diagram of an amplidyne voltage
compensating voltages, 7-8. These voltages “seen” by regulator installation is shown in figure 8-11.

Figure 8-10.—Manual control circuit.

8-16
Figure 8-11.—Schematic diagram of amplidyne voltage regulator installation.

8-17
 The normal operational sequence for placing a Table 8-3 gives the procedure to remove an
single generator on the line is as shown in table 8-2. alternator from the line.

Table 8-2.—Normal Operating Sequence for Starting One Table 8-3.—Removing an Alternator From the Line
Generator

Maintenance

Maintenance instructions for a specific rotary

amplifier regulator given in the MRC and 3-M
instructions take precedence over other procedures.
However, the articles concerning care of rotating
electrical machinery in chapter 310 of the NSTM should
be observed in all cases where they do not conflict with
the MRC, 3-M, or manufacturer’s instructions.

If the generator is to be operated in parallel with a The amplidyne’s short-circuiting brushes should be
generator already connected to the bus, close the circuit checked periodically. Improper brush contact may
breaker of the incoming generator only when the two result in an excessively high amplidyne voltage output.
voltages are synchronized. As soon as the two
generators are operating in parallel, readjust the STATIC EXCITATION AND VOLTAGE
REGULATION SYSTEM
governors of the prime movers until each unit takes its
share of the kW load. Then equalize the power factors
The static excitation voltage regulator system
of the machines by means of the voltage-adjusting units.
furnishes ac generator field current by rectifying a part
When the kW loads and power factors on the generators
of the ac generator output. After the ac generator has
are equal, the current of each generator should then be
built up some output with the aid of a field-flashing
equal. power source, an automatic voltage regulator controls
If the system voltage is high after the power factors the output of a static exciter to supply the necessary field
are balanced, slowly turn the voltage-adjusting units of current.
both generators in the lower direction. Turn it until the The schematic of a static excitation and magnetic
system voltage is approximate y 450 volts. If the system amplifier-type voltage regulator system is illustrated in
voltage is low, slowly turn the voltage-adjusting unit of figure 8-12. The system provides field excitation in
both generators in the raise direction until the system either manual or automatic control for the 400-kW,
voltage is approximately 450 volts. 450-volt, three-phase, 60-Hz generator.

8-18
Figure 8-12.—Elementary diagram of static excitation voltage regulator system.

8-19
 The control switch (S1) in figure 8-12, view B, has Switch S2 is an assembly of 18 contacts (fig. 8-12,
three positions-OFF, MANUAL, and AUTOMATIC. view C). They are connected in series, operate
The setting of this switch determines the type of simultaneously, and function as a single ON-OFF
operation to be used. The OFF position can be device. Again, the function (using many contacts)
used to quickly de-energize the generator in case serves to break a long arc into several smaller arcs and
of an emergency. With the switch in the OFF produce longer life for the heat-dissipating contacts.
position, four sets of contacts (sets P, Q, R, and S)
are closed. Contacts P, Q, and R “short circuit” the
Static Exciter
potential winding of the three potential transformers.
They are identified as T1, T2, and T3 in figure
8-12, view A. They remove rectified current As you read this section about the static exciter,
from the exciter. Concurrently, contact S (upper refer to figure 8-13. The static exciter consists of a
right, fig. 8-12, view A) functions to trip the main three-phase rectifier; CR1, three linear inductors, L1,
breaker. L2, and L3; and three transformers, T1, T2, and T3.

An analysis of the contact arrangement (fig. 8-12, The transformers are alike and interchangeable.
view B) in switch S 1 shows 32 contacts are placed (four Each transformer has four windings (figure 8-13 shows
per pole) on 16 poles. The first four poles produce 8 only the three windings that perform in the basic exciter
single-pole-single-throw contact switches (each SPST circuits). The first winding is the potential or primary
identified by 8 letters, A through H). These 8 have 12 (P2) winding, the second winding is the secondary (S-2)
terminals (identified further by 12 numbers, 1 through winding, and the third winding is the current winding.
12). The fourth winding is the control winding, which is
discussed later. Each transformer is identified as a
The fifth pole (No. 5 in fig. 8-12, view B) has
saturable current potential transformer (SCPT).
only two numbered terminals (13 and 14) to identify
switch section I. Its two SPST contacts are arranged in The primary windings of T1, T2, and T3 are
series. The function of this series arrangement is Y-connected through the linear inductors L1, L2, and L3
twofold: by conductors 13, 14, 15, and 23.

1. It provides two contacts that can open fast The secondary winding is delta connected to diodes
and wide, preventing excessive arcs (A, B, C, D, E, and F) of rectifier CR1 by means of
produced (in an inductive-reactance circuit) conductors 16, 17, and 18. Rectifier CR1 delivers de to
during the OFF “break” of the switching conductors 11 and 9, which supply the generator field.
action.
The current in the control windings CW1, CW2, and
2. It provides optimum cooling of heated contacts
CW3 (fig. 8-12, view A) controls the output of the SCPT
that become hot from arcing.
secondaries and thus the output of the static exciter. The
The remaining 11 poles of switch S1 are arranged control windings are supplied by the voltage regulator
with series assemblies like switch section I. They output as discussed later. Load current flowing in the
are identified by letters J through T, with their current windings (I1, I2, and I3 in fig. 8-12, view A)
terminals numbered 15 through 36. Switch section compensates for changes in the generator load.
T is a spare. The letter X denotes those contacts that
are closed and letter 0 denotes those contacts that FIELD-FLASHING CIRCUIT.— The static
are open when the switch is put into a selected exciter cannot supply field current until some ac voltage
position of OFF, MANUAL, or AUTOMATIC. S 1 is has built up on the 400-kW generator. DC power is
shown in the AUTOMATIC position in figure 8-12, temporarily provided by a 50-kW dc generator
view A. delivering 120 volts.

8-20
 Figure 8-13.—Static exciter.

Perform the following procedure to start the system:

1. Place the control switch (S1) in either the

MANUAL or AUTOMATIC position.
2. Move the spring-return field-flashing switch S-2
(fig. 8-12, view C) to the FLASH position. This
allows flashing current to flow temporarily to
the field of the ac generator, as shown in figure
8-14, when the prime mover is started and the
generator is brought up toward its rated speed.
3. Remove switch S2 as soon as the generator
voltage begins to build up. This is because
thereafter the static exciter is capable of
continuing the dc voltage required by the
generator field.

The field does not have to be flashed every time the

system is placed in operation. It is usually necessary to
flash the field only after a generator malfunction or
when the generator is idle for long periods of time, such
as overhaul periods. Figure 8-14.—Field-flashing circuit.

8-21
 MANUAL VOLTAGE CONTROL CIRCUIT.— which is not now required. Manual control of generator
With switch S1 (fig. 8-15) in the manual position, voltage is achieved by the manual control rheostat R7.
contacts F and H are closed, connecting the 29-volt Varying the resistance of potentiometer R7
secondary of transformer T5 to the bridge rectifier CR2. functions to vary the saturation of the cores of T1, T2,
The resulting dc signal flows in the following manner: and T3. Varying the amount of dc alters the core
1. From the negative terminal of CR2 through saturation. Those variations will change the voltage
resistor R6 value that is induced from each primary into its
associated secondary winding (8- 13).
2. Through the manual control rheostat R7,
3. Through closed switch S1-D to conductor No. Automatic Voltage Regulator
22, and
4. Through the series arrangement of each SCPT The static exciter alone (fig. 8-13) will not maintain
control winding. the different amounts of field current required to
maintain a constant value of ac voltage at the generator
5. There, it combines temporarily with the flow of terminals during various load changes. Therefore, a
the generator’s dc field passing from the+ side voltage regulator is needed to hold the generator voltage
to the – side of rectifier CR1, and finally constant.
6. It terminates at the positive terminal of rectifier
The automatic regulator controls the exciter output
CR2.
by precisely regulating the flow of dc in the control
Five switch sections of S1 are closed to establish winding of each SCPT (T1, T2, and T3 shown in figure
manual control for the exciter’s output, namely, B, D, F, 8-16). Here, the initial ac is provided by the 85-volt
H, and O. Switch S1-0 short circuits the output of secondary of transformer T5. This feeds rectifier CR6
transformer T4 to eliminate a drooping characteristic, (through terminals 41 and 52) to provide the dc source

Figure 8-15.—Manual voltage control circuits.

8-22
 Figure 8-16.—Final-stage magnetic amplifier.

at terminals 39 and 42. The flow of dc is precisely SENSING CIRCUIT.— To obtain the best
controlled by the ohmic reactance values of each coil of regulation during unbalanced load conditions in the
L6. three phases, the regulator uses the sensing circuit (fig.
8-18, view A), which responds to the average of the three
The reactance of each coil of L6 is controlled by the
values of ac line voltages (terminals 4,5, and 6).
state of magnetic saturation produced by the regulated
dc flow from rectifier CR5 of the first stage magnetic Transformer T6 reduces the line voltage of each
phase to a convenient value. Rectifier CR3 converts the
amplifier (fig. 8-17, view A). This regulated dc signal
three-phase ac to dc voltage. If an unbalanced condition
is transmitted to the control windings of the coils in L6
causes the three line voltages to become unequal, the dc
through terminals 5 and 6 of fig. 8-12, view A.
across the rectifier will have considerable (third
The control of this regulated output of rectifier CR5 harmonic) ripple. However, the combined filter actions
originates with sampling the average of the three line of inductor L4 and capacitor C1 will remove the ripple
voltages by the sensing circuit in figure 8-18, view A. and produce dc across C1 (near 50 volts). This is always
in proportion to the average of the three line voltages.
This voltage is processed further in the reference and
comparison circuits (fig. 8-18, views B and C) for Resistor R8 is used for reactive droop compensation
amplification in the preamplifier of figure 8-17. and will be discussed later.

8-23
 Figure 8-17.—First-stage magnetic amplifier.

REFERENCE CIRCUIT.— The reference circuit region and having nearly a constant 6.2 voltage drop
(fig. 8-18, view B) consists of resistor R9 and Zener across each unit.
diode CR4. The function of CR4 is to supply a nearly
COMPARISON CIRCUIT.— The comparison
constant (25 volt) reference voltage to the comparison
circuit consists of the reference circuit (fig. 8-18, view
circuit (fig. 8-18, view C). Dropping resistor R9 limits
B), combined with resistors R10, R11, and R12 (fig.
the current through CR4 to a safe value. If the voltage
8-18, view C). Its function is to compare the “average
(near 50 volts) across R9 and CR4 increases, the current
line voltage” to the reference voltage. It also acts on the
increases in both items. The voltage increases only
first-stage magnetic amplifier to correct any transients.
across R9, leaving the voltage across CR4 at its original
voltage value (25 volts). CR4 consists of four Zener ERROR VOLTAGE.— Three sets of tests are
diodes with each diode operating in the breakdown made with a dc voltmeter at the three terminals

8-24
 Figure 8-18.—Automatic voltage regulator.

(numbered 54, 57, and 60) in figure 8-18, view C. These 4. Relocate the meter leads to measure line voltage
tests reveal several facts that explain the ERROR V L and verify that it has the same value (25
volts) as VR, when VE is zero.
VOLTAGE (VE) produced across terminals No. 54 and
No. 57 (fig. 8-18, view D). To use the dc voltmeter, use his will be for this measurement only. If resistor
R11 is readjusted to produce, for example, either a 27-
the following procedure:
or a 23-volt reading for V L, then VE has a numerical
1. Connect a dc voltmeter to the VE terminal. value of 2 volts. However, polarities are reversed.
Disregard meter-polarity connections since
The two conditions that may cause a change to the
some of the performance tests will cause the
excitation voltage by the automatic voltage regulator are
meter to read downscale when the polarity (of given in table 8-4.
the error voltage) reverses.
Table 8-4.—Effects of Changes to VL and VR
2. Initial changes in the amount of VE are made by
adjusting the slider on VOLTAGE ADJUSTING
RHEOSTAT R11. A slider position of R11 will
be found where VE registers zero.
3. Then, reposition the meter leads to verify that
the reference voltage VR (terminal No. 60 is
negative; No. 54 is positive) will always remain
at 25 volts regardless of generator output.

8-25
 MAGNETIC AMPLIFIER CIRCUITS.— The CW4 current changes so the core flux reaches saturation
essential parts of the two stages of magnetic amplifiers for part of the cycle, the gate-winding inductance
(figs. 5-16 and 5-17) consist of L5, L6, CR5, CR6, R13, drops to a very low value for that part of the cycle. A
R14, and R15. portion of the supply voltage wave is then applied to the
Changes in generator voltage produce changes in load.
current in the comparison circuit. These are in the order STABILIZING CIRCUIT.— In any closed-loop
of milliamperes while flowing in the control winding, regulating system that contains several time constants
CW4 (fig. 8-17). It is necessary to amplify these initial
and has high gain, sustained oscillations would be
small currents so their effect is in the order of several
produced. Undesired oscillation is sometimes called
amperes in the final control windings of CW1, CW2,
hunting. To prevent hunting, a stabilizing falter circuit
and CW3 of the SCPTs.
(resistor R17 and capacitor C3 in figure 8-12, view A)
Two magnetic-amplifier gates (GW1 and GW2 as is used to remove the normal ripple from the exciter
shown in figure 8-17) function automatically and output voltage. Another network (resistor R18 and
alternately to regulate the flow of ac delivered by the
capacitor C4) stabilizes the exciter output voltage.
56-volt secondary of transformer T5. The automatic
Nonlinear resistor R19 is used to suppress abnormally
regulation is achieved by saturating and&saturating the
high transient voltage that may appear across the field
flux in the cores of GW1 and GW2. The degree of flux
at any moment in each core is determined by the rectifier CR1.
previously described conditions of dc flow in the control REACTIVE DROOP COMPENSATION
winding, CW4. CIRCUIT.— Current transformer T4 and resistor R8
The flow of gated ac and its conversion into dc are used to obtain the generator-drooping characteristic.
pulses in another control winding (CW5 of the power The vector diagrams for this circuit are shown in figure
amplifier L6), is readily traced by inspection of the 8-19, views A and B. Figure 8-19, view A shows the line
arrows in figure 8-17, views B and C. These arrows voltages and currents for real and reactive loads. Figure
alongside the conductors and rectifier elements are in 8-19, view B shows the voltages on the secondary of the
the direction of electron flow during one half cycle in transformer T6, along with the IR (voltage) drop
figure 8-17, view C. The control winding current can
(produced across resistor R8 because of its current from
be changed until the full supply voltage is applied to the
the secondary T4, called I4).
load In this way, a control winding in each stage of the
several saturated cores controls the output from the
magnetic amplifier.
The series resistors R14 (fig. 8-17) and R15 (fig.
8-16) are adjusted so each amplifier operates in the
center of its saturation curve.

Inductor L7 (fig. 8-17) is used to assure smooth

continuous control of the second-stage amplifier.

Transformer T5 is used to supply power to the two

magnetic amplifiers. It is also used to supply control
current when it is operating in manual control.

A control winding would function to change its flux

by means of either dc pulses or filtered dc. Control
winding CW4 employs filtered dc by using capacitor Cl
(fig. 8-18) in the sensing circuit.

If, in figure 8-17, view B, the supply voltage (from

transformer T5) is applied to the gate winding in series
with its CW5 load, most of the voltage drop is across the
gate winding (and very little voltage drop is across the
CW5 control-winding load), provided the flux in the L5
core never reaches saturation. If the control-winding Figure 8-19.— Vector diagrams of reactive droop circuit-

8-26
 For an in-phase, real load, this I 4 R8 voltage drop Maintenance
shortens vector 01’ but lengthens vector 02’ (dashed
lines). The average of the three vectors remains The static regulator has no moving parts. Its
essentially constant. However, for a reactive load the I4 components are extremely rugged; therefore, little
R8 voltage drop lengthens vectors 01’ and 02’ (dashed maintenance besides preventive maintenance is
lines) and increases the average of the three vectors.
required. Some of the actions you should take are as
The regulator senses this higher voltage and reduces the
follows:
generator voltage. It does this by giving the generator
a drooping characteristic for reactive loads. Since the
• Ensure that the regulator is kept clean and
average of the three vectors 01’, 02’, and 03’ did not
internal connections remain tight.
change for a real load, the generator output should
remain essentially constant. • Protect all parts from moisture-this is an
essential action, especially when selenium rectifiers are
The amount of reactive droop can be increased by
involved. Exposure to moisture or mercury compounds
increasing the resistance of resistor R8. You should
make sure that the resistance is 2 ohms or more. will destroy selenium cells.

• When you replace new rectifier units in CR4,

CR5, or CR6, don’t overheat their leads when soldering.
Manual Operation
To prevent overheating, use a low-temperature solder
(rosin core). Attach a small heat sink, such as an
To start the static excitation and voltage regulation alligator clip or long-nosed pliers, between the rectifier
system equipment to run in manually, you should use
and the attached lead where the soldering occurs. This
the following procedure:
will prevent damaging heat from reaching the rectifier
1. Set the manual control rheostat R7 for minimum cell.
volts (fully counterclockwise).
• If it is necessary to apply a high-potential test to
2. Set the control switch S1 on MANUAL. the exciter or generator using a megger, you should short
3. Hold the FLASHING SWITCH S2 in the out all rectifiers with clip leads. High-potential tests are
FLASH position until the generator starts to discussed in the NSTM, chapter 300.
build Up.
4. Adjust the manual control rheostat R7 to obtain
SPR-400 LINE VOLTAGE
the proper generator voltage.
REGULATOR

Automatic Operation The SPR-400 line voltage regulator (fig. 8-20) is a

general-purpose, automatically controlled ac line
regulator. It ensures precision voltage regulation for
To operate the system in AUTOMATIC, bring the
line, load, frequency, and power factor variations in
system up in MANUAL control as just described, then
proceed as follows: single or three-phase (delta or wye connection) circuits.
There are several designs of line voltage regulators
1. Turn the control switch S1 to the AUTO position available. The operation described in the next section
2. Adjust the voltage-regulating rheostat R11 to will cover a typical design. The line voltage regulator
obtain the proper voltage. is designed around the use of the silicon controlled
rectifier (SCR). The SCR acts as a switch when a
NOTE: Never leave control switch S1 in an
intermediate position between MANUAL and control voltage is applied to it.
AUTOMATIC.
OPERATION
The control switch S1 has an emergency shutdown
feature when placed in its OFF position. This can be
used to quickly de-energize the generator in case of an The voltage regulator is installed in series with the
emergency. load, which requires a precise] y regulated power supply.

8-27
Figure 8-20.—SPR-4OO line voltage regulator.

8-28
The unit shown in figure 8-20 controls a single-phase 5. Autotransformer control windings receive dc
circuit. The input is at terminals X1 and X2 on terminal current later in each half cycle and the potential
board 1 (TB1). Regulated output is from terminals Y1 at Y1 and 1 will decrease.
and Y2 on TB1. Regulation is achieved by controlling
If line potential at Y1 and 1 decreases too far, then
the two autotransformers, T1 and T2.
the following events will occur:
An acceptable waveform is ensured where one side
of the transformer output goes to a harmonic filter via 1. Q4 will conduct less and Q3 more.
terminal 1 on TB1. The filter consists of the inductor 2. Q2 will now conduct more and charge Cl faster.
L2 on TB6 and the parallel capacitors C6, C7, and C8.
3. Q1 will now fire earlier in each half cycle and
Voltage from terminals Y1 and 1 on TB1 drives the gate the SCRs earlier.
rectifier bridge consisting of CR1, CR2, CR3, and CR4,
4. Control windings in the autotransformer receive
on the circuit board. This bridge provides dc power for
dc current earlier, decreasing autotransformer
the solid state components on the board
impedance and allowing line potential to
The operational sequence of the SPR-400 line increase.
voltage regulator is shown in table 8-5. Remember, the application of input power (across
terminals X1 and X2 of TB1, fig. 8-20) energizes the
Table 8-5.—Operation of the SPR-400 Line Voltage Regulator
two parallel operated autotransformers. The input
voltage is stepped up by an aiding winding (AID). This
is wound directly over the primary winding (PRI). The
voltage is then reduced to nominal output by an
opposing winding (OPP). The magnitude of induced
voltage in the opposing winding is varied by the level
of dc in the control windings (CON) from the SCRs.
The opposing and the control windings are separated
from the primary and the aiding windings by a magnetic
shunt. Increasing the dc in the control windings forces
the magnetic flux through the shunt. This decreases the
opposing voltage, and thus increases the output.

Items used to control the operation of the SCRs

(CR20 & CR21) in figure 8-20 are shown in table 8-6
below:
Table 84.—Description of Items Used in Controlling the
Operation of CR20 and CR21

For example, when line voltage increases, the

following events occur:

1. Q4 conducts more and Q3 conducts less.

2. Q2 in turn conducts less.
3. C1 will charge more slowly and Q1 will fire later
in each half cycle.
4. The SCRs will also be gated later in each half
cycle.

8-29
 An additional output voltage compensation is 30-KW MOTOR-GENERATOR SET
provided for cable loss when the stud of terminal Y2
passes through current transformer T5. It induces a The closely regulated MG set (fig. 8-21) consists of
signal in T5 proportional to the load current. a 450-volt, three-phase, 60-Hz, 50-hp, wound rotor
Adjustment of potentiometer R21 provides induction motor driving a 450-volt, three-phase,
compensation in this circuit. The potentiometer setting 400 Hz, 30-kW generator. The set is regulated and
compensates for the resistance in cables from the controlled by a voltage and frequency regulating system
regulator to the load. Once set, it doesn’t have to be (housed in the rotor resistor and regulator unit control
changed unless the cables (not the load) are changed. cabinets) and a magnetic controller with associated push
buttons and switches (located in the control cabinet).
MAINTENANCE The magnetic controller is a conventional size 3
across-the-line semiautomatic motor controller
Normally, voltage regulators require little (starter). The voltage-regulating system functions to
preventive maintenance, other than that described on the supply the proper field current to the generator so as to
MRCs. This is because the components are stable and maintain the generator output voltage within plus or
nonwearing with no moving parts (other than two minus one-half of 1 percent of rated output voltage for
potentiometers). However, you do need to make all load conditions. The frequency-regulating system
frequent inspections for dust, dirt, and moisture functions to control the speed of the drive motor to
accumulation. Also, you need to clean the equipment as maintain the output frequency of the generator within
necessary. plus or minus one-half of 1 percent of its rated value for
all load conditions. In addition, power-sensing
networks that function to eliminate speed droop with
CLOSELY REGULATED POWER increased generator loads and to maintain equal sharing
SUPPLIES of the load between paralleled generators are included.
Certain weapons, interior communications, and
other electronics systems aboard modem Navy ships Voltage Regulating System
require closely regulated electrical power (type 111) for
proper operation. Special closely regulated The voltage regulating system consists of a voltage
motor-generator (MG) sets supply the greater part of regulator and a static exciter, as shown in figure 8-22.
this power. Static-type converters are also used in some The output from the power section of the regulator, in
installations. conjunction with windings within the static exciter,

Figure 8-21.—Motor-generator set with control equipment.

8-30
 Figure 8-22.—Motor-generator set simplified block diagram.

controls the static exciter output. The static exciter 3. A power section
output, in turn, supplies dc (excitation current) to the The detector circuit includes a sensing circuit and a
generator field of the proper magnitude so as to maintain
three-phase bridge rectifier. The sensing circuit consists
the generator output voltage within specified limits
of three voltage sensing transformers with their primary
under all load conditions.
windings connected to the generator output and their
The static exciter consists of the following secondary windings connected to the bridge rectifier.
components: The bridge rectifier provides a dc output voltage that is
1. A saturable current-potential transformer proportional to the average of the three-phase voltage
(SCPT) outputs from the generator. This dc voltage is filtered
and fed to a Zener reference bridge in the preamp and
2. Three linear reactors (chokes)
trigger circuit.
3. A three-phase bridge rectifier unit
The dc output from the detector is compared with a
The SCPT contains (1) a primary winding constant Zener voltage in the reference bridge. The
consisting of both voltage and current windings, (2) a difference (error) voltage output from the bridge is
dc control winding, and (3) a secondary winding. The amplified by transistor amplifiers and fed to a
voltage primary windings are connected in series with
unijunction transistor circuit, which provides the pulses
the chokes across the generator output. The current
to trigger the SCRs in the power section. The SCR
primary windings are connected in series with the load,
output from the power section is fed to the control
and thus carry load current. The secondary winding
winding of the SCPT in the static exciter.
output is connected to the bridge rectifier unit, which
supplies the dc for the generator field. The SCPT During starting, generator field current is supplied
control winding is connected to the output of the voltage by a field flashing circuit, which is cut out after the
regulator. generator builds up an output voltage. At no-load
The voltage regulator consists of the following voltage, the primary windings of the SCPT are
components: energized through the choke coils and induce a voltage
in the SCPT secondary windings. The rectified output
1. A detector circuit of the secondary windings supplies the generator field.
2. A preamplifier (preamp) and trigger circuit This is the no-load field excitation.

8-31
 When a load is applied to the generator, load current regulator receives its input from a special type of
flows through the SCPT primary current windings frequency-sensing transformer whose voltage output
causing a flux, which combines vectorially with the varies linearly on changes in generator output
primary voltage windings flux to induce a voltage in the frequency. This input is rectified, filtered, and
secondary windings. Thus, any change in generator compared in a Zener reference bridge, and the bridge
load or load power factor is automatically compensated output is amplified by transistor amplifiers. The
for. This arrangement, without the use of the voltage amplified detector output (which represents the output
regulator, would hold the generator output voltage fairly frequency of the generator) is fed to the preamp and
constant under all load conditions. trigger section.

The voltage regulator is necessary, however, for the The detector output is further amplified in the
high degree of regulation required. The voltage preamp and trigger section, and this amplified output is
regulator acts as a fine control by effectively varying the used to control three pulse forming networks, which
coupling between the SCPT primary and secondary provide trigger pulses for SCRs located in the starter
windings. circuit.

The SCRs in the starter circuit (controlled by the

Frequency-Regulating System weak trigger pulses from the preamp and trigger section)
provide output pulses of sufficient magnitude to fire
The frequency-regulating system consists of a other SCRs located in the motor rotor control unit. The
motor rotor control and resistor unit and a frequent y output of the SCRs in the motor rotor control unit is fed
regulator. The detector circuit of the frequency through three large resistors (about 3,000 watts). These

Figure 8-23.—Static converter, front view.

8-32
are connected in the wound-rotor circuit of the drive Transformer Rectifier
motor.
Any change from the normal generator output The transformer rectifier unit (fig. 8-24) is an
frequency will cause the frequency-regulating system to autotransformer and a three-phase, full-wave, bridge
rectifier. The rectifier output is faltered and fed through
increase or decrease the rotor current, allowing the
choke coils to the static inverters. The choke coils limit
speed of the drive motor to compensate for the change.
the voltage appearing across the inverter SCRs.
Thus, the output generator frequency is maintained
constant by maintaining the speed of the directly
connected drive motor. Oscillator Circuit

The oscillator circuit (fig. 8-24) provides the pulses

STATIC CONVERTER
for firing the SCRs in the main inverter. This circuit
consists of a unijunction transistor oscillator that
The static converter (fig. 8-23) converts 450-volt, provides pulses at a rate of 800 per second. These pulses
three-phase, (50-Hz power to 120-volt, three-phase, switch a bistable (flip flop) transistor multivibrator
400-Hz power for use as a shipboard closely regulated circuit whose output supplies the primary of a
power supply. The converter automatically maintains transformer. The transformer output (which is a square
the output voltage and frequency within plus or minus wave) is amplified by a transistor push-pull circuit and
one-half of 1 percent of rated value for all load fed to the primary of the oscillator output transformer.
conditions. This high degree of regulation is maintained This transformer has a separate secondary winding for
even though the input voltage and frequency may vary each main SCR in the main inverter. The output of these
as much as plus or minus 5 percent of rated value. The secondary windings, fed through a differentiating circuit
450-volt, 60-Hz input is stepped dowm rectified, and fed (which converts the square waves to pukes), is used to
to two static inverters. Each static inverter contains two fire the SCRs. Each SCR being fired from a separate
main SCR groups consisting of two SCRs in series. The secondary winding ensures simultaneous firing of the
inverter outputs are fed to Scott-connected transformers SCRs in series. The phasing of the secondaries allows
to produce the three-phase output. A simplified block firing of opposite SCRs at 180-degree intervals for
diagram of the converter is shown in figure 8-24. proper inverter action.

Figure 8-24.—Static converter, simplified block diagram.

8-33
Phase Control Circuit
The phase control circuit (fig. 8-24) contains
components and circuits (similar to those in the
oscillator circuit) that function to control the firing of
the SCRs in the teaser (secondary) inverter and maintain
the proper phase relationship between the outputs of the
two inverters.

Voltage Regulators
The voltage regulator circuits (fig. 8-24) regulate
the converter output voltage by controlling the firing
time of the main SCRs in each inverter. The output of
a transformer connected across the converter output is
rectified to produce a dc signal that is proportional to the
converter output voltage. This signal is filtered and
compared in a Zener reference bridge to produce an
error signal output when the converter output voltage
varies from normal. This error signal is used to fire the
inverter control SCRs, which in turn, control the firing
time of the main SCRs.

Control Power Supplies

The converter (fig. 8-24) contains two control
power supplies (one for each inverter), which supply
regulated +30 volts dc to the various converter circuits.
The input to the power supply transformer is taken from
the 450-volt ac line. The power transformer output is
rectified by a full wave bridge rectifier and regulated by
a Zener diode regulator to produce the +30 volt dc Figure 8-26.—Block diagram of synchronizing monitor.
output.
NO-BREAK POWER SUPPLY SYSTEM
A no-break power supply system (fig. 8-25) is
designed to provide an uninterruptible electrical power
supply that is relatively constant in voltage and
frequency under all load conditions. The no-break
supply automatically takes over the power supply to a
load when the normal supply is interrupted by a change
infrequency or voltage. This type of system is required
by ships with equipment, control, or computer systems
that need an uninterrupted electrical power supply for
effective operations. It is presently being used with
ships using central operations systems.

The system uses an MG set, batteries, and

associated controls to provide its regulated output.
Either unit of the MG set can perform as a motor with
the other as a generator, thus permitting two modes of
operation.

MG MODE 1
In mode 1 operation of the MG set (fig. 8-25, view
A), the ac end of the set is being driven from the ship’s
Figure 8-25.—No-break power supply, block diagram. service power supply; and the dc end is a generator

8-34
providing power to charge the system batteries. This The synchronizing monitor does not automatically
motor-generator condition exists when the ship’s parallel two generators when it is connected to the
service power supply is meeting the voltage and system. The generators must be paralleled manually.
frequency requirements of the critical load. This is independent of whether or not the synchronizing
monitor is connected to the circuit. The function of the
MG MODE 2
synchronizing monitor is to prevent the manual
Mode 2 operation of the motor-generator set (fig. paralleling of two generators when the phase angle,
8-25, view B) represents the condition by which the set voltage difference, and frequency difference of the two
receives power from the batteries, and the ac end of the generators are not within safe limits.
set provides the power requirements for the critical load.
Mode 2 is referred to as the stop gap operation. The synchronizing monitor consists of the
following four main circuits:

SYNCHRONIZING MONITOR 1. The output circuit

The synchronizing monitor (fig. 8-26) monitors the 2. The phase difference monitor circuit
phase angle, voltage, and frequency relationship
between the 450-volt, 60-Hz generator and an energized 3. The frequency difference monitoring circuit
bus. Circuits within this panel energize a relay when the 4. The voltage difference monitoring circuit
phase angle (0) is between -30° and 0°, the voltage
OUTPUT CIRCUIT
difference is less than 5 percent, or the frequency
drift between an oncoming generator and an The output circuit (fig, 8-27) contains the K1 relay,
energized bus is less than 0.2 Hz. its power supply, and a set of contacts (circuit breaker

Figure 8-27.—0utput circuit.

8-35
Figure 8-28.—Synchronizing monitor.

8-36
closing switch contacts) in series with transistors Q1 and The operation of the output circuit is centered
Q2. The K1 relay provides an electrical interlock around the operation of Q1. In order to operate the
through the closing circuit of the generator circuit circuit breaker being monitored by the synchronizing
monitor (fig. 8-28) on.
breaker. The electrical interlock will prevent an
operator from electricaly closing the circuit breaker Two circuits affect the bias voltage of Q1:
unless the necessary conditions have been met. The
circuit breaker closing contacts must be open to energize 1. The phase difference monitoring circuit, which
the K1 relay. Also, Q1 and Q2 must be ON. With proper includes resistor R6. When a voltage of
circuit breaker line up, the first condition is met. The sufficient magnitude is developed across R6, the
monitoring circuits must provide the current signals to base to emitter bias of transistor Q1 is reversed.
This turns off Q1.
Q1 and Q2 to turn them on. The functions of the devices
in the output circuit are shown in table 8-7. 2. The voltage difference monitoring circuit. This
Table 8-7.—Devices in the Output Circuit circuit is connected across the base to the emitter
of transistor Q1. When transistor Q5 conducts,
this circuit disables Q1 by shorting the base to
emitter of Q1. This removes the bias reference
supply.
Q1 can conductor be biased on only when these two
circuits are off. The action by the Q1 transistor is similar
to that of a switch.

A transistor can be used to act like contacts that are

either closed or opened. This is done by using a large
enough base current signal that can drive the transistor
into saturation. At this point, the transistor acts like a
short circuit (equivalent to closed contacts). If the base
current signal is weakened, reversed, or eliminated, the
transistor then acts as an open circuit (equivalent to open
contacts).

The operation of the transistor circuit is as follows:

Relay K1 is energized when transistors Q1 and Q2 are
biased on, and circuit breaker switch contacts connected
between 2K and 2L are closed.

PHASE DIFFERENCE MONITORING

CIRCUIT

The phase difference monitoring circuit (fig. 8-29)

prevents energizing of the K1 relay if the phase
difference between the bus and the oncoming generator
is more than -30° and 0°. It does this by reducing and
comparing both input voltages, using its output to
control transistor Q1.

Look at the schematic in figure 8-30. The

secondary winding X1 and X3 of T2 and X1 and
X3 of T3 are connected so the output voltages of
T2 and T3 subtract from each other. For instance,
assume that the voltages are in phase, as shown in

8-37
 Figure 8-29.—Block diagram of phase difference monitoring circuit.

Figure 8-30.—Schematic diagram of a phase differnce monitoring circuit.

8-38
 Figure 8-31.—Input voltage to CR10 (in phase).

figure 8-31. When these voltages are in phase, the At a given magnitude, the voltage drop across
potential at points A and B (across rectifier CR10) in resistor R6 (fig. 8-28) overcomes the positive bias from
figure 8-30 will be the same, so no current can flow. base to emitter of transistor Q1 (because of Zener diode
Now assume that the energized bus and the energized CR8). The net result is a negative bias which shuts off
bus are 180° out of phase (fig. 8-32). Under these transistor Q1. This will prevent energizing of the K1
conditions the voltage at point A is at a maximum in a relay which prevents closing the circuit breaker for the
negative direction. This causes maximum current to oncoming generator.
flow in rectifier CR10. Filtering of the rectified current
FREQUENCY DIFFERENCE
is accomplished by resistor R7 and capacitor C4 (fig.
MONITORING CIRCUIT
8-30). Remember that when no phase difference exists
between the energized bus and the oncoming generator, The frequency difference monitoring circuit
the CR10 rectifier output is zero. A maximum output is prevents energizing of relay K1 if the frequency
developed when the difference is 180° between the two difference between the bus and the oncoming generator
signals. The CR10 output is applied across resistors R8 is more than 0.2 Hz. It does this by changing both
and R6. frequency signals into a beat frequency voltage

Figure 8-32.—Input voltage to CR10 (180° out of phase).

8-39
 Figure 8-33.—Block diagram of frequency difference monitoring circuit.

(fig. 8-33). It rectifies, filters, and reduces the beat 3. The beat frequency voltage is clipped by resistor
frequency voltage. It then uses the beat frequency R10 and Zener diode CR12 to a constant dc level
voltage in a timing circuit to fire an SCR. (fig. 8-35, view D)
Look at the schematic in figure 8-34. The 4. The signal is now sent to resistor R11 and diode
secondary windings X4 and X6 of T2 and X4 and X6 of CR13 (views A and B). Here, about 1 volt is
T3 are connected in such a manner that a beat frequency subtracted from the clipped beat frequency
voltage (heterodyne wave) is generated. This beat fre- signal (fig. 8-35, view E) to ensure the clipped
quency voltage is the difference between bus and oncom-
beat frequency voltage signal goes to zero when
ing generator frequencies (fig. 8-35, view A). Refer to
the original beat frequency goes to zero
figures 8-34 and 8-35 as you see how the circuit functions:
5. The clipped beat frequency voltage signal is
1. The beat frequency voltage is rectified by CR11 applied across base 1 and base 2 of unijunction
2. The resulting dc signal (fig. 8-35, view B) is transistors Q3 and Q4 (fig. 8-34). This signal is
filtered by resistor R9 and capacitor C5 (fig. also applied to the RC circuit, consisting of
8-35, view C) resistors R13A, R13B, R13C, and capacitor C6.

Figure 8-34.—Schematic diagram of frequency difference monitoring circuit.

8-40
 Figure 8-36.—Unijunction transistor.

Before continuing with the circuit description, you

need a brief explanation of the operation of a unijunction
transistor (fig. 8-36). A unijunction transistor has two
bases, B1 and B2, and one emitter. When the voltage
between B1 and the emitter rise to a certain percentage
of the voltage between B1 and B2, the unijunction
transistor will fire, The percentage is equal to emitter
voltage divided by the B2 voltage. In the case of the
unijunction transistors, it is equal to a nominal 62
percent. This means that when the emitter voltage is
approximately 60 percent of B2 voltage, both in
reference to B1, the unijunction transistor will fire. By
knowing that (1) Q3 and Q4 have different values for
the same voltage, (2) C6 has a definite charging rate
(determined by R9, R10, R13, and rectifier CR14), and
(3) that different beat frequencies have different time
intervals, you should have a basic understanding of how
the timing circuit operates.

In the following examples of how unijunction

transistors are find, the values used are arbitrary.

In the first example, (fig. 8-37), there is a difference

of 0.2 Hz in the beat frequency voltage. This causes a
time period of 5 time constants for 1 cycle. Within the
Figure 8-35.—Beat frequency voltages. 5 time constant period, the following events will occur:

Figure 8-37.—Firing sequence for Q4.

8-41
 • The voltage across Q3 and Q4 increases sharply • The 17 volts are applied across B1 and B2 of
and remains at 17 volts until the end of the cycle. unijunction transistors Q3 and Q4. It is also
applied across capacitor C7 and across the RC
• The 17 volts are applied across B1 and B2 of
circuit containing C6.
unijunction transistors Q3 and Q4, across
capacitor C7, and across the RC circuit • Capacitor C6 charges at the same rate as before
containing C6. (assuming 10.3 volts in 4 time constants). The
period of time for this cycle is only 2.5 time
• Capacitor C7 blocks rectifier CR14 and therefore
constants. Therefore, the voltage across C6 can
will maintain approximately 17 volts. The only
only reach approximately 6.5 volts within this
place C7 can discharge is through Q4, which has
time.
a very low leakage rate.
At the end of 2.5 time constants, approximately 17
The RC circuit containing C6 is charging at a volts are held across Q4 by capacitor C7, with a sharp
specific rate. If we assume that within 4 time constants decrease of voltage across B1 and B2 of Q3. When the
C6 reaches 10.2 volts, then the following events will voltage reaches approximately 10 volts, Q3 can fire
occur: because of its relative value of this voltage. Q4 still has
• The VE for Q4 will fire before Q3. approximately 17 volts across it.

• When Q4 fires, a voltage pulse is generated After Q3 fires and the beat frequency goes to zero,
across R15 (fig. 8-34) and is applied to the gate the time process again repeats itself.
of SCR1. You can see that different beat frequencies are
• SCR1 is then turned on. compared just as the differences were in phase and
voltage. The function of the frequency difference
• When SCR1 turns on, transistor Q2 in the output circuit is to energize relay K1 through the control of
circuit is supplied with a base current through transistor Q2, if the difference of the frequency of the
limiting resistor R16. bus and the oncoming generator is less than 0.2 Hz.
• This turns on Q2. When the beat frequency
voltage goes to zero, SCR1 turns off. VOLTAGE DIFFERENCE MONITORING
CIRCUIT
• The timing process then repeats itself.

In the second example (fig. 8-38), there is a The voltage difference monitoring circuit (fig. 8-39)
difference of 4.0 Hz in the beat frequency voltage. This prevents energizing of the K1 relay if the voltage
causes a time period of half the previous example. difference between the bus and the oncoming generator
Within this period of 2.5 time constants, the following is more than 5 percent. The circuit does this by doing
events occur: the following:

• The voltage across Q3 and Q4 increases sharply • Reducing and rectifying both input voltages (bus
and remains at 17 volts until the end of the cycle, and incoming generator)

Figure 8-38.—Firing sequence for Q3.

8-42
 Figure 8-39.—Block diagram of voltage difference monitoring circuit.

• Producing and delivering a sensing signal from voltage at T3. Transformer T3 steps the voltage down.
CR15 rectifies it, and R17 and C8 filter it.
each input
Zener diode CR18 is used to increase the sensitivity
• Comparing the difference in magnitude of the
of voltage dividers R20 and R21 in the bus signal circuit.
two sensing signals in a bridge circuit The Zener diode causes all the increase or decrease of
• Using transistor Q5 for an ON-OFF switch the bus signal voltage to appear across the voltage
divider. This also happens to voltage dividers R18A and
Look at the schematic in figure 8-40. You can see R18B, using Zener diode CR16. The resultant signal
that the bus voltage is stepped down by windings X7 and out of each voltage divider is the sensing signal. These
X9 on T2. The reduced voltage is then rectified by a sensing signals are then fed to a rectifier bridge
full-wave rectifier CR19 and filtered by R22 and C9. consisting of CRs 17A, B, C, and D. When the bus and
The same thing occurs for the oncoming generator the oncoming generator sensing signals are equal, there

Figure 8-40.—Schematic diagram of voltage difference monitoring circuit.

8-43
is zero voltage between the bridge (points A and B). A
difference between the bus voltage and the oncoming
voltage causes a voltage to exist across the bridge.
Connected between points A and B of the bridge is
the emitter and base of transistor Q5. The collector of
Q5 is connected to the base of Q1. The circuit is
completed from the emitter of Q1 to the emitter Q5. If
the voltage between A and B (across the bridge) is zero,
You can use signal tracers (such as dual trace
Q5 cannot be biased on. Therefore, the base to emitter
oscilloscopes) on transistor circuits if you observe the
of Q1 is not shorted out. If a voltage does appear across
precautions concerning the power supplies. Many
points A and B of the bridge, which can be caused by as
signal tracers use transformerless power supplies. To
little as a 5 percent voltage difference between the bus
prevent damage to the transistor, use an isolation
and the oncoming generator, Q5 will be biased on and
transformer.
short out the base to emitter of Q1. This will turn off
Q1 (fig. 4-21) and prevent energizing of relay K1. Multimeters used for voltage measurements in
Resistor R19 prevents small momentary changes in transistor circuits should have a high ohms/volt
voltage differences from turning on Q5 once relay K1 sensitivity to ensure an accurate reading. This should
has picked up. beat least 20,000 ohms/volt.
Ohmmeter circuits that pass a current of more than
1 milliampere through the circuit under test cannot be
SERVICING TECHNIQUES FOR used safely in testing transistor circuits. Before using
TRANSISTORIZED CIRCUITS an ohmmeter on a transistor circuit, check how much
current it passes on all range settings. Do not use any
There are many differences between transistorized
range that passes more than 1 milliampere.
and electron tube circuits from the standpoint of
servicing. For instance, you rely on your senses of sight, When used in the closely confined areas of
touch, and smell in the visual inspection of electron tube transistor circuits,
circuits. This is not as feasible in transistor circuits.
test prods are often the cause of accidental shorts
Many transistors develop so little heat that you can learn
between adjacent terminals. In electron tube circuits the
nothing by feeling them. High-frequency transistors
momentary short caused by test prods rarely results in
hardly get warm. Usually, if a transistor (except a
damage. However, in transistor circuits this short can
high-powered transistor) is hot enough to be noticeable,
destroy a transistor. Also, since transistors are very
it has been damaged beyond use.
sensitive to improper bias voltages, you must avoid the
In electron tube circuits, you often make a quick test practice of troubleshooting by shorting various points to
by the tube substitution method. You replace the tube ground and listening for a click. When you test
suspected of being bad with one you know to be good. transistor circuits, remember the vulnerability of a
In solid state circuits, the transistors are frequently transistor to surge currents.
soldered in. This makes the substitution method
impractical. Furthermore, you should avoid SUMMARY
indiscriminate substitution of transistors and other
semiconductors. You should test transistors with an In this chapter, you have learned about voltage and
approved transistor test set. frequency regulation. Within this area, you have
learned about types I, II, and III power, the principles of
Most good quality test equipment used for electron ac voltage control, the various types of voltage
tube testing can also be used for transistor circuit testing. regulators, closely regulated power supplies, and
You can use signal generators, both RF and AF, if the synchronizing monitors. You have also learned about
power supply in the equipment is isolated from the the various techniques used to service transistorized
power line by a transformer. circuits.

8-44
 CHAPTER 9

ELECTROHYDRAULIC LOAD-SENSING
SPEED GOVERNORS

This chapter contains a discussion about the An electrohydraulic governor may be operated as
operation and maintenance of electrohydraulic an isochronous governor; that is, at constant speed
load-sensing speed governors. If you do not have a regardless of load, provided the load does not exceed
thorough understanding of solid state circuitry, the limits of the prime mover. An isochromous
components, or terms, review the Navy Electricity and governor may also be used with speed droop; that is, as
Electronics Training Series (NEETS). The modules the load increases, the speed of the prime mover
that deal with solid state circuitry include the following: decreases. Speed droop permits paralleling with other
• Module 6, NAVEDTRA 172-06-00-92 generators that have dissimilar governors or paralleling
with an inifinite bus (such as shore power).
• Module 7, NAVEDTRA 172-07-00-92
The operation of a typical electrohydraulic
• Module 8, NAVEDTRA 172-08-087 load-sensing governoring system may be generally
• Module 9, NAVEDTRA 172-09-00-85 described as follows:

1. The throttle that controls the prime mover fuel

LEARNING OBJECTIVES medium is operated by an electrohydraulic
actuator.
Upon completion of this chapter, you should be able
to do the following: 2. This electrohydraulic actuator responds to the
output of an electronic amplifier.
1. Identify some of the characteristics of
3. Generator speed and load signals are fed into the
electrohydraulic load-sensing speed governors.
electronic amplifier.
2. Identify the function of various components in
an electrohydraulic load-sensing speed 4. The electronic amplifier produces a power
governor. output that operates the electrohydraulic
actuator.
3. Identify the sequence of operation of EG-M
load-sensing speed governor through speed 5. The electrohydraulic actuator correctly
changes. positions the steam valve or throttle.

4. Identify the sequence of operation of the EG-R The speed signal is usually provided by a small
hydraulic actuator through speed changes. permanent magnet generator (PMG) or a permanent
magnet alternator (PMA). The PMG or PMA are driven
5. Identify the sequence of operation EGB-2P
electohydraulic load-sensing speed governor from the shaft of the prime mover controlled by the
during speed changes. governor. When used to control a ship’s service
generator, the speed signal is sometimes obtained by
6. I d e n t i f y t h e m i n i m u m m a i n t e n a n c e sensing the output frequency of the generator.
requirements for maintaining electrohydraulic
However, a loss of signal, which could be caused by a
load-sensing speed governors.
short circuit on the generator, is a disadvantage of this
Electrohydraulic load-sensing speed governors method. The speed signal is applied to a
have been developed for the ship’s service generators in frequency-sensitive and reference circuit in the
electrical systems that require closer frequency governor control unit. The output of this circuit is a net
regulation than that provided by mechanical-type error signal if there is any deviation from the set speed.
governors. Electrohydraulic governors have been used
successfully on steam turbine, gas turbine, and Stability of the prime mover is obtained by the use
diesel-driven generators. of electrical feedback circuits.

9-1
 Load-measuring circuits are used in the However, a motor generator or static converter will still
electrohydraulic governor to obtain proper load sharing be required for type III voltage control.
on each paralleled generator. Most governing systems
NOTE: Refer to chapter 8 of this TRAMAN to
are designed so that any change in load produces a identify the characteristics of type II and type III power.
signal that is fed into the electronic amplifier. This acts
to offset any anticipated speed change caused by load The electrohydraulic load-sensing governor used in
change. The load-measuring circuits of governors on all this chapter is made up of three separate assemblies (fig.
generators that operate in parallel are connected by a 9-1)—an EG-M control box, a speed-adjusting
potentiometer, and a hydraulic actuator. Depending on
bus tie cable. The governor maybe designed or preset so the control box and the type of service in which it is
that each paralleled generator will equally share the used, a load signal box and a resistor box may be
total load. If not, a load-sharing adjustment must be required
provided.
EGM SYSTEM
The steady state and transient frequency
The EG-M electrohydraulic governor system (fig. 9-
requirements for type II electrohydraulic governors 2) offers diversified work capabilities. Large or small
power can be met with of the type just described. prime mover governor requirements can be met by the

Figure 9-1.—Electrohydraulic load-sensing governor system components.

9-2
Figure 9-2.—EG-M electrohydraulic systems.

9-3
Table 9-1.—EG-M Electrohydraulic Governor Characteristics permanent magnet generator and is applied to the EG-M
control box. The control box compares this voltage with
a reference voltage. If there is a difference, it supplies
art output voltage that energizes the EG-R hydraulic
actuator. A pilot valve plunger in the actuator directs oil
from a remote servo. This increases or decreases the
steam that returns the turbine speed to normal.
The load signal box detects changes in load before
they appear as speed changes. It detects these changes
through the resistor box that develops a voltage from the
secondary of the current transformers. This voltage is
compared with the generator load output voltage. If a
difference exists, the load signal box applies a
proportional voltage to the control box.

The droop switch allows parallel operation of prime

use of the EG-3C, the EG-R, a hydraulic amplifier, and movers with similar governors, dissimilar governors, or
the EG-R hydraulic actuator. The characteristics of with an infinite bus (shore power). The circuit breaker
these governors are shown in table 9-1. provides a path for control load signals to other
paralleled units.
OPERATION
EG-R Hydraulic Actuator
Look at the block diagram of figure 9-3. It shows
the use of the EG-R actuator with a remote servo. The The EG-R hydraulic governor will be considered
input signal (voltage) is proportional to the speed of a next. Figure 9-4 shows a schematic arrangement of this

Figure 9-3.—Electrohydraulic load-sensing governor system, block diagram.

9-4
9-5
governor. You can see that in this application the EG-R
hydraulic actuator is coupled with a remote servo
piston. High-pressure lines provide the means of
connecting the actuator to the remote servo. Oil from
an external source enters the suction side of the oil
pump. The pump gears carry the oil to the pressure
side of the pump. This fills the oil passages and
then increases the hydraulic pressure. When the
pressure becomes great enough, the relief valve
spring force is overcome, and the relief valve
plunger is pushed down. This uncovers the
bypass hole and allows oil to recirculate through the
pump.
The linear movement of the power piston in the
remote servo, used in conjunction with the EG-R
actuator, moves the engine or turbine linkage to
increase or decrease the prime mover speed. The
EG-R actuator controls the flow of pressure oil
to or from the servo piston. Pressure oil from the
pump is supplied directly to one end of the buffer
piston. The other end on the buffer piston connects
to the underside of the servo piston. Pressure in
this hydraulic circuit always tends to move the
power piston up in the decrease fuel direction.
The power piston cannot move up unless the oil
trapped on top of the power piston is allowed to drain.
It is drained to the sump by raising the pilot valve
plunger.

When starting the prime mover, manual control of

the speed of the prime mover is necessary until an
input signal and power becomes available to the control
box.

A drive force is necessary to rotate the actuator

pump gears and provide a relative rotation
between the nonrotating pilot valve plunger and its
rotating bushing. Upon loss of the electrical
signal, the EG-R and EG-3C hydraulic actuator
can go to shutdown. This depends upon design
application.

The major parts of the EG-R actuator (fig. 9-4)

and their functions are shown in the following
table:

9-6
 The hydraulic actuator (fig. 9-4) controls the The following will occur if there is an increase in
position of the prime mover fuel or steam supply valve load:
through the flow of oil to and from the upper side of the
power piston in the remote servo. The output signal
from the electronic control box is applied to a two-coil
solenoid surrounding the armature magnet of the pilot
valve plunger. This produces a force, proportional to
the current in the coil, that moves the armature magnet
and, in turn, moves the pilot valve plunger up or down.
An electronic amplifier is housed in the electronic
control box (fig. 9-1). When a positive dc voltage is sent
to the actuator from the control box, the pilot valve
travels in a downward direction. If a negative dc voltage
is sent to the actuator from the electronic control box,
the pilot valve plunger will travel in an upward direction.

With the pilot valve plunger centered, no oil flows

to or from the upper side of the power piston. The
following will occur if there is a decrease in the load

Stability of the system is controlled by the electric

governor section. It is enhanced by the temporary
feedback signal in the form of a pressure differential
applied across the compensating land of the pilot valve
plunger. The pressure differential is derived from the
buffer system and is allowed to fade away, as the engine
returns to normal speed, by the needle valve.
The power piston and its piston rod are surrounded
by seal grooves. These seal grooves are used to ensure
that any leakage of pressure oil from the power piston
comes from a part of the hydraulic circuit where it will
do no harm.

Hydraulic Amplifier

The hydraulic amplifier is a linear pilot-operated

servo actuator. It is used where relatively large forces
are required to operate power control mechanisms, such
as turbine steam valves or the fuel control linkage of
The rate at which the pilot valve plunger is moved large engines.
by the pressure on top of the compensation land is When using a hydraulic amplifier in conjunction
controlled by the needle valve setting. It is adjusted to with the EG-R actuator, a remote servo piston is not
match the rate at which the prime mover returns to used. The various ports of the actuator (ports A, C, and
normal speed. E) are directly connected to the amplifier with

9-7
high-pressure lines. The control servo piston, which is 2. Port C- Actuator pump output pressure is
an integral part of the amplifier, is used in place of the connected to annular seal grooves in the control
remote servo piston to control the movement of the piston and piston rod bores, ensuring that any oil
hydraulic amplifier pilot valve plunger. leakage comes from a part of the hydraulic
The use of a three-way valve, a starting valve, and circuit where it does not adversely affect control
a yield spring are necessary starting aids. These will be pressure or oil flow.
discussed later.
3. Port E- Actuator control pressure tends to move
The hydraulic amplifier does not have its own oil the control servo piston upward (increase fuel or
pump. Consequently, operating oil pressure and supply steam).
must come from an external source (usually the prime
Pressure in the compensation or buffer port (port A)
mover lubricating system). The use of a starting oil
and the control port (port E) are constant at steady state
pump is necessary when the prime mover is being
started. Once the prime mover develops its own for all control servo positions. Control oil pressure at
pressure, this pump is secured. port E is approximately one-half the compensation oil
pressure at port A. The control oil pressure varies much
Refer to figure 9-5 for a schematic diagram of the
more than the compensation oil pressure during a
hydraulic amplifier. The control ports are connected to
transient. The variations in control oil pressure causes
correspondingly identified ports in the EG-R actuator
(fig. 9-4). Oil at these ports perform the following: the control piston to move.

1. Port A- Actuator buffer compensation system The control servo piston is connected to one end of
pressure always tends to move the amplifier a floating lever in the amplifier. Any change in position
control servo piston downward (decrease fuel or of the control piston is transmitted to the floating lever.
steam). The movement of the floating lever is transmitted to the

Figure 9-5.—Hydraulic amplifier schematic diagram.

9-8
pilot valve plunger. This controls the flow of oil to or the electric control (hydraulic actuator) or load on the
from the power servo cylinder and piston. prime mover.

The following will occur when the electrical control The following will occur when the electrical control
unit senses an underspeed condition: unit senses an overspeed condition:

In some applications the steam valve or fuel control

must be opened before starting the prime mover. If this
is necessary, you must use a three-way valve, a starting
valve, and a yield spring. The yield spring and starting
valve are an integral part of the hydraulic amplifier. The
three-way valve is an external component. An
additional tube connection must also be made on the
hydraulic amplifier. This provides a passage for starting
oil (which is developed from a hand pump or an
electric-driven oil pump) to move the hydraulic
amplifier pilot valve plunger on startup. This
connection allows oil (25 psi minimum) to be used to
raise the hydraulic amplifier’s pilot valve plunger and
direct starting oil to the power servo piston. This is
During an on-speed condition, the control signal to necessary since the EG-R hydraulic actuator is
port E is maintained at a given pressure and the amplifier inoperative on initial startup. The yield spring permits
pilot valve plunger is held in its centered position. This one end of the floating lever to move upward when
covers the oil control port. With flow of oil to the stinting oil is applied to the bottom side of the pilot valve
opening side of the power servo piston blocked, except plunger. You must turn the three-way valve to drain
to compensate for leakage, the power piston will after starting. Otherwise, oil will be trapped under the
maintain its position in relation to the speed setting of pilot valve plunger and render the amplifier inoperative.

9-9
 In this low-pressure starting-oil system, the starting At shutdown, spring force returns the plunger to the
valve minimizes the force acting on the closing side closed position.
(bottom) of the power servo piston. Starting oil
pressure within the range of 25 to 30 psi (typical) cannot
generate sufficient force on the opining side (top) of the EG-M Control Box
power piston to overcome the combined forces of low
oil pressure and return spring force on the closing side The EG-M control box is designed to provide the
of the power servo piston. control signal to the electrohydraulic transducer in the
In the shutdown position, the starting valve blocks hydraulic actuator.
the flow of starting oil to the closing side of the power
As shown in the block diagram of figure 9-6, the
piston. It also simultaneously opens the area to drain.
control box has three inputs. One is from the load signal
When the prime mover starts and the normal supply box and will be discussed later. The other two are from
pressure (prime mover oil pressure) becomes greater the PMG and the speed setting (reference)
than the starting oil pressure, the following actions will potentiometer.
occur:
The input from the PMG is applied to the speed
section where it is converted into a negative dc voltage.
This voltage is proportional to the speed of the turbine.
The positive reference voltage (speed control) is
established by the speed-setting potentiometer but is
developed internally.

The outputs of the speed section and the speed

reference section are compared. If equal and of opposite
polarity, no signal is applied to the amplifier section. If
the speed of the turbine changes, there is a
corresponding change in the signal from the PMG. This
causes a change in the output of the speed section. An
error voltage is then applied to the amplifier section.
This is amplified and sent to the hydraulic actuator.
Some output is fed back through the stabilizer section
to keep the system from overreacting.

The schematic representation of the control box

(fig. 9-7) is a simplification of the actual amplifier and
is useful in describing its operation.

Figure 9-6.—EG-M control box, block diagram.

9-10
 Figure 9-7.—EC-M control box, simplified schematic.

If the speed-setting potentiometer is adjusted to This steam increase causes the turbine to increase
increase speed, the following actions will occur: speed. The negative speed signal increase counteracts
the previous positive speed signal increase. A new
steady-state condition of essentially zero voltage is then
reached both at the summing point and the actuator.
To further explain the function of the amplifier and
its stabilizing feedback network, refer to the voltage
waveforms of figure 9-8 as well as the schematic of
figure 9-7.
Assume that a step input voltage signal is applied to
the summing point of the amplifier, as shown on curve
1 (fig. 9-8). If the feedback circuit is disconnected at
point I (fig. 9-7), the output voltage for this condition
(without feedback and stabilization) will be very high.
This is shown in curve 2 (fig. 9-8). This will cause the
turbine to hunt excessively. The gain (output voltage
divided by input voltage) is very high in this condition.
Assume that the feedback network is reconnected at
point I, and the stabilizing network is disconnected at
point J. In this case the output signal from point D is fed
through the stability potentiometer to the base of
transistor Q2 (point E). This reduces the amplifier gain.
In response to the step input of curve 1, an output voltage
for this condition (feedback connected but without
stabilization) is obtained (curve 3, fig. 9-8).
Earlier, we stated that the output voltage at point D
and at the actuator increases in response to an increased
positive potential at the summing point of the amplifiers,

9-11
 The stabilization signal is obtained through the use
of a capacitor. With capacitor C1 disconnected at
point J (fig. 9-7), the negative feedback effect
reduces the gain (curve 3, fig, 9-8). When the
circuit is reconnected at point J, the capacitor
temporarily diverts some of the feedback signal away
from point E during the charging period of the
capacitor.

In response to the input voltage (curve 1, fig. 9-8),

the initial output voltage of the amplifier goes to a high
level (curve 4, fig. 9-8) at the first instant the signal is
applied and the feedback signal is varied. As the
capacitor charges, the voltage comes down on the
curved portion of the line. It levels off at approximate] y
the same level as curve 3 when a steady-state condition
is reached. The shape of curve 4 is determined by an
RC time constant. R is adjustable by the stability
potentiometer. The normal response of the amplifier to
an open loop test (fig. 9-8) produces an output voltage
waveform characteristic of curve 4. This is in response
to the input voltage of curve 1.

Load Signal Box

The load signal box (fig. 9-9) enables the

Figure 9-8.—Voltage relationships. governor system to respond to generator load
which causes the turbine speed to increase. Resetting of changes, as well as to speed changes. Load changes are
the amplifier is now achieved by the following actions: detected and responded to before they appear as turbine
speed changes. This minimizes speed change
transients.

The load signal box converts a three-phase input

signal (from the generator leads through the resistor
box) to a positive dc voltage. This voltage is
proportional to the kW load on the generator. The
voltage is applied to the load pulse section and the
paralleling network. When operated with dissimilar
governors, the droop and load pulse sections are used.
The droop switch determines the operating mode for
which the system is set up.

SINGLE GENERATOR OPERATION.— Look

at the simplified schematic of the load signal box in
figure 9-10. Input signals for the load signal box are
taken from the secondary of the generator current
transformers and developed in the resistor box. The
resistor box contains three resistors (one for each phase).
The voltage input is applied to transformer T2 and
compared to the generator voltage phase. This is taken
from the generator line, stepped down, and applied to
transformer T1. If both voltages are in phase, they will
cancel. Therefore, no output will appear. If they are out
of phase (the load is changing), a voltage in proportion

9-12
 Figure 9-9.—Load signal box, block diagram.

to the generator load will be rectified by CR1 and CR2. The amplitude of the signal can be varied by the
Although only one phase is shown in figure 9-10, each GAIN ADJ. potentiometer. A variable pulse output is
phase is compared. The comparison circuitry is developed by the charge/discharge time of C1 through
identical to that shown. the LOAD PULSE ADJ. potentiometer.

