DNV Electrical Standard

OFFSHORE STANDARD
DNV-OS-D201
ELECTRICAL INSTALLATIONS
MARCH 2001
DET NORSKE VERITAS

FOREWORD
DET NORSKE VERITAS (DNV) is an autonomous and independent foundation with the objectives of safeguarding life, prop-
erty and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification and consultancy
services relating to quality of ships, offshore units and installations, and onshore industries worldwide, and carries out research
in relation to these functions.
DNV Offshore Codes consist of a three level hierarchy of documents:
— Offshore Service Specifications. Provide principles and procedures of DNV classification, certification, verification and con-
sultancy services.
— Offshore Standards. Provide technical provisions and acceptance criteria for general use by the offshore industry as well as
the technical basis for DNV offshore services.
— Recommended Practices. Provide proven technology and sound engineering practice as well as guidance for the higher level
Offshore Service Specifications and Offshore Standards.
DNV Offshore Codes are offered within the following areas:
A) Qualification, Quality and Safety Methodology
B) Materials Technology
C) Structures
D) Systems
E) Special Facilities
F) Pipelines and Risers
G) Asset Operation
Amendments April 2002

This Code has been amended, but not reprinted in April 2002. The changes are incorporated in the Web, CD and printable (pdf)
versions. The amendments are shown in red colour in the Web and CD versions.
All changes affecting DNV Offshore Codes that have not been reprinted, are published separately in the current Amendments
and Corrections, issued as a printable (pdf) file.
Comments may be sent by e-mail to rules@dnv.com

For subscription orders or information about subscription terms, please use distribution@dnv.com
Comprehensive information about DNV services, research and publications can be found at http://www.dnv.com, or can be obtained from DNV,
Veritasveien 1, N-1322 Høvik, Norway; Tel +47 67 57 99 00, Fax +47 67 57 99 11.
© Det Norske Veritas. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including
photocopying and recording, without the prior written consent of Det Norske Veritas.
Computer Typesetting (FM+SGML) by Det Norske Veritas.

Printed in Norway by GCS AS.
If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas, then Det Norske Veritas shall pay compensation to such person
for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided that the maximum compen-
sation shall never exceed USD 2 million.
In this provision "Det Norske Veritas" shall mean the Foundation Det Norske Veritas as well as all its subsidiaries, directors, officers, employees, agents and any other acting on behalf of Det
Norske Veritas.
Offshore Standard DNV-OS-D201, March 2001
Contents – Page 3
CONTENTS
CH. 1 INTRODUCTION .................................................5 J 200 Cable temperature ........................................................... 30

J 300 Choice of insulating materials ........................................ 30
Sec. 1 General................................................................... 7 J 400 Current rating.................................................................. 30
J 500 Correction factors ........................................................... 31
A. Introduction ............................................................................ 7 J 600 Parallel connection of cables .......................................... 31
A 100 Objectives ......................................................................... 7 J 700 Additional requirements for A.C. installations,
and special D.C. installations.......................................... 32
B. Normative References ............................................................ 7 J 800 Rating of cables .............................................................. 32
B 100 Standards........................................................................... 7
B 200 Reference documents........................................................ 7 Sec. 3 Equipment in General........................................ 34
C. Informative References........................................................... 7 A. General Requirements ..........................................................34
C 100 General.............................................................................. 7 A 100 References....................................................................... 34
D. Definitions .............................................................................. 7 B. Environmental Requirements ...............................................34
D 100 Verbal forms ..................................................................... 7 B 100 Inclinations ..................................................................... 34
D 200 Offshore units ................................................................... 7 B 200 Vibrations and accelerations........................................... 34
E. Abbreviations and Symbols.................................................... 8 B 300 Temperature and humidity.............................................. 34
E 100 Abbreviations.................................................................... 8
C. Equipment Ratings................................................................35
F. Documentation........................................................................ 8 C 100 Electrical parameters ...................................................... 35
F 100 General.............................................................................. 8 C 200 Maximum operating temperatures.................................. 35
CH. 2 TECHNICAL PROVISIONS ...............................9 D. Mechanical and Electrical Properties ...................................35

D 100 Mechanical strength........................................................ 35
Sec. 1 General................................................................. 11 D 200 Cooling and anti-condensation ....................................... 36
D 300 Termination and cable entrances .................................... 36
A. Introduction .......................................................................... 11 D 400 Equipment protective earthing........................................ 36
A 100 References....................................................................... 11 D 500 Enclosures ingress protection ......................................... 37
A 200 Application...................................................................... 11 D 600 Clearance and creepage distances................................... 37
Sec. 2 System Design...................................................... 12 E. Marking and Signboards.......................................................38

E 100 General............................................................................ 38
A. Power Supply Systems ......................................................... 12
A 100 General............................................................................ 12 F. Insulation ..............................................................................38
A 200 System voltages and frequency....................................... 13 F 100 Insulation materials......................................................... 38
B. Main Electric Power Supply System .................................... 14 Sec. 4 Switchgear and Controlgear Assemblies.......... 40
B 100 General............................................................................ 14
A. Construction..........................................................................40
C. Emergency Power Supply System........................................ 15 A 100 General............................................................................ 40
C 100 Emergency power and distribution ................................ 15
C 200 Transitional source.......................................................... 18 B. Power Circuits ......................................................................41
C 300 Emergency generators..................................................... 18 B 100 Power components in assemblies ................................... 41
B 200 Batteries .......................................................................... 42
D. Battery Installation ............................................................... 19 B 300 Additional requirements for high voltage
D 100 General............................................................................ 19 assemblies ....................................................................... 42
E. Generator Prime Movers ...................................................... 19 C. Control and Protection Circuits ............................................43
E 100 General........................................................................... 19 C 100 Control and instrumentation ........................................... 43
F. Electric Power Distribution .................................................. 20 D. Verification and Testing .......................................................43
F 100 Distribution in general .................................................... 20 D 100 General............................................................................ 43
F 200 Lighting........................................................................... 21
F 300 Shore connections ........................................................... 21 Sec. 5 Rotating Machines.............................................. 45
G. Protection.............................................................................. 22 A. General..................................................................................45
G 100 System protection ........................................................... 22
G 200 Circuit protection ............................................................ 22 A 100 References....................................................................... 45
G 300 Generator protection ....................................................... 23 A 200 Requirements common to generators and motors .......... 45
G 400 Transformer protection ................................................... 24 A 300 Instrumentation of machines........................................... 46
G 500 Motor protection ............................................................. 24
B. Additional Requirements for Generators..............................46
H. Control .................................................................................. 24 B 100 General............................................................................ 46
H 100 System control ................................................................ 24 B 200 Voltage and frequency regulation................................... 46
H 200 Motor control .................................................................. 26 B 300 Generator short circuit capabilities................................. 47
B 400 Parallel operation ............................................................ 47
I. Vessel Arrangement ............................................................. 26
I 100 General............................................................................ 26 C. Verification and Testing .......................................................47
I 200 Rotating machines, general............................................. 27 C 100 Factory testing ................................................................ 47
I 300 Battery installations ........................................................ 28
I 400 Cable routing................................................................... 29 Sec. 6 Power Transformers .......................................... 50
I 500 Lightning protection ....................................................... 29
A. General..................................................................................50
J. Cable Selection ..................................................................... 29 A 100 General............................................................................ 50
J 100 General............................................................................ 29 A 200 Design requirements for power transformers ................. 50
DET NORSKE VERITAS

Page 4 – Contents
B. Inspection and Testing.......................................................... 50 Sec. 11 Hazardous Areas Installations.......................... 71

B 100 General ............................................................................50
A. General..................................................................................71
Sec. 7 Semi-conductor Converters............................... 52 A 100 General ............................................................................71
A. General Requirements .......................................................... 52 B. Documentation...................................................................... 71
A 100 General ............................................................................52 B 100 General ............................................................................71
A 200 Mechanical requirements ................................................52
A 300 Design requirements, electrical, for semi-conductor C. Equipment Selection............................................................. 71
assemblies .......................................................................52 C 100 General ............................................................................71
C 200 Ex protection according to zones ....................................71
B. Testing .................................................................................. 52 C 300 Additional requirements for equipment
B 100 Testing.............................................................................52 and circuit design ............................................................72
Sec. 8 Miscellaneous Equipment.................................. 54 D. Installation Requirements .....................................................72
D 100 General ............................................................................72
A. General.................................................................................. 54 D 200 Wiring and termination ...................................................73
A 100 Battery boxes and lockers ...............................................54
A 200 Socket outlets and plugs..................................................54 Sec. 12 Electric Propulsion............................................. 75
A 300 Lighting equipment .........................................................54
A 400 Heating equipment ..........................................................55 A. General..................................................................................75
A 500 Cooking and other galley equipment ..............................55 A 100 General ............................................................................75
A 200 System design .................................................................75
Sec. 9 Cables .................................................................. 57 A 300 System capacity...............................................................75
A. Application ........................................................................... 57 A 400 Electric supply system ....................................................75
A 100 General ............................................................................57 A 500 System protection............................................................76
A 600 Control systems...............................................................76
B. General Cable Construction.................................................. 57
B 100 General ............................................................................57 B. Torsional Vibrations ............................................................. 77
B 100 General ............................................................................77
C. High Voltage Cables............................................................. 57 B 200 Vibration measurements .................................................77
C 100 General ............................................................................57 B 300 Steady state - torsional vibration.....................................77
B 400 Transient torsional vibration ...........................................77
D. Low Voltage Power Cables .................................................. 58
D 100 Cables rated 0.6/1 kV and 1.8/3 kV ................................58 C. Verification ...........................................................................78
D 200 Protective sheaths............................................................58 C 100 Factory testing or manufacturer’s testing........................78
D 300 Wire braid and armour ....................................................59
D 400 Switchboard wires...........................................................59 Sec. 13 Definitions ........................................................... 79
D 500 Lightweight electrical cables ..........................................59
A. Definitions ............................................................................79
E. Control Cables ...................................................................... 59 A 100 General ............................................................................79
E 100 Construction ....................................................................59 A 200 Operational conditions ....................................................79
A 300 Services ...........................................................................79
F. Instrumentation and Communication Cables ....................... 59 A 400 Installation.......................................................................80
F 100 General ............................................................................59 A 500 Area definitions...............................................................80
A 600 Hazardous area................................................................80
Sec. 10 Installation .......................................................... 60 A 700 Sources of power, generating station and
distribution ......................................................................81
A. General Requirements .......................................................... 60 A 800 Switchboard definitions ..................................................81
A 100 General ............................................................................60
A 900 Components and related expressions ..............................82
B. Equipment............................................................................. 60
B 100 Equipment location and arrangement .............................60 CH. 3 CERTIFICATION AND CLASSIFICATION. 83
B 200 Equipment enclosure, Ingress Protection........................60
B 300 Batteries ..........................................................................62 Sec. 1 Certification and Classification -
B 400 Protective earthing and bonding of equipment ...............62 Requirements...................................................... 85
B 500 Equipment termination, disconnection, marking ............63
A. General..................................................................................85
C. Cables ................................................................................... 63 A 100 Introduction.....................................................................85
C 100 General ............................................................................63 A 200 Certification and classification principles.......................85
C 200 Routing of cables ............................................................64 A 300 Assumptions....................................................................85
C 300 Penetrations of bulkhead and decks ................................64 A 400 Documentation requirements ..........................................85
C 400 Fire protection measures .................................................64
C 500 Support and fixing of cables and cable runs ...................65 B. Certification of Products.......................................................85
C 600 Cable expansion ..............................................................66 B 100 General ............................................................................85
C 700 Cable pipes ......................................................................66 B 200 Certificate types .............................................................85
C 800 Splicing of cables ............................................................67 B 300 Type approval .................................................................85
C 900 Termination of cables......................................................67 B 400 Certification requirements for electrical equipment .......86
C 1000 Trace or surface heating installation requirements .........68 B 500 Survey during construction .............................................86
D. Inspection and Testing.......................................................... 68 C. Survey During Installation and Commissioning...................87

D 100 General ............................................................................68 C 100 General ............................................................................87
D 200 Equipment installation ....................................................68 C 200 Site inspections ...............................................................87
D 300 Wiring and earthing ........................................................68 C 300 Function tests ..................................................................87
D 400 Distribution system properties ........................................69 C 400 Available documentation ................................................87
DET NORSKE VERITAS

OFFSHORE STANDARD
DNV-OS-D201
ELECTRICAL INSTALLATONS
CHAPTER 1
INTRODUCTION
CONTENTS PAGE
Sec. 1 General ....................................................................................................................................... 7
DET NORSKE VERITAS

Veritasveien 1, N-1322 Høvik, Norway Tel.: +47 67 57 99 00 Fax: +47 67 57 99 11
Ch.1 Sec.1 – Page 7
SECTION 1
GENERAL
A. Introduction 202 Other reference documents are given in Table B2.
A 100 Objectives Table B2 Normative references

101 This offshore standard provides principles, technical re- No. Title
quirements and guidance for design, manufacturing and instal- IEC 60092 Electrical installations in ships
lation of electrical installations on mobile offshore units and IEC 61892 Mobile and fixed offshore units - Electrical instal-
floating offshore installations. lations
102 The requirements of this standard are in compliance IEC Other IEC standards as referenced in the text
with relevant parts of SOLAS Ch.II-1 and the IMO MODU IMO MODU International Maritime Organisation - Offshore;
Code. Code 1989 Code for Construction and Equipment of Mobile
Offshore Drilling Units
103 The standard has been written for general world-wide SOLAS 1974 International Convention for the Safety of Life at
application. Governmental regulations may include require- Sea
ments in excess of the provisions by this standard depending
on the size, type, location and intended service of the offshore
unit/installation.
104 The objectives of this standard are to: C. Informative References
— provide an internationally acceptable standard of safety by C 100 General
defining minimum requirements for offshore electrical in- 101 Informative references are not considered mandatory in
stallations the application of the offshore standard, but may be applied or
— serve as a contractual reference document between suppli- used for background information.
ers and purchasers 102 Informative references are given in Table C1.
— serve as a guideline for designers, suppliers, purchasers
and regulators Table C1 Informative references
— specify procedures and requirements for offshore units or No. Title
installations subject to DNV Certification and Classifica-
tion. DNV-OS-E101 Drilling Plant
DNV-OS-E201 Hydrocarbon Production Plant
B. Normative References
D. Definitions
B 100 Standards
D 100 Verbal forms
101 The requirements in this standard are generally based on
applicable standards for ships and offshore units as issued by 101 Shall: Indicates requirements strictly to be followed in
the International Electrotechnical Commission (IEC). order to conform to this standard and from which no deviation
is permitted.
Guidance note:
102 Should: Indicates that among several possibilities one is
This implies primarily the 60092 series for ships, and 61892 recommended as particularly suitable, without mentioning or
(1 to 7) for offshore units.
excluding others, or that a certain course of action is preferred
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- but not necessarily required. Other possibilities may be applied
subject to agreement.
102 The publications listed in Table B1 and Table B2 in- 103 May: Verbal form used to indicate a course of action
clude provisions which, through reference in the text, consti- permissible within the limits of the standard.
tute provisions of this offshore standard. The latest issue of the
references shall be used unless otherwise agreed. D 200 Offshore units
103 Other recognised standards may be used provided it can 201 Column-stabilised unit: A unit with the main deck con-
be demonstrated that these meet or exceed the requirements of nected to the underwater hull or footings by columns.
the publications listed in Table B1 and Table B2.
202 Floating offshore installation: A buoyant construction
104 Any deviations, exceptions and modifications to the de- engaged in offshore operations including drilling, production,
sign codes and standards shall be documented and agreed be- storage or support functions, and which is designed and built
tween the supplier, purchaser and verifier, as applicable. for installation at a particular offshore location.
B 200 Reference documents 203 Mobile offshore unit: A buoyant construction engaged in
offshore operations including drilling, production, storage or
201 Applicable DNV publications are given in Table B1. support functions, not intended for service at one particular
offshore site and which can be relocated without major dis-
Table B1 DNV Rules, Standards and Recommended Practices mantling or modification.
No. Title 204 Offshore installation: A collective term to cover any
Rules for Classification of Ships construction, buoyant or non-buoyant, designed and built for
DNV-OS-D202 Instrumentation and Telecommunication Systems installation at a particular offshore location.
DNV-RP-A201 Standard Documentation Types 205 Self-elevating unit: A unit with movable legs capable of
DNV-RP-A202 Documentation of Offshore Projects raising its hull above the surface of the sea.
DET NORSKE VERITAS

Page 8 – Ch.1 Sec.1
206 Ship-shaped unit: A unit with a ship- or barge-type dis- MOU Mobile offshore unit
placement hull of single or multiple hull construction intended MSB Main switchboard
for operation in the floating condition. NC Normally closed
NEMA National Electrical Manufacturers Association
NO Normally open
E. Abbreviations and Symbols P Rated output
PE Protective earth
E 100 Abbreviations PVC Polyvinyl chloride
101 Abbreviations used are given in Table E1. R Temperature measurement by the resistance method
RMS, rms Root mean square
Table E1 Abbreviations RP/RPS Redundant propulsion/redundant propulsion sepa-
Abbreviation Full text rate (DNV class notations)
A.C. Alternating current RT Routine test
ACB Air circuit breaker S1 Continuos duty
AVR Automatic voltage regulator SCR Silicone controlled rectifier
CIBS Classification information breakdown structure T Temperature measurement by the thermometer
method
DB Distribution switchboard
TT Type test
D.C. Direct current
UPS Uninterruptible power supply
DYNPOS Dynamic positioning (DNV class notation)
XLPE Cross-linked polyethylene
EDB Emergency distribution board
EMC Electromagnetic compatibility
EN European norm
EPR Ethylene propylene rubber F. Documentation
ESB Emergency switchboard F 100 General
ETD Temperature measurement by the embedded tem-
perature detector method 101 The types of documentation that are normally produced
to document aspects covered by this standard are defined in
HSLC High speed light craft
DNV-RP-A201, mainly under:
IEC International Electrotechnical Commission
IMO International Maritime Organisation — E – Electrical
IP Ingress protection — Z – Multidiscipline
IR Infrared 102 For documentation requirements related to certification
IS Intrinsically safe and classification, see Ch.3.
MCB Miniature circuit breaker
MCT Multi cable transit
DET NORSKE VERITAS

OFFSHORE STANDARD
DNV-OS-D201
CHAPTER 2
TECHNICAL PROVISIONS
CONTENTS PAGE
Sec. 1 General ..................................................................................................................................... 11
Sec. 2 System Design.......................................................................................................................... 12
Sec. 3 Equipment in General............................................................................................................... 34
Sec. 4 Switchgear and Controlgear Assemblies.................................................................................. 40
Sec. 5 Rotating Machines.................................................................................................................... 45
Sec. 6 Power Transformers ................................................................................................................. 50
Sec. 7 Semi-conductor Converters...................................................................................................... 52
Sec. 8 Miscellaneous Equipment ........................................................................................................ 54
Sec. 9 Cables ....................................................................................................................................... 57
Sec. 10 Installation................................................................................................................................ 60
Sec. 11 Hazardous Areas Installations .................................................................................................. 71
Sec. 12 Electric Propulsion ................................................................................................................... 75
Sec. 13 Definitions................................................................................................................................ 79
DET NORSKE VERITAS

SECTION 1
GENERAL
A. Introduction 204 The requirements in this standard apply to:
A 100 References — all electrical installations with respect to safety for person-
101 Sec.2 to Sec.13 are identical to the corresponding sec- nel and fire hazard
tions of the Rules for Classification of Ships / High Speed, — all electrical installations serving essential or important
Light Craft and Naval Surface Craft, Pt.4 Ch.8. These sections services with respect to availability.
constitute the technical part of this standard.
205 With respect to the definition of ‘essential services’ in
102 References in Sec.2 to Sec.13 to the International Code Sec.13, the inclusion of propulsion and steering is only appli-
of Safety for High Speed Craft (IMO HSC Code) are not applicable for units dependent on manoeuvrability.
cable in the context of this standard.
206 The terms ‘accepted’, ‘acceptable’ and similar shall be
A 200 Application understood as:
201 The requirements of this standard have been specifically
aimed at mobile offshore units and floating offshore installa- — agreed between the supplier, purchaser and verifier, as ap-
tions of the ship-shaped, self-elevating and column-stabilised plicable, when the standard is used as a technical reference
design types, but may also be applied to other types of floating — accepted by DNV when the standard is used as basis for
constructions. assigning DNV class.
202 The requirements of this standard may also be applied to 207 The term ‘additional class notation’ and similar shall be
fixed offshore installations. understood as a reference to the unit’s service, e.g. drilling unit
203 When the terms ‘ship’ or ‘vessel’ are used, it shall be in- or production unit, or to special equipment or systems in-
terpreted as ‘offshore unit’ or ‘offshore installation’. stalled, e.g. dynamic positioning.
DET NORSKE VERITAS

SECTION 2
SYSTEM DESIGN
A. Power Supply Systems c) In any four wire distribution system the system neutral
shall be connected to earth at all times without the use of
A 100 General contactors.
101 General requirements d) System earthing shall be effected by means independent of
any earthing arrangements of the non-current-carrying
a) Electrical installations shall be such that the safety of pas- parts.
sengers, crew and ship, from electrical hazards, is ensured.
e) Transformer neutrals on the primary side shall not be
b) There shall be two mutually independent and self con- earthed on systems where a generator neutral is earthed.
tained electric power supply systems on board:
104 Types of distribution systems
— main electric power supply system
— emergency electric power supply system, except as re- a) A.C. power: The following distribution systems can be
quired in e) and C101. used (for exemptions see 105 and 106):
c) Fire, flood or other damage condition, in a space contain- — three-phase three-wire with high-resistance earthed
ing a source of electric power shall not render more than neutral
this source, associated main switchboards and transform- — three-phase three-wire with low-resistance earthed
ers, out of operation. neutral
d) Fire, flood or other damage condition, in any other space — three-phase three-wire with directly earthed neutral
not covered by c) shall not render any source of electric — three-phase three-wire with insulated neutral.
power or associated main switchboards out of operation b) In addition for all voltages up to and including 500 V A.C.:
(remote operation may be impaired). Nor shall more than
one lighting system be rendered inoperative (main or — three-phase four-wire with neutral earthed, but with-
emergency lighting system). out hull return (TN-S-system). Combined PE (protec-
e) Vessels without a dedicated emergency electric power tive earth) and N (system earth) is allowed between
supply system are accepted upon compliance with require- transformer and N-bus bar in first switchboard where
ments in C104. the transformer secondary side is terminated i.e. TN-
C-S-system
Guidance note: — single-phase two-wire with insulated neutral
For requirements concerning the location of the emergency — single-phase two-wire with one phase earthed at the
source of power and emergency switchboard, see C101. power source, but without hull return.
Additional class notations may have an impact on the power sup-
ply arrangement. c) D.C. power: The following distribution systems can be
used (for exemptions see 105 and 106):
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
— two-wire insulated
102 Environmental conditions — two-wire with one pole earthed at the power source
(without hull return)
a) The electrical installations shall normally be suitable for — single-wire with hull return as accepted in 105.
operation in those environmental conditions given in
Sec.3 B, and have an ingress protection rating as given in 105 Hull return systems
Sec.10 B200.
b) If means are arranged to control the environmental condi- a) The hull return system of distribution shall not be used for
tions, the installation may be designed for other conditions any purpose in a tanker, or for power, heating, or lighting
than those required by a) as long as the means arranged in any other ship.
have the same redundancy as the installation in the area b) Provided that any possible resulting current does not flow
served. directly through any gas hazardous spaces, the require-
c) Electrical installations in gas hazardous areas shall comply ments of 105 does not preclude the use of:
with the requirements in Sec.11, and any special require- — impressed current cathodic protective systems
ments set forth in the relevant rule chapters. — limited and locally earthed systems
Guidance note: — insulation level monitoring devices provided the cir-
For the requirements for ventilation and air conditioning, see culation current does not exceed 30 mA under the
I101. most unfavourable conditions.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- c) Where the hull return system is used, all final sub-circuits,
i.e. all circuits fitted after the last protective device, shall
103 System earthing be two-wire and special precautions shall be taken.
a) If the system neutral is connected to earth, means of dis- 106 System on tankers
connection shall be fitted so that the system earthing may
be disconnected for maintenance or insulation resistance a) Normally, earthed distribution systems shall not be used in
measurement. Such means shall be for manual operation tankers. The requirement of 106 does not preclude the use
only. of earthed intrinsically safe circuits.
b) In systems with earthed neutral, equalising currents in the b) Under conditions approved by the national authorities of
neutral earthing exceeding 20% of the rated current of the flag state, the use of one of the following earthed sys-
connected generators or transformers is not acceptable. tems may be used:
DET NORSKE VERITAS

— power supplied, control circuits and instrumentation — supply for lighting (including signal lamps), space
circuits where technical or safety reasons preclude the heaters in accommodation spaces, socket outlets, and
use of a system with no connection to earth, provided hand-held portable appliances and for control, com-
the current in the hull is limited to not more than 5 A munication and instrumentation equipment: 250 V.
in both normal and fault conditions
— limited and locally earthed systems, provided that any b) For High Speed, Light Craft and Naval Surface Craft, the
possible resulting current does not flow directly maximum distribution voltage is limited to 500 V, except
through any of the dangerous spaces for electric propulsion systems, where higher voltages are
— A. C. power networks of 1000 V root mean square accepted.
(line to line) and over, provided that any possible re-
sulting current does not flow directly through any of 203 Maximum control voltages
the dangerous spaces. For control equipment being a part of power and heating instal-
lations (e.g. pressure or temperature switches for start and stop
107 Special requirements for non-metallic craft of motors), the maximum voltage is 1000 V. However, control
voltage to external equipment is not to exceed 500 V.
a) All metal parts of a non-metallic craft should be bonded
together, in so far as possible in consideration of galvanic 204 Supply voltage variations
corrosion between dissimilar metals, to form a continuous
electrical system, suitable for the earth return of electrical a) Electric distribution systems shall be designed and in-
equipment and to connect the craft to the water when wa- stalled so that the voltage variations on main switchboards
ter-born. The bonding of isolated components inside the are maintained within these limits:
structure is not generally necessary, except in fuel tanks. Steady state
b) Each pressure refuelling point should be provided with a — ±2.5% of nominal A.C. system voltage
means of bonding the fuelling equipment to the craft. — ±12% of nominal D.C. system voltage on battery in-
c) Metallic pipes capable of generating electrostatic dis- stallations.
charges, due to the flow of liquids and gases shall be bond-
ed so they are electrically continuous throughout their Transient state
length and shall be adequately earthed.
— from –15% to +20% of nominal A.C. voltage
d) Secondary conductors provided for the equalisation of — ±25% of nominal D.C. battery voltage.
static discharges, bonding of equipment, etc., but not for
carrying lightning discharges shall have a minimum cross b) The requirement for maximum transient voltage shall also
section of 5 mm2 copper or equivalent surge current carry- be complied with due to load shedding or tripping of con-
ing capacity in aluminium. sumers and under fault conditions.
e) The electrical resistance between bonded objects and the c) After a transient condition has been initiated, the voltage
basic structure shall not exceed 0.05 Ohm except where it in a main distribution A.C. system shall not differ from
can be demonstrated that a higher resistance will not cause nominal system voltage by more than ±3% within 1.5 s. In
a hazard. The bonding path shall have sufficient cross-sec- an emergency distribution system the voltage shall not dif-
tional area to carry the maximum current likely to be im- fer from nominal system voltage by more than ±4% within
posed on it without excessive voltage drop. 5 s.
f) A main earth bar shall be defined and fitted at a convenient 205 Voltage drop in the distribution system
place on board. This earth bar shall be connected to a cop-
per plate with a minimum area of 0.2 m2 attached to the a) An A.C. distribution system shall be designed and in-
hull and so located that it is immersed under all conditions stalled so that the stationary voltage drop in supply to in-
of heel. dividual consumers, measured from the main switchboard
to the consumer terminals, does not exceed 6% of system
A 200 System voltages and frequency nominal voltage.
201 General b) A D.C. distribution system shall be designed and installed
a) Electric distribution systems shall operate within the volt- so that the stationary voltage drop in supply to individual
age and frequencies given in 202 to 207. This also applies consumers, measured from the battery distribution to the
to distribution systems where one or more generator prime consumer terminals, does not exceed 10% of system nom-
movers are driving other equipment. When the main pro- inal voltage.
pulsion engine is used as a generator prime mover, varia- c) Requirements for transient voltages on consumer termi-
tions caused by the wave motion or sudden manoeuvres nals during start or stop are not given. However, the sys-
including crash stop, shall not exceed the given limita- tem shall be designed so that all consumers function
tions. satisfactorily.
b) Voltage variations deviating from the above are accepted 206 System frequency
in systems or part of systems if these are intentionally de-
signed for the actual variations. a) The frequency variations on A.C. installations with fixed
c) All voltages mentioned are root mean square values unless nominal frequency shall be kept within the following lim-
otherwise stated. its:
202 Maximum system voltages — 95 to 105% of rated frequency under steady load con-
ditions
a) Except as stated in b) the following maximum voltages in — 90 to 110% of rated frequency under transient load
distribution systems apply: conditions.
— connected by permanent wiring: 15000 V b) For A.C. installations designed for variable system fre-
— for portable appliances, which are not hand-held dur- quency, all equipment and its protection subject to the var-
ing operation, and with connection by flexible cable iable frequency, shall be rated to operate within the design
and socket outlet: 1000 V limits throughout the frequency range.
DET NORSKE VERITAS