Figure 9-10.—Load signal box, simplified Schemstic.

9-13
 The load pulse signal is initially maximum and between the hydraulic actuator and the turbine is free
gradually decreases to zero. Figure 9-11 represents load from binding or lost motions. If the linkage is proper,
pulse signals in response to load changes. The signal is check the voltage regulator for proper operation. If
of the proper polarity to set the steam valve in the right these checks do not reveal the cause of the speed
direction to compensate for the change. The output variation, the governor is probably faulty.
signal is applied to the summing point in the EG-M
In troubleshooting the governor system, first check
control box (fig. 9-7).
the voltage across the input to the hydraulic actuator.
PARALLEL OPERATION WITH OTHER EG This should be done with the system running on speed
GOVERNOR SYSTEMS.— When the load signal box and set for single operation. If the voltage is not correct
is used with other EG governor systems, the operation (+0.5 volt dc to -0.5 volt dc) and cannot be set within
is the same as for single operation (fig. 9-10) except for range by the centering screw in the actuator, or if the
a closed circuit breaker (not shown). The closed circuit voltage fluctuates more than +0.25 volt dc and cannot
breaker connects the paralleling lines. This enables the be stilled by the GAIN ADJ. or the STAB. ADJ., the
load signal box to provide the same signal information control box may be defective.
to the control box of all the parallel units.
To bench test the control box, disconnect it from the
PARALLEL OPERATION WITH DIS- load signal box. Use a three-phase power supply instead
SIMILAR TYPE GOVERNOR SYSTEMS.— For of the normal supply. Instead of the speed signal, apply
operation with dissimilar type governor systems, a frequency oscillator output signal set to the rated speed
the droop switch must be turned on (down position frequency of the PMG (fig. 9-7). Use a resistive load
in fig. 9-10). This shorts out the paralleling lines so instead of the actuator. If an oscillator is not available,
that the parallel units are effectively not connected you can manually control the turbine-generator set to
to the load signal box. The signal to the control box provide the PMG signal.
is fed by the DROOP ADJ. potentiometer. This
adjustment compensates for differences in The converter section is working properly if, after
generator ratings and the reactive load carried by removing the amplifier section, the voltage at the
them. collector of Q2 (fig. 9-7) is correct (6 volts dc at rated
speed). If this is correct, place the amplifier back in the
MAINTENANCE circuit. The voltage across the resistive load
should be about zero volts. If not, the amplifier section
is faulty.
Governor faults are usually revealed in turbine
speed variations. However, a check of the system is If the trouble is a change in unit steady-state speed
necessary since not all speed variations are caused by a as the load is changed, check the voltage across the
faulty governor. actuator input under different load conditions. If the
Check first to determine that the changes are not a volt age is the same at both loads, the control box may
transient result of load changes. If the load is constant, be defective. If the voltages differ by more than 0.2 volt
hold an inspection to see that the operating linkage dc, the actuator is probably faulty,

The source of most troubles in the hydraulic

actuator or valve operator is dirty oil. Grit and other
impurities may be introduced into the system with the
oil or may form when the oil begins to break down
(oxidize) or become sludge. The moving parts within
the actuator and valve operator are continually
lubricated by the oil within the units. Thus, grit and
other impurities can cause excessive wear of valves,
pistons, and plunger. This can cause these parts to stick
or freeze in their bores.

For the remainder of this chapter, we will discuss

the EGB-2P governor/actuator and the 2301 load and
Figure 9-11.—Comparison of load pulse signals to load speed-sensing control, which are used to form another
changes. system.

9-14
 EGB-2P
GOVERNOR/ACTUATOR to drive a common load. In such installations, one
electric control can be used for two or more
The EGB-2P (fig. 9-12) is a proportional actuator proportional actuators wired in series with the
with a ballhead backup governor. The proportional control’s output. This furnishes the same input signal
actuator’s terminal (output) shaft position is directly to each actuator. Since each actuator receives the same
proportional to the magnitude of the output signal from signal, their output shafts take the same position. This
the electronic control unit. The uses and functions of a gives each engine the same fuel.
proportional actuator are different and distinct from Externally the EGB-2P is similar in size and
integrating types of EG actuators. To have a correct
appearance to the EGB-2C actuator. Internally, each
governoring system, you must use the EGB-2P
has two sections. These are the ballhead governor and
actuator with the 2301 or similar integrating electronic
electric actuator section. The ballhead governor section
control. By comparison, the EGB-2C is an integrating
actuator with the companion EG-A control box being acts as a backup governor in event of failure of the
basically a proportional amplifier. electric control. The electric actuator section is
different in function and construction. The actuator
Proportional actuators can be used in the same section of the EGB-2P includes feedback linkage from
type of service as other actuator models. They are its power piston to its pilot valve. This gives the
particularly well suited to engines operating in tandem proportional feature to the actuator.

Figure 9-12.—EGB-2P governor actuator.

9-15
 The proportional actuator requires a continuous EGB-2P governor/actuators are available with the
electric input signal. This is in contrast to the nominally terminal shaft extending from either or both sides of the
zero input signal under steady-state conditions for case. They can be furnished with the speed-adjusting
integrating-type actuators. Woodward 2301 electric shaft (for the ballhead governor section) extending on
controls are used to furnish the control input signal for either side. However, most units use a speed-adjusting
the proportional actuator. The exact 2301 control used screw in the top cover. They omit the speed-adjusting
depends upon the operating scheme of the installation. shaft entirely.
Control assemblies are available to sense speed,
OPERATION
frequency, load, and other combinations.

The following are the essential elements of the The schematic arrangement of the EGB-2P is shown
actuator section of the EG-B2P; in figure 9-13. The parts are in their relative positions
during normal operation. Oil enters the unit through
• Electrohydraulic transducer, which directs either of the two inlet holes in the side of the base. The
pressure oil to and from the power piston to actuate the oil passes from the suction to the pressure side of the
fuel or steam control mechanism. It consists of a pump. After filling the oil passages, the pump builds up
solenoid attached to the pilot valve plunger. the oil pressure. When the pressure is high enough to
overcome the relief valve spring force, it pushes the
• Pilot valve plunger, which controls oil flow to
relief valve plunger back to uncover the bypass hole. Oil
and from the power piston by positioning the control then recirculates through the pump.
land to add or drain oil to the actuator power piston.
Rotation of the pump in the opposite direction from
• Solenoid coil, which responds to the given output that shown in figure 9-13 closes the open check valves
of the electric control. This moves the pilot valve and opens the closed check valves.
plunger down, directing oil to the power piston.
The loading piston positions the terminal shaft.
• Power piston, which moves the terminal shaft of Constant oil pressure is applied to the upper side of the
the actuator. loading piston. This tends to move it in the decrease fuel
direction. Either the governor power piston or the
• Actuator terminal shaft, which is the attachment actuator power piston can move the loading piston in the
point for the engine or turbine fuel linkage. increase fuel direction. This is because the effective
Strict linearity of terminal shaft travel versus load area on which the control oil pressure acts is greater on
is not required. However, the linkage should be the power piston than on the loading piston.
arranged to give the same degree of linearity given In the event of an electrical failure, the unit goes to
conventional speed-sensing governors. minimum fuel. If the actuator goes to minimum fuel,
The centrifugal governor section has three apply a 9-volt dc supply to the transducer. This takes
the actuator toward maximum fuel. This allows the
operating adjustments. Once set, these adjustments do
governor to take control. Adjust the speed-adjustment
not usually require further adjustment. These settings
screw to give the desired steady-state speed. If the unit
are listed below.
has a manual override knob on the cover, push it down
1. Speed setting. An external adjustment used to and turn it to the right. This locks out the actuator
set the speed at which the ballhead governor will control.
control.
Actuator Control
2. Speed droop. An internal adjustment used to
permit parallel operation of units controlled by the The actuator’s pilot valve plunger controls the flow
ballhead governor. of oil to and from its power piston. The pilot valve
plunger is connected to an armature magnet. This
3. Needle valve. An external adjustment used to
magnet is spring-suspended in the field of a two-coil
stabilize the ballhead governor.
polarized solenoid. The output signal from the electric
The actuator section of the EGB-2P has no external control is applied to the polarized coil. This produces a
operating adjustments. The actuator uses oil from the force, proportional to the current in the coil. This tends
engine lubricating system or from a separate sump. It to force the armature magnet and pilot valve plunger
does not have a self-contained sump. down. The restoring spring force tends always to raise

9-16
9-17
the magnet and pilot valve plunger. When the unit is When the pilot valve plunger is pushed back to its
running under steady-state conditions, these opposing centered position, movement of the power piston,
forces are equal. The pilot valve plunger is then loading piston, and terminal shaft stop.
centered This means the control land of the plunger
Position of the actuator shaft is proportional to the
exactly covers the control port in the pilot valve bushing.
electric input signal to the actuator. An increase in the
With the pilot valve plunger centered, no oil flows to or
electric input signal caused by a decrease in engine or
from the power piston.
turbine speed or an increase in unit speed setting creates
An increase in engine or turbine speed or a decrease similar movements in the opposite directions.
in unit speed setting will cause the following actions to
occur:

This recenters the pilot valve plunger and stops

movement of the terminal shaft.

Governor Control

The governor pilot valve plunger controls the flow

of oil to its power piston. If the plunger is centered, no
oil flows through the pilot valve. The power piston is
As the actuator power piston moves down, the then stationary. The greater of two opposing forces, the
following actions occur: upward force of the flyweights and the downward force
of the speeder spring, moves the pilot valve plunger.
With the pilot valve centered, there is one speed at which
the centrifuged force of the flyweights is equal and
opposite to the speeder spring force.

With the speed setting of the governor set slightly

higher than the actuator, the centrifugal force of the
rotating flyweights is not sufficient to lift the pilot valve
plunger to its centered position. With the actuator
controlling, pressure oil is continually directed to the
underside of the governor power piston. This holds it
up against its stop. This is why the power piston of the
governor is against its stop when the actuator is
controlling.

With the unit running on speed with the governor

controlling, the pilot valve plunger is centered. If a load
is added to the engine, the following actions occur:

9-18
 continued increase of speed to normal increases the
centrifugal force developed by the rotating flyweights.
However, this increase of speed to normal does not
cause the flyweights to lift the pilot valve plunger above
center. Oil leakage through the needle valve orifice
equalizes the pressure above and below the
compensation land. This is at a rate proportional to the
return of the engine speed to normal. Then, as the
centrifugal force increases, the compensating force
decreases.
With the pressures above and below the
compensation land equalized, the buffer springs return
the buffer piston to its normal centered position.
When engine load decreases, the following actions
occur:

The terminal shaft is then rotated in the direction to

provide the additional fuel needed for the new load.
The movement of the buffer piston towards the
power piston partially relieves the compression of the
left-hand buffer spring.

Again, differential pressure across the

compensation land helps to recenter the pilot valve
plunger.
The speed at which the governor controls the engine
is determined by the loading or compression of the
speeder spring. This spring opposes the centrifugal force
of the flyweights. The standard EGB-2P has a
speed-adjusting screw in the top cover, as shown in
figure 9-13.
When the terminal shaft has rotated far enough to
satisfy the new fuel requirement, the pilot valve Speed Droop
recenters. This is caused by the differential force on the
compensation land plus the centrifugal force of the Speed droop is used in governors to divide and
rotating flyweights. This happens even though the balance load between engines or turbines driving the
engine speed has not returned complete] y to normal. same common load or driving generators paralleled in
Power piston and terminal shaft movement stops. The an electrical system. Speed droop is defined as the

9-19
Figure 9-14.—2301 load - and speed-sensing control.

9-20
decrease in speed taking place when the governor output (constant speed) or droop (speed regulation) operation
shaft moves from the minimum to the maximum for prime movers such as diesel or gas engines and steam
position in response to a load increase. It is expressed or gas turbines.
as a percentage of rated speed. Speed droop is provided Isochronous operation provides constant engine
in the EGB-2P through linkage, which varies the loading
speed for single unit operation or when several units are
on the speeder spring as a function of the power piston paralleled on an isolated bus. Droop operation allows
position. The change in speeder spring force for a given
paralleling of two or more units and provides speed
movement of the power piston is determined by the
regulation as a function of generator load.
position of the adjustable pin in the linkage between the
power piston and speeder spring. If the pin is on the Two engines driving a common load can be
same centerline as the speed droop lever pivot arm, there operated from one 2301 electric control by connecting
is no change in speeder spring force as the power piston the actuators in series. Since each actuator receives the
moves. The governor then operates as an isochronous same input signal, each engine receives the same
(constant speed) control. The further the adjustable pin amount of fuel.
is moved away from the pivot arm centerline, the greater
The output of the 2301 electric control provides a
the change in compression of the speeder spring for a
unidirectional continuous voltage level to the actuator,
given power piston movement.
which provides the desired speed and load relationship
With the unit operating under the electric control, called for by the input signals to the control panel. This
the speed droop feature is, in effect, inoperative. During type of output signal requires a proportional actuator.
such operation, the governor power piston remains in The proportional actuator contains a servo piston, which
the maximum position for all engine or turbine loads operates in proportion to the input voltage applied
(except possibly momentarily during transients).
The electric control also contains a ramp generator
Therefore, the speed droop linkage does not alter the
module which controls the rate of acceleration during
speeder spring compression when the actuator is
initial start-up. After the unit reaches set speed further
controlling.
control action from the ramp generator is blocked.

MAINTENANCE The load sensor provides either parallel isochronous

load sharing or droop operation for the unit.
As stated earlier, the source of most troubles in any
As with any governor, the engine should be
hydraulic actuator or governor stems from dirty oil.
equipped with a separate overspeed device. This
Valves, pistons, and plungers will stick and even freeze
prevents runaway (loss of control with maximum rpm)
in their bores, due to excessive wear caused by grit and
if a failure should render the governor inoperative.
impurities in the oil. If this is the case, erratic operation
and poor response can be corrected by flushing the unit
OPERATION
with fuel oil or kerosene. The use of commercial
solvents is not recommended as they may damage seals
The 2301 system is programmed to maintain preset
or gaskets.
speed- and load-sensing levels. These are in proportion
If the speed variation of the unit is erratic but small, to the capacity of the unit being controlled. For
excessive backlash or a tight meshing of the gears purposes of explanation, the system is divided into two
driving the unit may be the cause. If the speed variation sections: input and control (see fig. 9-15).
is erratic and large and cannot be corrected by
adjustments, repair or replace the unit. Input Section

2301 ELECTRIC GOVERNOR The input section consists of the following

components:
The 2301 electric control (fig. 9-14) is a
1. Load sensor,
combination of four modules mounted on a single
control panel. The control panel is the controlling 2. External magnetic pickup, and
portion of the 2301 system. The system is comprised of
3. Speed sensor.
the 2301 electric control (described here), a magnetic
pickup, current and potential transformers, and a These circuits detect and process the speed and load
hydraulic actuator. The system can provide isochronous input signals.

9-21
9-22
 LOAD SENSOR.— External three-phase current approximately ±4 percent from the internal SPEED
and potential transformers are used to monitor the setting.
generator load. Load sensor input transformers process
RAMP GENERATOR.— Ramp generator A3
the current signals (expressed as a voltage level
biases the speed signal to control the rate of acceleration
developed across burden resistors R1-R3) and the
of the prime mover from idle to rated speed. Closing
potential signals to compute the kW load on the
the external switch or contacts connected to TB1
generator. Rectifiers convert the ac voltage from the
terminals 14 and 15 starts the acceleration ramp.
transformers to dc. A voltage adder circuit adds the dc
Opening the switch or contacts returns the unit to idle
voltage of each phase and provides a signal
speed. Front-panel screwdriver adjustments set the
representative of the kW load.
LOW SPEED SETTING and ACCELERATE RATE of
The internal LOAD GAIN potentiometer applies a the ramp generator.
portion of the load voltage to the bridge circuit. When
connected to other units through paralleling lines, the MODE SWITCH.— This switch selects either the
bridge circuit compares this signal with that of the other isochronous or the droop mode of operation. This is a
units. This allows each unit to share equally in two-section ganged switch. The first section (a speed
proportion to its capability. switch) either connects the paralleling lines to the load
sensor (TB1-10) for isochronous operation, or it
The correcting signal of the load sensor is applied unbalances the load sensor bridge by shunting one leg
to the summing point to provide the load control to common (TB1-11). The second section (also a speed
function to the amplifier. switch) connects the load sensor output (A2TB1-5) for
isochronous or droop operation. In the isochronous
MAGNETIC PICKUP/SPEED SENSOR.— Ac
mode, the load sensor output is connected directly to the
input pulses from a magnetic pickup provide the speed
summing point. In the DROOP mode, the output is
input signal to speed sensor A4. The magnetic pickup
connected to the DROOP control potentiometer.
consists of a coil of wire wound around a permanent
magnet. This magnet pickup is mounted close to a DROOP CONTROL.— DROOP control A5R1
toothed gear, which is driven by the prime mover. As biases the engine speed to decrease speed as the load
the gear teeth pass through the magnetic field produced increases. This is accomplished by setting the external
by the permanent magnet, a step voltage (pulse) is mode switch to DROOP. This connects the DROOP
generated in the coil of wire. potentiometer in series with the load sensor output.

AMPLIFIER— The output signals from the load

Control Section
sensor, the speed sensor, the SPEED setting
potentiometer, and the ramp generator are applied to the
The control section consists of summing point input of amplifier Al. Amplifier Al
1. the SPEED setting control, amplifies the resultant input voltage to increase or
decrease fuel proportionally. Internal GAIN and
2. the ramp generator, RESET controls determine the magnitude and the
3. an external mode switch, response time of the amplifier. The complete control
system is a closed loop (sensors, amplifier, actuator, fuel
4. the DROOP control, and flow, prime mover speed, sensors), and the purpose is to
5. the amplifier module. match the electronic response time to the system
response time for stable operation.
These circuits combine to provide the control signal
to the actuator, thus controlling the speed of the prime
mover. DETAILED CIRCUIT DESCRIPTION
SPEED SETTING CONTROL.— The SPEED
setting control applies a variable dc voltage to the The following sections provide a more detailed
amplifier summing point. When a jumper wire is description of the 2301 electric control circuitry. These
connected to TB1 terminals 20 and 21, the SPEED detailed descriptions are keyed to the individual module
potentiometer on the panel sets the speed. schematics. The block schematic diagram, figure 9-15,
Disconnecting the jumper wire and connecting a 10-turn shows all the modules in relationship to one another
100-ohm potentiometer allows external speed control of including inputs and outputs.

9-23
Input Voltage Distribution Speed Setting Reference Voltage

The 2301 electric control operates with either a Since the speed setting input voltage determines the
24-volt dc supply or a 32-volt dc supply. The source of speed of the prime mover, a stable reference voltage is
this supply can be either a battery or a regulated dc necessary for stable speed control. Zener diode
power supply. A1A1VR1 provides a stable 6.6-volt dc at TB1 terminal
21 (fig. 9-15) for the speed-setting control.
Resistors R4 and R5 (see block schematic diagram
fig. 9-15) are current-limiting resistors for zener voltage Amplifier
regulators A1VR1 and A1VR2 (see amplifier schematic
fig. 9-16). When you are using a 24-volt dc supply, this Input signals from the various input and control
operating voltage is applied to TB1 terminals 12 (+) and circuits (fig. 9-16) are algebraically added together at
13 (-) (fig. 9-15). When you are using a 32-volt dc the summing point input to the amplifiler (A1TB1
supply, operating voltage is applied to TB1 terminals 25 terminal 5). The steady-state condition of the closed
(+) and 13 (-). Resistor R6 drops the +32-volt to loop (sensors, amplifier, actuator, fuel flow, prime
+24-volt dc before being applied to current-limiting mover speed, sensors) is a value approaching null
resistor R5. voltage at the summing point input to the amplifier.

Protection diode CR1, mounted on the panel, is in The speed-setting input voltage (positive) at A1TB1
series with the negative voltage supply lead (common terminal 10 is algebraically added to the speed sensor
to both the 24-volt and 32-volt dc supplies). The diode voltage (negative) at the summing point (A1TB1
protects the circuitry by reverse biasing if the input terminal 5). A resultant positive voltage causes input
voltage polarity should ever be reversed. transistor A1A1Q1 to turn on and conduct. This causes
the differential amplifier to become unbalanced. The
Voltage regulators A1VR1 and A1VR2 regulate the Q1A emitter potential decreases conduction through
24-volt dc to +9 and -9 volt dc with respect to center tap Q1B. The Q1B collector potential decreases
common (A1TB1 terminal 6). This +9 and -9 volt dc is conduction through Q2. Collector potential from Q1A
the regulated supply voltage for the 2301 electric control forward biases A1A1Q3, causing increased conduction
system. through Q3.

Figure 9-16.—Amplifier schematic.

9-24
 The differential amplifier is now set to call for an capacitor A1A1C4. As the time constant increases, reset
increase in fuel. Q1A and Q3 are turned on, and Q1B time increases. This increases stability by slowing the
and Q2 are at the threshold level. The differential response time.
amplifier remains in this configuration until the speed
A high-frequency feedback circuit consisting of
sensor input nulls out the speed- setting voltage level. A1A1R16/C8 and A1A1R19/C9 compensates for any
At that time the differential amplifier becomes balanced.
high-frequency interference that might be introduced.
As conduction increases through A1A1Q3, the Q3 Derivative capacitor A1A1C11 provides derivative
collector potential biases output amplifier A1A1Q4 for control action for the amplifier by effectively acting as
increased conduction. The Q4 emitter potential forward a short circuit to common for the feedback signal when
biases power amplifier A1Q1, turning A1Q1 on. Power there is a step change in the output voltage. This allows
amplifier A1Q1 saturates to clamp -9 volt to A1TB1 the amplifier to reach maximum gain momentarily.
terminal 3 and supply the current required by the Then the effect is dissipated exponentially to zero.
actuator coil.
For single actuator operation, A1TB1 terminal 8 is
System stability is derived by feeding a portion of connected to dc common terminal 6. For multiple
the output signal back to the amplifier input. GAIN actuator operation, terminal 8 is connected to the +9-volt
potentiometer A1R1 sets the gain of the amplifier by power supply at terminal 1.
varying the amount of inverse feedback. As the
amplitude of feedback increases, amplifier gain
Ramp Generator
decreases.

RESET potentiometer A1R2 sets the stability of the Ramp generator (fig. 9-17) A3 biases the speed
control loop by changing the reset time constant of the setting input signal to the amplifier module in either of
feedback signal. The time constant is the product of the two modes: a deceleration mode to a low speed or an
value of RESET potentiometer A1R2 and integrating acceleration mode.

Figure 9-17.-Ramp generator schematic.

9-25
9-26
 DECELERATION MODE.— With the external Biasing for the second amplifier is such that it
switch or contacts (connected to TB1 terminals 14 and operates as a saturation switch. The negative trigger
15) open, the positive voltage from A3A1R1 forward spikes saturate Q3 and hold Q3 saturated until the spike
biases current switch A3A1Q1. With Q1 turned on, -9 decays sufficiently below the threshold voltage to turn
volts are connected through Q1 to LOW SPEED Q3 off. This produces a pulsed output with the
potentiometer A3R1. The LOW SPEED potentiometer frequency determined by the engine speed and the pulse
sets the amount of negative speed-setting bias voltage width determined by the selected time constant. Zener
to hold the prime mover at the desired idle speed.
diode A4A1VR1 clamps the maximum pulse excursion
ACCELERATION MODE.— Closing the to 6.6 volts.
external ramp switch or contacts connected to TB1
terminals 14 and 15 connects -9 volts dc to timing As the engine rpm increases, so does the frequency
capacitor A1C1 and current switch A3A1Q1. This of the speed input signal (see fig. 9-19). The value of
reverse biases Q1 and stops the current flow through Q1. capacitance selected sets the speed range of the speed
This allows the right side of C1 to charge from -9 volt sensor to match the requirements of the engine. Higher
dc toward +9 volt dc his positive ramp voltage is rpm engines require a faster differentiator network time
applied through gate diode A3A1CR2 to the amplifier constant. This maintains the proper ratio between the
summing point. ACCEL potentiometer A3R2 sets the pulse width and the puke period (time between pulses).
charge time constant of the circuit, thereby setting the
acceleration rate of the ramp generator. The ramping The output from second amplifier Q3 is filtered by
output voltage continues in a positive direction until it a two stage RC filter consisting of R4/C2 and R5/C3.
reaches 0 volt dc As the ramp becomes more positive For all practical purposes, the filtered output voltage is
than 0 volt dc, gate diode A3A1CR1 forward biases and proportional to the engine speed (see fig. 9-19). If the
begins to conduct. This clamps the ramp generator engine speed decreases, the frequency of the
output to +0.6 volt dc At this time the prime mover differentiated spikes decreases. This increases the time
should be at or near rated speed and the reference between pukes. Since the pulse width is determined by
voltage at the summing point will be 0 volt dc. the differentiator time constant, the pulse width remains
the same. This decreases the average dc voltage level
from the filter circuit.
Speed Sensor
During normal operation the clipped sine wave
The speed input signal from the magnetic pickup is output signal from the first amplifier is coupled through
applied to interstage transformer A4T1 (see fig. 9-18). gate diode A4A1CR4 and charges integrating capacitor
Transformer T1 provides a 1 to 3 step-up ratio of the C1. When C1 charges sufficiently negative, fail-safe
speed input signal. The alternating input signal from T1 transistor Q4 turns on and saturates. This clamps the
alternately drives first amplifier A4A1Q1/Q2 into anode of VR2 at the dc common potential. In this mode
saturation and cutoff. This clipped sine wave output the negative fail-safe supply voltage, which is connected
signal is applied to the selectable time constant through the fail-safe jumper, is dropped across R7.
differentiator network.

Differentiator networks A4C1/A4A1R9 and R12

convert the clipped sine wave from the first amplifier to
corresponding positive- and negative-going spikes.
Capacitor A4C1 is selectable to set the proper time
constant for the particular engine speed for which the
2301 electric control is used. The value of capacitance
selected determines the decay time of the positive and
negative spikes.

The positive- and negative-going spikes are applied

to gate diode A4A1CR3. The gate diode passes only the
negative-going spikes and rejects the positive spikes.
These negative spikes trigger the second amplifier
A4A1Q3. Figure 9-19.—Speed sensor output voltage.

9-27
9-28
 In the event that the magnetic pickup fails (or before
initial start-up), capacitor C1 becomes discharged,
allowing fail-safe transistor Q4 to turn off.
When this condition occurs, the fail-safe supply
voltage reverse biases zener diode VR2. This clamps
the speed sensor output voltage at approximately -2.4
volts. This simulates a high engine speed to the
summing point to decrease the engine fuel supply to
minimum.

Load Sensor

In the load sensor (fig. 9-20) A2 monitors the

voltage levels from the external potential and current
transformers. From these input signals, the load sensor
computes the total kW load on the generator and
produces a dc voltage proportionate to the load
Figure 9-21 shows one phase of the load sensor and
the equivalent voltage circuits for 90° and 270°
transition through the sine wave. As shown, current
input transformer T4 can be represented by battery E3,
the value and polarity of which is dependent on load and During periods of no load, voltage at E3 is 0 V
sine wave transition. During the positive half cycle, the and the voltage developed across R1 and R2 is equal to
following actions occur: the voltage at E1 and E2.

Figure 9.21—Equivalent single-phase circuit.

9-29
 During no load there is no current signal and the load on the generator increases, the load voltage
consequently no voltage is developed across the current from the bridge circuit (terminal 12) increases
transformer. This results in a 0 volt load signal since the negatively. This negative voltage is applied to the
three phases cancel each other out. DROOP potentiometer which sets the amount of series
resistance. In this mode the negative load voltage biases
LOAD GAIN control A2Rl (fig. 9-20) is connected
the speed setting signal downward as the load increases.
in parallel with the voltage adder circuit. The output of
the variable LOAD GAIN control (represented as PARALLEL UNIT ISOCHRONOUS.— The load
variable voltage source E in fig. 9-22) is applied across sensor provides proportional load sharing when two or
the bridge circuit. This then is the load control signal more generating units are parallel in the isochronous
for this particular prime mover. mode. In this mode each load sensor compares the load
of its generating unit with the load of other units
A dc-droop circuit is connected across the output of
producing power and either increases or decreases fuel
the LOAD GAIN potentiometer and applies a portion of
to the engine to maintain its proportional share of the
this load voltage as bias to the output of the load sensor. load.
This counteracts any inherent droop in the overall
system. When the mode switches are set for isochronous
operation for a parallel engine combination, their load
An optional load pulse circuit (fig. 9-22)
sensor bridge circuits are connected together through
differentiates any sudden load voltage output from the
the paralleling lines (see fig. 9-23). In this mode of
LOAD GAIN control caused by a sudden load change.
operation, the bridge circuits are balanced with terminal
The load puke provides a lead signal to the amplifier
11 as a common reference point.
summing point and minimizes the off speed and
recovery time associated with large and sudden load When paralleling two or more units, each engine
changes. takes on its proportional share of the load by equalizing
SINGLE UNIT ISOCHRONOUS.— During the load voltages across the bridge network.
single-unit isochronous operation, the bridge circuit is As an example, assume that two units are paralleled
balanced; thus the load sensor output is 0 volt. Under The first unit has a 100-kW capacity and the second has
this condition the speed sensor maintains engine speed 50 kW. Unit 1 is operating at 75 percent capacity and
SINGLE UNIT DROOP.— Setting the external unit 2 is at rated speed with no load. The load sensor for
mode switch to DROOP connects AIR11 to dc common. both units is calibrated for 9 volts at full load. However,
This unbalances the bridge network, producing a E1 for unit 1 is 6.75 volts (9 volts x 0.75) and E2 for unit
2 is 0 volt (9 volts x 0.00), caused by the different load

Figure 9-22.-Basic load sensor, single-unit configuration.

9-30
 Figure 9-23.—Basic load sensor, parallel unit configuration.
conditions. This condition exists at the moment of MAINTENANCE
paralleling, causing an electrical imbalance between the
two load sensor bridge networks. Maintenance for the 2301 electric governor should
be conducted on a regular basis. The first step in the
procedure is to look for any obvious physical defects.
Missing, loose, or damaged electrical or mechanical
connections often result in more serious maintenance
problems if not corrected. Other maintenance
suggestions are as follows:

Transformers. Inspect all transformers for loose

or broken terminals. Check all mounting hardware.

Controls. Inspect all controls for loose mounting,

damaged wipers, or contacts and smoothness of
operation. Do not disturb the setting of a
screwdriver-adjusted control unless it is suspected of
being faulty.

Terminal blocks. Inspect all terminal blocks for

cracks, chips, or loose mounting hardware. Check all
wiring terminals for loose wires or lugs.

Printed circuit boards. Inspect printed circuit

boards for secure mounting and proper location in the
This continues until E1 equals E2 (4.5 volts) and unit. It is not advisable to remove circuit boards for the
both generators share the load proportionally. Unit 1 is sole purpose of inspecting them for physical damage.
producing 50 kW, and unit 2 is producing 25 kW for a Components mounted on printed circuit boards should
total power of 75 kW. be checked for secure mounting and poor electrical
connections.
The load sensors are only active during unequal
Wiring. Inspect all wiring for frayed or burned
had changes when a circulating current develops
leads. Insure that insulating sleeves are in place. Check
between the bridge networks. During an unequal
for loose or broken lacing in harnesses.
change, the bridge networks are electrical y unbalanced,
and the action is always toward proportional load When power is secured, dust and foreign matter can
sharing. be removed by brushing with a clean dry brush. Large

9-31
surfaces should be wiped with a clean, dry, lint-free SUMMARY
cloth. Compressed air at low pressure may be used to
After you have completed this chapter, you should
blow dust from hard to reach areas. When using
understand the basic function of electrohydraulic
compressed air for cleaning, always direct the first blast
governor control systems. There are many different
at the deck. This will blow any accumulation of types and variations in the components of the systems.
moisture from the air line. This chapter has dealt with only a few. When making
Use a nonlubricating electrical contact cleaner repairs on your system, always refer to the correct
when potentiometers have erratic control. technical manual.

9-32
 CHAPTER 10

DEGAUSSING

Degaussing is the method most used to reduce a The existence of magnetism far out in space was
ship’s magnetic field to minimize the distortion of the determined mathematically many years ago. The first
earth’s magnetic field. This, in turn, reduces the factual proof came with the launching of the Explorer
possibility of detection by these magnetic sensitive and Pioneer satellites in 1958 and 1959. Radiation
ordnances or devices. counters proved that the Van Allen belts, layers of
high-intensity radiation existing far out in space,
followed the predicted magnetic contours.
LEARNING OBJECTIVES
Project Argus also gave additional proof of the
Upon completion of this chapter, you should be able earth’s magnetic field in space. In August of 1958, three
to do the following: small 1.5-kiloton nuclear explosions were detonated
300 miles above the Falkland Islands in the South
1. Recognize the purpose of the degaussing Atlantic. In the virtual vacuum that exists at 300 miles
system. above the earth’s surface, free electrons, released by the
2. Identify the various coils used in the degaussing explosion, were captured by the earth’s magnetic field.
system installation. In less than 1 second, electrons spiralled from the
Southern to the Northern Hemisphere. Within an hour,
3. Identify the need for deperming. they had covered the entire magnetic field at 300 miles
4. State the procedures used when ranging a ship. altitude.

5. Recognize the differences between the types of Figure 10-1 shows the earth as a huge permanent
degaussing systems. magnet, 6,000 miles long, extending from the Arctic to
6. Recognize the marking system used in the Antarctic polar region. Lines of force from this
degaussing system installations. magnet extend all over the earth’s surface, interacting
with all ferrous materials on or near the surface. Since
A steel-hulled ship is like a huge floating magnet many of these ferrous materials themselves become
with a large magnetic field surrounding it. As the ship magnetized, they distort the background field into areas
moves through the water, this field also moves and adds of increased or decreased magnetic strength. The lines
to or subtracts from the earth’s magnetic field. Because of magnetic force at the earth’s surface do not run in
of its magnetic field, the ship can act as a triggering
device for magnetic-sensitive ordnance or devices.
Reduction of the ships static magnetic signature is
accomplished using the following means:

1. Degaussing
2. Nonmagnetic materials in construction
3. Controlling eddy current fields and stray
magnetic fields caused by various items of the
ships equipment

THE EARTH’S MAGNETIC

FIELD

The magnetic field of the earth is larger than the

magnetic field of a ship. The earth’s magnetic field acts
upon all metal objects on or near the earth’s surface. Figure 10-1.-Earth’s magnetic field.

10-1
straight, converging lines like the meridians on a globe, magnitude and direction for several representative cities
but appear more like the isobar lines on a weather map. in the Northern and Southern Hemispheres. As you look
at this table, you can see that the vertical component is
By convention, the positive external direction of the
positive in the Northern Hemisphere and negative in the
magnetic field of a bar magnet is from the north pole to
Southern Hemisphere. These component polarities
the south pole. However, lines of force for the earth’s
occur because lines of force leave the earth in the
field leave the earth in the Southern Hemisphere and
Southern Hemisphere and reenter in the Northern
reenter in the Northern Hemisphere. For this reason,
Hemisphere. For this reason, the upward field, in the
you can think of the polar region in the Arctic as the
Southern Hemisphere, is assigned a negative value; and
north-geographic, south-magnetic pole. The Antarctic
the downward field, in the Northern Hemisphere, is
polar region is then the south-geographic,
assigned a positive value. There are two areas of
north-magnetic pole.
maximum vertical intensity but opposite polarity—the
Look at figure 10-1. Here, you can see that the north and south magnetic poles. The vertical intensity
magnetic lines of force form closed loops, arching from at the magnetic equator is zero since the entire field is
the earth’s magnetic core to outer space, and then horizontal.
reentering the earth in the opposite hemisphere. Since
The vector sum of the H and Z components defines
all lines of magnetic force return to their points of origin,
the magnitude and the direction of the total field at any
they form closed magnetic circuits. It is impossible to
point on the earth’s surface.
eliminate the earth’s field; however, the effect a ship has
on the earth’s magnetic field may be lessened. The
purpose of degaussing is to prevent the ship from THE SHIP’S MAGNETIC FIELD
distorting the earth’s magnetic field. Some highly
developed techniques are used in degaussing. The magnetic field of a ship is the vector sum of the
ship’s permanent magnetic field and the ship’s induced
The rest of this chapter explains the fundamentals magnetic field. The ship’s magnetic field may have any
of degaussing and describes the operating principles of magnitude and be at any angle with respect to the
manual and automatic shipboad degaussing systems. horizontal axis of the ship.
Learning these knowledge factors will help the EM
stand watch at the degaussing switchboard operate the
PERMANENT MAGNETIZATION
degaussing equipment, and maintain the installed
degaussing system.
The process of building a ship in the earth’s
The magnitude and direction of the earth’s magnetic magnetic field develops a certain amount of permanent
field at any point may be resolved into components. magnetism in the ship. The magnitude of the permanent
These components are the horizontal (H) component magnetization depends on the earth’s magnetic field at
and the vertical (Z) component. Since the earth is the place where the ship was built, the material used to
spherical, an X and Y component would have little construct the ship, and the orientation of the ship at the
meaning; therefore, X and Y are combined into one time of building with respect to the earth’s field.
component, the H component.
The ship’s permanent magnetization is the source of
The angle of the field with the horizontal, the ship’s permanent magnetic field. This permanent
sometimes called the dip angle, may be easily magnetic field can be resolved into two factors:
determined by a dip needle. A dip needle is a simple
1. The vertical permanent field component,
two-pivot compass needle held with the needle pivot
designated as Z
axis parallel to the earth’s surface. Since a compass
needle always aligns itself parallel to the lines of force 2. The horizontal permanent field component,
of a magnetic field, the dip needle indicates the angle of designated as H
the earth’s field to the horizontal by aligning itself with
The horizontal permanent field component includes
the lines of force entering or leaving the earth at that
the longitudinal permanent field component and the
point. Both direction and strength of the field maybe
athwartship permanent field component. The vertical,
determined by a mine search coil and flux-measuring
longitudinal, and athwartship permanent field
equipment.
components are constant, except for slow changes with
Table 10-1 shows horizontal and vertical time. They are not affected by continuous changes in
component magnitudes and the resulting total field heading or magnetic latitude.

10-2
10-3
 All ships that are to be fitted with a shipboard the ship is south of the magnetic equator. Hence, the
degaussing installation and some ships that do not vertical induced magnetic field changes with magnetic
require degaussing installations, are depermed. latitude and to some extent, when the ship rolls or
Deperming is essentially a large-scale version of pitches. The vertical induced magnetic field does not
demagnetizing a watch. The purpose is to reduce change with heading because a change of heading does
permanent magnetization and bring all ships of the same not change the orientation of the ship with respect to the
class into a standard condition so the permanent vertical component of the earth’s magnetic field.
magnetization, which remains after deperming, is about
The longitudinal induced magnetic field changes
the same.
when either the magnetic latitude or the heading changes
and when the ship pitches. If a ship is heading in a
INDUCED MAGNETIZATION northerly geographical direction, the horizontal
component of the earth’s magnetic field induces a north
After a ship is built, its existence in the earth’s pole in the bow and a south pole in the stem (fig. 10-2,
magnetic field causes a certain amount of magnetism to view A). In other words, the horizontal component of
be induced into it. The ship’s induced magnetization the earth’s field induces a longitudinal or fore-and aft
depends on the strength of the earth’s magnetic field and
component of magnetization. The stronger the
on the heading of the ship with respect to the inducing
horizontal component of the earth’s magnetic field, the
(earth’s) field.
greater the longitudinal component of magnetization. If
Like the ship’s permanent magnetization, the ship’s the ship starts at the south magnetic pole and steams
induced magnetization is the source of the ship’s toward the north magnetic pole, the magnitude of the
magnetic field. This induced magnetic field can be longitudinal component of induced magnetization starts
resolved into the following components: at zero at the south magnetic pole, increases to a
maximum at the magnetic equator, and decreases to zero
1. The vertical induced field component.
at the north magnetic pole. Hence, for a constant
2. The horizontal induced field component. The heading, the longitudinal component of induced
horizontal induced field component also magnetization changes magnitude as the ship moves to
includes the longitudinal induced field a different latitude.
component and the athwartship induced field
If, at a given magnetic latitude, the ship changes
component.
heading from north to east, the longitudinal component
The magnitude of the vertical induced of the induced magnetic field changes from a maximum
magnetization depends on the magnetic latitude. The on the north heading to zero on the east heading. When
vertical induced magnetic field is maximum at the the ship changes heading from east to south, the
magnetic poles and zero at the magnetic equator. The longitudinal component increases from zero on the east
vertical induced magnetization is directed down when heading to a maximum on the south heading. On
the ship is north of the magnetic equator and up when southerly headings, a north pole is induced at the stem

Figure 10-2.—Effect of the earth’s magnetic field upon a ship.

10-4
and a south pole at the bow. This is a reversal of the an irregular permanent vertical magnetization, the ship
conditions on northerly headings, when a north pole is is scheduled to report for deperming.
induced at the bow and a south pole at the stern. The
longitudinal component of induced magnetic field also FREQUENCY OF RANGING
changes, to some extent, as the ship pitches.
The athwartship induced magnetic field changes All minesweepers and landing craft utilities (LCUs)
when either the magnetic latitude or the heading changes are required to be checked quarterly by a degaussing
and when the ship rolls or pitches. When a ship is on an range. All other ships that have a degaussing installation
east heading, a north pole is induced on the port side and must be checked semiannually. Submarines must be
a south pole on the starboard side (fig. 10-2, view B), checked annually. Any ship that exceeds check range
which is the athwartship component of induced limits must undergo calibration ranging or magnetic
magnetization. The magnitude of the athwartship treatment as soon as possible.
magnetic field depends on the magnitude of the
horizontal component of the earth’s magnetic field at
that latitude. The horizontal component is maximum at SHIPBOARD DEGAUSSING
the magnetic equator for a ship on an east-west heading, INSTALLATION
and zero at the magnetic poles or for a ship on a
north-south heading. A shipboard degaussing installation consists of the
following items:
MAGNETIC RANGING
One or more coils of electric cable in specific
locations inside the ship’s hull.
A ship is said to be ranged when its magnetic field
is measured at a magnetic range, commonly called a A means of controlling the magnitude and
degaussing range or degaussing station. A degaussing polarity of current to these coils and therefore the
range or station measures the magnetic field of ships that magnetic field produced by them.
pass over measuring equipment located at or near the
The ships degaussing folder.
bottom of the channel in which the ships travel.
A dc power source to energize these coils.
RANGING PROCEDURES
Compass-compensating equipment, consisting
of compensating coils and control boxes, to
Ships are ranged before they are depermed to compensate for the deviation effect of the
determine the direction and magnitude of their fields. degaussing coils on the ship’s magnetic
Magnetometer garden measurements also are required compasses.
during and after the deperming process to evaluate the
quality and effectiveness of the treatment. The most Used properly, these items will greatly reduce the
common ranging procedure, called check ranging, uses magnetic signature of the ship and help to prevent
the coil range. Check ranging usually occurs during a detection by magnetic sensitive instruments.
ship’s normal entry into port. After passing over the
range, the ship receives a report of its magnetic DEGAUSSING COILS
characteristics. If the strength of its magnetic field
exceeds a safe operational level, the ship is scheduled to
The distortion of the earth’s field caused by the
report for calibration ranging. Here the ship makes a
ship’s permanent magnetic field (vertical, longitudinal,
number of passes over the range while its shipboard
and athwartship components) and the ship’s induced
degaussing coils are adjusted and calibrated from
magnetic field (vertical, longitudinal, and athwartship
information supplied from the range hut. When the new
components) is neutralized by degaussing coils. The
settings for the degaussing coils have been determined,
degaussing coils are made with either single-conductor
new degaussing control settings are placed in the
or multiconductor cables. The coils must be energized
degaussing folder.
by direct current. This current is supplied from 120-volt
If the ship is unable to compensate adequately for or 240-volt dc ship’s service generators or from
its magnetic field because of excessive permanent degaussing power supply equipment installed for the
longitudinal or permanent athwartship magnetization or specific purpose of energizing the degaussing coils.

10-5
 Figure 10-5.—M coil.

to the components of the ship’s field. Each coil consists

of the main loop and may have smaller loops within the
area covered by the main loop, usually at the same level.
The smaller loops oppose localized peaks that occur in
the ship’s magnetic field within the area covered by the
main loop.

M Coil

Figure 10-3.—Magnetic field around a current-carrying The M (main) coil (fig. 10-5) encircles the ship in a
conductor.
horizontal plane, usually near the waterline. The M coil
produces a magnetic field that counteracts the magnetic
Coil Function field produced by the vetical permanent and vertical
induced magnetization of the ship.
Each of the components of the ship’s magnetization
(horizontal, vertical, and athwartships) produces a Figure 10-6 shows the magnetic field produced by
magnetic field in the vicinity of the ship. Current the vertical magnetization of the ship. Figure 10-7
through a conductor produces a magnetic field around shows the magnetic field produced by the M coil. The
it (fig. 10-3). By forming the conductor into a coil, a M-coil field opposes the magnetic field produced by the
magnetic field can be produced to surround the ship in vertical magnetization of the ship. If the M-coil
specific areas (fig. 10-4). Strategically locating these compensating magnetic field were everywhere exactly
coils and precisely controlling the magnitude and equal and opposite to the field produced by the vertical
polarity of the current through these coils will
effectively restore the earth’s field to the undistorted
condition around the ship.
Each degaussing coil has the required location and
the number of turns to establish the required magnetic
field strength when it is energized by direct current of
the proper value and polarity. The coils will then
produce magnetic field components equal and opposite

Figure 10-6.—Magnetic field due to the vertical magnetization

of the ship.

Figure 10-4.—Magnetic field of a current-carrying coil. Figure 10-7.—Magnetic field produced by the M coil.

10-6
 Figure 10-8.—F and Q coils.

magnetization, the result of the two magnetic fields F1-Q1 and FP-QP Coils
would be equal to zero. This is not possible to attain,
and as a result, the M-coil field is always considerably In many installations the conductors of the F and Q
less than the vertical field. The vertical permanent coils are connected to form two separate circuits
magnetization of a ship is constant while the vertical designated as the F1-Q1 coil and the FP-QP coil. The
induced magnetization varies with magnetic latitude, F1-Q1 coil consists of a F1 coil connected in series with
the Q1 coil so the current is the same in both coils. The
roll, and pitch, but not with heading. Consequently, the
same is true for the FP-QP coils in that they are also
M-coil field strength must be changed when the ship
connected in series and the same current is in both coils.
changes magnetic latitude to keep the M-coil field as Installations with both F1-Q1 and FP-QP coils are known
nearly equal and opposite to the field produced by the as split-coil installations because the F and Q coils are
ship’s vertical magnetization. split into two coils.

The F1-Q1 coil is used to counteract the magnetic

F and Q Coils
field produced by the ship’s longitudinal induced
magnetization. The coil field strength depends on two
The F (forecastle) coil encircles the forward factors—the ship’s heading and the magnetic latitude.
one-fourth to one-third of the ship and is usually just As the ship’s heading and magnetic latitude change, the
below the forecastle or other uppermost deck. The Q ship’s longitudinal induced magnetization changes
(quarterdeck) coil encircles the after one-fourth to accordingly.
one-third of the ship and is usually just below the The FP-QP coil is used primarily to counteract the
quarterdeck or other uppermost deck, as shown in figure magnetic field produced by the ship’s longitudinal
10-8. permanent magnetization, and it is sometimes used to
provide some compensation to supplement the M coil
The F and Q coils counteract the magnetic field
produced by the ship’s longitudinal permanent and
induced magnetization. The shape of the magnetic field
produced by the ship’s longitudinal permanent and
longitudinal induced magnetization and the two fields
are directed below the bow and stem of the ship. Look
at figure 10-9. Here, you can see that the ship’s
longitudinal permanent magnetization is constant, but
the longitudinal induced magnetization changes with
heading and magnetic latitude. The F- and Q-coil field
strengths must both be changed whenever the ship
changes course or magnetic latitude. These field
strengths must also be changed if the coil field strengths
would not have the proper values to counteract the
changed longitudinal induced magnetization. Note that
both adjustments must be made, one for the F-coil field Figure 10-9.—Longitudinal field of ship and neutralizing
strength and one for the Q-coil field strength. fields of F and Q coils.

10-7
 Figure 10-10.—L coil.

for vertical induced magnetization. However, if the MANUAL CURRENT CONTROL

FP-QP coil is used to provide vertical induced
compensation, its coil field strength must be changed Many of the older (prior to the mid-1950s)
when the ship’s magnetic latitude changes. three-coil degaussing installations and all installations
with only an M coil have operator current control.
These installations were fabricated and installed by the
L Coil
shipbuilders. They were never assigned type
designations. Manual or operator control is necessary
The L (longitudinal) coil (fig. 10-10) consists of because an operator must adjust the degaussing coil
loops in vertical planes parallel to the frames of the ship. currents when they have to be changed due to a change
The L coil is always used when compensation for the in the ship’s heading or magnetic latitude or both. In
pitch of the ship is required. The function of the L coil such installations, roll and pitch compensation is not
is to counteract the magnetic field produced by the ship’s provided.
longitudinal permanent and induced magnetization.
The equipment controls power obtained from
The L coil is more difficult to install than the F and Q
constant voltage dc generators in some installations and
coils or FI-QI and FP-QP coils; however, it provides
from degaussing motor generators in other installations.
better neutralization because it more closely simulates
Coil currents are set by adjustment of the rheostats. The
the longitudinal magnetization of the ship. The L coil is
rheostats cnfigured in series with the degaussing coils
commonly used in minesweeper vessels.
when power is obtained from a constant voltage source
and in series with the generator field when
The longitudinal induced magnetization changes
motor-generators are used for power source. Both
when the ship changes heading or magnetic latitude, and
manually operated and motor-driven rheostats are used.
the L-coil current must be changed accordingly.
For each of the ship’s degaussing coils, the required coil
currents, the various magnetic latitudes, and major
A Coil ship’s headings are obtained from the degaussing charts
in the ship’s degaussing folder. These current values are
determined for one latitude and calculated for other
The A (athwartship) coil (fig. 10-11) has loops in the latitudes during calibration ranging. The current values
vertical fore-and-aft planes. The function of the A coil given in the degaussing folder for the various zones of
is to produce a magnetic field that will counteract the operation represent the sum of the induced field and
magnetic field caused by the athwartship permanent and perm field currents.
athwartship induced magnetization. Since the
athwartship induced magnetization changes when the AUTOMATIC CURRENT CONTROL
ship changes heading, magnetic latitude, or rolls, the
A-coil strength must be changed accordingly.
Automatic degaussing (AUTODEG) control
equipment adjusts some or all of the coil currents
automatically with changes in ship’s attitude (heading,
roll, pitch, trim, and list) or with changes in both attitude
and location. AUTODEG control equipment is installed
on all ships with degaussing coils installed in more
than one place. Currently, the two basic types of
Figure 10-11.—A coil. AUTODEG control equipment currently are

10-8
(1) magnetometer-controlled equipment and (2) for the change in induced magnetization caused by a
gyro-controlled equipment. change in ship’s heading.

Magnetometer Control
Emergency Manual Control

Signals to control the induced field currents are

obtained from a three-axis magnetometer. The All AUTODEG control equipment is equipped with
magnetometer measures the components of the earth’s emergency manual control for use if the automatic
field along the axis of the ship and automatically adjusts controls become inoperative. This equipment is
the coil currents in a manner that will compensate for manually operated by the operator. The operator sets
changes in induced magnetization caused by the ship’s currents to values obtained from the ship’s degaussing
roll and pitch and by changes in the ship’s heading and folder for the various magnetic latitudes and adjusts the
geographical location. You can obtain the perm field eight-course heading switch as the ship’s heading varies.
current by biasing the magnetometer output with a perm
bias component or by providing a P coil with a separate
regulated current source or a combination of both
TYPES OF AUTOMATIC DEGAUSSING
methods.
SYSTEMS
Magnetometer control is used on nonmagnetic
minesweepers because roll and pitch compensation and Look at table 10-2, which contains brief
smooth or stepless zone control (magnetic latitude descriptions of the different types of AUTODEG. For
variations) are needed for these ships. It is also used on detailed descriptions, you should refer to the applicable
minesweepers because the magnetometer can be readily technical manuals. The first three types of equipment
located so it measures the earth’s field rather than a shown in the table are the only types being installed on
combination of earth’s field, ship’s field, and other new ships.
interference fields.

Magnetometer control is used on some steel-hulled MDG DEGAUSSING EQUIPMENT

ships with aluminum superstructures, where the effect
of the ship’s field on the magnetometer can be cancelled
MDG degaussing equipment is installed on
by compensation techniques. Magnetometer control is
nonmagnetic minesweepers. This equipment consists
used on these ships to eliminate operator inputs (H, Z,
of a fluxgate-type triaxial magnetometer probe installed
and magnetic variation) required with gyro-controlled
on the ship’s mast and a control unit containing all
equipment.
control and power circuits installed in the combat
information center (CIC) or the pilothouse (fig. 10-12).
Gyro Control The magnetometer probe is located and aligned so it
measures the local earth’s magnetic field components
Signals to control the induced field currents are along each of the ship’s three axes. These field
obtained from the ship’s gyrocompass and gyro components are biased and amplified by the degaussing
stabilizer systems. These signals are modified by equipment to produce required degaussing coil currents
operator inputs for magnetic latitude and heading (fig. 10-13). The probe’s location must be free of
(operator sets H, Z, and magnetic variation controls). interference produced by the ship’s magnetic field,
They are processed by an analog computer to provide degaussing coils, and other installed equipment. The
induced field currents proportional to the calculated equipment is unique in that 90 separate power amplifiers
values of the earth’s magnetic field component along the are available to supply the ship’s degaussing loops.
ship’s axis.

You can obtain the perm field current by biasing

Magnetometer-controlled AUTODEG
computer output or with a separate P coil or a
Equipment Operation
combination of both methods. Gyro control is presently
used on ships that do not require roll and pitch
compensation. On these ships, the control signal is Two modes of operation are used for magnetometer
obtained from the ship’s gyrocompass, and the coil controlled AUTODEG equipment—automatic and
currents are adjusted automatically to compensate only manual.

10-9
Table 10-2.–Description of Different Automatic Degaussing Equipment

10-10
Figure 10-12.—Type MDG automatic degaussing equipment.

10-11
 Figure 10-13.—Block diagram for type MDG degaussing system.

AUTOMATIC OPERATION.— When setup for During calibration of the degaussing system at a
automatic operation, magnetometer-controlled degaussing range, the number of coil turns, the current
AUTODEG equipment will control the currents in the magnitude, and the polarities are established. When
ship’s degaussing coils to compensate for the ship’s calibration is completed, the coils are adjusted for the
permanent and induced magnetism, regardless of the proper number of turns, the equipment is adjusted for
ship’s heading, roll, pitch, or geographic location. automatic operation, and all pertinent information is
Automatic operation is the normal mode and consists recorded in the ship’s degaussing folder. During normal
primarily of turning equipment on and periodically (automatic) operation, none of the controls are adjusted
monitoring the front panel indicators and current or reset. You should monitor the trouble indicators
outputs for indications of equipment malfunction. periodically, checking the current outputs as follows:

10-12
 MANUAL OPERATION.— Magnetometer- approximate optimum inputs and since no roll or pitch
controlled equipment provides for operator control of inputs are provided, compensation of the ship’s induced
degaussing coil currents when a fault exists in the magnetism using manual operation is not as good as the
magnetometer group circuits. Adjustments associated compensation obtained with automatic operation. For
with the ship’s heading and the local earth’s field (Hand this reason, when normal operation is not possible, you
Z zone of operation) are made during manual operation. should manually operate only the affected coil or coils.
Since operator-set heading and earth’s field inputs only The general procedure for manual operation is as follows:

10-13
 The exact procedures vary with the equipment
installed. Some equipment has separate manual
current controls that should be preset so that they do not
have to be adjusted when the coils are switched to
manual operation. On equipment with common current
controls for automatic and manual operation before
switching to manual operation, adjust the control to zero
current (maximum CCW). When you adjust the current
on the operating equipment, consult the technical
manual furnished with the equipment for detailed
information.

Gyro-controlled AUTODEG Equipment

Operation

Like magnetometer-controlled equipment,

gyro-controlled AUTODEG equipment has two modes
of operation-automatic and manual.

AUTOMATIC OPERATION.— When set up

for automatic operation, gyro-controlled equipment
will automatically make changes in coil currents
that are required because of changes in the ship’s
heading. Gyro-controlled equipment will not
automatically make changes in coil currents that with the values specified in the degaussing folder for the
are necessary when the ship changes its magnetic ship’s location. Magnitude and polarity of A- and FI-QI
latitude. coil currents will vary with the ship’s heading. Monitor
these on cardinal headings or calculate them. Ensure
NOTE: Older equipment once automatically
that the FI-QI current is equal to the value specified for
changed coil currents to provide for compensation
the ship’s location multiplied by the cosine of the ship’s
of the ship’s roll and pitch. This type of
magnetic heading angle and that the A-coil current is
equipment is now obsolete and has been
equal to the value specified for the location times the
converted to magnetometer control or removed from
sine of the magnetic heading angle.
service.

Automatic operation is the normal mode of MANUAL OPERATION.— Gyro-controlled

operation and consists primarily of energizing equipment has a provision for operator control of the A-
the equipment, periodic monitoring for indications and FI-QI coil currents if there is a loss of the gyro signal
of malfunction, and adjusting current controls as a or a fault in the control computer. Manual operation
ship moves from one H and Z zone to consists of the heading switch set for the ship’s magnetic
another. Gyro-controlled equipment, like heading and the H-zone switch set for the ship’s
magnetometer-controlled equipment, is completely position. Since step inputs from the heading switch only
set up and adjusted when the ship’s degaussing approximate heading signals from the gyro and control
system is initially calibrated at the range. However, computer, the ship’s induced magnetism compensation
some controls on this equipment must be set during manual operation is not as good as that provided
each time the equipment is energized. The by automatic operation. Consequently, manual
general procedure for automatic operation is as operation should be used only when normal operation
follows: is not possible.

10-14
 The operator should set up the equipment for TYPE SSM
manual operation (the manual-induced magnitude
current controls should be adjusted and locked) at the SSM degaussing equipment is the standard
same time it is set up for automatic operation. This will degaussing equipment installed on all ships that require
degaussing, except nonmagnetic minesweepers and
enable the operator to switch from automatic to manual
patrol frigates (FFG-7 class). This equipment has a
operation without having to adjust current magnitude.
control switchboard, a remote control unit, and a power
Incorrect current magnitudes and polarities can be supply for each installed degaussing coil (fig. 10-14).
dangerous in a mine danger area. The general procedure The switchboard contains operator controls, control
for manual operation of the FI-QI or A coil is as follows: circuits, and status indicators for all coils. The remote
control unit provides status indicators and a heading
switch for emergency manual operation in a remote
location (usually the pilot house). The power supplies
amplify control signals from the switchboard.
The switchboard is functionally divided to
operation and maintenance easier. The computer
drawer contains a mechanical computer and the controls
necessary to provide induced A- and FI-QI coil current
magnitudes for the ship’s heading and location (fig.
10-15). The automatic and manual drawers contain
current controls, meters, and status indicators for the
automatic coils (A and FI-QI) and the manual coils (M
and FP-QP). The ground detector, temperature alarm
bell, power-supply blown-fuse indicators, and power
switches are located on the front panels.
The power supplies (fig. 10-16) are supplied in
standard power ratings, and they differ only in output
current ratings. AU are functionally identical.

TYPE MCD

MCD degaussing equipment is installed on FFG-7

class ships. This equipment consists of a fluxgate-type
triaxial magnetometer, a control unit, a remote control
unit, and a power supply unit for each installed
degaussing coil. It is essentially a combination of EMS
equipment and SSM equipment. The magnetometer
and control unit are functionally similar to the EMS
magnetometer and control unit. The main differences
are that additional compensation features are provided
to minimize the effect of the ship’s magnetic field at the
magnetometer and that the control unit outputs are
current signals to the power supplies instead of currents
to the degaussing coils. The remote control unit and the
power supplies are similar to the SSM remote control
unit and power supplies.

MARKING SYSTEM

For ease of maintenance by the ship’s force, the

degaussing installations in all types of naval vessels are
marked following a standard marking system. All

10-15
 Figure 10-14.—SSM automatic degaussing equipment.

feeders, mains, and other cables supplying power to marking is parallel to the axis of the conductor. Table
degaussing switchboards, power supplies, and control 10-3 shows the letters used for cable designations and
panels are designated and marked as specified for power cable tag markings for degaussing coil cables and
and lighting circuits. The system of markings and circuits.
designations of conductors applies specifically for a For a detailed description of the marking for
multiconductor system, but it is also applicable to degaussing-coil imps, circuits, conductors, and cables,
single-conductor installations. and for degaussing feeder cable and feeder cable
Degaussing cable identification tags are made of conductors, refer to chapter 475 of the Naval Ships’
metal. The cables are tagged as close as practicable to Technical Manual.
both sides of decks, bulkheads, or other barriers.
Degaussing conductors are marked by hot stamping
(branding) insulating sleeving of appropriate size. Each CONNECTION AND THROUGH
BOXES
end of all conductors are marked, and the conductor
marking corresponds to the marking of the terminal to Connection and through boxes are similarly
which they connect inside the connection box or through constructed watertight boxes, but they are used for
box. The sleeving is pushed over the conductor so the different purposes.

10-16
 Figure 10-15.—Block diagram for an SSM degaussing switchboard.

A connection box is a watertight box with a interconnecting cable for the FI-QI and FP-QP coils
removable cover used to connect loops together, to terminate in connection boxes.
connect conductors in series, and to reverse turns. The
A through box is a watertight box with a removable
power supply connection for a coil and all adjustments
of ampere-turn ratios between loops are made within cover used to connect conductors without a change in
connection boxes. The power supply cable and the order of conductor connections. Also, a through box

Figure 10-16.—Block diagram for a type SSM degaussing power supply.

10-17
Table 10-3.—Degaussing Installation Markings

10-18
is used to connect sections of cable. In some cases, 10-18) with the value of coil settings, installation
splicing is used instead of through boxes. information, and a log section showing the details of
the action taken on the ship’s degaussing system.
A wire diagram of the connections in the box is
pasted on the inside of the cover and coated with varnish The folder is prepared by degaussing range
or shellac. The wiring diagram for connection boxes personnel when the ship’s degaussing system is initially
should (1) designate the conductors that may be calibrated.
reversed without reversing the other loops, (2) indicate
the arrangement of parallel circuits so equal changes can
PREVENTIVE MAINTENANCE
be made in all parallel circuits when such changes are
required, and (3) show the spare conductors. Spare Preventive maintenance is extensive for automatic
conductors should be secured to connection terminals in degaussing systems. The degaussing switchboards and
the connection boxes and should not form a closed or remote panels require frequent cleaning and inspection
continuous circuit. All conductors in a connection box as they are sensitive to heat and dirt. The removal of
should be 1 1/2 times the length required to reach the dirt and dust from automatic degaussing control
farthest terminal within the box. Connection boxes equipment allows the natural flow of air around the
should also have drain plugs accessible to provide for components for heat dissipation. Use of a vacuum
periodic removal of accumulated moisture from the cleaner or bellows is a safe way to remove dust or dirt.
boxes. Do not use compressed air.
Connection and through boxes have Check the connection or through boxes for
IDENTIFICATION PLATES that include degaussing moisture. Drain plugs are installed in the bottom of
box numbers (such as D1 and D2), connection box connection or through boxes to help you accomplish
and/or through boxes as applicable, and coil and loop your inspection. When you notice moisture in a box
designations (such as Ml, M2, and F12). during your inspection, leave it open to dry out. At the
same time, check the box cover gasket for deterioration,
and replace it if necessary.

When performing any preventive or corrective

maintenance on AUTODEG, observe standard
electrical safety precautions.
For additional information on degaussing systems,
refer to the Naval Ships’ Technical Manual, chapters
300 and 475, and the manufacturers’ instruction books.
This sample identified the No. 1 degaussing box serving
as a connection box for the M1 and M2 loops and as a
SUMMARY
through box for the F1 loop.
In this chapter, we have discussed the degaussing
systems installed aboard ships of the Navy. After
DEGAUSSING FOLDER
studying the information, you should have a better
The degaussing folder is an official ship’s log. It understanding of the earth’s magnetic field, ship’s
contains information on the magnetic treatment of the magnetic fields, degaussing coils, ranging procedures,
ship, instructions for operating the shipboard operation of various types of systems, and cable
degaussing system, degaussing charts (figs. 10-17 and markings for degaussing installations.

10-19
10-20
10-21
 CHAPTER 11

CATHODIC PROTECTION

This chapter contains a discussion about the Agueous— Pertaining to water; for example, an aqueous
cathodic protection systems installed in naval ships. solution is a water solution.
there are two systems—the sacrificial anode system
Base— A solution that contains an excess of hydroxyl
and the impressed current system. The two systems are
ions and exhibits a pH above the neutral value of 7.
different in both construction and operation.
Cathode— The electrode of an electrochemical cell at
which reduction is the principal reaction. The
LEARNING OBJECTIVES electrode where corrosion usually does not occur
Upon completion of this chapter, you will be able to unless the electrode metal is amphoteric.
do the following: Cathodic corrosion— Corrosion of a metal when it is a
1. Recognize the purose of cathodic protection. cathode. Cathodic corrosion occurs on metals, such
as Al, Zn, Pb, when water solution turns strongly
2. Identify the two major types of cathodic alkaline as a result of the normal cathodic reactions.
protection available. It is a secondary reaction between the alkali
3. Identify the major components of both types of generated and the amphoteric metal.
cathodic protection systems. Cathodic polarization— The change of the electrode
4. Define various terns used to descibe cathodic potential in the negative direction due to current
protection components and processes. flow.
Cathodic protection— A technique or system used to
reduce or eliminate the corrosion of a metal by
TERMS
making it the cathode of an electrochemical cell by
Several terms used with this chapter may be means of an impressed direct current or attachment
unfamiliar to you. Because you’ll need to understand of sacrificial anodes, such as zinc, magnesium, or
them, they are defined at this point in the chapter. aluminum.

Acid— A solution that contains an excess of hydrogen Cell— A circuit or system consisting of an anode and a
ions and exhibits a pH below the neutral value of 7. cathode in electrical contact in a solid metal or liquid
conducting environment.
Active— A state in which a metal tends to corrode
(opposite to passive); freely corroding. Corrosion— The reaction between a material and its
environment that results in the loss of the material
Amphoteric metal— A metal capable of reacting or its properties. For example: when used as a
chemically either as an acid or as abase. material of construction, the transformation of a
Anode— The electrode of an electrochemical cell circuit metal from the metallic to the nonmetallic state.
where corrosion occurs, and metal ions enter the Corrosion potential— The potential that a corroding
solution. metal exhibits under specific conditions of
Anodic polarization— The change of the electrode concentration, time, temperature, or velocity in an
potential in the noble (positive) direction due to electrolytic solution and measured relative to a
current flow. reference electrode under open-circuit conditions.
Corrosion product— A product resulting from
Antifouling— The prevention of marine organism
corrosion. The term applies to solid compounds,
attachment or growth on a submerged metal surface
gasses, or ions resulting from a corrosion reaction.
through chemical toxicity. Achieved by the
chemical composition of the metal, including toxins Corrosion rate— The speed at which corrosion
in the coating or by some other means of distributing progresses. Frequently expressed as a constant loss
the toxin at the areas to be kept free of fouling. or penetration per unit of time. Common units used

11-1
 are mils per year (mpy), millimeters per year (Should not be used to mean corrosion by stray
(mm/y), and micrometers per year (µm/y). 1 mil= currents.)
0.001 inch 1 mm= 0.001 meter, 1 µm = 0.000001 Electrolyte— A substance that, in solution, gives rise to
meter. ions; an ionic conductor usually in aqueous
Current capacity— The hours of current that can be solution a chemical substance which on dissolving
obtained from a unit weight of a galvanic anode in water renders the water conductive.
metal. Usually expressed in ampere hours per
Electrolytic cell— A system in which an anode and
pound (amp-hr/lb) or ampere hours per kilogram
cathode are immersed in an electrolytic solution and
(amp-h/kg).
electrical energy is used to bring about electrode
Current density— The current per unit area of surface of reactions. The electrical energy is thus converted
an electrode. Commonly used units include the into chemical energy. (NOTE: The term
following: electrochemical cell is frequently used to describe
both the electrochemical cell and the electrolytic
cell.)

Electrolytic solution— A solution that conducts electric

current by the movement of ions.

Electromotive force (emf) series— A list of elements

arranged according to their standard electrode
potentials (the hydrogen electrode is a reference
point and is given the value of zero), with noble
metals, such as gold being positive, and active
metals, such as zinc, being negative.

Embrittlement— Severe loss of ductility of a metal or an

alloy.
Current efficiency— The ratio of the actual total current External circuit— Wires, connectors, measuring
measured from a galvanic anode in a given time devices, current sources, and so forth, that are used
period to the total current calculated from the weight to bring about or measure the desired electrical
loss of the anode and the electrochemical equivalent conditions within the test cell. In corrosion
of the anode metal is expressed as a percentage. terminology it also includes that part of an
Eletrochemical cell— A system consisting of an anode electrochemical cell external to the solution
and a cathode immersed in an electrolytic solution.
Galvanic corrosion— Corrosion of a metal because of
The anode and cathode may be different metals or
electrical contact with a more noble metal or
dissimilar areas on the same metal surface. A cell
nonmetallic conductor in a corrosive environment.
in which chemical energy is converted into
Often used to refer specifically to bimetallic
electrical energy under the condition of current flow
corrosion; sometimes called couple action.
between anode and cathode.
Electrode— A metal or nonmetallic conductor in contact Galvanic couple— Two or more dissimilar connductors,
with an electrolytic solution that serves as a site commonly metals, in electrical contact in the same
where an electric current enters the metal or electrolytic solution.
nonmetallic conductor or leaves the metal or Galvanic series— A list of metals and alloys arranged
nonmetallic conductor to enter the solution. according to their relative corrosion potentials in a
Electrode potential— The difference in electrical given environment. (NOTE: This series may not
potential between an electrode and the electrolytic be the same order as in the EMF series.)
solution with which it is in contact; measured Half-cell— One of the electrodes and its immediate
relative to a reference electrode. environment in an electrochemical cell; an
Electrolysis— The production of chemical changes in an electrode and environment arranged for the passage
electrolytic solution caused by the passage of of current to another electrode for the measurement
electrical current through an electrochemical cell. of its electrode potential; when coupled with

11-2
 another half-cell, an overall cell potential develops metal ion in solution goes to the metallic state at a
that is the sum of both half-cell potentials. cathode in an electrochemical cell.

Hydrogen blistering— The formation of blisterlike Reference electrode— A half-cell of reproducible

bulges on or below the surface of a ductile metal potential by means of which an unknown electrode
caused by excessive internal hydrogen pressure. potential can be determined on some arbitrary scale
Hydrogen may be formed during cleaning, plating, (for example, Ag/AgC1, SCE, Cu/CuSO4). A
corrosion, or cathodic protection. standard against which the potentials of other metal
and nonconductive conductor electrodes are
Hydrogen embrittlement— Severe loss of ductility
measured and compared.
caused by the presence of hydrogen in the metal; for
example, through pickling, cleaning, of cathodic Shield— A nonconducting coating, paint, or sheet that is
protection. used to beneficially change the current on a cathode
Ion— An electrically charged atom (such as Na+, C+) or anode; normally used with impressed current or
or group of atoms (such as NH4+, SO=, PO=). other high-potential cathodic protection systems to
distribute the current beyond the immediate vicinity
Noble— A state in which a metal tends not to be active; of the electrode.
the positive direction of electrode potential.
Stray-current corrosion— Corrosion caused by current
Noble metal— A metal that is not very reactive, such as
flow from a source (usually dc) through paths other
silver, gold, or platinum, and that may be found
than the intended circuit or by extraneous currents
naturally in metallic form on earth.
in the electrolytic solution.
Noble potential— Apotential toward the positive end of
a scale of electrode potentials.
Open-circuit potential— The potential of an electrode CATHODIC PROTECTION
measured with respect to a reference electrode when
Cathodic protection reduces the corrosion or
essentially no current flows to or from the electrode.
deterioration of metal caused by a reaction with its
Oxidation— Loss of electrons by a metal during a environment (ship’s hull and seawater). The chemical
chemical or electrochemical reaction; as when a action that is created is similar to the electrochemical
metal goes from the metallic state to the corroded action of a battery or cell. Figure 11-1 shows a dry-cell
state when acting as an anode; when a metal reacts battery circuit. The positive current is indicated by a
with oxygen sulfix, and so on to form a compound positive deflection of the voltmeter needle when the
such as oxide or sulfide. positive terminal of the meter is connected to the
pH— A logarithmic measure of the acidity or akalinity cathode (positive terminal) of the cell. As the
of a solution. A value of 7 is neutral; low numbers electrochemical action continues, the process will
are acid (1-6); large numbers are alkaline (8-14). eventually corrode or consume, the anode that is
Each unit represents a tenfold change in providing the current to light the lamp. This process is
concentration. called electrochemical action.

Polarization— The shift in electrode potential from the

open-circuit potential value resulting from the
effects of current flow.
Potential— A numerical value (measured in volts) for
an electrode in a solution and defined with reference
to another specified electrode.
Protective potential— A term used in cathodic
protection to define the minimum potential required
to mitigate or suppress corrosion. For steel in
quiescent seawater a value of -0.80 volt to Ag/AgC1
reference electrode is generally used.
Reduction— Gain of electrons by a metal during a
chemical or electrochemical reaction; as when a Figure 11-1.—Dry-cell battery circuit.

11-3
ELECTROCHEMICALACTION between two dissimilar metals. Generally, normal
seawater has a nominal resistivity of 20 to 22 Ohms/cm
In a marine environment, corrosion is an at a temperature of 20°C (68°F). In brackish or fresh
electrochemical process caused when two dissimilar water this resistivity may vary.
metals are immersed in seawater, with the seawater
acting as the electrolyte. This process is shown in the
TYPES OF CATHODIC
electrochemical corrosion cell (fig. 11-2). You must
PROTECTION
understand that in an electrochemical cell, a metal that
is more corrosion prone always has a higher driving There are two types of cathodic protection
voltage than the metal that is less corrosion prone. In systems—the sacrificial anode system and the
cathodic protection the more corrosion-prone metal is impressed current system. Each system will be
the anode (zinc, for example) and the less addressed separately.
corrosion-prone metal is the cathode (steel hull, for
example). The rate of corrosion is directly related to the SACRIFICIAL ANODE SYSTEM
magnitude of the potential difference and is referred to
as the open-or half-cell potential of metals. Some of the The sacrificial anode system is based on the
factors affecting the amount of corrosion are stray following principle:
currents, resistivity, and the temperature of the seawater.
When a more reactive metal is installed near a
Stray-current corrosion is caused by an external less reactive metal and submerged in an
current leaving the hull of a vessel and entering the electrolyte such as seawater, the more reactive
seawater. If the connection between the ship and metal will generate a potential of a sufficient
welding machine is not correctly made (fig. 11-3) or no magnitude to protect the less reactive metal.
return lead to the welder is connected, you could have
In this process, the more reactive metal is sacrificed.
current flow between the ship’s hull and the pier. This
Sacrificial anodes attached to a ship’s hull slowly
current flow causes corrosion to form on the hull.
oxidize and generate a current (see the electrochemical
Seawater resistivity is the concentration of ions in corrosion cell in figure 11-2 that protects the hull and its
seawater, which acts as a resistance to current flow appendages). The system shown in figure 11-2 does not

Figure 11-2.-Electrochemical corrosion cell.

11-4
have an onboard control of protecting current and MAGNESIUM ANODES.— Magnesium anodes
depends on the limited current output of the anode. This have a half-cell potential of about negative 1.5 volts.
type of system requires anode replacement on a fixed They aren’t used in seawater applications because of
schedule (usually every 3 years on naval ships). The rapid loss of the anode material and overprotection due
system is rugged and simple, requires little or no
to the high driving voltage. Magnesium anodes are used
maintenance, and always protects the ship.
in fresh or brackish water areas where the resistivity of
Types of Sacrificial Anodes the electrolyte is relatively high and a higher driving
voltage is required to produce the proper amount of
The sacrificial anodes listed below are discussed in polarizing current.
this section. IRON ANODES.— Iron anodes are installed to
1. zinc increase the presence of iron ions in the water. The
increase of iron ions strengthens the formation of the
2. Aluminum
oxide film produced on copper alloy surfaces.
3. Magnesium
STEEL WASTER PIECES.— Steel waster pieces
4. Iron
are sleeves of mild steel installed at nonferrous metal
5. Steel waster pieces junctions to protect sea valves and sea chests.
ZINC ANODES.— Zinc anodes are@ for anodic
polarization on steel or aluminum surfaces. They have
Uses of Sacrificial Anodes
a half-cell potential of a negative 1.04 volts. Zinc
anodes can be either bolted or welded to the hull.
Welding is the preferred method because the anodes will Sacrificial anodes are used in small boats,
have a secure electrical and mechanical attachment. mothballed ships, and submarines. They may be
ALUMINUM ANODES.— Aluminum anodes are installed in piping systems, bilge pumps, valves, ballast
currently being tested and evaluated by the Naval Sea tanks, fuel tanks, sewage collection holding tanks
Systems Command (NAVSEASYSCOM). (CHTs), sonar domes, voids, and stem tubes.

Figure 11-3.—Stray-current corrosion.

11-5
 Table 11-1.—Advantages and Disadvantages of Sacrificial Anodes

Advantages and Disadvantages of Sacrificial power provided by a regulated dc power supply to

Anodes provide the current necessary to polarize the hull. The
protective current is distributed by specially designed
Table 11-1 shows the advantages and disadvantages inert anodes of platinum-coated tantalum. The
of sacrificial anodes. principal advantage of an ICCP system is its automatic
control feature, which continuously monitors and
varies the current required for corrosion protection. If
IMPRESSED CURRENT CATHODIC
the system is secured, no corrosion protection is
PROTECTION SYSTEM
provided.

The impressed current cathodic protection (ICCP)

system (fig. 11-4) uses an external source of electrical

Figure 11-4.—Basic impressed current cathodic protection system.

11-6
Components of the ICCP System POWER SUPPLY.— The power supply performs
the following two functions:
The components of the ICCP system are listed 1. It converts available shipboard ac to low-voltage
below and discussed in this section. dc.
1. Power supply 2. It provides a means of adjusting the value of
current delivered to the anodes.
2. Controller
CONTROLLER.— The controller (fig. 11-5) is
3. Anodes
used to monitor the control power supply outputs that
4. Reference electrode maintain the hull at a preset potential versus the
5. Stuffing tube reference cdl. The controller is a sensitive amplifier
that creates an output signal proportional to the voltage
6. Shaft grounding assembly
difference between the reference (electrode-to-hull)
7. Rudder ground (including stabilizer if installed) voltage and the internally set voltage. The controller
8. Dielectic shield should be mounted in a readily accessible area.

Figure 11-5.—Magnetic amplifier controller Mod III.

11-7
Figure 11-6.—Anode assembly.

11-8
Table 11-2.—Anode Locations on the Underwater Hull ANODES.— The anodes (fig. 11-6) are constructed
of two platinum-mated tantalum rods mounted in an
insulating glass-reinforced polyester holder. Anodes
are bolted to the outside of the ship’s hull. The dc flows
into the seawater through the platinum surface of the
tantalum rods. The platinum surface of the anode
corrodes very slowly. The replacement period for
anodes is usually 10 years or longer. Anodes are
available in three sizes—2 feet (40 amperes), 4 feet (75
amperes), and 8 feet ( 150 amperes).
When installed (table 11-2), anodes should be
placed to maintain a uniform potential throughout the
underwater hull. The following is a list of anode
locations:

REFERENCE ELECTRODE.— The reference

electrode (fig. 11-7) is a silver/silver chloride type
constructed of a silver mesh screen that has been treated
with silver chloride. The reference electrode is bolted
to the exterior hull of the ship and is insulated from the
ship by a polyvinyl chloride holder. A stuffing tube is
used to pass the cable from the electrode through the hull
to the controller. The controller measures the potential
of the hull versus the reference electrode, and signals
the power supply to increase or decrease current output

Figure 11-7.—Reference electrode assembly.

11-9
as required. Varying the current output reduces the SHAFT GROUNDING ASSEMBLY.— The shaft
potential difference between the hull potential and the grounding assembly (fig. 11-8) consists of a silver-alloy
preset desired potential. Two reference electrodes are band, ring-fitted on the propeller shaft. The assembly
installed for each controller—One is selected for the is electrically bonded to the shaft and is usually located
primary control, and the other serves as an auxiliary to in the shaft alley. Silver-graphite brushes ride on the
hard silver surface of the bands, electrically connecting
verify operation of the controlling cell and seines as a
the rotating propeller shaft to the hull. This assembly is
backup if failure of the primary cell occurs. Reference
necessary to permit the anode current that flows through
electrodes are generally located on each side of the hull,
the water to enter the propeller blades and return to the
about halfway between the anode sites. Reference hull. A shaft grounding assembly is provided for each
electrodes are usually replaced approximate] y every 10 shaft. Ships of carrier size or larger are fitted with two
to 12 years. brush assemblies on the silver-alloy ring.
STUFFING TUBE.— Stufflng tubes are required RUDDER GROUND.— Rudders and Stabilizers
to insulate the electrical wires that pass through the hull are grounded by brazing a braided, tinned-copper
to anodes or reference electrodes. grounding strap at least 1 1/2 inches wide between the

Figure 11-8.—Shaft grounding assembly.

11-10
rudder stock and the hull. To permit full rotation of the major differences in environment the ship
rudder stock from port to starboard, a large loop is encounter—seawater and brackish or fresh water.
required in the ground strap.
HULL POTENTIAL SETTING OF SHIPS IN
DIELECTRIC SHIELD.— The dielectric shield SEAWATER.—The impressed current system is
prevents shorting of the anode current to the hull and designed to operate automatically and requires a
aids in wider current distribution. The dielectric shield minimum amount of maintenance. The operator
is applied as a thick coating around each anode. It normally sets the hull potential at -0.85 volt. When the
consists of a high-solids epoxy with a high-dielectric voltage between the hull and the reference electrode is
strength. more positive than the voltage set by the operator, the
output of the controller increases. This causes an
Operation
increase in the anode current output from the power
The requirements for operating the ICCP system on supply until the voltage between the hull and the
ships is provided in the manufacturer’s technical reference electrode approaches the set voltage. A
manual. The system should be operated at all times, voltage between the hull and the reference electrode that
with the following exceptions: is negative to the set voltage causes a decrease in
controller output, thereby decreasing the anode current
1. During diving operations
output.
2. During equipment repair
The optimum range of polarization or
3. During planned maintenance hull-to-reference electrode potential for a ship with an
4. During drydocking ordinary steel hull is from a -0.80 to a -0.90 volt to the
silver/silver chloride reference electrode. Increased
The system must be reactivated within 2 hours after anode current will result in hull potentials more negative
the activity is completed. Never energize the system if than the optimum amount. Increasing the negative
the ship is out of the water (drydocked). potential does not provide more protection. If exceeded,
Before the reference electrode is connected to the this will result in hydrogen generation at the hull
controller, you should check the voltage between the surface.
reference electrode and the steel hull. The voltage HULL POTENTIAL SETTING OF SHIPS
should be approximately 0.6 volts dc. The hull will be ENTERING BRACKISH OR FRESH WATER.— As
negative (–), and the reference electrode will be positive
a ship enters a port or bay that is riverfed, the resistivity
(+). If the voltage is zero, the reference electrode has
of the water will change as the salinity changes.
an open lead or the lead or electrode is shorted to the
Operation of the ICCP system will be affected by the
hull. When the voltage is 0.6 volts or higher, the ship is
changing water resistivity. The operator will notice the
receiving cathodic protection from an external source, ICCP system operating at higher voltage outputs and
which could be zinc anodes or an electrical leakage.
lower current outputs. The lower current output is
You need to inspect the controller and power supply caused by the higher impedance of the water. A higher
wiring to ensure the unit is properly grounded. Before voltage output is required to drive the same current in
connecting the anode leads to the power supply, check the higher-resistivity electrolyte. The operator will
for possible shorts. The voltage developed between a record this condition on the ICCP log. Do not take
disconnected platinum anode and the steel hull will action to correct this condition by equipment calibration
range from 1.0 to 2.0 volts dc and can be read on a while the ship is in brackish water.
high-impedance voltmeter. The polarity of the anode is
Cathodic Protection Log
positive (+) and the polarity of the hull is negative (-).
If this voltage is zero, you could have an open lead wire Normal operating procedures require maintaining a
or a shorted anode. When the voltage reads between 2.0 Cathodic Protection Log, NAVSEA Form 9633/1 (fig.
to 5.0 volts, it indicates that the anode lead is immersed 11-9A and 11-9B) on ICCP system operation. The
in seawater. readings are recorded on these logs daily and submitted
to NAVSEA monthly. Logs submitted to NAVSEA are
Hull Potential Settings
analyzed to identify those systems that are not operating
As the ship’s water environment changes, so must correctly. After analysis of the logs is complete, a
the level of protection from the cathodic protection response is sent to the ship or TYCOM indicating the
system. The following paragraphs address the two operational status of the equipment as interpreted from

11-11
Figure 11-9A.—Cathodic Protection Log (front).

11-12
Figure 11-9B.—Cathodic Protection Log (back).

11-13
the logs. This response will recommend corrective take daily meter readings on the panel and record them
actions to be taken, if required. on the log. A quarterly check must be performed on the
OUTPUT CHECK.— A particularly significant shaft grounding assembly. A 24-month intervals, the
value recorded on the log is the output check. The panel meters are calibrated according to PMS
values recorded will range from practically zero to 1.0 requirements.
volt, representing 100 percent current output. If the
values range between 0.3 and 0.5 volt, the system is
operating at 30 to 50 percent capacity. SUMMARY

POWER SUPPLY.— The daily current output is In this chapter, you were introduced to the
recorded for each power supply. Ampere values may fundamentals of cathodic protection systems, including
vary, depending on the power supply, maximum output, their operation, logs, and maintenance. An
and current demand. Two capacities of power supplies understanding of these systems will enable you to
are used-0 to 150 amperes and 0 to 300 amperes.
ensure that the ship’s hull is maintained in a
noncorrosive condition at all times. Additional
ICCP Maintenance
information can be found in the manufacturer’s
The ICCP maintenance is performed according to technical manuals or Naval Ships’ Technical Manual,
the Planned Maintenance System (PMS). You should chapter 633, “Cathodic Protection. ”

11-14
 CHAPTER 12

VISUAL LANDING AIDS

This chapter contains an introduction to the 6. Various other lighting systems to aid the pilot in
function, identity, and operation of the visual landing aid operating under the more demanding
lighting equipment used aboard non-aviation ships for environmental conditions on ACS ships.
the operation and support of helicopters. The ability of
a ship to safely support helicopter operations greatly All components of the VLA (fig. 12-1) assist both
increases its effectiveness in ASW operations, its the helicopter and the ship in completing the assigned
supply/support functions, and makes emergent y mission.
transfer of personnel due to sickness much quicker.

LEARNING OBJECTIVES STABILIZED GLIDE SLOPE

Upon completion of this chapter, you will be able to INDICATOR SYSTEM
do the following: The stabilized Glide Slope Indicator (GSI) System
1. Identify the need for visual landing aids aboard is an electrohydraulic optical landing aid designed for
ship. use on ships equipped for helicopter operations. By use
2. Describe the operation of the stabilized of the stabilized GSI, a helicopter pilot may visually
platform assembly. establish and maintain the proper glide slope for a safe
3. Describe the function of the gyroscope input to landing.
the stabilized platform assembly. The GSI is mounted on a stable platform and
4. Identify the various components of the visual provides a tricolor (red, green, and amber) display of
landing aids. which one color (or mixing at the interface) is seen (fig.
Visual landing aids (VLA), consisting of helicopter 12-2). The color of the light bar indicates to the pilot
deck area marking, lighting, and approach aids, are whether the aircraft is above (green), below (red), or on
required on all air capable ships (ACS) to provide an (red/amber interface) the correct glide slope. In order
environment for safe helicopter operations. Deck to steady the GSI with respect to the pitching and rolling
markings identify the limits of the helicopter operating
motions of the ship, the light cell is mounted on an
area, provide line-up information, and identify the safe
electrohydraulic stabilization platform. The system
landing zone. Because of increasing demands for
all-weather and night operations, special lighting incorporates a failure detection circuit which turns off
systems have been designed to provide the helicopter the light in the event of stabilization failure.
pilot with the following data:
The Mk 1 Mod 0 stabilized GSI system has the
1. An initial visual contact with the ship following six major components (fig. 12-3):
2. A safe glide path to the landing area
1. Electronic enclosure assembly
3. Precise information (visual cues) relative to the
2. Remote control panel assembly
ship’s deck position and any obstructions that
may be present during launch and recovery 3. Hydraulic pump assembly
operations
4. Transformer assembly
4. Visual indications for helicopter in-flight
5. Glide slope indicator
refueling (HIFR) and vertical replenishment
operations (VERTREP) 6. Stabilized platform

5. A lighting system to signify any unacceptable Each of these components is discussed in detail in
landing condition aboard the ship the following paragraphs.

12-1
Figure 12-1.—Typical VLA installations with flight deck and hangar on 0-1, dual landing approach.

12-2
Figure 12-3.—Stabilized glide slope indicator system

12-3
 Figure 12-4.—Electronic enclosure assembly.

ELECTRONIC ENCLOSURE
ASSEMBLY

The electronic enclosure assembly (fig. 12-4)

contains the circuits, amplifiers, and other electrical and
electronic components required to control the major
components of the system. To understand the system
operation, it is necessary for you to understand the
operation of the feedback control systems. A feedback
control system compares an input signal with a
reference signal and then generates an error signal. This
error signal is then amplified and used to drive the output
in a direction to reduce the error. This type feedback
system is often referred to as a servo loop. A gyro (fig.
12-5), mounted on the stabilized platform, acts as the
reference of the system. Since the gyro is stable, synchro
transmitters located on the gimbals in the gyro will sense
Figure 12-5.—Platform pitch drive.
any motion of pitch or roll. As the ship begins to pitch

12-4
 Figure 12-6.—Block diagram-stabilization circuits.

or roll, an error signal is developed by the synchro

transmitter stators in the gyro. Refer to the block
diagram in figure 12-6, and you can follow the path of
the error signal through the electronic enclosure
assembly. (The block diagram represents either the
pitch or the roll control loops since they are identical
electrically.) From the transmitter stators of the gyro,
the error signal is sent to the gyro demodulator where
the signal is changed born ac to dc The signal then goes
through a stabilization lock (stab lock) relay (described
later) and is amplified as it moves through the servo
amplifier which in turn operates the servo valve. The
servo valve opens and allows hydraulic fluid to enter the
hydraulic actuator (fig. 12-7). This levels the platform
and thus cancels the error signal. When this occurs, a
READY light is actuated on the remote control panel.
If the system develops a malfunction and the error signal
is not canceled, an error-sensing circuit will light the
NOT READY light on the remote control panel and turn
off the glide slope indicator.
In the previous paragraph you have learned the Figure 12-7.—Stabilized platform assembly-functional
normal mode of operation in the electronics portion of diagram.
the system. The stabilization lock feature (stab lock

12-5
relay) tests and aligns the GSI. Referring to figure 12-8, signal comes from the linear voltage differential
you will see the: transformer (LVDT) when the test switch is in the off
position. The core of the LVDT is mechanically
1. internal gyro stab lock,
attached to the hydraulic actuator which levels the
2. the ship’s gyro stab lock push button, and platform. As the actuator moves, the core also moves,
3. two test switches thereby supplying a signal proportional to the amount
of roll or pitch. These signals can be measured to aid in
As previously mentioned the error signal in the the maintenance and alignment of the system.
normal mode goes through a stab lock relay. When the Provisions are also made to manually drive the platform
stab lock button is pushed, the normal error signal using the test switches and the manual drive
supplied from the gyro is stopped at this point. (See fig. potentiometer ((4) in fig. 12-8 and may also be seen in
12-9.) When the stab lock button is pushed, the error diagram of fig. 12-10).

Figure 12-8.—Component panel assembly.

12-6
Figure 12-9.—Stabilization control circuits—signal flow.

Figure 12-10.—LVDT servo loop.

12-7
 Figure 12-11.—Remote control panel assembly.

REMOTE CONTROL PANEL ASSEMBLY provides control and indicators for operating and
monitoring the stabilized GSI from a remote location.
The remote control panel (fig. 12-11) is located in It contains- the following items.
the helicopter control station (HCS). This panel

12-8
YDRAULIC PUMP ASSEMBLY Hydraulic fluid heaters in the oil reservoir will warm the
fluid up to 70°F ±5 degrees before use of the GSI
The hydraulic pump assembly (fig. 12-12) is located system.
as close as possible to the stabilized platform. It
provides hydraulic fluid at 1,400 psi to the hydraulic
actuator on the stabilized platform. ‘he motor and TRANSFORMER ASSEMBLY
controller operate on 440-V three phase received from
the ship’s normal power supply. The temperature The transformer assembly is located as close as
switches (not shown) operate the HIGH TEMP light on
possible to the stabilized platform. Its purpose is to step
the remote control panel. Also, a pressure switch in the
hydraulic pump discharge line will close at 1,200 psi. If down the voltage for the source light (GSI) from 0- to
not closed, the pressure switch will de-energize the 115- volts ac to 0- to 18.5-volts ac depending on the
electronic panel assembly on low oil pressure. setting of the intensity control.

Figure 12-12.—Hydraulic pump assembly.

12-9
Figure 12-13.—A. Glide slope Indicator; B. Lamp house assembly; C. Temperature control section.

12-10
 2. The light tunnel— provides space for the focal
length of the lens to be utilized
3. The temperature control section fig.
12-13C)—contains the Fresnel lens which iS
sensitive to temperature
To protect the Fresnel lens from excessive
temperature variations, two heaters, each having a
blower, are mounted on either side of the cell assembly
in the temperature control section. Each heater is
controlled by a thermostat which maintains the
Figure 12-14.—stabilized platform assembly. temperature at 115°F ±15 degrees. The blowers
recirculate the heated air throughout the cell assembly.

GLIDE SLOPE INDICATOR (GSl)

STABILIZED PLATFORM
ASSEMBLY
The glide slope indicator (fig. 12-13A) is a cell
assembly made up of the following three main sections: The stabilized platform assembly (fig. 12-14),
which will remain level despite the pitch and roll attitude
1. The lamp house assembly (fig. 12-13B)— of the ship, provides a mount for the GSI. The assembly,
contains three source lights, a vent fan to cool shown in figure 12-15, consists of a stabilized platform
the section, an optical lens (not shown), and attached to two hydraulic actuators (pitch and roll)
reflectors which maintain the platform level at all times. The

Figure 12-15.—Function diagram of the stabilized platform assembly.

12-11
block diagram in figure 12-16 shows the complete itself to the average pendulum position. Figure 12-18
system interconnected. The stabilized GSI system shows the essential elements of the gyro.
cannot compensate for a ship’s heave. Heave is the rise
and fall of the entire ship without a change in pitch or GYRO ALARM CIRCUIT
roll angle.
The stabilized GSI system incorporates an
independent failure detection circuit. This detects any
VERTICAL GYROSCOPE
failure that results from a loss of stabilization. It does
this by comparing an input from the ship’s gyro with the
The vertical gyroscope is basically a mechanical output of the platform LVDT. When the system is
device. The essential element of the gyroscope is a operating correctly in the internal gyro mode, the output
flywheel rotating at high angular velocity about an axis. of the LVDT is directly proportional to the ship’s
The flywheel is mounted within gimbals which allow it motion. If the ship’s motion from the LVDT is added out
2 degrees of freedom. (See fig. 12-17.) of phase (reverse polarity) to the ship’s motion from the
ship’s gyro, the two will cancel. Any remaining voltage
When the gyroscope’s flywheel is rotating at high
from the summation will be the error between the ship’s
speed, its inertia is greatly increased. This causes the
gyro and the platform. The error is compared against a
flywheel to remain stationary within the gyro gimbal
preset limit, and if it exceeds this limit, the platform
structure. In order to align the gyroscope flywheel to
error relay is tripped. The gyro input is required for the
the local earth’s gravity vector (downward pull of
alarm and is also used for the ship’s gyro stabilization
gravity), a pendulum sensor is attached under the
and for the rate lead. The rate lead circuits are used to
spinning flywheel. In operation, the pendulum is held
reduce velocity lag of the platform and to increase
suspended within a magnetic sensor. The magnetic
system dynamic accuracy. In the ship’s gyro
sensor measures the difference between the pendulum
stabilization mode, the system operates at a reduced
axis and the spin motor axis. The sensor output is
accuracy because of null errors and LVDT linearity
amplified and used to drive a torque motor. This motor
error. Therefore the ship’s gyro mode is to be used as a
causes the gyro flywheel to rotate in a direction that
backup mode only.
reduces the sensor output. In actual operation, the
pendulum sensor is affected by lateral accelerations HOMING BEACON
which cause it to oscillate about true position. To correct
for this oscillation, the gyro circuit’s time constants are The homing beacon is a high intensity white lamp
long. The long time constants cause the gyro flywheel located on the mainmast or high on the superstructure.
to ignore periodic variations of the pendulum and align It should be visible for at least 330 degrees in azimuth.
The beacon has a minimum effective intensity of 1,500
candles over a span of 7 degrees in elevation and
produces approximatey 90 flashes per minute. The
intensity of the beacon light can be varied from blackout
to full intensity by a dimmer control on the lighting
control panel. The homing beacon is wired in two
circuits; the motor which turns the reflector is wired to

Figure 12-16.—Stabilized glide slope indicator—block

diagram. Figure 12-17.—Vertical gyro-simplified schematic.

12-12
 Figure 12-18.—Vertical gyro—line schematic diagram.

a fixed-voltage circuit ( 115 volts), while the lamp ( 150 The primary is connected to a motor-driven, variable
watt) is wired through a step-down transformer ( 115/32 transformer (intensity) and a flash sequencer (fig.
volts) to a variable voltage dimming circuit. 12-19).

EDGE LIGHTS

The edge lights outline the periphery of the

obstruction-free helicopter deck area with a minimum
of four lights along each edge of the area. Edge lights
are red omnidirectional lamps which can be seen in any
direction above deck level. They are connected to the
low voltage side of a 115/12-volt step-down
transformer. The 115-volt side of each transformer (one
transformer per light fixture) is connected to a
motor-driven variable transformer which controls the
intensity of the lights.

LINE-UP LIGHTS

The line-up lights are white and flash in sequence.

They are installed in the deck along the line-up line for
deck landing. Line-up lights are either unidirectional or
bidirectional (LSTs only) dependent on the ship’s
landing capability. Each lamp is connected to the
secondary side of a 115/6.5-volt step-down transformer. Figure 12-19.—Simplified interconnection of line-up lights.

2-13
EXTENDED LINE-UP LIGHTS FORWARD STRUCTURE/DECK
SURFACE FLOODLIGHTS

Extended line-up lights are white lights installed at

White floodlights, with red filters, are provided to
the forward end of the deck-installed line-up lights and
illuminate any structure forward of the landing area and
extend above the flight-deck level. These lights merely
to provide greater depth perception to the pilot during
extend the line-up lights forward to provide the night operations. At least two fixtures, one port and one
helicopter pilot with a better visual picture of line up starboard, must be installed and adjusted to illuminate
with information during night landing operations. the aft face of the hangar as well as structures forward
The extended line-up lights are a minimum of six of the landing area. Other fixtures are installed and
adjusted to illuminate the landing area itself. These
individual light fixtures either mounted vertically to a
fixtures are connected to a motor-driven variable
bulkhead or on a light bar assembly mounted to the flight
transformer (intensity). Each fixture is conncted to the
deck. Each extended line-up light fixture is connected low voltage side of a separate 120/30-volt step-down
to a 6.5-volt secondary of a 120/6.5-volt step-down transformer.
transformer. The primaries of the transformers are
connected to the same circuit as the deck-installed,
MAINTENANCE FLOODLIGHTS
line-up lights.

Red maintenance floodlights are required for night

FLASH SEQUENCER preflight and postflight maintenance. The floodlight
assembly consists of a light fixture, lamp, red filter,
on/off switch, and support. The light is wired to the
The flash sequencer (fig. 12-20) is wired into the ship’s 120-volt, 60Hz, single-phase power supply.
line-up lights to provide the helicopter pilot with
additional visual cues and depth perception during night
OVERHEAD FLOODLIGHTS
landing approaches. The cam-operated unit
sequentially flashes 9 to 10 line-up lights. On ships with
White overhead floodlights with yellow and red
both port and starboard approaches, the flash sequencer filters provide illumination of the helicopter deck for
must be capable of producing flashes (strobing) of either support of night operations. These lights are mounted
port or starboard line-up lights as selected by controls above the landing area and are connected to a
on the lighting control panel. motor-driven variable transformer.

VERTICAL DROP-LINE LIGHTS WAVE-OFF LIGHT SYSTEM

The Wave-Off Light (WOL) System (fig. 12-21)

Vertical drop-line lights are red and serve as an aft
provides a visual cue to the pilot that landing conditions
extension of the deck-installed line-up lights. The light aboard the ship are unacceptable. The system consists
bar assembly is installed immediately aft of the landing of the following nine major components:
line-up lights and contain four to six red lights which
1. Master control panel assembly
extend below the flight deck in the vertical plane. These
lights in conjunction with the extended line-up lights 2. Two remote panel assemblies
provide the helicopter pilot with continuous line up 3. Two plug-in junction box assemblies
during night approach when deck-installed line-up
4. Terminal junction box assembly
lights cannot be seen because of the ship’s motion. The
5. Two wave-off light assemblies
drop-line bar assembly operates from a single
120/12-volt step-down transformer/enclosure assembly 6. Portable switch
which is wired to a motor-driven, variable voltage Each of these components is discussed in detail in
transformer (dimmer). the following paragraphs.

12-14
Figure 12-20.—Flash sequencer panel and timer assembly.

12-15
 Figure 12-21.—Wave-off light system.

MASTER CONTROL PANEL

The master control panel (fig. 12-22) is located in

the Helicopter Control Station. It controls the power for
the WOL, houses the electronic circuitry which controls
intensity and flash rate of the WOL, permits operation
of the WOL, and indicates which station has control.

REMOTE PANEL ASSEMBLY

The remote panel assembly (fig. 12-23) allows the

WOL to be operated from remote stations located at the
captain’s bridge and adjacent to the hanger door.

PLUG-IN JUNCTION BOX ASSEMBLY

Two plug-in junction boxes are contained in one

assembly. The junction boxes are located one on either
side of the hangar door to permit a plug in of a portable
switch to operate the WOL on the flight deck by the
landing signalman enlisted (LSE). Figure 12-22.—Master control panel.

12-16
 TERMINAL JUNCTION BOX
ASSEMBLY

The terminal junction box assembly contains the

terminals for the connections to the WOL and the master
control panel.

WAVE-OFF LIGHT ASSEMBLY

The wave-off lights are located on each side of the

GSI. Figure 12-24 shows interconnection of the WOL
system.

HELICOPTER IN-FLIGHT REFUELING

LIGHTS (HIFR)

Helicopter in-flight refueling lights are yellow (red

if at war or other conditions where reduced visibility is
Figure 12-23.—Remote panel assembly. required) and are required for helicopter refueling

Figure 12-24.—Wave-off light system.

12-17
operations. These lights give the helicopter pilot a VERTICAL REPLENISHMENT
visual indication of the ship’s heading at all times and (VERTREP) LIGHTS
provide a height reference during in-flight refueling
VERTREP line-up lights are bidirectional fixtures
operations.
for VERTREP/hover approaches, and they form an
Three HIFR heading lights are installed forward to athwartship line-up path at approximately 8- to 12-foot
aft on the port side of the ship in a line parallel to the intervals. Spacing between lights is uniform and such
ship’s centerline (heading). Spacing between the lights that the pilot’s view of the lights is not obstructed during
is approximately 20 feet, beginning outside the rotor the helicopter’s approach. When installed in landing
clearance distance and extending forward. All HIFR areas equipped with landing approach line-up lights, the
heading lights are installed at the same height, VERTREP line-up lights are connected to the same
approximately 30 to 40 feet above the ship’s waterline. dimmer as the landing approach line-up lights. This
All lights are controlled by a single on/off switch, switching arrangement prevents the simultaneous
located on the lighting control panel, and area standard energizing of both the landing approach line-up lights
watertight assembly consisting of a lighting fixture, and the VERTREP/hover line-up lights.
yellow globe, and a 115-volt, 50-watt rough service
lamp. LIGHTING CONTROL PANEL

The lighting control panel (fig. 12-25) that controls

the lights in the VLA package is installed on all ships

Figure 12-25.—Lighting control panel.

12-18
 figure 12-26.—Simplified line diagram of the lighting control panel.

which conduct helicopter operations at night. This 2. Line-up lights

control panel is located at the helicopter control station
3. Vertical drop-line lights
and consists of switches, dimmers, and red indicator
lamps. The dimmers are variable autotransformers 4. Edge lights
mounted in the control panel. The lighting control panel
Input power is applied to the variable transformer,
requires input power at 120 volt, 60 Hz and is designed
and the controlled 0- to 120-volt-ac output is connected
to accommodate the applicable light equipment
discussed in the preceding paragraphs. Figure 12-26 is
a simplified line diagram of the lighting control panel.

MOTOR-DRIVEN VARIABLE
TRANSFORMERS

Motor-driven remote variable transformers (fig.

12-27) are used in the VLA lighting control system to
control the intensity of the various lights. There are four
10-ampere and two 22-ampere transformers in the
system. The 22-ampere transformers are used with the
overhead and deck-surface floodlights and the
10-ampere transformers are used with the following
lights:

1. Hangar illumination floodlights Figure 12-27.—Motor-driven variable transformer.

12-19
to the lights (fig. 12-28). The transformer wiper until the feedback voltage equals the reference, and the
(secondary) is moved by the synchronous motor which motor stops at a position corresponding to the desired
is controlled by the potentiometer in the lighting control light intensity. Cam-operated limit switches open the
panel. The detector circuit in the position detector motor circuit and prevent the motor from driving the
determines from the setting of the remote control wiper on the transformer beyond the upper and lower
potentiometer whether the motor turns in a direction to stops.
raise or lower the output voltage.
The reference power supply in the position detector MAINTENANCE REQUIREMENTS
converts ac input voltage to dc, and the potentiometer in
the control panel determines the magnitude of dc The VLA system contains many electrical and
reference voltage sent to the detector circuit. The electronic components which require both preventive
feedback power supply in the position detector converts and corrective maintenance. The components that we
the ac output voltage from the variable transformer to a have discussed in this chapter contain many motors,
proportional dc voltage which is also sent to the detector controllers, blowers, heaters, pressure switches, and
circuit. lighting fixtures that are exposed to weather. The
electronic portions are solid state and are primarily on
The detector circuit consists of a comparator and printed circuit boards. As an Electrician’s Mate you can
solid state switches (TRIACS) which energize either the realize some of the problems which will be encountered
clockwise (LOWER) or counterclockwise (RAISE) both with electrical and electronic parts. It is of utmost
windings of the drive motor. The drive motor rotates importance that you follow all PMS requirements
the wiper shaft on the transformer in the proper direction carefully to keep all portions of this system operating

Figure 12-28.—Motor-driven remote variable transformer circuit diagram.

12-20
effectively. When performing any corrective action, lighting systems installed on U.S. Navy air capable
always refer to the manufacturer’s technical manuals. ships. Remember, just as we have different classes of
ships, we have different types of lighting systems. As an
SUMMARY E-6 or E-7 you may be required to supervise the
Now that you have completed this chapter, you maintenance of several different systems. Always refer
should have a good comprehension of the various to the correct technical manual for that particular ship.

12-21
 CHAPTER 13

ENGINEERING PLANT OPERATIONS,

MAINTENANCE, AND INSPECTIONS

In today’s environment of decreasing resources and maintaining, and operating the various equipment
manpower, it is essential that equipment be well needed to keep the ship functional.
maintained and people be properly trained. This chapter
will give you some idea of the scope of activity required OPERATION RESPONSIBILITIES
to keep today’s engineering plant operable and ready.
The engineering department administrative
LEARNING OBJECTIVES organization is set up to provide the proper assignment
of duties and supervision of personnel. Personnel,
Upon completion of this chapter, you will be able to including yourself, are needed to ensure that all
do the following: pertinent instructions are carried out and that all
1. Identify the various forms, records and reports machinery, equipment, and electrical systems are
required to operate an engineering plant. operated following good engineering practices. Other
responsibilities include the posting of instructions and
2. Recognize the need for preventive maintenance. safety precautions by operational equipment and
3. Identify the various forms used in reporting and ensuring that they are obeyed by all personnel.
tracking maintenance actions. WatchStanders must be properly supervised to ensure
that the entire engineering plant is operated with
4. Identify the various types of inspections maximum reliability, efficiency, and safety.
conducted and realize their importance.
For you to monitor and record your plant’s status
5. List the various ship trials conducted.
and performance, you need to know which engineering
6. Identify the responsibilities of various members records and reports are required. Reports regarding
in and out of the command for enforcing safety administration, maintenance, and repair of naval ships
guidelines. are prescribed by directives from authorities such as the
Type Commander, Naval Ship Systems Command
Although it is possible to consider operations,
(NAVSEA) and the Chief of Naval Operations (CNO).
maintenance, and inspections as three separate areas of
These records must be accurate and up to date following
responsibility, it is important to remember that the three
current instructions.
cannot be totally separated. Much of your work requires
you to operate equipment, maintain it for further use, As an EM1 or EMC, you will have supervisory
and keep auditable records on the equipment. duties that require you to have a greater knowledge of
engineering records and administrative procedures than
you had as an EM3 or EM2. Supervisory duties and
ENGINEERING PLANT
responsibilities require a knowledge of engineering
OPERATIONS
records as well as inspections, administrative
The primary goal of a ship is to get underway. In procedures, training, preventive maintenance, and
meeting that objective, the engineering department repair procedures.
functions to ensure that the engineering plant is fully
Information on the most common engineering
functional, can be safely operated, and adequate watch
records and reports is given in this chapter. These
teams are trained and qualified.
standard forms are prepared by the various systems
As a member of the engineering department, you commands and CNO. The forms are for issue to forces
will be responsible for ensuring that the equipment afloat and can be obtained as indicated in the Navy Stock
under your cognizance is ready to support the ship in List of Publications and Forms, NAVSUP 2002. Since
getting underway. Once underway, the engineering these forms are revised periodically, you must be sure
department continues its job of monitoring, that you are using the most current version. When

13-1
complementary forms are necessary for local use, make f. Such other matters as may be specified by
sure that an existing standard form will serve the competent authority
purpose. Each entry must be a complete statement and must
be written using standard phraseology. The TYCOM’s
OPERATING RECORDS directives contain other specific requirements
pertaining to the remarks section of Engineering Logs
In operating equipment, care must be taken to for ships of the type. The engineering officer must
ensure that the equipment is operated within guidelines ensure compliance with these directives.
or boundaries established by the manufacturer.
Operating records (logs) allow for tracking the Entries in the Engineering Log must be made
condition of equipment and tracking the number of following instructions given in the following
hours of operation. These are legal records and must be documents:
maintained as described.
• The Log Sheet, NAVSEA 3120/2B

Engineering Log • U.S. Navy Regulations, chapter 10

• Naval Ship’s Technical Manual, chapter 090

The Engineering Log, NAVSEA 3120/2 (fig. 13-1),
and the Log Continuation Sheet, NAVSEA 3120/2, are • TYCOM directives
used to record important daily events and data pertaining
The original Engineering Log is a legal record. As
to an engineering department and the operation of an
such, it must be prepared neatly and legibly. The
engineering plant. A table is provided in the log for
remarks should be prepared, and must be signed, by
recording the hourly average rpm (to the nearest tenth)
the engineering officer of the watch (EOOW)
of all shafts and the resultant speed in knots. Additional
(underway) or the engineering department duty officer
tables and spaces are provided for recording the
(in port). No erasures are permitted in the log. When
information that is listed below.
a correction is necessary, a single line is drawn through
1. Name of the ship. the original entry so that the entry remains legible. The
correct entry is then inserted so clarity and legibility are
2. Date.
maintained. Corrections, additions, or changes are
3. Ship’s draft and displacement (upon getting made only by the person required to sign the log for the
under way and anchoring or mooring). watch. Corrections are initialed on the margin of the
4. Total engine miles steamed for the day and the page.
distance traveled through water.
The engineering officer verifies the accuracy and
5. Number of days out of dock. completeness of all entries and signs the log daily. The
CO approves and signs the log on the last calendar day
6. Amount of fuel, water, and lubricating oil on
of each month and on the date his/her command is
hand, received and expended.
relinquished. The engineering officer should require
7. Location or route of the ship. the log sheets be submitted in sufficient time to allow
8. Remarks relating to important events. Remarks his/her review and signature before noon of the first day
written in the Engineering Log must include the following the date of the log sheet(s).
following information
When the CO (or engineering officer) directs a
a. Boilers in use change or addition to the Engineering Log, the person
concerned must comply unless he/she believes the
b. Engine combination in use
proposed change or addition to be incorrect In this
c. Major speed changes (such as 1/3, 2/3, event, the CO (or engineering officer) enters such
standard, and full) remarks over his signature as deemed appropriate. After
the log has been signed by the CO, no change is
d. All injuries to personnel occurring within the
permitted without the CO’s permission or direction.
department
e. Casualties occurring to material under the Completed Engineering Log sheets are filed in a
responsibility of the engineering department post-type binder. Pages of the log are numbered

13-2
Figure 13-1.—Engineering Log—all ships.

13-3
Figure 13-2.—Engineer’s Bell Book, NAVSEA 3120/1.

13-4
consecutively with a new series of page numbers recorded in column 4 in feed and fractions of feet. These
beginning on the first day of each month are set in response to a signaled speed change, rather
than the shaft revolution counter readings. The entries
Engineer’s Bell Book, NAVSEA 3120/1 for astern pitch are preceded by the letter B. Each hour
on the hour, entries are made of counter readings. This
The Engineer’s Bell Book (fig. 13-2) is a record of facilitates the calculation of engine miles steamed
all bells, signals, and other orders received by the during those hours when the propeller pitch remains
throttleman regarding movement of the ship’s constant at the last value set in response to a signaled
propellers. Entries are made in the Bell Book by the order.
throttleman (or an assistant) as soon as an order is
received Entries may be made by an assistant when the Before going off watch, the EOOW signs the Bell
ship is entering or leaving port or engaging in any Book on the line following the last entry for the watch.
maneuver which is likely to involve numerous or rapid The next EOOW continues the record immediately
speed changes. This procedure allows the throttleman thereafter. In machinery spaces where an EOOW is not
to devote undivided attention to answering the signals. stationed, the bell sheet is signed by the watch
The Bell Book is maintained as shown in figure 13-3. supervisor.

On ships and craft equipped with controllable The Bell Book is maintained by bridge personnel in
reversible pitch propellers, the propeller pitch is ships and craft equipped with controllable reversible

1. A separate bell sheet is used for each shaft each day, except where more than one shaft is controlled by the
same throttle station. In this case, the same bell sheet is used to record the orders for all shafts controlled by the
station. All sheets for the same date are filed together as a signal record.
2. The time of receipt of the order is recorded in column No. 1 (fig. 13-2).
3. The order received is recorded in column No. 2. Minor speed changes (generally received via revolution
telegraph) are recorded by entering the number of rpm ordered. Major speed changes (normally received via engine
order telegraph) are recorded using the following symbols:

4. The number of revolutions corresponding to the major speed change ordered is entered in column 3.
NOTE: When the order received is recorded as rpm in column 2 (minor speed changes), no entry is made in column
3.
5. The shaft revolution counter reading (total rpm) at the time of the speed change is recorded in column 4. The
shaft revolution counter reading—as taken hourly on the hour, while under way—also is entered in column 4.

Figure 13-3.—Maintaining the Engineer’s Bell Book

13-5
pitch propellers and in which the engines are directly in the engine room indicates the time that control is
controlled from the bridge. When control is shifted to taken by the engine room. Similarly, the last entry made
the engine room, however, the Bell Book is maintained by the engine room personnel indicates when control is
by the engine room personnel. The last entry made in shifted to the bridge. When the Bell Book is maintained
the Bell Book on the bridge indicates the time that by the bridge personnel, it is signed by the officer of the
control is shifted. The first entry made in the Bell Book

Figure 13-4.—Fuel and Water Report (front).

13-6
deck (OOD) in the same manner as prescribed for the by the EOOW, the OOD, or the watch supervisor, as
EOOW. appropriate.

Alterations or erasures are not permitted in the Fuel and Water Reports, NAVSEA 9255/9
Bell Book. An incorrect entry is corrected by drawing a
single line through the entry and recording the correct The Fuel and Water Report (figs. 13-4 and 13-5), is
entry
. on the following line. Deleted entries are initialed a report submitted daily to the commanding officer.

Figure 13-5.—Fuel and Water Report (back).

13-7
This report indicates the amount of fuel oil and water on report of engineering data. From this report the
hand as of midnight, the previous day. The Fuel and operating efficiency and general performance of the
Water Report also includes the previous day’s feed and ship’s engineering plant can be calculated (see fig.
potable water performance and results of water tests. 13-6). Requirements for this report are contained in
The original and one copy are submitted to the OOD in Fleet Commander Instructions. This report is prepared
sufficient time for submission to the commanding by the engineer officer and verified, as to fuel receipts,
officer or command duty officer with the 1200 reports. by the supply officer. It is then approved and fowarded
by the CO directly to the fleet commander. A copy is
Monthly Summary, CINCLANTFLT 3100-4
retained on board in the files of the engineering
The Monthly Summary of Fuel Inventory and department. An additional copy of the report may be
Steaming Hours Report is a comprehensive monthly provided to the type commander.

Figure 13-6.—Monthly Summary of Fuel and Steaming Hours Report, CINCLANTFLT Report 3100-4.

13-8
AC/DC Electric Propulsion Operating Information is entered in the record and the remarks
Record, NAVSEC 9622/1 are written and signed by the EM of the watch.
Accuracy is checked by the EM in charge of the electric
The AC/DC Electric Repulsion Operating Record, propulsion equipment and the electrical officer. Space
NAVSEC 9622/1, is a daily record for each operating is provided on the record for the approval and signature
propulsion generator and motor in ships (except of the engineer officer on a daily basis.
submarines) equipped with ac or dc electric propulsion
machinery. A separate sheet is used for each shaft, Electrical Log, NAVSEC 9600/1
except on ships with more than two generators or two
motors per shaft. In this case, as many sheets as needed The Electrical Log (fig. 13-7) is a complete daily
are used. record maintained for each operating ship’s service and

Figure 13-7.—Electrical Log—Ship’s Service Electric Plant.

13-9
emergency generator. It is a complete daily record generator sets) should be recorded on the form. The IC
(from midnight to midnight) of the operating conditions room operating record is checked and approved in the
of the ship’s service electric plant. Any corrections or manner described for the Gyrocompass Operating
changes to entries for a watch must be made by the Record.
person who signs the log for that watch. However,
corrections or additions must not be made after the log ADDITIONAL RECORDS
sheet has been signed by the engineering officer without
his or her permission or direction. The station logs are The engineering records and reports discussed in
turned into the logroom every morning for the this section serve to inform responsible personnel of
engineering officer’s signature and for filing. coming events (including impending casualties), supply
data for the analysis of equipment performance, and
The back of the log is a continuation of the front,
provide a basis for design comparison and
and it also provides spaces for the engineering officer’s
improvement. They also provide information for the
and senior Electrician’s Mate’s signatures. Entries
improvement of maintenance techniques and the
concerning the prime movers are generally recorded by
development of new work methods. The records are
the generator watch (MM). Electrical information is
those papers required to be compiled and retained on
recorded by the switchboard watch (EM) who signs the
board (in original or duplicate form) for prescribed
remarks for the watch.
periods of time. This is primarily for reference in
The accuracy of the entries is checked by the EM in administrative and operational matters. The reports are
charge of the ship’s service generators. Both the M and of either a onetime or recurring nature. Recurring
E division officers check the record for accuracy and reports are required at prescribed or set intervals.
any evidence of impending casualties. Each officer Onetime reports need be made when a given situation
initials the record to indicate that it has been checked. occurs.
The engineering officer notes the content and signs the
record in the space provided on a daily basis. Engineering Officer’s Night Order Book

Gyrocompass Operating Record The engineering officer keeps a Night Order Book
(fig. 13-8) which is preserved as a part of the
The Gyrocompass Operating Record engineering records. Entered into the Night Order Book
(Gyrocompass Log) is a locally prepared, complete are the engineer officer’s orders with respect to the
daily record maintained for each operating master following:
gyrocompass. The form for the log is prepared 1. Operation of the engineering plant
following the type commander’s directives. Columns
in the log should provide space for recording the times 2. Any special orders or precautions concerning
of starting and stopping the gyrocompass, total hours of the speed and operation of the main engines
operation since delivery of the gyrocompass, and 3. All other orders for the night for the EOOW.
important operating data pertaining to the gyrocompass
installation. The petty officer in charge of the interior The Night Order Book is prepared and maintained
following instructions issued by the type commander.
communications (IC) equipment checks the accuracy of
the log, and the electrical officer notes its contents on a Some instructions specify that the Night Order Book use
daily basis. a specific format that is standard for ships of the type.
Other commands allow use of a locally prepared form
but specify certain contents of the book
IC Room Operating Record
The Engineering Officr’s Night Order Book must
The IC room operating record is a daily record of contain orders covering routine situations of a recurring
major electrical equipment in operation in the IC room nature (engineering department standing orders) as well
and is maintained by the IC watch. The form for the as orders for the night for the EOOW. Standing orders
record is prepared locally following the type are issued by the engineer officer as a letter-type
commander’s directives. On small ships the directive (instruction) following the ship’s directives
Gyrocompass Log and the IC room record may be system. A copy of the instruction is posted in the front
maintained on the same form. Important data such as of the Night Order Book Orders for the night for the
voltages and currents of major units of IC equipment (IC EOOW generally specify the boilers and other major
switchboard, telephone switchboard, and motor items of machinery to be used during the night watches.

13-10
Figure 13-8.—Sample Engineering Officer’s Night Orders.

13-11
Figure l3-9.—Steaming Orders (sample).

13-12
A form similar to the one shown in figure 13-8 is in use Publications and Forms, NAVSUP 2002. The
in some ships for the issuance of the engineering requisition for the new book must show the mark,
officer’s night orders. modification and serial numbers of the gyrocompass
for which the book is intended.
The Night Order Book is maintained in port and at
sea. In the temporary absence of the engineer officer in
Degaussing Folder
port the book may be maintained by the engineering
department duty officer. When the ship is under way,
The ship’s Degaussing Folder is a record of the
the Night Order Book is delivered to the EOOW before
degaussing installation in the ship. The folder contains
2000 and is returned to the log room before 0800 of the
the following information:
following day. In addition to the EOOW, principal
engineering watch supervisors and the oil king should 1. A description of the degaussing installation
read and initial the night orders for the watch. In port,
2. A record of inspection, tests, and repairs
the night orders should be read and initialed by the
performed by repair activities
leading duty petty officer of each engineering division
as well as by the principal watch supervisors. 3. The values of all coil currents for the ship’s
positions and headings
Steaming Orders
4. A record of the degaussing range runs.