Guidance note: voltage and frequency variations exceeding the limits

See the Rules for Classification of Ships, Pt.4 Ch.3 regarding the specified in A200
prime movers' speed governor characteristics. For instrumenta- — ensuring minimum comfortable conditions of habita-
tion equipment, see DNV-OS-D202. bility which shall include at least adequate services for
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- cooking, heating, domestic refrigeration (except re-
frigerators for air conditioning), mechanical ventila-
207 Harmonic distortion tion, sanitary and fresh water
— for a duplicated essential or important auxiliary, one
a) Equipment producing transient voltage, frequency and being supplied non-electrically and the other electri-
current variations is not to cause malfunction of other cally (e.g. lubricating oil pump No. 1 driven by the
equipment on board, neither by conduction, induction or main engine, No. 2 by electric motor), it is not expect-
radiation. ed that the electrically driven auxiliary is used when
b) In distribution systems the total harmonic distortion in one generator is out of service
voltage waveform shall not exceed 5%, nor shall any sin- — in addition, the generating sets shall be such as to en-
gle order harmonics exceed 3%. sure that with any one generator, transformer or power
converter out of service, the remaining generating sets
c) The total harmonic distortion may exceed the values given or transformers shall be capable of providing the elec-
in b) under the condition that all consumers and distribu- trical services necessary to start the main propulsion
tion equipment subjected to the increased distortion level plant from a dead ship condition. The emergency
shall be documented to withstand the actual levels. source of electrical power may be used for the purpose
d) When filters are used for limitation of harmonic distortion, of starting from a dead ship condition if its capability
special precautions shall be taken so that load shedding or either alone or combined with that of any other source
tripping of consumers, or phase back of converters, do not of electrical power is sufficient to provide at the same
cause transient voltages in the system in excess of the re- time those services required to be supplied by C103,
quirements in 204. The generators shall operate within except fire pumps and steering gear, if any.
their design limits also with capacitive loading. The distri-
bution system shall operate within its design limits, also Guidance note:
when parts of the filters are tripped, or when the configu- Those services necessary to provide normal operational condi-
ration of the system changes. tions of propulsion and safety do not normally include services
such as:
Guidance note:
— thrusters not forming part of the main propulsion or steering
The documentation required in c) may consider the following ef- — windlass
fects: — mooring
— additional heat losses in machines, transformers, coils of — cargo handling gear
switchgear and controlgear — refrigerators for air conditioning.
— additional heat losses in capacitors for example in compen-
sated fluorescent lighting However, additional services required by a class notation will be
— resonance effects in the network added to the list of important services.
— functioning of instruments and control systems subjected to In regard to non-important load, the capacity of all generators can
the distortion be taken into consideration.
— distortion of the accuracy of measuring instruments and pro-
tective gear (relays)
— interference of electronic equipment of all kinds, for exam-
ple regulators, communication and control systems, posi- 102 System redundancy
tion- finding systems, radar and navigation systems.
a) The failure of any single circuit or bus bar section shall not
A declaration or guarantee from system responsible may be an endanger the services necessary for the vessel's manoeu-
acceptable level of documentation. vrability. The failure of any single circuit shall not cause
important services to be out of action for long periods.
Any single failure shall not render duplicated consumers
serving essential or important services inoperable.
b) If the secondary distribution is arranged as two separate
B. Main Electric Power Supply System systems each fed from one transformer or converter, pos-
sible duplicated essential or important consumers shall be
B 100 General divided between the two systems.
101 Capacity c) Each transformer required according to 101 shall be in-
stalled as a separate unit, with a separate enclosure.
a) The main power supply system shall have the capacity to
supply power to all services necessary for maintaining the Guidance note:
ship in normal operation without recourse to the emergen- Single failure means failure in any single circuit, feeder, trans-
cy source of power. former or part of switchboard within one bus tie section.
b) There shall be component redundancy for main sources of ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
power, transformers and power converters in the main
power supply system so that with any source, transformer 103 Three single core transformers
or power converter out of operation, the power supply sys- a) Three single core transformers may substitute a three-
tem shall be capable of supplying power to the following phase transformer.
services:
b) The installation of three single core transformers is consid-
— those services necessary to provide normal operation- ered equivalent to two three-phase transformers upon the
al conditions for propulsion and safety following: The three single core transformers shall each be
— starting the largest essential or important electric mo- installed in a separate enclosure, shall have separate
tor on board, except thrusters, without the transient switchgear and protection and separate cabling. The ca-
DET NORSKE VERITAS

pacity of two of the three single core transformers shall be C. Emergency Power Supply System
in accordance with 101.
C 100 Emergency power and distribution
Guidance note:
Three single core transformers installed in the same outer enclo- 101 Independent emergency power
sure, but provided with flame retardant partition walls between
each phase or core are accepted. a) The emergency electric power supply system shall be lo-
cated above the uppermost continuous deck and be readily
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- accessible from open deck. It shall not be located forward
of the collision bulkhead.
104 Control of distribution system
b) The emergency source of electrical power may be either a
a) The control systems for the electric distribution system generator or an accumulator battery.
shall be so arranged that neither single circuit nor compo- c) The emergency source of power shall be automatically
nent failures will render more than the controlled part out connected to the emergency switchboard in case of failure
of operation. of the main source of electric power, and within 45 s auto-
b) The arrangement shall be such that any single failure will matically supply at least the services required to be sup-
not endanger the duplicated essential services necessary plied by transitional power as listed in Table C1.
for the vessel's manoeuvrability and will not cause dupli- d) The emergency source of power shall not be used for sup-
cated important services to be out of action for long peri- plying power during normal operation of the vessel. Ex-
ods. ceptionally, and for short periods, the emergency source of
c) When the distribution system is equipped for remote oper- power may be used for blackout situations, starting from
ation, local means for operation of breakers shall be fitted. dead ship, short term parallel operation with the main
The local operation shall function independently of the re- source of electrical power for the purpose of load transfer
mote system. and for routine testing of the emergency source of power.
d) See F104 for power supply requirements for control sys- e) In order to ensure ready availability of the emergency
tems. source of electrical power, arrangements shall be made
where necessary to disconnect automatically non-emer-
Guidance note: gency circuits from the emergency switchboard to ensure
a) implies that a failure in a control system for one part of the dis- that electrical power shall be available automatically to the
tribution system shall not render other parts of the distribution emergency circuits.
system inoperable, for example failure in the control of one gen-
erator breaker shall not render other generator breakers inopera- f) If the emergency source of power is not in accordance with
ble, likewise for feeders to duplicated transformers etc. c), a transitional source of emergency electrical power,
suitably located for use in an emergency, with sufficient
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- capacity of supplying the consumers listed in Table C1,
105 Restoration of power may be accepted.
Where the source of electrical power is necessary for propul- g) Requirements for uninterrupted power for instrumentation
sion and steering of the ship, the system shall be so arranged and automation, see DNV-OS-D202.
that the electrical supply to equipment necessary for propul- h) For the requirements for battery powered systems, see
sion and steering, and to ensure safety of the vessel, will be D100.
maintained or immediately restored in case of loss of any one
of the generators in service. This means: Exception for mobile offshore units and high speed light craft
For mobile offshore units applying the IMO MODU Code, or
— where more than one generating set is necessary to cover craft applying the HSC Code, location of emergency supply
normal loads at sea, the power supply system shall be pro- system below uppermost continuous deck may be accepted
vided with suitable means for tripping or load reduction of provided easy access from a normally manned area. However,
consumers, and with provisions for automatic starting and the emergency source of power shall always be located above
connection to the main switchboard of the stand-by gener- worst damage waterline.
ator. If necessary, important consumers may be tripped in
order to permit propulsion and steering and to ensure safe- Independent of this requirement, MOUs shall be equipped with
ty. If the remaining on line generators are not able to per- transitional source supplying consumers as listed in Table C1.
mit propulsion and steering and to ensure safety, provision Exception for ships
shall be made for automatic starting and connection to the
main switchboard of the stand-by generator with automat- The requirement for emergency source of power applies to all
ic restarting of the essential auxiliaries. Connection of the cargo vessels with the following exemptions:
stand-by generator to the main switchboard shall be com-
pleted within 30s after loss of power — ships with one of the service restrictions notations R2, R3
and R4
— where one generator normally supplies the electrical pow-
er, provision shall be made, upon loss of power, for auto- — ships of less than 500 gross tonnage
matic starting and connection to the main switchboard of — fishing vessels.
the stand-by generator with automatic restarting of the es- Guidance note:
sential auxiliaries. Connection of the stand-by generator to For the requirements for an emergency generator, see 300.
the main switchboard shall be completed within 30s after
loss of power For the requirements for a transitional source of emergency elec-
trical power, see 200.
— it shall be ensured that the total starting current of motors
having automatic restart will not cause excessive voltage ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
drop or overcurrent on the installation.
102 Capacity
Guidance note:
See also G101 for overload protection and load shedding. a) The electrical power available shall be sufficient to supply
all services essential for safety in an emergency, due re-
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- gard being paid to simultaneous operation of all services,
DET NORSKE VERITAS

also taking into account starting currents and transitory na- erator, warning signs shall be fitted also stating the load of
ture of certain loads. the consumers.
b) Where the emergency source of electrical power is an ac-
cumulator battery it shall be capable of carrying the emer- 103 Services to be supplied
gency electrical load without recharging while
maintaining the voltage of the battery as required by A200. a) For High Speed, Light Craft and Naval Surface Craft see
the Rules for Classification of HS, LC and NSC Pt.5 Ch.1
c) When non-emergency consumers are supplied by the Sec.5 A204 and D205.
emergency source of power, it shall either be possible to
supply all consumers simultaneously, or automatic discon- b) For additional class notations, additional requirements
nection of non-emergency consumers upon start of the may apply.
generator shall be arranged. The system shall be so ar-
ranged that the largest consumer connected to the emer- c) For main class ships and main class MOUs the list of serv-
gency power supply system can be started at all times ices in Table C1 shall be supplied by an emergency source
without overloading the generator unless automatically of power and by a transitional source of power, if any, for
disconnected upon start of the emergency generator. the period listed.
d) Starting air compressors, preheaters and lubrication oil d) In a ship engaged regularly in voyages of short duration, a
pumps for the main engine or auxiliary engines may be lesser period than the 18 hour period specified in Table C1
equipped for automatic disconnection from the emergency is accepted, but not less than 12 hours.
switchboard. Such consumers necessary for starting from
dead ship, if supplied from the emergency source of pow- e) The emergency source of electrical power shall be capable
er, shall be possible to connect manually at the emergency of supplying simultaneously at least the services listed in
switchboard also when the emergency generator is run- Table C1 for the periods specified, if they depend upon an
ning. If they may cause overloading of the emergency gen- electrical source for their operation.
Table C1 Services to be supplied by an emergency source and by a transitional source, including required duration for main class
Duration of Duration of Duration of Duration of

Service Emergency power consumers in ships and MOUs emergency transitional emergency transitional
power, power, power, power,
ships (h) ships (h) MOU (h) MOU (h)
At every muster and embarkation station, for surviv-
al craft and their launching appliances, and at the 3 0.52) 18 1
area of water into which it is to be launched.
In all service and accommodation alleyways, stair-
ways and exits, personnel lift cars and personnel lift 18 0.52) 18 1
trunks.
In the machinery spaces and main generating sta- 18 0.52) 18 1
tions including their control positions.
In all control stations, machinery control rooms,
steering gear and at each main and emergency 18 0.52) 18 1
switchboard.
Emergency In all spaces from which control of the drilling proc-
lighting ess is performed and where controls of machinery
essential for the performance of this process, or de- 18 1
vices for the emergency switching-off of the power
plant are located.
At all stowage positions for firemen's outfits. 18 0.52) 18 1
At the fire pump referred to in this table and its start- 18 0.52) 18 1
ing position.
At the sprinkler pump and its starting position, if 18 0.52) 18 1
any.
At the emergency bilge pump and its starting posi- 18 0.52) 18
tion, if any.
On helicopter landing decks. 18 1
Escape lights Emergency lights required for escape from the ves- 1
sel, with integral batteries.
The navigation lights and other lights required by
COLREG the International Regulations for Preventing Colli- 18 0.52) 18 1
lights sions at Sea in force.
Structure Any signalling lights or sound signals that may be
marking required for marking of offshore structures. 96
One of the fire pumps required by SOLAS Reg. II-
2/4.3.1 and 4.3.3 (the Rules for Classification of
Fire pumps Ships, Pt.4 Ch.10 Sec.2 B200) if dependent upon the 18 18
emergency generator for its source of power. (SO-
LAS Reg. II-1/43.2.5)
The steering gear if required to be so supplied by the
Rules for Classification of Ships, Pt.3 Ch.3 Sec.2
Steering gear J900. (SOLAS Reg. II-1/43.2.6.1) 0.5
(For a ship of less than 10000 gross tonnage the du-
ration shall only be at least 10 minutes.)
DET NORSKE VERITAS

Table C1 Services to be supplied by an emergency source and by a transitional source, including required duration for main class
(Continued)
Duration of Duration of Duration of Duration of
emergency transitional emergency transitional
Service Emergency power consumers in ships and MOUs power, power, power, power,
ships (h) ships (h) MOU (h) MOU (h)
Ballast valves Ballast control and indicating system. 18
Any of the ballast pumps required powered by the
Ballast pumps emergency source of power. Only one of the con- 18
nected pumps need be considered to be in operation
at any time.
Watertight The remote control system for watertight doors and
doors and hatches. 0,5
hatches
Diving equip- Permanently installed diving equipment, if depend- 18
ment ent upon the unit's electrical power.
Means to bring the stabiliser wings inboard and in-
dicators on the navigating bridge to show the posi-
Stabilisers (if tion of the stabiliser wings if there is a danger of the - - - -
any) survival craft being damaged by the ship's stabiliser
wings (as required by the Rules for Classification of
Ships, Pt.3 Ch.6 Sec.2 J100)
The VHF radio installation required by SOLAS reg- 18
ulation IV/7.1.1 and IV/7.1.2.
If applicable:
the MF radio installation required by SOLAS regu-
lations IV/9.1.1, IV/9.1.2, IV/10.1.2 and IV/10.1.3
the ship earth station required by regulation IV/ 18
10.1.1
the MF/HF radio installation required by regulations
IV/10.2.1, IV/10.2.2, IV/10.1.2 and IV/11.1.
All internal communication equipment, as required,
Communica- in an emergency; shall include:
tion 4)
means of communication between the navigating
bridge and the steering gear compartment
means of communication between the navigating 181) 0.53) 18 1
bridge and the position in the machinery space or
control room from which the engines are normally
controlled
means of communication between the bridge and the
radio telegraph or radio telephone stations.
Intermittent operation of the daylight signalling
lamp, the ship's whistle, the manually operated call 181) 0.53)
points, and all internal signals that are required in an
emergency.
The shipborne navigational equipment as required
by SOLAS regulation V/12 (Rules for Classification
Navigation of Ships, Pt.4 Ch.11 Sec.3 A200), where such provi- 181)
sion is unreasonable or impracticable the Society
may waive this requirement for ships of less than
5000 gross tonnage.
The fire and gas detection and their alarm systems. 181) 0.53) 18 13)
Alarm systems The general alarm system. 18 0.53) 18 13)
The fire detection and alarm system, unless these 18
systems are supplied by separate batteries.
Intermittent operation of the manual fire alarms and
all internal signals that are required in an emergency 18 1
The capability to close the blow-out preventer and of
disconnecting the unit from the well head arrange- 18 1
ment, if electrically controlled.
1) Unless such services have an independent supply for the period of 18 hours from an accumulator battery suitably located for use in an emergency.
2) For this transitional phase, the required emergency electric lighting, in respect of the machinery space and accommodation and service spaces may be
provided by permanently fixed, individual, automatically charged, relay operated accumulator lamps.
3) Unless such services have an independent supply for the period specified from an accumulator battery suitably located for use in an emergency.
4) Means of communication according to the Rules for Classification of Ships, Pt.4 Ch.12 Sec.1 B.
104 Independent installation of power sources — applicable regulations are either IMO MODU Code or
IMO HSC Code. Alternatively an arrangement approved
The requirements for a separate emergency source of power in by the authorities of the flag state is accepted
101 and 102 may be omitted if the following conditions are
met:
DET NORSKE VERITAS

— the main source of electrical power is arranged so that it — the lighting and other services required by Table C1.
complies with the requirements for emergency installa- See notes to Table C1.
tions
— electrical power is ensured to be available with fire or b) A transitional source of emergency electrical power shall
flooding in any one space or division be located as required for emergency power in 101, unless
— at least two sources of main power are to comply with the it supplies power to consumers within the same space as
requirements for emergency power generation. Each of the transitional source itself.
these is to be located in a space separated from the other, c) For requirements for battery powered systems, see D100.
as required for the separation of main and emergency
sources of power. Both of these sources are to be treated C 300 Emergency generators
as emergency sources of power. 301 Prime mover for emergency generator
Guidance note: a) Where the emergency source of electrical power is a gen-
Observe the requirement in 101: The requirement for starting and erator, it shall be driven by a suitable prime mover having
loading within 45 s stated in 101 may be overruled by B105, i.e. independent auxiliary systems as for example fuel, venti-
30 s. Observe requirements for class notation E0 in the Rules for lation, lubrication, cooling etc. The fuel shall have a flash-
Classification of Ships, Pt.6 Ch.3. The required time for starting point of not less than 43°C.
and connecting a main generator is 30 s.
b) The prime mover shall be started automatically upon fail-
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- ure of the main source of electrical power supply.
c) Whenever the emergency source of power is not ready for
105 Emergency switchboard immediate starting, an indication shall be given in the en-
gine room or at a manned control station.
a) The emergency switchboard shall be installed as near as is 302 Protective functions of emergency generating sets
practicable to the emergency source of electrical power.
b) Where the emergency source of electrical power is a gen- a) The protective shutdown functions associated with emer-
erator, the emergency switchboard shall be located in the gency generating sets shall be limited to those necessary to
same space unless the operation of the emergency switch- prevent immediate machinery breakdowns.
board would thereby be impaired. b) Other protective functions such as overcurrent, differential
c) In normal operation, the emergency switchboard shall be protection, high temperature etc. shall, if installed, give
supplied from the main switchboard by an interconnecting alarm only, when the generator is started as an emergency
feeder. This feeder shall be protected against overload and source of power. The alarm shall be given in a normally
short circuit at the main switchboard, and shall be discon- manned location.
nected automatically at the emergency switchboard upon c) For use as a harbour generator, or in test mode, protection
failure of the supply from the main source of electrical as for normal generator shall be fitted. See G301.
power.
303 Starting arrangements for emergency generating sets
d) Where the emergency switchboard is arranged for the sup-
ply of power back to the main distribution system, the in- a) An emergency generating set shall be capable of being
terconnecting cable shall, at the emergency switchboard readily started in its cold condition at a temperature of 0ºC.
end, be equipped with switchgear suitable for at least short If this is impracticable, or the vessel is intended for opera-
circuit protection. tion at lower ambient temperatures, provisions shall be
e) The emergency switchboard and emergency distribution made for heating arrangements to ensure ready starting of
boards shall be as defined in Sec.1 and not be considered the generating sets.
as part of the main distribution system, even though sup- b) Emergency generating set shall be equipped with starting
plied from such during normal operation. devices with a stored energy capability of at least three
consecutive starts. A second source of energy shall be pro-
f) Technical requirements for functionality and construction vided for an additional three starts within 30 minutes, un-
for main switchboards, apply to emergency switchboards. less manual starting can be demonstrated to be effective.
g) Provision shall be made for the periodic testing of the c) Stored energy for starting shall be maintained at all times,
complete emergency system and shall include the testing and shall be powered from the emergency switchboard.
of automatic starting arrangements. All starting, charging and energy storing devices shall be
h) No accumulator battery, except the starting battery for the located in the emergency generator space. Compressed air
emergency generator prime mover, shall be installed in the starting systems may however be maintained by the main
same space as the emergency switchboard. or auxiliary compressed air system through a suitable non-
return valve fitted in the emergency generator space.
C 200 Transitional source d) If accumulator batteries are used for starting of the emer-
201 Transitional source of emergency electrical power gency generator prime mover, every such prime mover
shall have separate batteries that are not used for any pur-
a) The transitional source of electrical power, where required pose other than the operation of the emergency generating
by the relevant rule chapters shall consist of an accumula- set.
tor battery suitably located for use in an emergency. The e) If the emergency generator is equipped with an electronic
battery source shall be able to operate, without recharging, governor, electronic AVR, priming pumps or other auxil-
while maintaining the voltage of the battery throughout the iaries dependent upon electric power supply for a success-
discharge period as required by A200. The battery capaci- ful start, power supply to this equipment shall be in
ty shall be sufficient to supply automatically, in case of accordance with the requirements for energy for starting.
failure of either the main or the emergency source of elec-
trical power, for the duration specified, at least the follow- Guidance note:
ing services, if they depend upon an electrical source for If the emergency generating set is arranged so as not to be auto-
their operation: matically started, then manual starting may be permissible, such
DET NORSKE VERITAS

as manual cranking, inertia starters, manually charged hydraulic b) Each battery powered system is to have a separate charg-
accumulators, or powder charge cartridges, where it can be dem- ing device, suitable for the actual service. This may alter-
onstrated as being effective within 30 minutes. natively be:
When manual starting is not practicable, each emergency gener-
ating set may be equipped with starting devices with a stored en- — a charging device supplied from the vessel's primary
ergy capability of at least three consecutive starts. A second or secondary electric distribution. Such charging de-
source of energy may be provided for three additional starts with- vices are considered as important consumers
in 30 minutes. — a charging dynamo driven by one of the engines which
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- the battery normally supplies, except that this is not al-
lowed for auxiliary engines for emergency generator
304 Emergency generator used in port and emergency fire pump.
a) The emergency source of power may be used during time c) Each starting battery required by these rules shall have an
in port for the supply of the ship mains, provided the re- independent charging device.
quirements for available emergency power is adhered to at d) Each charging device is, at least, to have sufficient rating
all times. for recharging to the required capacity within 6 hours,
b) To prevent the generator or its prime mover from becom- while the system has normal load.
ing overloaded when used in port, arrangements shall be e) A battery charger shall have automatically regulated
provided to shed sufficient non-emergency loads to ensure charging and operate on floating service with the battery
its continued safe operation. and give trickle charging when the battery is fully charged,
or with change-over arrangement for full-(quick-)charging
c) The prime mover shall be arranged with fuel oil filters and and automatic trickle charging.
lubrication oil filters, monitoring equipment and protec-
tion devices as required for the prime mover for main pow- f) Charging devices shall be provided with suitable switch-
er generation and for unattended operation. gear and fusegear for protection against faults such as
short circuits, overloads and connection failures (e.g.
d) The fuel oil supply tank to the prime mover shall be pro- harmful overvoltage is not to occur, if the connection with
vided with a low level alarm, arranged at a level ensuring the battery is broken). The arrangement shall further be
sufficient fuel oil capacity for the emergency services for such that the charging devices can be disconnected for
the required period. maintenance purpose, without breaking the supply to con-
e) Fire detectors shall be installed in the location where the sumers fed by the battery.
emergency generator set and emergency switchboard are g) Provisions shall be made for preventing reverse current
installed. from the battery through the charging device.
f) Means shall be provided to readily change over to emer-
Guidance note:
gency operation.
When the charging dynamo is an A.C. generator (alternator), par-
g) Control, monitoring and supply circuits, for the purpose of ticular attention should be paid to ensure that no damage would
the use of the emergency generator in port shall be so ar- occur if the connection with the battery is broken.
ranged and protected that any electrical fault will not influ- ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
ence the operation of the main and emergency services.
When necessary for safe operation, the emergency switch- 103 Battery monitoring
board shall be fitted with switches to isolate the circuits.
An alarm shall be given at a manned control station if the
h) Instructions shall be provided on board to ensure that charging of a battery fails, the ventilation fails or if the battery
when the vessel is under way all control devices (e.g. is being discharged.
valves, switches) are in a correct position for the independ-
ent emergency operation of the emergency generator set
and emergency switchboard. These instructions are also to
contain information on required fuel oil tank level, posi- E. Generator Prime Movers
tion of harbour or sea mode switch if fitted, ventilation
openings etc. E 100 General
101 General
a) Each generator required according to B101 shall normally
D. Battery Installation be driven by a separate prime mover. Each generator shall
be driven by one engine, and one engine shall only drive
D 100 General one generator.
101 Capacity of accumulator batteries b) If a prime mover for a generator is also used for driving
Batteries that shall be used for power supply required by these other auxiliary machinery in such a way that it is physical-
rules shall be dimensioned for the time required for the intend- ly possible to overload the engine, an interlock or other ef-
ed function at an ambient temperature of 0°C, unless heating is fective means for preventing such overloading shall be
provided. arranged. The availability of the generator shall be at least
as for separately driven generators.
102 Battery powered systems c) When generators driven by reciprocating steam engines or
a) Continuous insulation monitoring with alarm, according steam turbines are used, and the operation of the boiler(s)
to G102, shall be installed for all insulated distribution depends on electric power supply, there shall be at least
systems. For battery systems not extending their circuits one generator driven by an auxiliary diesel engine or gas
outside a single panel, this requirement is waived. Insula- turbine on board, enabling the boiler plant to be started.
tion monitoring for battery systems for non-important sys- d) A generator driven by a main propulsion unit (shaft gener-
tems below 50 V and for other systems serving one ator) which is intended to operate at constant speed, e.g. a
function only, test lamps or similar without continuous system where vessel speed and direction are controlled
monitoring is accepted. only by varying propeller pitch, may be one of the required
DET NORSKE VERITAS

generators according to B101. There shall be at least one f) For multi-engine propulsion plants the capacity of the
generator driven by a separate prime mover. The capacity starting batteries is to be sufficient for 3 starts per engine.
of separately driven generators shall be sufficient to sup- However, the total capacity is not to be less than 12 starts
ply all essential and important services that can be expect- and need not exceed 18 starts.
ed to be simultaneously in use, regardless of the
operational mode of the vessel. This shall be possible 104 Starting arrangement for auxiliary engines
without utilising any emergency power source.
a) Electric starting arrangement for a single auxiliary engine
102 Governor characteristics not for emergency use, shall have a separate battery, or it
shall be possible to connect it by a separate circuit to one
Generator prime movers shall comply with the requirements in of the main engine batteries, when such are used according
the Rules for Classification of Ships, Pt.4 Ch.2 Sec.6. to 103.
Guidance note: b) Each auxiliary engine for an emergency fire pump is to
Governors on prime-movers shall be such that they will automat- have a separate battery.
ically maintain the speed within a transient variation of 10% and
a steady-state variation not exceeding 5% when rated load is sud- c) When the starting arrangement serves two or more auxil-
denly thrown off and when 50% load is suddenly thrown on, fol- iary engines, there shall at least be two separate batteries,
lowed after a short instant by the remaining 50% load, unless as specified for main engines in 103. The main engine bat-
other load changes are specified. teries, when such are used, can also be used for this pur-
Emergency generator sets shall satisfy the above governor con- pose.
dition even when their total consumer load is applied suddenly.
d) Each starting battery shall have sufficient capacity for at
Consideration may be given to the throwing on of loads in por- least three start attempts of each of the engines being nor-
tions of with the values differ from those stated above in order to mally supplied. The duration of each starting shall be tak-
reach 100% rated load condition. en as minimum 10 s. If the starting batteries are also used
However, application of the load in more than two steps shall for supplying other consumers, the capacity shall be in-
permitted only if the condition within the ship’s mains permit the creased accordingly.
use of such prime-movers, which can be loaded in more than two
load steps only and provided that this has already been allowed e) Power supply to electronic governors, AVRs and other
for at the design stage. necessary auxiliaries for auxiliary engines shall, if depend-
Each prime-mover shall be fitted with an emergency overspeed ent on external power, be arranged as required for starting
device which will operate at a speed of not more than 15% above arrangement in c).
the rated speed and has provision for tripping by hand.
Where the driven generators shall operate in parallel, the gover-
nor characteristics of the prime movers shall be such that within
the limits of 20% and 100% total load, the load on any generating F. Electric Power Distribution
set does not differ from its proportional share of the total load by
more than 15% of the rated load of the largest machine or 25% of F 100 Distribution in general
the rating of the individual machine in question.
101 General
a) All switchboards and consumers shall be fed via switch-
103 Starting arrangements for main engines gear so that isolation for maintenance is possible. Contac-
tors are not accepted as isolating devices.
a) For main engines there shall be at least two separately in-
stalled batteries, connected by separate electric circuits ar- b) Each essential or important consumer shall be connected
ranged such that parallel connection is not possible. Each to a main switchboard or distribution board by a separate
battery shall be capable of starting the main engine when circuit.
in cold and ready to start condition. c) Two or more units, supplied from the main generators and
b) When two batteries are serving a single main engine, a serving the same essential or important purpose shall be
divided between at least two distribution switchboards
change-over switch or link arrangement for alternative
connection of the starter motor with its auxiliary circuits to when such are used, each having a separate supply circuit
the two batteries shall be provided. from different sections of the main switchboard(s).
c) Starting arrangements for two or more main engines shall 102 Generator circuits
be divided between the two batteries and connected by
separate circuits. Arrangements for alternative connection a) Each generator shall be connected by a separate circuit to
of one battery to both (or all) engines can be made, if de- the corresponding switchboard.
sired. b) When a generator is used for direct supply to single con-
d) The batteries shall be installed in separate boxes or lockers sumers, more than one generator breaker is acceptable. In
or in a common battery room with separate shelves (not such cases, the generator shall be de-exited and all the gen-
above each other). erator's breakers opened, in case of short circuit between
the generator neutral point and the generator breakers.
e) Each battery shall have sufficient capacity for at least the
following start attempts of the engines being normally 103 Division of main bus bars
supplied:
a) The main bus bars shall be divided into at least two parts
— 12 starts for each reversible engine by use of at least a switch disconnector or other approved
— 6 starts for each non-reversible engine connected to a means. The generating sets and other duplicated equip-
reversible propeller or other devices enabling the en- ment shall be divided between the parts.
gine to be started with no opposing torque. b) If the vessel is not dependent of electric power for the pro-
The duration of each starting shall be taken as minimum pulsion, the division of the main bus bar is not required for
10 s. If the starting batteries are also used for supplying low voltage installations.
other consumers, the capacity shall be increased accord- c) Bus tie breakers with co-ordinated protective functions
ingly. will be required where main generators serve as emergen-
DET NORSKE VERITAS