Steaming Orders are written orders issued by the The Degaussing Folder is necessary for the
engineering officer. These list the major machinery operation of the degaussing system and must be
units and readiness requirements of the engineering safeguarded against loss. Generally, the Degaussing
department based upon the time set for getting the ship Folder is in the possession of the navigator. The
under way. Generally, a locally prepared form similar engineer officer provides the navigator with the names
to the one illustrated in figure 13-9 is used for issuance of the engineering personnel who will require access to
of the Steaming Orders. The orders normally specify the folder.
the following information:
The Ship’s Force Degaussing Maintenance Record,
1. The engine combinations to be used NAVSHIPS 1009, is provided for recording
maintenance of the degaussing system performed by the
2. Times for lighting fires and cutting-in boilers
ship’s force. When they are completed, the forms are
3. Times for warming up and testing main engines inserted in the degaussing folder.
4. Times for starting and paralleling ship’s service
generators Situation Reports

5. Standard speed, and (6) EOOW and principal Situation reports (SITREPS) are onetime reports
watch supervisors required in certain situations. Table 13-1 is a summary
Early posting of Steaming Orders is essential to of onetime reports (not previously described) pertaining
getting a ship with a large engineering plant underway to the engineering department.
with a minimum of confusion.
Gas Turbine Service Records
Gyrocompass Service Record
The gas turbine propulsion plants are unique in that
The Gyrocompass Service Record Book is service and maintenance records are similar to aircraft
furnished the ship with each gyrocompass (except the propulsion plants. Naval Ship’s Technical Manual,
Mk 22) installed. The book is a complete record of chapter 234 (9416), gives a description of these service
inspections, tests, and repairs to the gyrocompass. The records and full instructions for maintaining them.
Gyrocompass Service Record must always remain
with its associated gyrocompass. Complete DISPOSAL OF ENGINEERING RECORDS
instructions for maintaining the record are outlined in AND REPORTS
the front of the book and must be carefully followed. In
the event of loss of, or damage to, the Gyrocompass Before any of the engineering department records
Service Record Book, a replacement book can be are destroyed, the Disposal of Navy and Marine Corps
obtained as indicated in the Navy Stock List of Records, USN and USNS vessels, SECNAVINST

13-13
Table 13-1.—Summary of Situation Reports

13-14
P5212.5(revised), should be studied. This publication PREVENTIVE MAINTENANCE
informs ships of the Navy of the procedures used for SYSTEM (PMS)
disposing records. For each department aboard ship,
these instructions list the permanent records that must The primary objective of the Navy Ship’s
be kept and the temporary records which may be Maintenance and Material Management Systems (3-M
disposed of following an established schedule. Systems) is to provide a means for managing
maintenance and maintenance support so that
Both the Engineering Log and Engineer’s Bell Book
equipment is maintained in a state of maximum
must be preserved as permanent records on board ship
equipment operational readiness. OPNAVINST
for a 3-year period unless they are requested by a Naval
4790.4, contains all of the detailed procedures and
Court or Board or by the Navy Department. In such
instructions for the effective operation of the 3-M
case, copies (preferably photostatic) of such sheets or
Systems. Other instructions on the 3-M Systems are
parts of these records that are sent away from the ship
found in the type commander’s maintenance manuals.
are certified by the engineering officer as being true
copies for the ship’s files. This section of the chapter contains a discussion of
the most cpmmon records of the 3-M Systems that must
At regular intervals, such as each quarter, the parts be kept current in the engineering department.
of those records that are over 3 years old are destroyed.
When a ship that is less than 3 years old is PLANNED MAINTENANCE SCHEDULES
decommissioned, the current books are retained. If a
ship is scrapped, the current books are forwarded to the In an effective Planned Maintenance System (PMS)
nearest Naval Records Management Center. Program, careful attention must be given to the PMS
schedules to ensure that they are accurately filled out
All reports forwarded to and received from
and posted in a timely manner. PMS schedules are
NAVSEA or other higher echelon commands may be
categorized as cycle, quarterly, and weekly.
destroyed when 2 years old, if no longer required.

Only those reports which are required or serve a Cycle Schedule

specified purpose should be maintained on board ship.
The Cycle PMS Schedule (fig. 13-10) displays the
However, any report or record that may help personnel
planned maintenance requirements to be performed
schedule or make repairs and that will supply personnel
between major overhauls of the ship. The following
with information not contained in publications or
information must be filled in on the cycle schedule:
manuals should also be kept on board.
ship’s name and hull number, work center designator
code, maintenance index page (MIP) number,
component or systems name, and maintenance
ENGINEERING PLANT scheduled in each quarter after overhaul.
MAINTENANCE
The engineering officer must supervise all cycle
Naval ships, submarines, and aircraft are becoming scheduling of engineering departmental maintenance,
more and more complex. To ensure these craft are ready then sign and date the Cycle PMS Schedule before it is
to fulfill their assigned mission, the engineering plant of posted.
each must be kept operational.
If the need to rewrite the Cycle PMS Schedule
The purpose of maintenance is to ensure that the arises, the old schedule should be filed with the last
equipment is ready for service at all times. The three quarterly schedule with which it was used.
fundamental rules for the maintenance of electrical
equipment are as follows: Quarterly schedule

1. Keep equipment clean and dry. The Quarterly PMS Schedule (fig. 13-11) is a visual
display of the workcenter’s PMS requirements to be
2. Keep electrical connections and mechanical
performed during a specific 3-month period. Spaces are
fastenings tight.
provided for entering the work center, quarter after
3. Inspect and test at sufficiently short intervals to overhaul, department heads signature, data prepared,
ensure that the equipment is in operating and the months covered. Thirteen columns, one for each
condition. week in the quarter, are available to permit scheduling

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 Figure 13-10.—Cycle PMS Schedule.

Figure 13-11.—Quarterly PMS Schedule.

13-16
of maintenance requirements on a weekly basis The Weekly PMS Schedule contains blank spaces
throughout the quarter. There are also columns to enter for the following information: work center code, date of
the MIP number and PMS requirements that may current week, division officer’s signature, MIP number
require rescheduling. There are “tick” marks across the minus the date code, component names, names of
top of the scheduling columns for use in showing the personnel responsible for specific maintenance items,
in-port/underway time of the ship for the quarter. periodicity codes of maintenance requirements,
outstanding major repairs, and situation requirements.
The engineering officer must supervise scheduling
of PMS on the quarterly schedule for his/her The workcenter supervisor is responsible for
department, then sign and date the schedule before it is completing the Weekly PMS Schedule and for updating
posted. At the end of each quarter, the engineer officer it every day.
must review the quarterly schedule, check the reasons
for PMS actions not accomplished, and sign the form in SCHEDULING WORK
the space provided on its reverse side. The division
Careful planning is required to keep up with all
officer is responsible for updating the quarterly schedule
maintenance and repair work within your division. You
every week. Completed quarterly schedules should be should already have in your workcenter the following
kept on file for 1 year. documents to help you schedule your work:
Weekly Schedule
• The Current Ship’s MaintenanceProject
The Weekly PMS Schedule (fig. 13-12) is a visual
(CSMP)
display of the planned maintenance scheduled for
accomplishment in a given workcenter during a specific • The Job Control Number (JCN) Log
week. The weekly schedule is used by the workcenter
• The Quarterly PMS Schedule
supervisor to assign and monitor the accomplishment of
required PMS tasks by workcenter personnel. • The Weekly schedule

Figure 13-12.—Weekly PMS Schedule.

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 Figure 13-13.—Current Ship’s Maintenance Project (CSMP).

• The Maintenance Data Collection Subsystem entered into the Maintenance Data System (MDS) for a
(MDCS) Forms, such as OPNAV 4790/2K, particular unit. The CSMP can be divided by unit,
OPNAV 4790/2L, and OPNAV 4790/2Q. department, division, and workcenter. It is a valuable
tool for the workcenter supervisor when scheduling
Current Ship’s Maintenance Project (CSMP) work to conform to the ship’s schedule.
The CSMP (fig. 13-13) is a computer generated
document listing the maintenance actions that have been

Figure 13-14.—Recommended format for the job control number log.

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Job Control Number (JCN) Log Ship’s Maintenance Action Form
(OPNAV 4790/2K)
The JCN log (fig. 13-14) is a locally generated log
used by the workcenter to assign workcenter Job OPNAV Form 4790/2K (fig. 13-15) is used to show
Sequence Numbers (JSNs) to maintenance actions completion of specific PMS requirements; to request
required within the workcenter. These numbers enable repair of equipment or services from IMAs or shipyards;
each work item to individually tracked and its progress or can be used to describe equipment malfunctions.
to be monitored. Once submitted, the information from the 4790/2K will

Figure 13-15.—Ship’s Maintenance Action Form, OPNAV 4790/2K.

13-19
be entered into the MDS to appear on the units CSMP Supplemental Form (OPNAV 4790/2L)
for that workcenter which reported the action.
If the information is used to defer a maintenance OPNAV Form 4790/2L (fig. 13-16) is a
action for outside assistance, the responding repair supplemental form which you use to provide amplifying
facility will use this information to perform repairs information relating to a maintenance action described
required. on a corresponding 4790/2K. The OPNAV 4790/2L

Figure 13-16.—Supplemental Form, OPNAV 4790/2L.

13-20
may also be used to list multiple-item serial numbers is in your CSMP suspense file. For more detailed
and locations for which identical maintenance information about these forms and schedules and how
requirements exist from an outside activity. It may also
to fill them out, review OPNAVINST 4790.4 (fig.
be used to list drawings and sketches.
13-17).
Automated Ship’s Maintenance Action
Methods for Scheduling Work
Form, OPNAV 4790/2Q
Some of the proven methods you should follow
OPNAV Form 4790/2Q is an automated work
request produced by an IMA with computer capabilities. when scheduling maintenance and repair work are listed
The 2Q is produced from the original 4790/2k, which below.

Figure 13-17.—Automated Ship’s Maintenance Action Form, OPNAV 4790/20.

13-21
 1. Size up each job before you let anyone start defects or flaws, explain what is wrong, why it is wrong,
working on it. Check the applicable Maintenance and how to avoid similar mistakes in the future.
Requirement Cards (MRCs) so that you will know
exactly what needs to be done. Also, check all ESTIMATING WORK
applicable drawings and manufacturer’s technical
manuals. Often, you’ll be required to estimate the amount of
time, the number of personnel, and the amount of
2. Check on materials before you start. Be sure
material required for specific repair jobs. Actually, you
that all required materials are available before your
are making some kind of estimate every time you plan
personnel start working on any job. Do not overlook
and start a repair job as you consider such questions as
small items—nuts, bolts, washers, packing and gasket
the following:
materials, tools, measuring devices, and so forth. A
good deal of labor can be saved by making sure that How long will it take?
materials are available before beginning the job. An
Who can best do the job?
inoperable piece of machinery may be useless, but it can
become a nuisance and a safety hazard if it is spread How many people will be needed?
around the engine room in bits and pieces while you wait
Are all necessary materials available?
for the arrival of repair parts or materials.
However, there is one important difference between
3. Check the priority of the job and that of all other
the estimates you make for your own use and those that
work that needs to be done.
you make when your division officer asks for estimates.
4. When assigning work, carefully consider the When you give an estimate to someone in authority over
capabilities and experience of your personnel. As a rule, you, you cannot tell how far up the line this information
the more complicated jobs should be given to the more will go. It’s possible that an estimate you give to your
skilled and more experienced people. However, when division officer could ultimately affect the operational
possible, less experienced people should be given schedule of the ship; therefore, it’s essential that such
difficult work to do under supervision so that they may estimates be as accurate as you can possibly make them.
acquire skill in such jobs.
Many of the factors that apply to scheduling all
Be sure that the person who is going to do a job is maintenance and repair work apply also to estimating
given as much information as necessary. An the time that will be required for a particular repair job.
experienced person may need only a drawing and a You cannot make a reasonable estimate until you have
general statement concerning the nature of the job. A sized up the job, checked on the availability of materials,
less experienced person is likely to require additional checked on the availability of skilled personnel, and
instructions and, as a rule, closer supervision. checked on the priority of the various jobs for which you
are responsible. To make an accurate estimate of the
5. Keep track of the work as it is being done. In time required to complete a specific repair job, you must
particular, check to be sure that proper materials and also consider what part of the work must be done by
parts are being used, that the job is properly laid out or other shops and what kinds of interruptions and delays
set up, that all tools and equipment are being used that may occur. Although these factors are also
correctly, and that all safety precautions are being important in the routine scheduling of maintenance and
observed. repair work, they are particularly important when
6. After a job has been completed, make a careful estimates of time may affect the operational schedule of
inspection to be sure that everything has been done the ship.
correctly and that all final details have been taken care If part of the job must be done by other shops, you
of. Check to be sure that all necessary records and must consider not only the time actually required by
reports have been prepared. These job inspections serve these shops but also time that may be lost if one of them
at least two important purposes—first, they are needed holds up your work and the time spent to transport the
to make sure that the work has been properly performed; material between shops. Each shop should make a
and second, they provide for an evaluation of the skills separate estimate, and the estimates should be combined
and knowledge of the person who has done the work. to obtain the final estimate. Don’t attempt to estimate
Don’t overlook the training aspects of a job inspection. the time required by other personnel. Attempting to
When your inspection of a completed job reveals any estimate what someone else can do is risky because you

13-22
can’t possibly have enough information to make an commander usually designates the type of inspection
accurate estimate. and when it will be held.
Consider all the interruptions that might cause Your command will usually be notified in advance
delay, over and above the time required for the work when various inspections are to be held. However,
itself. Such things as drills, inspections, field days, and preparations for such inspections should not be
working parties can have quite an effect on the number postponed until notices are received. It is a mistake to
of people who will be available to work on the job at any think that a poorly administered division or department
given time. can, by a sudden burst of energy, be prepared to meet
the inspector’s eagle eye. By using proper procedures
Estimating the number of personnel required for a
and keeping up to date on such items as repair work,
certain repair job is, obviously, closely related to
maintenance work, operating procedures, training of
estimating time. You will have to consider not only the
personnel, engineering casualty control drills,
nature of the job and the number of people available, but
maintenance records, and reports, you will always be
also the maximum number of people who can work
ready for any type of inspection at any time.
effectively on a job or on part of the job at the same time.
Doubling the number of personnel will not cut them time Since your ship may be designated to provide
in half instead, it will result in confusion. personnel to perform an inspection on another
command, you, as a PO1 or CPO, may be assigned the
The best way to estimate the time and the number
duty as an assistant inspector. Therefore, you should
of personnel needed to do a job is to divide the total job
know something about the different types of inspections
into the various phases or steps that will have to be done.
and trials and how they are conducted.
Then, estimate the time and the personnel required for
each step. There are a variety of types of inspections, each with
a specific purpose. Since the Electrician’s Mate rating
Estimating the materials required for a repair job is
is an engineering rating, we will focus on those
often more difficult than estimating the time and labor
inspections which most directly affect the engineering
required for the job. Although your own past experience
department.
will be your best guide for this kind of estimating, a few
general considerations should be noted.
ADMINISTRATIVE INSPECTIONS
1. Keep accurate records of all materials and tools
used in any major repair job. These records serve two Administrative inspections cover administrative
purposes—first, they provide a means of accounting for methods and procedures normally used by the ship.
materials used; and second, they provide a guide for Each inspection is divided into two general
estimating materials that will be required for similar jobs categories—the general administration of the ship as a
in the future. whole and the administration of each department. This
TRAMAN only discusses the engineering department.
2. Before starting any repair job, plan the job
carefully and in detail. Make full use of manufacturers’ The purpose of an administrative inspection is to
technical manuals, blueprints, drawings, and any other determine whether or not the department is being
available information, and find out in advance all the administered within the guidelines established by the
tools and materials that will be required for the standard organization and regulations manual of the
accomplishment of each step of the job. United States Navy, Engineering Department
Organization Manual, and other pertinent instructions.
3. Make a reasonable allowance for waste when
calculating the amount of material you will need.
Inspecting Party

INSPECTIONS It is a routine procedure for one ship to conduct an

inspection of a similar division on another ship. General
Naval ships and shore installations are required to
instructions for conducting the inspection are usually
be inspected to ensure that their operation,
given by the division commander; however, the
administration, and equipment reflects a high standard
selecting and organizing of the inspecting party are done
of readiness. The frequency with which the various
aboard the ship that must conduct the inspection.
types of inspections are held is determined by the CNO,
fleet commanders, and type commanders. As far as any The chief inspector, usually the commanding officer
specific ship is concerned, the cognizant type of the ship, will organize the assisting board. The

13-23
organization of the assisting board, in general preservation of machinery and engineering spaces; the
conformance with the departmental organization of the training of personnel; the assignment of personnel to
ship, is divided into appropriate groups. Eacvh group is watches and duties; the proper posting of operating
headed by an inspector with as many assistant inspectors instructions and safety precautions; the adequacy of
as necessary. Chief petty officers and petty officers first warning signs and guards; the marking and labeling of
class may be assigned as assistant inspectors. lines and valves; and the proper maintenance of
operating logs.
The engineering department inspecting group (or
party) is organized and supervised by the engineer
officer. The manner in which an individual inspection Administrative Inspection Checkoff Lists
is carried out depends to a great extent upon the
knowledge and ability of the members of the group (or Administrative inspection checkoff lists are usually
party). furnished to the ship by the type commander. These lists
are used as an aid for inspecting officers and inspecting
General Inspection of the Ship as a Whole party personnel to assist them in ensuring that no
important item is overlooked. The inspecting
One of the two categories of administrative personnel, however, should not accept these lists as
inspection is the general administration of the ship as a being all-inclusive because additional items develop
whole. Items of this inspection that have a direct that must be considered or observed during an
bearing on the engineering department, and for which inspection. be considered or observed (fig. 13-18).
the report of inspection indicates a grade, are shown
As a petty officer, you should be familiar with the
below:
various checkoff lists used for inspections. These
1. Appearance, bearing, and smartness of checkoff lists will give you a good understanding of how
personnel to prepare for an inspection as well as how to carry out
your daily supervisory duties. You will find it helpful
2. Cleanliness, sanitation, smartness, and
to obtain copies of the various inspection checkoff lists
appearance of the ship as a whole
from the log room and to carefully look them over. They
3. Adequacy and condition of clothing and will give detailed information about what type of
equipment of personnel inspection you may expect for your type of ship.
4. General knowledge of personnel in regard to the The following is an abbreviated sample of an
ship’s organization ship’s orders, and administrative engineering department checkoff list. You should get a
procedures better understanding of the scope and purpose of
5. Dissemination of all necessary information administrative inspections by reviewing this list.
among the personnel
6. Indoctrination of newly reported personnel OPERATIONAL READINESS INSPECTION

7. General education facilities for individuals

The operational readiness inspection is conducted
8. Comfort and conveniences of Living spaces, to ensure that the ship is ready and able to perform the
including adequacy of light, heat, ventilation, and fresh operations which might be required of it in time of war.
water This inspection consists of the conduct of a battle
9. Economy of resources problem and of other operational exercises. A great deal
of emphasis is placed on antiaircraft and surface
Engineering Department Inspection gunnery, damage control, engineering casualty control,
and other appropriate exercises. Various drills are held
The engineering department administrative and observed, and the ship is operated at full power for
inspection is primarily the inspection of the engineering a brief period of time.
department paperwork, including publications, bills, The overall criteria of performance include the
files, books, records, and logs. Additionally, this following questions:
inspection includes other items with which the chief
petty officers and petty officers first class must be 1. Can the ship as a whole carry out its operational
concerned. Some of these items are the cleanliness and functions?

13-24
1. BILLS FOR BOTH PEACE AND WAR

a. Inspect the following, among others, for completeness, correctness, and adequacy.

(1) Department Organization

(2) Watch, Quarter, and Station Bills
(3) Engineering Casualty Bill
(4) Fueling Bill

2. ADMINISTRATION AND EFFECTIVENESS OF TRAINING

a. Administration and effectiveness of training of personnel for current and prospective duties.

(1) Are sufficient nonrated personnel in training to replace anticipated losses?

(2) NAVEDTRA training courses.
(a) Number of personnel enrolled
(b) Percentage of personnel in department enrolled
(c) Number of personnel whose courses are completed

(3) Are personnel concerned familiar with operating instructions and safety precautions? (Question
personnel at random.)
(4) Are personnel concerned properly instructed and trained to handle casualties to machinery?
(5) Are personnel properly instructed and trained in damage control?
(6) Are training films available and used to the maximum extent?
(7) Are training records of personnel adequate and properly maintained?

3. DISSEMINATION OF INFORMATION WITHIN DEPARTMENT

a. Is necessary information disseminated within the department and divisions?

b. Are the means of familiarizing new personnel with department routine orders and regulations
considered satisfactory?

4. ASSIGNMENT OF PERSONNEL TO STATIONS AND WATCHES

a. Are personnel properly assigned to battle stations and watches?

b. Are sufficient personnel aboard at all times to get the ship under way?
c. Are personnel examined and qualified for important watches?
d. Does it appear that personnel on watch have been properly instructed? (Question personnel at
random.)

5. OPERATING INSTRUTIONS, SAFETY PRECAUTIONS, PMS, AND CHECKOFF LISTS

a. Inspect completeness of the following:

(1) Operating instructions posted near machinery

(2) Posting of necessary safety precautions

b. Are PMS schedules properly posted and maintained in the working spaces?
c. Is the Master PMS Schedule posted and up to date?
d. Are responsible personnel familiar with Current instructions regarding routine testing and inspections?
e. Are starting-up and securing sheets properly used?

Figure 13-18.—Engineering inspection checkoff sheet.

13-25
6. PROCEDURES FOR PROCUREMENT, ACCOUNTING, INVENTORY, AND ECONOMY IN USE
OF CONSUMABLE SUPPLIES, REPAIR PARTS, AND EQUIPAGE

a. Is an adequate procedure in use for replacement of repair parts?

b. Are there adequate measures used to prevent excessive waste of consumable supplies?
c. Is there proper supervision in the proper supply of, care of, and accountability for hand tools?
d. Are inventories taken of repair parts which are in the custody of the engineering department?
e. How well are repair parts preserved and stowed?
f. What type of system is used to locate a repair part carried on board? (Have a chief or first class petty
officer explain to you how a repair part for a certain piece of machinery is obtained.)
g. Are custody cards properly maintained for accountable tools and equipment?

7. MAINTENANCE OF RECORDS AND LOGS

a. Inspect the following for compliance with pertinent directives, completeness, and proper form.

(1) Engineering Log

(2) Bell Book
(3) Operating Records
(4) Maintenance Records
(5) Alteration and Installation Program
(6) Daily Oil and Water Records
(7) Engineering Reports
(8) Training Logs and Records
(9) Work Books for Engineering Spaces

8. AVAILABILITY AND CORRECTNESS OF PUBLICATIONS, DIRECTIVES, AND TECHNICAL

REFERENCE MATERIAL

a. Engineering Blueprints Recommended

(1) Ship’s Plan Index (SPI)
(2) Proper indexing of blueprints
(3) Completeness and condition

b. Manufacturers’ Instruction Books

(1) Proper indexing
(2) Completeness and condition

c. Type Commanders Material Letters

d. NAVSEA Technical Manual
e. General Information Book
f. Booklet Plans of Machinery

9. CLEANLINESS AND PRESERVATION

a. Preservation and cleanliness of space (including bilges)

b. Preservation and cleanliness of machinery and equipment
c. Neatness of stowage
d. Condition of ventilation
e. Condition of lighting
f. Compliance with standard painting instructions

Figure 13-18.—Engineering inspection checkoff sheet—Continued.

13-26
 2. Is the ship’s company well trained, well degree of realism of this test determines its value: the
instructed, competent, and skillful in all phases of the more nearly it approximates actual battle conditions, the
evolutions? more valuable it is.

3. Is the ship’s company stationed following the CONDUCT OF A BATTLE PROBLEM.—

ship’s Battle Bill, and does the Battle Bill meet wartime Before a battle problem is conducted, the ship is
requirements? furnished specific information such as that listed below.

Observing Party 1. Authority for conducting the inspection

2. Time of boarding of the inspecting party
The personnel and organization of the operational
readiness observing party are similar to those of the 3. Time the ship is to get under way
administrative inspection party. However, more 4. Time for setting the first material readiness
personnel are usually required for the operational condition
readiness observing party. These additional personnel
are often chief petty officers and first class petty officers. 5. Time for conducting the inspection to zero
problem time conditions
The observing party members are briefed in
advance of the scheduled exercises and drills that are to 6. Zero problem time
be conducted. They must have sufficient training and 7. End of problem time
experience so that they can properly evaluate the
8. Time of critique
exercises and drills that are to be held. Each observer is
usually assigned to a specific station and should be well Observers must be proficient in the proper methods
qualified in the procedure of conducting drills and of introduction of information. In general, when
exercises for that station. That each observer be familiar practical, the information delivered to ship’s personnel
with the type of ship to be inspected is also highly should be verbal and should contain only that
desirable. information which would help the ship’s personnel
develop adequate procedures for the search and
Battle Problems investigation of the imposed casualty. If the ship’s
personnel fail to locate the casualty, the observer may
The primary purpose of a shipboard battle problem resort to coaching, but a notation should be made on the
is to provide a medium for testing and evaluating the observer’s form as to the time allowed before coaching
ability of all divisions of the engineering department to and information were furnished. Special precautions
function together as a team in simulated combat should be taken to give the symptoms of casualty the
operations. same degree of realism that they would have if the
The discussion of the battle problem in this casualty were actual rather than simulated.
TRAMAN is from the viewpoint of the observer and
To impose casualties, ship’s personnel must close
presents some general information about the
valves, open switches, or stop machinery. In each case,
requirements and duties of a member of the engineering
the observer should inform responsible ship’s personnel
department observing party. The knowledge of the
of the action desired, and the ship’s personnel should
viewpoint and duties of an observer should help you
operate the designated equipment.
prepare yourself and your personnel for a battle problem
and other appropriate exercises. NOTE: A casualty should be simulated, or omitted
PREPARATION OF A BATTLE PROBLEM.— entirely, if there is danger that personnel injury or
The degree of perfection achieved in any battle problem material damage might result.
is reflected in the skills and applications of those who
NOTE: The supply of lubricating oil to the main
prepare it. A great deal depends upon the experience of
officers and chief petty officers. The element of surprise engines or the supply of feedwater to the boilers MUST
in the conduct of a battle problem significantly increases NOT be stopped to simulate casualties.
its value.
An emergency procedure should be set up by the
Battle problems are the most profitable and observing party and ship’s company to ensure proper
significant of all peacetime training experience. They action in case actual casualties, as distinguished from
demonstrate a department’s readiness for combat. The simulated or problem casualties, should occur.

13-27
 Although the general amounting system (the 1MC Observers’ Reports.— The observers’ reports are
circuit) may be used by the ship’s company, observers, prepared in the form prescribed by the type commander
normally, have priority in its use. The problem-time and include any additional instructions given by the
announcer uses the general announcing system to chief observer. The reports of the observers are
announce the start of the battle problem, the problem collected by the senior observer for each department and
time at regular intervals, the conclusion of the problem, are submitted to the chief observer. All observers’
and the restoration of casualties. The general reports are reviewed by the senior observers before the
announcing system is kept available at all times for use critique is held.
in case of actual emergency. All other announcing
The observers’ reports (fig. 13-x.—An example of
system circuits and other means of interior
an engineering observer’s report) provide the inspected
communications are reserved for the use of the ship.
ship with detailed observations of the battle problem
Engineering telephone circuits should be monitored which because of time limitations, may not have been
by one or more observers. A check should be made for brought out during the critique. The inspected ship
proper procedure, for circuit discipline, and for proper receives a copy of all observers’ reports; in this way,
handling of information or casualties. each department is given the opportunity to review the
comments and set up a training schedule to cover the
An inspection should be made to see that the
weak points.
engineering plant is properly split following current
directives. Fire hazards, such as paint, rags, or oil; and The blank parts of the observers’ report forms are
missile hazards, such as loose gear, loose floor plates, filled as applicable to the individual observer’s station.
toolboxes; and repair parts boxes should be noted. The Items that were not observed are either left blank or
condition of firefighting, damage control, and crossed out. Additional information, if required for a
remote-control gear should be carefully inspected. certain exercise or condition, may be written on the
reverse side of the form. A separate form or sheet is used
ANALYSIS OF THE BATTLE PROBLEM.—
for each exercise or drill. Remarks or statements made
The maximum benefit obtained from conducting a battle
by the observer should be clear and legible.
problem lies in pinpointing existing weaknesses and
deficiencies and in resulting recommendations for
improvement in organization and training. Every effort MATERIAL INSPECTION
should be made by the observers to emphasize strong
points as well as deficiencies. Knowledge of existing
The purpose of material inspection is to determine
strong points is helpful to boost the morale of the ship’s
the actual material condition of the ship. On the basis
personnel.
of what the inspection discloses, it may be necessary to
Analysis of the battle problem gives the observers recommend repairs, alterations, changes, or
an opportunity to present to the ship’s company their developments that will ensure the material readiness of
opinion of its performance and for the ship’s company the ship to carry out the mission for which it was
to comment on the observers’ remarks as well as to designed. In addition, the material inspection
consider suggested improvements. determines whether or not proper procedures are being
carried out in the care and operation of the machinery
Analysis is conducted in two steps—the critique
and the equipment. Administrative procedures and
and the observers’ report.
material records that are inspected include maintenance
Critique of the Battle Problem.— A critique of the records and routine tests and inspections. The
battle problem is held on board the observed ship before requirements prescribed for material readiness are as
the observing party leaves so the problems and the follows:
actions taken may be reviewed when they are fresh in
1. Established routines for the conduct of
the minds of all concerned. The critique is attended by
inspection sand tests, schedule for preventive
all the ship’s officers, appropriate chief and first class
maintenance, and a system which will ensure timely and
petty officers, the chief observer, and all senior
effective repairs.
observers. The various points of interest of the battle
problem are discussed. The chief observer comments 2. Adequate material maintenance records, kept in
on the overall conduct of the problem after the senior accordance with current directives, that give the history
observers complete their analysis of the battle problem and detailed description of the condition of the
as reported in their observers’ reports. machinery and the equipment.

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Figure 13-19.—Observer’s checklist.

13-29
 3. Planned and effective utilization of the ship’s 4. Any additional instructions considered
facilities for preservation, maintenance, and repair. necessary by the type commander or other higher
authority.
4. Correct allocation of necessary work to the
following categories: Each department must prepare work lists showing
the items of work to be accomplished and the
a. The ship’s force
recommended means for accomplishment (shipyard,
b. The tenders and repair ships tender or repair ship, or ship’s force during an overhaul
or upkeep period). The items are arranged in the
c. The naval shipyards or other shore repair
recommended order of importance and are numbered.
activity
A list of the outstanding alterations is also made up for
The scope of the material inspection is similar to the inspection. Work lists usually consist of 5- by 8-inch
that of the inspection made by the Board of Inspection cards with one repair or alteration item on each card.
and Survey (discussed later in this chapter). These The work list should include all maintenance and repair
inspections should be thorough and searching. They items, because if material deficiencies are found during
should cover in detail, maintenance and repair not the inspection they will be checked against the work
general appearance. The distinction between list. If the item does not appear on the work list, a
administrative inspections and material inspections discrepancy in maintaining the required records will be
should be readily recognized, and there should be as noted by the inspector.
little duplication as possible. Examination of the
material maintenance records and reports should be
Condition Sheets
made to determine the material condition of the
machinery and the equipment. General administrative
methods, general appearance, cleanliness of Condition sheets are made up by the needs of the
compartments, and cleanliness of machinery are not part different material groups. The engineering department
of this inspection, except in cases where they have a is primarily concerned with the machinery, the
direct bearing on material condition. electrical, the damage control, and the hull condition
sheets. Condition sheets contain checkoff sheets and
The composition of the inspecting party for the material data sheets and consist of a large number of
material inspection is similar to that of the pages. Items for data and checkoff purposes are listed
administiative inspection party. for all parts of the ship and for all machinery and
equipment on board ship.
Preparation for the Material Inspection
In advance of the inspection, a preliminary copy of
the condition sheets of the ship to be inspected must be
At an appropriate time before the date of the filled in. Detailed data for the preliminary copy is
inspection, the chief inspector furnishes the ship with obtained from the maintenance records and reports.
advance instructions. These instructions will include
the following information: An entry for any known fault or abnormal condition
of the machinery or equipment is made in the proper
1. A list of machinery and major equipment to be place on the condition sheets. Details and information
opened for inspection. The limit to which a unit of are given, as necessary, to indicate the material
machinery or equipment should be opened is that which condition to the inspecting party. If corrective work is
is necessary to reveal known or probable defects. The required in connection with a unit or space, a reference
units selected to be opened should be representative and, is made to the work list item. Data and information
in case of a multiple-shaft ship, should not disable more requested in the condition sheets should be furnished
than one half of the propulsion units. Proper whenever possible. The preliminary copy, if properly
consideration must be given to the ship’s operational filled out, represents the best estimate of the existing
schedule and safety. material condition of the ship.
2. A list of equipment to be operated. Auxiliary
When the condition sheets have been completed,
machinery such as the anchor windlass, winches, and
they are turned over to the respective members of the
steering gear are normally placed on this list.
inspecting party upon their arrival on board ship.
3. Copies of the condition sheets. These are During the inspection the inspectors fill in the various
checkoff lists which are used for the material inspection. checkoff sections of the condition sheets. These sheets

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are then used to prepare the final inspection report on on the condition sheets for any particular unit of
the condition of the ship. machinery or equipment.
For more detailed information concerning a ship,
you should obtain a copy of the applicable condition Inspection
sheets from the engineering log room.
The inspectors should conduct the inspection
Opening Machinery for Inspection together with the ship’s personnel. No attempt must be
made to follow a predetermined inspection schedule,
The ship will open machinery as previously directed and different units should be inspected as they are made
by the chief inspector to obtain the inspector’s opinion available by the ship’s company. If the ship is prepared
concerning known or probable defects. The for the inspection, there should be no delay between the
information given in Naval Ship’ s Technical Manual, inspection of the different units of machinery. It is not
chapter 090, is used as a guide in opening particular necessary that all machinery of one type be inspected
machinery units. More detailed information on opening simultaneously. Also, its not necessary to complete the
machinery for material inspections is found in the inspection of one space before going to another.
administrative letters of the type commander.
Important items to be covered by the inspection are
A list of machinery, tanks, and major equipment indicated below:.
opened, and the extent of opening, should be supplied
1. All opened machinery and equipment are
to the inspecting party on its arrival. Test reports on
carefully inspected especially where the need of repair
samples of lubricating oil should be furnished to the
work is indicated on the work list.
machinery inspector.
2. Investigations are made to locate any defects, in
Ship’s company should have portable extension
addition to those already known, which may exist in
lights rigged and in readiness for the units of machinery
material condition or design.
opened up for inspection. The lighting of the spare
should be in good order. The inspectors should be 3. Operational tests of machinery and equipment
furnished flashlights, chipping hammers, file scrapers, conducted in accordance with the furnished list.
and similar items. Precision-measuring instruments
4. Electrical equipment is checked to ensure that it
should be readily available.
is not endangered by salt water from hatches, doors, or
ventilation outlets. Possible leaks in piping flanges are
Assembly of Records and Reports
checked.
The material inspection also includes an inspection 5. Equipment in the engineering spaces is
of various material records and reports. These inspected to ensure that it is properly installed and
documents are assembled so as to be readily available maintained.
for inspection. Records must be kept up to date at all
6. Supports and running gear of heavy suspended
times. Check over all records to make sure that they are
material are inspected.
up to date and that nothing has been overlooked. The
individual records should be filled out and maintained 7. Hold-down bolts, plates, and other members of
following current directives. Where applicable, the machinery foundations are inspected. Hammers may be
petty officer in charge of an engineering space should used for sounding, and file scrapers may be used for
check all records or reports that concern the material or removing paint to disclose any condition of metal
the maintenance procedures of that space. corrosion.
8. Condition sheets are checked to see that the
Conduct of the Inspection
inspector, after receiving the reports from the inspectors,
makes up a report on evaluating and grading the
The inspecting group for the engineering
inspection. The chief inspector discusses, with
department should conduct a critical and thorough
appropriate comment, the following items:
inspection of the machinery and equipment under the
responsibility of the department. The condition sheets a. Those conditions requiring remedial action
supplied by the type commander serve as a guide and a which should be brought to the attention of
checkoff list in making the inspection. Appropriate the commanding officer of the ship
remarks, comments, and recommendations are entered inspected and to higher authority

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 b. Those conditions of such excellence that Acceptance Trials and Inspections
their dissemination will be of value to other
ships Trials and inspections are conducted by the Board
of Inspection and Survey on all ships before final
c. Those suggestions or recommendations
acceptance for naval service to determine whether or not
which merit consideration by higher
the contract and authorized changes there to have been
authority
satisfactorily fulfilled. The builder’s trials and
The final smooth report is written up in a detailed acceptance trials are usually conducted before a new
procedure following the type commander’s directives. ship is placed in commission. After commissioning, a
final contract trial is held. Similar inspections are made
BOARD OF INSPECTION AND SURVEY on ships that have been converted to other types. All
INSPECTION (INSURV) material, performance, and design defects and
deficiencies found, either during the trials or as a result
The INSURV is under the administration of the of examination at the completion of trials, are reported
CNO. This board consists of a flag officer, as president, by the Board, together with its recommendations as to
and other senior offficers as required to assist the the responsibility for correction of defects and
president in carrying out the duties of the board. deficiencies. The Board also recommends any changes
Regional boards and subboards are established, as in design which it believes should be made to the ship
necessary, to assist the INSURV in the performance of itself or other ships of its type. These recommendations
its duties. In this chapter, the discussion centers on are made to the Secretary of the Navy.
shipboard inspections made by suboards. These Unless war circumstances prevent it, an acceptance
subboards consist of the chief inspector and 10 or more trial takes place at sea over an established trial course.
members, depending on the type of ship that is to be The tests include full power runs ahead and astern, quick
inspected. reverse, boiler overload, steering, and anchor engine
tests. During the trial, usually the builder’s personnel
Material Inspections Made by the Board operate the ship and its machinery. Ship’s personnel
who are on board to observe the trial carefully inspect
The inspection made by the INSURV is similar to the operation and material condition of machinery and
the material inspection that has just been discussed. In equipment. They note all defects or deficiencies and
fact, the INSURV’s inspection procedures, condition bring them to the attention of the division or engineer
sheets, and reports are used as guidelines in establishing officer so that each item can be discussed with the
directives for the material inspection. The primary appropriate members of the Board of Inspection and
difference is that the material inspections conducted by Survey.
Forces Afloat, usually a sister ship, while the INSURV
inspection is conducted by a specially appointed board. Survey of Ships
This distinction, however, refers only to routine
shipboard material inspection. It must be remembered Survey of a ship is conducted by the Board of
that the Board of Inspection and Survey conducts other Inspection and Survey whenever a ship is deemed by the
types of inspections. CNO to be unfit for further service because of material
condition or obsolescence. The Board after a thorough
Inspections of ships are conducted by the Board of
inspection, renders an opinion to the Secretary of the
Inspection and Survey, when directed by CNO, to
Navy as to whether the ship is fit for further naval
determine their material condition. Their inspection
service or can be made so without excessive cost.
usually takes place four to six months before regular
overhaul. Whenever practical, such inspections are held When the Board believes that the ship is unfit for
sufficiently in advance of a regular overhaul of the ship further naval service, the Board makes appropriate
so as to include in the overhaul all the work recommendations as to the ship’s disposition.
recommended by the Board following the inspection.
Upon the completion of its inspection, the Board reports SHIP TRIALS
the general condition of the ship and its suitability for
further naval service, together with a list of the repairs, There are a number of different types of trials which
alterations, and design changes which, in its opinion, are carried out under specified conditions. A list
should be made. including most of them is given here:

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 1. Builder’s trial extent of any injury, defect, or maladjustment that may
have appeared during the postrepair trial.
2. Acceptance trials
A certain number of naval shipyard personnel, such
3. Final contract trials
as technicians, inspectors, and repairmen, accompany
4. Postrepair trials the ship on a postrepair trial. They check the operation
5. Laying up or preoverhaul trial of machinery that has been overhauled by the yard. If
a unit of machinery does not operate properly, the yard
6. Recommissioning trials technicians carefully inspect it to determine the cause of
7. Standardization trials unsatisfactory operation.

8. Tactical trials
9. Full power trials Full Power and Economy Trials
10. Economy trials
The trials that are considered to be routine ship’s Trials are necessary to test engineering readiness for
trials are numbers 4, 9, and 10 of the above list. war. Except while authorized to disable or partially
Postrepair, full power, and economy trials are the only disable, ships are expected to be able to conduct
ones discussed in this chapter. Information on the other prescribed trials at anytime. Ships normally should be
types of trials can be found in, Naval Ship’s Technical allowed approximately a 2-week period after tender
Manual, chapter 094. overhauls and a 1-month period after shipyard overhaul
to permit final checks, tests, and adjustments of
Postrepair Trial machinery before being called upon to conduct
competitive trials.
The postrepair trial should be made whenever the
Trials are also held from time to time to determine
machinery of a vessel has undergone extensive
machinery efficiency under service conditions, the
overhaul, repair, or alteration, which may affect the
extent, if any, of repairs necessary, the sufficiency of
power or capabilities of the ship or the machinery. A
repairs, and the most economical rate of performance
postrepair trial is usually made when the ship has
under various conditions of service.
completed a routine naval shipyard overhaul period (the
trial is optional whenever machinery has undergone
only partial overhaul or repair). The object of this trial
is to determine whether the work has been satisfactorily Inspections and Tests Before Trials
completed and efficiently performed and if all parts of
the machinery are ready for service.
The full power and the economy trials, as discussed
The postrepair trial should be held as soon as in this chapter, are considered in the nature of
practical after the repair work has been completed, the competitive trials. It is assumed that the ship has been
preliminary dock trial made, and the persons responsible in full operational status for sufficient time to be in a
for the work are satisfied that the machinery is, in all good material condition and to have a well-trained crew.
respects, ready for a full power trial. The conditions of
the trial are largely determined by the character of the Before the full power trial, inspections and tests of
work that has been performed. The trial should be machinery and equipment should be made to ensure that
conducted in such manner as the commanding officer no material item will interfere with the successful
and commander of the shipyard may deem necessary. A operation of the ship at full power. The extent of the
full power trial is not required in cases where repairs inspections and the tests largely depends on the recent
have been slight, and the commanding officer is performance of the ship at high speeds, the material
satisfied that they have been satisfactorily performed condition of the ship, and the time limits imposed by
and can be tested by other means. operational commitments.

Any unsatisfactory conditions found to be beyond Not later than one day before a trial, the engineer
the capacity of the ship’s force should be corrected by officer must report to the commanding officer the
the naval shipyard. When necessary, machinery should condition of the machinery, stating whether or not it is
be opened up and carefully inspected to determine the in proper condition and fit to proceed with the trial.

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General Rules for Trials satisfactory condition. If the machinery’s condition is
found to be unsatisfactory, all defects and deficiencies
During all full power trials and during other should be fully described and recommendations made
machinery trials, the following general rules should be for correcting them.
observed:
Trial Requirements
1. Before a power trial, the machinery should be
thoroughly warmed up; this can be accomplished by
Trial requirements for each ship cover the rpm for
operating at a high fractional power.
full power at various displacements and injection
2. The speed of the engines should be gradually temperatures. They are furnished to commanders and
increased to the speed specified for the trial. units concerned by the CNO Operations Readiness
Division).
3. The machinery should be operated
economically, and designed pressures, temperatures, As far as reports are concerned, full power trials
and number of revolutions must not be exceeded have a 4-hour duration. The usual procedure is to
operate the ship at full power for a sufficient length of
4. The full power trial should not be conducted in
time until all readings are constant, and then start the
shallow water, which is conducive to excessive
official 4-hour trial period Economy trials have a
vibration, loss of speed, and overloading of the
6-hour duration, with a different speed being run at each
propulsion plant.
time a trial is made.
5. If a full power trial should continue beyond the
Once scheduled, trials should be run unless
length originally specified, then all observations should
prevented by such circumstances as the following:
be continued until the trial is finished.
1. Weather conditions which might cause damage
6. The trial should be continuous and without
to the ship
interruption. If a trial at a constant rpm must be
discontinued for any reason, that trial should be 2. Material troubles that force the ship to
considered unsatisfactory and a new start made. discontinue the trial
7. No major changes of the plant setup or 3. Any situation where running or completing the
arrangement should be made during economy trials. trial would endanger human life
If a trial performance is unsatisfactory, the ship
Underway Report Data
concerned will normally be required to hold a retrial of
such character as the type commander may consider
Reports of trials include all the attending
appropriate.
circumstances, to include the following:
The fact that a ship failed to make the required rpm
Ž Draft forward, draft aft, mean draft, and
for any hour during the trial and the amount by which it
corresponding displacement of the ship at the
failed, should be noted in the trial report.
middle of the trial

• The condition of the ship’s bottom Observation of Trials

• The last time the ship was dry-docked When full power trials are scheduled, observing
• The consumption of fuel per hour parties are appointed from another ship whenever
practical. When a ship is scheduled to conduct a trial
• The average speed of the ship through the water while proceeding independently beween ports or under
the other conditions where it is considered impactical
The average revolutions of the propelling engines.
to provide observers from another ship, the ship under
The methods by which the speed was determined should
trial may be directed to appoint the observers.
also be described.
The number of personnel assigned to an observing
Reports should also include tabulations of gauge
party varies according to size and type of ship. The
and thermometer readings of the machinery in use and
duties of the observing party are usually as follows:
the revolutions or strokes of pertinent auxiliaries. The
auxiliaries in use during the trial should be stated. Each 1. The chief observers organize, instruct, and
report should state whether the machinery is in a station the observing party. They check the ship’s draft,

13-34
either at the beginning of the trial or before leaving port; 1. Unless otherwise ordered a full power trial may
supervise the performance of the engine room be started at any time on the date set.
observers; check the taking of counter readings; render 2. The trial should be divided into hourly intervals,
all decisions following current directives; and check and
but readings should be taken and recorded every half
sign the trial reports.
hour. Data are submitted as hourly readings in the trial
2. The assistant chief observers assist the chief report.
observers as directed; supervise the performance of the
3. Fuel expenditures for each hourly interval of the
observers; check the taking of fuel oil soundings and
trial should be determined by the most accurate means
meter readings; and make out the trial reports.
practical, normally by meter readings corrected for
3. Assistant observers take fuel soundings, meter meter error and verified by soundings.
readings, counter readings, the ship’s draft, and collect
4. The appropriate material condition of the ship
all other data that may be required for the trial reports.
should be set during the different trials.
The following items should be accomplished or
5. During all trials, the usual housekeeping and
considered before the trial is started.
auxiliary loads should be maintained. The minimum
1. When requested by the observing party, the ship services provided should include normal operation of
under trial should provide or designate a suitable the distilling plant, air compressor, laundry, galley,
signaling system so that fuel soundings and the readings ventilation systems, elevators (if installed), and
of counters and meters maybe taken simultaneously. generators for light and power under load conditions
2. The ship under trial should furnish the chief similar to those required for normal operations at similar
observer with a written statement of the date of last speeds under the prescribed material condition
undocking and the authorized and actual settings of all 6. All ships fitted with indicators, torsion meters,
main machinery safety devices and dates when last and other devices for measuring shaft or indicated
tested. horsepower should make at least two observations
3. The ship should have its draft, trim, and loading during the fullpower trial to determine the power being
conform to trial requirements. In case a least draft is not developed.
specified, the liquid loading should equal at least 75 7. The chief observer’s report of the trial should
percent of the full load capacity. state whether all rules for the trial have been complied
4. The chief observer should determine draft and with.
trim before and after the trial, verify the amount of fuel There are special forms used for full power and
on board, and correct the amount of time at the economy trial reports. Illustrations of these forms are
beginning of the trial. The draft observer should also not given in this TRAMAN; however, you can obtain
determine the rpm required for the full power trial at the
copies from your log room and, in this way, get an idea
displacement and injection temperature existing at the
of the data and readings that are required for full power
start of the trial.
and economy trials.
5. The observing party should detect and promptly
Trial forms, and such items as tachometers,
correct any errors in recording data, since it is important
stopwatches, and flashlights, should be available to the
that the required data be correct within the limits of
observing party and to the personnel who take the
accuracy of the shipboard instruments.
readings. Any gauges or thermometers, which are
6. The chief observer should instruct members of considered doubtful or defective, should be replaced
the observing party to detect any violation of trial before trials are held. A Quartermaster must check and
instructions, of or of good engineering practice, and then adjust all clocks in the engineering spaces and on the
verify any such report and provide the commanding bridge before any trials are held.
officer a detailed account of each violation.
Careful inspections and tests of equipment and
Manner of Conducting Trials items of machinery must be made that may cause
difficulties during full power operation, since it is
Some of the requirements in regards to the manner possible that unknown defects or conditions may go
of conducting full power and economy trials are as undetected during operation at fractional powers—the
follows: normal operating condition of the ship most of the time.

13-35
 A common practice among many commanding 3. Periodic hearing testing of noise-exposed
officers when making full power trials is first to bring personnel to evaluate program effectiveness
the ship up to a speed of 1 or more knots below the trial
4. Education of all hands in the command’s
run speed of the ship and then turn the control of the
program and their individual responsibilities
speed (except in cases of emergency nature) over to the
engineer officer. The control engine room, under the 5. Strict enforcement of all prescribed
supervision of the engineer officer, brings the speed up occupational noise control and hearing conservation
slowly, depending on the conditions of the plant, until measures including disciplinary action for violators and
the specified speed has been reached. supervisors, as necessary

Responsibilities
NOISE POLLUTION INSPECTIONS

The Secretary of the Navy policy, contained in

Hearing loss problems have been and continue to be
SECNAVINST 5100.1, emphasizes that occupational
a source of concern within the Navy, both ashore and
safety and health are the responsibilities of all
afloat. In the Navy the loss of hearing can occur from
commands. Accordingly, the following actions and
exposure to impulse or blast noise (that is, gunfire,
responsibilities are assigned.
rockets, and so forth) or from continuous or intermittent
sounds such as jet or propeller aircraft, marine engines, NAVAL MEDICAL COMMAND (BUMED).—
boiler equipment operations, and any number of noise The Commander of the Naval Medical Command must
sources associated with industrial activities (such as manage the hearing conservation program and maintain
shipyards). Hearing loss may be temporary and will the program’s currency and effectiveness. It must
disappear after a brief period of nonexposure, or it may provide audiometric support to all military and civilian
become permanent through repeated exposures to personnel who are included in a hearing conservation
intense noise levels. The loss of hearing sensitivity is program, professional and technical assistance to
generally in the higher frequencies of 4,000 to 6,000 commands responsible for assuring that the hearing of
hertz (Hz) with many people sustaining extensive military and civilian personnel is protected, and
impairment before the all important speech range of 500 appropriate professional and technical hearing
to 3,000 Hz is appreciably affected. conservation guidance and assistance to the Chief of
Naval Education and Training (CNET).
The Navy recognized noise pollution to be a
problem and started to combat it through the Hearing It must develop guidelines and issue certifications
Conservation Program. The main purpose of this following 0PNAVINST 6260.2 enclosure for personnel
program is to establish and implement an effective conducting sound level measurements, personnel
occupational noise control and hearing conservation performing hearing conservation audiometry,
program which has as its goal the elimination/ audiometric test chambers, audiometers, and all sound
prevention of hearing loss. level measuring equipment. It must support a research
and development effort in medical aspects of hearing
Hearing Conservation program conservation to ensure existing technology represents
the most advanced state of the art.

Hearing loss associated with exposure to hazardous CHIEF OF NAVAL MATERIAL.— The Chief of
noise and the high cost of compensation claims have Naval Material (CHNAVMAT) must, in coordination
highlighted a significant problem which requires action with CHBUMED, provides technical assistance and
to reduce or eliminate hazardous occupational noise engineering guidance to commands as indicated in
levels. An effective occupational noise control and OPNAVINST 6260.2 and periodically updates to
hearing conservation program will prevent or reduce the maintain currency and effectiveness. Guidance must
exposure of personnel to potentially hazardous noise. ensure consistent and required military capabilities, and
Such programs will incorporate the following elements: that noise abatement is considered, designed, and
engineered into all (both existing and future) ships and
1. Identification of hazardous noise areas and their
aircraft, weapons and weapon systems, equipment,
sources materials, supplies, and facilities which are acquired,
2. Elimination or reduction of noise levels through constructed, or provided through the Naval Material
the use of engineering controls Command; and it must provide appropriate technical

13-36
and engineering control methodology guidance and maintained on personnel placed in the program. Noise
assistance to CNET. levels will be eliminated or reduced through the use of
engineering controls.
THE CHIEF OF NAVAL EDUCATION AND
TRAINING.— The Chief of Naval Education and Personal hearing protective devices will be
Training (CNET) must, with the assistance of provided and used properly by personnel where
CHBUMED and CHNAVMAT, incorporate hearing administrative or engineering controls are infeasible or
conservation and engineering control guidance ineffective. All military and civilian personnel whose
information in the curricula of all appropriate training duties expose them to potentially hazardous noise will
courses. It must provide specialized hearing receive instruction regarding the command
conservation and engineering control training and occupational noise control and hearing conservation
education, as required, and serve as the central source programs, the undesirable effects of noise, the proper
for the collection, publication, and dissemination of use and care of hearing protective devices, and the
information on specialized hearing conservation and necessity of periodic hearing testing. Emphasis will be
engineering control training courses.
placed upon leadership by example as regards the
NAVAL INSPECTOR GENERAL.— The Naval wearing of hearing protective devices. Command
Inspector General (NAVINSGEN) must evaluate policy must be enforced including the initiation of
hearing conservation and engineering control disciplinary measures for repeated failure to comply
procedures during conduct of the Navy’s Occupational with the requirements of the hearing conservation
Safety and Health Inspection Program (NOSHIP) program.
oversight inspections of activities ashore.
ENGINEERING OFFICER.— OPNAVINST
PRESIDENT, BOARD OF INSPECTION AND 6260.2 outlines the shipboard program for hearing
SURVEY.— The President of the Board of Inspection conservation. Although the medical department
and Survey (PRESINSURV) must be directly representative has primary responsibility over this
responsible for oversight inspection aspects of
program, there are elements that the engineer officer
shipboard hearing conservation and engineering control
must monitor and which are subject to periodic review.
compliance. Inspections of fleet units must be
Periodic surveys must be accomplished to properly
incorporated into existing condition inspection
identify those areas within the propulsion spaces that fall
programs.
into the category “Noise Hazardous Area.” These areas
COMMANDER, NAVAL SAFETY CENTER.— must be marked, and personnel tasked with working in
The Commander of the Naval Safety Center these areas must have available to them and use the
(COMNAVSAFECEN) must provide program prescribed aural protective devices. Training and
evaluation, as requested, provide program promotion discussion should emphasize the need for wearing these
through NAVSAFECEN publications, and review devices and should stress the medical elements of
program compliance during the conduct of surveys. hazards to hearing resulting from “nonuse.” The
FLEET COMMANDER IN CHIEF.— Fleet following paragraphs outline the specific actions to be
Commanders in Chief and other major commanders, taken by the engineering officer and subordinates to
commanding officers, and officers in charge must ensure the effectiveness of the command program.
ensure that all Navy areas, work sites, and equipment
The engineering officer will do the following:
under their responsibtity are identified as potentially
hazardous and labeled following OPNAVINST 6260.2 1. Ensure that all newly reporting personnel have
where noise levels are 85 dBA or greater or where received a baseline audiogram and that each individual’s
impulse or impact noise exceeds a peak sound pressure medical record reflects the results of this examination.
level of 140 dB. Where necessary, surveys must be
conducted in compliance with the guidance outlined in 2. Ensure that all engineering department
OPNAVINST 6260.2, enclosure (l). Enclosure (3) of personnel receive an annual reexamination by a medical
OPNAVINST 6260.2 provides a listing of activities activity.
where industrial hygiene assistance may be obtained. 3. Advise the medical department representative,
Where a potential noise hazard has been identified, by memorandum, of personnel by name who are
a hearing conservation program must be instituted working or standing watches in areas determined to be
following OPNAVINST 6260.2, and a roster will be “high noise areas” and defined in OPNAVINST 6260.2.

13-37
 4. Arrange for a noise survey to be taken initially 8. The main propulsion assistant should be
by an industrial or IMA activity, and ensure that surveys designated as the department officer to monitor and
assist the engineer offficer in all elements of the program.
are redone at least annually.
WORK CENTER SUPERVISOR.— As a work
5. Designate “high noise areas” from the survey
center supervisor, you are responsible for ensuring that
and ensure that areas are properly marked or labeled safety signs are posted in your spaces which are high
with prescribed markings. Advise the medical noise areas, that your personnel are trained and
department of areas so designated and of any changes counseled as to the effects of noise pollution, and that
that may occur. they have the proper hearing protection as required for
that area.
6. Issue aural protective devices to all personnel
tasked to work in designated “high noise areas.” These For additional information on the Hearing
Conservation Program, refer to OPNAVINST 6260.2.
devices will be made available through the medical
department for individual fitting and issue. Issue of
these devices will be recorded in the individuals’ SUMMARY
medical records. Now that you have completed this chapter, you have
an idea of just how many inspections and different types
7. Ensure that sufficient training is provided to
of maintenance you will deal with while in the Navy.
operating personnel concerning the hazards and
Remember, most inspections are designed to help you
preventive elements of the program, stressing the use of in your work by pointing out problem areas before they
available protective devices. become major problems.

13-38
 CHAPTER 14

ENGINEERING CASUALTY
CONTROL

The operating efficiency of a ship depends largely CASUALTY PREVENTION

on the ability of the engineering department to continue
Casualty prevention is the most effective phase if
its services both during normal operations and during
casualties. Casualty control is concerned with the casualty control. It concerns the quality of preventive
prevention, minimization, and correction of the effects maintenance on machinery and systems as an effort
of operational and battle casualties. Casualties are used toward counteracting the effects of operational and
in this chapter as defined in Naval Ship’s Technical battle casualties. Proper preventive maintenance
Manual, chapter 079, volume 2. greatIy reduces casualties caused by material failures.
Continuous detailed inspection procedures are
necessary. These inspections are necessary to disclose
LEARNING OBJECTIVES
partially damaged parts that may fail at a critical time
Upon completion of this chapter, you should be able and to eliminate the underlying conditions that cause
to do the following them. Some conditions that can cause failures include
1. Recognize the purpose of casualty control misadjustment, improper lubrication, and corrosion.
training. These conditions are detrimental to machinery and
cause early failure.
2. Identify the purpose of the Engineering
Casualty Control Evaluation Team (ECCET). Casualty prevention requires constant training.
Casualty control training must be a continuous
3. Recognize the purpose and identify the use of
the Engineering Operational Sequencing step-by-step procedure. It should provide for study time
System (EOSS). and refresher drills. Any realistic simulation of
casualties must be preceded by adequate preparation.
4. Identify the casualty control organization. You must impress upon your watch sections the full
5. List the duties and responsibilities of personnel consequences of any error that may be made in handling
within the casualty control organization. real or simulated casualties.
6. Recognize some engineering casualties and Most engineering plant casualties are caused by
identify the procedures for handling them. lack of knowledge of correct procedures on the part of
This chapter contains a discussion about casualty watch station personnel. If a simple problem is allowed
prevention, training, and restoration. These actions to continue, the ship may be disabled. The following
provide a ship with a well-rounded casualty control chart contains the causes of ineffective casualty control
program. and their prevention:

14-1
 In the past, primary emphasis in casualty control Therefore, the drill cards must give the correct
training was placed on speed. Now, with the procedure to be followed by each watch team member;
development and implementation of the Engineering and the procedure should be in the proper sequence for
Operational Casualty Control (EOCC) portion of the the drill. The engineering officer must ensure that
Engineering operational Sequencing System (EOSS), adequate research is done and that each scenario is
there is a more methodical and organized approach to accurate. EOCC, if installed, should be the prime
casualty control. Because the approach is more information source. The main propulsion assistant
methodical and organized, there is an increase in (MPA) should have custody of a master drill card
control, a decrease in plant disablements, and an package. This package should have appropriate copies
increase in overall safety to plants and personnel.
of applicable drill scenarios. It should also include drill
EOCC and EOSS will be discussed in more detail later.
cards for each space.
To ensure maximum engineering department
Planning and scheduling casualty control drills
operational readiness, a ship must be self-sufficient in
should receive equal priority with other training
conducting propulsion plant casualty control drills. The
evolutions conducted during normal working hours.
management required for such drills involves the
When a specified time for the conduct of casualty
establishment of the Engineering Casualty Control
Evaluation Team (ECCET). Preliminary administrative control drills is authorized by the CO, the engineer
support for the training program must also be officer must prepare a drill plan. Careful preplanning
established. and sequencing of events are mandatory.

After the proposed drill plan is approved by the CO,

ENGINEERING CASUALTY CONTROL designated ECCET personnel meet. The meeting is held
EVALUATION TEAM (ECCET) to make sure that all members of the team understand
the procedures and the sequencing of events. In
An ECCET should be developed for each underway
preparing the drill plan, consideration is given to the
watch section. Also, a sufficient number of personnel
following items:
should be assigned to evaluate each watch station during
the drills. General condition of the engineering plant
The engineering officer must ensure the
Machinery and safety devices out of commission
development of an accurate, comprehensive drill
package. It should be adequate to exercise the Length of time set aside for the drill
engineering department in all phases of casualty control
procedures. The drill package should contain a State of training of the watch section
complete file of drill scenarios and drill cards for each Power to be provided to vital circuits
type of casualty that could possibly occur to the
propulsion plant. Scenarios should contain the Within the constraints of these items, three priorities
following information: are considered.

1. Drill title 1. The first priority on drill selection is given to

boiler casualty drills and/or propulsion space fire drills.
2. Scenario number (if assigned)
These drills represent the greatest danger. They involve
3. General description of the casualty the largest number of propulsion plant watch team
personnel.
4. Method of imposing the drill
2. The second priority is given to lube oil system
5. Cause (several causes should be listed if
plausible) casualties. This is because of the inherent danger to
main and auxiliary equipments that these casualties
6. Estimated time of repair (ETR) represent.
7. Cautions to prevent personnel hazards or 3. The third priority is given to other main engine
machinery damage casualties.
8. Any simulations to be used in the drill NOTE: In selecting drills, the engineering officer
The purpose of the drill cards is to give the ECCET must give emphasis to the development of watch team
members ready reference to procedures to be followed. proficiency in handling priority one casualties.