cy sources of power. Special requirements for bus tie tion of the vessel. The emergency switchboard may be used as
breakers may apply for additional class notations. one of the secondary distribution systems.
104 Power supply to control circuits The following lighting is divided between at least two circuits,
one from the main and one from the emergency switchboard:
a) Power for control circuits shall generally be branched off
from the main circuit of a consumer, with exceptions as — lighting in the engine room and all control stations
specified in b). — lighting in saloons, alleyways, stairways leading up to the
life boat stations and helicopter deck.
b) Power for control circuits may be supplied by a control
distribution system with the following conditions: 202 Navigation lights switchboard
— the power supply to control circuits for two or more The main navigation lights shall be connected to a dedicated
units serving the same essential or important purpose distribution switchboard, placed on the bridge or in the chart
shall be divided between at least two different distri- room. This distribution switchboard shall not be used for other
bution systems, with the supply complying with B102 purposes, except that special signal lights such as anchor lights
— the power supply to each such distribution system and signal lights required by canal authorities can be supplied.
shall be from the same main switchboard and bus bar Guidance note:
section as the main circuits involved. Power supply Special national requirements may apply.
can also be taken from battery installations construct-
ed in accordance with the same requirements for re- ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
dundancy
— the power supply for the control circuit of each essen- 203 Power supply to navigation lighting
tial or important consumer is to have individual short
circuit protection. a) The navigation light switchboard (controller) shall be sup-
plied by two alternative circuits, one from the main source
F 200 Lighting of power and one from the emergency source of power. A
changeover switch shall be arranged for the two supply
201 Lighting redundancy circuits.
a) A main electric lighting system shall provide illumination b) For any cargo ship without automatic starting of the emer-
throughout those parts of the ship normally accessible to, gency generator and for all passenger ships, the emergen-
and used by, passengers or crew, and shall be supplied cy power to the navigation light shall be supplied by the
from the main source of electrical power. transitional source of power until the emergency generator
b) The arrangement of the main electric lighting system shall is supplying power.
be such that fire, flood or other casualty, in spaces contain- c) For vessels without emergency power the navigation light-
ing the main source of electrical power, associated trans- ing shall have battery backed up supply.
forming equipment, if any, the main switchboard and the
main lighting switchboard, will not render the emergency 204 Navigation light circuits
electric lighting system inoperative.
a) A separate circuit shall be arranged for each light connect-
c) The arrangement of the emergency electric lighting sys- ed to this switchboard with a multipole circuit breaker,
tem shall be such that fire, flood or other casualty, in spac- multipole fused circuit breaker or with a multipole switch
es containing the emergency source of electrical power, and fuses in each phase.
associated transforming equipment, if any, the emergency
switchboard and the emergency lighting switchboard, will b) The overload and short circuit protection for each of these
not render the main electric lighting system inoperative. circuits shall be correlated with the supply circuit to ensure
discriminative action of the protection devices.
d) If the main lighting is arranged as two separate secondary
systems, each fed from a separate transformer or convert- c) Each light circuit shall be provided with an automatic
er, then the main lighting shall be divided between the two monitoring device, giving visual indication in the event of
systems so that with one system out of operation, there re- failure of the light, and in the event of a short circuit, when
mains sufficient lighting to carry out all functions neces- the light circuit is switched on.
sary for the safe operation of the vessel.
F 300 Shore connections
e) Redundancy requirement for generators and transformers
supplying the main lighting system is given in B101. 301 General
f) For vessels where emergency source of power not is re- a) When supply from shore is used, the connection of the
quired, b) does not apply. However, the following lighting supply cable from shore shall generally be carried out by
shall be divided between at least two circuits from differ- suitable terminals placed in a switchboard or in a shore-
ent parts of the main switchboard: connection box with a permanent cable connection to a
switchboard.
— engine room lighting
— switchboard room lighting b) In the switchboard, the circuit shall, at least, be provided
— lighting in control room and of control positions with a switch. In the shore-connection box, switchgear and
— lighting in alleyways, stairways leading up to the boat protection as required for feeder circuits shall be installed,
deck and in saloons. except that overcurrent protection can be omitted if such
protection is installed in the main switchboard.
Exception c) If the shore connection is supplying power via the emer-
For mobile offshore units covered by the MODU Code, the re- gency switchboard, C105 d) shall be complied with. Fur-
dundancy requirement in d) may be replaced by a lighting in- ther, the shore connection breaker shall be fitted with an
stallation divided between two systems, built with redundancy interlock (e.g. undervoltage release sensing the voltage on
in technical design and physical arrangement, i.e. with one sys- the shore side of the breaker), so that the shore connection
tem out of operation, the remaining system shall be sufficient is disconnected before the emergency generator or transi-
for carrying out all the functions necessary for the safe operational source of power is connected.
DET NORSKE VERITAS

d) For A.C. systems with earthed neutral, terminals for con- Guidance note:
nection between the shore and ship’s neutrals shall be pro- Circuits for heating cables, tapes, pads, etc. should be equipped
vided. with earth fault breakers. See Sec.8 A400. For propulsion cir-
cuits, see Sec.12.
e) For circuits rated maximum 63 A, connection by socket
outlet can be used instead of shore-connection box. The ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
circuit is then to have overcurrent protection on the main
switchboard. 103 Battery circuits
f) Normally, high voltage shore connection circuits shall not
be used. a) Circuits connected to batteries above 12 V or above 1 Ah
capacity shall have short circuit and overcurrent protec-
Guidance note: tion. Protection may also be required for smaller batteries
National authorities may require changeover or interlocking sys- capable of creating a fire risk. Short circuit protection shall
tem, so arranged that the connection to shore cannot be fed from be located as close as is practical to the batteries, but not
the vessel’s generators. inside battery rooms, lockers, boxes or close to ventilation
holes. The connection between the battery and the charger
is also to have short circuit protection.
b) Connections between cells and from poles to first short
circuit protection shall be short circuit proof.
G. Protection c) The main circuit from a battery to a starter motor may be
carried out without protection. In such cases, the circuit
G 100 System protection shall be installed short circuit proof. Auxiliary circuits,
101 Overload protection which are branched off from the starter motor circuit, shall
be protected as required in a).
a) Load shedding or other equivalent arrangements shall be
provided to protect the generators, required by these rules, 104 Overvoltage protection
against sustained overload. Overvoltage protection shall be arranged for lower-voltage
b) In power distribution systems that might operate in differ- systems supplied through transformers from high-voltage sys-
ent system configurations, the load shedding shall be such tems.
arranged that necessary system protection is functioning in Guidance note:
all system configurations.
Direct earthing of the lower voltage system, or the use of voltage
Guidance note: limitation devices, are considered as adequate protection. Alter-
Overload protection may be arranged as load reduction or as the natively, an earthed screen between the primary and secondary
tripping of non-important consumers. Where more than one gen- windings may be used. See Sec.3 D400 regarding current and
erator is necessary to cover normal load at sea, then important voltage transformers.
consumers may be tripped, if necessary. ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
G 200 Circuit protection
102 Insulation fault
201 General
a) Each insulated, or high resistance earthed primary or sec-
ondary distribution system shall have a device or devices a) Each separate circuit shall be protected against overcur-
to continuously monitor the values of electrical insulation rent and short circuit.
to earth and to give an audible or visual indication in case b) All circuits serving essential or important functions shall
of abnormally low insulation values. However, audible or be separately protected.
visual indication can be omitted provided automatic dis-
connection is arranged. The circulation current generated c) Loss of protective functions shall either trip the corre-
by each device for insulation monitoring is not to exceed sponding equipment or give an alarm on a manned control
30 mA under the most unfavourable conditions. position, unless other specific requirements apply.
b) The requirements in a) shall be applied on all galvanic sep- d) Non-important motors rated less than 1 kW, and other
arated systems on board. Except for: non-important consumers, rated less than 16A, do not need
separate protection.
— dedicated systems for single consumers
— galvanic separated local systems kept within one en- e) Each final circuit supplying multiple socket outlets, multi-
closure. ple lighting fittings or other multiple non-important con-
sumers shall be rated maximum 16 A in 230 V systems, 30
c) On high voltage systems automatic disconnection shall be A in 110 V systems.
arranged for operation at 1/3 or less of the minimum earth f) The protective devices shall provide complete and co-or-
fault current. However, for systems with high-resistance dinated protection to ensure:
earthed neutral or isolated neutral, this disconnection can
be replaced with an alarm when the distribution system — continuity of services under fault conditions through
and equipment are dimensioned for continuous operation discriminative action of the protective devices
with earth fault. For the requirements for voltage class of — elimination of the fault to reduce damage to the sys-
high voltage cables dependent of system behaviour with tem and hazard of fire.
earth fault, see J103.
d) On low voltage systems with low-resistance or directly g) For non-important circuits, circuit breakers with insuffi-
earthed neutral automatic disconnection of circuits having cient breaking capacity can be used, provided that they are
insulation faults shall be arranged. This earth fault protec- co-ordinated by upstream fuses, or by a common upstream
tion shall be selective against the feeding network. For low circuit breaker or fuses of sufficient breaking capacity pro-
resistance earthed neutral systems the disconnection shall tecting the circuit breaker and connected equipment from
operate at less than 20% of minimum earth fault current. damage.
DET NORSKE VERITAS

h) No fuse, single pole switch or single pole circuit breaker d) In high voltage equipment, fuses shall not be used for
shall be inserted in an earthed conductor including earthed overcurrent protection of power feeder circuits. Fuses may
neutral. be used for short circuit protection provided they can be
i) All consumers other than motors shall be controlled by, at isolated and replaced without any danger of touching live
least, multi-pole switchgear, except that single pole parts.
switches can be used for luminaires or space heaters in dry 204 Short circuit protection
accommodation spaces where floor covering, bulkhead
and ceiling linings are of insulating material. The general requirements for circuit protection in 201, 202 and
203 apply with the following exceptions:
j) See Note 9) to Table B1 in Sec.10 for special requirements
for protection in different locations. — separate short circuit protection may be omitted for motors
serving different functions of the same non-important
Exception equipment for example the engine room crane may include
For special requirements for protection of steering gear cir- hoisting, slewing and luffing motors. Each motor should
cuits, see 502. have separate overload protection and controlgear
— separate short circuit protection may be omitted at the bat-
202 Capacity tery or generator end of short circuit proof installed cables.
a) The breaking capacity of every protective device shall be 205 Overcurrent protection
not less than the maximum prospective short circuit at the
point where the protective device is installed. a) Overcurrent protection shall not be rated higher or adjust-
b) The making capacity of every circuit breaker or switch in- ed higher (if adjustable) than the cable's current-carrying
tended to be capable of being closed, if necessary, on short capacity, or the consumers nominal current, whichever is
circuit, shall not be less than the maximum value of the less.
prospective short circuit current at the point of installation. b) The general requirements for circuit protection in 201, 202
and 203 apply with the following exceptions:
c) Circuit breakers in main switchboards are generally to be
selected according to their rated service short circuit overcurrent protection may be omitted for circuits supply-
breaking capacity. (ICS according to IEC 60947-2 Clause ing consumers having overcurrent protection in their con-
4) trolgear
this also applies to a circuit supplying a distribution
d) If the main switchboard is divided by a switch disconnec- switchboard with consumers having overcurrent protec-
tor or a circuit breaker according to F103a) the feeder tion in their controlgear, provided that the sum of the rated
breakers in the main switchboard may be selected accord- currents of the controlgears does not exceed 100% of the
ing to their rated ultimate breaking capacity. (ICU accord- supply cable's rating.
ing to IEC 60947-2 Clause 4)
206 Control circuit protection
e) Provided that the main switchboard is divided by a bus tie
circuit breaker according to F103 a) and that total discrim- The general requirements for circuit protection in 201, 202 and
ination (total selectivity) of generator circuit breaker and 203 apply with the following exceptions:
bus tie breaker are obtained, all circuit breakers in the
main switchboard may be selected according to their rated — protection may be omitted for monitoring circuits of auto-
ultimate breaking capacity. (ICU according to IEC 60947- matic voltage regulators
2 Clause 4) — secondary side of current transformers shall not be protect-
ed
f) Generator circuit breakers and other circuit breakers with — the secondary side of single phase voltage transformers
intentional short-time delay for short circuit release shall may be protected in one pole (phase) only
have a rated short-time withstand current capacity not less — separate protection may be omitted for control circuits
that the prospective short circuit current. (ICW according branched off from a feeder circuit with nominal rating lim-
to IEC 60947-2 Clause 4) ited to 16 A
g) Every protective device or contactor not intended for short — separate protection may be omitted for control circuits
circuit interruption shall be co-ordinated with the up- branched off from a feeder circuit with nominal rating lim-
stream protection device. ited to 25 A and when the control circuit consists of ade-
quately sized internal wiring only.
h) When a switchboard has two incoming feeders, necessary
interlocks shall be provided against simultaneously clos- Guidance note:
ing of both feeders when the parallel connected short cir- Adequately sized wiring means that the wiring shall withstand
cuit power exceeds the switchboards' short circuit normal load and short circuit without reaching extreme tempera-
strength. A short time parallel feeding as a "make before tures.
break" arrangement is accepted when arranged with auto- ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
matic disconnection of one of the parallel feeders within
30 s.
G 300 Generator protection
203 Fuses 301 Generator protection
a) Fuses above 320 A rating shall not be used as overload a) Generators shall be fitted with overcurrent protection; set
protection, but may be used for short circuit protection if so that the generator breaker trips at 110 to 125% of nom-
otherwise acceptable according to these rules. inal current, with a time delay of 20 to 120 s.
b) Fuses for overcurrent protection shall not be rated higher b) The short circuit trip shall be set at a lower value than the
than the cable's current-carrying capacity, or the consum- generator’s steady state short circuit current and with a
ers nominal current, whichever is less. time delay as short as possible, taking discrimination into
c) Used for short circuit protection, fuses can be rated higher account. Maximum 1 s.
than the full-load current, but not higher than expected c) Other forms for generator overload protection, for exam-
minimum short circuit current. ple winding over-temperature combined with power re-
DET NORSKE VERITAS

lays (wattmetric relays), may substitute overcurrent Guidance note:

protection provided the generator cables are sufficiently When choosing the characteristics of protection devices for pow-
protected. er transformer circuits it may be necessary to take current surge
into consideration.
d) Generators having a capacity of 1500 kVA or above, and
all high voltage generators, shall be equipped with suitable ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
protection, which in the case of short circuit in the gener-
ator or in the supply cable between the generator and its G 500 Motor protection
circuit breaker will de-excite the generator and open the
circuit breaker. Emergency generators are exempted. 501 Motor protection
e) Each generator arranged for parallel operation shall be a) The general requirements for circuit protection in 200 ap-
provided with a reverse-power relay with a time delay be- ply.
tween 3 s and 10 s, tripping the generator circuit breaker b) Overcurrent protection for motors may be disabled during
at: a starting period.
— maximum 15% of the rated power for generators driv- c) Overcurrent relays shall normally be interlocked, so that
en by piston engines they must be manually reset after a release.
— maximum 6% of the rated power for generators driven d) Short circuit and overload protection shall be provided in
by turbines. each insulated phase (pole) with the following exemp-
The release power is not to depart from the set-point by tions:
more than 50% at voltage variations down to 60% of the — for D.C. motors, overcurrent relay in one pole can be
rated voltage, and on A.C. installations at any power factor used, but this cannot then substitute overcurrent re-
variation. lease at the switchboard
f) Generator circuit breakers shall be provided with under- — for A.C. motors supplied by three-phase electric pow-
voltage release allowing the breaker to be closed when the er with insulated neutral, overload protection in any
voltage and frequency are 85 to 110% of the nominal val- two of the three phases is sufficient
ue. The undervoltage release shall release within the range — overcurrent release may be omitted for essential or
70 to 35% of it's rated voltage. important motors, if desired, when the motors are pro-
g) The arrangement of short circuit-, overcurrent- and reverse vided with overload alarm (for steering gear motors,
power relays shall be such that it is possible to reconnect see 502)
the circuit breaker within 30 s after a release, provided the — overcurrent release in the controlgear may be omitted
voltage is within the range 85 to 110% of the rated voltage. when the circuit is provided with a switch-board cir-
cuit breaker with overcurrent protection.
h) See Sec.5 A301 for requirements for temperature detectors Overcurrent protection may be omitted for motors fit-
in windings. ted with temperature detectors and being disconnected
i) Where start and stop and load sharing between generators, upon over temperature, provided the feeding cable is
is controlled by an automation system, it shall be arranged sufficiently protected.
that the following alarms are routed to a permanently e) See Sec.5 A301 for requirements for temperature detectors
manned position, or to the main alarm system, in the case in windings.
of unattended operation:
502 Steering gear protection
— power failure to the control system
— starting failure of prime mover a) Steering gear circuits shall be disconnected upon short cir-
— high and low frequency cuit only.
— high and low voltage.
b) Overcurrent and single phase operation (if three phase
Excessive percentage difference in loads (kVA or alterna- equipment) shall activate alarm in a manned control posi-
tively both kW and kVAr) taken by the generators, with tion.
the necessary time delay, when in symmetrical load shar- c) Trip due to time-delayed overcurrent relays with release
ing mode. current at least 200% of the full load current is accepted.
In addition compliance with other relevant requirements in d) Fuses used for short circuit protection of steering gear cir-
the Rules for Classification of Ships, Pt.6 Ch.3 may be re- cuits shall be rated 200 - 300% of the full load current.
quired.
j) For emergency generators special requirements apply. See
C302.
H. Control
G 400 Transformer protection
H 100 System control
401 Transformer protection
101 Emergency stop
a) Transformers shall be fitted with circuit protection as re-
quired by 200. a) Emergency stops of at least the following pumps and fans
shall be arranged from an easily accessible position out-
b) If the primary side of transformers is protected for short side the space being served. These positions should not be
circuit only, overcurrent protection shall be arranged on readily cut off in the event of a fire in the spaces served:
the secondary side.
c) The protection system is to include an overcurrent alarm if — fuel oil transfer pumps
a load diversity factor has been used when deciding the — fuel oil booster pumps
rating. The overcurrent alarm is to be initiated without any — other similar fuel pumps
time delay. Or alternatively co-ordinated with the overload — nozzles cooling pumps when fuel oil is used as coolant
protection relay to enable manual load shedding. The re- — fuel oil purifiers
quirement is only applicable to distribution transformers. — pumps for oil-burning installations
DET NORSKE VERITAS

— fans for forced draught to boilers erators circuit breakers, nor their instrumentation and
— all ventilation fans. signals, inoperative.
b) The means provided for stopping the power ventilation of g) Automatic connection of a generator after blackout shall
the machinery spaces shall be entirely separate from the only be possible when auxiliary contacts on all generator
means provided for stopping ventilation of other spaces. circuit breakers show directly that all generators are dis-
connected from the main switchboard.
c) Emergency stop of thrusters and propulsion motors shall h) For emergency generators, a trip of a control circuit pro-
be arranged from all control stations. tection shall not lead to uncontrolled closing of the gener-
d) Emergency stops shall be independent of any remote con- ator breaker against a live bus.
trol system.
104 Control power distribution systems
e) Requirements for emergency stop of other equipment are
given in other parts of the rules. a) The control power can be supplied from a battery installa-
tion arranged as required for starting batteries when the
102 Arrangement of emergency stop circuits switchboard's main bus bars can be divided in two or more
a) The arrangement of the emergency stop system shall be sections by circuit breakers or on-load switches.
such that no single failure will cause loss of duplicated es- b) An independent control power supply system shall be ar-
sential or important equipment. ranged for each of the switchboard sections and be ar-
ranged with change over possibilities.
b) Computer based emergency stop systems shall have facil-
ities to detect failures that will set the system inoperable, c) The control power circuit for each generator breaker shall
and give alarm to a manned position. See DNV-OS-D202, have separate short circuit protection.
Ch.2 Sec.1 C. d) Each auxiliary control power supply system is to have suf-
c) Alarm for loss of power will be required for normally open ficient stored energy for at least two operations of all the
emergency stop circuits. components connected to its section of the switchboard.
For switching off circuit breakers this applies for all circuit
Guidance note: breakers simultaneously, and without excessive voltage
Emergency stop systems may be based on both normally open drop in the auxiliary circuits, or excessive pressure drop in
(NO) and normally closed (NC) circuits, depending on the ar- pneumatic systems.
rangement and the function of the system to be stopped. Systems,
which can be stopped without any hazard, should be based on NC 105 Generator instrumentation
circuits, emergency stop of propulsion motors and thruster
should be based on NO circuits. a) At any control position for operation of a generator break-
er the following information and control signals shall be
easily and simultaneously observed by the operator:
103 Main and emergency switchboard control
— control signals for breaker open and breaker close
a) Power supply for control circuits for generators breakers — generator power (kw), if the generator is for parallel
and generator protection shall generally be branched off operation
from the main circuit (i.e. line side of the generator break- — generator current. Three separate simultaneous read-
er.). For exception, see 104. ings or alternatively one reading with a changeover
switch for connection to all phases. if changeover
b) The interlocking circuit and protection relays shall be ar- switch is used, the current reading shall be supplied by
ranged so that the generator circuit breaker is not depend- separate current transformers, not used for protection
ent of external power sources except for external power — generator voltage
supplies mentioned in 104. — generator frequency
c) Switchboards designed and constructed entirely for re- — bus bar voltage
mote operation, i.e. without or partly without local instru- — bus bar frequency
mentation and control devices on the switchboard, will be — adjustment device for speed of generator prime mov-
accepted. The remote control system shall comply with er.
DNV-OS-D202.
b) It shall be possible to synchronise each generator intended
d) Where the main switchboard is arranged for remote oper- for parallel operation with two different devices. Each
ation from a position outside the space containing the main such generator shall be able to be synchronised to its bus
switchboard, the main switchboard shall in addition be ar- bar by a synchronising device independent of any other
ranged for operation from a position within the space con- sections of the switchboard.
taining the main switchboard. This arrangement shall be
independent of the remote control outside the space con- Exception:
taining the main switchboard. Measuring devices and in- The speed set-point of any main engine driving a generator
strumentation positioned in the generators circuit breaker does not need to be accessible at the control position for
compartment do not need to be duplicated. the generator breaker.
e) One single, common control station for several generators 106 Main source of power and main switchboard in different
can be accepted provided that necessary precaution is tak- locations
en with respect to separation of each of the generators con- For generators installed in a space that does not have direct ac-
trol cabling, instrumentation and control circuits. The cess to the space where the generator breaker is installed, the
control station cabinet should not be used for any other generator cable shall have short circuit protection at both ends.
purposes. Where the rules require the main bus bar divid- The generator and generator driver shall be equipped with re-
ed, the control for each part of the main switchboard shall mote control and alarms as required by class notation E0.
be separated with flame retardant partitions, unless each
generator has it's own control system. 107 Sectioning of bus bars
f) Any casualty within one compartment containing a gener- a) Switchgear for sectioning of bus bars shall have sufficient
ator circuit breaker should not render any of the other gen- making and breaking capacity for the service for which it
DET NORSKE VERITAS

is intended. If wrong operation may cause damage, then c) Common starting arrangements for a group of motors (e.g.
instructions for correct operation shall be given by sign- a group of circulating fans for refrigerated cargo holds) are
board on the switchboard. It shall be clearly indicated subject to consideration in each case.
whether such switchgear is open or closed. d) Controlgear for motors shall be designed for the frequency
b) Undervoltage release of sectioning switchgear is not ac- of making and breaking operations necessary for the re-
cepted unless the switchgear has sufficient capacity for spective motor.
breaking the prospective fault current at the point of instal- e) Switchgear for feeder circuits shall not be used as motor
lation. controlgear unless:
108 Parallel incoming feeders — the switchgear is designed for the frequency of mak-
a) Switchboards that are arranged for supply by two (or ing and breaking operations necessary for the respec-
more) alternative circuits shall be provided with interlock tive motor
or instructions for correct operation by signboard on the — the requirements for motor controlgear otherwise are
switchboard. Positive indication of which of the circuits is complied with
feeding the switchboard shall be provided. — the switchgear shall be of the withdrawable type if low
voltage.
b) When a secondary distribution switchboard is supplied by
two or more transformers or rectifiers, the circuit from 202 Power for motor starting
each of these shall be provided with multipole switchgear.
a) If the starting of a large motor requires that two or more
c) Switchboards supplied from power transformers shall be generators are run in parallel, an interlock shall be provid-
arranged with interlock or signboard as in a) unless the ed, ensuring that this circuit can only be switched on when
power transformers are designed for parallel operation. a sufficient number of generators are connected.
d) Interlocking arrangements shall be such that a fault in this b) The interlock may, however, be omitted for motors that
interlocking system cannot put more than one circuit out can only be started from the room where the generator
of operation. breakers are located, provided signboards with the neces-
e) In the case where a secondary distribution system is sup- sary instructions are fitted at the starters.
plied by parallel operated power transformers, supplied by
different sections of main bus bars, necessary interlocks
shall be arranged to preclude parallel operation of the
transformers when the main distribution bus ties are open I. Vessel Arrangement
or being opened.
I 100 General
f) Transformers shall not be energised from the secondary
side, unless accepted by the manufacturer. For high volt- 101 Ventilation
age transformers, secondary side switchgear shall general- a) All rooms where electrical equipment is located shall be
ly be interlocked with the switchgear on the primary side. sufficiently ventilated in order to keep the environmental
This so that the transformer will not be energised from the conditions within the limits given in Sec.3 B300.
secondary side when the primary switchgear is opened. If
backfeeding through transformers is arranged, special b) The heat generated by the electrical equipment itself, by
warning signs shall be fitted on the primary side switch- other machinery and equipment, and the heat caused by
gear. Different generators shall not feed the different sides sun radiation on bulkheads and decks should not lead to
of transformers simultaneously (not locking generators in operating ambient temperatures in excess of the limits list-
synchronism via a transformer). ed in Sec.3 Table B1.
Guidance note: c) The air supply for internal cooling of electrical equipment
(i.e. "ventilated equipment") shall be as clean and dry as
Temporary back-feeding as part of a black-start procedure may practicable. Cooling air shall not be drawn from below the
be accepted.
floor plates in engine and boiler rooms.
d) If forced ventilation or cooling is required, the same re-
dundancy requirement applies to such equipment and its
H 200 Motor control power supply as to the electrical equipment installed in the
201 Controlgear for motors ventilated or cooled area.
e) If the actual ambient air temperatures will clearly exceed
a) Each motor shall normally be provided with at least the the limits listed in Sec.3 Table B1, then the equipment
following controlgear, functioning independent of con- shall be designed for the actual operating ambient temper-
trolgear for other motors: atures concerned.
— each motor rated 1 kW or above: a multipole circuit 102 Arrangement of power generation and distribution sys-
breaker, fused circuit breaker or contactor, with over- tems
current release according to G500, if necessary com-
bined with a controller for limiting the starting current a) The integrity of the main electrical supply shall not be af-
— each motor rated 1 kW or above: control circuits with fected by fire, flood or other damage conditions, in one
undervoltage release so that the motor does not re- space only. The main switchboard shall be located as close
start after a blackout situation as is practicable to the main generating station.
— each motor rated less than 1 kW: a multipole switch. b) The main generating station shall be situated within the
machinery space, i.e. within the extreme main transverse
For exemptions and additions regarding steering gear mo- watertight bulkheads. Where essential services for steer-
tors, see G502. ing and propulsion are supplied from transformers, con-
b) Undervoltage release shall not inhibit intended automatic verters and similar appliances constituting an essential
restart of motor upon restoration of voltage after a black- part of electrical supply system they shall also satisfy the
out. foregoing.
DET NORSKE VERITAS

c) The integrity of the emergency electrical supply and the 104 Arrangement for high voltage switchboard rooms
transitional source of power shall not be affected by fire,
flood or other casualty in the main electrical supply, or in The space where high voltage switchboards are installed shall
any machinery space of category A. The emergency be so arranged that hot gases escaping from the switchboard in
switchboard shall be located in the same space as the case of an internal arc are led away from an operator in front of
emergency generating station. the switchboard.
d) Normally, the space containing the emergency source of 105 Passage ways for main and emergency switchboards
power and associated electrical distribution shall not be
continuous to the boundaries of machinery space of cate- a) Passages in front of main switchboards shall have a height
gory A or those spaces containing the main source of elec- of minimum 2 m. The same applies to passages behind
trical power and associated electrical distribution. switchboards having parts that require operation from the
rear.
e) All charging and energy storing devices for necessary con-
trol and instrumentation shall be located in the same space b) The width of the front passage shall be at least 0.8 m for
as the system being under control. UPSs or battery systems low voltage, and 1 m for high voltage switchboards. When
for operation of the main power distribution shall not be doors in high voltage cubicles are open there shall be at
located together with equipment necessary for operation least 0.5 m free passage left. The width of the passage be-
of the emergency power generation or distribution, or vice hind a switchboard where access for operation is neces-
versa. sary, shall be at least 0.6 m, except at frames where it can
be reduced to 0.5 m. Doors in open position, or switchgear
Guidance note: drawn out in position for service, shall not obstruct the
Any bulkhead between the extreme main transverse watertight passage, i.e. there shall be at least 0.4 m free passage left.
bulkheads is not regarded as separating the equipment in the (For high voltage there shall be 0.5 m left.).
main generating station provided that there is access between the
spaces. c) Where switchgear needs passage behind for installation
and maintenance work the free passage behind the switch-
The requirements in a) do not preclude the installation of supply gear shall not be less than 0.6 m, except at frames where it
systems in separate machinery spaces, with full redundancy in
technical design and physical arrangement. can be reduced to 0.5 m. For voltages above 500 V up to
and including 1000 V these figures for passage behind a
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- switchboard shall be increased to at least 0.8 and 0.6 m, re-
spectively.
103 Installation of switchboards
d) The free passageway in front of, or behind the switch-
a) Switchboards shall be placed in easily accessible and well- board, shall give unobstructed access to a door for easy es-
ventilated locations, well clear of substantial heat sources cape in case of an emergency situation occurring in the
such as boilers, heated oil tanks, and steam exhaust or oth- switchgear room.
er heated pipes. The ventilation shall be so arranged that
possible water or condensation from the ventilator outlets 106 Distribution switchboards
can not reach any switchboard parts.
a) Distribution switchboards shall be placed in accessible
b) Normally, pipes shall not be installed above, or immedi- spaces with enclosures as specified in Sec.10.
ately below, in front of or behind switchboards. If this is
unavoidable, additional screening of pipes and fittings will b) Alternatively switchboards may be placed in cupboards
be required in order to protect the switchboard against made of or lined with material that is at least flame-retard-
splash, or spray, by leakage. Such screening shall be pro- ant, and with door, cable entrances and other openings
vided with drains, if necessary. (e.g. for ventilation) arranged so that the cupboard in itself
c) Switchboards shall not be located immediately above complies with the protection required in Sec.10.
spaces where high humidity or high concentrations of oil c) The front of the switchboard, inside such a cupboard, is to
vapours can occur (e.g. bilge spaces), unless the switch- comply with enclosure type IP 20 with exemption for fus-
board has a tight bottom plate with tight cable penetra- es as specified in Sec.4 A104.
tions.
d) The arrangement and installation of switchboards shall be 107 Controlgear for equipment in bunker and cargo spaces
such that operation and maintenance can be carried out in All lighting and power circuits terminating in a bunker or cargo
a safe and efficient way. When switchgear is located close space shall be provided with a multiple pole switch outside the
to bulkheads or other obstructions, it shall be possible to space for disconnecting such circuits.
perform all maintenance from the front.
108 Hazardous areas
e) Switchboards more than 7 m long shall not form dead end
corridors. Two escape routes shall be available as required For installations in hazardous areas, as for example battery
by the Rules for Classification of Ships, Pt.4 Ch.10 Sec.15 rooms, paint stores, gas bottle stores or areas that may be haz-
B401.5 (SOLAS Reg. II-2/45.1). ardous due to the cargo or processes onboard, the requirements
in Sec.11 shall be complied with.
f) Type tested assemblies or partially type tested assemblies
with smaller clearance or creepage distances than given in I 200 Rotating machines, general
Sec.3 D600 (i.e. as accepted by Sec.4 A110), are not ac-
cepted installed in machinery space category "A". a) Generating sets with horizontal shaft shall generally be in-
g) If the installation prohibited in b) is unavoidable, then ad- stalled with the shaft in the fore-and-aft direction of the
ditional screening of pipes and fittings is required in order vessel.
to protect the electrical equipment against splash by leak- b) Where a large machine is installed athwartships, it should
age. Such screening shall be provided with drains, if nec- be ensured that the design of the bearings and the arrange-
essary. ments for lubrication are satisfactory to withstand the roll-
h) For water-cooled electrical equipment seawater pipes ing specified in the Rules for Classification of Ships, Pt.4
shall be routed away from the equipment, so that any leak- Ch.1 Sec.3 B. The manufacturer should be informed when
age in flanges do not damage the equipment. a machine for installation athwartships is ordered.
DET NORSKE VERITAS

I 300 Battery installations air outlet shall be arranged in the upper part so that gas
pockets cannot accumulate.
301 Application
These requirements are applicable for rechargeable batteries of Table I1 Battery location and ventilation
both "vented" and "dry" type batteries. Battery Minimum requirements for location and
capacity, ventilation
Guidance note: (KVAh)
The term "vented" batteries is used for rechargeable batteries Vented type Dry
with wet electrolyte without devices for reduced emission of gas. type
The term "dry" batteries is used for rechargeable batteries with > 20 > 40 Location: Dedicated battery room.
reduced emission of gas, such as valve regulated, sealed, gel type Ventilation:
Separate mechanical ventilation with suc-
or dry type batteries. Variants characterised as “sealed” or “her- tion fan, for minimum 30 changes of air per
metically sealed” should be regarded similar to the dry types un- hour.
less other properties are confirmed. The ventilation fan shall be started automat-
ically when full (quick) charging is com-
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- menced, and shall be running until at least
30 minutes after the charger unit has been
302 Hazardous area de-energised.
The ventilation fan shall be interlocked
a) No electrical equipment, except that necessary for opera- with the charger unit in such a manner that
tion and being certified safe for zone 1, hydrogen atmos- the charger unit is de-energised if the venti-
lation fails.
phere (gas group IIC), shall be installed inside battery
rooms, lockers or boxes. > 5 and < 20 N/A Location: Dedicated battery room or locker.
Ventilation:
b) Motors mounted inside extract ventilation ducts for lock- Mechanical ventilation as described above
ers and battery rooms, shall be certified safe as for a). The or natural ventilation to free air.
Natural ventilation shall be through an un-
fan itself shall be of non-sparking type. obstructed duct not inclined more than 45°
c) Battery rooms and lockers or boxes shall be regarded as from the vertical. The natural escape of air
shall not be reduced by the room ventilation
zone 2 hazardous areas with respect to access doors and system; i.e. the room is to have positive air
possible interference with other rooms. pressure. Lockers may be located in engine
rooms and similar spaces.
303 Arrangement <5 < 40 Location: Dedicated battery box.
Ventilation:
a) Requirements for the location of batteries depends upon Natural ventilation directly to the room by
their capacity as shown in 304 Table I1. ventilation holes at top and bottom.
The room is to have an extract ventilation
b) Accumulator batteries shall be suitably housed, and com- duct at ceiling level. The area of the room
partments shall be properly constructed and efficiently (m2), shall be at least 0.3 times battery
kVAh. Ventilation rate of the room shall be
ventilated. at least 6 air changes per hour.
— the batteries shall be so located that the their ambient N/A < 0.2 In ventilated electrical assemblies.
temperature remains within the manufacturer’s speci- Guidance note:
fication at all times. Normally, a location at open deck As an alternative to the above ventilation rates, the following
exposed to sun and frost will not be accepted may be applied:
— battery cells shall be placed so that they are accessible Ventilation rate, (m3/hour), for battery rooms and rooms contain-
for maintenance and replacement ing battery boxes:
— in battery boxes, the cells shall be placed at one height — for vented batteries, 10 x sum of battery kVAh.
only. There shall be minimum 300 mm space above — for dry batteries, 2 x sum of battery kVAh.
each cell when the top cover is open
For vented batteries, a two step ventilation system applying re-
— in battery rooms and lockers and boxes with side cov- duced ventilation rate at trickle charging may be applied if the ac-
er, there shall be a minimum of 300 mm space above tual charging current is monitored. The monitoring circuit shall
each cell automatically switch to high ventilation rate when the value of
— normally, accumulator batteries shall not be located in the charging current in amperes, rises above 2% of the battery
ampere hours value. Switching to low ventilation rate shall be by
sleeping quarters manual operation. The low ventilation rate, (m3/hour) shall be at
— only batteries for starting of the emergency generator, least 0.002 x sum of battery VAh.
if any, shall be installed in the same space as the emer- In case of natural ventilation by openings to the room or by ex-
gency switchboard. tract duct to free air, the following is given for cross section
(cm2) of openings and duct. Except for boxes, the inlet shall be
304 Ventilation of battery rooms of same size as the outlet.
— for dry batteries, 20 x battery kVAh.
a) Ventilation shall be arranged for all battery rooms, lockers — for vented batteries, 50 x battery kVAh.
and boxes. The air intake shall be in the lower part and can — for dry batteries located in electrical panels, 500 x battery
be taken from an adjacent room being readily accessible kVAh.
from the battery installation (e.g. ventilation from the en-
gine room, for batteries with access from this room). The ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
DET NORSKE VERITAS

305 Charging station for battery powered fork lift a) Where it is required to divide a ship into fire zones cable
runs shall be arranged so that fire in any main vertical fire
a) A charging station is defined as a separate room, only used zone will not interfere with essential services in any other
for this purpose, or a part of a large room, for example a such zone.
cargo hold, based on the area occupied by the fork lift plus
1 m on all sides. b) The cables for duplicated steering gear motors are to be
separated throughout their length as widely as is practica-
b) Socket outlets for the charging cables, mechanically or ble. This also applies to control circuits for the steering
electrically interlocked with switchgear, can be placed in gears motor starters, and to cables for remote control of the
the charging station. Such socket outlets shall have at least rudder from the bridge.
enclosure IP 44 or IP 56, depending upon the location (see
Sec.10 Table B1). In general no other electrical equip- c) Special attention shall be given to the protection and rout-
ment, except explosion protected equipment (according to ing of main cable runs for essential installations, for exam-
Sec.12) as specified for battery rooms may be installed. ple between machinery spaces and the navigation bridge
area, taking into account the fire risk existing in accommo-
c) Charging stations shall generally be mechanically venti- dation spaces.
lated with at least 30 changes of air per hour. An arrange-
ment as specified for battery rooms with battery capacity 403 Separation of main generators or main power convert-
in accordance with the actual battery capacity, but not less ers cabling
than 20 kVAh shall be used, see 304. For charging stations
in cargo holds having mechanical overpressure ventila- Cables for generators, transformers and converters required
tion, an alternative arrangement shall provide a natural according to Sec.2, shall be divided between two or more cable
ventilation outlet duct of sufficient capacity from the up- runs. These cable runs shall be routed as far away from each
per part of the charging station to free air. other as practicable and away from machinery having an in-
creased fire risk.
I 400 Cable routing
a) The cable routing shall be such that in case of a local fire
401 General in the engine room it should not be likely that two or more
such cable runs will be damaged. In areas where it is im-
a) Cable runs shall be installed well clear of substantial heat possible to separate the cable runs, they shall be protected
sources such as boilers, heated oil tanks, steam, exhaust or against direct exposure to fire (e.g. screens or ducts or fire
other heated pipes, unless it is ensured that the insulation protecting coating).
type and current rating is adapted to the actual tempera-
tures at such spaces. I 500 Lightning protection
b) Cables and wiring serving essential, important or emer- 501 General
gency installations shall be routed clear of galleys, ma-
chinery spaces and their casings and other high fire risk a) All vessels with masts or topmasts made of non-conduc-
areas, except for supplying equipment in those spaces. tive material shall be provided with lightning protection.
They shall not be run such that heating through fire divi- b) A lighting conductor shall be fitted on all non-metal masts
sions may jeopardise the function of the cable. Special at- on craft with a non-metal hull.
tention shall be given to the protection and routing of main
cable runs for essential installations, for example between c) Primary conductors provided for lightning discharge cur-
machinery spaces and the navigation bridge area, taking rents shall have a minimum cross section of 50 mm2 in
into account the fire risk existing in accommodation spac- copper or equivalent surge carrying capacity in alumini-
es. um.
c) For installations in connection with hazardous areas, re- d) The conductor shall be fastened to a copper spike of min-
quirements for selection of cables, cable routing and fix- imum diameter 13 mm reaching a minimum of 150 mm
ing, see Sec.11. above the mast. The conductor shall terminate to a copper
d) Other requirements for cable routing and installation are plate with a minimum area of 0.2 mm2 attached to the hull
located in Sec.10. and so located that it is immersed under all conditions of
heel.
e) The cable routing shall be such that in case of a local fire
in the engine room it is not likely that the cables to both du- e) Craft with a metal hull shall be fitted with a lightning con-
plicated consumers will be damaged. ductor on all non-metal masts. The conductor shall be as
required in c) and be terminated to the nearest point of the
f) In areas where it is impossible to separate the cable runs, metal hull.
they shall be protected against direct exposure to fire (e.g.
screens or ducts or fire-protecting coating).
g) Cables may exceptionally be routed through high fire risk
area, but shall then have additional fire protection, e.g. by J. Cable Selection
using cable tested in accordance with IEC 60331.
J 100 General
Guidance note: 101 General
Main cable runs are for example:
These technical requirements for cables and cable installations
— cable runs from generators and propulsion motors to main are considered relevant for the system design phase of a
and emergency switchboards project. However, they apply as well to the final installation on
— cable runs directly above or below main and emergency the vessel.
switchboards, centralised motor starter panels, section
boards and centralised control panels for propulsion and es- Other relevant requirements related to cables can be found
sential auxiliaries. elsewhere in the rules, especially:
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- — I401- requirements for the routing of electric cables

— Sec.9 - technical requirements for cables as electrical com-
402 Separation of cables for emergency services, essential ponents
and important equipment — Sec.10 - requirements for the installation of cables
DET NORSKE VERITAS

— Sec.11 - requirements for cables used in hazardous areas. The conductor cross-section of cables shall be sufficient to pre-
vent the insulation from being damaged by high temperatures
102 Fire resistant cables occurring by short circuits at the cable end.
When it is essential that a circuit shall function for some time Guidance note:
in a fire, and carrying the cable for such a circuit through an in-
creased fire risk area cannot be avoided (see Guidance note), The following maximum conductor temperatures by short cir-
cuits of 5 s maximum duration have been specified in IEC 60502-
then the cable shall be of a type capable of passing the test de- 2, "Extruded solid dielectric insulated power cables for rated
fined in IEC 60331-21 "Tests for electrical cables under fire voltages from 1 kV up to 30 kV":
conditions - circuit integrity", or adequately protected against
direct exposure to fire. 160°C for polyvinyl chloride insulation
Guidance note: 250°C for ethylene propylene rubber and cross-linked polyethyl-
ene insulation.
Machinery, machinery parts or equipment handling combustibles
are considered to present an increased fire risk. ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
302 PVC insulated conductors
103 Voltage rating
a) With reservations as specified in 201, PVC-insulated con-
a) The rated voltage of a cable shall not be less than the nom- ductors without further protection may be used for instal-
inal voltage of the circuits in which it is used. lation in closed piping system in accommodation spaces,
b) In systems with high-resistance earthed neutral, without when the system voltage is maximum 250 V. Such con-
automatic disconnection of circuits having insulation ductors may also be used for internal wiring of switch-
faults, and on every system with insulated neutral (IT-sys- boards and other enclosures and for control wiring
tems), the rated phase to earth voltage (U0) of the cables installed in closed piping system on machinery compo-
shall not be less than given in Table J1. nents. Other types of flame retardant switchboard wires
may be accepted for the same purpose. See Sec.9 D400.
Table J1 Rated voltage for high voltage cables b) Due to brittleness at low temperatures, cables with PVC
Highest system Rated voltage (U0) insulation and or main (inner) sheath, shall normally not
voltage (Um) (kV) be installed in refrigerated chambers, and holds for tem-
(kV) With automatic dis- Without automatic peratures below –20°C, or across expansion joints on
connection upon disconnection upon weather decks.
earth fault earth fault
7.2 3.6 6.0 303 Rubber insulated cables
12.0 6.0 8.7 Due to poor mechanical strength, the use of silicon-rubber-in-
17.5 8.7 12.0 sulated cables is limited to applications where a high tempera-
24.0 12.0 18.0 ture resistant cable is necessary (where the ambient
36.0 18.0 - temperature can be above 70°C).
J 200 Cable temperature J 400 Current rating

201 Cable temperature class 401 Earthing connections and conductors
The temperature class of power cables shall be at least 10°C
above the ambient temperature. However, 60°C power cables a) All earthing connections of copper shall have sufficient
are generally not permitted in engine and boiler rooms (for cross-section to prevent the current density exceeding 150
temperature classes, see Sec.9). A/mm² at the maximum earth fault currents that can pass
through them.
J 300 Choice of insulating materials b) Minimum cross-section of earthing conductors shall be as
301 Short circuit and cable listed in Table J2.
DET NORSKE VERITAS

Table J2 Earthing connections and conductors

Cross-section Q of
associated current
Arrangement of earth conductor carrying conductor Minimum cross-section of earth conductor
(One phase or pole)
(mm²)
1 i) Insulated earth conductor in cable for fixed installation. Q ≤ 16 Q
ii) Copper braid of cable for fixed installation. 16 < Q 1/2 of the current-carrying conductor, but not
less than 16 mm²
iii) Separate, insulated earth conductor for fixed installation
in pipes in dry accommodation spaces, when carried in the
same pipe as the supply cable.
iv) Separate, insulated earth conductor when installed inside
enclosures or behind covers or panels, including earth
conductor for hinged doors as specified in Sec.3 D401 d).
2 Uninsulated earth conductor in cable for fixed installation, be- Q ≤ 2.5 1 mm2
ing laid under the cable's lead sheath, armour or copper braid 2.5 < Q ≤ 6 1.5 mm2
and in metal-to-metal contact with this.
6<Q Not permitted
3 Separately installed earth conductor for fixed installation other Q < 2.5 Same as current-carrying conductor subject
than specified in 1 iii) and 1 iv). to minimum 1.5 mm² for stranded earthing
connection or 2.5 mm² for unstranded earth-
ing connection
2.5 < Q ≤ 120 1/2 of current-carrying conductor, but not less
than 4 mm²
120 < Q 70 mm2
4 Insulated earth conductor in flexible cable. Q ≤ 16 Same as current-carrying conductor
16 < Q 1/2 but minimum 16 mm2
Conductor current rating

1.12
The highest continuous load carried by a cable shall not exceed Df = ------------------
ts
the current rating specified in Tables J2 to J6, with considera- – ----
T
tion given to the correction factors given in 500. 1+e
J 500 Correction factors ts = the service time of the load currents in minutes
T = cable's time constant
501 Different temperature classes
= 0.245 d 1.35
If cables of different temperature classes are carried in the d = overall diameter of the cable in mm.
same bunch or pipe, the current ratings for all cables shall be
based on the lower temperature class. 506 Intermittent load
502 Multicore cables Cables used for loads that are not continuous, are repetitive and
For cables with more than 4 cores, the current rating are given have periods of no-load of less than 3 times the cable time con-
by the following equation: stant T (in minutes), the current rating may be increased by an
intermittent factor, If, calculated from:
JN = Jl / 3 N
tp
N = number of cores – -----
T
J1 = the current rating for a 1-core cable. 1–e
If = ------------------
ts
– ----
This applies by equal load on all cores. If some cores in such T
multi-core cables are not used, or are used for very small cur- 1–e
rents only, the current rating for the other cores may be in- ts = the service time of the load currents in minutes
creased after consideration in each case.
tp = the intermittent period in minutes (i.e. the total period be-
503 Ambient temperature fore of load and no-load before the cycle is repeated)
When the actual ambient air temperature clearly differs from ts, T and d, see 505.
45°C, the correction factors as given in Table J6 apply.
504 Bunching J 600 Parallel connection of cables
The current ratings specified in the Tables J3 to J5 are based on 601 General
maximum 6 cables, which can be expected to be under full load a) Parallel connection can be used for cables having conduc-
simultaneously being bunched together. If bunching of larger tor cross-section 10 mm² or above. All cables that are par-
formations is used for cables expected to be under full load si- allel connected shall be of the same length and cross-
multaneously, a correction factor of 0.85 shall be applied. section. The current-carrying capacity is the sum of all
505 Periodic load parallel conductors' current-carrying capacities.
For cables used for loads that are not continuous, i.e. operates b) A two, three or four-core cable, in which all cores are of
for periods of half or one hour and the periods of no-load is the same cross-section, can be used as single-core cable by
longer than 3 times the cable time constant T (in minutes), the parallel connection of all cores in each end. The current-
current rating may be increased by a duty factor, Df, calculated carrying capacity of such single-core cable is the sum of
from: the cores' current-carrying capacities.
DET NORSKE VERITAS

c) With parallel connection of multi-core cables, one core of 802 Rating of cables with temperature class 85°C is given in
each cable shall be used for each phase and neutral con- Table J4.
nection, respectively.
Table J4 Rating of cables with temperature class 85°C
d) With many parallel-connected cables, the current distribu- Nominal Current rating (A)
tion may be uneven. However, no single cable shall, after cross-sec- (Based on ambient temperature 45°C)
installation, carry more than its capacity. This shall be tion (mm2) Single-core 2-core 3 or 4-core
demonstrated at full load of the consumer.
1 16 14 11
1.5 20 17 14
J 700 Additional requirements for A.C. installations, 2.5 28 24 20
and special D.C. installations 4 38 32 27
701 General 6 48 41 34
10 67 57 47
a) Generally, multi-core cables shall be used on A.C. instal- 16 90 77 63
lations. 25 120 102 84
35 145 123 102
b) On three-phase, four-wire circuits, the cross-section of the 50 180 153 126
neutral conductor shall be the same as for a phase conduc- 70 225 191 158
tor up to 16 mm2, and at least 50% of that of a phase con- 95 275 234 193
ductor for larger cross-sections, though not larger than 50 120 320 272 224
mm2. The braiding in a cable is not accepted used as the 150 365 310 256
neutral conductor. 185 415 353 291
240 490 417 343
702 Single-core cables 300 560 476 392
D.C. A.C. D.C. A.C. D.C. A.C.
a) Single-core cables are not to have steel-wire braid or ar- 400 650 630 553 536 445 441
mour. 500 740 680 629 578 518 476
630 840 740 714 629 588 518
b) Single-core cables for the same circuit shall be laid closely
together, except for the ventilation spaces when such are 803 Rating of cables with temperature class 95°C is given in
necessary (see 504) and shall be laid under the same clips Table J5.
or in the same pipe, so that the bunch is not divided by any
magnetic material. Cable penetrations and glands for sin- Table J5 Rating of cables with temperature class 95°C
gle-core cables shall be of non-magnetic material. If two Nominal Current rating (A)
or more parallel-connected cables per phase are used, the cross-sec- (Based on ambient temperature 45°C)
2
tion (mm )
distribution of the different phases shall be such that the Single-core 2-core 3 or 4-core
current distribution becomes as equal as possible. 1 20 17 14
1.5 24 20 17
c) For D.C.-installations with a high "ripple" content (e.g. 2.5 32 27 22
thyristor (SCR) units), a) and b) are applicable. 4 42 36 29
6 55 47 39
J 800 Rating of cables 10 75 64 53
801 Rating of cables with temperature class 60°C is given in 16 100 85 70
25 135 115 95
Table J3. 35 165 140 116
50 200 175 140
Table J3 Rating of cables with temperature class 60°C 70 255 217 179
Nominal Current rating 95 310 264 217
cross-sec- (Based on ambient temperature 45°C) 120 360 306 252
2
tion (mm ) Single-core 2-core 3 or 4-core 150 410 349 287
A A A 185 470 400 329
1 8 7 6 240 570 485 400
1.5 12 10 8 300 660 560 460
2.5 17 14 12
4 22 19 15 804 Correction factors for ambient temperature are given in
6 29 25 20 Table J6.
10 40 34 28
16 54 46 38
25 71 60 50
35 87 74 61
50 105 89 74
70 135 115 95
95 165 140 116
120 190 162 133
150 220 187 154
185 250 213 175
240 290 247 203
300 335 285 235
D.C. A.C. D.C. A.C. D.C. A.C.
400 390 380 332 323 273 266
500 450 430 383 365 315 301
630 520 470 442 400 364 329
DET NORSKE VERITAS

Table J6 Correction factors for ambient temperature

Cable temperature Ambient temperature (°C)
class
°C 35 1) 40 45 50 55 60 65 70 75 80 85
60 2) 1.29 1.15 1.00 0.82 - - - - - - -
75 1.15 1.08 1.00 0.91 0.82 0.71 0.58 - - - -
85 1.12 1.06 1.00 0.94 0.87 0.79 0.71 0.61 0.50 - -
95 1.10 1.05 1.00 0.95 0.89 0.84 0.77 0.71 0.63 0.55 0.45
1) Correction factors for ambient temperature below 40°C will normally only be accepted for:
— cables in refrigerated chambers and holds, for circuits which only are used in refrigerated service
— cables on vessel with class notation restricting the service to non-tropical water.
2) 60°C cables shall not be used in engine and boiler rooms.
DET NORSKE VERITAS

SECTION 3
EQUIPMENT IN GENERAL
A. General Requirements — inclination 22.5° from normal level in any direction

under normal dynamic conditions
A 100 References — inclination 25° from normal level in any direction for
101 General emergency installations.
Guidance note:
a) This section contains technical requirements for all electri-
cal equipment in general. Additional requirements for spe- Other values may be accepted if justified by calculations for the
particular vessel or offshore unit.
cial types of equipment can be found in Sec.4 to Sec.9.
National authorities may require larger inclinations.
b) Requirements for electrical systems as a whole can be
found in Sec.2. Requirements for installation of equipment ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
can be found in Sec.10.
B 200 Vibrations and accelerations
102 Compliance with standards
201 General
The requirements in this section are based on the IEC standard
system in general. a) Electrical equipment and components shall be constructed
Guidance note: to withstand, without malfunctioning, or electrical con-
nections loosening, at least the following values:
IEC Standards covering the general requirements for electrical
components for ships are: IEC 60092-101 ”Definitions and gen- — vibration frequency range 5 to 50 Hz with vibration
eral requirements”, and parts of IEC 60092-201 “Systems design
- General”. velocity amplitude 20 mm/s
— peak accelerations ±0.6 g for vessels of length exceed-
For offshore units: IEC 61892, part 1, ”General requirements and ing 90 m (duration 5 to 10 s)
conditions”, part 2 “Systems design”, and part 3 “Equipment”, — peak accelerations ±1 g for MOUs and vessels of
apply.
length less than 90 m (duration 5 to 10 s).
b) For flexible mounted equipment, special considerations
shall be given to the construction of the equipment since
larger vibrations may occur.
B. Environmental Requirements B 300 Temperature and humidity
B 100 Inclinations 301 Ambient temperatures
101 General a) Electrical equipment including components inside enclo-
sures in switchboards etc., shall be constructed for contin-
a) Electrical equipment and components on ships and HS, uous operation at rated load, at least within the ambient air
LC and NSC shall be designed to operate satisfactorily un- temperature ranges listed in Table B1 and cooling water
der the following inclinations of the vessel: temperatures in 302.
— static conditions: list 15º, trim 5° b) Modifications of the equipment may be required if the ac-
— dynamic conditions: rolling ±22.5º, pitch ±7.5º (may tual ambient air temperatures will clearly exceed the limits
occur simultaneously) in a).
b) Emergency installations on ships and HS, LC and NSC, c) If some equipment has a critical maximum ambient tem-
except as stated in c), shall be designed to operate satisfac- perature by which it suddenly fails, this critical tempera-
torily under the following inclinations of the vessel: ture should not be less than 15°C above the limits specified
in the table.
— static conditions: list 22.5°, trim 10°. d) For vessels with class notation restricting the service to
non-tropical waters, the upper ambient air temperature
c) On ships for the carriage of liquefied gases and chemicals, limits according to Table B1 may be reduced by 10°C.
the emergency power supply is to remain operational with
the ship flooded up to a maximum final athwart ship incli- e) For electronic and instrumentation devices the require-
nation of 30º, when the deck is not immersed. ments in DNV-OS-D202 applies.
d) For mobile offshore units the inclination values are as fol- Guidance note:
lows: These rules do not appraise ambient conditions for transport or
storage of electrical equipment.
— inclination 15° from normal level in any direction un-
der normal static conditions ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
DET NORSKE VERITAS

Table B1 Ambient air temperature ranges

Minimum ambient air temperature
Location range for continuous operation (°C)
From To
1 Engine rooms, boiler rooms, galleys and similar spaces, accommodation spaces. 0 +45
2 Open deck, dry cargo holds, steering gear compartments, deckhouses, forecastle –25 +45
spaces and similar spaces which are not provided with space heating.
3 a) Refrigerated chambers and holds, general. The minimum +45
b) Refrigerated chambers and holds, for equipment which only is used in refrigerated temperature specified for +35
service. the installation, but not
above –20
302 Cooling water temperatures a) The temperature rise of enclosures and their different parts
shall not be so high that fire risk, damage to the equipment,
Electrical equipment shall be constructed for continuous oper- adjacent materials or danger to personnel occurs.
ation under full rated load, at a seawater temperature range
from 0 to +32°C. Electrical equipment on vessels with class b) Normally, the temperature rise of enclosures for other
notation restricting the service to non-tropical waters shall be equipment should not exceed 50°C, or 40°C for enclosures
constructed for continuous operation at a seawater temperature that are installed in contact with flammable materials such
range from 0 to +25°C. as wooden bulkheads. Exemptions may be considered for
303 Humidity equipment that is especially protected against touching or
splashing of oil.
Electrical equipment shall be constructed to withstand, and
function safely in relative humidity up to 95%. c) For luminaries, resistors and heating equipment, see Sec.8.
C. Equipment Ratings D. Mechanical and Electrical Properties

C 100 Electrical parameters D 100 Mechanical strength
101 General 101 General
Equipment shall have sufficient mechanical strength to with-
a) Unless otherwise clearly stated by the purchaser, equip-
ment shall be rated for continuous duty. (Duty type S1). stand the strains they are likely to be exposed to when installed.
b) All conductors, switchgear and accessories shall be of 102 Enclosures

such size as to be capable of carrying, without their respec-
tive ratings being exceeded, the current which can normal- a) Enclosures shall be resistant to weather, oil and chemicals
ly flow through them. They shall be capable of carrying and have sufficient mechanical strength when intended to
anticipated overloads and transient currents, for example be installed in an area where risk of mechanical damage
the starting currents of motors, without damage or reach- exists.
ing abnormal temperatures. b) Metallic enclosures installed on deck or in compartments
where severe corrosion problems can be expected shall be
102 Voltage and frequency made of especially corrosion resistant material or dimen-
sioned with a certain corrosion allowance.
a) Equipment connected to the system shall be constructed
for the frequency and voltage tolerances described in c) Light metal alloys as i.e. aluminium shall be avoided as
Sec.2. A200. enclosure materials if not documented to be seawater re-
sistant and installed so that local corrosion caused by con-
b) With respect to fast voltage transients, equipment connect- tact does not occur.
ed to the system shall be capable of withstanding fast tran-
sients with peak voltage amplitude of 5.5 times UN, and d) Enclosures that are so placed that they are likely to be
rise time or delay time of 1.2µs / 50µs. stepped or climbed on, shall be able to withstand the
weight of a man. This applies for example to most electri-
103 Harmonic distortion cal machines in the engine room, winch motors on deck,
All equipment shall be designed to operate at any load up to the etc. A test to this effect, with a force of 1000 N applied by
rated load, with a supply voltage containing the following har- a flat surface 70 x 70 mm, may be carried out as type test
monic distortion: or random test.
e) Enclosures shall withstand the ambient air temperatures
— total harmonic content not exceeding 5% of voltage root which are specified in B, with the equipment at full load.
mean square value The temperature rise of enclosures shall not be so high that
— no single harmonic being greater than 3% of voltage root fire risk, damage to adjacent materials or danger to person-
mean square value. nel occurs.
104 Electromagnetic compatibility (EMC) f) When enclosures of other materials than metal are used,
they should at least withstand immersion in water at 80°C
Equipment producing transient voltage, frequency and current for 15 minutes, without showing signs of deterioration,
variations is not to cause the malfunction of other equipment and the material shall be flame retardant according to IEC
on board, neither by conduction, induction or radiation. 60092-101. A test to this effect may be carried out as type
C 200 Maximum operating temperatures test or random test. This also applies to screens of lumi-
naires, and to windows in other enclosures, if made of oth-
201 General er material than glass.
DET NORSKE VERITAS