14-2
 Normally, ECCET members arrive on station who man and operate the ships further compounds the
shortly before the drills begin. Team members make problem of developing and maintaining a high level of
sure that communications are established throughout the operator and operating efficiency.
plant. With the officer of the deck’s (OOD’s) The Navy is aware of these problems. Studies have
permission, the drill initiator imposes a casualty been done to evaluate the methods and procedures
according to the drill plan. With regard to safety of presently used in operating complex engineering plants.
personnel and equipment, drills are conducted as The results of these studies have shown that in many
realistically as possible. Simulations are kept to an instances sound operating techniques were not
absolute minimum. Any time a hazardous situation
followed. Some of the problems found in engineering
develops, ECCET members assist the watch section in plants are described in the following paragraphs:
restoring the plant to proper operation. ECCET
members also complete a drill critique form during the The information needed by the watch stander
course of the drill. was scattered throughout publications that were
generally not readily available.
As soon as possible, following the drill, a critique is
conducted. Personnel of the applicable watch section The bulk of the publications were not systems
attend. ECCET members and the engineering officer oriented. Reporting engineering personnel had to learn
also attend. The ECCET leader gives the result of the specific operating procedures from old hands presently
drill. All other ECCET members then read their drill assigned. Such practices could ultimately lead to
critique forms. Drills are evaluated as satisfactory or misinformation or degradation of the transferred
unsatisfactory by the ECCET leader. The evaluation is information. These practices were costly and resulted
based on a review of the critique sheets before the in nonstandard operating procedures, not only between
critique. The following deficiencies form a basis for a adjoining spaces but also between watch sections within
finding of unsatisfactory: the same space.
1. Loss of plant control by the EOOW or space Posted operating instructions did not apply to the
supervisor when either is unaware of overall plant installed equipment. They were conflicting or incorrect.
status. It is also unsatisfactory if they are unable to No procedures were provided for aligning the various
restore the plant to a normal operating condition systems with other systems.
utilizing EOSS/EOCC or other issued casualty control
procedures. The light-off and securing schedules were
prepared by each ship and were not standardized
2. Safety violations that may cause a hazard to between ships. The schedules were written for general,
personnel or result in serious machinery derangement. rather than specific, equipment or system values. They
3. Significant procedural deficiencies that indicate did not include alternatives between all the existing
a lack of knowledge of the proper procedures to be modes of operation.
followed in correcting a casualty. Following these studies, NAVSEA developed the
EOSS, which is designed to help eliminate operational
ENGINEERING OPERATIONAL problems. The EOSS consists of a set of systematic and
SEQUENCING SYSTEM (EOSS) detailed written procedures. The EOSS is made up of
charts, instructions, and diagrams that are developed
The Navy has developed a system known as the specifically for the operational and casualty control
Engineering Operational Sequencing System (EOSS). function of a specific ship’s engineering plant. EOSS
Essentially, the EOSS is to the operation of equipment involves the participation of all personnel from the
as PMS is to maintenance. department head to the watch stander.

In ships of today’s modern Navy, main propulsion EOSS is designed to improve the operational
plants are becoming more technically complex as each readiness of the ship’s engineering plant. It does this by
new class of ship is built and joins the fleet. Increased increasing its operational efficiency and providing
complexity requires increased engineering skills for better engineering plant control. It also reduces
proper operation. Ships that lack the required operational casualties and extends the equipment life by
experienced personnel have material casualties. These (1) defining the levels of control (2) operating within
casualties have jeopardized the ship’s operational the engineering plant, and (3) providing each supervisor
readiness. Rapid turnover of engineering personnel and operator with the information needed. This is done

14-3
by putting it in words they can understand at their watch through operational modes from receiving shore
station. services, to various modes of in-port auxiliary plant
steaming, to underway steaming.
The EOSS is composed of three basic parts.
The EOP documentation is prepared for specifically
1. The User’s Guide
defined operational stages—stages I, II, and III.
2. The Engineering Operational Procedures (EOP)
STAGE I.— Stage I deals with the total engineering
3. The Engineering Operational Casualty Control
plant under the direct responsibility of the plant
(EOCC)
supervisor (EOOW). The EOOW coordinates placing
all systems and components (normally controlled by the
EOSS User’s Guide
various space supervisors) in operation and securing
The User’s Guide is a booklet explaining the EOSS them. This person also supervises functions that affect
conditions internal to the engineering plant, such as
package and how it is used to the ship’s best advantage.
jacking, testing, and spinning main engines. The EOP
The booklet contains document samples and explains
documentation assists the plant supervisor to ensure
how they are used. It provides recommendations for
training the ship’s personnel in using the specified optimum plant operating efficiency, properly
procedures. sequencing of events in each operational evolution, and
the training of newly assigned personnel. During a plant
EOSS documentation is developed using evolution, the EOOW designates control and operation
work-study techniques. All existing methods and of the following systems and components:
procedures for plant operation and casualty control
procedures are documented. These include the actual Systems that interconnect one or more
ship procedures as well as those procedures contained engineering plant machinery spaces and electrical
in available reference sources. The resulting systems
sequencing system provides the best tailored operating
and EOCC procedures available pertaining to a Major components, such as boilers, main
particular ship’s propulsion plant. engines, and electrical generators

Systems and components required to support the

Engineering Operational Procedures
engineering plant or other ship functions, such as
(EOP)
distilling plants, air compressors, fire pumps, and
auxiliaries that are placed in operation or secured in
The operational portion of the EOSS contains all
response to demand upon their services
information necessary for proper operation of a ship’s
engineering plant. It also contains guides for To help the plant supervisor with stage I, the EOP
scheduling, controlling, and directing plant evolutions section contains the following documents:

14-4
 Figure 14-1.-Sample plant procedure chart.

STAGE II.— Stage II deals with the system sequence events, to control the operation of equipment,
component level under supervision of the space to maintain an up-to-date status of the operational
supervisor in each engine room and fireroom and the
condition of the equipment assigned, and to train newly
electrical plant supervisor (electrical load dispatcher).
assigned personnel. To assist the space supervisor in
In stage II, the space supervisor accomplishes the tasks
delegated by the plant supervisor. The EOP this effort, the EOP section provides the following stage
documentation helps the space supervisor to properly II documents:

14-5
 Figure 14-2.-Sample plant status diagram.

STAGE III.— Stage III deals with the system control their operation. This is done by manipulating
component level under the supervision of component required valves, switches, and controls. Stage III
operators. The component operators place equipment documentation includes the following:
in and out of operation, align systems, and monitor and

14-6
 Figure 14-3.—Sample preferred alignment diagrams.

The operational use of EOP documentation is of procedures for controlling single- and multiple-source
primary importance at all levels in controlling, casualties.
supervising, and operating the evolutional functions of
the engineering plant. Casualty prevention is the concern of everyone
on board. Proper personnel training provides adequate
knowledge and experience in effective casualty
Engineering Operational Casualty
prevention. The EOCC manual contains efficient,
Control (EOCC)
technically correct casualty control and prevention
procedures. These procedures relate to all phases of an
The casualty control portion of EOSS contains
engineering plant. The EOCC documents possible
information related to the recognition of casualty
symptoms and their probable causes and effects. In casualties that may be caused by human error, material
addition, the EOCC contains information on preventive failure, or battle. The EOCC manual describes proven
actions to take to prevent a casualty. It also specifies methods for controlling a casualty. It also provides

14-7
 Figure 14-4.-Sample training diagram.

information for preventing further damage to the personnel. The EOCC can also be used as an instrument
component, the system, or the engineering plant. to improve casualty control procedure techniques for all
watch standers. The manual contains documentation to
The EOCC manuals are available to personnel in help engineering personnel develop and maintain
their own machinery space so that they can be used as a maximum proficiency in controlling casualties to the
means of self-indoctrination for newly assigned ship’s propulsion plant.

14-8
 Figure 14-5.—Casualty control board.

Proficiency in EOCC procedures is maintained plant operation. Because it is developed through work
through a well-administered training program. study and is system oriented, the EOSS provides the
basic information for the optimum use of equipment and
Primary training concentrates on the control of systems. It does this by specifying correct procedures
single-source casualties. These are casualties tailored for a specific plant configuration.
that can be caused by the failure or malfunction
The EOSS does not eliminate the need for skilled
of a single component or the failure of piping at
plant operators. No program or system can achieve
a specific point in a system.
such a goal. The EOSS is a tool for better use of
Advanced training concentrates on the control manpower and skills. Although the EOSS is an
of multiple casualties or on conducting a battle excellent tool for training shipboard personnel, it is
problem. primarily a working system for scheduling, controlling,
and directing plant operations and casualty-control
An effective, well-administered EOOW training
procedures.
program must contain, as a minimum, the following
elements:
CASUALTY CORRECTION
Recognition of the symptoms
Casualty correction deals with correcting the effects
Probable causes of operational and battle damage to minimize the effect
of the casualty on the ship’s mobility, offensive
Probable effects
capability, and defensive power. Casualty correction
Preventive actions that may be taken to reduce, consists of actions taken at the time of the casualty to
eliminate, or control casualties prevent further damage to the affected unit and actions
taken to prevent the casualty from spreading through
An EOSS package is not intended to be forgotten
secondary effects.
once it is developed and installed aboard a ship. It offers
many advantages to the ship’s operational readiness The speed with which corrective action is applied
capabilities and provides detailed step-by-step to an engineering casualty is often of paramount
sequencing of events for all phases of the engineering importance. The extent of the damage must be

14-9
 Figure 14-6.-Sample component/system alignment diagram.

thoroughly investigated and reported to the engineer The CO has the responsibility of deciding whether
officer. To maintain maximum available speed and to continue operation of equipment under casualty
services, the engineer officer must be informed at all conditions. Such a decision carries the possible risk of
times of the condition of the plant. permanent damage and can be justified only when the

14-10
risk of greater damage or loss of the ship may occur if 5. Keep the OOD and the engineer officer
the affected unit is immediately secured. informed of the condition of the main propulsion plant
and the maximum speed and power available with the
CASUALTY CONTROL ORGANIZATION boiler and machinery combinations that are in use.
6. Ensure that all directives and procedures issued
The speed with which corrective action is applied by higher authority are observed.
depends on how well your casualty control organization 7. Know the power requirements for all possible
is set up and on the amount of training that has been operations. Determine that the boiler and machinery
conducted. combinations in use effectively meet current operational
requirements. Advise the engineer officer and the OOD
Engineering Officer of the Watch (EOOW) when modification of the machinery combinations in
use is considered appropriate. Inform the OOD of any
necessary changes in the operation of boilers, main
The EOOW is the officer on watch in charge of the
engines, generators, and other major auxiliaries.
main propulsion plant and associated auxiliaries. On
most types of ships, the EOOW is normally a senior 8. Supervise the training of the personnel on watch.
petty officer. As an EM1 or EMC, you will be primarily To ensure effective training is held, it is necessary for
responsible for the safe and efficient performance of the the EOOW to understand specific operation and
engineering department watches (except damage maintenance of engineering plant equipment. Refer to
control). The engineer officer determines who is Machinist’s Mate 3 & 2, NAVEDTRA 12144, chapters
qualified to perform the duties of the EOOW, and makes 2, 3, 4, 9, and 10, and Boiler Technician 3 & 2,
his/her recommendation to the CO for final NAVEDTRA 12140, chapters 2, 3, 4, 7, 8, 9, and 10 for
qualification. this information. The EOOW should insist that each
person in charge of an engineering watch station
When the engineer officer considers you qualified carefully instruct the personnel under their charge in
in all respects, you will be assigned to the watch. The specific duties and in the duties of all persons on the
engineer officer or, in his/her absence, the MPA is same watch station.
authorized to direct the EOOW concerning the duties of
the watch when such action is necessary. Other duties 9. Perform such other duties as the engineer officer
you should perform as EOOW are listed as follows: may direct. The EOOW reports to the OOD for changes
in speed and direction of rotation of the main propulsion
1. Make frequent inspections of the machinery shafts and for requirements of standby power and other
(boilers, engines, generators, evaporators, and engineering services anticipated or ordered. The
auxiliaries) in the engineering department to make sure EOOW reports to the engineer officer for technical
that machinery is being operated under current control and matters -affecting the administration of the
instructions. Ensure required logs are properly watch.
maintained, machinery and controls are properly
manned, applicable inspections and tests are being Watch Teams
performed, and all applicable safety precautions are
being observed. The basic organization for engineering casualty
2. Frequently monitor IC circuits to ensure control is the watch team in each main space.
required circuits are proper] y reamed. Ensure circuit Watch teams should be thoroughly organized. Each
discipline is maintained and correct message procedures
person should be assigned duties for watch standing and
and terminology are used.
casualty control for fire, flooding, and setting material
3. Ensure that all orders received from the OOD conditions. The petty officer in charge of each team
concerning the speed and direction of rotation of the should maintain complete control to avoid confusion
main propulsion shafts are promptly and properly that could disrupt organization and coordination of the
executed. Also, ensure the engineering log and the team.
engineer’s bell book are properly maintained.
In effectively controlling engineering casualties, it
4. Immediately execute all emergency orders is extremely important that information be given to all
concerning the speed and direction of rotation of the stations. The engineer officer must receive brief, clear,
main propulsion shafts. and concise information from all stations. This

14-11
information is needed to properly administer the For optimum results, a casualty control board
operation of the engineering plant and to promptly order should be installed at the main engine control, the after
corrective measures for the control of casualties. engine room, and at the main propulsion repair party
station. The 2JV talkers at these stations should be
The sound-powered telephone (circuit 2JV) is the
responsible for maintaining the boards. The status of
principal means of transmitting engineering casualty
machinery is indicated by marking the affected unit with
information. The telephone talker has an important job
a grease pencil on the Plexiglass front of the casualty
and is the key to good communications. If a message is
control board.
not relayed promptly and correctly, it may place the ship
in danger. In battle, the safety of the ship and the crew NOTE: The casualty control board in figure 14-5
depends on how well the talker uses his/her voice and is an example and is not suitable for all ship types.
equipment. Officers and petty officers must be
proficient in using proper engineering terms and Repair Party
phraseology. It isn’t the responsibility of the talker to
decipher, translate, or rephrase improperly transmitted In Manual of Navy Enlisted Manpower and
orders; this is the responsibility of the person issuing the Personnel and Occupational Standards, NAVPERS
order or originating the message. It is the duty of the 18068-D, one of the requirements for an EM1 or EMC
talker to relay messages as given. is to supervise a damage control repair party. Being the
leader, you must be familiar with all the equipment used
Standard wording makes communication easier and its function. You must train your personnel in the
both within and between teams. Standard wording use of the equipment and the functions of the repair
minimizes confusion by reducing the amount of party. The functions that each repair party should be
conversation so that transmissions are easily relayed and capable of making and that are common to all repair
understood. When it is practical, one command should parties is listed as follows:
initiate an entire casualty procedure.
1. Making repairs to electrical and sound-powered
It is much more effective within the team and telephone circuits.
between teams to pass the command
2. Giving first aid and transporting injured
CROSS-CONNECT THE PLANT, or CROSS-CONNECT MAIN personnel to battle dressing stations without seriously
FEED, PORT SIDE reducing the damage control capabilities of the repair
than it is to say party.
OPEN VALVES MAIN STEAM 15, MAIN STEAM 8, AUXILIARY 3. Detecting, identifying, and measuring dose and
STEAM 79 AND 80, AND AUXILIARY 44. dose-rate intensities from radiological contamination.
If the command from main engine control is They must be able to survey and decontaminate
CROSS-CONNECT MAIN FEED, STARBOARD contaminated personnel and areas, except where
SIDE, the petty officers in charge of No. 1 and No. 2 specifically assigned to another department as in the
firerooms will repeat CROSS-CONNECT MAIN case of nuclear weapons accident/incident.
FEED, STARBOARD SIDE. The crew already 4. Sampling and/or identifying biological or
assigned this procedure will open the correct valves with chemical agents. They must be able to decontaminate
no further command and report back when a job is done. areas and personnel affected as a result of biological or
This is because the engineer officer often has to wait for chemical attack, except where this responsibility is
a report before giving another command. The use of assigned to the medical department.
good talker procedure and standard wording will show
5. Controlling and extinguishing all types of tires.
immediate results.
6. Each party must be organized to evaluate and
correctly report the extent of damage in its area, to
Casualty Control Board
include maintaining the following:
a. Deck plans showing locations and safe
The casualty control board (fig. 14-5) is essential to
routes to NBC decontamination, battle dressing, and
effective casualty control during battle conditions. It
personnel cleaning stations.
furnishes a complete picture of the machinery available
to the engineer officer at general quarters and watch b. A casualty board for visual display of
personnel during normal watches. structural damage.

14-12
 c. A graphic display board showing damage format are recommended to facilitate the recording and
and action taken to correct disrupted or damaged transmittal of damage control information. Use
systems. The use of standard damage control standard damage control symbology, as shown in
symbology and the accompanying preprinted message figures 14-7, 14-8, and 14-9, to write and read message

Figure 14-7.—Navy standard damage control symbology.

14-13
 Figure 14-8.—Navy standard damage control symbology—Continued.

formats, such as those shown in figure 14-10. In Some of the specific functions for which Repair 5 is
reading this message, you should have come up with the responsible in its own assigned area include the
following information: An 8-inch hole, 4 feet up from following:
the deck at frame 38, starboard side of compartment
1. Maintenance of stability and buoyancy.
2-35-0-L.
Members of the repair party must meet the
While techniques of damage control are identical following criteria:
among the repair parties, each repair locker is
responsible for an area of the ship. One of the a. Be stationed so that they can reach all parts
more demanding areas of responsibility is Repair 5, of their assigned area with a minimum
which is responsible for the main engineering spaces. opening of watertight closures.

14-14
 Figure 14-9.—Navy standard damage control symbology—Continued.

b. Be able to repair damage to structures, all flooding, flooding boundaries,

closures, or fittings that are designed corrective measures taken, and effects
to maintain watertight integrity, by on list and trim
shoring, plugging, welding, or caulking
(2) The liquid load status board is to show
bulkheads and decks, resetting valves,
the current status of all fuel and water
and blanking or plugging lines
tanks and the soundings of each tank in
through watertight subdivisions of the
feet and inches.
ship.
2. Maintenance of ship’s propulsion. The
c. Be prepared to sound, drain, pump,
personnel in the repair party must be able to take
counterflood, or shift liquids in tanks, voids,
the following actions:
or other compartments; and be thoroughly
familiar with the location and use of all a. Maintain, repair, or isolate damage to main
equipment and methods of action. propulsion machinery and boilers.

d. Maintain two status boards for accurate b. Operate, repair, isolate, modify, or segregate
evaluation of underwater damage: vital systems.

(1) The stability status board (flooding c. Assist in the operation and repair of the
effects diagram) used to visually display steering control systems.

14-15
 d. Assist in the maintenance and repair of
communications systems.
e. Assist repairs 1, 2, 3, and 4 and the crash and
salvage team when required.

FIREROOM CASUALTIES

The fireroom watch section supervisor

should always notify the EOOW of fireroom
casualties. Engine room action is based on reports
given by the fireroom supervisor. When a
fireroom casualty affects the operation of the engine
room, cooperation and communication between
personnel of both the spaces are extremely
important.
Some of the fireroom casualties that affect
the engine room and the procedures for controlling
them include high water, low water, failure of
forced draft blowers, and loss of fuel oil in
suction.

High Water

If the fireroom casualty high water in the boiler

occurs during split plant operation, the following
procedures should be carried out simultaneously by all
Figure 14-10.—Preprinted message format. watch standers:

14-16
 After the boiler is secured, the fireroom watch use and the speed of the ship is high, the ship will have
should run down the water to the steaming level, relight to be slowed. If only one blower is in use, its failure will
fires, and bring the boiler back on the line. necessitate securing the boiler until another blower can
be started. If there is only one boiler furnishing steam
Low Water
to a space, the MM should cross-connect the space and
take steam from another boiler.
The fireroom casualty low water in boiler also
requires that the affected boiler be secured. It is not
necessary to trip the ship’s service generator as in the Loss of Fuel Oil Suction
case of high water unless the boiler is secured.
However, speed in cross-connecting is important to
The loss of fuel oil suction will cause boiler
maintain steam to the turbines.
burners to sputter, fires to die out, and possible racing
Failure of Forced Draft Blower of the fuel-oil service pump. Upon a loss of fuel oil
suction, the following actions should be
Failure of a forced draft blower can be serious, accomplished:
depending on existing conditions. If two blowers are in

14-17
 After it has been determined that good oil is If the turbine has been standing idle for more than
available, the engineers should carry out the procedure 5 minutes without being spun, it is probable that the rotor
for placing a boiler on the line. The engineers should has been bowed temporarily. Upon restarting the
then investigate and correct the cause of the trouble and turbine, vibration may be evident. If so, a brief slowing
sound the tank to determine the quantity of oil in the of the turbine will usually permit the rotor to straighten.
tank. If the oil is above the suction line, the fuel oil is
contaminated or the suction line is clogged. If the fuel Loss of Lube Oil
oil contains water, the tanks should be sounded or tests
performed to find the source of the contamination.
All personnel should know that even a momentary
ENGINE ROOM CASUALTIES loss of lubricating oil can result in localized overheating
and probable slight wiping of one or more bearings.
The operational engine room casualties that might Such wiping may result in only a momentary rise in the
temperature of the lubricating oil discharged from the
occur include excessive vibration of a shaft, vibration of
a turbine, loss of lube oil, and many others. bearing(s). Damage can be prevented or minimized by
stopping the shaft rotation and quickly restoring the
Excessive Shaft Vibration lubricating oil flow. Continued operation with wiped
bearings can cause serious derangement to the shaft
If a shaft develops excessive vibration, watch packing, oil seals, and blading.
personnel should take the following actions: Upon indication of a loss of lube oil to the main
engine, the following actions should be taken:

The other engine should be speeded up to maintain

speed if the tactical situation requires. If the cause for
the unusual noise is undetermined, inspect the propeller, Loss of lubricating oil pressure may be caused by
fairwaters (sleeves), and rope guards at the first failure of the system itself. This includes failure of the
opportunity. main lubricating oil pumps, failure of steam or electrical
power supply to the main lubricating oil pumps, or
Turbine Vibration damage to boilers, steam lines, or electrical equipment.

Failure of component parts of the lube oil system

If a turbine begins to vibrate, the individuals on
may be caused by the presence of dirt, rags, or other
watch should take the following actions:
foreign matter. This is usually the result of improper
cleaning. Failure of the system may be caused by a
piping failure, a failure of the operating pump, or failure
of the standby pump to start. Standby pumps should be
maintained ready to start the moment the pressure drops
below a prescribed operating value. If automatic
starting devices are not available on steam-driven
pumps, the pumps should be lined up so that opening
the throttle is the only action required. Steam supply
lines to standby pumps should be drained continuously.
Where electrical pumps are installed, personnel should
be thoroughly familiar with alternate sources of power.

14-18
 If steam pressure is lost in one engine room during wearing rubber gloves (use a rubber mat or boots as
split plant operation and the tactical situation permits, additional insulation) to determine the source of trouble
take way off the ship by backing the other engine. and effect repairs.
Determine the nature of the casualty causing the loss of If an electrical fire occurs in a switchboard with a
steam. If a loss of steam pressure in the engine room generator on the line, trip the appropriate circuit
will not cause a loss of steam to the other plant, open the breakers (fig. 14-6). The MM should actuate the
auxiliary and the main steam cross-connections overspeed trip on the generator and notify the EOOW.
immediately. If the damage caused a loss of steam to The EOOW then notifies the OOD and the engineering
the other plant, isolate the damage and then open the officer.
auxiliary and the main steam cross-connections as soon
as possible. Stop and lock the affected shaft as soon as The EM should secure the voltage regulator, trip the
steam is available. bus-tie circuit breaker, and open the feedback circuit
breaker. If the fire is in the forward switchboard, the
ELECTRIC PLANT CASUALTIES EM should notify the after switchboard watch to open
the after bus tie circuit breaker and should then use a
Knowing the maximum operating limits of the
C02 fire extinguisher on the fire. The damaged section
electric plant is of prime importance during casualty
of the switchboard should not be reenergize until
operation. You must know the maximum allowable
repairs have been made.
bearing temperatures, generator winding temperatures,
maximum generator loads, and so forth. If an electrical fire occurs in a generator, the
Supplying vital power during casualty operation generator should be secured immediately. If the fire
may require that generators be operated under overload occurs while operating split plant, the EM should trip
conditions. Assuming that the prime mover can handle the generator circuit breaker for the affected generator
the overload, the temperature of the generator windings and close the bus tie. Use a C02 fire extinguisher on the
is the determining factor during sustained overloads. A fire. If a generator fire occurs during operation with a
portable blower may be used on open-type machines to single generator, the switchboard should be stripped of
keep the winding temperature within safe limits. all nonvital circuits after opening the generator breaker.
The vital circuits should then be supplied from the
Operational electric plant casualties that might
emergent y diesel generator.
occur include loss of generator, electrical fires, loss of
lube oil, and overloaded generator.

Electrical Fires Loss of Lube Oil

The proper procedure in the event of an electrical

Upon failure of generator lube oil pressure, take the
fire is as follows:
following actions:

Do not stand directly in front of the panel that is on

fire. Keep low and to one side while using the CO2
extinguisher. Once the fire is out and the danger of After the turbine has completely stopped,
reflash has passed, the electrician should open the panel investigate and correct the casualty.

14-19
Overloaded Generator reduces arcing at the setup switch contacts. It also
prevents flashover of the generator commutator.
Overload on a generator is reduced by removing
nonvital loads. (NOTE: Power should not be Control Console Casualty
interrupted to vital machinery and circuits unless A casualty to the pilothouse control console or
absolutely necessary.) associated circuitry requires a shift in control of the
Vital machinery and circuits include the steering engines to the engine room station. Perform the
following actions to shift control to the engine room:
gear, IC switchboard, fire pumps, drainage pumps, vital
auxiliaries in the fire and engine rooms, gun mounts, and
navigational lights.

DIESEL ELECTRIC DC DRIVE (FLEET

TUG) CASUALTIES
Operational casualties that may occur to this type of
drive include casualties to any one of the four main
propulsion generators or exciters. It can also occur to
the main propulsion motors, control equipment, and
associated circuits.

Propulsion Generator Casualty

A casualty to one of the main propulsion generators Note that the control transfer switch and the
excitation control switch are interlocked so that the
or exciters requires cutting the affected generator out of
excitation control switch has to be in the OFF position
the series propulsion loop. It is not necessary to turn the
before the control transfer switch can be operated.
speed controller to the STOP position when cutting the
generator into or out of the propulsion circuit. BATTLE CASUALTIES
Normally, the controller should be brought to. a position Shell or torpedo hits in engineering spaces usually
not higher than the 11th (engine operating at 350 rpm). result in multiple casualties to machinery systems and
When it is required, a generator may be cut out of the personnel. The corrective action for any particular
circuit while the engine speed is in excess of 350 rpm. casualty depends on the location and extent of damage.
The generator setup switches are designed for such While battle casualties differ in many respects, the
service. Wait several seconds between the opening of following procedures can be applied to most casualties
the generator’s control switch and its setup switch. This of this type:

14-20
DAMAGED CABLE AND EQUIPMENT Preservation of the watertight integrity of the
In any casualty involving damage to electrical cable ship
and equipment, electrical circuits may be a hazard if Simplicity of installation and operation
they remain energized. The circumstances surrounding
each case of damage will dictate action to be taken. In Flexibility of application
cases of serious damage, remove electrical power, when
Interchangeability of parts and equipment,
necessary, from all cables in the damaged area. This is
minimum weight and space requirements
to prevent the ignition of combustible liquids and gases.
Continued operations, however, may require the The ability to accomplish the desired functions
reestablishment of power to undamaged circuits. This
The casualty power system is a temporary means of
may include cables that extend through damaged areas.
providing power. It is not a means of making temporary
In some cases, splices may be made or temporary repairs. The system is purposely limited in its scope to
jumpers may be run to reestablish power to the required retain effectiveness. The more equipment added and the
circuits. Lighting circuits are not to be disregarded. more the system is expanded, the greater the possibility
This is because damage control activities can be of error in making connections. Also, the possibility of
seriously handicapped or rendered impossible by faults at relatively unimportant equipment can cause
inadequate lighting. loss of power at vital equipment. It is also probable that
Damaged electrical equipment should be isolated the casualty power system, if expanded, would be
from all available sources of power. In the case of a burdened with miscellaneous loads at a time when its
damaged switchboard, all circuits feeding to the use would be essential for vital loads.
switchboard from remote sources should be
The schematic diagram for an electrical casualty
de-energized. They should be tagged out of service at
power system in a typical destroyer is shown in figure
the source.
14-11. The system contains no permanently installed
CASUALTY POWER SYSTEM cables, except for vertical risers and bulkhead terminals.
The casualty power system is limited to minimal The risers are installed to carry circuits through decks
electrical facilities required to keep the ship afloat in the without impairing the watertight integrity of the ship. A
event of damage and to get it out of a danger area. riser consists of a LSTSGU-75 cable extending from
Important features of the casualty power system include one deck to another with a riser terminal connected to
the following: each end for attachment of portable cables.

Figure 14-11.—ElectricaI casualty power system.

14-21
 Portable LSTHOF-42 cables in suitable lengths are located in several strategic positions throughout the
form all the circuits required to supply power to ship for use with the casualty power system.
equipment designated to receive casualty power. While
In general, the casualty power system provides a
the normal current-carrying capacity of LSTHOF-42
horizontal run of portable cable along the damage
cables is 93 amperes, its casualty rating is 200 amperes.
control deck with risers for the power supply and for
Under normal conditions, this cable will carry 200
loads extending to and from this level. Rigging and
amperes for 4 hours without damage to the cable.
unrigging casualty power cables are described in
The bulkhead terminals carry circuits through chapter 3 of this manual.
bulkheads without impairing the watertight integrity of
In figure 14-11, the ship’s service switchboards ( 1S
the ship.
and 2S) and the emergency switchboards (1E and 2E)
Power panels supplying equipment designated for are provided with casualty power terminals installed on
casualty power service are equipped with terminals so the back of the switchboard. Each casualty power
that casualty power can be fed into the panels. These terminal is connected to the buses through a standard
panels can also be used as a source of power for the 250-ampere AQB circuit breaker. The circuit breakers
casualty power system if power is still available from have an instantaneous (magnetic) trip element setting to
the permanent feeders to the panels. However, the prevent tripping of the generator breaker or fusing of the
decision to take power from the panel instead of the casualty power cable under short-circuit conditions.
switchboard should be based on knowledge that Connections to the buses are between the generator
equipment on that panel will not be required for the circuit breaker and the disconnect switch.
safety of the ship. Operating the equipment normally
MARINE GAS TURBINE CASUALTIES
supplied by the panel plus the equipment to be supplied
with casualty power may cause an overload on the Normally, any casualty to a marine gas turbine unit
circuit breaker supplying the panel. Portable switches will require that the unit be secured. Therefore, you

Figure 14-12.—Normal stop modes.

14-22
 Figure 14-13.—Emergency stop modes.

need to know the casualty control procedures for marine out-of-limits parameter may be sensed by either the
gas turbine casualties. In this section, you will learn control system or b y the operator. If the control system
some of the procedures for securing a gas turbine senses an out-of-limits parameter, electronic logic
engine. The three most common methods for securing causes the engine to stop. If the operator senses the
gas turbine engines are (1) normal stop (normal out-of-limits parameter, the operator should manually
5-minute cool down and stabilization period), (2) stop the gas turbine by using the manual emergency stop
emergency stop (operator or logic initiated by hazardous switches.
out-of-limits parameter), and (3) fire stop (operator- or NOTE: Certain logic stop functions may be
logic-sensed fire). disabled if battle override is on.
Normal Stop Mode
Fire Stop Mode
The normal stop mode is the most common method
The fire stop mode is used when a fire is detected
used to stop a gas turbine. Referring to figure 14-12,
inside the gas turbine module (GTM). Figure 14-14
you can see that there are three submodes to the normal shows the two methods by which the fire stop mode may
stop: be used.
1. Manual—refers to the actual operator-induced
ac tio ns
2. Initiate—refers to the STOP initiate PUSH
BUTTON on the STAR/STOP panel of the
operating console
3. Logic—refers to the electronic logic as
Programmed into the control console
Emergency Stop Mode
The emergency stop mode (fig. 14-13) is the most
commonly used method to stop a gas turbine when a
hazardous, out-of-limits parameter is sensed. An Figure 14-14.—Fire stop modes.

14-23
 1. In the manual submode the operator can GAS TURBINE GENERATOR
manually activate the fire stop and thereby stop CASUALTIES
the GTM when a fire is detected.
2. In the logic submode the system electronics Procedures for handling generator casualties among
activates the fire stop sequence once it detects a different types of ships differ because of differences in
fire. their prime movers. The following casualties are
representative of the types you might find when working
NOTE: The fire stop sequence is disabled when the with gas turbine generators. When there is a difference
system is in battle override. in procedures, you must follow the EOSS/EOP for your
command.
Regardless of which mode is used to stop a gas
turbine engine, the EOOW/CCS must be notified
immediately when any casualty to equipment in the Unusual Noise or Vibration in the Gas Turbine
engineering spaces occurs. Quick, clear Generator
communications among the watch station are the best
defense to avoiding turning any situation from bad to Any unusual noise or vibration in the gas turbine
worse. generator (GTG) must be investigated immediately, An
untended condition could cause further damage or
Some of the casualties that can affect gas turbine
complete loss of a unit that has only needed minor
systems are very closely related to those of ships with
repairs.
different propulsion and power generating systems.
Some of those casualties are listed in the following Once unusual noise or vibration is reported, the
paragraphs. following steps should be taken:

14-24
 Once all procedures have been carried out and the Once the cause has been identified and corrected,
reason for the casualty has been identified and corrected, the unit should be tested according to your ship’s EOP.
start and test the affected GTG according to your local
EOP. PROPULSION GAS TURBINE CASUALTIES
Class B Fire in the Gas Turbine
Generator Module Propulsion gas turbine casualties are treated in
much the same as casualties to the GTG.
When a class B fire is discovered in the GTG
module, the following actions should be taken: Excessive Vibration

Excessive vibration can be caused by a number of

things, including internal part failure, misalignment,
faulty turbine mounts, or bent high speed coupling shaft.

Once excessive vibration is indicated, the following

actions should be taken:

Quick action on the part of watch standers can avoid

the loss of the GTG and prevent reduced electrical
capability.
Loss of Lube Oil Pressure to the Gas
Turbine Generator
A loss of lubricating oil is one of the most serious
casualties that can occur on rotating machinery,
especially machinery that rotates at very high speeds. A
loss of lube oil can be indicated by the following:
1. Below normal lube oil pressure to bearings
2. Audible and/or visual low lube oil pressure
alarm
3. High bearing temperature alarm
Once a loss of lube oil casualty has occurred, the
following actions should be taken:

Once the cause for vibration has been identified and

corrected, start the engine according to your EOP for
testing.

High Lube Oil Temperature

High lube oil temperature can lead to a lubrication

breakdown within the engine, which can result in fire.
Immediate steps to be taken once high lube oil
temperature is indicated include the following:

14-25
 Once the cause for the loss of lube oil has been
determined and corrected, the rotating elements should
be inspected for damage caused by lack of lubrication.
Once all parts have been inspected and/or replaced, start
the engine according to your EOP for testing.

Class B Fire in the Gas Turbine Module

A class B fire in an engineering space is the most

dangerous condition. Since there is no time for delay,
training is essential to minimize danger to personnel and
equipment. Once a class B fire is detected, the
following steps should take place automatically:

Once the problem has been identified and corrected,

use your EOP to light off the engine and test for proper
operation.

Loss of Lube Oil

A loss of lube oil to a gas turbine engine can cause

the same type of damage whether the engine is used for
generating electricity or propulsion. The rotating parts
of the engine must be kept lubricated. When a loss of
lube oil is indicated, the following actions should be
taken:

14-26
 Once repairs are completed the unit must be tested The EOSS, EOP, and EOCC will take you a
extensively using your ship’s EOP. long way in correcting any casualties you might
sustain. Your ECCET should include your
SUMMARY very best personnel so they can pass along their
knowledge to others. As has been stated in the past,
You must remember that a casualty control program
is only as good as you make it. The key word is “the more you sweat in peace, the less you bleed in
“training.” war!”.

14-27
 APPENDIX I

GLOSSARY

A AVERAGE VALUE OF AC— The average of all the

instantaneous values of one-half cycle of ac.
AFTER STEERING CONTROL UNIT— A rudder
command generator that electrically controls B
rudder angle.
BATTERY— A device for converting chemical energy
AIR-CORE TRANSFORMER— A transformer into electrical energy.
composed of two or more coils, which are
wound around a nonmetallic core. BATTERY CAPACITY— The amount of energy
available from a battery. Battery capacity is
AMMETER— An instrument for measuring the expressed in ampere-hours.
amount of electron flow in amperes.
BIMETALLIC ELEMENT— Two strips of dissimilar
AMPERE (A)— The basic unit of electrical current. metals bonded together so a change of
1 volt across 1 ohm of resistance causes a temperature will be reflected in the bending of
current flow of 1 ampere. the element.

AMPLIFIEIR, FLUID— A fluidic element that BURNISHING TOOL— A tool used to clean and
enables a flow or pressure to be controlled by polish contacts on a relay.
one or more input signals that are of a lower
pressure or flow value than the fluid being C
controlled.
CAPACITIVE REACTANCE— The opposition to the
ANODE— A positive electrode of an electrochemical flow of an alternating current caused by the
device (such as primary or secondary electric capacitance of a circuit, expressed in ohms and
cell) toward which the negative ions are drawn. identified by the symbol

APPARENT POWER— That power apparently CATHODE— The general term for any negative
available for use in an ac circuit containing a electrode.
reactive element. It is the product of effective
voltage times effective current expressed in CHARGE— Represents electrical energy. A material
voltamperes. It must be multiplied by the power having an excess of electrons is said to have
factor to obtain true power available. negative charge. A material having an absence
of electrons is said to have a positive charge.
ARMATURE— In a relay, the movable portion of the
relay. CIRCUIT— The complete path of an electric current.

AUTOMATIC BUS TRANSFER (ABT) CIRCULAR MIL— An area equal to that of a circle
SWITCH— Normal and alternate power sources with a diameter of 0.001 inch. It is used for
are provided to vital loads. These power measuring the cross-sectional area of wires.
sources are supplied from separate switchboards
through separated cable runs. Upon loss of the CONDUCTANCE— The ability of a material to
normal power supply, the ABT automatically conduct or carry an electric current. It is the
disconnects this source and switches the load to reciprocal of the resistance of the material, and
the alternate source. is expressed in mhos or siemens.

AI-1
CONDUCTIVITY— Ease with which a substance electrons spin in one direction than another, the
transmits electricity. atom is magnetized.

CONDUCTOR— (1) A material with a large number DROOP— Mode of governor operation normally
of free electrons. (2) A material that easily used only for paralleling with shore power.
permits electric current to flow. Since shore power is an infinite bus (fixed
frequency, droop mode is necessary to control
C O U L O M B — A measure of the quantity of the load carried by the generator. If a
electricity. One coulomb is equal to 6.28 x 1018 generator is paralleled with shore power and
electrons. one attempts to operate in isochronous mode
instead of droop mode, the generator governor
COULOMB’S LAW— Also called the law of electric speed reference can never be satisfied because
charges or the law of electrostatic attraction. the generator frequency is being held constant
Coulomb’s Law states that charged bodies by the infinite bus. If the generator governor
attract or repel each other with a force that is speed reference is above the shore power
directly proportional to the product of their frequency, the load carried by the generator will
individual charges and inversely proportional to increase beyond capacity (overload) in an effort
the square of the distance between them. to raise the shore power frequency. If the speed
reference is below the shore power frequency,
CPR— Cardio-pulmonary resuscitation. the load will decrease and reverse (reverse
power) in an effort to lower the shore power
CROSS-SECTIONAL AREA— The area of a “slice” frequency. The resulting overload or reverse
power will trip the generator breaker.
of an object. When applied to electrical
conductors it is usually expressed in circular
mils. DRY CELL— An electrical cell in which the
electrolyte is in the form of a paste.
CURRENT— The drift of electrons past a reference
E
point. The passage of electrons through a
conductor. Measured in amperes.
EDDY CURRENT— Induced circulating currents in
D a conducting material that are caused by a
varying magnetic field.
D A M P I N G — The process of smoothing out
oscillations. In a meter, damping is used to EDDY CURRENT LOSS— Losses caused by random
keep the pointer of the meter from overshooting current flowing in the core of a transformer.
the correct reading. Power is lost in the form of heat.

D’ARSONVAL METER MOVEMENT— A name EFFICIENCY— The ratio of output power to input
used for the permanent-magnet moving-coil power, generally expressed as a percentage.
movement used in most meters.
ELECTRIC CURRENT— The flow of electrons.
DIELECTRIC FIELD— The space between around
charged bodies in which their influence is felt. ELECTRIC PLANT CONTROL CONSOLE
Also called Electric Field of Force or an (EPCC)— Contains the controls and indicators
Electrostatic Field. used to remotely operate and monitor the
generators and the electrical distribution system.
DIRECT CURRENT (dc)— An electric current that
flows in one direction only. ELECTRICAL CHARGE— Symbol Q, q. Electric
energy stored on or in an object. The negative
DOMAIN THEORY— A theory of magnetism based charge is caused by an excess of electrons; the
on the electron-spin principle. Spinning. positive charge is caused by a deficiency of
electrons have a magnetic field. If more electrons.

AI-2
ELECTROCHEMIC— The action of converting ELEMENT— A substance, in chemistry, that cannot
chemical energy into electrical energy. be divided into simpler substances by any means
ordinarily available.
ELECTRODE— The terminal at which electricity
passes from one medium into another, such as F
in an electrical cell where the current leaves or
returns to the electrolyte. FERROMAGNETIC MATERIAL— A highly
magnetic material, such as iron, cobalt, nickel,
ELECTRODYNAMICS METER MOVEMENT— A or alloys, that makes up these materials.
meter movement using freed field coils and
moving coil; usually used in wattmeters. FIELD OF FORCE— A term used to describe the
total force exerted by an action-at-a-distance
ELECTROLYTE— A solution of a substance that is phenomenon such as gravity upon matter,
capable of conducting electricity. An electrolyte electric charges acting upon electric charges,
may be in the form of either a liquid or a paste. magnetic forces acting upon other magnets or
magnetic materials.
ELECTROMAGNET—An electrically excited
magnet capable of exerting mechanical force, or FIXED RESISTOR— A resistor having a definite
of performing mechanical work. resistance value that cannot be adjusted.

ELECTROMAGNETIC— The term describing the FLUX— In electrical or electromagnetic devices, a

relationship between electricity and magnetism. general term used to designate collectively all
Having both magnetic and electric properties. the electric or magnetic lines of force in a
region.
ELECTROMAGNETIC INDUCTION— T h e
production of a voltage in a coil due to a change FLUX DENSITY— The number of magnetic lines of
in the number of magnetic lines of force (flux force passing through a given area.
linkages) passing through the coil.
FREQUENCY METER— A meter used to measure
ELECTROMOTIVE FORCE (EMF)— The force that the frequency of an ac signal.
causes electricity to flow between two points
with different electrical charges or when there is G
a difference of potential between the two points.
The unit of measurement in volts. GALVANOMETER— A meter used to measure small
values of current by electromagnetic or
ELECTRON— The elementary negative charge that electrodynamics means.
revolves around the nucleus of an atom.
GROUND POTENTIAL— Zero potential with
ELECTRON SHELL— A group of electrons which respect to the ground or earth.
have a common energy level that forms part of
the outer structure (shell) of an atom. H

ELECTROSTATIC— Pertaining to electricity at rest, HENRY (H)— The electromagnetic unit of

such as charges on an object (static electricity). inductance or mutual inductance. The
inductance of a circuit is 1 henry when a current
ELECTROSTATIC METER MOVEMENT— A variation of 1 ampere per second induces 1 volt.
meter movement that uses the electrostatic It is the basic unit of inductance. In radio,
repulsion of two sets of charges plates (one smaller units are used such as the millihenry
freed and the other movable). This meter (mH), which is one-thousandth of a henry (H),
movement reacts to voltage rather than to and the microhenry (µh), which is one-millionth
current and is used to measure high voltage. of a henry.

AI-3
HERTZ (Hz)— A unit of frequency equal to one ISOCHRONOUS— Mode of governor operation
cycle per second. normally used for generator operation. This
mode provides a constant frequency for all load
HORSEPOWER (hp)— The English unit of power, conditions. When operating two or more
equal to work done at the rate of 550 generators in parallel, use of the isochronous
foot-pounds per second. Equal to 746 watts of mode also provides equal load sharing between
electrical power. units.

HOT WIRE METER MOVEMENT— A meter K

movement that uses the expansion of heated
wire to move the pointer of a meter; measures KILO— A prefix meaning one thousand.
dc or ac.
KINETIC ENERGY— Energy that a body possesses
HYDROMETER— An instrument used to measure by virtue of its motion.
specific gravity. In batteries, hydrometers are
used to indicate the state of charge by the KIRCHHOFF’S LAWS— (1) The algebraic sum of
specific gravity of the electrolyte. the currents flowing toward any point in an
electric network is zero. (2) The algebraic sum
HYSTERESIS— The time lag of the magnetic flux in of the products of the current and resistance in
a magnetic material behind the magnetizing each of the conductors in any closed path in a
force producing it, caused by the molecular network is a equal to the algebraic sum of the
friction of the molecules trying to align electromotive forces in the path.
themselves with the magnetic force applied to
the material. L

HYSTERESIS LOSS— The power loss in an LEAD-ACID CELL— A cell in an ordinary storage
iron-core transformer or other ac device as a battery, in which electrodes are grids of lead
result of magnetic hysteresis. containing an active material consisting of
certain lead oxides that change in composition
I during charging and discharging. The electrodes
or plates are immersed in an electrolyte of
INDUCED CURRENT— Current caused by the diluted sulfuric acid.
relative motion between a conductor and a
magnetic field. LINE OF FORCE— A line in an electric or magnetic
field that shows the direction of the force.
INDUCED ELECTROMOTIVE FORCE— The
electromotive force induced in a conductor LOAD— (1) A device through which an electric
caused by the relative motion between a current flows and that changes electrical energy
conductor and a magnetic field. Also called into another form. (2) Power consumed by a
INDUCED VOLTAGE. device or circuit in performing its function.

INDUCTIVE REACTANCE— The opposition to the M

flow ac current caused by the inductance of a
circuit, expressed in ohms and identified by the MAGNETIC FIELD— The space in which a magnetic
symbol force exists.

INSULATION— (1) A material used to prevent the MAGNETIC POLES— The section of a magnetic
leakage of electricity from a conductor and to where the flux lines are concentrated; also
provide mechanical spacing or support to where they enter and leave the magnet.
protect against accidental contact. (2) Use of
material in which current flow is negligible to MAGNETISM— The property possessed by certain
surround or separate a conductor to prevent loss materials by which these materials can exert
of current. mechanical force on neighboring masses of

AI-4
 magnetic material and can cause currents to be a constant potential difference of 1 volt across
induced in conducting bodies moving relative to the resistance will maintain a current flow of 1
the magnetized bodies. ampere through the resistance.

MANUAL BUS TRANSFER (MBT) OHMIC VALUE— Resistance in ohms.

SWITCH— Provides selection between normal
and alternate power sources for selected OHM’S LAW— The current in an electric circuit is
equipment. This transfer switch is used for directly proportional to the electromotive force
controllers with low voltage protection that in the circuit. The most common form of the
requires manual restarting after voltage failure law is E=IR, where E is the electromotive force
and for electronic power distribution panels. or voltage across the circuit, I is the current
flowing in the circuit, and R is the resistance of
MEGA— A prefix meaning one million, also Meg or the circuit.
M.
P
MHO— Unit of conductance; the reciprocal of the
ohm. PARALLAX ERROR— The error in meter readings
that results when you look at a meter from some
MICRO— A prefix meaning one-millionth. position other than directly in line with the
pointer and meter face. A mirror mounted on
MILLI— A prefix meaning one-thousandth. the meter face aids in eliminating parallax error.

MOVING-VANE METER MOVEMENT— A meter PARALLEL CIRCUIT— Two or more electrical

movement that uses the magnetic repulsion of devices connected to the same pair of terminals
the like poles created in two iron vanes by so separate currents flow through each;
current through a coil of wire; most commonly electrons have more than one path to travel
used movement for ac meters. from the negative to the positive terminal.

MULTIMETER— A single meter combining the PERMEABILITY— The measure of the ability of
functions of an ammeter, a voltmeter, and an material to act as a path magnetic lines of force.
ohmmeter.
PHASE— The angular relationship between two
N alternating currents or voltages when the voltage
or current is plotted as a function of time.
NEGATIVE TEMPERATURE COEFFICIENT— The When the two are in phase, the angle is zero,
temperature coefficient expressing the amount and both reach their peak simultaneously.
of reduction in the value of a quantity, such as When out of phase, one will lead or lag the
resistance for each degree of increase in other; at the instant when one is at its peak, the
temperature. other will not be at peak value and (depending
on the phase angle) may differ in polarity as
NEUTRAL— In a normal condition; therefore well as magnitude.
neither positive nor negative. A neutral object
has a normal number of elections. PHASE ANGLE— The number of electrical degrees
of lead or lag between the voltage and current
NONTRIP-FREE CIRCUIT BREAKER— A circuit waveforms in an ac circuit.
breaker that can be held ON during an over
current condition. PHASE DIFFERENCE— The time in electrical
degrees by which one wave leads or lags
O another.

OHM The unit of electrical resistance. It is PHOTOELECTRIC VOLTAGE— A voltage

that value of electrical resistance through which produced by light.

AI-5
PICO— A prefix adopted by the National Bureau of RELUCTANCE— A measure of the opposition that
Standards meaning 10-12. a material offers to magnetic lines of force.

PIEZOELECTRIC EFFECT— The effect of REPULSION— The mechanical force tending to

producing a voltage by placing a stress, either by separate bodies having like electrical charges or
compression, expansion, or twisting, on a crystal like magnetic polarity.
and, conversely, producing a stress in a crystal
by applying a voltage to it. RESIDUAL MAGNETISM— Magnetism remaining
in a substance after removal of the magnetizing
POLARITY— (1) The condition in an electrical force.
circuit by which the direction of the flow of
current can be determined. Usually applied to RETENTIVITY— The ability of a material to retain
batteries and other dc voltages sources. (2) Two its magnetism.
opposite charges, one positive and one negative.
(3) A quality of having two opposite magnetic RHEOSTAT— (1) A resistor whose value can be
poles, one north and the other south. varied. (2) A variable resistor that is used for
the purpose of adjusting the current in a circuit.
P O L A R I Z A T I O N — The effect of hydrogen
surrounding the anode of a cell which increases RLC CIRCUIT— An electrical circuit that has the
the internal resistance of the cell. properties of resistance, inductance, and
capacitance.
POTENTIAL ENERGY— Energy due to the position
of one body with respect to another body or to RMS— Abbreviation of root mean square.
the relative parts of the same body.
ROOT MEAN SQUARE (RMS)— The equivalent
POTENTIOMETER— A three-terminal resistor with heating value of an alternating current or
one or more sliding contacts, which functions as voltage, as compared to a direct current or
an adjustable voltage divider. voltage. It is 0.707 times the peak value of a
sine wave.
POWER— The rate of doing work or the rate of
expending energy. The unit of electrical power ROTARY SWITCH— A multicontact switch with
is the watt. contacts arranged in a circular or semicircular
manner.
P R I M A R Y W I N D I N G — The winding of a
transformer connected to the electrical source. S

R SCHEMATIC CIRCUIT DIAGRAM— A circuit

diagram in which component parts are
RECIPROCAL— The value obtained by dividing the represented by simple, easily drawn symbols.
number 1 by any quantity. May be called a schematic.

RECTIFIER— A device used to convert ac to SCHEMATIC SYMBOLS— Letters, abbreviations, or

pulsating dc. designs used to represent specific characteristics
or components on a schematic diagram.
REFERENCE POINT— A point in a circuit to which
all other points in the circuit are compared. SECONDARY— The output coil of a transformer.

RELAY— An electromagnetic device, with one or S E L F - I N D U C T I O N — The production of a

more sets of contacts, that changes contact counter-electromotive force in a conductor when
position by the magnetic attraction of a coil to its own magnetic field collapses or expands with
an armature. a change in current in the conductor.

AI-6
SENSITIVITY— (1) For an ammeter: the amount of TOLERANCE— (1) The maximum error or variation
current that will cause full-scale deflection of the from the standard permissible in a measuring
meter. (2) For a voltmeter: the ratio of the instrument. (2) A maximum electrical or
voltmeter resistance divided by the full-scale mechanical variation from specifications that can
reading of the meter, expressed in be tolerated without impairing the operation of
ohms-per-volt. a device.

SERIES CIRCUIT— An arrangement where TRANSFORMER— A device composed of two or

electrical devices are connected so that the total more coils, linked by magnetic lines of force,
current must flow through all the devices; used to transfer energy from one circuit to
electrons have one path to travel from the another.
negative terminal to the positive terminal.
TRANSFORMER EFFICIENCY— The ratio of
SERIES PARALLEL CIRCUIT— A circuit that output power to input power, generally
consists of both series and parallel expressed as a percentage.
networks.

SINE WAVE— The curve traced by the projection on

a uniform time scale of the end of a rotating
arm, or vector. Also known as a SINUSOIDAL
WAVE. TRANSFORMER, STEP-DOWN— A transformer so
constructed that the number of turns in
SOLENOID— An electromagnetic device that secondary winding is less than the number of
changes electrical energy into mechanical turns in the primary winding. This construction
motion; based upon the attraction of a movable provides less voltage in the secondary circuit
iron plunger to the core of an electromagnet. than in the primary circuit.

T TRANSFORMER STEP-UP— A transformer so

constructed that the number of turns in the
THERMAL-MAGNETIC TRIP ELEMENT— A secondary winding is more than the number of
single circuit breaker trip element that combines turns in the primary winding. This construction
the action of a thermal and a magnetic trip provides more voltage in the secondary circuit
element. than in the primary circuit.

THERMOCOUPLE— A junction of two dissimilar TRIP-ELEMENT— The part of a circuit breaker that
metals that produces a voltage when heated. senses any overload condition and causes the
circuit breaker to open the circuit.
THERMOCOUPLE METER MOVEMENT— A
meter movement that uses the current induced TRIP-FREE CIRCUIT BREAKER— A circuit
in a thermocouple by the heating of a resistive breaker that will open a circuit even if the
element to measure the current in a circuit; used operating mechanism is held in the ON position.
to measure ac or dc.
TRUE POWER— The power dissipated in the
THETA— The Greek letter used to represent resistance of the circuit, or the power actually
phase angle. used in the circuit.

TIME CONSTANT— (1) The time required to TURN— One complete loop of conductor about a
charge a capacitor to 63.2% maximum voltage core.
or discharge to 36.89% of its final voltage. (2)
The time required for the current in an inductor TURNS RATIO— The ratio of number of turns of
to increase to 63.2% of maximum current of primary winding to the number of turns in the
decay to 36.8% of its final current. secondary winding of a transformer.

AI-7
V of electrical pressure as a current flows through
a resistance.
VOLT— The unit of electromotive force or electrical
pressure. 1 volt is the pressure required to send W
1 ampere of current through a resistance of 1
ohm. WATT— The practical unit of electrical power. It is
the amount of power used when 1 ampere of dc
V O L T A G E — (1) The term used to signify flows through a resistance of 1 ohm.
electrical pressure. Voltage is a force
that causes current to flow through an WATTAGE RATING— A rating expressing the
electrical conductor. (2) The voltage of a maximum power that a device can safety handle.
circuit is the greatest effective difference of
potential between any two conductors of the WATT-HOUR— A practical unit of electrical energy
circuit. equal to 1 watt of power for 1 hour.

VOLTAGE DIVIDER— A series circuit in which WEBER’S THEORY— A theory of magnetism that
desired portions of the source voltage may be assumes that all magnetic material is composed
tapped off for use in equipment. of many tiny magnets. A piece of magnetic
material that is magnetized has all of the tiny
VOLTAGE DROP— The difference in voltage magnets aligned so that the north pole of each
between two points. It is the result of the loss magnet points in one direction.

AI-8
 APPENDIX II

REFERENCES USED TO
DEVELOP THIS NRTC
NOTE: Although the following references were current when
this NRTC was published, their continued currency cannot be
assured. When consulting these references, keep in mind that
they may have been revised to reflect new technology, revised
methods, practices, or procedures. Therefore, you need to ensure
that you are studying the latest references.

Air Conditioning Plant, 80-Ton Capacity, NAVSEA 0959-LP-049-8010, Naval

Sea Systems Command, Washington, DC, Oct 1985. (Chapter 5)

Bibliography for Advancement Study, NAVEDTRA 12052, Naval Education

and Training Program Management Support Activity, Pensacola, FL,
1995. (Chapter 1)

Blueprint Reading and Sketching, NAVEDTRA 14040, Naval Education and

Training Professional Development and Technology Center, Pensacola,
FL, May 1994. (Chapter 2)

Cable Comparison Guide, NAVSEA 0981-LP-052-8090, Naval Sea Systems

Command, Washington, DC, Feb 1975. (Chapter 3)

Cable Comparison Handbook, MIL-HDBK-299(SH), Naval Sea Systems

Command, Washington, DC, Apr 1989. (Chapter 3)

Commutator/Slip Ring Maintenance Handbook, NAVSEA S9310-AC-HBK-

010, Naval Sea Systems Command, Washington, DC, May 1988, Ch. A.
(Chapter 7)

Deep Fat Fyer, NAVSEA 0943-LP-115-8010, Naval Sea Systems Command,

Washington, DC, May 1977. (Chapter 5)

Electrical Machinery Repair, NAVSEA 0900-LP-060-2010, Naval Sea Systems

Command, Washington, DC, Sep 1985, Ch. A. (Chapter 7)

Electric Plant Installation Standard Methods for Surface Ships and Submarines,
DOD-STD-2003-1(NAVY), Naval Sea Systems Command, Washington,
DC, Jun 1987. (Chapter 3,)

Electronic Installation and Maintenance Handbook (EIMB), NAVSEA SE000-

00-EIM-100, Naval Sea Systems Command, Washington, DC, Apr 1983.
(Chapters 2 and 3)

Electrostatic Precipitator Model 430350, Naval Sea Systems Command

Washington, DC, Oct 1981. (Chapter 5)

Fathom, Fall 1984, Safety Poster. (Chapter 1)

AII-1
Fathom, Fall 1987, Safety Poster. (Chapter 1)

Fathom, Spring 1988, Electric Workbench Information. (Chapter 1)

Fathom, Oct/Nov 1989, Safety Poster. (Chapter 1)

Fathom, Sep/Oct 1991, Safety Poster. (Chapter 1)

Fathom, Jan/Feb 1992, Safety Poster. (Chapter 1)

Fathom, Mar/Apr 1992, Safety Poster; Shorting Probe Information.