103 Materials 203 Anti condensation

a) Electrical equipment shall be constructed of durable non- a) For equipment where condensation is likely, for example
hygroscopic materials which are not subject to deteriora- those that are idle for long periods, heating arrangements
tion in the atmosphere to which it is likely to be exposed. may be required.
b) Electrical equipment shall be constructed of at least flame b) All high voltage converters, transformers and rotating
retardant materials. equipment not located in heated and ventilated spaces,
shall be provided with heating elements in order to prevent
Guidance note: condensation and accumulation of moisture. The heating
Even in "dry" locations, up to 96% relative humidity with a salt shall be automatically switched on at stand still.
content of 1 mg salt per 1 m³ of air may occur; in machinery spac- c) All equipment equipped with air/water heat exchangers
es also mist and droplets of fuel- and lubricating oil.
shall be provided with heating elements in order to prevent
Tests for flame retardant properties are described in IEC 60092- condensation and accumulation of moisture. The heating
101 shall be automatically switched on at stand still.
D 300 Termination and cable entrances
104 Material detoriation due to cargo vapours 301 Termination
Where the cargo gases or vapours are liable to damage the ma-
terials used in the construction of electrical apparatus, careful a) All equipment shall be provided with suitable, fixed termi-
consideration shall be given to the characteristics of the mate- nals in an accessible position with sufficient space for con-
rials selected for conductors, insulation, metal parts, etc. As far nection of the external incoming cable or wiring.
as is practicable, components of copper and aluminium, shall b) All connections for current-carrying parts and earthing
be encapsulated to prevent contact with gases or vapours. connections shall be fixed so that they cannot loosen by vi-
Guidance note:
bration. This also applies to fixing of mechanical parts
when found necessary.
Attention is drawn to the possibility of gases and vapours being
transferred from one point to another through cables or cable c) Terminals for circuits with different system voltages shall
ducting unless appropriate precautions are taken, for example, be separated, and clearly marked with the system voltage.
adequate end sealing.
d) High voltage terminals, above 1000 V, shall not be located
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- in the same box, or part of enclosure, as low voltage termi-
nals.
D 200 Cooling and anti-condensation e) Electrical equipment that needs to be connected to protec-
201 General tive earth according to 400 shall be provided with suitable
fixed terminal for connecting a protective earth conductor.
a) Where electrical equipment depends upon external cool- The terminal shall be identified by a symbol or legend for
ing, the following shall be complied with: protective earthing (PE).
— an alarm shall be initiated when auxiliary cooling or 302 Cable entrance

ventilation motors stop running. Alternatively a flow a) Cable entrances into enclosures shall be from below or
monitoring alarm shall be initiated from the side (except for enclosure IP 20), in order to pre-
— the windings in the cooled equipment for essential vent ingress of water or other liquids.
services shall be equipped with temperature detectors
for indication and alarm of winding temperature b) Cable entries from the top is accepted provided that the ca-
— the windings in the cooled equipment for important ble entrance is provided with glands or MCTs preventing
services shall be equipped with temperature detectors water to enter the equipment.
for alarm at high winding temperature. c) Cable entrances shall be fit for the outer diameter of the ca-
ble in question.
b) Where the cooling of electrical equipment depends upon
general room ventilation only, temperature detectors in the D 400 Equipment protective earthing
equipment are not required.
401 General
Guidance note:
a) Exposed metal parts of electrical machines or equipment
These requirements will not be enforced when technically infea- that are not intended to be live but, which are liable, under
sible as for example for thyristors. fault conditions to become live, shall be earthed. Fixing
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- devices between a high voltage enclosure and steel hull
parts are not to be relied upon as the sole earthing connec-
202 Water cooled heat exchangers tion of the enclosure.
a) Where cooling of equipment is arranged through air-water b) In switchgear and controlgear a good reliable earth con-
heat exchangers, these shall be arranged to prevent entry nection of all metallic non-current carrying parts shall be
of water into the equipment, whether by leakage or con- insured. In main and emergency switchboards a continu-
densation. Leakage alarm shall be provided. ous earth-bar is required.
b) Heat exchangers in high voltage equipment shall be of c) For the interconnections within an enclosure, for example
double tube type and shall be fitted with leakage alarm. between the frame, covers, partitions or other structural
parts of an assembly, the fastening, such as bolting or
c) The construction and certification of the air-water heat ex- welding is acceptable, provided that a satisfactory conduc-
changers shall comply with the requirements for pressure tive connection is obtained.
vessels, see the Rules for Classification of Ships, Pt.4 d) Compartment doors can be earthed through their metallic
Ch.7. hinges when they do not carry any electric components. If
d) For direct water cooling of semi-conductor equipment, see the doors do carry components such as switches, instru-
Sec.7. ments, signal lamps, etc. with voltage exceeding 50 V
DET NORSKE VERITAS

A.C. or 50 V D.C., the doors shall be connected to the Guidance note:

switchboard or enclosure by a separate, flexible copper Equipment located in machinery spaces may be considered as be-
earth conductor. In high voltage equipment, this conductor ing accessible to qualified personnel only. The same applies to
shall have at least 4 mm² cross-section. equipment located in other compartments that normally are kept
locked, under the responsibility of the ship's officers.
e) Each high voltage assembly shall be earthed by means of
earth conductors. Each assembly shall be provided with a ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
main earthing conductor of cross-section at least 30 mm²
copper, with at least 2 adequate terminals for connection D 600 Clearance and creepage distances
to the steel hull. Each unit enclosure and other metallic 601 General
parts intended to be earthed shall be connected to this main
earthing conductor or bar. The distance between live parts of different potential and be-
tween live parts and the cases of other earthed metal, whether
f) Earthed metallic parts of withdrawable components in across surfaces or in air, shall be adequate for the working volt-
high voltage equipment shall remain earthed, by means of age, having regard to the nature of the insulating material and
a special earth device, until they have been fully with- the conditions of service.
drawn. The earthing shall be effective also when in test po-
sition with auxiliary circuits live. 602 Clearance and creepage distances for low voltage
equipment
g) The secondary winding of any current or voltage trans-
former installed in a high voltage system shall be earthed The minimum clearance and creepage distances for bare bus
by a copper conductor of at least 4 mm2 cross-section. Al- bars in low voltage equipment are given in Table D1, and shall
ternatively, unearthed secondary winding with overvolt- be complied with when insulating materials with tracking in-
age protection is accepted. dex 175 V are used. For type tested assemblies and partially
type tested assemblies the distances given in Sec.4 A110 may
Exception: apply.
Exception from this requirement is given for machines or
equipment: Table D1 Low voltage equipment clearances or creepage
between phases (including neutral) and between phases and
— supplied at a voltage not exceeding 50 V D.C. or A.C. be- earth
tween conductors Rated insulation volt- Minimum clear- Minimum creepage
— supplied at a voltage not exceeding 250 V by safety isolat- age, A.C. root mean ances (mm) distances (mm)
ing transformers supplying only one consuming device. square or D.C. (V)
Auto-transformers may not be used for the purpose of Up to 250 V 15 20
achieving this voltage From 250 to 690 V 20 25
— constructed in accordance with the principle of double in-
sulation. Above 690 V 25 35
(Maximum 1000 V)
D 500 Enclosures ingress protection 603 Clearance and creepage distances for high voltage
501 General equipment
a) All equipment shall be constructed to prevent accidental a) Minimum clearance distances in high voltage equipment
touching of live parts, and shall have enclosures with a are given in Table D2.
minimum degree of protection dependent upon the instal- b) Minimum creepage distances for main switchboards and
lation area, according to the installation requirements in generators are given in Table D3, and for other equipment
Sec.10 Table B1, unless a higher degree is required by in D4.
these rules.
c) All insulating materials for fixing and carrying live parts
b) For equipment supplied at nominal voltages above 500 V shall have tracking index of at least 300 V according to
up to and including 1000 V, and which is accessible to IEC 60112.
non-qualified personnel, it is in addition required that the
degree of protection against touching live parts shall be at
Table D2 Clearances for high voltage equipment in systems
least IP 4X.
with insulated neutral between phases (including neutral) and
c) High voltage switchgear and controlgear assemblies shall between phases and earth
have enclosure type of at least IP 32. Nominal voltage of the system, Minimum clearance distance for
d) High voltage transformers shall have enclosure type of at (V) 1) (mm)
least IP 23, when located in spaces accessible only to qual- Main switch- Other equip-
ified personnel, and at least IP 54 in other locations. boards and gen- ment
erators
e) High voltage rotating electrical machines shall have a de-
gree of protection by enclosure of at least IP 23, unless a 1000 - 1100 25 25
higher degree is required by location. Connection boxes of 3000 - 3300 55 55
high voltage rotating machines shall in all cases have a de- 6000 - 6600 90 90
gree of protection of at least IP 44. 10000 - 11000 120 120
f) A separate locked room with warning signs, and without Above 11000 – maximum 15000 160 160
other installations, can be regarded as an enclosure by it- 1) Intermediate values with corresponding distances are accepted.
self, that is, no requirement for equipment protection ap-
plies.
DET NORSKE VERITAS

b) The switchgear and fuse gear for each circuit shall be

Table D3 Minimum creepage distances for high voltage main marked with circuit designation, cable cross-section and
switchboards and generators rating of fuses or necessary data for easy recognition of
components and circuits according to relevant drawings.
Nominal voltage Minimum creepage distance for proof (tracking
of the system, index 300) (mm) c) If the switchboard contains two or more distribution sys-
(V) 1) tems with different voltages, the different parts shall be
300 V 375 V 500 V > 600 V marked with the respective voltages at the partitions.
1000 - 1100 26 2) 24 2) 22 2) 20 2) d) Terminals for circuits with different system voltages shall
3000 - 3300 63 59 53 48 be clearly separated, and clearly marked with the voltage.
6000 - 6600 113 108 99 90 e) All terminals for connection of external instrumentation
10000 - 11000 183 175 162 150 and control cables, as well as the conductor ends of these
1) Intermediate values with corresponding distances are accepted. cables shall be marked for identification, preferably in ac-
2) Minimum 35 mm is required for bus bars and other bare conductors in cordance with the designation used in the wiring diagram
main switchboards. or schematics or loop diagrams. See also Sec.4 A100.
Table D4 Minimum creepage distances for other high voltage 104 Signboards and warnings
equipment
a) Each switchgear fed from more than one individually pro-
Nominal voltage Minimum creepage distance for proof (tracking
of the index 300) (mm) tected circuit shall be marked with a warning sign stating
system, that these circuits shall be isolated when the main circuit is
1) 300 V 375 V 500 V > 600 V isolated for maintenance purpose. A warning sign is not
(V)
1000 - 1100 18 17 15 14 required if all live circuits within the enclosure are discon-
nected together with the main power circuit.
3000 - 3300 42 41 38 36
6000 - 6600 83 80 75 70 b) When, for fuses above 500 V, the fuseholders permit the
insertion of fuses for lower nominal voltage, special warn-
10000 - 11000 146 140 130 120 ing labels shall be placed, for example "Caution, 660 V
1) Intermediate values with corresponding distances are accepted. fuses only".
c) Special "high voltage" warning signboards are required on
all high voltage machines, transformers, cables, switch-
E. Marking and Signboards and controlgear assemblies.
E 100 General
101 General
F. Insulation
a) All equipment shall be externally marked to enable identi-
fication in accordance with the documentation of the pow- F 100 Insulation materials
er distribution system, and be marked with the 101 General
manufacturer's name. In addition the system voltage shall
be indicated on switchgear and assemblies. a) Insulating materials, general purpose type, for supporting
conductors (not defined as for machines and cables) shall
b) All equipment shall if necessary be marked to ensure cor- withstand the temperatures to which they are likely to be
rect use. exposed. This is normally ambient temperature plus the
c) See Sec.11 for the requirements for the marking of hazard- heat from the conductor itself during full load.
ous area equipment. b) A thermal classification in accordance with IEC 60085
d) All marking shall be made by flame retardant, non-corro- shall be assigned to the insulation system when used in
sive materials and be permanently fixed. machines. The normally used classes are shown in Table
F1, with the maximum exposure temperatures (including
e) Labels bearing clear and indelible indications shall be so ambient) shown in the right column.
placed that all components and all equipment can be easily
identified. c) Insulating materials shall be at least flame retardant.
d) Insulating materials shall be tracking resistant in accord-
102 Rating plate ance with IEC 60112. A tracking index of at least 175 V
All equipment shall be fitted with a rating plate giving infor- will be required for low voltage equipment. For high volt-
mation on make, type, current, voltage and power rating and age equipment the tracking index shall be minimum 300
other necessary data for the application. V. See Guidance note below, and Sec.13 (definitions) re-
garding Tracking index.
Guidance note:
More detailed requirements for information that shall be noted on Table F1 General insulation classes
rating plates may be found in other applicable sections regarding
each equipment type contained in this chapter (Sec.4 to Sec.9). Insulation class Maximum temperature
(thermal class) (°C)
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- A 105
B 130
103 Labels for switchgear, terminals etc.
F 155
a) Internal components in equipment and assemblies as H 180
switchgear, controlgear, fuse gear, socket outlets, lighting 220 220
equipment and heating equipment shall be marked with
make, type, current, voltage and power rating and other Guidance note:
necessary data for the application (i.e. to which standard Insulation classes shall be classified according to IEC 60085,
the equipment is produced). "Recommendations for the classification of materials for the in-
DET NORSKE VERITAS

sulation of electrical machinery and apparatus in relation to their Tests according to similar national standards may be considered.
thermal stability in service". ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
Tracking index (the materials ability to withstand creep current)
shall be determined according to IEC 60112, "Recommended 102 Cable insulation
method for determining the comparative tracking index of solid For requirements regarding the insulation of electrical cables,
insulating materials under moist conditions". see Sec.9.
DET NORSKE VERITAS

SECTION 4
SWITCHGEAR AND CONTROLGEAR ASSEMBLIES
A. Construction Guidance note:

Switchgear and assemblies constructed of other materials may be
A 100 General accepted provided requirements in Sec.3 are complied with.
101 Applicable standards ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
Switchgear and controlgear assemblies shall generally comply 106 Circuit separation
with IEC 60439 and IEC 60092-302 for low voltage equip-
ment, and IEC 60298 and IEC 6092-508 for high voltage a) There is to be arranged a separate cubicle for each genera-
equipment. In case of gas insulated, enclosed high voltage sys- tor, with flame retardant partitions between the different
tems, IEC 60466 apply. generator cubicles and between these and other cubicles.
The partitions shall withstand the effect of an internal arc,
102 General and prohibit this from spreading to other cubicles.
All switchboards and assemblies shall be safe against acciden- b) Controlgear for essential or important consumers is to be
tal touching of live conductors during normal operation of the separated from each other, and from other current carrying
switchboard or assemblies. parts, by flame retardant partitions providing protection of
the cubicle in case of an arcing fault occurring in the
103 Internal arc withstand neighbouring cubicle.
a) All switchboards and assemblies shall be safe for opera- The arrangement shall be so that maintenance work can be
tors in front of, or at the rear, against effects of internal carried out in each unit without danger when isolated.
arcs occurring inside the enclosure. For high voltage as- c) Controlgear for non-important consumers may be in-
semblies, see B301. stalled in a common cubicle provided this cubicle could be
effectively isolated.
b) A switchboard or assembly shall be designed to withstand
the short circuit forces for minimum 1 s, created by the d) Consumer controlgear installed in main switchboards are
short circuit current and magnitude at the particular point to be placed in cubicles separated from all other parts of
of the system without endangering the integrity of the out- the switchboard by partitions of flame retardant material.
er switchboard enclosure. e) Equipment for different distribution systems are to be
placed in separate switchboards (panels), or are to be sep-
104 Accessibility arated from each other by partitions clearly marked with
the actual voltages and system identifications.
a) Instruments, handles, push buttons or other devices that
should be accessible for normal operation are to be located f) Switchgear and controlgear assemblies supplied by differ-
on the front of switchboards and controlgear. ent supply circuits shall not be placed in the same enclo-
sure.
b) All other parts that might require operation are to be acces- g) For separation due to system redundancy, see Sec.2.
sible. If placed behind doors, the interior front is to comply
with enclosure type IP 20. When located in spaces acces- 107 Handrails
sible to non-qualified personnel, fuses with accessible cur-
rent-carrying parts may be permitted, if the door is Main and emergency switchboards and other switchboards re-
lockable. Operation in this context means for example requiring operation shall have handrails of insulating materials.
set of protective devices and replacement of control circuit 108 Nameplates and marking
fuses inside the assembly.
See Sec.3 E for general requirements regarding marking of
c) Doors, behind which equipment requiring operation is equipment. In addition, the following apply in front of switch-
placed, are to be hinged. gear and controlgear assemblies, for each circuit.
d) Hinged doors, which are to be opened for operation of a) The rating (voltage, current and fault current capabilities)
equipment, are to be provided with easily operated handles of the protective devices for each circuit shall be perma-
or similar. There is also to be arrangements for keeping the nently indicated at the location of the protective device.
doors in open position.
b) All protection devices with adjustable settings are to have
e) All sections of switchboards and controlgear that require means that readily identify the actual setting at the location
maintenance are to be accessible for maintenance work. of the protective device.
c) Circuit designation for outgoing circuits and from where,
Guidance note:
on incoming feeders.
Normally, all connections of conductors, bus bar joints and me-
chanical fastening of components and bus bars shall be accessi- d) Switchboards provided with more than one supply circuit
ble for maintenance. are to be marked with a warning that both or all supply cir-
cuits are to be disconnected before any maintenance work
If the construction does not allow periodical maintenance, the as- is carried out. Alternatively, a listing of all supply circuits
sembly may be designed for maintenance free operation during a
20-year service life. shall be located inside the switchboard.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 109 Ingress protection

Switchboards shall be of "dead front" type and have enclosure
105 Materials protection according to Sec.10 Table B1.
Framework, panels and doors are normally to be of steel or alu- 110 "Type tested assemblies" and "Partly type tested assem-
minium alloy, and are to be of rigid construction. blies"
DET NORSKE VERITAS

a) Electrical low voltage assemblies constructed and tested in 104 Fuses

accordance with IEC 60092-302, item 7.1.2.101 (referring
to IEC 60439-1) are accepted as long as the following con- Fuses shall normally comply with one of the following stand-
ditions are met: ards:
— minimum clearance distance shall be 8 mm, minimum — IEC 60269 for low voltage fuses
creepage distance shall be 16 mm — IEC 60282-1 for high voltage fuses.
— the assembly has been type tested with impulse volt-
age test in accordance with IEC 60439-1 105 Circuit breakers, on-load switches, disconnectors, and
— maximum operating temperature of bus bars shall be contactors
documented to be acceptable with respect to fixing
materials and internal temperature by a full current a) Switchgear and controlgear shall comply with:
type test
— maximum temperature rise at termination points for — IEC 60947 for low voltage equipment
external cables shall be 60ºC — IEC 60056, IEC 60470, IEC 60129 for high voltage
— such assemblies shall not be installed in machinery equipment.
space category "A" (see Sec.2 I103).
b) All fault switching and protecting components such as cir-
b) For bus bar trunking systems where the conductors are cuit breakers and fuses are to have a fault current with-
fixed for the whole length with an insulating rail or simi- stand and interruption capacity of not less than the
lar, distances in accordance with IEC 60947-4-1 Part 4 maximum short circuit current available at the relevant
(Contactors and motor starters - Section 1), may be accept- point of their installation.
ed. c) All load switches and contactors are to have a rating not
less than the maximum load current at their point of instal-
lation. Particularly, contactors shall be protected against
the possibility of the contactor breaking current exceeding
B. Power Circuits their load break capacity in fault situations.
B 100 Power components in assemblies d) Fuse switches using the fuse link contacts as making and
101 Main bus bar sectioning breaking contacts are not accepted where switches are re-
quired according to Sec.3, but may be used as isolating
See Sec.2 for requirements regarding main bus bar division ar- switch.
rangement.
e) The construction is to be such that accidental making or
102 Bus bar materials breaking, caused by the vessel's inclination, movements,
vibrations and shocks, cannot occur.
a) Bus bars and other conductors shall normally be made of
copper or copper covered aluminium. f) Undervoltage and closing coils, including contactor coils,
b) Copper coated aluminium or pure aluminium bus bar shall are to allow closing of the switchgear and controlgear
be adequately protected against corrosion by placing in an when the voltage and frequency are 85 to 110% of the rat-
air conditioned environment, by special coating sealing of ed values, and are not to cause release at voltage and fre-
the aluminium or by the aluminium itself being seawater quency above 65% of the rated values.
resistant.
106 Switch-gear
103 Rating of bus bars
a) Each outgoing circuit on a main switchboard or a distribu-
a) The shape, configuration and cross-section are to be such tion switchboard is to be provided with an accessible
that the temperature rise will not exceed 45°C at rated switch on the switchboard front for isolating purposes.
load. One of the following solutions shall apply:
b) Bus bars and other conductors with their supports are to be — a multipole circuit breaker
so mechanically or thermally dimensioned and fixed that — a multipole fused circuit breaker
they can withstand for 1 s the forces occurring by the max-
imum short circuit current which can occur without detri- — a multipole load switch and fuses.
mental effect.
b) The arrangement is to be such that any fuses can be re-
c) The cross-section of bus bars for neutral connection on an placed without risk of touching live parts.
A.C. three-phase, four-wire system, and for equaliser con-
nection on a D.C. system, is to be at least 50% of the cross- c) When multipole switch and fuses are used and the switch
section for the corresponding phases (poles). is installed between the bus bars and the fuses, the follow-
ing apply:
d) For maximum temperatures of bus bars in type tested and
partially type tested assemblies the requirement in A110 — the switch is to have a breaking capacity of at least 6
applies. times its full-load current
Guidance note:
— the making capacity of the switch is to be so adapted
in relation to the fuses’ rupture characteristic that no
Reference is made to IEC 60439 for current carrying capacity of damage to the switch occurs even when it is closed on
bus bars.
a short circuit.
The general equation of current ratings at different temperature
rises is: d) On a distribution board the multipole switch may be omit-
ted when maximum 63 A fuses are used.
I1 ∆ ϑ1
---- = ---------- Guidance note:
I2 ∆ ϑ2 For high voltage equipment switching off by an auxiliary circuit
will be accepted provided that the off–control switch is placed in
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- front of the relevant compartment and a manual off-switching
DET NORSKE VERITAS

means is provided at the circuit breaker when front door is — the enclosure for the battery section shall have ade-
opened. quate strength so that an exploding battery does not
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- damage other parts of the assembly.
107 Disconnection and isolation for safety purposes c) See Sec.2 I300 for requirements regarding the location and
ventilation of battery installations.
Means are to be provided for the isolation of the supply to each
controlgear and distribution board. The following alternative B 300 Additional requirements for high voltage assem-
arrangements may be used: blies
— a multipole isolating switch at the controlgear 301 General design and construction
— the circuit switchgear on the switchboard from which the a) High voltage switchgear and controlgear assemblies are to
controlgear or distribution board is supplied. The switch- be metal-clad in accordance with IEC 60298, or of a con-
gear used for this purpose is to be lockable in the "off" po- struction giving equivalent safety with respect to person-
sition, if remote from the consumer or its controlgear nel safety and system integrity. The switchgear shall able
— the circuit fuses on the switchboard from which the con- to withstand an internal short circuit arcing failure with the
trolgear or distribution board is supplied. For non-impor- maximum duration and magnitude, which can occur on the
tant consumers supplied by a distribution switchboard, it is particular point of the installation without harmful effect
accepted that the switchgear or fuses for the supply circuit to operators.
to this switchboard are used as common isolating device.
The switchgear used for this purpose is to be lockable in b) The switchgear or switchboard shall be type tested to dem-
the "off" position onstrate that it will withstand the effects of an internal arc
— the disconnection device for high voltage switchgear failure (e.g. testing in accordance with Appendix AA of
(above 1000 V) shall have visible indication of contact po- IEC 60298).
sitions. c) There shall be separate compartments with IP rating to at
least IP 20 towards other compartments in the cubicle for
108 Safety earthing of high voltage circuits at least the following components:
Each circuit is to be fitted with an integral means of earthing
— control and auxiliary devices
and short circuiting for maintenance purposes, or alternatively
an adequate number of portable earthing and short circuiting — each main switching device
devices, suitable for use on the equipment in question, is to be — components connected to one side of the main switch-
kept on board. ing device (the outgoing circuit)
— components connected to the other side of the main
109 Short circuit proof internal wiring switching device (the bus bars).
Connections without sufficient short circuit protection for the
d) Normally, partitions between the compartments shall be
conductor sizing are to be installed short circuit proof (defined made of metal. Alternatively, a partition of other materials
in Sec.13). not intended to be earthed is accepted, provided it is veri-
Guidance note: fied that the safety is of at least the same standard.
This requirement applies to branching of for control power and e) Means are to be provided for the disconnection and isola-
measuring signals from bus bars and generator terminals, to con-
ductors between batteries and short circuit protection, and to con- tion of all circuit breakers and fused circuit breakers, either
ductors between separated bus bar sections. by using withdrawable components or by installation of
separate disconnectors (isolators).
Exception
110 Screening of horizontally installed bus bars
For final feeder circuits where energising of the main switch-
Horizontally installed bus bars and bare conductors or connec- ing device from the load side is not possible, the cable termi-
tions are to be protected by screens, if they are placed such that nals and accessories (e.g. voltage and current transformers)
there could be a risk of anything falling down on them. may be placed in the same compartment as the main switching
111 Clearance and creepage distances device.
See Sec.3 D600 for clearance and creepage distances in 302 Mechanical interlocks
switchgear and assemblies. a) The arrangement in high voltage enclosures is to be such
that all operation and functional testing is safeguarded
B 200 Batteries against accidental touching of live parts.
201 Batteries located in electrical assemblies b) Doors that can be opened for operation or testing of high
a) Batteries may be installed as an integrated part of an elec- voltage parts (e.g. for replacement of fuses, or for func-
tric assembly when the battery is of dry type and has a ca- tional testing of a circuit breaker) are to be interlocked so
pacity less than 0.2 kVAh. that they cannot be opened before the components inside
have been isolated and made safe.
b) Batteries may be installed as a part of an electric assembly
when the capacity of the battery is less than 5 kVAh for c) The openings between the contacts of a withdrawable high
vented type accumulators, and less than 40 kVAh for dry voltage component and the fixed contacts, to which it is
type accumulators and as long as the following is com- connected in service, are to be provided with automatic
plied with: shutters.
Guidance note:
— the batteries shall be separated from the rest of the as-
sembly with flame retardant partitions Front doors of circuit breaker compartments might be opened for
circuit breaker checking or emergency switching, without any in-
— the battery section of the assembly shall have suitable terlocking, if high voltage parts still cannot be reached by acci-
ventilation holes at top and bottom, and be designed dental touching of the hands.
for air circulation upwards. There are not to be pock-
ets that may accumulate gas ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
DET NORSKE VERITAS

303 Control wiring of the circuit. The upper limit of the scale of each voltme-
ter is to be at least 120% of the nominal voltage.
a) The wiring of auxiliary circuits shall, with the exception of
short lengths of wire at terminals of instrument transform- c) Amperemeters, kilowattmeters and voltmeters are to be
ers, tripping coils, auxiliary contacts etc., be either segre- provided with means to indicate rated current or power
gated from the main circuit by earthed metallic partitions and rated voltage, respectively. Instruments are to have ef-
(e.g. metallic tubes) or separated by partitions (e.g. tubes fective screening (e.g. by metal enclosures) in order to di-
or sheathed cables) made of flame retardant insulating ma- minish faulty readings caused by induction from adjacent
terial. current-carrying parts.
b) Fuses of auxiliary circuits, terminals and other auxiliary 105 Kilowatt meters
apparatus requiring access while the equipment is in serv- Normally, a kilowatt meter with connections for reading the
ice, are to be accessible without exposing high voltage actual three-phase load shall be used.
parts.
106 Frequency meters
c) There is to be arranged an alarm for voltage loss after the
last fuses in each auxiliary power system, where a voltage Frequency meters are to have a scale ranging at least 8% above
failure is not self detecting. and below the systems operating frequencies
d) A possibility for manual operation of each circuit breaker 107 Generator instrumentation
is to be arranged. However, manual closing of the circuit a) Each A.C. generator shall be provided with instrumenta-
breakers is not to be possible if the arrangement of the aux- tion showing:
iliary circuits is such that the protection devices are put out
of action and the circuit breakers are still closed after a — current for each phase
power failure to the auxiliary circuits. — voltage
— frequency.
b) When generators are arranged for parallel operation, they
C. Control and Protection Circuits shall in addition be provided with instrumentation show-
ing the active power and be provided with synchronising
C 100 Control and instrumentation devices as required by Sec.2 H105.
101 General c) Simultaneous functional reading of active power and cur-
rent shall be provided at operating station for manual op-
a) See Sec.2 for requirements regarding the distribution sys- eration and synchronisation.
tem for control circuits, and for control and protection of
individual consumers depending of their application and Alternatives
the network system capabilities. Single voltmeters and amperemeters with switches for the al-
b) Power distribution for control circuits are generally to be ternative readings may be accepted.
branched off from the main circuit in which the switchgear Two separate frequency meters for several generators may be
is used, with exceptions as specified in Sec.2 F104. used, one with a change-over switch for connection to all gen-
erators, the other connected to the bus bars. A "double frequen-
102 Control of duplicated consumers cy meter" may be used for this purpose.
a) Control circuits for duplicated essential and important 108 Instrumentation for distribution systems including in
equipment are to be kept separated from each other, and and outgoing circuits of switchboards
not located in the same enclosure. Each secondary distribution system is to be equipped with a
b) Controlgear for duplicated essential or important equip- voltmeter.
ment are to be mutually independent and are to be divided 109 Instrumentation for shore connections
between two motor control centres or distribution boards
having separate supplies from different sides of the main The shore connection circuit shall be equipped with:
switchboard and/or the emergency switchboard. — a phase sequence indicator
c) Where switchboards are fitted with bus ties or bus links, — a voltmeter or signal lamp.
the duplicated circuits shall be fed from different side of
the bus tie.
d) Duplicated equipment for essential or important functions D. Verification and Testing
shall not be dependent on any common circuits such as e.g.
contactors for emergency stop. D 100 General
103 Signal lamps 101 General
Signal lamps are to be arranged so that a lamp short circuit a) Switchgear and controlgear assemblies shall be tested at
cannot jeopardise the control system. the manufacturer’s works as described in 102 to 108.
104 Panel-instruments in general b) The manufacturer shall submit test results together with
the final documentation for the equipment. The documen-
a) Instruments, including current transformers, in switchgear tation shall give information on make, type, serial no., and
and controlgear shall have a nominal accuracy of 2.5% or all technical data necessary for the application of the
better. switchboard or assembly, as well as the results of the re-
b) The upper limit of the scale of ampere-meters and kilo- quired tests.
watt-meters is to be at least 130% of the rated full load of c) The following tests are required:
the circuit. For generators arranged for parallel operation,
the scale is to be arranged for reading of reverse current or — function test: all basic functions, including auxiliary
power corresponding to at least 15% of the rated full load functions, are to be tested
DET NORSKE VERITAS

— insulation resistance test Guidance note:

— high voltage test Electronic equipment should be disconnected, short circuited and
— general inspection of assembly. or isolated during high voltage test and insulation resistance
measuring.
102 Visual inspection ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
Switchboards and assemblies are subject to a visual inspection
for verification of general workmanship, creepage and clear- 107 Power frequency test for high voltage assemblies
ance distances, IP rating, ventilation and quality of materials a) Each high voltage assembly is to be subjected to a 1
and components. minute power frequency voltage test.
103 Function testing b) Replicas reproducing the field configuration of the high
a) All circuits shall be verified installed as shown in the as- voltage connections may replace voltage transformers or
build documentation. power transformers. Overvoltage protective devices may
be disconnected or removed.
b) Control and protection shall be tested for correct function- c) Test voltages are given in Table D1.
ing.
d) Insulation resistance shall be measured prior to and on
104 Load testing completion of the voltage test. Insulation resistance test
The testing of switchgear and controlgear assemblies with full voltages and acceptance values are given in Sec.5 Table
power, eventually together with the intended load, is not re- C3. It shall be verified that the voltage testing does not
quired by these rules. Such tests shall be separately agreed be- cause any reduction in switchgear insulation level.
tween the manufacturer and the customer. e) All auxiliary circuits are to be subjected to a 1 minute volt-
105 Site testing age test between the circuits and the enclosure according
to 106.
Final approval of the switchgear or controlgear assembly shall
include complete function tests with intended loading, after in- Guidance note:
stallation onboard. The environmental conditions during voltage tests are normally
to be as specified in IEC 60060-1, "High-voltage test techniques,
106 Power frequency and insulation resistance test for low Part 1, General definitions and test requirements", that is temper-
voltage assemblies ature 20°C, pressure 1013 mbar and humidity 11 g water per m³
(corresponding to about 60% relative humidity). Correction fac-
a) Switchgear and assemblies with rated voltage above 60 V tors for test voltages at other environmental conditions are given
shall be subject to a voltage test between the circuits and in IEC 60060-1.
between live parts and the enclosure. The test voltage shall ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
be minimum equal to twice the rated voltage plus 1000 V
with a minimum of 1500 V. The test voltage is to be ap- 108 Test voltages for high voltage switchgear assemblies
plied for 1 minute at any frequency between 25 and 100
Hz. Test voltages for high voltage switchgear assemblies are given
in Table D1.
b) For switchgear and assemblies with rated voltage below
60 V, the test voltage given in a) shall be minimum 500 V. Table D1 Test voltages for high voltage assemblies
c) Insulation resistance shall be measured prior to and on Nominal voltage 1 minute power frequency test voltage, (kV)
completion of the voltage test. Insulation resistance test of the system (root mean square value)
voltages and acceptance values are given in Sec.5 Table (kV) 1) To earth and between phases
C3. It shall be verified that the voltage testing does not 1 - 1.1 2.8
cause any reduction in switchgear insulation level. The in- 3 - 3.3 10
sulation level shall be at least 1 MOhm.
6 - 6.6 20
d) The secondary winding of current transformers shall be 10 - 11 28
short circuited and disconnected from earth during the test.
15 38
e) The secondary winding of voltage transformers shall be 1) Intermediate values for test voltages may be accepted, other than these
disconnected during the test. standard test voltages.
DET NORSKE VERITAS

SECTION 5
ROTATING MACHINES
A. General difference between the actual temperature and the temper-

ature given in Sec.3 B300, up to a maximum of 25°C.
A 100 References
b) If the ambient temperatures clearly exceed the maximum
101 General upper limits, then the temperature rises are to be decreased
The design and function of rotating machines shall generally accordingly.
comply with the requirements of IEC 60092-301. For basic c) In Table A1 allowance has been made for the temperature
machine design, the relevant parts of IEC 60034 apply. in certain parts of the machine being higher than meas-
ured. The temperatures at such “hot spots” are assumed
A 200 Requirements common to generators and motors not to exceed the values given in Sec.3 Table F1.
201 Rating or duty
d) For vessels with class notation restricting the service to
a) Electrical machines, including any excitation system, shall non-tropical waters the design limits for temperature rises
be designed for continuous duty. given in Table A1 may be increased by 10°C. Alternative-
ly, the upper ambient air temperature limits according to
b) Unless otherwise clearly stated, the rating of electrical ma- Table A1 may be reduced by 10°C.
chines shall be continuous full load duty type S1.
e) Where water cooled heat exchangers are used in the ma-
c) Generally, maximum environmental temperatures for ro- chine cooling circuit, the temperature rise is to be meas-
tating machines shall be as given in Sec.3 Table B1. ured with respect to the temperature of the cooling water
202 Insulation at the inlet to the heat exchanger. Temperature rises given
in Table A1 may be increased by 8°C provided the inlet
a) All windings for machines are to be treated to resist mois- water does not exceed 32°C.
ture, sea air, and oil vapours. f) If inlet water temperature is above 32°C, permissible tem-
b) For general requirements for insulation materials and ter- perature rise in Table A1 may be increased by 8°C and
minations, see Sec.3 D. then reduced by the amount by which the maximum cool-
ing water temperature exceeds 32°C.
203 Temperature rise in windings (insulation)
g) If the inlet cooling water temperature is permanently less
The maximum permissible heat rise in windings is given in Ta- than 32°C, the permissible temperature rise in Table A1
ble A1, with these deviations: may be increased by 8°C and may be further increased by
an amount not exceeding the amount by which the cooling
a) If the temperature of the cooling medium will be perma- temperature is less than 32°C.
nently lower than the values given in Sec.3 B300, then the
permissible temperature rise may be increased with the
Table A1 Limits of temperature rise of machines for vessels for unrestricted service1) based on ambient temperature of 45°C
Maximum temperature rise in for air-cooled ma-
Method of chines (ºC)
Part of machine 1) measurement of Insulation class
temperature 2)
A E B F H
1. a) A.C. winding of machine having output of 5000 kVA or ETD 60 -3) 80 100 125
more R 55 - 75 95 120
b) A.C. winding of machine having output of less than 5000 ETD 60 - 85 105 125
kVA R 55 70 75 100 120
2. Winding of armature with commutators R 55 70 75 100 120
T 45 60 65 80 100
3. Field winding of A.C. and D.C. machine with excitation R 55 70 75 100 120
other than those in item 4. T 45 60 65 80 100
4. a) Field windings of synchronous machines with cylindrical R 85 105 130
rotors having D.C. excitation
b) Stationary field windings of D.C. machines having more ETD 55 70 85 105 130
than one layer R 45 60 75 100 120
T 65 80 100
c) Low resistance field windings of A.C. and D.C. machines
and compensating windings of D.C. machines having more R, T 55 70 75 95 120
than one layer
d) Single-layer windings of A.C. and D.C. machines with
exposed bare surfaces or varnished metal surfaces and sin- R, T 60 75 85 105 103
gle compensating windings of D.C. machines
1) Temperature rise of any part of a machine shall in no case reach such a value that there is a risk of injury to any insulating or other material in adjacent parts.
2) R indicates temperature measurement by the resistance method, T the thermometer method and ETD the embedded temperature detector method. In gen-
eral for measuring the temperature of the windings of a machine the resistance method shall be applied. (See IEC 60034-1). For stator windings of ma-
chines having a rated output of 5000 kW (or kVA) the ETD method shall be used. Determination by ETD method requires not less than six detectors
suitably distributed throughout the winding. Highest reading shall be used to determine the temperature for the winding.
3) For high voltage machines having rated output of 5000 kVA or more, or having a core length of 1 m or more, the maximum temperature rise for class E
insulation shall be decreased by 5ºC.
DET NORSKE VERITAS

204 Machine short time overloads — make, type, serial no.

— performance standard
a) General purpose rotating machines shall be designed to — IP rating
withstand the following excess torque: — rated values for: output apparent power, voltage(s), fre-
quency, current(s), power factor, speed
— A.C. induction motors and D.C. motors: 60% in ex- — for A.C. machines: the winding connection
cess of the torque that corresponds to the rating, for 15
s, without stalling or abrupt change in speed (under — thermal classification of insulation
gradual increase of torque), the voltage and frequency — duty type, if other than S1
being maintained at their rated value — maximum permissible cooling medium temperature
— A.C. synchronous motors with salient poles: 50% in — technical data necessary for the application of the machine
excess of the torque that corresponds to the rating, for — total mass.
15 s, without falling out of synchronism, the voltage, A 300 Instrumentation of machines
frequency and excitation current being maintained at
their rated values 301 Temperature detectors embedded in stator winding
— A.C. synchronous motors with wound (induction) or All high voltage machines, and low voltage machines having a
cylindrical rotors: 35% in excess of the torque that rated output above 5000 kW (or kVA), are to be provided with
corresponds to the rating, for 15 s, without losing syn- temperature detectors in their stator windings, for monitoring
chronism, the voltage and frequency being maintained and alarm, also see Sec.3 D201.
at their rated value.
Guidance note:
b) Induction motors for specific applications the excess Overvoltage protection may be required for circuits with temper-
torque may be subject to special agreement. See IEC ature detectors.
60034-1 clause 8.3. See Sec.12 A604 regarding rotating machines supplying or driv-
ing electric propulsion and having temperature detectors embed-
c) General purpose rotating machines shall be designed to ded in their stator windings for monitoring and alarm.
withstand the following excess current:
For the requirements in regard to temperature detectors, refer-
— A.C. generators: 50% in excess of the rated current for ence is made to IEC 60034-11.
not less than 30 s, the voltage and frequency being ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
maintained as near the rated values as possible
— A.C. motors: 50% in excess of the rated current for not
less than 120 s, the voltage and frequency being main-
tained as near the rated values as possible
— commutator machines: 50% in excess of the rated cur- B. Additional Requirements for Generators
rent for not less than 60 s, operating at highest full- B 100 General
field speed.
101 General
205 Balance
Exciter and voltage regulation equipment is considered as part
Machines shall be so constructed that, when running at any and of the generator.
every working speed, all revolving parts are well balanced. Guidance note:
206 Lubrication The design of generators shall comply with other relevant parts
of these rules:
a) Lubrication of rotating machines is to be effective under Rules for Classification of Ships, Pt.4 Ch.3 regarding governing
all operating conditions. of auxiliary combustion machines when driving generators.
b) Each self-lubricated sleeve bearings shall be fitted with an DNV-OS-D202 regarding instrumentation equipment and com-
inspection lid and means for visual indication of oil level puter based equipment for monitoring and control.
or use of an oil gauge. Similar requirement applies to self
contained oil lubricated roller bearings.
c) Provision shall be made for preventing the lubricant from 102 Available neutral point
gaining access to windings or other insulated or bare cur- Generators with rating exceeding 1500 kVA, and all high volt-
rent-carrying parts. age generators, shall be prepared for installation of equipment
207 Shafts and shaft currents for short circuit protection of the generator windings.
103 De-excitation
a) Shafts are to comply with the requirements in the Rules for
Classification of Ships, Pt.4 Ch.4 both with regard to Generators with rating exceeding 1500 kVA, and all high volt-
strength, bearings, balancing and certification. age generators, shall be prepared for external signal for initia-
tion of de-excitation of the generator.
b) Means are to be provided to prevent damaging levels of
circulating currents between shaft, bearings and connected 104 Voltage waveform
machinery. For A.C. generators, the voltage is to be approximately sinu-
c) When all bearings on a machine are insulated, the shaft soidal, with a maximum deviation from the sinusoidal curve of
shall be electrically connected to the machine's earth ter- 5% of the peak value.
minal. B 200 Voltage and frequency regulation
208 Machine overspeed 201 Voltage build-up
Rotating machines are to be capable of withstanding 1.2 times a) The construction shall normally be such that the generator,
the rated maximum speed during 2 minutes. when started up, takes up the voltage without the aid of an
209 Nameplate external electric power source.
Each machine is to be provided with nameplate of durable, b) External power sources may be used to take up the voltage
flame retardant material, giving the following information: on main generators provided that redundancy for this ex-
DET NORSKE VERITAS

ternal source is arranged as required for starting arrange- power supplies for AVR’s, undervoltage coils, instruments etc.
ment. connected on the generator side of the generator circuit breaker.
202 Stationary voltage regulation
a) The voltage regulation is to be automatic, suitable for ship- B 300 Generator short circuit capabilities
board condition, and such that the voltage is kept within 301 Short circuit withstand and contribution capabilities
97.5% to 102.5% of the rated voltage under all steady load
conditions. This is between no-load and full-load current A.C. synchronous generators, with their excitation systems,
and at all power factors which can occur in normal use, but shall, under steady short circuit condition be capable of main-
in any case with power factor from 0.7 to 0.9 lagging, also taining, without sustaining any damage, a short circuit current,
taken into consideration the effect of the prime mover's which shall be at least 3 times the rated full load current, for a
speed characteristic. duration of at least 2 s. (IEC 60092-301 modified clause 4.2.3)
b) There is to be provision at the voltage regulator to adjust B 400 Parallel operation
the generator no load voltage.
401 Load sharing
c) The limits in a) may be increased to ±3.5% for emergency
sets. a) Generators for parallel running shall be such that the shar-
ing of active and reactive power is stable under all load
Guidance note:
conditions. Oscillations smaller than ±20% of each gener-
Sec.2 B102 requires that a single failure shall not endanger the ator's rated current can be accepted.
vessel's manoeuvrability, provisions may be necessary for moni-
toring of the voltage regulation. b) In the range 20 to 100% of the rated reactive load of each
generator, its actual reactive load (mean value, if oscilla-
tions occur) is not to differ from its proportionate share of
203 Transient voltage regulation the total reactive load by more than 10% of the rated reac-
tive load of the largest generator in parallel, or not more
a) Maximum values (current and power factor) of sudden than 25% of the smallest generator's rated reactive load, if
loads to be switched on and off shall be specified. Speci- this is less than the former.
fied sudden load should not be less than 60% full load cur-
rent at power factor of 0.4 lagging or less. c) Requirement for sharing of active power is given in the
Rules for Classification of Ships, Pt.4 Ch.3.
b) The voltage variations under transient conditions shall
comply with the following: Guidance note:
The sharing of power is mainly determined by the prime movers'
— when the generator is running at no load, at nominal governor characteristics, to which further requirements are given
voltage, and the specified sudden load is switched on, in the Rules for Classification of Ships, Pt.4 Ch.3. Power oscilla-
the instantaneous voltage drop at the generator termi- tions, however, are determined both by the prime movers' and
nals is not to be more than 15% of the generators nom- generators' characteristics.
inal voltage.
— the generator voltage is to be restored to within ±3%
of the rated voltage within 1.5 s. 402 Parallel operation on nets with earthed neutral
— when the specified sudden load is switched off, the in-
stantaneous voltage rise is not to be more than 20% of When generators are run in parallel on nets with earthed neu-
the rated voltage. tral, it is to be ensured that the equalising current resulting from
— the generator voltage is to be restored to within ±3% harmonics does not exceed 20% of the rated current of each
of the rated voltage within 1,5 s. generator.
c) For non-paralleling emergency generating sets the regula-

tion limits and time in b) might be increased to ±4% within
5 s. C. Verification and Testing
d) Under fault conditions, inclusive faults in the AVR's cir- C 100 Factory testing
cuit, the generator voltage shall not exceed 120% of the
rated voltage. 101 General
e) On installations where two or more generators are normal- a) Electrical machines shall be tested at the manufacturer’s
ly run in parallel, the maximum load that can be switched works with the tests specified in this part of the rules. Type
on may be divided between the generators in relation to tests shall be carried out on a prototype of a machine or the
their rating and expected maximum duty as individual first of a batch of machines. Routine tests shall be carried
generator. out on each machine.
f) See the Rules for Classification of Ships, Pt.4 Ch.3 and b) The type tests (TT) and routine tests (RT) that the ma-
Sec.2 E102 for requirements for the governor of a genera- chines shall undergo are listed in Table C1
tor prime mover.
c) The tests in Table C1 shall be documented. The documen-
Guidance note: tation shall give information on make, type, serial no., in-
Special consideration should be given to the overvoltage that sulation class, all technical data necessary for the
may occur when switching off the generators at full load or over- application of the machine, as well as the results of the re-
load. This overvoltage should not reach a level that may damage quired tests.
DET NORSKE VERITAS

d) The result of type tests, and the serial number of the type
tested machine, shall be specified in the documentation of
test results for a routine tests.
Table C1 Testing and inspection of electrical machines

No. Task Required test for Required test for mo-
generators tors
1 Examination of technical documentation. Air gap to be measured or verified.1) TT, RT TT, RT
2 Visual inspection, verification of data on name plate. TT, RT TT, RT
3 Verification of degree of enclosure protection (IP). TT TT
4 During the running tests, the vibration or balance of the machine including operation of the TT, RT TT, RT
bearing or lubrication system. Reference: 34-14 (1996-11)
5 Overspeed test: 20% in excess of the rated r.p.m. for 2 minutes. TT TT
6 High voltage test, 1 minute. TT, RT TT, RT
7 Winding's resistance to be measured. TT, RT TT, RT
8 Temperature-rise test at full load. TT TT
9 Measurement of insulation resistance. TT, RT TT, RT
10 No load current at rated voltage and frequency. TT, RT
11 Locked rotor test at rated current. 2) TT, RT
12 Overload or overcurrent test (IEC 60034-1/8.2 and 8.3). TT TT
13 A.C. generator: Measuring of voltage regulation during steady and transient loading and TT, RT
unloading, see Sec.2 A 204.
14 A.C. generator: Measuring of open circuit voltage characteristics (no load curve). TT, RT
15 A.C. generator: Measuring of short circuit characteristics (short circuit curve). TT, RT
16 A.C. synchronous motor or generator: Measuring of excitation current at rated voltage, cur- TT, RT TT, RT
rent and power factor.
17 A.C. Synchronous generator: Measuring of steady short circuit condition. TT
18 For high voltage machines a steep fronted impulse test, or equivalent, of the coil interturn
insulation is to be carried out according to IEC 60034-15.
Tests on each separate fully processed coil after inserting in the slots are preferred. Due to RT RT
various technologies involved, alternative proposals to verify withstand level of interturn
insulation may be considered, e.g. type tests with fully produced sample coils.
1) Measuring of air gap only for machines of size 1.5 MVA and above.
2) For A.C. induction motors only.
Guidance note: and marked, in accordance with the testing methods speci-
Overspeed test (5) fied in IEC Publication No. 60034-1.
Dielectric test to be performed on rotors after overspeed test IEC b) For machines with maximum continuous rating (duty type
60034-1-8.5. S1), the temperature rise test shall be continued until ther-
mal equilibrium has been reached, that is when the temper-
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- ature rise varies by not more than 2°C over a period of 1 h.
c) For acceptable methods of winding temperature measure-
Guidance note: ment and corresponding maximum temperatures, please see
High voltage tests (6) Table A1. See guidance note below about the variety of tem-
perature measurement methods.
a) A 1 minute high voltage test is to be applied to a new and
completed machine with all its parts in place under condi- d) The measurement of final winding temperature at end of the
tions equivalent to normal working conditions. The test is to test is to be performed within the time limits given in Table
be in accordance with IEC 60034-1-8.1 "Dielectric tests", C2.
and is to be carried out at the maker's works at the conclu- e) If measurement of final winding temperature are to be car-
sion of the temperature-rise test. ried out by resistance measurements according to Table C2,
the temperature has to be measured as a function of time af-
b) For voltage levels to be used, please see IEC 60034-1 Table ter shutdown, and correct temperature determined by ex-
14, normally (for ac windings of machines between 1 kW trapolation back to the initial switch off time point.
and 10.000 kW) the test voltage is 1000 V + twice the rated
voltage with a minimum of 1500 V. f) The initial reading shall never be delayed more than twice
the time limits given in Table C2. (See IEC 60034-1 7.6.2
c) After rewinding or other extensive repair of a machine, it is for extended guidance on this subject).
to be subjected to a high voltage test with a test voltage of at
least 75% of that specified in IEC 60034-1-8.1.
Table C2 Resistance measurement time after switch off
d) On carrying out high-voltage test, it may be necessary to Rated output, P Time delay after switching off
short circuit semi-conductors in order to avoid damage of (kW) (kVA) power
such parts. (s)
P ≤ 50 30
50 < P ≤ 200 90
Guidance note: 200 < P ≤ 5000 120
Temperature rise measurement and testing (8) 5000 < P By agreement
a) The temperature rise of a machine is to be measured at the g) When the resistance method is used, the temperature for
rated output, voltage and frequency, and the temperature test copper windings, Θ1 - Θ2, may be obtained from the ratio of
is to be carried out at the duty for which the machine is rated the resistances by the formula:
DET NORSKE VERITAS

Θ 2 + 235 R — "Equivalent loading of induction machines for temperature

---------------------- = -----2- test". IEEE Transactions on Power Apparatus and Systems
Θ 1 + 235 R1 Volume Pas-96 No.4, July/August 1977, pages 1126-1131.
Author: Schwenk H. R. (19).
Θ2 = winding temperature at the end of the test
Θ1 = winding temperature at the moment of the initial resist- ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
ance measurement.
The temperature rise is the difference between the winding Guidance note:
temperature at the end of the test, and the ambient air tem-
perature at the end of the test. (Alternatively the water inlet Insulation resistance test (9)
temperature at the end of the test, for water/air heat exchang-
ers.) a) The insulation resistance of a new, clean dry machine, is to
be measured immediately after the temperature test has been
The resistance of a machine winding is to be measured and carried out and after high voltage test has been carried out
recorded using an appropriate bridge method or voltage and using a direct current insulation tester between:
current method.
h) When the embedded temperature detector (ETD) method is — all current carrying parts connected together and earth
used, there shall be at least six detectors suitably distributed — all current carrying parts of different polarity or phase,
throughout the machine windings. They shall be located at where both ends of each polarity or phase are individu-
the various points at which the highest temperatures are like- ally accessible.
ly to occur, and in such a manner that they are effectively
protected from contact with the coolant. The highest reading The minimum values of test voltage and insulation are given
of an ETD element shall be used to determine compliance in Table C3. The temperature at which the resistance is
with requirements for temperature limits. measured is to be near the operating temperature, or an ap-
i) When there is two or more coil-sides per slot, the ETD ele- propriate method of calculation may be used.
ments shall be placed between the insulated coil sides. If b) On carrying out insulation resistance test, it may be neces-
there is only one coil-side per slot, the ETD method is not a sary to short circuit semi-conductors in order to avoid dam-
recognised method for determination of temperature rise or age of such parts.
temperature limits in order to verify the compliance of the
rating.
j) The thermometer method is recognised in the cases in which
neither the ETD method nor the resistance method is appli- Table C3 Minimum insulation resistance values
cable. See IEC 60034-1 for guidance. The measured temper-
ature rises shall not exceed the following values: Rated voltage Minimum test Minimum insulation
Un (V) voltage (V) resistance (MΩ)
65 K for class A insulation
Un ≤ 250 2 x Un 1
80 K for class E insulation
90 K for class B insulation 250 < Un ≤ 1000 500 1
115 K for class F insulation 1000 < Un ≤ 7200 1000 (Un / 1000) + 1
140 K for class H insulation. 7200 < Un ≤ 15000 5000 (Un / 1000) + 1
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- Guidance note:
Guidance note: Overload testing (12)
Alternative methods for temperature rise calculations Overloads as stated in A204 are difficult to test on large ma-
Temperature tests at full load may be difficult to realise for large chines. In case overloads cannot be tested, documentation or cal-
machines, due to insufficient test power being available. One of culations based on manufacturers proven methods and
the following simulated tests, or equivalent, will be subject for experience will be accepted.
approval for synchronous generators and induction motors:
— synchronous feedback, or back to back method, according to
IEEE Std. 115-1983, 6.2.2 102 Site testing
— zero power factor method, according to IEEE Std. 115-
1983, 6.2.3 a) All machines shall be tested at site, after installation, so
— open-circuit and short circuit loading method, according to that acceptable starting and running performance are veri-
IEEE Std. 115-1983, 6.2.4 fied with full capacity of driven equipment, alternatively
— "Erwaermungsmessungen an Asynchron-Motoren mit Hilfe full generator load.
des Zweifrequenzverfahrens" "Brown Boveri Mitteilungen"
8-1976 b) Setting of motor protection shall be verified.
DET NORSKE VERITAS

SECTION 6
POWER TRANSFORMERS
A. General — insulation class 220: 140°C
A 100 General b) Liquid immersed transformers:

101 Reference — temperature rise for windings: 55°C
The design of transformers shall in general comply with the re- — temperature rise for liquid when the liquid is in con-
quirements of IEC 60092-303. (In addition, dry type trans- tact with air: 45°C
formers shall comply with IEC 60726, and liquid cooled — temperature rise for liquid when the liquid not is in
transformers with IEC 60076, as referenced to in IEC 60092- contact with air: 50°C.
303.)
204 Parallel operation
A 200 Design requirements for power transformers Transformers for parallel operation are to have compatible
201 General coupling groups and voltage regulation, so that the actual cur-
rent of each transformer will not differ from its proportionate
a) Transformers shall be double wound. Starting transform- share of the total load by more than 10% of its full load current.
ers may be of autotransformer type.
205 Voltage regulation
b) Normally, transformers are to be of the dry air-cooled
type. Transformers supplying secondary distribution systems for
general use shall normally have a maximum 2.5% voltage drop
c) All windings for air-cooled transformers are to be treated from no load to full load at resistive load.
to resist moisture, sea air, and oil vapours.
206 Short circuit withstand and protection
d) For the general requirements for insulation materials and
terminations, see Sec.3 D. Transformers are to be constructed to withstand a primary or
secondary terminal short circuit with a duration of minimum 1
202 Liquid immersed transformers s, with rated primary voltage and frequency, without damage
to internal parts or enclosure.
a) Liquid immersed transformers, filled with non-flammable 207 Forced cooling
liquid, may be accepted in engine rooms or similar spaces
if they have provision, when installed, for containing or Power transformers with forced cooling shall be equipped with
safe draining of a total liquid leakage. temperature detectors for monitoring and alarm as required by
Sec.3 D200.
b) Normally, liquid immersed transformers are to be of the
sealed type. However, conservator type may be accepted 208 Enclosure requirement
if the construction is such that liquid is not spilled, when Transformers for separate installation are to have separate en-
the transformer is inclined at 40°. closures complying with the IP protection requirements, in re-
c) Liquid immersed conservator type transformers shall have lation to its intended location, as stated in Sec.10, Table B1.
a breathing device capable of stopping (trapping) moisture 209 Nameplate
from entering into the insulating liquid.
Each power transformer is to be provided with nameplate of
d) Arrangement for containment of accidental leakage shall durable, flame retardant material, giving the following infor-
be arranged. mation:
e) A liquid gauge indicating the normal liquid level range
shall be fitted. — make, type, serial no.
f) Liquid immersed transformers shall be provided with — rated values for: output apparent power, voltage(s), fre-
monitoring as required in Table A1. quency, current(s), power factor
— duty type, if other than S1
Table A1 Monitoring of liquid immersed transformers — thermal classification of insulation
Item Alarm Load reduc- Comments — IP code of enclosure and termination box
tion or trip — vector group of windings
Liquid level, low X X — maximum permissible cooling medium temperature
Liquid temperature, high X X — short circuit impedance value
Gas pressure, high X Trip — liquid type (if applicable)
Interturn short circuit X Trip — total mass.
203 Temperature rise
Temperature rise for transformers, above ambient, according
to Sec.3 B300, shall not exceed the following values (meas- B. Inspection and Testing
ured by the resistance method):
B 100 General
a) Dry type transformer windings: 101 Factory testing
— insulation class A: 50°C a) Transformers shall be tested at the manufacturer’s works
— insulation class E: 65°C with the tests specified in this part. Tests noted as type
— insulation class B: 70°C tests (TT) shall be carried out on a prototype or the first of
— insulation class F: 90°C a batch of identical transformers. Tests noted as routine
— insulation class H: 115°C tests (RT) shall be carried out on each transformer.
DET NORSKE VERITAS

b) Required inspection and tests for distribution transformers c) The test is to be applied between each winding and the oth-
above 5 kVA rating is the following: er windings, frame and enclosure all connected together.
The test is to be made with an A.C. voltage at the level 1
— inspection of enclosure, terminations, and instrumen- kV plus twice the winding's rated voltage, with a mini-
tation or protection (RT) mum of 2.5 kV. The frequency can be chosen between 25
— temperature rise test (TT) Hz and twice the rated frequency.
— measuring of insulation resistance (RT)
— high voltage power frequency test (RT) d) New transformers up to and including 5 kVA rating are to
— measuring of voltage ratio at no load (RT) withstand an applied high voltage test as specified in a)
— measuring of winding resistance (RT) above, but without the requirement of minimum 2.5 kV
— short circuit voltage or impedance, no load and full- test voltage in case of a lower rated voltage.
load losses (TT)
— short circuit test can be required as routine test or type e) The full test voltage is to be maintained for 1 minute.
test. f) Single phase transformers for use in a polyphase group are
to be tested in accordance with the requirements for the
c) The tests shall be documented. The documentation shall transformers as connected together in the system.
give information on make, type, serial no., insulation
class, all technical data necessary for the application of the g) After rewinding or other extensive repair the transformer
transformer, as well as the results of the required tests. is to be subjected to a high voltage test with a test voltage
d) The result of type tests, and the serial number of the type of at least 75% of that specified in c) and d) above.
tested transformer, shall be specified in the documentation
of test results for a routine test. 104 Insulation resistance testing
e) For testing at site, after installation, see Sec.10. The insulation resistance of a new, clean dry transformer is to
be measured immediately after the temperature rise test, when
102 Temperature rise test such is required, and the high voltage test has been carried out.
Temperature test at full load may be difficult to realise on large Test voltage and minimum insulation resistance is given in Ta-
transformers, due to insufficient test power being available. ble B1. The test is to be carried out between:
One of these simulated tests, or equivalent will be subject for
approval: — all current carrying parts, connected together, and earth
— all current carrying parts of different polarity or phase,
— back to back method, according to IEC 60726. Clause where both ends of each polarity or phase are individually
21.1.2. accessible.
— simulated load method, according to IEC 60726. Clause
21.1.3. Table B1 Test voltages and minimum insulation resistance
Rated voltage Un (V) Minimum test Minimum insulation
103 High voltage testing voltage (V) resistance (MΩ)
a) A high voltage test is to be applied to a new and completed Un ≤ 250 2 x Un 1
transformers. 250 < Un ≤ 1000 500 1
b) The test is to be carried out immediately after the temper- 1000 < Un ≤ 7200 1000 (Un / 1000) + 1
ature rise test, when such is required. 7200 < Un ≤ 15000 5000 (Un / 1000) + 1
DET NORSKE VERITAS