(Chapter 1)

Fathom, Nov/Dec 1992, Safety Poster. (Chapter 1)

Gas Turbine System Technician (Electrical) 3 & 2, NAVEDTRA 14112,

Naval Education and Training Professional Development and Technology
Center, Pensacola, FL, Dec 1988. (Chapter 3)

Griddle, Model MG-821, NAVSEA 0910-LP-001-7500, Naval Sea Systems

Command, Washington, DC, Apr 1977. (Chapter 5)

Low Pressure Air Compressor Model NAXI 100-3, NAVSEA S6220-C4-

MMO-010, Naval Sea Systems Command, Washington, DC, Feb 1984.
(Chapter 5)

Mark II Basic Brushless Torsionmeter System, SN521-AD-MMA-010, Naval

Sea Systems Command, Washington, DC, May 1994, Ch. B. (Chapter 5)

M-Series Convection Oven, NAVSEA 0934-LP-101-6010, Naval Sea Systems

Command, Washington, DC, Apr 1978. (Chapter 5)

Naval Ships’ Technical Manual (NSTM), S9086-CN-STM-030, Chapter 079,

Vol. 3, “Engineering Casualty Control,” Naval Sea Systems Command,
Washington, DC, Jun 1993, Ch. C. (Chapter 14)

Naval Ships’ Technical Manual (NSTM), S9086-HN-STM-000, Chapter 244,

“Bearings,” Naval Sea Systems Command, Washington, DC, Dec 1994.
(Chapter 7)

Naval Ships’ Technical Manual (NSTM), S9086-H7-STM-000, Chapter 262,

“Lubricating Oils, Greases, and Hydraulic Fluids and Lubricating
Systems,” Naval Sea Systems Command, Washington, DC, Nov 1994.
(Chapter 7)

Naval Ships’ Technical Manual (NSTM), S9086-KC-STM-000, Chapter 300,

“Electric Plant General,” Naval Sea Systems Command, Washington, DC,
Feb 1991, Rev. 2. (Chapter 2 through 4, 6, 8, and 10)

Naval Ships’ Technical Manual (NSTM), S9086-KE-STM-000, Chapter 302,

“Electric Motors and Controllers,” Naval Sea Systems Command,
Washington, DC, Nov 1977, Ch. 1. (Chapters 6 and 7)

AII-2
Naval Ships’ Technical Manual (NSTM), S9086-KN-STM-000, Chapter 310,
“Electric Power Generators and Conversion Equipment,” Naval Sea
Systems Command, Washington, DC, Aug 1990. (Chapters 3 and 6)

Naval Ships’ Technical Manual (NSTM), S9086-KR-STM-000, Chapter 313,

“Portable Storage and Dry Batteries: Naval Sea Systems Command,
Washington, DC, Sep 1990. (Chapter 5)

Naval Ships’ Technical Manual (NSTM), S9086-KY-STM-000, Chapter 320,

“Electric Power Distribution Systems,” Naval Sea Systems Command,
Washington, DC, Jul 1991, Ch. 7. (Chapters 3 and 4)

Naval Ships’ Technical Manual (NSTM), S9086-K9-STM-000, Chapter 330,

“Lighting,” Naval Sea Systems Command, Washington, DC, Ott 1992, Ch.
A. (Chapter 2 and 4)

Naval Ships’ Technical Manual (NSTM), S9086-ND-STM-000, Chapter 400,

“Electronics,” Naval Sea Systems Command, Washington, DC, Apr 1981,
Ch. 5. (Chapters 1 and 2)

Naval Ships’ Technical Manual (NSTM), S9086-QN-STM-000, Chapter 475,

“Magnetic Silencing,” Naval Sea Systems Command, Washington, DC,
Mar 1992. (Chapter 10)

Naval Ships’ Technical Manual (NSTM), S9086-N2-STM-000, Chapter 422,

“Navigation and Signal Lights,” Naval Sea Systems Command,
Washington, DC, Sep 1990. (Chapter 4)

Naval Ships’ Technical Manual (NSTM), S9086-Q5-STM-000, Chapter 491,

“Electrical Measuring and Test Instruments,” Naval Sea Systems
Command, Washington, DC, Jul 1979, Ch. 3. (Chapter 3)

Naval Ships’ Technical Manual (NSTM), S9086-TX-STM-000, Chapter 583,

“Boats and Small Craft,” Naval Sea Systems Command, Washington, DC,
Dec 1992. (Chapter 4)

Naval Ships’ Technical Manual (NSTM), S9086-VF-STM-000, Chapter 633,

“Cathodic Protection: Naval Sea Systems Command, Washington, DC,
Aug 1992, Ch. A. (Chapter 11)

Naval Ships’ Technical Manual (NSTM), S9086-VG-STM-000, Chapter 634,

“Deck Coverings,” Naval Sea Systems Command, Washington, DC, Apr
1991. (Chapter 2)

Navy Electricity and Electronics Training Series (NEETS), Module 1,

NAVEDTRA 14173, Naval Education and Training Program
Management Support Activity, Pensacola, FL, Feb 1992. (Chapter 3)

AII-3
Navy Electricity and Electronics Training Series (NEETS), Module 4,
NAVEDTRA 14176, Naval Education and Training Program
Management Support Activity, Pensacola, FL, Mar 1992. (Chapter 3)

Navy Electricity and Electronics Training Series (NEETS), Module 5,

NAVEDTRA 14177, Naval Education and Training Program
Management Support Activity, Pensacola, FL, Jan 1994. (Chapter 7)

Navy Electricity and Electronics Training Series (NEETS), Module 7,

NAVEDTRA 14179, Naval Education and Training Program
Management Support Activity, Pensacola, FL, Jul 1992. (Chapters 6
and 8)

Navy Electricity and Electronics Training Series (NEETS), Module 13,

NAVEDTRA 14185, Naval Education and Training Program
Management Support Activity, Pensacola, FL, Apr 1986. (Chapter 6)

Navy Occupational Safety and Health (NAVOSH) Program Manual,

OPNAVINST 5100.23D, Chapter 18, “Hearing Conservation and Noise
Abatement,” Department of the Navy, Office of the Chief of Naval
Operations, Washington, DC, Oct 1994. (Chapter 1)

Navy Safety Precautions for Forces Afloat, OPNAVINST 5100.19C,

Department of the Navy, Office of the Chief of Naval Operations,
Washington, DC, Jan 1994. (Chapter 1)

Ship’s Maintenance and Material Management (3M) Manual, OPNAVINST

4790.4C, Department of the Navy, Office of the Chief of Naval
Operations, Washington, DC, Nov 1994. (Chapter 13)

Ship Steering Control System for DD 963 Class Ship, S9560-AH-MMO-01B,

Naval Sea Systems Command, Washington, DC, Dec 1983. (Chapter 5)

Ship’s Service Motors and Controlled, vol. I of III, NAVSEA 0963-LP-019-

1010, Naval Sea Systems Command, Washington, DC, Oct 1994.
(Chapter 1)

Ship’s Service Motors and Controllers, Vol II of III, NAVSEA 0963-LP-019-

1020, Naval Sea Systems Command, Washington, DC, Jan 1970.
(Chapter 6)

Ship’s Store Refrigeration Plant, NAVSEA 0959-LP-049-7010, Naval Sea

Systems Command, Washington, DC, Oct 1985. (Chapter 5)

Stabilized Glide Slope Indicator (SGSI), Mk 1 Mod O, NAVAIR 51-5B-2,

Naval Air Systems Command, Washington, DC, Jan 1979. (Chapter 12)

Standard First Aid Training Course, NAVEDTRA 12081, Naval Education and
Training Program Management Support Activity, Pensacola, FL, Sep
1991. (Chapter 1)

Standard Organizations and Regulations of the U.S. Navy, OPNAVINST

3120.32C, Department of the Navy, Office of the Chief of Naval
Operations, Washington, DC, Apr 1994. (Chapter 1 and 13)

AII-4
Type 24-302-BN-1 Battery Charger-Automatic Vehicle and Boat, NAVSEA
0962-LP-079-5010, Naval Sea Systems Command, Washington, DC, Aug
1974. (Chapter 5)

Ultrasonic Cleaning System, S6200-DT-MMO-010, Naval Sea Systems

Command, Washington, DC, Jun 1981. (Chapter 5)

Visual Landing Aids, Lighting on Air Capable Ships, NAVAIR 51-50ABA-1,

Naval Air Systems Command, Washington, DC, Oct 1973. (Chapter 12)

Washer/Extractor, Model 36021 NSE, NAVSEA 0910-LP-048-0300, Naval Sea

Systems Command, Washington, DC, Jul 1982. (Chapter 5)

Woodward Governor Company Bulletin # 25031-1, The Controlled System,

Woodward Governor Co., Aircraft and Hydraulic Turbine Controls Div.,
P.O. Box 7001, 5001 N. Second St., Rockford, IL, 61101, 1973. (Chapter
9)

Woodward Governor Company Bulletin # 25031-2, Speed Governor

Fundamentals, Woodward Governor Co., Aircraft and Hydraulic Turbine
Controls Div., P.O. Box 7001, 5001 N. Second St., Rockford, IL, 61101,
1973. (Chapter 9)

Woodward Governor Company Bulletin # 25031-3, Parallel Operation of

Alternators, Woodward Governor Co., Aircraft and Hydraulic Turbine
Controls Div., P.O. Box 7001, 5001 N. Second St., Rockford, IL, 61101,
1973. (Chapter 9)

Woodward Governor Company Bulletin # 37705D, EG-M Control Box,

Woodward Governor Co., Aircraft and Hydraulic Turbine Controls Div.,
P.O. Box 7001, 5001 N. Second St., Rockford, IL, 61101, 1964. (Chapter
9)

Woodward Governor Company Bulletin # 37710F, EG-3C and EG-R

Actuators, Woodward Governor Co., Aircraft and Hydraulic Turbine
Controls Div., P.O. Box 7001, 5001 N. Second St., Rockford, IL, 61101,
1969. (Chapter 9)

Woodward Governor Company Bulletin # 37715, EG Load Signal Box,

Woodward Governor Co., Aircraft and Hydraulic Turbine Controls Div.,
P.O. Box 7001, 5001 N. Second St., Rockford, IL, 61101, 1967. (Chapter
9)

Woodward Governor Company Bulletin # 82567F, 2301 120/208V Load &

Speed Sensing Control, Woodward Governor Co., Aircraft and Hydraulic
Turbine Controls Div., P.O. Box 7001, 5001 N. Second St., Rockford, IL,
61101, 1973. (Chapter 9)

Woodward Governor Company Bulletin # 82570C, EG-B2P Governor/

Actuator, Woodward Governor Co., Aircraft and Hydraulic Turbine
Controls Div., P.O. Box 7001, 5001 N. Second St., Rockford, IL, 61101,
1974. (Chapter 9)

AII-5
 APPENDIX III

ELECTRICAL SYMBOLS

AIII-1
AIII-2
AIII-3
AIII-4
AIII-5
AIII-6
AIII-7
 INDEX
A Armatures------Continued Casualty------Continued
stripping of, 7-35 engine room casualties, 14-18
A coil, 10-8
simplex lap windings, 7-28 fireroom casualties, 14-16
AC generators, 3-11 through 3-24
winding armature coils, 7-36 prevention of, 14-1
characteristics of, 3-22
Arms rotation control system, 5-54 Casualty control organization, 14-11
construction of, 3-14
Artificial ventilation, 1-19 engineering officer of the watch, 14-11
frequency of, 3-22
Automatic bus transfer switches, 3-4 repair party, 14-12
operation of, 3-15
Automatic current control, 10-8 watch teams, 14-11
rating of, 3-12
Automatic degaussing systems, types of, Casualty power distribution system, 3-35
revolving armature, 3-11
10-9 through 10-19 rigging casualty power, 3-36
revolving field, 3-12
EMS, 10-15 unrigging casualty power, 3-38
three-phase generators, 3-16
MCD, 10-9 Casualty, prevention of, 14-1
AC motors, 7-21
SSM, 10-15 engineering plant casualties, 14-1
rotors, 7-21
Azimuth, 12-12 Cathodic protection, 11-7 through 11-14
stator coils, 7-21
B impressed circuity protection, 11-6
AC power distribution system, 3-1 through
Circuits, types of
3-38 Battery chargers, types of, 5-7 through 5-9
frequency differency monitoring
400-Hz, 3-34 description of, 5-7
circuit, 8-39
bus transfer switches, 3-4 model 24-302-BN-1, 5-7
reactive droop compensation circuit, 8-26
casualty power distribution system, operation of, 5-8
voltage difference monitoring circuit, 8-42
3-35 specific gravity, 5-2
Circuit breakers, 2-52 through 2-50
circuit markings, 3-2 storage of, 5-1 through 5-7
ACB, 2-42
control equipment, 3-9 Bearings, antifriction, 7-2
ALB, 2-28
ground detector circuits, 3-11 bearing installation, 7-7
AQB, 2-43
phase sequence, 3-3 cleaning ball bearings, 7-5
AQB, A250, 2-44
shore power rigging, 3-39 grease-lubricated ball bearings, 7-4
AQB-LF250, 2-46
shore power unrigging, 3-40 lubrication, 7-3
contact maintenance, 2-49
switchboard, ship’s service, 3-6 oil-lubricated ball bearings, 7-5
NLB, 2-48
transformers polarity marking, 3-34 wear of bearings, 7-3, 7-5
selective tripping, 2-50
AC voltage, 7-21 Bearings, friction, 7-7
Closely regulated power supplies, 8-30
Acid burns, treatment of, 5-7 oil rings and bearing surfaces, 7-8
through 8-35
Actuators, types of trouble analysis, 7-8
Commutators and collector rings, 7-13
EG-R hydraulic actuator, 9-4 Bearings, types of, 7-2
cleaning of, 7-13
hydraulic actuators, 12-11 antifriction bearings, 7-2
truing of, 7-13
Administration, 1-31 through 1-35 friction bearings, 7-7
undercutting mica of commutators, 7-16
coordinated shipboard allowance list Battery chargers, model 24-302-BN-1, 5-7
Contractors, types of, 6-5
(COSAL), 13-18 description of, 5-7
ac contactors, 6-6
maintenance data system, 13-18 operation of, 5-8
dc contactors, 6-5
mandatory turn-n repairable, 7-49 Bleeding, 1-23
Control devices, 2-29 through 2-34
planned maintenance system, 13-15 Blinker lights, 4-28
Controllers, operation of, 6-8
ship’s maintenance and material Board of inspection and survey inspection
low-voltage protection (LVP), 6-8
management systems (ship’s 3-M (INSURV), 13-32
low-voltage release (LVR), 6-8
systems), 13-15 Bridge crane, 5-48
low-voltage release effect (LVRE), 6-8
standard ship organization, 1-31 Brushes, 7-8
Corrosion, 11-1
Air compressors, 5-12 through 5-20 care of, 7-10
cathodic, 11-1
Air coolers, motor and generator, 7-48 seating of, 7-11
Amplifiers Burns, 1-23 D
hydraulic, 9-7 burn emergency treatment, 1-24
DC motors, 7-23
Anchor windlasses, types of, 5-33 through classification of burns, 1-23
armatures, 7-24
5-42 C field coils, 7-24
destroyer, 5-34
Cables, electrical, 2-1 through 2-29 Dimmer control, 12-12
electric, 5-33
cable ends, 2-7 Direct-acting rheostat voltage regulator, 8-4
electric-hydraulic, 5-34
cable maintenance, 2-14 control element, 8-6
Anode system, sacrificial, 11-4
cable markings, 2-12 cross-current compensator, 8-8
sacrificial anodes, types of, 11-4
cable type and size designation, 2-2 damping transformer, 8-7
Antifriction bearings, 7-2
conductor ends, 2-11 operation of, 8-9
cleaning ball bearings, 7-5
conductor identification, 2-11
installation of, 7-7 E
installing cables, 2-7
seized bearings, 7-6
insulation of, 2-15 ECCET, 14-2
Armatures, 7-24
low-smoke cable, 2-2 drill cards, 14-2
hand tools, 7-30
nonflexing service, 2-4 drill card, 14-2
high-potential text, 7-33
radio-frequency coaxial cables, 2-5 EG-M control box, 9-10
insulating materials, 7-31
Cardiopulminary, resuscitation (CPR), EG-R hydraulic actuator, 9-4
lap and wave windings, 7-25
1-19 through 1-21 Engineering plant operations, maintenance,
pitch, 7-26
Casualty and inspections, 13-1 through 13-38
placing coils in slots, 7-37
battle casualties, 14-20 Engineering plant, operation of, 13-1
progressive windings, 7-27
casualty control organization, 14-11 records, 13-2
retrogressive windings, 7-27
correction of, 14-9 responsibilities, 13-1
rewinding of, 7-34
electric plant casualties, 14-19 Electric galley equipment, 5-64 through 5-69

INDEX-1
Electric plant Hazardous materials Motor controllers, types of------Continued
casualties of, 14-19 aerosol dispensers, 1-26 autotransformer, 6-2
electrical fires, 14-19 cathode-ray tubes (CRTs), 1-27 construction of, 6-4
lube oil, loss of, 14-19 cleaning solvents, 1-27 Motor controller, speed selection of, 6-8
Electromechanical action, 11-4 paints and varnishes, 1-26 ac speed, 6-9
resistivity, 11-4 steel wool and emery cloth, 1-27 dc speed, 6-10
stray-current corrosion, 11-4 Hearing conservation program, 1-24 Motors, 7-21
Electrohydraulic load-sensing speed Hearing protective devices, 1-25 ac motors, 7-21
governors, 9-1 through 9-32 Highline and ram tensioner, 5-49 dc motors, 7-23
EG-R hydraulic actuator, 9-4 Hydraulic actuators, 12-11 Motor-generator set, 30-kW, 8-30
hydraulic actuators, 12-11 Hydrometer, 5-3 frequency regulating system, 8-30
Electrohydraulic steering systems, 5-58 voltage regulating system, 8-30
I
through 5-64
Elevators, 5-38 through 5-47 N
Impressed current cathodic protection
Engine room, 14-18 system, 11-6 Navigation lighting, 4-16 through 4-27
Engineering casualty control, 14-1 through cathodic protection log, 11-11 No-break power supply system, 8-34
14-25 components of, 11-7 Noise/vibration analysis, 7-46
casualty correction, 14-9 maintenance of, 11-14 Noise pollution inspections, 13-36
engineering casualty control operation of, 11-11 hearing conservation program, 13-36
evaluation team (ECCET), 14-2 shaft grounding assembly, 11-10
engineering operational casualty Inspections, types of O
control (EOCC), 14-7 administrative, 13-23
Operating records, types of
engineering operational sequencing INSURV, 13-32
Degaussing Folder, 13-13
system (EOSS), 14-3 material, 13-28
Electrical Log, 13-9
Engineering plant operations, maintenance, operational readiness, 13-24
Engineer’s Bell Book, 13-5
and inspections, 13-1 through Incandescent lamps, 4-4
Engineering Log, 13-2
13-38
L Engineering Officer’s Night Order
Engineering plant, operation of, 13-1
Book, 13-10
records, 13-2 Laundry equipment, 5-69 through 5-73 Fuel and Water Reports, 13-7
responsibilities, 13-1 Lighting control panel, 12-18 Gyrocompass Operating Record, 13-10
EOCC, 14-7 Lighting, navigation, 4-16 Monthly Summary, 13-8
casualty prevention, 14-7 Lights Situation Reports, 13-13
training, advanced, 14-9 helicopter in-flight refueling lights Operational readiness inspections, 13-24
training, primary, 14-9 (HIFR), 12-17 battle problem, 13-27
EOSS, 14-3 Light sources
EOP, 14-4 fluorescent lamps, 4-8 P
drill critique, 14-3 glow lamps, 4-11
priorities, 14-2 incandescent lamps, 4-4 Pendulum sensor, 12-12
user’s guide, 14-4 low-pressure sodium lamps, 4-12 pH, 11-3
Engine room, 14-18 Load signal box, 9-12 Planned Maintenance System
parallel operation of, 9-14 cycle schedule, 13-15
F purposes of, 13-15
Logs, 11-11
Feedback control system, 12-4, 12-11 cathodic protection, 11-11 quarterly schedule, 13-15
Fireroom Low-pressure sodium lamps, 4-12 scheduling, 13-17
casualties of, 14-16 LVDT, 12-12 Pressure switch, 12-9
fuel oil suction, loss of, 14-17 Preventive Maintenance System, 13-15
high water, 14-16 M automated ship’s maintenance action
low water, 14-17 Maintenance form, 13-21
Fluorescent lamps, 4-8 preventive maintenance, 13-15 current ship’s maintenance project
Forklift, 5-55 Maintenance and repair of rotating (CSMP), 13-18
Frequency differency monitoring circuit, electrical machinery, 7-1 through cycle schedule, 13-15
8-39 7-49 ship’s maintenance action form, 13-19
Fresnel lens, 12-11 Maintenance data system supplemental form, 13-20
Friction bearings, 7-7 OPNAV 4790/2K 13-19 weekly schedule, 13-17
trouble analysis, 7-8 OPNAV 4790/2L 13-20 Protection, 6-16
G OPNAV 4790/2Q, 13-21 overload protection, 6-16
Material inspection, 13-24 short-circuit, 6-20
2301 electric governor, 9-21
glow lamps, 4-11 condition sheets, 13-30 R
operation of, 9-21 Motor controllers, 6-1
contractors, 6-5 Rating information
Governors, 9-1
enclosures, 6-3 NECs, 1-2
isochronous, 9-1
logic, 6-15 requirements for advancement, 1-1
speed droop, 9-1, 9-19
protective features, 6-16 Refrigeration and air conditioning
Governor/actuator, 9-15
reactor, 6-3 system, 5-20 through 5-26
2301 electric governor, 9-21
reversing, 6-3, 6-11 Rotary amplifier voltage regulator, 8-10
control of, 9-16
size designation, 6-4 amplidyne exciter, 8-11
EGB-2G, 9-15
troubleshooting, 6-23 automatic control unit, 8-12
governor control, 9-18
variable-speed, 6-3 operation of, 8-16
operation of, 9-16
Motor controllers, types of, 6-1 through 6-24 pilot alternator, 8-11
speed droop, 9-19
across-the-line, 6-1 stabilizer, 8-12
H ac primary resistor, 6-2 three-phase response circuit, 8-14
Hand lanterns, 4-38 ac secondary resistor, 6-2 voltage-adjusting unit, 8-12

INDEX-2
Rotating electrical machinery, 7-17 Stabilized glide slope indicator system------ T
ac motors, 7-21 Continued
Test equipment, 1-12
disassembly and reassembly of, helicopter in-flight refueling lights
Three-phase stator rewinding, 7-39
7-17 (HIFR), 12-17
parallel-delta winding, 7-43
rewinding procedures, 7-30 homing beacon, 12-12
parallel-wye winding, 7-42
testing components of, 7-20 hydraulic pump assembly, 12-9
series-delta winding, 7-42
light bar, 12-1
series-wye winding, 7-40
S remote control panel assembly,
Transformers
12-8
connections, 3-29
Safety stabilized platform assembly,
efficiency, 3-28
hearing, 13-36 12-11
motor-driven variable transformer,
portable tools, 1-10 vertical gyroscope, 12-12
12-3, 12-19
rubber gloves, 1-16 wave-off light system, 12-14
polarity markings, 3-34
shock hazards, 1-4 Standard ship organization, 1-31
voltage and current relationships,
shorting probe, 1-10 assistants to the engineer, 1-33
3-26
tag out, 1-29 division leading petty officer, 1-34
ungrounded systems, 1-8 electrical division chief petty officer, U
Ship trials, 13-33 1-34
Ultrasonic cleaner, 5-28
economy, 13-33 electrical (E) division officer, 1-33
full power, 13-33 electrical officer, 1-33 V
postrepair, 13-33 engineering officer, 1-32
engineering operational sequencing Vector analysis, 3-17
Single-phase (split-phase) ac motor
system (EOSS), 14-3 VERTREP lights, 12-18
repair, 7-47
equipment operating logs, 13-1 lighting control panel, 12-18
Slip rings, 7-13
Static converter, 8-33 motor-driven variable transformers,
Small craft electrical system, 5-9
oscillator circuit, 8-33 12-19
through 5-12
phase power control circuit, 8-34 Visual landing aids, 12-1 through 12-21
battery charging system, 5-11
voltage regulators, 8-34 typical VLA installation, 12-2
start motor, 5-9
Static excitation and voltage regulation Voltage and frequency regulation, 8-1
Sources of information
system, 8-18 through 8-44
Navy training manuals, 1-2
automatic operation of, 8-27 Voltage control, principles of ac, 8-1
NEETs modules, 1-2
automatic voltage regulator, 8-22 Voltage differency monitoring circuit, 8-42
technical manuals, 1-3
reactive droop compensation circuit, Voltage regulators, types of, 8-4
SPR-400 line voltage regulator, 8-27
8-26 direct-acting rheostat, 8-4
operation of, 8-27
static exciter, 8-20 rotary amplifier, 8-10
Stabilized glide slope indicator system,
Switches, types of static excitation and voltage
12-1
limit, 2-30 regulation system, 8-18
edge lights, 12-13
pressure, 12-9 SPR-400 line voltage regulator, 8-27
electronic enclosure assembly,
12-4 pressure and temperature, 2-32 W
extended line-up lights, 12-14 solid-state, 6-15
failure detection circuit, 12-1 Synchronizing monitor, 8-35 Wave-off light system, 12-14
glide slope indicator (GSI), phase difference monitoring circuit, Winches, 5-33
12-11 8-37 Window wiper, 5-26
gyro alarm circuit, 12-12 Synchro transmitters, 12-4 Workbench, 1-13

INDEX-3
 ASSIGNMENT 1
Textbook Assignment: “The Electrician’s Mate Rating, General Safety Practices, and Administration,” chapter 1,
pages 1-1 through 1-36.

1-5. If you want to find information about new

Learning Objective: Recognize the developments in shipboard engineering, you
fundamentals of the enlisted rating structure should refer to what publication?
and identify the general requirements for
advancement of active duty and inactive duty 1. Fathom
Electrician’s Mates. 2. Electronics Information Bulletin
3. All Hands
4. Deckplate
1-1. To what rating category do Electrician’s Mates
(EMs) belong?
1-6. To what publication should you refer for
information about the prevention of shipboard
1. Apprenticeship
accidents?
2. Emergency
3. General
1. Military Requirements for Petty Officers
4. Service
3&2
2. Deckplate
1-2. When assigned to shore duty, an EM may
3. Fathom
work outside the rate or rating.
4. All Hands
1. True
1-7. The Navy Electricity and Electronics Training
2. False
Series (NEETS) modules provide what type of
training?
1-3. What is the purpose of assigning an NEC to
EMs?
1. NEETS provides beginners with the
fundamentals of electrical and electronic
1. To identify their specialized skills
concepts
2. To show whether they are eligible to
2. NEETS provides military factors needed
draw proficiency pay
to perform the duties of your rate
3. To identify the types of training for which
3. NEETS provides techniques for installing
they qualify
electrical equipment
4. To indicate the highest types of training
4. NEETS provides the step-by-step
for which they qualify
procedures for conducting casualty
control drills
Learning Objective: Identify the uses of
training publications, technical manuals, and 1-8. Which of the following is a purpose of the
other printed source materials. Electronics Installation and Maintenance Book
(EIMB)?

1-4. If you want to find advanced information on 1. To provide beginners with the
field changes, you should refer to what fundamentals of electrical and electronic
publication? concepts
2. To implement the major policies found in
1. Electronic Information Bulletin NSTM, chapter 10
2. Bibliography for Advancement Study 3. To provide techniques for installing
3. Department of Defense Information electrical equipment
Security Program Regulation 4. To provide step-by-step procedures to
4. All Hands conduct casualty control drills

1
1-9. Which of the following publications will help
you in determining safe practices when
working with electrical and mechanical
equipment?

1. Naval Ship’s Technical Manual (NSTM)

2. Standard Organization and Regulations
of the U.S. Navy, OPNAVINST 3120.32
3. Safety of Precautions for Forces Afloat,
OPNAVINST 5100.19
4. Each of the above

1-10. By observing proper safety precautions, you

will prevent which of the following situations?
Figure 1A.
1. Equipment damage
2. Personal injury IN ANSWERING QUESTION 1-14, REFER TO
3. Both 1 and 2 above FIGURE 1A.
4. Dirty equipment
1-14. What is the potential from B to A?
1-11. Usually, what amount of current is fatal if it
passes through a person’s body for 1 second or 1. 0V
more? 2. Full line voltage
3. One-half of the line voltage
1. 1.0 mA 4. One-half of the phase voltage
2. 0.2 mA
3. 0.1 A 1-15. Shipboard electrical systems are not considered
4. 1.0 A as a perfect ungrounded system. Which of the
following factors makes this statement correct?
1-12. Most shipboard deaths due to electrocution are
caused by shock received from what 1. Generator insulation resistance and
voltage/source? capacitance to ground
2. RFI filter capacitance to ground
1. 450 Vac 3. Cable resistance and capacitance to ground
2. 115 Vac 4. Each of the above
3. 120 Vdc
4. Ungrounded equipment
Learning Objective: Identify requirements for ground
1-13. Final approval to work on an energized connections and recognize precautions regarding the
switchboard is required from which of the repair of circuits, and the use of rubber matting, ground
following persons? straps, and shorting probes.

1. The commanding officer

1-16. When equipment grounding is provided, you
2. The engineering officer
can make sure that the bonding surfaces will
3. The officer of the deck
have a positive metal-to-metal contact by
4. The operations officer
taking which of the following actions?

1. Check the mechanical connection to

ensure proper contact
2. Securely fasten the connection with the
proper mounting hardware
3. Clean the shock mount
4. All of the above

2
 1-20. To discharge capacitors in de-energized
equipment, which of the following devices is
used?

1. A screwdriver
2. A ground strap
3. A shorting probe
4. Each of the above
1-21. What is an acceptable resistance reading for
the ground connection between the ship’s hull
and the metal frame of a portable electric drill?

1. 1 ohm or less
2. 2 ohms
3. 1,000 ohms
4. 1 megohm

1-22. You are inspecting a portable electric drill, and

you notice the cord has exposed conductors.
What action should you take?

1. Replace the plug

2. Replace the cord
Figure 1 B. 3. Patch the cord with tape
4. Cut the damaged section out and splice in
IN ANSWERING QUESTION 1-17, REFER TO a good section of the same type of cord
FIGURE 1B.
1-23. Which of the following is NOT an acceptable
1-17. When using the safety shorting probe to procedure to follow when using a portable
discharge a 30 µF capacitor, what is the electric drill?
maximum safe voltage to discharge?
1. Lay out the cord so no one will trip over it
1. 100 KV 2. Wear safety goggles
2. 1,000 KV 3. Use a three-conductor extension cord
3. 10,000 V 4. Remove the third prong when a
4. 1,000 V three-hole receptacle is not available

1-18. Before disconnecting a meter, what should you 1-24. What is the most delicate part of a piece of test
do to the current transformer? equipment?

1. Open the secondary 1. The meter

2. Short circuit the primary 2. The range adjustment
3. Short circuit the secondary 3. The faceplate
4. Ground the secondary 4. The power supply

1-19. Most potential transformer primary windings 1-25. The top surfaces of electric workbenches must
are protected by what types of devices? be insulated with what type of material?

1. Fuses 1. Rubber matting and adhesive

2. Switches 2. 3/8-inch Benelex 401
3. Resistors 3. 1/8-inch Benelex 401
4. Capacitors 4. 1/8-inch rubber insulation

3
1-26. A workbench must be secured to the deck. 1-32. After reporting on board ship, at what point
should naval personnel become acquainted
1. True with the types and locations of fire-fighting
2. False equipment?

1-27. All electrical workbench receptacles must be 1. After being assigned to a repair party
supplied from a common or an isolation 2. After qualifying in damage control
transformer. 3. As soon as possible
4. As needed
1. True
2. False 1-33. What is the safest type of fire-extinguishing
agent for you to use on an electrical fire?
1-28. If you need to find information about the
approved deck coverings to use in your work 1. Potassium bicarbonate (PKP)
area, you should refer to what publication? 2. Soda acid
3. Carbon dioxide (CO2)
1. OPNAVINST 3120.32 4. Foam
2. OPNAVINST 5100.19
3. NEETS 1-34. During a fire, what person determines whether
4. NSTM, chapter 634 the power should be secured?

1-29. The dielectric feature of electrical rubber 1. The repair party leader
gloves is based on what characteristic, if any, 2. The on-scene leader
of the glove? 3. The repair party electrician
4. Damage control central
1. The color of the label
2. The wall thickness of the glove 1-35. When it becomes necessary to rig casualty
3. The size of the glove power cables, what person(s) is/are responsible
4. None for tying the cables up in the overhead?

1-30. When operating a deck buffer rated at 120 1. The repair party electrician
volts, what is the lowest class of rubber gloves 2. The on-scene leader
that you can safely wear? 3. The person assigned by the locker leader
4. All members of the repair party
1. I
2. II
3. III Learning Objective: Recognize the effects of
4. 0 electric shock on the human body, and identify the
procedures for rescuing a person in contact with an
1-31. To ensure maximum protection from floor energized circuit. Identify the procedures for
matting, you should take all EXCEPT which of resuscitating an unconscious person.
the following actions?
1-36. If a person is unconscious because of an
1. Use general-purpose black floor matting
electric shock, you should start artificial
2. Clean the matting whenever it becomes
respiration at what point?
contaminated
3. Make sure the matting is always in place
1. As soon as possible
4. Use MILSPEC MIL-M-15562 matting
2. After assistance arrives
3. When ordered by senior personnel
Learning Objective: Recognize various aspects 4. After transporting the person to sick bay
of damage control.

4
1-37. A person has just received an electrical shock 1-41. When administering CPR to an adult, you
from an electric drill, and you cannot find the should depress the sternum what approximate
switch or receptacle. What is the quickest and distance?
safest method for you to use to free the victim?
1. 1 1/2 to 2 inches
1. Turn the drill switch off 2. 2 to 3 inches
2. Cut the portable cable 3. 3 inches
3. Pull the fuses at the distribution box 4. 1/2 to 1 inch
4. Pull the flexible cable of the drill until the
victim is clear of its contact
Learning Objective: Recognize the various types
1-38. A person has stopped breathing but is still of injuries and identify first aid procedures.
alive. This person is said to be in which of the
following states?
1-42. What type of wound has torn skin and tissue?
1. Cardiac arrest
1. An abrasion
2. Near-death experience
2. An incision
3. Respiratory failure
3. A laceration
4. Suspended animation
4. A contusion
1-39. To prepare a victim quickly for administration
1-43. What measure is the last resort when trying to
of mouth-to-mouth artificial respiration, you
control bleeding?
should take which of the following steps?
1. Applying direct pressure to the wound
1. Place the victim face down on a level
2. Using a tourniquet
area, slide a folded blanket under the
3. Using pressure points
stomach, and drain saliva from the mouth
4. Using back pressure
2. Place the victim face upon a level area,
slide a folded blanket under the small of
1-44. What method, if any, should you use to
the back, lift the lower jaw forward, and
indicate to medical personnel that a victim has
depress the tongue
had a tourniquet applied?
3. Place the victim face up, clear the mouth
and throat, tilt the head back, lift the
1. Mark his/her forehead with a capital letter
lower jaw, and pinch the nose shut
T
4. Place the person in comfortable
2. Have the patient tell them
surroundings, loosen the shirt collar and
3. Have the patient tell them to look on
other tight-fitting clothing, turn the head to
his/her medical record
one side, and drain the saliva from the mouth
4. None; they will see it when they examine
the patient
1-40. Which of the following actions should NOT be
performed during the administration of
closed-chest massage? A. THERMAL BURN
B. ELECTRICAL BURN
1. Apply pressure to the breastbone at the C. CHEMICAL BURN
rate of 60 to 80 times a minute
2. Apply the least pressure that will secure Figure 1C.
an effective pulse beat
3. Apply pressure to the chest wall with the
fingers at the rate of 2 to 15 times per minute
4. Pause from time to time to see if a
spontaneous heartbeat has returned

5
IN ANSWERING QUESTIONS 1-45 THROUGH 1-48, 1-51. When steam blisters cover half of a victim’s
REFER TO FIGURE 1C AND SELECT THE BURN back, (a) what percentage of (b) what class
DEFINED BY THE QUESTION. burn exists?

1-45. Caused by chemical action on tissue. 1. (a) 9 % (b) third degree

2. (a) 18 % (b) second degree
1. A 3. (a) 9 % (b) second degree
2. B 4. (a) 18 % (b) third degree
3. C
1-52. When treating a victim with second or third
1-46. A direct result of heat caused by the fire. degree burns, you should treat for what
symptom first?
1. A
2. B 1. Shock
3. C 2. Burn
3. Pain
1-47. Caused by electrical current passing through 4. Fluid loss
tissue.

1. A Learning Objective: Identify factors that cause

2. B environmental harm and recognize precautionary
3. C measures.

1-48. Caused by exposure of the tissue to steam.

1-53. Personnel that work in noise-hazardous areas
with a noise level of 84 dB and above are
1. A
required to have a hearing test within what
2. B
specified period of time after reporting aboard
3. C
ship?
1-49. Burns of what degree are characterized by
1. 12 months
blistering of the skin?
2. 6 months
3. 90 days
1. First
4. 30 days
2. Second
3. Third
1-54. At what minimum decibel level is double
4. Fourth
hearing protection required?
IN ANSWERING QUESTIONS 1-50 AND 1-51,
1. 104 dB
REFER TO FIGURE 1-15 IN YOUR TEXT.
2. 84 dB
3. 64 dB
1-50. What percentage of a person is considered
4. 54 dB
burned when the burned area is confined to the
right leg?
1-55. Heat stress is caused by the body trying to
regulate its temperature. Which of the
1. 1%
following is/are cause(s) of heat stress?
2. 9%
3. 18 %
1. Air temperature
4. 30 %
2. Thermal radiation
3. Humidity
4. All of the above

6
1-56. Which of the following is NOT a cause of heat 1-61. Electrical equipment should be painted only
stress? when the lack of paint will cause what
condition?
1. A ship operating in a hot or humid climate
2. Excessive steam and water leaks 1. Overheating
3. Missing or deteriorated pipe lagging 2. Corrosion
4. Ventilation operating properly 3. Electric shock
4. Shabby, unimpressive equipment
1-57. A heat stress survey is required in any space
when the ambient temperature reaches or 1-62. Which of the following actions should NOT be
exceeds what minimum temperature? taken to prevent corrosion?

1. 90°F 1. Apply primer to bare metal

2. 100°F 2. Paint identification plates
3. 120°F 3. Use approved solvents when treating
4. 140°F surfaces
4. Cover moving parts with silicon lubricant
1-58. The reason for conducting a heat survey of a
space is to 1-63. What are the two types of insulating varnish?

1. determine the air temperature 1. Clear-baking and shellac

2. look for steam leaks 2. Clear, air-drying and lacquer
3. identify problems 3. Shellac and lacquer
4. determine the safe stay time for personnel 4. Clear-baking and air-drying

1-64. When the use of water-based solvent is not

Learning Objective: Identify hazardous practical, what cleaner is recommended?
materials and recognize the precautions to take
when handling such materials. 1. Inhibited methyl chloroform
2. Carbon tetrachloride
3. Benzene
1-59. Of the following items, which one is NOT
4. Ether
considered a hazardous item?
1-65. What action should you take when using
1. Acid
cleaning solvents in a confined space?
2. Enamel paint
3. Coffee grounds
1. Provide a ventilation source to blow in
4. Oil
the space
2. Rig ventilation to blow out of the space
1-60. You can prevent an injury if you regard all
3. Open all portholes
aerosols as presenting what hazard?
4. Wear a dust mask
1. Flammable
1-66. You should NOT use which of the following
2. Foul smelling
types of material to clean electrical contacts?
3. Water based
4. Full of CFCs
1. Silver polish
2. Steel wool
3. Sandpaper
4. A burnishing tool

7
1-67. Of the factors listed below, which one(s) 1-72. Red tags are used when all EXCEPT which of
cause(s) cathode-ray tubes (CRTs) to be the following conditions exists?
classified as a hazardous material?
1. The operation of equipment could
1. They are subject to considerable force jeopardize the safety of watch standers
from atmospheric pressure 2. The operation of equipment would
2. The chemical coating inside is extremely damage a component
toxic 3. PMS is being performed on a system
3. Both 1 and 2 above 4. Special instructions are needed before the
4. They get extremely hot equipment can be operated

1-68. Of the following materials, which one is NOT 1-73. When two or more repair groups are
a hazardous material released when the glass performing repairs on a system, the
envelope of a CRT is broken? responsibility for posting a red tag rests with

1. Barium getters 1. each repair group

2. Barium acetate 2. the engineer officer
3. Thorium oxide 3. one repair group
4. Copper oxide 4. the officer of the deck

1-69. If you cannot return a CRT to the manufacturer

for disposal, what action should you take? Learning Objective: Identify shipboard organization
responsibilities.
1. Make it harmless by breaking the vacuum
glass seal
1-74. What function is derived from the manner in
2. Double bag it, and throw it away
which the engineering department is
3. Send the CRT to the nearest facility with
organized?
a burn room for disposal
4. Poke a hole through the face
1. It is used to develop a watchbill for
enlisted personnel aboard ship
Learning Objective: Identify the use of caution and 2. It provides for proper assignment of
danger tags. duties and for proper supervision of
personnel
3. It identifies personnel qualified for
1-70. Which of the following phrases is NOT advancement
allowed when a caution tag is used? 4. It prevents unqualified personnel from
operating equipment
1. CHECK OIL LEVEL PRIOR TO
OPERATION 1-75. Which of the following is/are the purpose(s) of
2. DO NOT OPERATE WITHOUT EOOW the National Apprenticeship Standards of the
PERMISSION U. S. Navy?
3. DO NOT OPERATE IN HIGH SPEED
4. DO NOT OVERCHARGE 1. To provide registered certification of the
rate training of Navy personnel
1-71. What publication contains an explanation of 2. To achieve recognition of the Navy
the steps required to tag out a piece of person equal to his/her civilian
equipment? counterpart
3. Both 1 and 2 above
1. SECNAVINST 5216.5 4. To ensure personnel are properly trained
2. OPNAVINST 3120.32 for their watchstation aboard ship
3. OPNAVINST 4790.4
4. NSTM, chapter 090

8
 ASSIGNMENT 2
Textbook Assignment: “Electrical Installations,” chapter 2, pages 2-1 through 2-55.

2-5. Flexing service cable designed for use aboard

Learning Objective: Identify various types, ship is commonly referred to as being portable
sizes, and uses of shipboard electrical cables because
according to their designations, markings,
and so forth. 1. it is principally used as leads to portable
electric equipment
2. it is principally used as leads to installed
2-1. What was the driving force for developing the
electric equipment
low smoke family of cables?
3. it is lighter than other types of cable
4. it is easily stripped of insulation
1. Smoke from fires causes standard cables
to become grounded
2-6. Repeated flexing, general use-cable is
2. The contract for the old style of cables
categorized by what means?
expired
3. The Navy needed a new cable that would
1. The ambient temperature rating
give off less toxic fumes and smoke
2. The voltage rating
during a fire
3. The current rating
4. Standard cables could not handle high
4. The number of conductors in the cable
current without smoking
2-7. If you see the symbol HOF on a cable designation,
2-2. Which of the following are classifications of
you know the cable is of what type?
cable types?
1. Repeated flexing service, experimental
1. Special purpose
2. Heat and oil resistant, flexible
2. Nonflexing service
3. Heat resistant, synthetic rubber, extra
3. Repeated flexing service
flexible
4. Each of the above
4. Heat and oil resistant, nonflexible
2-3. What is the purpose of aluminum or steel
2-8. A cable listed in the Cable Comparison Guide
covering of armored cable?
has a 7 at the end of the cable designation.
Which of the following is the meaning of the 7?
1. To prevent interference from outside
electromagnetic sources
1. The number of conductor pairs and the
2. To give physical protection to the cable
circular mils of the conductor only
sheath during installation
2. The number of conductors, the number of
3. To prevent accidental damage from items
conductor pairs, and the circular mils
carried or moved nearby
3. Either 1 or 2 above, depending on the
4. To provide a magnetic field for
type of cable
degaussing the ship
4. It has a resistance of 7Ω per foot
2-4. Which of the following is a purpose for using
2-9. A radio frequency (RF) cable designated as
nonflexing cables?
LSTTRSU-10 in the Cable Comparison Guide
has what total number of conductors?
1. To use with portable tools
2. To use with permanent installations
1. 20
3. To use as casualty power only
2. 40
4. To prevent battle damage
3. 60
4. 80

9
2-10. The designation of a nonflexing service cable 2-14. When selecting a replacement cable for a
is LSDHOF-400. What does (a) the letter D particular installation, you must know all
and (b) the number 400 indicate? EXCEPT which of the following factors?

1. (a) Degaussing 1. The demand factor

(b) approximate cross-sectional area of a 2. The allowable voltage drop
single conductor expressed in 3. The total connected load current
thousands of circular mills 4. The number of bends in the cable
2. (a) Two conductors
(b) number of strands per conductor 2-15. Before choosing the size of cable to use in a
3. (a) Two conductors circuit installation, what information is
(b) approximate cross-sectional area of a necessary for you to know?
single conductor expressed in
thousands of circular mills 1. The demand factor, the total connected
4. (a) Degaussing load current, and the voltage of the circuit
(b) number of strands per conductor 2. The total connected load current, the
power factor, and the allowable voltage
2-11. If you need to find a comprehensive listing of the drop
requirements for installing cables aboard Navy 3. The ambient temperature, the total
ships, you should refer to what publication? connected load current, and the demand
factor
1. General Specifications for Ships of the U.S. 4. The total connected load current, the
Navy, NAVSEA S9AAO-AA-SPN-010 demand factor, and the allowable voltage
2. Electrician’s Mate, OPNAVINST 4790.4 drop
3. 3-M Manual, OPNAVINST 4790.4
4. Ship’s Organization and Regulations 2-16. Which, if any, of the following is the reason
Manual, OPNAVINST 3120.32 for keeping cable runs as short as possible?

2-12. A cable has been constructed so that it 1. To lower construction costs

provides added protection, allowing it to 2. To keep attenuation to a minimum
function for a longer period under fire 3. To simplify damage control efforts
conditions. What term describes this cable? 4. None of the above

1. Armored cable 2-17. When determining the total connected load

2. Circuit integrity current for a dc power circuit, you should add
3. Watertight integrity what number of watts for each installed
4. Special use cable receptacle?

2-13. What information is on the thin marker tape 1. 50

present on most cables and cords under the 2. 100
binder or jacket? 3. 150
4. 200
1. Name and location of the manufacturer
2. The year the cord or cable was made 2-18. What letters would be used to designate an
3. The MILSPEC number of the cord or cable emergency lighting circuit on a cable
4. All of the above supplying 115 volts ac to a circuit with a load
of 120 watts?

1. EL
2. EP
3. L
4. C

10
 2-23. Neutral polarity in a conductor is identified by
Learning Objective: Identify installation, what color?
repair, and protection procedures.
1. Red
2. Black
2-19. You are installing new cables. You should
3. White
measure the bend radius at what point on the
4. Blue
cable?
2-24. The marking system for power and lighting
1. On the top of the cable
cables is shown in what sequence?
2. On the bottom of the cable
3. On the innermost portion of the cable
1. Source, voltage, and service
4. On the outside of the cable away from the
2. Voltage, source, and service
bend
3. Service, source, and voltage
4. Source, service, and voltage
2-20. In what publication will you find the exact
method to use when installing cables?
2-25. A cable marked as (1-120-2)-24-C(2) indicates
that the circuit is supplying what maximum
1. Electronics Installation and Maintenance
voltage?
Handbook (EIMB)
2. NSTM
1. 12 V
3. Cable Comparison Guide
2. 24 V
4. NAVEDTRA 12164
3. 120 V
4. 220 V
2-21. What action should you take before you clamp
a solder-type terminal to a conductor?
2-26. A circuit marking of (4-168-1)-4P-A(1)
indicates that the circuit is supplying (a) what
1. Untwist and tin the strands
voltages of (b) what type power?
2. Twist the strands tightly only
3. Twist the strands tightly and solder them
1. (a) 450 V (b) casualty
only
2. (a) 115 V (b) casualty
4. Twist the strands tightly, solder them, and
3. (a) 450 V (b) ship’s service
tin the terminal board
4. (a) 115 V (b) ship’s service
2-22. A cable has been newly installed. What type
2-27. If you want cable to present a neat appearance
of meter should you use to test the insulation
and to be traced easily in equipment, you
resistance?
should take what action?
1. A megger
1. Wrap them together with tape
2. An ammeter
2. Secure them to the side of the equipment
3. A wattmeter
with small lengths of wire
4. A voltmeter
3. Twist the wires together
4. Lace them together

11
 Figure 2A.

IN ANSWERING QUESTIONS 2-28 AND 2-29, 2-29. With the circuit in the condition shown, a ground
REFER TO THE TYPICAL POWER FEEDER is detected in the power circuit at point 3. What
SHOWN IN FIGURE 2A. should be done to isolate the faulty section and
locate the ground?

Learning Objective: Recognize the steps to 1. Open all breakers shown and use a
take when troubleshooting a distribution Megger to test each circuit individually to
system. localize the fault
2. Use a Megger to test the motor leads to
find what phase is at fault
2-28. To isolate the legs or phase leads of the power
3. Operate the switchboard ground detector
circuit, you should take which of the following
to find what phase is grounded
steps?
4. Stop each piece of equipment fed from
the power distribution panel until the
1. Open the switches or circuit breakers at
ground disappears
the power distribution panel
2. Make sure the motor controller
contractors are open Learning Objective: Recognize the purpose for
3. Both 1 and 2 above cable maintenance and insulation, and identify
4. Remove the ground straps and clips the properties of different insulating materials.

2-30. What is the primary purpose of cable

maintenance?

1. To keep the wireways clean and free of

dust
2. To preserve the insulation resistance
3. To prevent damage to the cables
4. To prevent loose connections

12
2-31. Which of the following purposes is/are served by 2-36. Asbestos.
insulation on electric cables and equipment?
1. A
1. Isolating current-carrying conductors and 2. B
conductive structural parts of other 3. C
circuits or equipment 4. D
2. Insulating points of unequal potential
from one another 2-37. Shipboard lighting transformers in a 60-hertz
3. Both 1 and 2 above circuit are constructed using what class
4. Protecting the current-carrying insulation?
conductors from interference from
outside electromagnetic sources 1. Class A
2. Class B
2-32. Electrical insulating materials are classified 3. Class C
according to what characteristic? 4. Class O

1. Their material composition 2-38. What is the limiting temperature of a piece of

2. Their temperature index equipment with class N insulation?
3. Their resistivity coefficient
4. Their thickness 1. 155°C
2. 180°F
3. 200°F
A. CLASS A
4. 200°C
B. CLASS B
C. CLASS C
D. CLASS O Learning Objective: Identify the procedures
for measuring circuit insulation resistance.

Figure 2B.
2-39. If local lighting switches are double pole, leaving
IN ANSWERING QUESTIONS 2-33 THROUGH 2-36, them open allows their insulation resistance to be
SELECT THE CLASS OF INSULATION FROM measured when testing the local branch circuit.
FIGURE 2B THAT IS ASSOCIATED WITH THE
MATERIAL USED AS THE QUESTION. 1. True
2. False
2-33. Impregnated cotton.
2-40. When measuring the insulation resistance of an
1. A armored power cable with a Megger, what is
2. B the maximum desired resistance from the cable
3. C armor to ground?
4. D
1. 0Ω
2-34. Quartz. 2. 100W
3. 1MΩ
1. A 4. Greater than 1 M Ω
2. B
3. C 2-41. When measuring the insulation resistance of a
4. D complete lighting circuit with a Megger, what
is the minimum desired resistance to ground?
2-35. Paper.
1. Less than 1 Ω
1. A 2. 1Ω
2. B 3. 500,000 Ω
3. C 4. More than 1 MΩ
4. D
13
2-42. You would use a nomograph when taking what 2-47. The shore-power system is designed to provide
measurement? enough power for all equipment normally
energized while at sea.
1. The resistance/foot of a cable
2. To correct a resistance reading of a cable 1. True
3. To translate a resistance reading to a 2. False
temperature index
4. To correct a resistance reading of a piece 2-48. You are connecting casualty power cables in a
of equipment dark compartment. What conductor feature is
identified by three separate servings of twine
2-43. If a cable has been energized for 6 hours, what or O-rings?
temperature should the cable be assumed to be
for purposes of heating resistance? 1. Phase A
2. Phase C
1. 40°F 3. The conductor polarity
2. 70°F 4. The neutral connection
3. 90°F
4. 104°F 2-49. What type of cable is used to connect fixed
terminals that penetrate decks and bulkheads?

Learning Objective: Identify the procedures 1. LSTSGU-75

you should use to prepare, use, and care for 2. LSDSGU-75
casualty power and shore power cables. 3. LSTHOF-75
4. LSDHOF-75
2-44. What is the size and designation for casualty
power cables on ac power systems?
Learning Objective: Identify equipment needs,
installation methods, and testing procedures
1. LSDHOF-93
that are required when connecting shore power.
2. LSMHOF-3
3. LSTHOF-42
4. LSFHOF-48
2-50. Shore power is supplied to the ship through the
2-45. Casualty power cable leads are color coded for use of (a) what specific length of (b) what type
identification. What are the proper colors for of cable?
A, B, and C phases, respectively?
1. (a) 175 feet (b) THOF-400
1. Red, white, and black 2. (a) 175 feet (b) TSGU-400
2. Black, white, and red 3. (a) 150 feet (b) THOF-400
3. Black, red, and white 4. (a) 150 feet (b) TSGU-400
4. Red, black, and white
2-51. You are testing the phase sequence of a shore
2-46. To provide or install shore power to a ship connection. What is indicated by a clockwise
requires which of the following equipment? rotation of the phase sequence indicator?

1. Shore power station and receptacle 1. Correct phase sequence

2. Connecting cable 2. Incorrect phase at the shore station
3. Cable plug 3. High voltage at the shore station
4. All of the above 4. Three-phase power is not available

14
2-52. Kickpipes that penetrate wooden decks should 2-56. What type of protection is provided by reverse-
be made from what material? power relays?

1. Iron 1. They protect the generators from damage

2. Aluminum by motoring prime movers
3. Steel 2. They prevent the motoring generator
4. Neoprene from damaging the prime movers
3. They prevent loss of power to the prime
movers
Learning Objective: Recognize the operating 4. They limit the amount of circulating
fundamentals of electrical switches and protection current between paralleled generators
devices.

2-53. Limit switches are installed so they are

connected in what configuration with (a) the
master switch and (b) the voltage supply
circuit?

1. (a) Parallel (b) parallel

2. (a) Parallel (b) series
3. (a) Series (b) parallel
4. (a) Series (b) series

2-54. What is a pilot device?

1. A large device that controls other large

Figure 2C.
devices
2. A small device that controls a large
IN ANSWERING QUESTIONS 2-57 AND 2-58,
device
REFER TO FIGURE 2C.
3. A large device that controls a small
device
2-57. Oscillations in the induction disk of the timer
4. A small device that controls other small
element of the relay are dampened by which
devices
component?
2-55. A thermal overload relay is adjusted to trip at a
1. A
predetermined value. What action can you
2. B
take to vary the tripping current?
3. C
4. D
1. Change the relative position of the
contacts
2-58. What condition must take place to cause
2. Raise and lower the dashpot plunger
reverse rotation of the disk?
3. Rotate the splitter arm
4. Move the relay heater coil
1. The polarity of power through coil A
must be in a direction that will cause a
Learning Objective: Recognize the operating torque on the disk through a reaction with
principles and identify the repair procedures for the fluxes of the upper and lower poles
circuit breakers. 2. The polarity of coil E must reverse with
respect to the polarity of coil F
3. The current through coils A and B must
reverse with respect to the polarity of
coils E and F
4. The current through coils E and F must
reverse with respect to the polarity of coil B
15
2-59. When two or more dc generators are connected 2-64. Which of the following trip elements should
in parallel, what device disconnects a generator NOT be used on the AQB-A250 circuit
from the line if the generator starts drawing breaker?
power from the line?
1. 300 A
1. A thermal-type relay 2. 275 A
2. A reverse-power relay 3. 150 A
3. A magnetic-type relay 4. 125 A
4. A reverse-current relay
2-65. The instantaneous trip setting of the AQB-A250
2-60. The polarity of the voltage applied to the circuit breaker is adjusted by using what
potential coil on a reverse-current relay will components?
remain the same when the generator terminal
current is reversed. 1. Thermal studs
2. Shunt trips
1. True 3. Trip coils
2. False 4. Adjusting wheels

2-61. To actuate a phase-failure relay, what action 2-66. Which of the following circuit breakers must
must take place? be manually operated to interrupt current
flow?
1. A flux cancellation between the flux
produced in the relay coils and the flux 1. Type NQB
produced in the coils in the Rectox unit 2. Type NLB
2. An imbalance of current through the relay 3. Both 1 and 2 above
coils 4. Type ACB
3. A flux cancellation between the flux
produced by one relay and one coil in the 2-67. Which of the following conditions is most
Rectox unit, and the flux produced by the likely to cause a relay magnet to chatter?
other relay coil and the other coil in the
Rectox unit 1. Rusty magnet sealing surfaces
4. An imbalance between the flux produced 2. Shorted coils
in the relays in the Rectox unit 3. Open coils
4. Burned contacts
2-62. What is used to compensate for variations in
reactance of the reactors introduced during 2-68. Selective tripping is useful aboard ship for
manufacturing? what reason?

1. Two resistors 1. It allows overcurrents to flow in the

2. An inductor is placed in each Rectox circuits
3. A bridge rectifier is placed in series with 2. It systematically opens all circuits when
the reactors damage occurs
4. Two 2-coil reactors 3. It maintains overcurrents where fuses will
not
2-63. What is the closing sequence of the contacts in 4. It isolates faulty circuits without
an ACB circuit breaker? interrupting other associated circuits

1. Main contacts close only

2. Arcing contacts and the main contacts Learning Objective: Recognize the proper
close together procedures for installing power cords and
3. Arcing contacts close; then the main testing portable equipment.
contacts close
4. The main contacts close; then the arcing
contacts close
16
2-69. When testing a grounded receptacle, what is 2-73. A magnetic-type overload dashpot relay tends
the maximum acceptable resistance from the to trip before the overload current becomes
ground connection to the ship’s hull? excessive. How can you adjust the relay to trip
at a greater current?
1. Less than 1 Ω
2. 0.0001 Ω 1. Lower the plunger by turning the dashpot
3. 1.0 Ω in a reverse direction
4. 1.05 Ω 2. Raise the plunger by turning the dashpot
in a forward direction
2-70. At what interval should the connections of new 3. Lower the indicating plate
portable electric wiring be tested? 4. Raise the indicating plate

1. Before being used for the first time

2. Before every use
3. Semiannually
4. Annually

2-71. While testing the power cord of a portable electric

drill, you notice a fluctuation in the resistance
reading. The fluctuating resistance reading
indicates which of the following problems?

1. A short
2. A ground
3. A faulty cable
4. Each of the above

Figure 2D.

IN ANSWERING QUESTION 2-72, REFER TO

FIGURE 2D.

2-72. Switch S2 is closed and switch S1 is in the

automatic position. Under normal load
conditions, which component controls starting
and stopping of the motor?

1. The fuse
2. The main contact for L2
3. The pilot device
4. The main contact for L1
17
 ASSIGNMENT 3
Textbook Assignment: “AC Power Distribution Systems,” chapter 3, pages 3-1 through 3-40.

3-4. What information is contained on circuit

Learning Objective: Identify the purpose information plates located on distribution
and functions of the components of ac power panels?
distribution systems.
1. The circuit number and the name of the
circuit controlled only
3-1. Which, if any, of the following systems
2. The circuit number, the name of the
make(s) up the power distribution system?
circuit controlled, and the space served
3. The space served and the circuit number
1. The casualty power system
only
2. The emergency power system
4. The space served, the circuit number, and
3. The ship’s service system
the circuit power used
4. All of the above
3-5. You are troubleshooting a circuit and you want
3-2. What is the function of the switchboard bus
to know the maximum allowed current. This
ties?
information is marked on which, if any, of the
following plates?
1. To permit switchboards to be cross
connected and to allow paralleling of
1. Distribution panel circuit information
generators
plate
2. To allow power distribution direct from
2. Distribution panel cabinet information
the generator to the load
plate
3. To allow the generators to operate in
3. Cable identification plate
series
4. None of the above
4. To feed power to the dc generator
3-6. For what reason, if any, is the phase sequence
3-3. On small ships, locating distribution panels
important to the distribution system aboard ship?
centrally with respect to the load and feeding
them directly from the generators has which of
1. An improper phase sequence will cause
the following advantages?
voltage fluctuations
2. The phase sequence determines the
1. It simplifies the installation
amount of current available
2. It reduces the weight and space
3. The phase sequence determines the
requirements
direction of rotation of three-phase
3. It reduces equipment requirements
motors
4. Each of the above
4. None; the phase sequence has no effect
on the distribution system
Learning Objective: Identify information
found on circuit identification plates and 3-7. What is the advantage of using an MBT as an
recognize the importance of identifying the alternate power source to a vital load?
phase sequence in power distribution systems.
1. Circuit conditions can be met before
energizing
2. Automatic switching of power supplies
3. The load can be secured faster in an
emergency
4. The maintaining of 58% of the lighting
circuits if one phase is lost

18
 Learning Objective: Identify the characteristics
and uses of critical hardware components of ac
power distribution systems.

3-8. What service is provided by bus transfer

equipment?

1. Short-circuit protection to the ship’s

Figure 3A.
service generators
2. Prevention of overloading the generator
IN ANSWERING QUESTIONS 3-12 AND 3-13,
circuit breakers
REFER TO FIGURE 3A.
3. Prevent paralleling of two switchboards if
the voltage and current relationships are
3-12. If lamp A is out when switch S is open, what
improper
problem is indicated?
4. Two sources of power to equipment that
is vital to the ship
1. Phase A is grounded
2. Lamp A is burned out
3-9. Aboard ships, switchgear groups are physically
3. Phases B and C are shorted
separated as much as practical for what
4. Phase A is partially grounded
reason?
3-13. What indication is given if lamp C is dim when
1. To allow easy access for maintenance
switch S is closed?
2. To prevent accidental loss of power
3. To afford greater protection from damage
1. Phase C has a ground
during battle
2. Phase B is shorted
4. To prevent unnecessary weight during
3. Phase A is open
construction
4. Phase C has a partial open
3-10. Which of the following is NOT a function
provided by switchboards aboard ships? Learning Objective: Recognize the operating principles
of ac generators, including related construction features
1. Automatic shifting of power to alternate and devices needed to drive them.
sources if normal power is lost
2. Distribution of three-phase, 450-volt
power 3-14. The output of all ac generators is generated in
3. Circuit protection what winding?
4. Control, monitoring, and protection of the
ship’s service generators 1. The field winding
2. The stator winding
3-11. What is the purpose of the disconnect links? 3. The rotor winding
4. The armature winding
1. They provide a convenient means of load
testing ship’s service generators 3-15. Revolving armature generators are seldom
2. They provide a means of securing power used for what reason?
to a switchboard during a fire
3. They enable repairs to be conducted to 1. Their output power is conducted through
one switchboard without affecting the fixed terminals
operation of the whole system 2. They are subject to arc-over at high
4. They are used to provide overcurrent voltages
protection to the main bus 3. They are physically larger than other
types of generators
4. They are more expensive to operate

19
3-16. When dealing with the load rating of ac 3-21. The rotary force from the prime mover is
generators, what factor must be accounted for? transmitted to the ac generator by which of the
following components?
1. The internal heat the generator can
withstand 1. Stator
2. The speed of the generator 2. Exciter field
3. The weight of the field windings 3. Rotor drive shaft
4. The type of voltage regulator used 4. AC generator armature

3-17. Which of the following statements defines the

term power factor? Learning Objective: Identify the operating
principles of single-, two-, and three-phase ac
1. The difference between the voltage and generators, including the wye- and delta-connected
the current types.
2. It is set at 0.08 lagging
3. The product of the voltage and the current
of the system
4. The expression of the losses within the
electrical distribution system

3-18. AC generator sets may be divided into what

two classes?

1. Low-speed, turbine-driven and high-speed,

engine-driven
2. High-speed, turbine-driven and high-speed, Figure 3B.
engine-driven
IN ANSWERING QUESTION 3-22, REFER TO
3. Low-speed, engine-driven and high-speed,
FIGURE 3B.
turbine-driven
4. Low-speed, engine-driven and low-speed,
3-22. What is the magnitude of the voltage across
turbine-driven
any two phases?
3-19. What function is provided by ac generator
1. Larger than the voltage across a single
exciters?
phase
2. Equal to the sum of the voltage across all
1. DC to the field windings
three phases
2. DC to the load
3. Equal to the voltage across a single phase
3. AC to the stationary armature
4. Smaller than the voltage across a single
4. AC to the stationary field windings
phase
3-20. The rotary force used to provide the rotating
3-23. When you use vectors to analyze ac circuits,
action in generators may be supplied by which
what rotation direction represents (a) positive
of the following prime movers?
and (b) negative polarity?
1. An electric motor
1. (a) Right (b) left
2. A turbine
2. (a) Counterclockwise (b) clockwise
3. An internal combustion engine
3. (a) Right (b) clockwise
4. Each of the above
4. (a) Counterclockwise (b) left

20
3-24. In a purely capacitive circuit, what is the 3-29. The line voltage of a wye-connected stator
relationship between voltage and current? with a balanced load isn’t twice the phase
voltage for what reason?
1. Voltage leads current
2. Voltage and current are in phase 1. The loads seen by the generator are
3. Current leads voltage usually inductive
4. Current lags voltage 2. The load across each line is different
3. The line currents are unequal
3-25. A generator is operating at 450 volts ac, 60 4. The phase voltages are out of phase with
hertz, supplying a load of 1,000 amperes and each other
306,000 watts. What is the power factor?
3-30. At which of the following points will a
1. 1.24 generator’s output voltage increase?
2. 0.80
3. 0.75 1. When the rotating field strength increases
4. 0.68 2. When the load increases
3. Both 1 and 2 above
3-26. When the phase voltage is 100 volts in a delta- 4. When the rotor speed decreases
connected ac generator, what is the line or load
voltage? 3-31. A decrease in general terminal voltage caused
by an inductive load is partly the result of
1. 200.0 V which of the following actions?
2. 173.0 V
3. 100.0 V 1. Reduced current through the armature
4. 70.7 V conductors
2. Increased dc field flux caused by the
3-27. When the phase current in a balanced delta- aiding action of the armature mmf
connected generator is 20 amperes, what is the 3. Reduced dc field flux caused by the
line current? opposing action of the armature mmf
4. Increased armature mmf produced by
1. 34.6 A increased field flux
2. 20.0 A
3. 10.0 A 3-32. The most practical method to control voltage
4. 6.6 A of an ac generator is to regulate the generator’s
speed.

Learning Objective: Identify the factors that 1. True

determine the output frequency and voltage of 2. False
ac generators, and recognize the principles 01
generator synchronization and voltage
regulation. Learning Objective: Identify the operational
principles, characteristics, and design features
of transformers.
3-28. The output frequency of an ac generator varies
directly with which of the following generator
characteristics? 3-33. In transformers, electrical energy is transferred
from one circuit to another through which of
1. The number of poles on the rotor the following actions?
2. The speed of rotation of the rotor
3. Both 1 and 2 above 1. Hysteresis coupling
4. The frequency of the field current 2. Electrostatic radiation
3. Electromagnetic induction
4. Resistive-capacitive coupling

21
3-34. When a transformer transfers electrical energy, 3-40. A transformer’s efficiency is stated as a ratio
what elements are either increased or of what factor of the transformer’s input to
decreased by the transformer? output?

1. Current and voltage only 1. Power

2. Frequency and current only 2. Line loss
3. Voltage and frequency only 3. Phase current
4. Frequency, voltage, and current 4. Voltage

3-35. In a transformer, what winding is designated as 3-41. Which of the following losses does NOT affect
the primary? the efficiency of a transformer?

1. The one with the highest voltage 1. Hysteresis losses

2. The one with the lowest voltage 2. Eddy current losses
3. The one that delivers energy to the load 3. Leakage reactance losses
4. The one that receives energy from an ac 4. Copper losses
source

3-36. You can reduce eddy current losses in the core Learning Objective: Identify the operational
of a transformer by installing which of the features of various transformer connections.
following components?
3-42. To obtain maximum current output from a
1. Grain-oriented material
single-phase transformer, you should connect
2. Heat-treated core material
the sections of the secondary windings in what
3. Thin, insulated lamination
configuration?
4. Subdivided windings
1. Series-opposing
3-37. In a transformer, the low-voltage winding is
2. Parallel-opposing
placed next to the core instead of the high-
3. Series-adding
voltage winding for what reason?
4. Parallel-adding
1. To reduce Ir drop
3-43. When a large number of single-phase loads are
2. To reduce leakage flux
supplied from a three-phase transformer bank,
3. To reduce hysteresis loss
what is the desirable connection of the
4. To reduce insulation requirements
transformer secondary?
3-38. In each winding of a transformer, the total
1. Wye
induced voltage has what relationship to the
2. Delta
number of turns in that winding?
3. High voltage
4. Low power factor
1. Proportional
2. Reciprocal
3-44. What letter is used to identify the secondary
3. Additive
winding of a power transformer?
4. Subtractive
1. H
3-39. Because of damage caused by heat, you should
2. L
NOT operate a transformer rated at 400 hertz
3. T
at which of the following frequencies?
4. X
1. 450
2. 420
3. 370
4. 340

22
3-45. Which of the following types of equipment are 3-50. Casualty power bulkhead terminals are
used to supply 400 hertz power to a transformer? permanently installed on opposite sides of the
bulkhead for what reason?
1. Motor generator units
2. Static converters 1. To provide casualty power to selected
3. Both 1 and 2 above equipment
4. Steam turbines 2. To transmit power through compartments
without loss of watertight integrity
3-46. What are the two principal types of transformer 3. To transmit power through decks without
construction? loss of watertight integrity
4. To provide a means of making proper
1. Shell and pancake phase polarity checks
2. Polyphase and single phase
3. Core and shell 3-51. When a generator is used exclusively for
4. Power and current casualty power purposes, you must perform
which of the following actions?
3-47. By what means are hysteresis losses kept to a
minimum in transformers? 1. Open the generator circuit breaker
2. Open the generator disconnect links
1. By using grain-oriented, silicon steel 3. Strip the switchboard that the generator is
laminations in the core feeding
2. By insulating adjacent lamination sections 4. Transfer all bus transfer switches to
3. By regulating the temperature of the emergency power
transformer
4. By using pancake coils instead of round 3-52. A portable cable used to rig ac casualty power
wire in the secondary systems can carry (a) what maximum current
for (b) what maximum number of hours?
3-48. If a transformer is wound with 100 turns on the
primary, 150 turns on the secondary, and has a 1. (a) 92 A (b) 4
secondary voltage of 600 volts, what voltage is 2. (a) 92 A (b) 40
applied to the primary? 3. (a) 200 A (b) 40
4. (a) 200 A (b) 4
1. 600 V
2. 400 V 3-53. When unrigging casualty power, what
3. 250 V procedure should you follow?
4. 200 V
1. Remove both ends of the first cable at the
power source, remove both ends of the
Learning Objective: Recognize the various last cable at the load, and then unrig the
principles and procedures used to rig or unrig remaining cables
casualty power. 2. Remove both ends of the last cable at the
load, and then proceed step-by-step to the
power source
3-49. What is the main purpose of the casualty
3. Unrig the cable between the power source
power system?
and the load, and then proceed to the
power source and load
1. To make temporary connections to vital
4. Remove both ends of the first cable at the
circuits
power source, and then proceed step-by-
2. To make permanent connections to vital
step to the load
equipment
3. To make permanent connections to vital
circuits
4. To make temporary connections to
furnish power to ac generators

23
3-54. Shore power connections aboard ship may be 3-60. An exercise in rigging casualty power is not
used to supply power to another ship considered completed until damage control
alongside. central receives the report stating that what
action(s) have been completed?
1. True
2. False 1. The equipment is operating on normal
power only
3-55. It is hazardous for a shore power installation to 2. All portable cables have been restored only
have one circuit breaker supplying more than 3. The equipment is operating on normal
one power cable for what reason? power and all portable cables have been
restored
1. A fire hazard is created when more than 4. Cables have been restored and PMS has
one cable is energized been accomplished
2. Phase rotation and orientation can’t be
verified without energizing all the cables 3-61. To what publication should you refer for the
at once insulation resistance requirements for shore
3. The cable may short circuit power cables?
4. A requirement for handling live cables
will exist when unrigging shore power 1. OPNAVINST 4790.4
2. OPNAVINST 5100.19
3-56. When testing shore power cables, what should 3. NSTM, chapter 300
be used as the shore ground resistance? 4. EIMB

1. The ship’s hull 3-62. When using spliced cables, what action should
2. A 16 AWG or larger wire with one side you take?
dropped over the side of the ship
3. The enclosure that houses the shore 1. Measure the cables to make sure they
power terminals or receptacles aren’t too short
4. Phase A of the shore power cable 2. Use spliced cables only in low-voltage
systems
3-57. The casualty power system provides a good 3. Remove all spliced connections from
means of testing repaired equipment without shore power cables
jeopardizing the normal electrical distribution 4. Make sure the phases are continuous and
system. have not been altered at the splice

1. True 3-63. What is the key component of the phase-

2. False sequence indicator?

3-58. What person is authorized to order the 1. The three-phase induction motor
energization of the casualty power system? 2. The saturable reactor
3. The three-phase Rectox unit in parallel
1. The damage control assistant with a fill-wave rectifier
2. The electrical officer 4. The digital display
3. The E division officer
4. The E division LCPO 3-64. When, if ever, is it permissible to move
energized shore power cables?
3-59. What is the (a) normal current carrying
capacity of portable casualty power cables and 1. When the ship is being inspected by an
(b) the casualty current-carrying capacity? admiral and the cable must be arranged
neatly
1. (a) 200 A (b) 93 A 2. While fighting a fire on the pier
2. (a) 93 A (b) 93 A 3. While troubleshooting the source of
3. (a) 200 A (b) 200 A smoke coming from the cables
4. (a) 93 A (b) 200 A 4. Never
24
3-65. In the formula Eg = Kθ N, what does the K 3-68. In a generator, what causes the armature
represent? reaction to be much larger than the armature
resistance?
1. The strength of the magnetic field
2. The synchronous speed of the magnetic 1. The large resistance of the coils compared
field to the small inductance
3. The generated voltage 2. The large inductance of the coils
4. The constant determined by the compared to the small resistance
construction 3. The higher temperature of the rotor
windings compared with the stator
3-66. By what means is the terminal voltage of an ac windings
generator varied? 4. The induction load on the governor

1. By varying the dc excitation to the field 3-69. Which of the following conditions causes the
winding efficiency of a power transformer to be less
2. By altering the power factor of the than 100%?
machine
3. By adding or removing the number of 1. The size of the resistive load on the
active coils in the field secondary
4. By varying the resistance of the field 2. The copper losses in the windings and the
winding hysteresis and eddy current losses in the
core
3-67. What is the cause of the terminal voltage of an 3. The IR drop in the windings and voltage
ac generator dropping? crossover from the primary to the
secondary windings
1. An IR drop only 4. Loose connections at the primary
2. An increased load only
3. An IR drop and increased load
4. Increased dc excitation to the field

25
 ASSIGNMENT 4
Textbook Assignment: “Shipboard Lighting,” chapter 4, pages 4-1 through 4-41.

Figure 4A.

IN ANSWERING QUESTIONS 4-1 AND 4-2, REFER 4-3. A vital lighting load receives its power from
TO FIGURE 4A. what total number of sources?

1. One
Learning Objective: Identify the fundamentals 2. Two
of a shipboard lighting distribution system. 3. Three
4. Four
4-1. What are the two sources of power to ABT-2?
4-4. It is preferable to connect lighting transformer
banks in a delta-delta configuration for what
1. Emergency switchboards 2E and 1E
reason?
2. Ship’s service switchboard 2E and 1E
3. Ship’s service switchboard 2SA and ship
1. If one of the transformers is damaged or fails,
service switchboard 2SB
the remaining two transformers will carry
4. Emergency switchboard 2E and ship’s
about 58% of the initial load capacity
service switchboard 2SA
2. It’s more economical to operate them in
this configuration than in a series
4-2. What, if anything, prevents both the alternate and
configuration
the normal power source breakers of the emergency
3. If connections overheat, there is less
switchboard from being closed at the same time?
chance of fire occurring
4. It allows less wiring to be used, saving weight
1. Vigilant watch standing
2. The circuit breakers are electrically and
mechanically interlocked Learning Objective: Identify various shipboard
3. The frequency and voltage monitoring lighting sources and lamps and recognize their use.
system
4. Nothing
26
4-5. In incandescent lamps above 50 watts, the inert 4-11. When you operate a lamp at a higher than rated
gas allows the lamp to operate in which of the voltage, what is the effect on the life of the lamp?
following ways?
1. It is increased
1. Lower efficiency and lower temperature 2. It is decreased
2. Lower temperature, which causes higher 3. It depends on the type of lamp
efficiency 4. It remains unchanged
3. Higher temperature, which causes lower
efficiency 4-12. In what way do fluorescent lamps produce light?
4. Higher temperature and efficiency
1. Current causes the electrodes at each end
4-6. Lamps rated at (a) what approximate power are to glow
of the vacuum type because inert gas would 2. Heat from the vaporized mercury causes
have (b) what effect on their luminous output? the phosphor coating to give off light
3. Invisible, short-wave radiation is
1. (a) 50 (b) decrease produced by the discharge through the
2. (a) 60 (b) decrease mercury vapor
3. (a) 50 (b) increase 4. The inductive kick of the ballast causes
4. (a) 60 (b) increase the electrodes at each end to glow

4-7. If you operate a lamp with what (a) respect to 4-13. You are looking at a lamp symbol and see a
its rated voltage, the operation will have (b) black dot inside the symbol. What does this
what effect on the life of the lamp? symbol tell you about the lamp?

1. (a) Higher (b) unchanged 1. It is gas filled

2. (a) Higher (b) decreased 2. It is vacuum sealed
3. (a) Lower (b) decreased 3. The type of phosphorescence used in the lamp
4. (a) Lower (b) unchanged 4. The type of electrode in the lamp

4-8. Which of the following is a type of bulb finish 4-14. You have closed the circuit switch to a
available through the Navy supply system? fluorescent lamp. When does the current start
to flow between the lamp’s electrodes?
1. Inside frosted
2. Silvered bowl 1. Immediately
3. Clear 2. When the glow lamp bimetal strip
4. Each of the above touches the fixed electrode
3. As soon as the bimetal strip is heated by
4-9. Medium-base lamps are commonly used for the glow lamp
what type of illumination? 4. After the starting circuit opens

1. For direct 1,000-watt flood lamps 4-15. Which of the following is the reason for
2. For indirect lighting on lamps rated fluorescent lamps ignition?
between 300 and 500 watts
3. For general lighting on lamps rated at 1. The voltage developed by the collapse of
300 watts or less the ballast magnetic field when the start
4. For detail lighting on three-way lamps circuit opens causes an arc across the
4-10. What type of base is used for incandescent electrodes
lamps rated above 300 watts? 2. The heat of the glow lamp causes the
starter to short circuit the start circuit
1. Mogul 3. The voltage developed in the ballast
2. Medium causes the starter to open and produce an
3. Candelabra arc at the electrodes
4. Intermediate 4. The conduction of the mercury vapor in
the lamp short circuits the ballast
27
4-16. You can operate a fluorescent lamp rated at 4-21. You need to determine whether a 120-volt
120 volts at which of the following voltages lighting fixture is energized by ac or dc. What
without seriously affecting the operation or life means should you use to make this
of the lamp? determination?

1. 95 V 1. A TV lamp
2. 105 V 2. A glow lamp
3. 130 V 3. A fluorescent lamp
4. 150 V 4. An incandescent lamp

4-17. What means should you use to minimize the 4-22. The starting gas used in low-pressure sodium
stroboscopic effect of fluorescent lamps that lamps includes which of the following gases?
arc operating on three-phase ac circuits?
1. Argon
1. Reduce the number of lamps in the circuit 2. Neon
2. Operate the lamps in different circuits on 3. Xenon
different phases 4. All of the above
3. Increase the number of lamps in the
circuit 4-23. What color light is produced by low-pressure
4. Combine two or three lamps in a fixture sodium lamps?
and operate them on different phases
1. Iridescent blue
4-18. You can tell if a fluorescent lamp is defective 2. Diffusible green
by which of the following indications? 3. Monochromatic yellow
4. Magenta red
1. Worn electrodes
2. Blackened ends 4-24. The low-pressure sodium lamp requires what
3. It is too bright amount of time to reach full brilliancy?
4. It is noisy
1. 1 to 5 minutes
4-19. The color of the light produced by a glow lamp 2. 7 to 15 minutes
is determined by the 3. 15 to 30 seconds
4. 30 to 60 seconds
1. inert gas used in the lamp
2. voltage used to operate the lamp 4-25. What type of mechanism, if any, is used to dim
3. type of electrode used the light output of a low-pressure sodium
4. size of the limiting resistor lamp?

4-20. If a glow lamp is operated on alternating 1. A 0- to 1,000-ohm rheostat is placed in

current, when, if ever, is light produced? series with the lamp
2. A 0- to 1,000-ohm rheostat is placed in
1. During a portion of the negative half parallel with the lamp
cycle 3. The supply voltage to the lamp is
2. During a portion of the positive half cycle adjusted
3. During a portion of each half cycle 4. None; the light cannot be dimmed
4. Never

28
4-26. You should not allow a low-pressure sodium 4-30. The number and type of regular permanent
lamp’s internals to come in contact with air for lighting fixtures installed in a compartment for
what reason? general illumination is determined by which of
the following factors?
1. The phosphor coating of the lamp will
oxidize 1. Current
2. Moisture in the air may combine with the 2. Voltage
sodium in the lamp to produce heat and 3. Both 1 and 2 above
hydrogen 4. Light intensity
3. Ethane gas is produced by mixing the
salt-laden air with-the neon gas inside the 4-31. What is the purpose of the phosphor coating in
lamp fluorescent lamps?
4. Phosgene gas is produced if the element
is energized in air 1. To cause the electrodes at each end to glow
2. To cause the heat from the vaporized
4-27. Low-pressure sodium lamps should be stored mercury to make the phosphor coating
in which of the following ways? give off light
3. To produce invisible, short-wave
1. In their original wrapper radiation by the discharge through the
2. Horizontally mercury vapor
3. In spaces with sprinkler systems 4. To absorb the invisible short-wave
4. All of the above radiant energy produced by the lamp and
reradiate it over a band of wavelengths
4-28. You are disposing of a low-pressure sodium visible to the eye
lamp over the side of the ship. Which of the
following protective equipment must you 4-32. What undesirable effect results when
wear? fluorescent lamps are operated on ac circuits?

1. Eye protection 1. A capacitive load on the electrical

2. Protective clothing distribution system
3. A face shield 2. A flicker that may cause a stroboscopic
4. All of the above effect on rotating machinery
3. Excessive heat
4-29. Lighting fixtures are designated according to 4. Excessive current is drawn from the line
which of the following design features? while starting the lamps

1. Size 4-33. In time of war, all topside light must be filtered

2. Color to become red in color.
3. Type of enclosure
4. Illumination 1. True
2. False

4-34. You should use a few drops of ammonia in the

rinse water when cleaning light fixtures for
what reason?

1. To sterilize the fixture

2. To remove the soap film
3. To kill insects that may enter the fixture
4. To remove oily fingerprints

29
 4-39. Forward and after anchor light.
Learning Objective: Recognize the principles of
operation and identify maintenance performed on 1. A
navigational lights. 2. B
3. C
4. D
A. 50-WATT, TWO-FILAMENT
B. 100-WATT, TWO-FILAMENT 4-40. If a ship has the upper and lower red task
C. 15-WATT, ONE-FILAMENT lights burning steadily, what condition is
D. 50-WATT, ONE-FILAMENT indicated?

1. Launching aircraft
Figure 4B. 2. Not under command
3. Man overboard
IN ANSWERING QUESTIONS 4-35 THROUGH 4-39, 4. Minesweeping
REFER TO FIGURE 4B AND SELECT THE LAMP SIZE
FROM THE FIGURE THAT MUST BE REPLACED IN 4-41. When are navigation lights tested at sea?
THE FIXTURE OF THE NAVIGATIONAL LIGHT
USED AS THE QUESTION. 1. Every Friday, at 0700
2. Every 2 hours during the afternoon
4-35. Mast head lights. 3. Every day, about 1 hour before sunset
4. Once a month, according to PMS
1. A requirements
2. B
3. C 4-42. The Grimes light is used for which of the
4. D following ship’s functions?

4-36. Port and starboard side lights. 1. Station marking

2. ASW operation signaling
1. A 3. Identifying stores
2. B 4. Indicating a disabled ship
3. C
4. D 4-43. What is the purpose of station marking
lights?
4-37. White stem light.
1. To identify the stores that are to be sent
1. A to a replenishment station
2. B 2. To identify ships involved in ASW
3. C operations
4. D 3. To help ships maintain their stations in a
convoy
4-38. Man overboard light. 4. To identify lines of departure for
amphibious operations
1. A
2. B
3. C
4. D

30
 Learning Objective: Recognize construction
features of searchlights and identify procedures
for testing, inspecting, cleaning, lubricating,
and repairing them.

4-47. What is the usual location of operating keys

for blinker lights?

1. On the signal bridge

2. In radio central
3. In the pilothouse
4. On the mast

Figure 4C. 4-48. Searchlights are classified by which of the

following means?
IN ANSWERING QUESTIONS 4-44 AND 4-45,
REFER TO THE RUNNING LIGHT CONTROL 1. Their shape and power source
SCHEMATIC DIAGRAM SHOWN IN FIGURE 4C. 2. Their shape and reflector size
3. Their light source arid the size of the
4-44. When the relay of the running light is reflector
deenergized because the primary filament 4. Their light source and their voltage
failed, the relay functions and performs which
of the following actions? 4-49. What is the operating voltage of a transformer-
equipped, 8-inch, scaled-beam searchlight?
1. Sounds the buzzer and moves an
annunciator target to read out 1. 12 V
2. Energizes the indicator light 2. 28 V
3. Transfers power to the secondary 3. 60 V
filament of the affected light 4. 115 V
4. All of the above
4-50. What device holds together the backshell
4-45. While repairing the affected running light, you housing and shutter of an 8-inch, sealed-beam
can silence the buzzer by what means? searchlight?

1. Close contacts X and Y 1. The springs

2. Close contacts Y and Z 2. A swivel-mounted yoke
3. Place the reset switch in the horizontal 3. The rail clamp
position 4. A quick-release clamp ring
4. Place the reset switch in the vertical
position 4-51. What device is installed to align the backshell
housing of the 8-inch, scaled-beam
4-46. What color are the hull contour signal lights? searchlight?

1. Red 1. A yoke
2. Yellow 2. A swivel
3. White 3. A clamp ring
4. Blue 4. A hook and key

31
4-52. Which of the following is the primary use of
the 12-inch incandescent searchlight? Learning Objective: Recognize the
fundamentals of shipboard-diversified lighting
1. Signaling equipment.
2. Illumination
3. Searching
4-58. The use of light traps to prevent a light from
4. Identification
being shown topside is preferred over door
switches when which of the following
4-53. To increase the light intensity and range of
situations exists?
a 12-inch searchlight, a small amount of
what element is added to the lamp by the
1. The possibility exists of exposing light
manufacturer?
from hatches on deck above the
compartment
1. Neon
2. The activities in the compartment must
2. Mercury
be carried on uninterrupted by a lack of
3. Argon
light
4. Xenon
3. The flow of traffic through the
compartment is heavy
4-54. The safety switch of the 12-inch, mercury-
4. Each of the above
xenon searchlight has what total number of
contacts?
4-59. When door switches are connected in series or
in parallel, in what location are lock-in devices
1. One
installed?
2. Two
3. Three
1. On the outer door only in both series and
4. Four
parallel door switch circuits
2. Anywhere in the circuit in both series and
4-55. When the mercury-xenon arc searchlight is
parallel door switch circuits
turned on, what amount of voltage is supplied
3. Any accessible location in a series door
to the spark gap?
switch circuit and on the outer door in a
parallel door switch circuit
1. 25 V
4. Any accessible location in a parallel door
2. 65 V
switch circuit and on the outer door in a
3. 25,000 V
series door switch circuit
4. 50,000 V
4-60. What type of lighting fixtures are provided for
4-56. The mercury-xenon arc lamp starting current is
illuminating crane and hoist areas?
limited by what component?
1. Permanently installed floodlights
1. The RF coil
2. Portable floodlights
2. The feed through capacitor
3. Station marker lights
3. The five parallel-connected resistors
4. Battle lanterns
4. The five series-connected resistors
4-61. The portable, hand-held battle lantern contains
4-57. What material should you use to clean the
what total number of batteries?
reflector of a searchlight?
1. One
1. Standard Navy brightwork polish
2. Two
2. Inhibited methyl chloroform
3. Three
3. Hot water with a few drops of ammonia
4. Four
4. Dry cleaning solvent P-D-680

32
4-62. The portable hand-held, sealed-beam lamp is 4-66. The portable flood lantern has what total
rated at what voltage? number of viewing windows?

1. 6V 1. Eight
2. 5V 2. Two
3. 3V 3. Six
4. 4V 4. Four

4-63. The relay-operated lantern should be installed 4-67. While checking the condition of the battery
in what position? of a portable flood lantern, you discover
that only the red and white balls are
1. With the relay upright floating at the surface of the electrolyte.
2. With the relay at either side What amount of charge does the battery
3. With the relay at the bottom have?
4. With the relay in any position
1. 10%
4-64. Relay-operated lanterns are required to be 2. Between 50 and 90%
installed in all EXCEPT which of the 3. 95%
following spaces? 4. 100%

1. Freezer boxes 4-68. For what specified period of time can

2. Watch stations portable flood lanterns be operated before
3. Machinery compartments the batteries must be recharged?
4. Battle dressing stations
1. 1 hour
4-65. A compartment aboard ship is furnished 2. 7 hours
electrical power from the 220-volt power 3. 3 hours
circuit, the 117-volt ship’s service lighting 4. 5 hours
system, the 117-volt emergency lighting
system, and the 117-volt power circuit.
What circuit should furnish power for the
relay-operated hand lantern?

1. The 220-volt power circuit

2. The 117-volt power circuit
3. The 117-volt emergency lighting system
4. The 117-volt ship’s service system

33
 ASSIGNMENT 5
Textbook Assignment: “Electrical Auxiliaries,” chapter 5, pages 5-1 through 5-73.

5-5. What method should you use to mix

Learning Objective: Recognize the principles electrolyte?
of operation and identify safe working
practices for storage batteries, battery chargers, 1. Heat the water before pouring it into the
and small craft electrical systems. acid
2. Always pour water into the acid
3. Use only aluminum or zinc containers
5-1. The specific gravity of battery electrolyte is the
4. Always pour acid into the water
ratio of what electrolyte components?
5-6. If you want to know the rating of a lead-acid
1. The weight of a specific volume of water
storage battery, you would normally use what
to the weight of the same volume of acid
hourly discharge rate?
2. The weight of a specific volume of acid
to the weight of the same volume of water
1. 25-hour rate
3. The weight of acid to the temperature of
2. 20-hour rate
water
3. 10-hour rate
4. The temperature of water to the
4. 6-hour rate
temperature of acid
5-7. An equalizing charge on a battery is continued
5-2. On a small boat, what is the adjusted specific
for 4 hours until which of the following
gravity of a fully charged battery?
conditions is met?
1. 1.000 to 1.830
1. The terminal voltage shows no change
2. 1.150 to 1.460
2. The charging current shows no change
3. 1.210 to 1.220
3. The specific gravity of all cells shows no
4. 1.400 to 1.600
change
4. The temperature of all cells exceeds
5-3. What is the corrected specific gravity reading
125°F
for a battery whose electrolyte temperature is
89°F and has an uncorrected reading of 1.212?
5-8. Which of the following battery conditions may
be caused by a high charging rate?
1. 1.200
2. 1.210
1. Excessive gassing
3. 1.215
2. Sulfated plates
4. 1.220
3. Inverse electrolysis
4. Reverse polarization
5-4. What is the corrected specific gravity reading
for a battery whose electrolyte temperature is
5-9. You have spilled battery acid on your arm.
74°F and has an uncorrected reading of 1.220?
What is the first step you should take?
1. 1.218
1. Sprinkle baking soda on the area
2. 1.216
2. Cover the area with boric acid powder
3. 1.214
3. Wash the area thoroughly with fresh
4. 1.212
water
4. Spread a thin coating of petroleum jelly
over the area

34
IN ANSWERING QUESTIONS 5-10 AND 5-11, 5-14. On a starting motor, what causes the pull-in
REFER TO FIGURE 5-4 IN YOUR TEXTBOOK. coil to de-energize once the solenoid switch is
closed?
5-10. The output of the battery charger is determined
by what component(s)? 1. The solenoid plunger opens the coil
contacts
1. Switch S2 2. The holding coil closes auxiliary contacts
2. Switch S3 in the start circuit
3. The SCRs 3. The start motor terminals are opened,
4. Resistor R4 shorting the pull-in coil
4. The pull-in coil is shorted by the plunger
5-11. What component compensates for temperature disk closing the start contacts
changes?

1. Resistor R4 Learning Objective: Identify the way ship’s

2. Resistor R5 air compressor and air-conditioning and
3. Zener diode CR13 refrigeration systems operate.
4. Control coil L1
5-15. The low pressure air compressor has what total
5-12. What action should you take to prevent a small
number of modes of operation?
boat motor from overheating?
1. One auto and two manual (low and high)
1. Operate the starting motor for 30-second
2. Two auto (low and high) and one manual
periods at 2-minute intervals
3. One manual and three auto (low, medium,
2. Operate the starting motor for a
and high)
maximum of 2-minute periods at 30-
4. Two manual (low and high) and two auto
second intervals
(low and high)
3. Continue the operation of the starting
motor after the drive pinion engages the
5-16. On an air compressor, what condition is
flywheel
indicated by the enable running light?
4. Intermittently operate the starting motor
for about 2 minutes, and, if the engine
1. Power is available to the compressor
fails to start, allow the motor to cool
2. The compressor is in the automatic mode
before trying again
3. The dew point is at a safe level
4. The compressor is in an operative
5-13. What is the ratio of the speed of the starting
condition
motor to that of the engine?
5-17. What compressor component operates to allow
1. 150 to 1
the flow of the injection water?
2. 15 to 1
3. 2 to 1
1. Servo valve SV1
4. 1 to 1
2. Timing relay 6TR
3. Control relay 1CR
4. Pressure switch PS1

5-18. When operating in the automatic 125 setting,

the compressor is set to (a) start and (b) stop at
what pressure?

1. (a) 105 psig rising (b) 120 falling

2. (a) 110 psig rising (b) 125 psig falling
3. (a) 105 psig falling (b) 120 psig rising
4. (a) 110 psig falling (b) 125 psig rising

35
5-19. What compressor component operates to drain 5-24. The oil pressure safety switch is designed to
the dehydrator condensate sump? secure the refrigeration compressor if the oil
pressure drops to what minimum value?
1. Solenoid valve SV7
2. Timing relay 3TR 1. 24 psi
3. Selector switch 1SEL 2. 22 psi
4. Control relay 16CR 3. 18 psi
4. 12 psi
5-20. What component acts to delay compressor
shutdown for 10 minutes once a discharge 5-25. What type of controller is used on the air-
pressure of 125 psig is reached? conditioning system?

1. Pressure switch PS1 1. LVP

2. Timing relay 1TR 2. LVR
3. Selector switch 1SEL 3. LVRE
4. Undervoltage relay UV 4. LVCR

5-21. Freeze storerooms and chill storerooms are IN ANSWERING QUESTIONS 5-26 THROUGH 5-29,
maintained at what temperature, respectively? REFER TO FIGURE 5-10 IN YOUR TEXTBOOK.

1. 32°F and 40°F 5-26. What is the purpose of the heater in the control
2. 0°C and 33°C circuit?
3. 33°F and 0°F
4. 0°F and 33°F 1. To keep the ambient temperature above
freezing to prevent sluggish operation of
5-22. What is the purpose of the elapsed time meter? the compressor
2. To keep the oil of the compressor warm
1. To keep track of the time a compressor is 3. To prevent condensation from forming in
operated the compressor motor windings
2. To operate timed contacts at precise set 4. To keep the control circuitry from
points freezing
3. To prevent equipment from being
overused between overhauls 5-27. The suction pressure switch SP is set to
4. To allow operators to set the equipment (a) open and (b) close at what pressure?
to start and stop automatically
1. (a) 5 in.Hg (b) 8 psig
5-23. On a refrigeration system, timing relays 2. (a) 5 in.Hg (b) 5 psig
provide what safety feature? 3. (a) 8 in.Hg (b) 8 psig
4. (a) 8 in.Hg (b) 5 psig
1. Prevent overloading the refrigeration
compressor 5-28. What voltage is used to operate the
2. Secure the refrigeration after 10 seconds components of the control circuit?
if no oil pressure develops
3. Prevent the unit from operating if there is 1. 440 Vac
no water 2. 120 Vac
4. Secure the controller if there is a loss of 3. 110 Vac
voltage 4. 28 Vac

36
5-29. What is the purpose of timing relay TR? 5-33. The tank of the ultrasonic cleaner has what
total number of sections?
1. It closes after a 10-second time delay to
de-energize the compressor if water 1. One
pressure has not caused water pressure 2. Two
switch W to close its contacts 3. Three
2. It inserts a 10-second time delay between 4. Four
the time the compressor is energized and
suction pressure switch SP becomes 5-34. What principle permits the ultrasonic cleaner
active to operate with very little loss of strength?
3. It opens after a 10-second time delay to
de-energize the compressor if oil pressure 1. The relative incompressibility of all
has not caused oil pressure switch OP to liquids
close its contacts 2. The size of sound waves
4. It prevents short circuiting the 3. The temperature of the cleaning medium
compressor motor by inserting a time 4. The frequency of the sound waves
delay on start up
5-35. What principle is the basis for the operation of
the vent fog precipitator?
Learning Objective: Identify the basic
operating procedures for pendulum window 1. The inversion square law
wipers, portable welders, ultrasonic cleaners, 2. Kirchoff’s law
and electrostatic precipitators. 3. Ohm’s law
4. Electrostatic precipitation
5-36. What safety feature is incorporated into a
5-30. What voltage is used to operate the wiper
precipitator to prevent electrical shock to the
motor?
operator?
1. 68 to 115 Vdc
1. The primary is fused
2. 115 Vac
2. The surge limiting resistor
3. 220 Vdc
3. The secondary is grounded
4. 440 Vac
4. The access cover safety switch
5-31. What are the three major components of a
window wiper? Learning Objective: Identify the basic
operation of the propulsion shaft
1. Drive unit, load monitor, and wiper arm torsionometer.
2. Control box, rectifier unit, and drive unit
3. Load monitor, drive unit, and wiper arm
4. Control box, drive unit, and wiper arm 5-37. What is the purpose of the shaft torsionometer
system?
5-32. What feature de-ices the window served by the
wiper? 1. To measure the torque on the propulsion
shaft
1. Heaters placed on the bulkhead next to 2. To prevent the shaft from being
the window overstressed
2. A wire-wound resistor placed in the 3. To allow precise shaft speeds to be
control box maintained
3. A 36-watt heating element in the wiper arm 4. To determine the optimum screw blade
4. The friction of the blades on the window angle for maximum efficiency

37
5-38. By what means are shaft hp readings displayed 5-43. What elevator component slows the elevator
in remote areas of the ship? once it reaches the desired level?

1. Torque 1. The limit switches insert resistance in the

2. Repeaters only motor circuit
3. Remote displays only 2. The photo sensors engage the brake
4. Repeaters and remote displays 3. A cam-operated limit switch switches the
motor to a lower speed just before the
desired level
Learning Objective: Recognize the basic 4. The reduction gear coupling disengages
theory of operation of various pieces of deck
equipment, including winches, elevators,
UNREP systems, and electric forklifts. A. LOCATED AT EACH LEVEL SERVED;
USED TO STOP THE ELEVATOR IN AN
EMERGENCY
5-39. The magnetic brakes of the electric anchor B. STOPS THE ELEVATOR IF IT SHOULD
windlass provide what safety feature? FAIL TO STOP AT THE UPPERMOST
LEVEL
1. A positive engagement/disengagement of C. STOPS THE MOTOR TO PROTECT IT
the reduction gears FROM AN OVERCURRENT CONDITION
2. Remote operation of the brake
D. PREVENTS ELEVATOR OPERATION IF
3. Prevent overspeed
THE CABLES BECOME LOOSE
4. Hold the load if power fails

5-40. What is the purpose of the controlled torque Figure 5A.

coupling?
MATCH THE PROTECTIVE FEATURES IN
1. To control the speed of the windlass QUESTIONS 5-44 AND 5-45 WITH THEIR PURPOSE
when dropping anchor IN FIGURE 5A.
2. To ensure constant torque on the gypsy
head 5-44. Motor overloads.
3. To prevent excessive stresses when the
anchor is being housed 1. A
4. To disconnect the windlass motor from 2. B
power if there is an overload 3. C
4. D
5-41. If the power fails when the anchor and chain
are being lowered, the electric brake is 5-45. Slack cable switch.
designed to hold what percentage of the rated
load? 1. A
2. B
1. 250 % 3. C
2. 225 % 4. D
3. 200 %
4. 150 % 5-46. In electrohydraulic elevators, speed changes
are accomplished by what means?
5-42. The capstan is designed to heave (a) what line
at (b) what speed? 1. Using a variable resistor in the control
circuit
1. (a) 8-inch (b) 50 feet/minute 2. Varying the stroke of the hydraulic pump
2. (a) 6-inch (b) 150 feet/minute 3. Altering the hydraulic oil pressure to the
3. (a) 8-inch (b) 150 feet/minute pump
4. (a) 6-inch (b) 50 feet/minute 4. Altering the reduction gear coupling ratio

38
5-47. Elevators are prevented from being operated 5-52. What arc the two major units of the UNREP
from more than one location by the installation system?
of what component(s)?
1. Sending and control
1. Interlocked pushbutton stations 2. Control and receiving
2. Limit switches 3. Control and monitoring
3. Emergency-run switches 4. Sending and receiving
4. Door mechanical interlocks
5-53. What is the purpose of the ram tensioner?
5-48. If an elevator platform overtravels in the down
direction, which of the following devices helps 1. To keep the wire rope from tangling on
to prevent damage to the platform and the hull? the UNREP winches
2. To prevent the highline winches from
1. Spring bumpers paying out too much wire
2. Electric brakes 3. To help the highline winch operator keep
3. Safety clamps the highline tight during UNREP
4. All of the above operations
4. To return the empty trolley to the delivery
5-49. The functions performed in electric elevators ship
by limit switches, relays, and contractors are
performed in electronically controlled 5-54. Which of the following are components of the
elevators by what component(s)? receiving unit of the receiving ship?

1. The sensing heads 1. A chain hoist, worm gear, arm rotation

2. The cam targets motor, and king post winches
3. The motor controller 2. A king post, a receiving head, an elevator,
4. The static logic panel a carriage return unit, and a remote
control console
5-50. What advantage, if any, is gained by using a dc 3. A king post, a receiving head, an arm
motor as the pilot motor? rotation motor, and king post winches
4. An elevator, king post winches, a chain
1. The dc pilot motor operation is hoist, a remote control unit, and an arms
economical rotation motor
2. The dc pilot motor is simple to operate
and requires little maintenance 5-55. Which of the following are components of
3. The dc pilot motor makes an infinite the steer motor power circuit in an electric
number of platform speeds available, forklift?
which range from 3 to 90 feet per minute
4. None 1. The drive motor and its series field
2. An electric motor, hoist and tilt cylinders,
5-51. Which of the following is the purpose of the and a directional control value
sensing heads mounted up and down the 3. The steering motor and contacts of the
elevator trunk? steer relay coil (S)
4. The lift pump motor and contacts of the
1. To slow and stop the elevator pump relay coil (P)
2. To prevent the elevator from
overspeeding
3. To prevent overtravel
4. Each of the above

39
5-56. What is the advantage of using solid-state 5-61. What is the most common cause of failure in
control circuitry integrated with magnetically any hydraulic system?
operated devices to regulate the speed of the
series driven motor in an electric forklift? 1. Excessive use
2. Low oil pressure
1. Enables the generator to handle heavy 3. Dirty oil
loads at slow speeds with large battery 4. Loss of power
currents
2. Allows longer battery-powered operation
A. PROVIDES RUDDER POSITION
before recharging is needed
INFORMATION TO OPERATORS
3. Prevents damage to the control circuitry
from power fluctuations B. PROVIDES A MECHANICAL INDICATION OF
4. Enables the control circuitry to operate THE RUDDER COMMAND POSITION
under higher current conditions C. PROVIDES A NONVERBAL MEANS OF
COMMUNICATING RUDDER COMMANDS
5-57. In a forklift, thermal switches serve to protect FROM THE PILOTHOUSE TO THE STEERING
the drive and steer motor circuits by opening if GEAR ROOM
what minimum motor frame temperature is D. PROVIDES THE OPTION OF STEERING FROM
reached? EITHER THE PORT OR STBD BRIDGE WING

1. 225°F
Figure 5B.
2. 230°F
3. 245°F
IN ANSWERING QUESTIONS 5-62 THROUGH 5-65,
4. 250°F
MATCH THE TERM USED AS THE QUESTION
WITH ITS DEFINITION SHOWN IN FIGURE 5B.
Learning Objective: Identify the purpose and
basic operating fundamentals of the ship’s 5-62. Rudder angle display system.
steering system and its associated equipment.
1. A
2. B
5-58. Where is the ship’s control console located? 3. C
4. D
1. The after steering room
2. The auxiliary control room 5-63. Portable steering control unit.
3. The pilothouse
4. The main engineering space 1. A
2. B
5-59. The rudders have a maximum working angle 3. C
of what number of degrees (a) left and (b) right 4. D
from the middle ship’s position?
5-64. Helm wheel angle indicator.
1. (a) 35 (b) 38
2. (a) 35 (b) 35 1. A
3. (a) 38 (b) 38 2. B
4. (a) 38 (b) 35 3. C
4. D
5-60. Which of the following means can be used to
control the operation of the steering gear? 5-65. Rudder angle order system.

1. Hand electric 1. A
2. Autopilot 2. B
3. Emergency control 3. C
4. Each of the above 4. D

40
 5-70. What is the normal dry weight load capacity of
Learning Objective: Identify the operation the washer extractor?
and maintenance of electric galley and
laundry equipment. 1. 35 pounds
2. 53 pounds
3. 60 pounds
5-66. Which of the following electric galley ranges
4. 100 pounds
are currently used?
5-71. What means is used to operate the brake and
1. Type A, 36 inches
clutch assemblies?
2. Type B, 20 inches
3. Type C, 30 inches
1. Ship’s service compressed air
4. Each of the above
2. Hydraulic fluid under pressure
3. Friction of the reduction gears
5-67. What is the most common type of convection
4. Water pressure from the ship’s fresh
oven used aboard ship?
water system
1. Type 10
5-72. When is the automatic injection system used?
2. M-series
3. Series 60
1. During MANUAL mode
4. Model 250
2. During FORMULA mode
3. During COMMAND mode
5-68. What is the heating range of the electric
4. During an imbalance situation
griddle?
5-73. The washer extractor should always be loaded
1. 380 to 475°F only
to capacity before operating for what reason?
2. 375 to 600°F
3. 350 to 450°F only
1. To save power
4. 200 to 450°F
2. Lighter loads place undo wear on the
machine
5-69. What is the most frequent trouble with electric
3. To prevent possible damage to items
cooking equipment in the galley?
being washed
4. Lighter loads may fail to distribute the
1. Burnt contacts
clothes properly
2. Open thermostats
3. Loose connections
4. Improperly set thermostats

41
 ASSIGNMENT 6
Textbook Assignment: “Motor Controllers,” chapter 6, pages 6-1 through 6-24.

6-5. What is the major advantage of the closed

Learning Objective: Recognize the operating transition transformer over the open transition
characteristics of protective and operative transformer?
components of controllers. Identify
adjustments that can be made on controllers. 1. It’s smaller in size; therefore, it’s cheaper
and lighter
2. The motor can’t slip out of phase during
6-1. What are the two general methods of starting
the transition phase
motors electromagnetically?
3. It has fewer moving parts, making it less
susceptible to breakdown
1. Manually and automatically
4. It has higher transition current; therefore,
2. Across-the-line and reduced voltage
it allows the motor to maintain speed
3. Across-the-line and manually
during the transition phase
4. Accelerating and reduced voltage
6-6. Which of the following is a disadvantage of an
6-2. By what means are the contactors of a
open transition compensator?
magnetic controller operated?
1. The motor may slip into phase during
1. By electromechanical devices
transition, causing an overload
2. By a remote control master switch
2. The resistor dissipates too much heat
3. By a locally controlled master switch
3. The wound rotor has a tendency to
4. Each of the above
overspeed
4. The motor may slip out of phase during
6-3. What type of controller is used to start a 1/4-hp
transition, causing an overload
dc motor?
6-7. By what means is the designation of a
1. A dc across the line motor controller
magnetic controller shown?
2. A static variable-speed controller
3. An ac primary resistor
1. Alphabetically, according to the
4. An autotransformer
minimum horsepower rating of the
connected load
6-4. What type of controller is used to insert
2. Numerically, according to the maximum
resistance in the secondary circuit of a wound
horsepower rating of the connected load
rotor motor?
3. By the amount of current at which the
controller is capable of operating safely
1. An ac secondary resistor
4. By the maximum horsepower rating of
2. A dc secondary resistor
the connected load
3. An ac primary resistor
4. An autotransformer
6-8. You are installing a new 450-volt, three-phase
motor and controller according to a ship
alteration. If the motor is rated at 15 hp, you
should use what size controller?

1. 1
2. 2
3. 3
4. 0

42
6-9. What type of controller enclosure provides the 6-14. When the energized contacts in an ac contactor
least amount of ventilation to the internal are opened, what method is used to quench the
components? arc that is created?

1. Open 1. Blowout coils dissipate the arc

2. Spraytight 2. An air gap dissipates the arc
3. Watertight 3. Shading bands cause the arc to scatter and
4. Submersible disappear
4. The inductive reactance of the coil
6-10. If a master switch is mounted in the controller, dissipates the arc
it is classified as what type of switch?
6-15. What factor allows ac contactor coils to be
1. Local smaller than dc coils rated for the same
2. Remote voltage?
3. Momentary
4. Maintaining 1. AC doesn’t cause as much current as dc
2. AC coils are constructed of different
6-11. What is the purpose of arcing contacts? types of wire
3. DC causes more internal heat to be built up
1. To allow auxiliary contacts to cool off 4. Inductive reactance causes counter-emf to
2. To reduce the amount of arcing at the limit current flow in an ac coil
main contacts when opening or closing
3. To prevent arcing in the contactor during
opening and closing Learning Objective: Recognize the operating
4. To energize auxiliary loads when the fundamentals on an ac motor controller.
contactor closes
6-16. A controller protecting a motor is able to
6-12. What method, if any, should you use to keep
disconnect it from the power supply, keep it
arcing contacts clean?
disconnected, and then restart it automatically
when conditions return to normal. Which of
1. Wipe them with inhibited methyl
the following forms of protection is the
chloroform
controller providing?
2. File them with a very fine file, then wipe
them with a clean, soft cloth
1. Overload
3. Clean them with standard Navy
2. Low voltage
brightwork polish
3. Low-voltage release
4. None; they are self-cleaning
4. Each of the above
6-13. By what means do magnetic blowout coils
quench the arc across contacts?
6-17. Shunt contractors will handle up to what
(a) current at what (b) voltage?
1. By increasing the contact separation
2. By providing a magnetic flux that blows
1. (a) 700 A (b) 120 V
out the arc
2. (a) 600 A (b) 230 V
3. By opposing the current flow
3. (a) 700 A (b) 230 V
4. By pulling the arc toward the contacts
4. (a) 600 A (b) 120 V

6-18. What material is used to construct the arcing

contacts of a dc controller?

1. Copper manganese
2. Cadmium with a coating of copper
3. Silver oxide
4. Copper with a heavy coating of cadmium

43
 6-23. What means is used to determine the speed of
ac squirrel cage induction motors?

1. The value of voltage supplies

2. The amount of current through the rotor
3. The speed of the rotating magnetic field
4. The resistance of the stator winding

6-24. What means should you use to change the

Figure 6A. speed of an ac motor through the controller?
IN ANSWERING QUESTIONS 6-19 THROUGH 6-21,
1. Change the connections to the motor
REFER TO THE AC CONTROLLER SHOWN IN
2. Change the resistance in the starting
FIGURE 6A.
circuit
6-19. What forms of protection are provided by the 3. Vary the line frequency
magnetic controller? 4. Step up the supply voltage

1. Low-voltage and low-voltage release only 6-25. One type of a motor speed controller controls
2. Low-voltage and overload only the speed of the ac motor by performing which
3. Low-voltage release and overload only of the following actions?
4. Low-voltage release, low-voltage, and
overload 1. Increasing and decreasing stator current
2. Switching from one set of stator windings
6-20. You push the button that starts the motor. After to another
you release the start button, what contact closes 3. Increasing and decreasing the voltage of
to complete a holding circuit for energizing the the power source
contactor coil? 4. Shunting different values of resistance
across the stator windings
1. M1
2. M2 6-26. What means is used to determine the speed of
3. M3 dc motors?
4. MA
1. The number of poles in the armature
6-21. To reverse the direction of rotation of the 2. The amount of current flowing through
motor, the controller must be capable of the field and armature windings
performing which of the following functions? 3. The direction of current flow through the
field windings
1. Disconnecting L2 from T2 4. The frequency of the applied voltage
2. Disconnecting L1 from T1 or L3 from T3
3. Connecting L1 to T3 and L3 to T1 6-27. A reversing type of controller protects a three-
4. Closing MA at the same time that M1, phase induction motor against low voltage and
M2, and M3 are closed overload by causing the motor to stop running
due to line voltage failure. After line voltage
6-22. What is the major difference between an LVR is restored, what action, if any, should you
and an LVRE controller? perform to restart the motor?

1. The LVRE does not use a coil in its 1. Press the forward or reverse push buttons
circuit to operate the contacts 2. Reset the overloads and press the forward
2. The LVR has no auxiliary contact to and reverse push buttons simultaneously
maintain the circuit across the start switch 3. Interchange two of the three leads to the
3. The LVRE doesn’t use overload contacts motor
in series with the operating coil 4. None; the motor automatically restarts
4. The LVR doesn’t need to be manually
reset upon loss of normal line voltage
44
 6-32. What is the most common method used to
reverse the direction of rotation of a dc motor
through a controller?

1. Reversing the rotation of the rotating

magnetic field
2. Reconnecting the brush leads to place the
brushes in series
3. Reversing the connections of the field
with respect to the armature
4. Reversing the connection of the armature
with respect to the field
Figure 6B.
6-33. Three-phase autotransformers are used to start
IN ANSWERING QUESTIONS 6-28 THROUGH 6-31,
three-phase induction motors and synchronous
REFER TO THE DC CONTROLLER WITH ONE
motors because they have the ability to
STAGE OF ACCELERATION SHOWN IN FIGURE 6B.
perform what function?
6-28. If the start button is pressed, what action will
cause line contacts LC1 and LC2 to close? 1. Furnish variable voltage
2. Reverse the direction of rotation of the
1. Closing line contacts LC4 motor rotor
2. Operation of contactor coil LC 3. Switch motor stator connections from
3. Operation of overload relay coil OL wye to delta
4. Current flowing through armature A and 4. Switch motor stator connections from
contacts LC3 delta to wye

6-29. After closing contacts LC1, LC2, and LC3, the 6-34. By tapping an autotransformer, it is possible to
controller accelerates the motor. By what obtain a voltage higher than the source voltage.
means does the controller connect the motor
across the line? 1. True
2. False
1. By the SR contact completing the circuit
to coil AC 6-35. What is the most common application of logic
2. By contact AC2 shorting out the starting controllers aboard ship?
resistor
3. By allowing coil SR to restore, closing 1. Fractional horsepower motors
the SR contact 2. Propulsion motor control
4. Each of the above 3. Elevator control
4. AC governor control system
6-30. After the motor is connected directly across the
line, what should you do to interrupt the circuit? 6-36. Logic devices and controllers have what
advantage over standard electrical
1. Press the stop button components?
2. Press the start-emergency button
3. Short out the series relay coil 1. They have a quicker response
4. Short out the starting resistor 2. They don’t have any moving parts
3. They consume less power
6-31. To vary the speed of the motor, what action 4. All of the above
should you take to change the controller circuitry?

1. Disconnect SR-relay SR
2. Disconnect the shunt field winding
3. Connect a rheostat in series with the SH winding
4. Connect a rheostat in parallel with the AC coil
45
6-37. In a magnetic circuit breaker, what circuit is 6-41. A heat-sensitive element that lengthens when
opened by an overload relay? heated to open the contacts is used in what
type of thermal overload relay?
1. The main contacts
2. The master switch 1. B
3. The operating coil of the high-speed 2. C
contactor 3. D
4. The operating coil of the main contactor 4. E
6-42. What type of thermal overload relay is
6-38. Which of the following is a coarse adjustment manufactured for exclusive use in ac circuits?
to the thermal overload relay?
1. A
1. Changing the heater element 2. B
2. Changing the magnetic air gap 3. C
3. Increasing the distance between the heater 4. D
and the sensitive unit
4. Decreasing the distance a bimetallic strip 6-43. In relation to the starting current of the motor
has to move to open the circuit they serve, the tripping current of the magnetic
overload relay must be set in what way?
6-39. The tripping current of magnetic overload
relays must be set higher than the starting 1. Higher than the starting current
current of the motor they serve. 2. Lower than the starting current
3. The same as the starting current
1. True 4. 1/4 the starting current
2. False
6-44. In the instantaneous and time-delay magnetic
overload relays, you should use what method
A. BIMETAL
to adjust the current settings?
B. DASHPOT
C. INDUCTION 1. Replace the heating unit
D. SOLDER POT 2. Change the air gap between the tripping
E. SINGLE METAL armature and the series coil
3. Change the distance between the
induction coil and the tube
Figure 6C. 4. Change the distance between the heater
and the heat-sensitive unit
IN ANSWERING QUESTIONS 6-40 THROUGH 6-42,
REFER TO THE TYPES OF OVERLOAD RELAYS 6-45. Which of the following types of overload
SHOWN IN FIGURE 6C. relays requires a time delay before it is reset?

6-40. Of the relays shown in figure 6C, which one is 1. Dashpot

NOT a type of thermal overload relay? 2. Magnetic
3. Solder pot
1. A 4. Each of the above
2. B
3. C
4. D

46
 Figure 6D.

IN ANSWERING QUESTIONS 6-46 AND 6-47,

REFER TO FIGURE 6D.

6-46. The emergency run switch bypasses or shunts

which of the following components? Figure 6E.
IN ANSWERING QUESTIONS 6-48 THROUGH 6-50,
1. The stop switch REFER TO THE THREE-PHASE MAGNETIC LINE
2. The interlock of the main contactor STARTER SHOWN IN FIGURE 6E.
3. The overload contacts
4. The control circuit fuse 6-48. If a voltage is read at position A and no
voltage is present at position B, which of the
6-47. Short-circuit protection to the motor and following statements is true?
controller is provided by which of the
following devices? 1. The voltmeter is defective
2. All fuses are good
1. The circuit breaker at the power 3. The L1 fuse is defective
distribution panels 4. The L2 fuse is defective
2. The fuses at the power distribution panels
3. The controller circuit fuses 6-49. After the start button is released, the motor
4. The overload relays immediately stops. What is the probable cause?

1. The holding relay is open

2. The power contacts on L1 did not close
3. The holding relay contacts MA did not close
4. The OL1 is defective

6-50. With the stop button open and the start button
depressed, what voltage will be present
between points B and D?

1. 440 V
2. 220 V
3. 110 V
4. 0V
47
 A. INSUFFICIENT TIP PRESSURE
B. BROKEN SHADING COIL
C. MECHANICALLY DAMAGED
D. EXCESSIVE JOGGING

Figure 6F.

IN ANSWERING QUESTIONS 6-51 THROUGH

6-53, REFER TO FIGURE 6F, AND SELECT THE
DEFINITION FOR THE SYMPTOM USED AS
THE QUESTION.

6-51. Overheated contact tips.

1. A
2. B
3. C
4. D

6-52. Short contact life.

1. A
2. B
3. C
4. D

6-53. Coil failure (not overheated).

1. A
2. B
3. C
4. D

48
 ASSIGNMENT 7
Textbook Assignment: “Maintenance and Repair of Rotating Electrical Machinery,” chapter 7, pages 7-1
through 7-49.

7-5. Which of the following is NOT a cleaning

Learning Objective: Identify proper cleaning solvent you should use when cleaning
methods for motors and generators. electrical equipment?

1. Inhibited methyl chloroform

7-1. The main objectives of shipboard preventative
2. Alcohol
maintenance are to prevent all EXCEPT which
3. Clean fresh water
of the following situations?
4. Low-pressure air
1. Motor controller malfunctions
2. Cable insulation from having a low Learning Objective: Identify the types, care
resistance of, and insulation methods for motor
3. Generators from being synchronized out generator bearings.
of phase
4. Motor bearing failure
7-6. What type of bearing is designed to support
7-2. The accumulation of dirt, moisture, and oil in loads resulting from forces that are applied
generator and motor ventilation ducts causes perpendicular to the shaft?
local or general overheating for what reason?
1. Thrust
1. The resistance to the dissipation of heat is 2. Radial
decreased 3. Sleeve
2. The resistance to the dissipation of heat is 4. Angular
increased
3. Moisture and dirt form a nonconducting 7-7. In motor construction, what factor determines
paste whether a thrust or radial bearing is installed?
4. Oil and dirt form a nonconducting paste
1. Whether the bearing housing is or is not
7-3. If you need to find the detailed procedures for disassembled to renew bearing grease
cleaning electrical machinery, you should refer 2. Whether the drain holes on the bearing
to what chapter of the NSTM? housing are accessible
3. Whether the motor is mounted vertically
1. 090 or horizontally
2. 220 4. Whether the rotor has clockwise or
3. 244 counterclockwise rotation
4. 300
7-8. In operating machinery, you should suspect
7-4. You are blowing dust from a 75-KW generator malfunctioning ball bearings if which of the
using compressed air. What means should you following g symptoms occurs?
use to remove the dust-laden air from the
generator? 1. A loss of speed
2. Arcing brushes
1. A vacuum cleaner 3. A high temperature
2. Compressed air pressure of less than 30 psi 4. All of the above
3. A suction blower placed at the opening
opposite the air jet
4. A suction hose placed at the same
opening as the air jet
49
7-9. You are starting a motor. You can expect 7-14. When cutting a seized bearing from a shaft,
serious bearing problems if high temperatures you should be careful to cut only 3/4 of the
are reached within what specified amount of way through the inner ring. What is the reason
operating time? for this precaution?

1. 50 to 60 minutes 1. To prevent loss of bearing internals

2. 30 to 40 minutes 2. To prevent damaging the shaft
3. 20 to 25 minutes 3. To prevent personal injury from flying parts
4. 10 to 15 minutes 4. To prevent overheating the bearing journal

7-10. When grease cups for a motor aren’t used to 7-15. When bearings are replaced on a shaft, the
grease bearings, where should they be kept? pressure should be applied to which of the
following locations?
1. In the custody of the responsible
maintenance personnel 1. The bearing inner race
2. In the custody of the chief engineer 2. The bearing outer race
3. On a wire attached to the motor 3. Both 1 and 2 above
4. On a wire attached to a pipe plug 4. The bearing oil seal

7-11. Of the following motors, which one can you grease 7-16. You are using the infrared method for
without disassembling the bearing housing? mounting a motor bearing. The bearing
temperature should NOT exceed which of the
1. A vertically mounted motor following temperatures?
2. A fire pump motor with an accessible
drain hole 1. 100°F ±10°
3. A motor-driven winch without a clutch 2. 150°F ±10°
4. A fan motor without an accessible drain hole 3. 175°F ±10°
4. 203°F ±10°
7-12. In the absence of other instructions, at what
specified level should you maintain the oil in 7-17. Because of grease deterioration or
an oil-lubricated, ball-bearing motor housing? contamination, which of the following
methods of mounting bearings is undesirable?
1. Level with the center of the bearing
2. Level with the top of the bearing 1. The oven method
3. Almost level with the bearing inner ring 2. The hot-oil method
at the lowest point 3. The infrared method
4. Almost level with the bearing inner ring 4. The arbor-press method
at the highest point
7-18. Which of the following types of bearings are
7-13. To prevent damage to a bearing that you are used on large propulsion generators and
pulling, you should place the bearing puller on motors?
the shaft and what other assembly?
1. Rolling
1. The oiler ring 2. Journal
2. The outer race 3. Right line
3. The inner race 4. Tapered rolling
4. The shield

50
7-19. The sleeve bearings of a motor overheat. As a
watch stander, what action should you take? Learning Objective: Identify maintenance procedures
used for brushes, commutators, and slip rings.
1. Stop the motor without securing the load
2. Stop the motor immediately after 7-24. Which of the following factors determines the
securing the load grade of brush used in a motor or generator?
3. Secure the load and let the motor run until
the bearing cools 1. The time in service
4. Continue to run the motor at the rated 2. The size of the motor or generator
load until the bearing cools 3. The load and speed of the motor or generator
4. All of the above
A. ANGULAR CONTACT BEARING 7-25. At what point should you install new brushes
B. RADIAL BEARING in a generator or motor?
C. THRUST BEARING
D. SLEEVE BEARING 1. When the brushes have enclosed shunts
2. When the brushes have a polished surface
Figure 7A. 3. When the brushes are worn to within 1/8
inch of the metallic parts
IN ANSWERING QUESTIONS 7-20 THROUGH 7-23, 4. When the brushes polarity is reversed
REFER TO FIGURE 7A.
7-26. What method should you use to calculate brush
7-20. What type of bearing is designed to support pressure?
loads resulting from forces that are applied
perpendicular to the shaft? 1. Subtract the spring pressure from the
brush contact area
1. A 2. Subtract brush contact area from the
2. B spring pressure
3. C 3. Divide the brush contact area by the
4. D spring pressure
4. Divide the spring pressure by the brush
7-21. What bearing is used when the load is contact area
completely axial?
7-27. When seating a brush, you should use
1. A sandpaper and what other equipment?
2. B
3. C 1. A file
4. D 2. A brush seater
3. An oilstone
7-22. What type of bearing is used in an application 4. Emery paper
where there are radial and thrust loads?
7-28. When seating a brush, you should place the
1. A sandpaper between the brush and the commutator
2. B with the rough side toward (a) what component
3. C and (b) pull in what direction?
4. D
1. (a) The brush
7-23. What bearing types are examples of (b) in the direction of rotation
antifriction bearings? 2. (a) The commutator
(b) opposite the direction of rotation
1. A and B only 3. (a) The commutator
2. A, C, and D only (b) in the direction of rotation
3. B and C only 4. (a) The brush
4. A, B, and C (b) opposite the direction of rotation
51
 7-33. To complete the job of seating the motor
A. USE NO. 0 SANDPAPER
brushes, you should perform which of the
B. USE THE BRUSH SEATER AT THE following steps?
HEEL OF THE BRUSH
C. USE NO. 1 SANDPAPER 1. Pull a fine strip of sandpaper between the
D. VACUUM THE CARBON DUST brush and commutators once or twice,
FROM THE COMMUTATOR vacuum the dust that results, and clean
E. VACUUM THE WHITE POWDER the commutator
FROM THE BRUSH HOLDERS 2. Turn the sandpaper over, sandpaper
AND WINDINGS again, and touch the seater to the heel of
the brush for 1 or 2 seconds
3. Touch the seater to the commutator for 1
Figure 7B. or 2 seconds, vacuum the dust that
results, and clean the commutator
IN ANSWERING QUESTION 7-29, REFER TO 4. Lift the brush, insert the seater between
FIGURE 7B. the brush and commutator for 1 or 2
seconds, and clean the commutator
7-29. Of the sequences shown below select the
proper one for seating brushes. 7-34. You are trying to locate the best position for
commutation using the reverse rotation
1. A, C, D, B, and E method. Which of the following is the correct
2. C, B, A, D, and E procedure for you to follow?
3. A, C, D, E, and B
4. C, A, D, B, and E 1. Center one coil of the armature over the
adjacent pole pieces
7-30. On propulsion and magnetic minesweeping 2. Use full load, measure the speed, reverse
equipment, only one grade of brush is the direction of rotation, and adjust the
permitted. What means is used to determine reversing the rotation and adjusting the
the grade? brushes until the rated speed is achieved
3. Use a full load, adjust the field strength
1. The manufacturer and terminal voltage, reverse the direction
2. The operating temperature of rotation, and adjust the field strength
3. The operating speed and terminal voltage again. Keep
4. The connected load reversing the rotation and adjusting the
field strength until the rated speed and
7-31. If you do not have the applicable technical voltage are attained
manual, what tension should be placed on the 4. Each of the above
brushes of integral kilowatt generators?
7-35. After 2 weeks of operation, a commutator
1. 1 1/2 psi develops a bluish-colored surface. What is the
2. 2 to 2 1/2 psi cause?
3. 3 1/2 to 4 psi
4. 4 1/2 psi 1. Impurities in the brush material
2. Oxidation of the commutator bars
7-32. Brush holders should be no more than what 3. Normal commutation
(a) maximum distance nor what (b) minimum 4. Improper commutation
distance from the commutator of a motor or
generator? 7-36. What is the maximum distance an armature
commutator may be out of round?
1. (a) 1/8 inch (b) 1/8 inch
2. (a) 1/16 inch (b) 1/8 inch 1. 0.002 inch
3. (a) 1/16 inch (b) 1/16 inch 2. 0.005 inch
4. (a) 1/8 inch (b) 1/16 inch 3. 0.010 inch
4. 0.015 inch
52
7-37. Which of the following methods should you 7-42. When a large rotor is lifted by rope slings,
use to correct an out-of-round commutator? which of the following components should be
protected from the slings?
1. Grinding
2. Hand sanding 1. The ac rotor
3. Lathe turning 2. The dc armature
4. Machine stoning 3. The bearing journals
4. Each of the above
7-38. To true a commutator in place, you should use
which of the following methods? 7-43. In a wound-ac rotor, reduced torque, excessive
vibration, sparking at the brushes, and an
1. Sandpapering uneven collector ring are indications of what
2. Turning on a lathe electrical malfunction?
3. Grinding on a lathe
4. Hand- or machine-stoning 1. An opened rotor coil
2. An opened field coil
IN ANSWERING QUESTION 7-39, REFER TO 3. A shorted rotor coil
FIGURE 7-20 IN YOUR TEXTBOOK. 4. A shorted field coil

7-39. The good undercutting shown is best described

by which of the following statements? Learning Objective: Identify test, maintenance, and
rewind procedures for motors and generators.
1. The mica is cut low and square between
the copper segments
2. The mica is cut low and square between A. TEST FOR CONTINUITY
the commutator risers WITH AN OHMMETER
3. The mica and copper segments are cut B. TEST FOR MECHANICAL
high and square DIFFICULTIES
4. The mica is cut at a taper between C. TEST FOR GROUNDS
segments
D. VISUALLY INSPECT THE
STATOR
7-40. A commutator is being hand stoned. At what
recommended speed should the armature be
rotated? Figure 7C.