SECTION 7
SEMI-CONDUCTOR CONVERTERS
A. General Requirements c) As a motor starter, the converter shall as a minimum with-

stand two consecutive start attempts without being over-
A 100 General loaded by temperature.
101 References d) For converter assemblies supplying motors, required
torque is to be considered in view of the application.
a) The design of semi-conductor assemblies shall comply
with the requirements of IEC 60092-304. 302 Output voltage
b) Static converters assemblies based on semi-conductor de- Requirements for supply systems in Sec.2 are regarded as rel-
vices for installation in the power system are to comply evant for secondary side of converter assemblies applied to
with the requirements given in this chapter. supply a constant frequency or constant voltage output.
303 Short circuit current capabilities
Guidance note:
Converter assemblies serving as power supplies shall be able
See Sec.4 for the requirements for electrical assemblies.
to supply a short circuit current sufficient for selective tripping
See DNV-OS-D202 regarding instrumentation equipment and of downstream protective devices, without suffering internal
computer based equipment. damage.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 304 Protection and monitoring
102 Electromagnetic compatibility a) Monitoring facilities in the control unit shall normally be
provided to identify faults in the control or power circuits.
a) Converter assemblies shall be compatible with the ship
network, so that generated line harmonics do not cause in- b) Inverters shall have the possibility for monitoring of the
terference with other equipment. output voltage, frequency and current.
b) Transformers and reactors applied in connection with con- c) See Sec.2 G103 with respect to protection of batteries.
verter assemblies shall be designed to withstand any addi- 305 Parallel operation
tional stresses caused by non-sinusoidal voltages and
currents. a) When converter assemblies are operated in parallel with
other power sources, the control circuits are to ensure sta-
Guidance note: ble parallel operation and prevent overloading of any unit.
See Sec.2 with respect to requirements for system voltage, fre-
quency and harmonic distortion. b) When a converter system has parallel power circuits the
load shall be distributed equally between the parallel
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- paths.
103 Environmental conditions 306 Nameplate
The power part of a converter unit shall comply with the envi- Each semi-conductor assembly is to be provided with name-
ronmental conditions given in Sec.3. Instrumentation and con- plate of durable, flame retardant material, giving the following
trol equipment integrated in a converter shall comply with the information:
requirements in DNV-OS-D202.
— make, type, serial no.
A 200 Mechanical requirements — rating
201 Accessibility — IP code
Stacks of semi-conductor elements, fuses in the power circuit — rated input voltage and frequency
or other equipment likely to be changed out, are to be so ar- — rated output voltage, frequency, current
ranged that they can be removed from equipment without dis- — rated ambient temperature
mantling the complete unit. — rated cooling water temperature (if applicable).
202 Cooling
Where forced cooling is provided, the apparatus is, unless oth-
erwise particularly required, to be so arranged that the convert- B. Testing
er cannot remain loaded unless effective cooling is provided,
or other effective means of protection against over temperature B 100 Testing
is provided. 101 General
A 300 Design requirements, electrical, for semi-conduc- a) Converter assemblies shall be tested at the manufacturer’s
tor assemblies works. Type tests (TT) shall be carried out on a prototype
301 Electrical rating and duty of a converter or the first of a batch of identical converters.
Routine tests (RT) shall be carried out on each converter.
a) The specified converter assembly capacity shall at least in- b) The tests shall be documented The documentation shall
clude a 100% continuous load, and a specified overload give information on make, type, serial no., insulation
capacity given by a current of maximum duration. class, all technical data necessary for the application of the
b) Where required by the application, the overload capacity converter, as well as the results of the required tests.
may be specified in several steps with corresponding max- c) The result of type tests, and the serial number of the type
imum duration, or the converter rated load may be referred tested converter, shall be specified in the documentation of
to a worst case duty cycle. test results for a routine tests.
DET NORSKE VERITAS

d) All converter assemblies are to withstand a high voltage Guidance note:

test of duration 1 minute applied between the terminals In case short circuit capability cannot be tested, documentation
and earthed parts, with frequency between 25 Hz and 100 or calculations based on manufacturers proven methods and ex-
Hz as described in Sec.4 D100. perience will be accepted.
e) The following tests are required: ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
— Function test (RT): All basic functions, including aux- 102 Load testing
iliary functions, are to be tested under light load con- Factory acceptance testing of semi-conductor converters with
ditions. Input voltage and frequency are to be varied full power, together with the intended load if relevant, is not re-
according to Sec.2 if applicable. Main output charac- quired for certification in accordance with these rules. Such
teristics are to be measured. tests shall be separately agreed between the manufacturer and
— Current test (TT): Full load current and over current the customer. (See 103 for site testing.)
test according to rating as required in A301 a).
— Insulation resistance test (RT). 103 Site testing
— High voltage test (RT).
— Short circuit current capability test for power supplies a) Final approval of the semi-conductor assembly shall in-
(TT). See A303. clude complete function tests with intended loading, after
— General inspection of assembly (RT). See Sec.4 for installation onboard, including a discharge test for UPS
relevant assembly requirements. and D.C. power supplies.
b) The functional tests of semi-conductor power converters
intended for rotating machines shall be performed with all
ship systems simultaneously in operation, and in all char-
acteristic load conditions.
DET NORSKE VERITAS

SECTION 8
MISCELLANEOUS EQUIPMENT
A. General — socket outlets on systems with voltage below 50 V

A.C. or D.C.
A 100 Battery boxes and lockers — socket outlets with double insulated transformers for
101 References handheld equipment
— socket outlets in dry accommodation spaces where
Other requirements for batteries, and battery installation, are floor covering, bulkhead and ceiling linings are of in-
found in Sec.2 D100, Sec.2 I300, Sec.4 B200 and Sec.10 sulating material.
B300.
102 Marking g) Precautions are to be taken so that a plug for one voltage
cannot be inserted in a socket outlet for a different voltage.
All batteries are to be provided with nameplates of flame re- Alternatively, warning signboards are to be fitted.
tardant material, giving information on the application for
which the battery is intended, make, type, voltage and capaci- A 300 Lighting equipment
ty. Instructions are to be fitted either at the battery or at the
charging device, giving information on maintenance and 301 General
charging. a) The temperature rise of parts of luminaries that are in con-
103 Battery boxes and lockers tact with the support shall generally not exceed 50°C.
a) Dedicated battery boxes shall have ventilation holes at the b) The temperature limit is 40°C for parts installed in contact
top. There are not to be pockets that may accumulate gas. with flammable materials, such as for example wood.
b) In battery boxes, the cells shall be placed at one height on- c) For temperature rise of terminals: see Sec.3.
ly. d) For other parts, temperatures according to recognised na-
c) In battery boxes with side cover there shall be a minimum tional or international standards, which take due consider-
of 300 mm space above each cell. In battery boxes with a ation of the ambient temperatures on vessels, will be
top cover there shall be a minimum of 300 mm space accepted.
above each cell when the cover is open. e) Normally, gas discharge lighting equipment shall not be
d) Normally, boxes shall not contain electrical equipment used.
other than intrinsically safe monitoring devices. Lighting,
if necessary shall be mounted outside the box or locker. 302 Lampholders
104 Battery lockers a) Types of lampholders according to Table A1 may be used.

The requirements for battery boxes are also applicable to bat- b) Lampholders of type E40 should be provided with an ef-
tery lockers. In addition, the following requirements apply: fective means for locking the lamp in the holder.
c) All lampholders for incandescent lamps with a rating
— the locker shall be prepared for an exhaust duct above 5 W shall be made of incombustible material.
— the batteries may be assembled at several heights, with a
minimum free distance between each of 300 mm. d) It shall not be possible to insert a lamp for one voltage into
a lampholder for a different voltage unless warning sign-
A 200 Socket outlets and plugs boards are fitted.
201 General
Table A1 Accepted type of lampholders
a) Socket outlets and plugs with a rated current not exceeding Designation Maximum lamp rating
63 A in A.C. installations and 16 A in D.C. installations, Voltage Load
shall be constructed for making and breaking the rated cur- 3000 W
rent by insertion and withdrawal of the plug, unless they E 40 250 V 16 A
are provided with an interlock as described in b). Lampholders for 200 W
1. screw cap lamps E 27 250 V
b) Socket outlets with a rated current above 63 A A.C. or 16 4A
A D.C. shall be provided with interlocks so that the plug 15 W
can only be inserted and withdrawn when the switch is in E 14 250 V 2A
the "off" position. 200 W
B 22 250 V 4A
c) The maximum voltages for socket outlets is normally 250
V. Lampholders for bay-
2. onet cap lamps B 15d 250 V
15 W
2A
d) Socket outlets for portable appliances, which are not hand-
held during operation (e.g. welding transformers, refriger- 15 W
B 15s 55 V 2A
ated containers), shall be interlocked with a switch regard-
less of rating, maximum 1000 V can be accepted. At each Lampholders for tab- G 13 250 V 80 W
such socket outlet, a warning sign is to be fitted, with text: 3. ular fluorescent
lamps G5 250 V 13 W
DANGER (maximum voltage) V A.C. ONLY FOR CON-
NECTION OF.... (type of equipment).... The designations for 1. are according to IEC 60238, for 2. and 3. to
IEC 60061 - 2. The voltage and current ratings of 1. are according to
e) Higher voltage socket outlets can only be used for special IEC 60238, except for E14, the power rating of 3. to IEC 60061 - 2.
applications.
f) All socket outlets shall be provided with an earthing con- 303 Starting devices
tact, except that this may be omitted in the following cas- Starting devices which develop higher voltages than the supply
es: voltage are generally to be placed within the luminaries.
DET NORSKE VERITAS

304 Discharge of capacitors 406 Water heaters

Each capacitor of 0.5 µF or more shall be provided with an ar- a) Water heaters are normally to have insulated heating ele-
rangement that reduces the voltage to not more than 50 V with- ments and shall be installed as separate units.
in 1 minute after disconnection from the supply.
b) The requirements for temperature rises specified for cook-
A 400 Heating equipment ing equipment in 500 apply.
401 General c) Each water heater shall be provided with a thermostat,
Each separate heating element rated more than 16A is consid- sensing the water temperature and maintaining this at the
ered as a separate consumer, for which a separate circuit from correct level.
a switchboard is required. Guidance note:
402 Temperature rises for heaters Electrode heaters and electrically heated steam boilers may be
The temperature rises in Table A2 are accepted. accepted after assessment of the arrangement in each case.
Heating by electric elements in the ship's water tanks may be ac-
Table A2 Temperature rises for heaters cepted after design assessment of the arrangement in each case.
Part Temperature For pressure vessels, the requirements in the Rules for Classifi-
(°C) cation of Ships, Pt.4 Ch.7 apply.
Enclosure parts against the bulkhead 60 ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
Operating handles, if of metal 35
Operating handles, if of insulating material 60 407 Oil heaters
Other accessible parts 130 1) a) Electric oil heaters are normally to be installed as separate
Surface of heating elements inside enclosures 280 units. Heating by electric heating elements in the ship's oil
with through air convection tanks is generally not allowed, but may be accepted after
1) Heating elements having a temperature rise exceeding 130°C are gen- special design assessment of the arrangement in each case.
erally to be considered as "live parts" and shall be provided with suita-
ble enclosures. b) The requirements for temperature rises specified for cook-
ing equipment in 500 apply. In addition, the surface tem-
Guidance note: perature of the heating elements shall be below the boiling
It is recommended to provide each heater with an interlocked point of the oil, under normal working conditions. Further
over temperature thermostat with manual reset, accessible only limitation of the heating elements' temperature may be re-
by use of a tool. National regulations of the flag state might required.
quire such an over temperature cut out.
c) Each oil heater shall be provided with a working thermo-
stat, sensing the oil temperature and maintaining this at
403 Space heaters correct level under normal working conditions. In addi-
tion, each oil heater shall be provided with an interlocked
a) Space heaters are generally to be of the convection type, over-temperature thermostat with manual reset, and with
and suitable for installation on bulkheads. Radiation heat- the sensing device installed in close proximity to the heat-
ers and other space heater types may be accepted after con- ing elements, so arranged that it will trip the elements,
sideration in each case. should they tend to overheat, or become dry. Other ar-
rangements, ensuring equivalent protection, may be ac-
b) Space heaters are generally to be constructed with the top cepted after design assessment in each case
plate inclined about 30°, tight against the bulkhead in or-
der to prevent clothing or other flammable material from Guidance note:
covering the heaters. Lubricating oil may deteriorate even at much lower element tem-
c) Space heaters are normally to be installed on a free bulk- peratures. The oil manufacturer should be consulted regarding
head space, with about 1 m free air above, and so that for the maximum acceptable element temperature.
example doors cannot touch the heaters. If not constructed ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
as specified in b), an inclined perforated plate of incom-
bustible material shall be mounted above each heater. 408 Heating cables, tapes, pads, etc.
Space heaters are not to be built into casings of woodwork
or other combustible material. a) Heating cables, tapes, pads, etc. are not to be installed in
contact with woodwork or other combustible material. If
404 Heating batteries for ventilation systems installed close to such materials, a separation by means of
For heating batteries in ventilation systems, the heating ele- a non-flammable material may be required.
ments shall be interlocked with the fans, and both a working b) Earth fault breakers shall be provided with a maximum re-
thermostat and an over-temperature thermostat with manual lease current of normally 30 mA. For heat trace installa-
reset are required. tions a maximum release current of 300 mA is accepted.
405 Space heaters combined with air-condition cabinets c) Heat tracing shall not expose surroundings or insulated
The following additional requirements apply for space heaters piping material to higher temperature than the material is
integrated in air-conditioning cabinets: suited for.
— the maximum temperature rises specified in 402 shall be A 500 Cooking and other galley equipment
complied with, even when the air supply is completely 501 General
shut off
— each cabinet shall be provided with an interlocked over a) Cooking equipment is generally to have insulated heating
temperature thermostat with manual reset, accessible only elements. Special equipment, such as for example high
by use of tool frequency ovens or electrode pots, are to be suitable for
— combined cabinets for ceiling installation are accepted, the marine use, and installed in accordance with the manufac-
ceiling shall be constructed of incombustible materials. turer's instructions.
DET NORSKE VERITAS

b) Electrode pots giving earth -connection of the system shall Table A3 Temperature rises cooking and other galley
be fed from separate isolating transformers. equipment
c) For oil pots, the requirements for oil heaters in 407 apply Part Temperature
d) The temperature rises in Table A3 are accepted. (°C)
Enclosure parts against the bulkhead and decks 50
Operating handles, if of metal 25
Operating handles, if of insulating material 50
Other accessible surface parts, except hot plates 50
with adjacent top plates
Hot plates with adjacent top plates, and heating No limit 1)
elements
1) Construction and temperatures shall be such that damage and hazards
are avoided, when the equipment is used as intended.
DET NORSKE VERITAS

SECTION 9
CABLES
A. Application Guidance note:

Class 5 will be in amendment 3 of IEC 60092-353.
A 100 General ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
101 General
102 Conductor cross section
a) This section of the rules contains requirements for selec-
tion, construction and rating of fixed electrical cables for a) Conductor cross sections shall be based on the rating of the
permanent installation. Other applicable requirements in over current and short circuit protection used. However
other sections shall also be complied with. the minimum cross section shall be:
b) For flexible cables, the requirements apply only as far as — 0.22 mm2 for data cables
practicable. The use of flexible cables shall be limited to — 0.5 mm2 for 60 V cables
applications where flexibility is necessary, and the lengths — 1.0 mm2 for 250 V and 0,6/1 kV cables with the fol-
of such flexible cables shall be kept as short as practicable. lowing exceptions: 0.75 mm2 may be used for flexible
Special requirements may be made for the type, installa- cables supplying portable consumers in accommoda-
tion and protection of flexible cables, depending upon the tion spaces, and also for internal wiring of lighting fit-
application. tings, provided that the full load current is a maximum
c) Requirements for cables for special applications are found of 6 A and that the circuit's short circuit protection is
in other parts of the rules. For cable selection see Sec.2 and rated at a maximum of 10 A
for cable installation see Sec.10. — 10 mm2 for voltages above 1 kV.
102 Duty b) Minimum cross sections of earth conductors are given in

Sec.2. Earth conductors in cables shall be insulated, except
a) Unless otherwise clearly stated, the rating of electrical ca- for earth conductors as specified in Sec.2 Table J2.
bles for power supply to equipment shall be for continuous c) For current rating of cables see Sec.2 J.
full load duty. Maximum environmental temperatures
shall be as given in Sec.3 Table B1.
b) Requirements for cable sizing, and the tables for the cur-
rent rating of different cable sizes, can be found in Sec.2. C. High Voltage Cables
103 Compliance with IEC C 100 General
The design of all electrical cables installed shall comply with 101 Construction of high voltage cables
the requirements of applicable IEC Publications. a) Types of cables and insulated conductors shall comply
Guidance note: with the requirements for cable construction in B.
b) The construction and testing of cables for permanent in-
1) The construction of power cables for permanent installa- stallations shall normally comply with the recommenda-
tions should normally comply with the specifications of In-
ternational Electrotechnical Commission's (IEC) tions of IEC 60092-354, "Electrical installations in ships,
Publication No. 60092-353. «Electrical installations in Part 354: Single- and three-core power cables with extrud-
ships, Part 353: Single and multicore non-radial field power ed solid insulation for rated voltages 6 kV, 10 kV and 15
cables with extruded solid insulation for rated voltage 1 kV kV", and IEC 60502, "Extruded solid dielectric insulated
and 3 kV». power cables for rated voltages from 1 kV to 30 kV", with
2) In IEC 60092-350, 0,6/1,0 kV gives as rated voltages for the following additional requirements:
ship power cables.
— as insulating materials only cross linked polyethylene
3) IEC 60092-3 has been withdrawn, however until a new IEC (XLPE) or ethylene propylene rubber (EPR) shall be
standard for 150/250 V cables has been issued, IEC 60092- used as listed in IEC 60092-351
3 should be used. — conductor screening is required for all cables with
4) Cables intended for use on systems operating up to 60 V XLPE insulation, and for EPR-insulated cables with
A.C. or D.C. should comply with IEC 60092-375. rated voltage U0/U above 3,6/6 kV. Conductor screen-
5) Cables intended for use on systems operating up to 250 V ing shall be non-metallic and consist of either semi-
A.C. or D.C. (not susceptible to interference) should comply conducting tape or a layer of extruded semi-conduct-
with IEC 60092-376. Only for 1 mm2 conductors. See 3) ing compound, or a combination of the two
above. — insulation screening is required for all cable and shall
consist of a non-metallic semi-conducting part in con-
tact with a metallic part (see further IEC 60092-354)
— as sheath materials one of the types specified in IEC
60092-359 shall be used
— wire braid and armour shall comply with the require-
B. General Cable Construction ments in D300.
B 100 General Guidance note:
Other constructions and materials will be accepted when special-
101 Conductors ly designed for special purposes.
All conductors shall be stranded according to IEC 60228 class For example «fire resisting» cables for circuits with short time
2 or class 5. duty (such as fire pumps), since the need for fire resisting char-
DET NORSKE VERITAS

acteristics of such cables make it difficult to apply screening as Table D2 Minimum average thickness of insulating walls
specified above.
(Continued)
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 150 1.8 1.8 1.4
185 2.0 2.0 1.6
240 2.2 2.2 1.7
300 2.4 2.4 1.8
Designation of the insulating compound
D. Low Voltage Power Cables
EPR XLPE
D 100 Cables rated 0.6/1 kV and 1.8/3 kV Nominal cross HF EPR HF XLPE
section of con- HEPR
101 Insulating materials ductor (mm2) (mm) HF HEPR
(mm)
a) The temperature classes and materials given in Table D1 Rated voltage 1.8/3 kV
may be used. 10 2.2 2.0
16 2.2 2.0
Table D1 Temperature classes for insulating materials 25 2.2 2.0
Material Temperature 35 2.2 2.0
(°C) 50 2.2 2.0
Polyvinyl chloride or (PVC) 60 70 2.2 2.0
95 2.4 2.0
Ethylene propylene rubber (EPR) 85 120 2.4 2.0
Halogen free ethylene propylene rubber 85 150 2.4 2.0
(HF EPR) 185 2.4 2.0
Hard grade ethylene propylene rubber (HEPR) 85 240 2.4 2.0
Halogen free hard grade ethylene propylene rubber 85 300 2.4 2.0
(HF HEPR) — For smaller cross sections than 1.5 mm2, the insulation thickness shall
not be less than specified for 1.5 mm2.
Cross linked polyethylene (XLPE) 85 — Table D2 is according to IEC 60092-3 for 0,15/0,25 kV cables and IEC
Halogen free cross linked polyethylene 85 60092-353 for 0.6/1.0 kV and 1.8/3 kV cables.
(HF XLPE)
Halogen free cross linked polyolefin (HF 85) 85 D 200 Protective sheaths
Silicone rubber, (S 95). 95 201 General
Halogen free silicone rubber (HF S 95). 95
a) All cables shall have a protective sheath over the core in-
b) Electrical and mechanical characteristics shall comply sulation, except for "switchboard wires" according to 400
with the specifications of table II, III and IV respectively (see also Sec.10 C700 regarding the installation of such
of IEC 60092-351. wires in pipes).
102 Minimum thickness of insulating walls b) The minimum average thickness of insulating walls given
in Table D2 applies. For other standard cross sections, in-
The minimum average thickness of insulating walls shall be termediate values may be used (for 60 V communication
used in accordance with Table D2. cables, see F, and for 250 V control cables, see E).
Table D2 Minimum average thickness of insulating walls c) Mechanical and particular characteristics of sheath mate-
rials shall comply with the specifications of table II and III
respectively of IEC 60092-359.
Nominal cross PVC/A EPR XLPE d) Thickness of sheaths is to comply with sub-clause 13.2 of
section of con- (mm) (mm) (mm)
ductor (mm2) IEC 60092-353.
Rated voltage 0.15/0.25 kV
e) Sheath materials shall be such that the cables are at least
1.5 0.7 0.8 0.7 flame retardant according to IEC 60332-1. (For cable
2.5 0.8 0.8 0.7 bunches, see Sec.10 C404.)
4 0.8 0.9 0.7
6 0.8 0.9 0.7
202 Temperature classes for protective sheaths
PVC/A EPR XLPE The temperature classes and materials shall be used in accord-
Nominal cross
HF EPR HF XLPE ance with Table D3.
(mm) S 95 HF 85
section of con- HEPR
ductor (mm2) Table D3 Temperature classes for protective sheaths
(mm) HF HEPR
(mm) Material Temperature
(°C)
Rated voltage 0.6/1.0 kV
Thermoplastic based on polyvinylchloride or copol- 60
1.5 0.8 1.0 0.7 ymer of vinylchloride and vinylacetate, type ST 1
2.5 0.8 1.0 0.7
4 1.0 1.0 0.7 Thermoplastic: 85
6 1.0 1.0 0.7 based on polyvinylchloride or copolymer of vi-
10 1.0 1.0 0.7 nylchloride and vinylacetate, type ST 2
16 1.0 1.0 0.7 Halogen free, type SHF1
25 1.2 1.2 0.9 Elastomeric or Thermosetting: 85
35 1.2 1.2 0.9
50 1.4 1.4 1.0 based on polychloroprene rubber, type SE 1
70 1.4 1.4 1.1 based on chlorosulphonated polyethylene or chlorin-
95 1.6 1.6 1.1 ated polyethylene rubber, type SH
120 1.6 1.6 1.2 Halogen free, type SHF2
DET NORSKE VERITAS

D 300 Wire braid and armour E. Control Cables

301 General E 100 Construction
a) Cables designated as copper, copper alloy, aluminium al- 101 General
loy or galvanised steel wire braided shall comply with a) Conductors shall have a cross section of 1.0 mm² and shall
clause 14 of IEC 60092-353. consist of plain or metal coated annealed copper of the cat-
b) Braid and/or armour shall be separated from the core insu- egory "circular non-compacted".
lation by an inner non-metallic sheath, by tape or fibrous b) Characteristics of the insulation shall be as specified in
braid or roving. D100.
c) Irrespective of the metal used, the nominal diameter of the c) The minimum average thickness of the insulation shall be
as specified in sub-clause 4.2 of the IEC 60092-376.
braid wire shall be in accordance with Table D4.
d) For protective sheath materials, the requirements in D200
Table D4 Nominal diameter of braided wire apply. The minimum sheath thickness is specified in sub-
Diameter of core assembly un- Minimum diameter of threads in clause 8.2 of IEC 60092-376.
der braid 1) braid 2) e) For metal wire braid and armour, the requirements of
(mm) (mm) D300 apply. Alternatively, the dimensions of metal braid
D ≤ 10 0.2 armour may instead comply with clause 9 of IEC 60092-
10 < D < 30 0.3 376.
D ≥ 30 0.4 Guidance note:
1) Diameter under braid is fictitious and calculated by the method of IEC If it is found necessary to provide cables with a screen in order to
60092-350 Appendix A.
reduce electromagnetic noise and interference, then this should
2) The "coverage density" of the braid shall be in accordance with sub- be in the form of a copper wire braid, or another equivalent effec-
clause 7.2 of IEC 60092-350. tive screening.
D 400 Switchboard wires ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
401 General
a) Switchboard wires may be single core wires without fur-

F. Instrumentation and Communication Cables
ther protection, complying with the specifications for in-
sulating materials in 101. F 100 General
b) The insulation on switchboard wires shall be at least flame 101 General
retardant according to IEC 60332-1. Insulation material
a) Conductors shall have a minimum cross section of 0.5
shall be one of the following: PVC, HEPR, HFHEPR, mm2, and shall be stranded. This requirement does not ap-
XLPE, HFXLPE or HF85. ply to internal wiring in consoles and control boxes.
c) Single core conductors may also be used for installation in b) Twisted pair data cables (as IBM Cat 5) 0.22 mm2 can be
closed piping system in accommodation spaces, when the accepted under the assumption that the strands of the
system voltage is a maximum of 250 V, and for control whole cable are kept as part of the termination, as for co-
wiring installed in closed piping system on machinery axial cables.
components. c) Characteristics of insulation materials shall be as specified
for low voltage cables in D100 and D200.
D 500 Lightweight electrical cables d) The minimum average thickness of the insulation shall be
501 General as specified in clause 13 and tables II and III of the IEC
60092- 375.
For high speed, light craft and naval surface craft cables ap-
e) For protective sheath material the requirements in D400
proved in accordance with the DNV type approval programme apply. For minimum sheath thickness as specified in
"Standards for Certification No. 2.9, Type Approval Pro- clause 13, tables II and III of IEC 60092-375 apply.
gramme No. 6-827.11-1: Lightweight Electrical Cables for
f) For metal wire braid and armour same requirements as for
High Speed, Light Craft and Naval Surface Craft", are accept- low voltage cables in D300 apply. Dimensions of copper
ed. wire braid as specified in the tables II and III of IEC
DET NORSKE VERITAS

SECTION 10
INSTALLATION
A. General Requirements by safe location or by additional protection, if not of a rug-

ged metallic construction.
A 100 General g) See Sec.2 I for additional requirements for vessel arrange-
101 General ment.
Reference is made to other sections of this chapter, especially 102 Ventilation of spaces with electrical equipment
Sec.2 for requirements affecting location, arrangements, and
installation of systems in an early project stage, and Sec.3 to The ventilation shall be so arranged that water or condensation
Sec.9 for requirements affecting the various equipment. from the ventilator outlets does not reach any unprotected elec-
trical equipment. See also Sec.2 I101.
Equipment in hazardous areas shall be selected, located and in-
stalled according to Sec.11. 103 High voltage switchgear and controlgear assemblies
102 References to standards Access to high voltage switchgear rooms and transformer
rooms shall only be possible to instructed personnel.
The requirements in this section are based upon IMO codes Guidance note:
and regulations and the relevant IEC standards.
Equipment located in machinery spaces may be considered as be-
ing accessible only to instructed personnel. The same applies to
equipment located in other compartments that are usually kept
locked, under the responsibility of the ship's officers.
B. Equipment
B 100 Equipment location and arrangement
104 Passage in front or behind switchgear
101 General
The passageways in front of and behind main and emergency
a) All electrical equipment shall be installed "electrically switchboards shall be covered by mats or gratings of oi resist-
safe". This is to prevent injury to personnel, when the ant insulating material, when the deck is made of a conducting
equipment is handled or touched in the normal manner. material.
b) All electrical equipment shall be selected and installed so 105 Transformers
as to avoid EMC problems. Thus preventing disturbing Liquid immersed transformers shall be installed in an area or
emissions from equipment, or preventing equipment from space with provisions for complete containment and drainage
becoming disturbed and affecting its intended function(s). of liquid leakage.
c) Electrical equipment shall be placed in accessible loca- 106 Heating and cooking appliances
tions so that those parts, which require manual operation,
are easily accessible. a) All combustible materials close to heating and cooking ap-
pliances shall be protected by incombustible or insulating
d) Heat dissipating electrical equipment as for example light- materials.
ing fittings and heating elements, shall be located and in-
stalled so that high temperature equipment parts do not b) Cabling and wiring (feeding) shall be suitable for the
damage associated cables and wiring, or affect surround- eventual higher temperature in the termination room of
ing material or equipment, and thus become a fire hazard. such equipment.
e) Semi-conductor converters stacks or equipment shall be c) Additional protection of IR–type of open heating elements
installed in such a manner that the circulation of air to and shall be installed, if necessary to guard against fire and ac-
from the stacks, associated equipment or enclosures is not cidental touching.
obstructed. The temperature of the cooling inlet air to con-
verter shall not exceed the ambient temperature for which B 200 Equipment enclosure, Ingress Protection
the stacks are specified. 201 Enclosure types in relation to location
f) All equipment of smaller type (luminaires, socket outlets Equipment enclosures shall comply with Table B1 in relation
etc) shall be protected against mechanical damage either to the location of where it is installed.
DET NORSKE VERITAS