1. At or slightly over the rated speed IN ANSWERING QUESTION 7-44, REFER TO THE
2. At or slightly under the rated speed TESTING PROCEDURES SHOWN IN FIGURE 7C.
3. 50% of the rated speed
4. 25% of the rated speed 7-44. Of the sequences shown below, select the one
for testing a damaged stator.
7-41. You need to season commutators in minimum
time. To do this, you should start with 25% of 1. C, A, B, and D
full load operating for (a) what specified 2. C, D, B, and A
number of hours and then increasing the load 3. B, A, C, and D
to operate at (b) what percentage per hour until 4. C, B, A, and D
full load is reached?

1. (a) 4 (b) 15%/3

2. (a) 4 (b) 10%/1
3. (a) 3 (b) 15%/1
4. (a) 3 (b) 10%/3

53
7-45. When testing a three-phase, wye-connected 7-49. You are using an ohmmeter to test a three-
winding for shorted pole-phase groups, what phase, wye-connected winding for an open
method should you use? circuit. You get a low reading when the
ohmmeter leads are on terminals A and B, a
1. Connect the external leads of all phases to high reading when the leads are on B and C,
one test lead and another high reading when the leads are on
2. Apply low-voltage dc between each A and C. These readings indicate that there is
phase lead and the midpoint of the an open in what phase?
connected phases
3. Open each connected phase and apply 1. A
low-voltage dc to an open winding 2. B
4. Open each connected phase and apply 3. C
low-voltage ac to an open winding
7-50. When testing a three-phase, ac, delta-
7-46. What is the indication for a shorted pole-phase connected winding, you open each of the
group? connected phases and pass low-voltage dc
through all phases in series.
1. A north-seeking compass needle
2. A south-seeking compass needle 1. True
3. No deflection of the compass needle 2. False
4. A clockwise rotation of the compass
needle 7-51. Blue sparks that pass around the armature of a
running machine indicate an open armature
7-47. The balanced current test is performed on coil. The sparking occurs because, as the
three-phase ac windings to locate what type of segment to which the open coil is attached
motor malfunction? passes under a brush, the brush is performing
which of the following actions?
1. Open coils
2. Shorted phases 1. Closing and opening a circuit
3. Grounded coils 2. Burning the coil insulation
4. Reversed phases 3. Shorting out the coil
4. Grounding the coil
7-48. You are testing a three-phase, delta-connected
winding for a shorted phase. What procedure 7-52. After you have rewound and baked an
should you follow? armature rated at 500 volts, what is the lowest
megohm reading allowed? (NOTE: This
1. Open one delta connection and send low- reading is taken before a high-potential test.)
voltage ac through all phases connected
in series 1. 1.0 megohm
2. Open one delta connection and send low- 2. 2.0 megohms
voltage dc through the other two phases 3. 200.0 megohms
connected in series 4. 400.0 megohms
3. Open one delta connection and send low-
voltage ac through the other phases 7-53. A pole pitch is best described by which of the
connected in parallel following phrases?
4. Open each delta connection and send
low-voltage ac through each phase 1. The span of a coil
separately 2. The width of a coil
3. The distance between the centers of two
adjacent poles
4. The distance between the coil
connections

54
7-54. What is meant by the term progressive lap 7-57. The milliammeter decreases and then increases
winding? two times when the probe at segment 2 is
moved successively to each segment around
1. The winding is connected to segments the commutator. What type of winding is
two pole pitches apart, and the indicated?
connections progress in a
counterclockwise direction 1. Four-pole wave
2. The winding is connected to adjacent 2. Four-pole lap
segments, and the connections progress in 3. Six-pole wave
a counterclockwise direction 4. Six-pole lap
3. The winding is connected to segments
two pole pitches apart, and the 7-58. You are testing a commutator using the bar-to-
connections progress in a clockwise bar method. What equipment should you use?
direction
4. The winding is connected to adjacent 1. A voltmeter
segments, and the connections progress in 2. A frequency meter
a clockwise direction 3. A 6-volt battery and milliammeter
4. A Megger
7-55. What is the purpose of the bar-to-bar test in an
armature stripping procedure? IN ANSWERING QUESTION 7-59, REFER TO
FIGURE 7-44 IN YOUR TEXTBOOK.
1. To determine the type of winding
2. To identify the commutator pitch 7-59. The tool identified as number 5 is used for
3. To determine the coil throw which of the following functions?
4. To identify the coil pitch
1. To shape coil ends
2. To lift coil leads
3. To remove fiber wedges
4. To undercut the commutator

7-60. What means are used to classify electrical

insulating materials?

1. Their thickness
2. The materials they are made from
3. Their size
4. Their temperature indexes
7-61. What is the upper temperature rating of class A
insulation that has been immersed in
Figure 7D. dielectric?

IN ANSWERING QUESTIONS 7-56 AND 7-57, 1. 105°C

REFER TO THE ARMATURE WINDING 2. 130°C
IDENTIFICATION SHOWN IN FIGURE 7D. 3. 155°F
4. 80°F
7-56. The milliammeter reading decreases when the
probe at segment 2 is moved successively from 7-62. To prevent the pocketing of varnish when
segments 2 through 11 and then increases from 11 varnishing a stator, you should rotate the
through 21. What type of winding is indicated? armature during which of the following steps?

1. Simplex wave 1. Wiping

2. Duplex wave 2. Baking
3. Simplex lap 3. Dipping
4. Duplex lap 4. Draining
55
7-63. What method should you use to conduct an ac
high-potential test on a newly rewound
armature?

1. Apply the test voltage across the

grounded shaft and each of the
commutator segments individually
2. Short-circuit the commutator segments
with several turns of bare wire and apply
the test voltage across the common
connection and the grounded armature
shaft
3. Disconnect the leads of each of the coils
and apply the test voltage across each coil
individually
4. Apply the test voltage across the Figure 7E.
grounded shaft and the bearings of the
shaft IN ANSWERING QUESTION 7-67, REFER TO THE
THREE-PHASE, FOUR-POLE, SERIES WYE
7-64. Before assembling the coils in an armature, WINDING SHOWN IN FIGURE 7E.
what type of insulation should you place in the
coil slots? 7-67. In what direction does current flow in group 10
of phase A?
1. Class A
2. Glass tape 1. In the opposite direction of group 3
3. Polyamide paper 2. In the opposite direction of group 4
4. Rigid, laminated-type 3. In the same direction as group 1
GME-MIL-P-15037 4. In the same direction as groups 1, 4, and 7

7-65. To prevent centrifugal force from throwing the 7-68. When you have completed winding a coil,
coils outward, when should you place the which of the following devices should you use
banding wire on the armature? to make a polarity check?

1. Before baking 1. A compass

2. After baking 2. An ammeter
3. Before prebaking 3. A voltmeter
4. While the coils are hot 4. A megohmmeter

7-66. What, if anything, is the difference between 7-69. DC motors are usually reversed by a change in
shunt and series field coils? the direction of current flow through the
armature for which of the following reasons?
1. Shunt coils are made of a few turns of
heavy wire, and series field coils are 1. The series field is hard to reach
made of many turns of fine wire 2. The armature leads are longer
2. Shunt field coils are made of many turns 3. Only one element is involved
of fine wire, and series field coils are 4. All of the above
made of fewer turns of heavy wire
3. Shunt field coils are wound clockwise, 7-70. What means should you use to reverse the
and series field coils are wound counter- direction of rotation of a three-phase motor?
clockwise
4. Nothing; both are identical 1. Shift the neutral plane
2. Reverse the shunt field leads
3. Reverse two motor leads only
4. Reverse all three motor leads
56
7-71. Usually, what is the cause of single-phase 7-73. The running and starting windings are placed
motor failure? in the stator of a single-phase motor in which
of the following ways?
1. A loss of line voltage
2. Bearing failure 1. The starting winding is placed in the
3. Running winding failure bottom of the slots, and the running
4. Starting winding failure winding is placed on top of the running
winding
IN ANSWERING QUESTION 7-72, REFER TO 2. The running winding is placed in the
FIGURE 7-70 IN YOUR TEXTBOOK. bottom of the slots, and the starting
winding is placed on top of the running
7-72. If the motor is running on 110 volts, and you winding
want to run it on 220 volts, you should connect 3. The running and starting windings are
the windings in what way? placed in series with one another
4. The running and starting windings are
1. Connect the run windings in series placed in opposite slots within the stator
2. Connect the start windings in parallel
3. Connect both the run and start windings
in parallel with each other
4. Connect the start and run windings in
series with each other

57
 ASSIGNMENT 8
Textbook Assignment: “Voltage and Frequency Regulation,” chapter 8, pages 8-1 through 8-44.

Learning Objective: Recognize the Learning Objective: Recognize the operating

characteristics of type I, II, and III ac power principles of direct-acting voltage regulators and
systems. identify the operating procedures of ship’s
service installations using direct-acting voltage
regulators.
8-1. Refer to table 8-1 in your textbook. What type
of electrical power has the most stringent
voltage and frequency requirements? 8-6. Spare voltage-sensitive control elements are
NOT installed for voltage regulators on which
1. Type I of the following equipment?
2. Type II
3. Type III 1. Motor generator sets
4. Type IV 2. Ship’s service switchboards
3. Emergency switchboards
8-2. Type III power is normally produced by what 4. Static frequency changers
means?
8-7. In the direct-acting rheostatic voltage
1. Ship’s service turbine generators regulator, what part exerts a mechanical force
2. Diesel emergency generators directly on a special type of regulating
3. Steam-driven dc generators resistance?
4. Motor generator sets
1. Interlocking springs
8-3. The automatic voltage regulator maintains the 2. Electric solenoid
generator’s output voltage by regulating the dc 3. Regulator coil
through what part of the static exciter? 4. Leaf springs

1. The control winding 8-8. In what configuration, if any, is the voltage

2. The primary winding regulator connected to the shunt field of the
3. The linear conductor exciter?
4. The secondary winding
1. In series
8-4. What factor determines the magnitude of the 2. In parallel
generated voltage of an ac generator? 3. In series-parallel
4. None
1. Resistance of the field windings
2. Strength of the field flux 8-9. The silver buttons in a Silverstat voltage
3. Size of the armature windings regulator are connected to taps on what
4. Type of prime mover used component(s)?

8-5. Which of the following methods is normally used 1. Regulator coil

to provide voltage control in a dc generator? 2. Voltage-adjusting rheostat
3. Regulating resistance plates
1. A rheostat is placed in series with the load 4. Range-setting resistors
2. The speed of the generator is varied
3. The strength of the generator shunt field
is varied
4. All of the above

58
8-10. The range covered by each voltage-adjusting 8-13. You are switching a direct-acting voltage
rheostat of the regulator can be set so the regulator system from manual to automatic
rheostat’s midposition is in the normal operating control. It is necessary for you to leave the
position to obtain the rated generator voltage. control switch in the TEST position
What component should you adjust to set the momentarily to allow which of the following
range? actions to occur?

1. The damping transformer 1. The exciter field current to stabilize

2. Resistors connected in series with the 2. The generator field current to stabilize
regulator coil 3. The damping transformer transient
3. The resistance plate connected in series current to die down
with the rheostat 4. The silver buttons to readjust
4. The resistance plate connected in parallel
with the rheostat 8-14. The moving arm of a direct-acting regulator
will behave in what way if the damping
8-11. In what configuration is the primary of the transformer connections are reversed?
damping transformer connected in a regulator
that controls a large ac generator? 1. It will swing continuously from one end
of its travel to the other
1. Across the output of the exciter 2. It will move very sluggishly in response
2. In series with the voltage-adjusting to a generator voltage change
rheostat 3. It will be pulled toward the regulator coil
3. In series with the regulator coil and remain in that position
4. Across the output of the cross-current 4. It will be pulled away from the regulator
compensator coil and remain in that position

8-12. In what way does a direct-acting voltage

regulator respond to a decrease in generator Learning Objective: Recognize the operating
load? principles of the rotary amplifier (amplidyne) type
of voltage regulator and identify the procedures
1. The regulator armature is pulled toward used to operate ship’s service installations with
the regulator coil, more silver buttons are this type of regulator.
pushed together, and the regulating
resistance increases
8-15. The voltage regulator transfer switch for two
2. The regulator armature is pulled toward
generators (A and B) is in the GEN B position.
the regulator coil, more silver buttons are
The voltages of the generators are controlled
spread apart, and the regulating resistance
in what way?
increases
3. The regulator armature is pulled away
1. Both generator A and B are controlled by
from the regulator coil, more silver
generator B’s regulator
buttons are pushed together, and the
2. Only generator B is regulated, since
regulating resistance decreases
generator A is out of the circuit
4. The regulator armature is pulled away
3. Generator A is controlled by the standby
from the regulator coil, more silver
regulator, and generator BA is controlled
buttons are spread apart, and the
by its own regulator
regulating resistance decreases
4. Generator A is controlled by its own
regulator, and generator B is controlled
by the standby generator

59
8-16. The stabilizer functions to prevent hunting in 8-20. By what means does the automatic control
the voltage regulator circuit. It does this by circuit oppose an increase in ac generator
what means? voltage?

1. It aids any change in the amplidyne 1. The saturated reactor current increases,
control field current causing an increase in the amplidyne
2. It decreases the inductance of the control field current
saturated reactor 2. The pilot alternator voltage decreases,
3. It increases the inductance of the causing a decrease in the amplidyne
saturated reactor control field current
4. It opposes any change in amplidyne 3. The pilot alternator voltage increases,
control field current causing an increase in the amplidyne
control field current
8-17. When the number of saturated reactor coil 4. The saturated reactor current decreases,
turns in the voltage adjusting unit is decreased, causing a decrease in the amplidyne
the inductance of the saturated reactor reacts in control field current
what way?
8-21. A decrease in generator frequency affects the
1. It decreases, and the voltage held by the reactance of the saturated reactor and the
regulator is lowered frequency compensation circuit in what way?
2. It increases, and the voltage held by the
regulator is lowered 1. The reactance of the saturated reactor
3. It decreases, and the voltage held by the increases, and the frequency
regulator is raised compensation network behaves like an
4. It increases, and the voltage held by the inductance
regulator is raised 2. The reactance of the saturated reactor
increases, and the frequency
8-18. What unit provides the regulator with a signal compensation network behaves like a
proportional to the ac generator voltage? capacitance
3. The reactance of the saturated reactor
1. The pilot alternator decreases, and the frequency
2. The amplidyne unit compensation network behaves like an
3. The potential unit inductance
4. The stabilizer 4. The reactance of the saturated reactor
decreases, and the frequency
IN ANSWERING QUESTION 8-19, REFER TO compensation network behaves like a
FIGURE 8-8 IN YOUR TEXTBOOK. capacitance

8-19. If the generator voltage is near normal in the 8-22. At unity power factor, the compensating
automatic control circuit, buck circuit current voltage across the compensating potentiometer
from F2 to F1 in the amplidyne control field rheostat is in phase with what voltage?
has what magnitude?
1. Voltage across the teaser leg of the
1. Nearly equal to the boost circuit current T-connected potential transformer
2. Maximum to overcome the boost circuit secondary
current 2. Resultant output voltage of the three-
3. Minimum to enable the boost circuit phase response network
current to keep the amplidyne control 3. Phase B line-to-neutral voltage
field steady 4. Voltage across the resistor-inductor series
4. Negligible circuit in the three-phase response
network

60
8-23. Two generators are placed in parallel operation 8-26. The output of the static exciter is controlled by
in a rotary voltage regulator system. By what the current through what circuit component(s)?
means are the load distribution and power
factor adjusted? 1. Transformer primaries
2. Transformer secondaries
1. The manual control handwheels and 3. Transformer control windings
prime mover governors 4. Output rectifier CR1
2. The manual control handwheels and the
voltage-adjusting unit 8-27. The automatic voltage regulator maintains the
3. The voltage-adjusting unit and prime generator’s output voltage by regulating the dc
mover governors through what part of the static exciter?
4. The voltage-adjusting unit and the
saturated reactor tap switch 1. The control winding
2. The primary winding
8-24. You should check the amplidynes’ short- 3. The linear inductor
circuiting brushes periodically for what 4. The secondary winding
reason?
IN ANSWERING QUESTIONS 8-28 THROUGH 8-31,
1. Improper brush contact may result in an REFER TO FIGURE 8-16 IN YOUR TEXTBOOK.
excessively high amplidyne voltage
output 8-28. The reactance value of L6 in the voltage
2. They tend to arc and spark more than regular depends on what other value?
other brushes
3. Heat developed tends to loosen electrical 1. The average of the line voltages
connections 2. The output of CR
4. Short-circuiting causes them to wear 3. The value of the secondary of T5
faster, shortening their life 4. The output of CW1

8-29. Each magnetic amplifier is operated in the

Learning Objective: Recognize the operating center portion of its magnetic core saturation
principles of the static excitation voltage regulator curve by adjusting what components?
system and identify the procedures for operating
the ship’s service installation using this system. 1. L7 and R13
2. R11 and R12
3. L6 and L1
IN ANSWERING QUESTIONS 8-25 THROUGH 8-27,
4. R14 and R15
REFER TO FIGURE 8-12 IN YOUR TEXTBOOK.
8-30. The initial field current for starting the ac
8-25. Switches S1 and S2 contain a large number of
generator is provided by which of the
series-connected contacts for what reason?
following components?
1. To eliminate arcing when turned to the
1. The static exciter
OFF position
2. The output rectifiers
2. To minimize arcing effects when power is
3. A 50 kW, dc generator
removed
4. Each of the above
3. To provide multiple circuit path
connections
4. To prevent the contacts from becoming
hot

61
8-31. The steady state and transient frequency 8-35. You should frequently inspect the SPR-400
requirements for type II power can be met with line voltage regulator for which of the
electro-hydraulic governors. However, a following possible causes of improper
motor generator or static converter will still be operation?
required for what type of voltage control?
1. Dust
1. I 2. Dirt
2. V 3. Moisture
3. III 4. All of the above
4. IV

Learning Objective: Identify the operating

Learning Objective: Recognize the operating fundamentals of the 30 kW motor-generator set.
principles of the SPR-400 voltage regulator and
identify maintenance requirements.
8-36. What means is used to control the output of the
8-32. The purpose of the SPR-400 line voltage static exciter?
regulator is to ensure precision control of
variations in which of the following factors? 1. A preamp and trigger circuit
2. The output of the power section of the
1. Line voltage regulator acts on windings within the
2. Load changes static exciter
3. Power factor 3. An ac error signal is produced by a three-
4. All of the above phase bridge rectifier
4. The signal produced by chokes in series
8-33. If there is a decrease of the dc in the control with the generator output
winding, what is the effect of the (a) voltage of
the opposing winding and (b) output of the 8-37. What means are used to control the SCRs in
autotransformer? the power circuit?

1. (a) Decreases (b) decreases 1. By using an amplified error signal that is

2. (a) Decreases (b) increases developed in the reference bridge and fed
3. (a) Increases (b) decreases through a unijunction transistor circuit
4. (a) Increases (b) increases 2. By varying the excitation to the Zener
diodes
8-34. Refer to figure 8-20 in your textbook. The 3. By varying the firing time of the main
purpose of potentiometer R21 is to compensate SCR in each inverter
for what factor? 4. By providing a signal proportional to the
converter input voltage
1. The resistance in the cables from the
regulator to the load 8-38. What means is used to provide the no-load
2. The internal resistance of the regulator field excitation to the motor-generator set?
3. The resistance of the regulator load
4. The resistance of the input voltage 1. Current flowing through the SCPT
primaries
2. The rectified output of the secondary
windings of the SCPT
3. The output of the voltage divider network
4. The field-flashing circuit

62
8-39. Variations in generator output frequency is 8-43. The synchronizing monitor is connected to a
compensated for the circuit consisting of two generators and the K1
relay is energized. In what way does this
1. drive motor current being increased or configuration affect the parallel operation of
decreased the generators?
2. drive motor voltage being increased or
decreased 1. They are automatically paralleled
3. resistance being placed in parallel with 2. They are not automatically paralleled but
the stator windings may be manually paralleled
4. excitation to the stator being increased or 3. They may not be paralleled while the K1
decreased relay is energized but are automatically
paralleled when it is de-energized
4. They may not be paralleled while the K1
Learning Objective: Identify the operating relay is energized but may be manually
characteristics of static converters. paralleled when the relay is de-energized

IN ANSWERING QUESTIONS 8-44 THROUGH 8-46,

8-40. By what means does the voltage act to regulate
REFER TO FIGURE 8-28 IN YOUR TEXTBOOK.
converter output voltage?
8-44. The reference bias voltage for Q1 in the
1. By varying the excitation to the Zener
synchronizing monitor appears across what
diodes
component?
2. By providing a constant voltage to the
main SCR in each inverter
1. Capacitor C1
3. By controlling the firing time of the main
2. Resistor R2
SCR in each inverter
3. Resistor R6
4. By controlling the main SCR with a
4. Zener diode CR8
signal proportional to the converter input
voltage
8-45. The phase difference circuit turns Q1 off as a
result of what action?
8-41. In mode 1 operation, what drives the ac end of
the motor generator?
1. Reverse bias voltage across CR10
2. Reverse bias voltage across R6
1. The ship’s service power supply
3. Base-to-emitter short caused by the
2. The standby batteries
conduction of CR9
3. The emergency diesel generator
4. Base-to-emitter short caused by the
4. The attached turbine
conduction of CR10

Learning Objective: Recognize the operating 8-46. The voltage difference circuit turns off as a
fundamentals of the synchronizing monitor. result of what action?

1. Reverse bias voltage across Q5

IN ANSWERING QUESTIONS 8-42 AND 8-43, 2. Reverse bias voltage across R19
REFER TO FIGURES 8-26 AND 8-27 OF YOUR 3. Base-to-emitter short caused by the
TEXTBOOK. conduction of CR18
4. Base-to-emitter short caused by the
8-42. The K1 relay is energized for which of the conduction of Q5
following examples of phase angle (θ), voltage
difference (∆V), and frequency difference (∆F)?

1. θ = -45°, ∆V = 1%, ∆F = 0.1 Hz

2. θ = -22°, ∆V = 3%, ∆F = 0.1 Hz
3. θ = 0°, ∆V = 5%, ∆F = 0.5 Hz
4. θ = + 5°, ∆V = 5%, ∆F = 2.0 Hz
63
8-47. Refer to figure 8-34 in your textbook. Which 8-49. Refer to figure 8-35 in your textbook. This
of the following components in the frequency figure shows the results of various steps in the
difference monitoring circuit are connected so generation of a signal that is used to fire SCR1
that a beat frequency voltage is produced in the frequency difference monitoring circuit.
between the oncoming generator and the bus? What is the purpose of the step that produces
the waveform shown in diagram E?
1. Primaries of T2 and T3
2. Secondaries of T2 and T3 1. To produce a beat frequency voltage be-
3. Secondaries of T2 and CR11 tween the oncoming generator and the bus
4. Transistors Q3 and Q4 2. To rectify and filter the beat frequency
voltage
3. To assure that the clipped signal goes to
zero when the original beat frequency
voltage goes to zero
4. To assure that the clipped beat frequency
signal maintains a constant dc level

8-50. A unijunction transistor has 0 volts on base 1

and 12 volts on base 2. If the transistor fires
when the base 1-to-emitter voltage reaches 8
volts, the transistor has what eta value
(intrinsic standoff ratio)?

1. 1 to 3
2. 1 to 2
3. 2 to 3
4. 4 to 3

IN ANSWERING QUESTIONS 8-51 THROUGH 8-53,

REFER TO FIGURES 8-34, 8-36, AND 8-37 IN YOUR
TEXTBOOK.
Figure 8A.
• Study Hint: Assume that the difference in
IN ANSWERING QUESTION 8-48, REFER TO frequency between the oncoming generator voltage
FIGURE 8A. and the bus voltage is 0.2 Hz.

8-48. When occurring simultaneously with the 8-51. What is/are the time constant period(s) for one
indicated bus voltage, what generator voltage cycle of the beat frequency voltage?
will produce the maximum current flow in
CR10 in the phase difference monitoring 1. 0.5
circuit of the synchronizing monitor? 2. 2.0
3. 2.5
1. A 4. 5.0
2. B
3. C
4. D

64
8-52. What is the function of the frequency 8-56. What is the purpose of R19?
differential circuit?
1. To prevent large voltage variations
1. To energize relay K1 through the control 2. To de-energize relay K1
of transistor Q2 3. To ensure that Q5 will remain off when
2. To match the impedance of the static relay K1 is de-energized
exciter of the generators being paralleled 4. To ensure that Q5 will remain off when
3. To prevent excessive frequency variations K1 is energized
in the generators being monitored
4. To take the monitored generator off line
if the frequency output varies by more Learning Objective: Identify the techniques used
than 4 Hz to service transistorized circuits.

8-53. By which of the following means is Q2

8-57. High-power transistors that are noticeably hot
controlled?
while operating have been damaged beyond
use.
1. Simultaneous action of the voltage
difference circuit and the frequency
1. True
difference circuit
2. False
2. The frequency difference circuit only
3. The phase difference circuit only
8-58. When using a signal generator as a transistor
4. Either 1 or 2 above, depending on the
tester, what is the first connection you should
voltage difference circuit or the phase
make?
difference circuit
1. Connect the power line to an isolation
IN ANSWERING QUESTIONS 8-54 THROUGH 8-56,
transformer
REFER TO FIGURE 8-40 IN YOUR TEXTBOOK.
2. Connect the chassis of the signal
generator to ground
8-54. In the voltage difference monitoring circuit,
3. Connect the chassis of the signal
the K1 relay will not close if the voltage
generator to the chassis of the equipment
difference in the generators is more than what
to be tested
specified percentage?
4. Connect the line voltage to the signal
generator
1. 5%
2. 2%
8-59. What action should you take to prevent
3. 3%
damage to a transistor?
4. 4%
1. Always ground the base of the transistor
8-55. The difference in the magnitude of the sensing
before conducting any resistance tests
signals from the oncoming generator and the
2. Use isolation transformers to protect
bus is detected in what bridge circuit
transistors from test equipment
component?
3. When using an ohmmeter, use only those
ranges that pass 2 mA or less
1. CR15
4. Use only signal tracers with a
2. CR16
transformerless power supply
3. CR17 (points A and B)
4. CR18 (points A and B)

65
8-60. Multimeters that are used for voltage 8-61. Ohmmeters will damage transistors if the
measurements in transistor circuits should have meters have a range that is greater than what
what minimum high ohms/volt sensitivity? maximum amperage?

1. 5,000 ohms/volt 1. 1.00 mA

2. 10,000 ohms/volt 2. 0.25 mA
3. 15,000 ohms/volt 3. 0.50 mA
4. 20,000 ohms/volt 4. 0.75 mA

66
 ASSIGNMENT 9
Textbook Assignment: “Electrohydraulic Load-Sensing Governors” and “Degaussing,” chapters 9 and 10, pages 9-1
through 10-21.

9-4. What does the speed droop do for the

Learning Objective: Recognize various operation of a generator?
governor controls and operations.
1. It allows you to parallel generators that
have dissimilar governors
9-1. What is the advantage of using
2. It prevents overspeeding of the prime
electrohydraulic governors instead of
mover
mechanical governors?
3. It slows down the generator when an
overload condition exists
1. Electrohydraulic governors are more
4. It prevents you from paralleling
powerful for a given size
generators unless the frequency of both
2. Mechanical governors are more
generators is the same
expensive to maintain
3. Electrohydraulic governors provide closer
9-5. Which of the following means should be used
frequency regulation
to give the governor a signal that corresponds
4. Mechanical governors are more prone to
to the speed of the equipment under control?
misadjustment because of shock
1. The dc signal developed in the reference
9-2. Which of the following is a disadvantage of
circuit
obtaining the speed signal of a governor by
2. The output voltage of the generator being
sensing the output frequency of the generator?
controlled
3. A permanent magnet generator or
1. A short circuit on the generator could
alternator mounted on the shaft of the
result in a loss of signal
equipment
2. The governor responds slower to speed
4. Both 2 and 3 above
changes
3. Frequent load changes will cause the
9-6. What means is used to connect the load-
governor to hunt
measuring circuits of governors on all
4. The governor must be manually
generators operating in parallel?
controlled when paralleling with another
generator
1. A bus tie cable
2. An isolation transformer
9-3. What means is used to obtain stability in the
3. Common ground connections
prime mover?
4. Feedback circuits
1. Electrical feedback circuits
9-7. What is the purpose of the load signal box in
2. Speed signals are filtered to remove
EG-R governors?
ripples
3. Backup circuits automatically replace
1. To allow the governor to be paralleled
signals lost by open switches
with dissimilar generators
4. Sensitivity adjustments on the governor
2. To prevent the governor from hunting by
provide precise speed control
producing negative feedback signals
3. To detect changes in the load before they
appear as speed changes
4. To provide the backup signal to the
governor if the speed signal is lost

67
9-8. What device is used to couple the EG-R
hydraulic actuator to the remote servo piston? A. Acts to produce the temporary negative feedback
(in the form of a pressure differential) applied to
1. Electrical cables the compensation land of the pilot valve plunger
2. High-pressure lines during speed changes
3. A mechanical linkage
B. Reacts to the position of the control land to
4. A buffer piston increase or decrease the speed of the prime
mover through a linkage to the fuel or steam
9-9. What type of governor system offers the
valve
highest work capacity?
C. Prevents overtravel of the throttle by reacting to
1. EG-R a temporary negative feedback signal in the
2. EG-4 with a hydraulic actuator form of a pressure differential across it during
3. EG-3C changes in position of the power piston
4. EGB-2P
D. Used to control the rate at which the pilot valve
9-10. If a negative dc voltage is sent to the actuator plunger returns to the centered position after a
from the electronic control box, what will change in load condition on the prime mover
happen to the pilot valve plunger?
Figure 9A.
1. It will travel in an upward direction
2. It will travel in a downward motion
IN ANSWERING QUESTIONS 9-13 THROUGH
3. It will maintain its steady state position
9-16, REFER TO FIGURE 9A AND SELECT THE
4. It will hunt in an upward and downward
DESCRIPTION OF THE COMPONENT OF THE
motion
ELECTROHYDRAULIC GOVERNOR USED AS
THE QUESTION.
9-11. If the power piston is forced down, the fuel
flow to the prime mover will react in what
9-13. Compensation land.
way?
1. A
1. It will decrease
2. B
2. It will increase
3. C
3. It will stop
4. D
4. It will remain the same
9-14. Buffer system.
9-12. Control oil pressure is approximately (a) what
amount of (b) what oil pressure?
1. A
2. B
1. (a) 1/4 (b) compensation
3. C
2. (a) 1/2 (b) residual
4. D
3. (a) 1/4 (b) residual
4. (a) 1/2 (b) compensation
9-15. Needle valve.

1. A
2. B
3. C
4. D

68
9-16. Power piston. 9-21. Which of the following is an application of a
hydraulic amplifier?
1. A
2. B 1. Operating a power control mechanism
3. C when little force is required
4. D 2. Operating a power control mechanism
when a relatively large force is required
9-17. By what means does the EG-R actuator control 3. Diesel engines
the position of the prime mover fuel or steam 4. On the output of generators, developing a
supply? signal proportional to the frequency

1. By using the centrifugal force of a 9-22. When used, the three-way valve of the EG-R
ballhead device to cause the pilot valve to hydraulic actuator must be turned to drain
move up or down after starting for what reason?
2. By controlling the flow of oil to and from
the upper side of the power piston in the 1. Oil caught in the line would cause false
remote servo signals in the amplifier
3. By developing a signal proportional to the 2. Oil would be trapped under the pilot
output speed and applying it to the valve plunger, making the amplifier
ballhead governor section inoperative
4. By controlling the excitation to the 3. Sediment from the oil would collect and
external three-phase potential cause the governor to fail
transformers 4. Oil pressure would rise and cause the
relief valve to lift
9-18. With the pilot valve of the EG-R actuator
centered, in what direction, if any, is oil 9-23. Which of the following is NOT a use of the
directed by the power piston? EG-M control box?

1. To the right side of the buffer piston 1. To convert the input from the pMG into a
2. To the bottom of the power piston negative speed signal
3. To the top of the power piston 2. To provide the control signal to the
4. None; no oil flows electronic amplifier in ;the load signal
control box
9-19. An increase in prime mover speed will cause 3. To convert a three-phase input signal
the EG-R control box to send a signal to from the generator into a +dc signal
complete what action? 4. To develop an error voltage using the
outputs of the speed section and the speed
1. Slow the oil pump gears reference section
2. Lower the power piston
3. Raise the pilot valve plunger 9-24. It is desirable to detect load changes and
4. Lower the pilot valve plunger respond to them before they appear as turbine
speed changes for what reason?
9-20. The pilot valve plunger of the EG-R actuator is
moved by the pressure on top of the 1. To increase efficiency
compensation land. What component controls 2. To decrease line losses
the rate at which the plunger moves? 3. To minimize speed change transients
4. To minimize line voltage transients
1. The needle valve setting
2. The strength of the buffer piston spring
3. The relief valve spring pressure stations
4. The strength of the signal acting on the
armature magnet

69
9-25. What is the primary source of most problems 9-29. The earth’s magnetic field is made up of what
in the hydraulic actuator or valve operator? components?

1. Dirty oil 1. The H and Z zones

2. Incorrect needle valve setting 2. The H and X zones
3. Incorrect speed reference setting 3. The Z and Y zones
4. Wrong type of oil used 4. The X and Y zones

9-30. What instrument is used to determine the angle

Learning Objective: Recognize the principles of the horizontal field?
of the earth’s magnetic fields as they relate to
the degaussing systems. 1. A pivotal voltmeter
2. A strength ammeter
3. A navigational compass
9-26. A ship’s magnetic field moves with the ship
4. A dip needle
through the water. Because of this magnetic
field, the ship can trigger magnetic-sensitive
9-31. At the equator, what is the vertical intensity of
ordnance. Degaussing systems are used
the earth’s magnetic field?
aboard ship for which of the following
reasons?
1. Maximum, upward, and positive
2. Minimum, downward, and negative
1. To trigger sensitive devices
3. Perpendicular and zero
2. To protect the hull from rust
4. Horizontal and zero
3. To help reduce the ship’s distortion of the
earth’s magnetic field
9-32. The magnitude of a ship’s permanent
4. To make the ship’s hull a large magnet
magnetism depends on which of the following
conditions?
9-27. The lines of magnetic force at the earth’s
surface don’t run in straight lines. They appear
1. The earth’s magnetic field where the ship
more like isobar lines on a weather map. The
was built
lines of force interact with ferrous materials in
2. The material from which the ship is
what way?
constructed
3. The orientation of the ship at the time the
1. They align the lines of force around
ship was built with respect to the earth’s
longitude
magnetic field
2. They distort the background field into
4. All of the above
areas of increased or decreased magnetic
strength
9-33. Navy ships are depermed for which of the
3. They create an induced magnetic field
following reasons?
4. They distort to avoid passing near the
ferrous material
1. To increase the number of the ship’s
effective degaussing coils
9-28. On earth, where is the south magnetic pole
2. To decrease the permanent magnetization
located?
of the ship
3. To decrease the induced magnetization of
1. In the southern hemisphere
the ship
2. In the northern hemisphere
4. All of the above
3. At the equator
4. Half way between the north and south
geographic poles

70
 9-37. A ship’s induced magnetism depends on which
of the following components?

1. The strength of the earth’s magnetic field

2. The heading of the ship with respect to
the inducing earth’s magnetic field
3. Both 1 and 2 above
4. The vertical induced component of magnetism

9-38. What two field components make up the

horizontal field of a ship’s induced magnetism?

1. The longitudinal and athwartship

2. The vertical induced and athwartship
3. The longitudinal and the vertical
4. The athwartship and the vertical
Figure 9B.
9-39. The magnitude of the vertical field component of
IN ANSWERING QUESTIONS 9-34 AND 9-35, a ship’s induced magnetization depends on what
REFER TO THE EARTH’S MAGNETIC FIELD factor?
SHOWN IN FIGURE 9B.
1. The ship’s heading
9-34. The earth’s magnetic field lines of force enter 2. The magnetic latitude
the surface at what location? 3. The magnetic longitude
4. The horizontal induced field component
1. The north magnetic pole
2. The south magnetic pole
3. The magnetic equator
4. A point midway between the magnetic
equator and the South Pole

9-35. At what location on the earth’s surface do the

magnetic lines of force point away with the
strongest flux?

1. A
2. B
3. C Figure 9C.
4. D
IN ANSWERING QUESTIONS 9-40 AND 9-41, REFER
TO THE THREE COMPONENTS OF THE SHIP’S
9-36. The horizontal component of the earth’s
INDUCED MAGNETISM SHOWN IN FIGURE 9C.
magnetic field is maximum at which of the
following locations? 9-40. When the ship is on a southerly heading at the
magnetic equator, the induced magnetisms of
1. The magnetic equator AB, CD, and EF have what relationship?
2. The north pole of the magnetic core
3. The south pole of the magnetic core 1. AB and CD are maximum, and EF is
4. Both 2 and 3 above minimum
2. AB is maximum, and CD and EF are
minimum
3. CD is maximum, and AB and EF are
minimum
4. EF and CD are maximum, and AB is
minimum
71
9-41. A ship steaming on a north heading changes 9-47. The magnetic fields produced by the
course to the east. What effect does this have permanent and induced vertical components of
on the ship’s induced magnetic field? a ship’s magnetization are counteracted by
which of the following degaussing coils?
1. CD changes from zero to maximum
2. CD changes from maximum to zero 1. A
3. EF changes from maximum to minimum 2. L
4. AB changes from maximum to minimum 3. M
4. F
9-42. The equipment that measures the magnetic
field of a ship at a degaussing range has which 9-48. The ship’s vertical induced magnetization
of the following physical locations? varies with which of the following factors?

1. At or near the bottom of the channel 1. The ship’s latitude

2. On the ship 2. The ship’s pitch
3. Ashore 3. The ship’s roll
4. Both 2 and 3 above 4. All of the above

9-43. A ship is check ranged for which of the 9-49. The forward one-fourth to one-third of a ship
following reasons? is encircled by which of the following coils?

1. To ensure that the degaussing coil 1. Q

settings match those given in the 2. M
degaussing folder 3. L
2. To determine if the ship requires the 4. F
installation of additional degaussing coils
3. To ensure that the current settings are 9-50. The strength of the FI-QI and FP-QP coils
adequate depends on which of the following factors?
4. To ensure that the degaussing charts are
accurate 1. The ship’s heading and draft
2. The ship’s draft and latitude
9-44. At what specified interval must minesweepers 3. The ship’s latitude and heading
be checked at a degaussing range? 4. The ship’s heading and speed

1. Semiannually 9-51. The FI-QI degaussing coils counteract which

2. Quarterly of the following fields?
3. Monthly
4. Weekly 1. Longitudinal permanent
2. Longitudinal induced
9-45. What is the minimum number of coils in a 3. Athwartship induced
degaussing system? 4. Vertical induced

1. One 9-52. The L coil is installed aboard what type of

2. Two ship?
3. Three
4. Four 1. An aircraft carrier
2. A replenishment ship
9-46. Degaussing coils are energized from what type 3. A submarine
of power sources? 4. A minesweeper

1. The 120-volt lighting circuit

2. The 48-volt gyro batteries
3. Direct current
4. Alternating current
72
 Figure 9D.

IN ANSWERING QUESTION 9-53, REFER TO 9-57. What equipment is used to automatically

FIGURE 9C AND THE DEGAUSSING COIL control the current of degaussing systems?
LOCATIONS SHOWN IN FIGURE 9D.
1. A gyrocompass and magnetometer
9-53. The magnetism of the fore-aft component is 2. A magnetometer and reversing switch
counteracted by which of the following coils? 3. A magnetometer and gyrocompass
control
1. 3 and 4 only 4. A polarity switch and gyrocompass
2. 4 and 5 only
3. 1, 3, and 5 9-58. A magnetometer that controls the induced field
4. 2, 4, and 5 currents receives a signal from what total
number of axes?
9-54. A degaussing coil for correcting athwartships
permanent and athwartships induced 1. One
magnetization has what designation? 2. Two
3. Three
1. A 4. Four
2. AX
3. API 9-59. The AUTODEG equipment must be secured if
4. AP-AI the automatic controls become inoperative.

9-55. Magnetic fields produced by the permanent 1. True

and induced longitudinal components of a 2. False
ships magnetization are counteracted by which
of the following coils? 9-60. Magnetometer-controlled AUTODEG
equipment has what total number of modes of
1. F operation?
2. L
3. Q 1. One
4. Each of the above 2. Two
3. Three
9-56. Which of the following conditions can change 4. Four
a ship’s attitude?
9-61. The degaussing system coil turns, current
1. Roll magnitude, and polarities for a ship are
2. Trim established during calibration. Calibration is
3. Heading accomplished at what location?
4. Each of the above
1. A degaussing range
2. A deperming crib
3. A dry dock
4. A pier

73
9-62. Degaussing coil currents should be monitored 9-68. What is the required length for all conductors
and compared to which of the following inside a connection box?
values?
1. 1 1/2 times the length to the farthest
1. Those previously recorded on the terminal
degaussing log 2. 1 1/2 times the length to the nearest
2. Those recorded in the degaussing folder terminal
3. Those listed in the quartermaster’s log 3. 2 times the length to the nearest terminal
4. Those listed in the degaussing technical 4. 2 times the length to the farthest terminal
manual
9-69. The degaussing folder is an official ship’s log.
9-63. When the EMS degaussing system is in the
manual mode, the M-coil switch is set to what 1. True
polarity? 2. False

1. Positive for northern latitudes 9-70. The degaussing folder is prepared by what
2. Positive for southern latitudes person?
3. Negative for northern latitudes
4. Neutral for all latitudes 1. The navigator
2. The engineer
9-64. When the ship’s heading changes and the 3. The electrical officer
geographical location does not, the magnitude 4. The degaussing range personnel
and polarity of what components will vary?
9-71. At what point is the degaussing folder
1. FP-QP and L prepared?
2. FI-QI and A
3. FP-QP and M 1. After each yard period
4. L, A, and FI-QI 2. Once each year
9-65. In the SSM degaussing system, which of the 3. Once each 5 years
following components is/are installed to warn 4. During initial calibration
personnel of faulty operations?
9-72. You should NOT use which of the following
1. Ground detectors equipment to remove dust and dirt from
2. Temperature alarm automatic degaussing control equipment?
3. Blown fuse indicators
4. Each of the above 1. LP air
2. A bellows
9-66. What method is used to mark the insulating 3. A lint-free rag
sleeving of degaussing conductors? 4. A vacuum cleaner

1. Painting 9-73. What is the fastest and easiest way for you to
2. Branding check connection boxes or through boxes for
3. Notching moisture?
4. Stenciling
1. Remove the box cover
9-67. In the degaussing system, adjustments for 2. Remove the drain plug
ampere-turn ratios are made in what 3. Loosen the cable packing gland
component(s)? 4. Check the ground meter at the
switchboard
1. The degaussing switchboard
2. The remote control panel
3. The connection boxes
4. The through boxes

74
 ASSIGNMENT 10
Textbook Assignment: “Cathodic Protection,” “Visual Landing Aids,” “Engineering Plant Maintenance, Operations,
and Inspections,” and “Engineering Casualty Control,” chapters 11 through 14, pages 11-1
through 14-27.

10-6. Which of the following is NOT an advantage

Learning Objective: Identify the characteristics of of sacrificial anodes?
the cathodic protection system.
1. Hull protection
2. Ease of installment
10-1. What protection system is installed to reduce
3. Little maintenance required
corrosion or deterioration of a ship’s hull in
4. Reduced noise level around the hull
seawater?
10-7. What material is used to make the impressed
1. Armament
current cathodic protection system anodes?
2. Cathodic
3. Resistive
1. A carbon-coated rod
4. Degaussing
2. A silver-chloride coated rod
3. A platinum-coated rod
10-2. What is the electrolyte in a cathodic
4. A zinc-coated rod
protection system?
10-8. What is the current rating of a 4-foot anode?
1. Tricarboxylic acid
2. Sulfuric acid
1. 75 A
3. Salammoniac
2. 100 A
4. Seawater
3. 125 A
4. 150 A
10-3. Which of the following factors is used to
determine the amount of corrosion on a hull?
10-9. As used with cathodic protection systems, the
shaft grounding assembly grounds which of
1. The temperature of the seawater
the following components?
2. The resistivity of the seawater
3. Stray electrical currents
1. The electrical motor shafts
4. Each of the above
2. The propeller shafts
3. The generator shafts
10-4. What is the specified replacement period for
4. The air compressor shafts
the sacrificial type of anode?
10-10. What is the purpose of the large loop placed
1. 1 year
in a rudder grounding strap?
2. 2 years
3. 3 years
1. To reduce stray currents
4. 4 years
2. To ground the rudder crosshead
3. To permit full rotation of the rudder
10-5. What components are installed to protect
stock
valves and the sea chest?
4. To ensure the strap doesn’t get fouled on
the deck
1. Iron anodes
2. Aluminum anodes
3. Steel waster pieces
4. Magnesium pieces

75
10-11. What is the voltage range developed between 10-16. The stabilized GSI platform receives its
a disconnected platinum anode and the hull? reference signal to remain level from

1. 1.0 to 2.0 Vdc 1. the ship’s navigation gyro

2. 1.0 to 2.5 Vac 2. a gyro mounted on the platform
3. 2.5 to 3.5 Vac 3. the main IC switchboard
4. 3.0 to 5.0 Vdc 4. a 400-Hz static converter mounted in the
helicopter control station
10-12. What is the optimum polarization range of the
ships hull-to-reference electrode potential? 10-17. The GSI hydraulic pump supplies oil to the
hydraulic actuator at what specific pressure?
1. +1.0 to +2.0 Vdc
2. +0.80 to +0.90 Vdc 1. 1,000 psi
3. -0.80 to -0.90 Vdc 2. 1,200 psi
4. -1.0 to -2.0 Vdc 3. 1,400 psi
4. 1,600 psi

Learning Objective: Identify the components of 10-18. Which of the following components are
the visual landing aids and recognize their contained in the GSI lamp house assembly?
function.
1. Three source lights
2. A vent fan
10-13. Which of the following components make(s)
3. An optical lens
up the visual landing aids (VLAs) aboard air-
4. All of the above
capable ships?
10-19. The homing beacon is (a) what color lamp
1. Lighting
mounted on (b) what component?
2. Approach aid
3. Deck markings
1. (a) White (b) the mainmast
4. All of the above
2. (a) Red (b) the superstructure
3. (a) Red (b) the mainmast
10-14. Which of the following phrases describes the
4. (a) Blue (b) the superstructure
stabilized glide slope indicator (GSI) system?
10-20. Of the lists shown below, which one indicates
1. A mechanical light
the three colors of the GSI light bars?
2. A hand-held landing instrument
3. An electrohydraulic optical landing aid
1. Red, green, and white
4. A group of pulsating lights
2. Red, green, and amber
3. Blue, green, and white
10-15. The GSI functions in which of the following
4. Blue, green, and amber
ways?
10-21. Edge lights are red omnidirectional lamps that
1. The reference light mounted inside the
can be seen in any direction above deck level.
GSI is kept steady as the ship moves,
allowing the pilot to land safely
1. True
2. The helicopter is kept from pitching as it
2. False
leaves the deck
3. The error signal developed is fed to the
10-22. What color are the line-up lights?
gyro to allow it to remain steady
4. The GSI gives the pilot better depth
1. Red
perception when landing at night
2. Blue
3. White
4. Green

76
 10-27. II.
Learning Objective: Identify procedures for filling
out, handling, and using various engineering logs
1. A
and records.
2. B
3. C
10-23. Which of the following documents is/are 4. D
considered legal records?
10-28. Z.
1. Engineering Log
2. Engineer’s Bell Book 1. A
3. Both 1 and 2 above 2. B
4. Watch, Quarter, and Station Bill 3. C
4. D
10-24. Which of the following is information that
should be entered in the Engineering Log? 10-29. III.

1. Injuries to personnel within the 1. A

department 2. B
2. Mileage steamed for the day and fuel 3. C
expended 4. D
3. Major speed changes and average hourly
rpm 10-30. Neat corrections and erasures are permitted in
4. Each of the above the Engineer’s Bell Book if they are made
only by the person required to sign the record
10-25. The responsibility for the daily verification of for the watch and if the change is neatly
the accuracy and completeness of the initialed in the margin of the page.
Engineering Log rests with the
1. True
1. engineering officer of the watch 2. False
(EOOW)
2. engineering officer 10-31. For a list of the engineering records that must
3. executive officer be kept permanently, you would refer to what
4. commanding officer publication?

10-26. The responsibility for making entries in the 1. NSTMs

Bell Book rest with the 2. SECNAVINST P5212.5
3. NAVSHIPS 5083
1. throttleman 4. NAVSHIPS 3648
2. helmsman
3. chief engineer 10-32. What person enters remarks and signs the
4. officer of the deck record on the AC/DC Electric Propulsion
Operating Record?
A. AHEAD FLANK SPEED
B. AHEAD FULL SPEED 1. The leading EM
2. The electrical officer
C. STOP
3. The EM of the Watch
D. AHEAD STANDARD SPEED
4. The engineering officer

Figure 10A.

IN ANSWERING QUESTIONS 10-27 THROUGH 10-29,

MATCH THE FOLLOWING BELL BOOK ENTRIES
WITH THEIR MEANING SHOWN IN FIGURE 10A.

77
10-33. On small ships, the Gyrocompass Operating
Record and the I. C. Room Operating Record Learning Objective: Recognize the purpose of the
may be maintained on the same form. Planned Maintenance System (PMS) and identify
PMS forms and their uses.
1. True
2. False
10-38. Which of the following is NOT a use of the
PMS?
10-34. Which of the following is a purpose of
maintaining and retaining engineering
1. To provide a description of the methods
operating records and reports?
and tools to be used for maintenance
2. To provide for the detection and
1. To inform responsible personnel of
prevention of impending casualties
coming events
3. To estimate and evaluate material
2. To supply data for the analysis of
readiness
equipment
4. To forecast and plan for personnel and
3. To warn of impending casualties
material losses
4. Each of the above
10-39. Which of the following lists are categories of
10-35. Which of the following information is
the PMS?
contained in the engineer officer’s Night
Order Book?
1. Cycle, quarterly, and monthly
2. Quarterly, monthly, and weekly
1. Special instructions for the night
3. Cycle, monthly, and weekly
engineering officer
4. Cycle, quarterly, and weekly
2. Standing instructions for the night
engineering officer
10-40. The Quarterly PMS Schedule is updated by
3. Both 1 and 2 above
(a) what person at (b) what interval?
4. Procedures for lighting off equipment
1. (a) Work center supervisor (b) daily
10-36. Of the following personnel, which one is
2. (a) Work center supervisor (b) weekly
required to know the content of the Night
3. (a) Division officer (b) daily
Orders?
4. (a) Division officer (b) weekly
1. The leading duty petty officer of each
10-41. Completed Quarterly PMS schedules are kept
engineering division, when in port
on file for what minimum period of time?
2. The oil king
3. The principal watch supervisor of
1. 1 year
engineering departments for both at-sea
2. 2 years
and inport watches
3. 3 years
4. Each of the above
4. 6 months
10-37. Unless they are requested by a Naval Court or
10-42. The Weekly PMS Schedule is updated by
board or by the Navy Department, the
(a) what person at (b) what interval?
Engineering Log and Engineer’s Bell Book
are kept on board ship for what minimum
1. (a) Daily (b) workcenter supervisor
number of years?
2. (a) Weekly (b) workcenter supervisor
3. (a) Daily (b) division officer
1. 1
4. (a) Weekly (b) division officer
2. 2
3. 3
4. 4

78
10-43. The Weekly PMS Schedule contains blank 10-47. The amount of information required to be
space for the signature of what official? given to personnel doing a particular repair
job depends on which of the following
1. Engineer officer considerations?
2. Division officer
3. 3-M assistant 1. The safety precautions you expect them
4. Work center supervisor to ignore
2. The man-hours estimated to complete
the job
A. OPNAV 4790/2L
3. The experience of the personnel
B. OPNAV 4790/CK assigned to the job
C. OPNAV 4790/2K 4. The degree of care with which you
D. OPNAV 4790/2Q expect to inspect the job upon
completion
Figure 10B.
10-48. A careful inspection should be conducted
after a job has been completed to ensure that
IN ANSWERING QUESTIONS 10-44 THROUGH 10-46,
the work was properly performed and that
REFER TO FIGURE 10B AND SELECT THE MDS
necessary records or reports have been
OPNAV FORM THAT IDENTIFIES THE TITLE USED
prepared.
AS THE QUESTION.
1. True
10-44. Ship’s Maintenance Action Form.
2. False
1. A
10-49. Which of the following estimates is often the
2. B
most difficult for a supervisor to make in
3. C
arriving at a job completion time?
4. D
1. Tools required
10-45. Supplemental Form.
2. Materials required
3. Personnel required
1. A
4. Time and labor required
2. B
3. C
4. D Learning Objective: Identify the procedures and
responsibilities for the various inspections
10-46. Automated Ship’s Maintenance Action Form. conducted aboard ship.

1. A
2. B 10-50. What type of inspection is concerned mainly
3. C with a ship’s ability to carry out its wartime
4. D missions?

1. Administrative inspection of the ship as

Learning Objective: Recognize the factors a whole
involved in planning, estimating, and inspecting 2. Administrative inspection of the ship’s
work performed by others. departments
3. Operational readiness inspection
4. Material inspection

79
10-51. Which of the following types of inspections 10-55. In a shipboard battle problem, observers
include battle problems? should use equal effort to note excellence as
well as weakness.
1. Operational readiness inspections only
2. Material inspections only 1. True
3. Material inspections and operational 2. False
readiness inspections
4. Formal inspections 10-56. Unless they have a direct bearing on the
material condition, administrative methods
10-52. What is the primary purpose of a shipboard and cleanliness should not be considered as
battle problem? part of a material inspection.

1. To provide an opportunity for all hands 1. True

to participate, if they with to do so 2. False
2. To allow machinery testing
3. To provide a medium for testing and 10-57. Which of the following is a main inspection
evaluating the ability of all divisions to item for a material inspection of engineering
function together as a team spaces?
4. To allow senior personnel a chance to
pass along their knowledge 1. Procedures used for the replacement of
repair parts
10-53. The value of a battle problem to a ship’s 2. Installation and maintenance of required
company is directly proportional to which of fire-fighting equipment in the
the following factors? engineering spaces is done according to
up-to-date procedures
1. The amount of preparation time allowed 3. Maintenance of equipment custody
the ship’s company before zero problem cards
time 4. Knowledge by responsible engineering
2. The amount of realism provided in the personnel of current instructions
problem regarding routine testing and inspections
3. The skill of the observing party
evaluating the problem procedures 10-58. Which of the following trials are considered
4. The number of trained observers routine ship’s trials?
conducting the problem
1. Laying up, final acceptance, and
10-54. Under what circumstances are engineering recommissioning
telephone circuits used during the battle 2. Tactical, standardization, and post repair
problem? 3. Economy, post repair, and full power
4. Preliminary acceptance, economy, and
1. For the observing party to announce the builder’s
start and end of the problem
2. When the observing party spots an 10-59. What kind of trouble can be expected if a full
actual casualty power trial is held in shallow water?
3. When ship’s personnel spot an actual
casualty 1. Excessive speed
4. When the ship’s engineering personnel 2. Multiple pump failures
need to cope with the battle problem 3. Overloading of the propulsion plant
assigned to the ship 4. Foaming of lube oil in reduction gears

80
10-60. At what interval should readings be taken and 10-65. What is the maximum allowable time
recorded during an economy trial? between noise level surveys taken aboard
ship?
1. Every half hour
2. Every hour 1. 1 year
3. At the start and end of the trial 2. 2 years
4. At the start, middle, and end of the trial 3. 6 months
4. After each major yard period

Learning Objective: Recognize the importance of 10-66. On board ship, what person is responsible for
the Hearing Conservation Program and identify issuing aural protective devices?
hazards that may lead to hearing loss.
1. The duty corpsman
2. The main propulsion assistant
10-61. Exposure to what type of sounds can cause a
3. The engineering officer
hearing loss?
4. The division officer
1. Continued sounds only
10-67. Which of the following actions is the
2. Intermittent sounds only
engineering officer required to perform?
3. Continued and intermittent sounds
4. Sounds above 104 dB
1. Have newly reporting personnel receive
a hearing test
10-62. What is the purpose of the Hearing
2. Advise the medical department of
Conservation Program?
personnel who are working in noise
areas
1. To identify noise sources
3. Arrange for a noise survey to be taken
2. To reduce exposure of personnel to
4. Each of the above
potentially hazardous noises
3. To test the hearing of personnel exposed
10-68. Which of the following responsibilities would
to noise
be yours as a work center supervisor?
4. To provide hearing conservation devices
1. Posting safety signs in your work area
10-63. All personnel who are exposed to potentially
2. Training and counseling your personnel
hazardous noises may wear hearing devices at
on the effects of noise pollution
their own discretion.
3. Ensuring work center personnel have
hearing protection
1. True
4. Each of the above
2. False

10-64. What instruction sets the guidelines for the Learning Objective: Identify aspects of engineering
Secretary of the Navy’s policy on casualty control.
occupational safety and health?

1. OPNAVINST 4790.4 10-69. Which of the following is the primary

2. SECNAVINST 5100.1 objective of engineering casualty control?
3. SECNAWNST 6460.4
4. OPNAVINST 3120.32G 1. The prevention, minimization, and battle
casualties
2. To minimize personnel casualties
3. To maintain the efficiency of the
engineering department
4. To operate engineering equipment at
minimum efficiency

81
10-70. What is the most effective phase of casualty 10-73. EOSS is designed to improve the
control? operational readiness of the ship’s
engineering plant by increasing its
1. Restoration operational efficiency and providing
2. Training better engineering plant control.
3. Prevention
4. Communications 1. True
2. False
10-71. Which of the following is/are the cause of
most engineering plant casualties? 10-74. Continuous operation of equipment
under casualty conditions can be
1. Lack of effective communications authorized by which of the following
2. Lack of systems knowledge ship’s officers?
3. Improper procedures by watch standers
4. Both 2 and 3 above 1. Operations officer
2. Engineering officer
10-72. Which of the following examples is a reason 3. Officer of the watch
for an unsatisfactory grade on a casualty 4. Commanding officer
control drill?
10-75. One of the most important features of
1. Loss of plant control by the space the casualty power system is to provide
supervisor or the EOOW a means for temporary repairs.
2. Safety violations
3. Lack of knowledge of proper procedures 1. True
4. Each of the above 2. False

82