Table B1 Enclosure types in relation to location

Location Switchgear Luminaires Rotating Heating ap- Socket Miscellaneous Instrumenta-
and trans- machines pliances outlets such as switches tion compo-
formers and connection nents
boxes
Above the floor IP 22 IP 22 IP 22 IP 22 IP 44 IP 44 IP 44
Below the floor N IP 44 IP 44 IP 44 N IP 44 IP 56
Dry control rooms
Engine and and switchboard IP 21 1) IP 22 IP 22 IP 22 IP 22 IP 22 IP 22
boiler rooms rooms
Closed compart-
ments for fuel oil IP 44 IP 44 IP 44 IP 44 N IP 44 IP 44
and lubrication oil
separators
Fuel oil tanks 2) N N N N N N IP 68
Ballast and other water tanks, bilge N N IP 68 IP 68 N N IP 68
wells 2)
Ventilation ducts N N 13) IP 4413) N N N 13)
Deckhouses, forecastle spaces,

steering gear compartments and IP 22 3) IP 22 IP 22 3) IP 22 IP 44 IP 44 IP44
similar spaces
Ballast pump rooms and similar IP 44 14) IP 44 IP 44 14) IP 44 IP 56 5) IP 56 5) IP 56 5)
rooms below the load line
Cargo holds 4) N IP 55 IP 44 N IP 56 5) IP 56 5) IP 56 5)
Open deck, keel ducts IP 56 IP 55 IP 56 6) IP 56 IP 56 5) IP 56 5) IP 56
Battery rooms, paint stores, gas
bottle stores or areas that may be N EX 12) EX 12) EX 12) N EX 12) EX 12)
hazardous due to the cargo or proc-
esses onboard 7)
Dry accommodation spaces IP 20 IP 20 IP 20 IP 20 IP 20 IP 20 8) IP 22
Bath rooms and showers N IP 44 11) N IP 44 N 9) IP 56 11) IP 56 11)
Galleys, laundries and similar IP 44 IP 44 IP 44 IP 44 IP 44 IP 44 IP 44
rooms 10)
(N: Normally, not accepted for installation in this location.)
1) Switchboards in dry control rooms and switchboard rooms with IP 21 shall have a roof with eaves. If there is a chance of dripping water from piping,
condensed water, etc. then a higher IP rating may be necessary.
2) For cable pipes and ducts through fuel oil and water tanks, see C703.
3) Such equipment shall be provided with heating elements for keeping it dry when not in use. The heating elements shall normally be automatically switched
on when the equipment is switched off. Continuously connected heating elements may be accepted provided the maximum allowed temperatures are main-
tained when the equipment is in operation.
4) For enclosures in cargo holds, placed so that they are liable to come into contact with the cargo or cargo handling gear, see 101. For truck battery charging
arrangements, see Sec.2 I305. For electrical installations in cargo holds for dangerous goods, see the Rules for Classification of Ships, Pt.5 Ch.11 Sec.2
B300. For special category spaces in passenger vessels and ferries see the Rules for Classification of Ships, Pt.5 Ch.2 Sec.2 F. For such cargoes, also
national regulations apply. For vessels carrying cars with fuel in their tanks see the Rules for Classification of Ships, Pt.4 Ch.10.
5) IP 44 may be accepted, when placed in a box giving additional protection against ingress of water. Equipment for control and indication of watertight
doors and hatches shall have watertightness based on the water pressure that may occur at the location of the component, if intrusion of water can affect
the control or indication system.
6) Motors on open deck shall have ingress protection IP 56, and either:
— be naturally cooled, i.e. without external cooling fan

— be vertically mounted and equipped with an additional steel hat preventing ingress of water or snow into any external ventilator
— or be equipped with a signboard requiring that the motor shall only be used in port, and be provided with additional covers (e.g. tarpaulins) at sea.
7) For arrangement and connection of batteries, see Sec.2. For installations in paint stores, gas bottle stores or areas that may be hazardous due to the cargo
or processes onboard, the requirements in Sec.11 shall be complied with.
8) Connection boxes may be accepted installed behind panels in dry accommodation spaces provided that they are accessible through a hinged panel or sim-
ilar arrangement.
9) Socket outlets shall be so placed that they are not exposed to splash, e.g. from showers. Circuits for socket outlets in bathrooms shall either be fed from a
double insulated transformer, or be equipped with earth fault protection with a maximum release current of 30 mA.
10) Stoves, ovens and similar equipment may be accepted with IP 22 when additionally protected against water splash by hose or washing of the floor.
11) Lower degree of protection may be accepted provided the equipment is not exposed to water splash.
12) Type of ingress protection shall be as for deckhouses. Minimum explosion group and temperature class shall be one of those specified in Table B2 (Some
national regulations may limit the choice of type of protection).
13) Luminaires and instrumentation components may be accepted after special consideration. It shall be observed that a ventilation duct may be a hazardous
area, depending upon the area classification at the ends of the duct.
14) Electric motors and starting transformers for side thrusters shall be equipped with heating elements for standstill heating.
DET NORSKE VERITAS

Table B2 Minimum explosion groups and temperature classes e) Metal enclosures or other exposed conductive parts being
for different locations a part of electrical equipment shall be earthed by fixing the
metal enclosure or exposed parts in firm (conductive) con-
Location Explosion group Temperature
class tact to the hull (main earth potential) or by a separate earth
conductor.
Battery rooms II C T1
Stores for welding gas bottles II C T2 f) For distribution systems with neutral earthed through an
Lamp rooms and paint stores II B T3 impedance or direct terminated and distributed neutral
(TN-S), protective earthing (PE) shall be carried out by
B 300 Batteries connecting exposed parts direct to feeding switchboard
main PE, via an earth conductor in the supply cable.
301 General
Battery installations are to comply with the requirements in g) Portable equipment shall always be earthed by an earth
Sec.2 I regarding requirements for their location, compart- conductor contained in the flexible supply cable.
ments etc. h) All extraneous conductive parts supporting electrical
302 Materials equipment and cable support systems, that is ladders, pipes
and ducts for electrical cables, are considered to be in firm
The following requirements apply to all stationary accumula- electrical contact with the hull as long as elements are
tor batteries: welded or mechanically attached (metal to metal without
a) Battery stands, boxes and lockers shall be fixed to the ves- paint or coating) with a star washer, thereby ensuring a
sel's structure. The batteries shall be fixed or supported on firm conductive contact. If firm electrical contact is not
the shelves. Shelves and fixings shall be constructed to achieved, the parts shall be bonded by a separate copper
withstand the forces imparted from the batteries, during conductor between extraneous parts and the hull.
heavy sea. i) Additional precautions shall be applied regarding earthing
b) All materials used for the construction, including ventila- of portable electrical equipment for use in confined or ex-
tion ducts and fans, shall be corrosion resistant or shall be ceptionally damp spaces where particular risks due to ex-
protected against corrosion by suitable painting, with con- posure and conductivity may exist.
sideration given to the type of electrolyte actually used. j) High voltage metal enclosures and the steel hull shall be
c) The materials shall be at least flame retardant, except that connected by a separate earth conductor. The enclosures
impregnated wood can be used for the support of battery fixing device shall not be the sole earthing connection of
cells, and for battery boxes on deck. the enclosure.
d) Except when corrosion resistant materials are used, the k) If a separate earthing conductor is chosen for equipment,
shelves in battery rooms and lockers and the bottom of bat- then the connection of the separate earth conductor to the
tery boxes shall be covered with a lining of corrosion re- hull, (safe earth potential) shall be made in an accessible
sistant material, having a minimum thickness of 1.5 mm position. The conductor shall be terminated by a pressure
and being carried up not less than 75 mm on all sides (e.g. type cable lug onto a corrosion protected bolt, which shall
lead sheath for lead and acid batteries, steel for alkaline be secured against loosening. Other suitable terminating
batteries). If the shelves in battery rooms and lockers are systems for direct receipt of the conductor may be consid-
of corrosion resistant materials and the floor is not, either ered.
the shelves or the floor shall be covered with such lining.
Guidance note:
303 Testing
Additional precautions in k) might be: The equipment having ex-
The following tests and inspections shall be performed before tra safe low voltage, or for ordinary 230 V equipment, by using a
batteries are put into service: safety transformer system or by having an earth fault switch of
maximum 30 mA in front of the circuit.
— ventilation shall be verified, including natural ventilation
— capacity tests, voltage measurements ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
— alarms and monitoring functions.
402 Exceptions to the earthing or bonding requirements
304 Marking and signboards
See 503 for the requirements for marking and signboards, with a) If one of the following conditions is fulfilled, the require-
respect to battery installations. ments in 401 above may be omitted:
B 400 Protective earthing and bonding of equipment — equipment supplied at a voltage not exceeding 50 V
D.C. or A.C. between conductors. Auto-transformers
401 General shall not be used for the purpose of achieving this
a) Earth conductors shall normally be of copper. However, voltage
other suitable materials may be accepted if, for example — equipment supplied at a voltage not exceeding 250 V
the atmosphere is corrosive to copper. by safety isolating transformer and the transformer is
supplying only one consumer device
b) The earth conductor's cross section shall be equivalent to
that of copper with regard to conductivity. Applicable ar- — equipment constructed in accordance with the princi-
rangements and cross sections are given in Sec.2 Table J2. ple of double insulation.
c) The connection to the hull of earth conductors or equip- b) Parts fixed to non-conductive materials, and separated
ment enclosure parts, which shall be earthed, shall be from current carrying parts and from earthed parts in such
made by corrosion resistant screws or clamps, with cross a way that they cannot become live under normal or elec-
section corresponding to the required cross section of earth trical fault conditions.
given in Sec.2 J303.
c) Bearing housings which are insulated in order to prevent
d) Earthing screws and clamps shall not be used for other circulating currents.
purposes. Suitable star washers and conductor terminals
shall be used, so that a reliable contact is ensured. d) Cable clips do not need protective earthing.
DET NORSKE VERITAS

403 Dimension of protective earth and bonding conductors C. Cables

For dimension of protective earth and bonding conductors, see
Sec.2. C 100 General
101 General
B 500 Equipment termination, disconnection, marking
501 General a) Cable sizing with respect to current carrying capacity and
short circuit withstand capabilities shall comply with the
All equipment shall be installed and terminated in accordance requirements in Sec.2.
with manufacturer's instructions to ensure that correct func-
tions and safe properties are contained. b) For requirements for cable construction and materials, see
Sec.9.
502 Multipole disconnection of equipment circuits
c) A.C. wiring shall be carried out, as far as practicable, in
a) All electric circuits connecting final consumers shall be twin or multicore cables.
provided with multipole disconnection device. d) For installations in connection with hazardous areas, re-
b) The multipole device shall be an on load switching device. quirements for selection of cables, cable routing and fix-
MCBs with accessible on and off levers, intended for load ing, see Sec.11.
switching, may be accepted. Guidance note:
c) All consumers other than motors shall be controlled by at Use of cables with low emission of smoke in case of a fire, should
least a multipole switchgear, except that single pole be considered for all indoor installations. In areas where equip-
switches can be used for luminaires or space heaters in dry ment sensitive to corrosion is installed or kept, use of Halogen
accommodation spaces where floor covering, bulkhead free cables should be considered to avoid corrosive smoke in case
and ceiling linings are of insulating material. of a fire, as far as is practicable.
Guidance note:
Multipole disconnection means that all active poles are discon- 102 Painting of cables
nected simultaneously. However, any N-conductor is not regard-
ed as an active pole, and need not be disconnected. Electrical cables may be coated or painted, but this shall not
adversely affect the mechanical, chemical or fire resistant
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- characteristics of the sheath.
503 Signboards for equipment Guidance note:
The Society has experience from cables damaged by two compo-
a) Labels (nameplates) of flame retardant material, bearing nent epoxy painting bonding to the sheath material.
clear and indelible indications, shall be so placed that all Unless the yard has experience with the combination of paint and
equipment necessary for the operation can be easily iden- cable type used, the manufacturers should be consulted by the
tified. All labels shall be permanently fixed. yard.
b) All equipment shall, if necessary, be marked so as to en- ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
sure correct use. Signboards giving guidance for safe use,
or conditions for use, shall be fitted, if necessary, in order 103 Cable sheath
to avoid inadvertent or dangerous operation of equipment Cables with metal sheath or braid or armour shall be provided
and or systems. with an outer sheath for corrosion protection when installed on
c) "High voltage" warning signboards are required on all deck, through cargo holds, in pump rooms, keel ducts and sim-
high voltage equipment. ilar wet or corrosive spaces. This also applies to cables carried
in pipes in such spaces, and to cables that are carried in pipes
d) High voltage cables shall be suitably marked with "high through water or fuel oil tanks.
voltage" warning signboards, at least for every 20 m, so
that a signboard is always visible. Guidance note:
Any additional armour provided, but not required by the rules,
e) On rotating machines, on deck, that are not naturally does not need a protective outer sheath as long as the protective
cooled, i.e. with external cooling fan, a signboard shall be armour is not used as a conductor for protective earthing.
fitted on the machines requiring that the machines shall
only be used in port and be provided with additional cov- ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
ers (e.g. tarpaulins) when at sea.
104 Corrosion protection
f) At each socket outlet for portable appliances where 1000
V is accepted, (e.g. welding transformers, refrigerated Sheath or braid or armour of lead, bronze or copper shall not
containers etc., which are not hand-held during operation) be installed in contact with aluminium alloy structures, except
an additional warning sign shall be fitted, with the text: in dry accommodation spaces.
DANGER (maximum voltage) V A.C. ONLY FOR CON- 105 Flexible cables
NECTION OF ....(type of equipment)....
The use of flexible cables shall be limited to applications
g) Signboards shall be fitted in battery rooms and on doors or where flexibility is necessary, and the lengths of such flexible
covers of boxes or lockers, warning against risk for explo- cables shall be kept as short as practicable. Special require-
sive gas, smoking and the use of naked lights. ments may be made to the type, installation and protection of
h) All batteries shall be provided with labels (nameplates) of flexible cables, depending upon the application.
flame retardant material, giving information on the appli- 106 High voltage cables
cation for which the battery is intended, make, type, volt- Installation of high voltage cables in accommodation spaces is
age and capacity. Instructions shall be fitted either at the not permitted unless required by the application. The necessity
battery or at the charging device, giving information on for special protection shall be evaluated when high voltage ca-
maintenance and charging. bles are installed in accommodation spaces, for prevention of
i) Battery systems above 50 V shall be marked with special harmful effects to personnel from cable short circuits, and
visible warning signboard, i.e. “Warning xxx voltage”. strong electromagnetic fields.
DET NORSKE VERITAS

107 Fibre optic cables 205 Accessible cable runs

Tensile stress applied to fibre optic cables for any reason dur- a) Cable runs shall be accessible, except for cables carried in
ing the installation period or during normal operation shall not pipes.
exceed the maximum allowed value stated by the manufactur-
er. b) Cable runs shall be accessible for later inspection. Free
distance above trays, and cables laid on trays, shall be a
C 200 Routing of cables minimum of 100 mm. Distance between cable trays, or to-
wards adjacent structures shall be a minimum of 50 mm.
201 General c) When cable runs are carried behind wall lining in accom-
For more requirements regarding the routing of cables, see modation spaces (except when carried in pipes), the panels
Sec.2 I400. shall be hinged or fixed for example by screws, so that
they can be removed for inspection without damaging the
202 Segregation of low and high voltage cables cable or the bulkhead.
a) Low voltage power cables shall not be bunched together d) Exceptions can be made for cables to light fittings, switch-
with, or run through the same pipes as, or be terminated in es, socket outlets etc. in dry accommodation spaces, when
the same box as, cables for high voltage. the deckhead and bulkhead constructions are made of in-
combustible materials.
b) High voltage cables shall be separated from low voltage
cables and control cables by at least 300 mm unless me- C 300 Penetrations of bulkhead and decks
chanically separated by earthed metal partitions or pipes. 301 General
203 Segregation of power cables and cables for control cir- a) Penetrations of watertight bulkheads and decks shall be
cuits carried out either with a separate gland for each cable, or
with boxes or pipes filled with a suitable flame retardant
a) Unscreened cables for sensitive control or signal circuits packing or moulded material, in order to ensure the integ-
(below 50 V) shall not be run in the same bunch or pipe as rity of the watertightness of the bulkhead or deck. The in-
cables for power circuits, (above 50 V). This is in order to stallation shall be in accordance with the manufacturers'
avoid interference from the power circuit. installation instructions.
b) For segregation of cables in installations for hazardous ar- b) Penetrations of a recognised make shall be used where fire
eas, see Sec.11 D200. resisting separation is needed.
Guidance note: Guidance note:

Penetrations of watertight bulkheads should be placed as high as
Crossovers or installation of power cables and control cables be- practicable.
side each other are generally not considered a problem if signal
cable is screened. ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
A distance of 50 mm between power and unbraided or un-
screened control cables on a cable tray is considered acceptable. 302 Thermal insulation
Cable runs shall not be laid in or covered with thermal insula-
tion (e.g. through refrigerated cargo holds), but may cross
through such insulation.
204 Special precautions for single core cables
303 Hot oil pipes near to penetrations
When the use of single core cables is necessary for circuits
having a normal current of 20 A and above the following ap- The distance from cable penetrations to flanges of steam or hot
ply: oil pipes shall not be less than 300 mm for steam or hot oil
pipes with diameter D ≤ 75 mm, and not less than 450 mm for
a) The cables shall be non- armoured or braided or the ar- larger pipes.
mour or braiding material shall be of a non-magnetic type. 304 Chafing
b) The non-magnetic armour or braiding shall be earthed at Penetrations of bulkheads and decks shall be such that the ca-
one end, only. bles are not chafed.
c) Conductors belonging to the same circuit shall be con- 305 Mechanical support of penetrations
tained within the same pipe, conduit or trunking, clamps The cable shall have mechanical fixing on both sides of a bulk-
that fix them shall include all phases. head penetration.
d) The phases shall be laid as close as possible and preferably C 400 Fire protection measures
in a triangular formation.
401 General
e) Magnetic material shall not be used between single core
cables for one consumer. All phases belonging to the same The cable installation shall be protected against fire, fire
circuit shall be run together in a common gland or bulk- spreading, thermal, mechanical, corrosive and strain damage.
head penetration (MCT), unless the penetration system is 402 Flammable materials
of non-magnetic material. Unless installed in a triangular Cables shall not be installed in contact with flammable materi-
formation, the distance between the cables and magnetic als such as wooden bulkheads, when the conductor tempera-
material shall be 75 mm. ture exceeds 95°C at full load, at the actual ambient
f) Circuits with several single core cables for each phase temperature.
(forming groups) shall follow the same route and have the 403 Precautions against fire spreading in cable bunches
same cross sectional area.
Cables that are installed in bunches shall have been tested in
g) The cables belonging to the same phase shall as far as accordance with a recognised fire test for cables installed in
practicable alternate with those of the other phases, so that bunches, such as the test specified in IEC 60332-3, or be pro-
an unequal division of current is avoided. vided with protection according to 404 and 405.
DET NORSKE VERITAS

Guidance note: 503 Mechanical protection of cables and cable runs

A cable bunch is defined as five or more cables laid close togeth-
er in trunks from machinery spaces and in spaces with a high risk a) Cables shall be so installed that they are not likely to suffer
of fire, and more than 10 cables in other areas. mechanical damage. If necessary, they shall be protected
by providing the cable runs with covers of plates, profiles
or grids, or by carrying the cables in pipes.
404 Cable bunches not complying with IEC 60332-3 or other b) Below the floor in engine and boiler rooms and similar
recognised standard fire spread test. spaces, cables that may be exposed to mechanical damage
during maintenance work in the space, shall be protected
a) Cable bunches, not complying with flame retardant prop- in accordance with a).
erties according to IEC 60332-3, shall be provided with
fire stops having at least class B-0 penetration properties c) On weather decks in cargo hold areas, and through cargo
at the following locations: holds, all cables that may be exposed to mechanical dam-
age, shall be protected by covers of steel plates, steel grids
— cable entries at the main and emergency switchboards or profiles of at least 4 mm thickness, or by being carried
— where cables enter engine control rooms in steel pipes.
— cable entries at centralised control panels for propul- Guidance note:
sion machinery and essential auxiliaries
As an alternative the covers can be made of perforated steel
— at each end of totally enclosed cable trunks plates or grids with mesh opening maximum 25 mm, having at
— at every second deck or approximately every 6 m for least the same impact strength as a 4 mm steel plate. Exemptions
vertical runs can be accepted when the location of the cable run is such that in
— at every 14 m for horizontal runs, except that in the all probability cargo or cargo handling gear cannot come into
cargo area fire stops need only be fitted at the bound- contact with the cable run. When cable runs are fixed to alumin-
aries of the space. ium structures, aluminium may be used instead of steel.
Additional fire stops need not be fitted inside totally en-
closed cable trunks. 504 Cable bends
b) Alternatively, for additional fire stops, fire protective coat-
ing may be applied to the cable bunch according to the fol- a) The internal radius of low voltage cable bends, which are
lowing: not subjected to movement by expansion, shall be in ac-
cordance with the manufacturers' recommendation, but
— to the entire length of vertical runs normally, not less than given in Table C2.
— to at least 1 m in every 14 m for horizontal runs. b) The minimum internal bending radius for high voltage ca-
bles shall be in accordance with the manufacturers' recom-
405 Fire resistance of penetrations mendations.
Where "A" or "B" class bulkheads or decks are penetrated for
the passage of electrical cables, arrangements shall be made to Table C2 Cable bending radii
ensure that the fire resistance of the bulkheads or decks, is not Cable construction Overall di- Minimum
impaired. ameter of internal ra-
Insulation Outer covering
cable (D) dius of bend
C 500 Support and fixing of cables and cable runs Unarmoured or un- ≤ 25 mm 4D
braided > 25 mm 6D
501 General
Metal braid
a) Cable ladders, trays and cable pipes shall not be used for screened or ar- Any 6D
carrying water, oil or steam pipes. Exemptions may be moured
considered in each case. Thermoplastic or Metal wire ar-
thermosetting moured
b) For installations in connection with hazardous areas, re- with circular Metal tape ar- Any 6D
quirements for selection of cables, cable routing and fix- copper conduc- moured or metal
ing, see Sec.11. tors sheathed
Composite polyes-
502 Cable ladder or tray material and mechanical require- ter or metal lami-
ments nate tape screened Any 8D
units or collective
a) Cable ladders and trays with their fixing devices shall be tape screening
made of corrosion resistant steel or type tested non-metal- Thermoplastic or
lic materials with equal properties. thermosetting
b) When fixed to aluminium structures, aluminium alloy ca- with sector Any Any 8D
shaped copper
ble ladders and trays may be used. Other materials may be conductors
accepted upon special consideration.
c) Cables with IEC 60228 Class 5 conductors shall be in- 505 Fixing of cables
stalled on continuous cable trays (vented or non-vented)
such as to prevent undue sag, and if horizontal, on the top a) Cables shall be fixed by clips, saddles or bands, of corro-
of the tray giving support to the cable. sion resistant metal, except when carried in pipes.
b) The spacing between supports or fixing shall be suitably
Guidance note: chosen according to the type of cable and the probability
The term "cable ladder" includes support brackets. The term "ca- of vessel movement and vibration at the actual point of in-
ble tray" means constructions being formed by continuous tray stallation, as given in Table C3.
plates or structural steel.
c) Cables shall be supported so close to an enclosure entry
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- through a cable gland that it runs straight through the
DET NORSKE VERITAS

gland, and the gland does not take up any mechanical forc- 602 Cables across expansion joints
es from the cable.
a) The installation of electric cables across expansion joints
d) When cables are installed on horizontal ladders or trays, in any structure shall be avoided. Where this is not practi-
the fixing distance may be 3 times larger than given in Ta- cable, a loop of electric cable of length sufficient to ac-
ble C3. However, when cable runs are subjected to water commodate the expansion of the joint shall be provided.
splashing on weather decks the maximum distance be- The internal radius of the loop shall be at least 12 times the
tween fixings of cable and its support (cable trays or pipes) external diameter of the cable.
shall be 500 mm.
b) All cables shall be fastened on each side of an expansion
e) When cable runs are installed directly on aluminium struc- loop, such that all relative movement between structure
tures, fixing devices of aluminium shall be used. For min- and cable is taken up at this point, and not in the rest of the
eral insulated cables with copper sheath, fixing devices in cable run.
metallic contact with the sheath shall be of copper alloy.
603 Cable trays along main decks
f) When cables tested in accordance with IEC 60092-332-3
are installed vertically, the fixing distance shall be in ac- a) Cable trays or pipes run in the length of the vessel shall be
cordance with the test requirements. However, the fixing divided into a number of sections each rigidly fixed to the
distance shall not be more than 407 ±10 mm. deck at one point only and sliding supports for the rest of
the section.
Table C3 Spacing of fixing points for cables
b) The expansion and compression possibility shall ensure
External diameter of cables Non-armoured Armouredor
or unbraided braided ca- that the cables do not become fully stretched during oper-
Exceeding Not exceeding ation. The expansion and compression possibility shall be
(mm) (mm) cables (mm) bles (mm)
at least ±10 mm for every 10 m section length from the fix-
- 8 200 250 ing point.
8 13 250 300 c) The cables shall be fixed to the tray as required by 500, and
13 20 300 350 at each expansion and compression point, the cable shall
20 30 350 400 have adequate room for bending and stretching.
30 - 400 450 d) When pulled in pipes, the cable shall be fixed to the pipe
at both ends of each section. Each pipe section shall be in-
506 Fixing in accommodation stalled without the possibility for expansion within the
In accommodation spaces, clips, saddles and bands of a non- section.
metallic, flame retardant material may be used for horizontal
runs. Guidance note:
When pipes are joined by the use of expansion joints, the pipe
507 Fixing in engine room or other areas of heat and light ends will not satisfy the above requirements.
radiation.
a) For installations in engine room and similar areas, metallic
cable clips or bands shall be used. C 700 Cable pipes
b) Flame retardant polymer material may be used for cable 701 Cable pipes
fixing (clips) if the material is resistant to heat and light ra-
diation, affecting the material during the lifetime of the a) Cables that are carried in the same pipe shall be of such
vessel. construction that they cannot cause damage to each other.
b) The pipes shall be suitably smooth on the interior and pro-
c) When cables are fixed on a tray by means of clips or straps tected against corrosion. The ends shall be shaped or
of non metallic material, and these cables are not laid on bushed in such a way that the cable covering is not dam-
top of horizontal cable trays or supports, metal cable clips aged.
or saddles shall be added at regular distances (e.g. 1 to 2
m) in order to retain the cable during a fire. c) Cables that are carried in pipes with length exceeding 10
m horizontally shall be bronze or steel wire braided or
508 Fixing of single core cables steel armoured to avoid damage when pulling in.
In order to guard against the effects of electrodynamic forces d) When cable pipes are installed vertically due attention
developing on the occurrence of a short circuit or earth fault, shall be paid to the cable's mechanical self carrying capac-
single core cables shall be firmly fixed, using supports of ity. For longer pipes, suitable installation methods shall be
strength adequate to withstand the dynamic forces correspond- used.
ing to the prospective fault current at that point of the installa- e) Cable pipes shall not include expansion elements required
tion. The fixing clamps of the cables should not damage the by 600.
cable when the forces affect the cables during a 1 s short circuit
period. 702 Cable pipe material
Guidance note: a) Cable pipes shall be made of steel or type tested non-me-
Manufacturer's instructions for installation with respect to pro- tallic materials.
spective fault current shall be followed.
b) The cable pipe material shall not have less resistance
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- against fire than required from the cable itself.
c) Aluminium cable pipes may be used if fixed to aluminium
C 600 Cable expansion structures.
601 Expansion of cable runs 703 Wall thickness of cable pipes
Cable runs and bulkhead penetrations shall be installed so that
they do not take up hull forces caused by the vessel's move- a) The following minimum wall thickness, d, applies:
ments, different load conditions and temperature variations. For D ≥ 160 mm: d = 4 mm
DET NORSKE VERITAS

D
For D < 160 mm: d = 1.5 + 1.56 --------- 802 Splicing in junction boxes
100
Where D is nominal internal diameter of pipe, and d is wall a) Junction boxes may be used for splicing of cables when
thickness. the following is complied with:
b) For use on deck and in water and fuel oil tanks, the mini- — the boxes shall be located in accessible places
mum wall thickness in Table C4 applies. — cables for main and emergency circuits shall not be
spliced in the same box
Table C4 Pipe wall thickness — cables for different systems and/or voltages shall be
Internal diameter of pipe 1) Minimum wall thickness clearly marked and separated.
(mm) (mm)
D ≤ 57.0 3.5 b) Junction boxes used for splicing shall be marked with volt-
57.0 < D ≤ 152.4 4.2 age level(s) and box identification.
152.4 < D 5.0 c) All conductors shall be connected in permanently fixed
1) For closed ducts of non-circular shape, the corresponding cross section terminals.
applies as criterion.
C 900 Termination of cables
704 Corrosion protection of cable pipes 901 Marking of cables
Steel cable pipes on deck, through cargo holds, in keel ducts,
pump rooms and similar wet spaces, and in water and fuel oil All terminals for connection of external instrumentation and
tanks shall be internally and externally galvanised, or shall control cables, as well as the conductor ends of these cables
have an equivalent effective corrosion protection. shall be clearly marked for identification, preferably in accord-
ance with the designation used in the wiring diagram.
705 Condensation in cable pipes
902 High voltage cables
Cable pipes with connection and draw boxes shall be arranged
so that condensed water is drained out of the system. High voltage cable shall have ending or termination kits ap-
proved or recommended from the cable manufacturer.
706 Bending radius of pipes
The termination kit shall be appropriate for the voltage level in
The bending radius of cable pipes shall be sufficiently large so question.
that "drawing-in" of the cables does not cause damage to the
cables, and in no case less than: 903 Cable entrance
Cable entrances in equipment shall at least have the same IP
— the minimum bending radius of the cables according to rating as the equipment itself in order to maintain the integrity
504 of the enclosure.
— twice the internal diameter of the pipe.
Guidance note:
707 Filling of cable pipes See Sec.11 for requirements for cable glands, with respect to
The sum of the cables' total cross section, based on the cables' equipment in hazardous areas.
external diameter, is not to exceed 40% of the pipe's internal ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
cross section. This does not apply to a single cable in a pipe.
708 Connection and draw boxes 904 Earthing of cable metal covering
a) Connection and draw boxes shall have at least the same a) All metal coverings (braiding or armour) of power cables
wall thickness as required for the pipes, and shall be of shall be electrically connected to the metal hull (earth) of
steel, with exemption for aluminium alloy pipes, where the vessel at both ends of the cable. Single point earthing
galvanised cast iron or aluminium alloy shall be used. is permitted for final sub circuits and in those installations
(such as for control or instrumentation) where it is re-
b) All connection and draw boxes shall be accessible (for quired for technical reasons.
boxes behind panels in accommodation spaces, see Table
B1, footnote 8). b) The electrical continuity of all metal coverings shall be en-
sured throughout the length of the cables, at joints, tap-
C 800 Splicing of cables pings and branching of circuits.
801 Splicing c) When metal coverings (braiding or armour) are earthed at
one end only, the floating end shall be properly insulated.
a) Splicing of cables by using a kit or system from a recog-
nised manufacturer is accepted. d) The braiding or armour shall be connected directly from
the cable to a dedicated earth terminal or bar, except for
b) The two cables spliced shall have the same basic construc- short circuit proof installation where the braiding shall be
tion. insulated with a crimp-on sleeve.
Guidance note: e) Single core cables for A.C. and special D.C. cables with a
Splicing is meant as the direct continuation of cable lengths and high ripple content (e.g. for thyristor equipment) shall be
not transfer into a distribution box. earthed at one end only.
The splicing kit should contain the following as minimum: f) The metal covering or braiding or armour of cables may be
earthed by means of glands intended for that purpose. The
— connectors for conductors, of correct size glands shall be firmly attached to, and in effective metal
— replacement insulation contact with the earthed enclosure, of equipment.
— replacement inner sheet or common covering
— connector for braiding or armour g) Special clamp-on connections for making the connection
— replacement outer sheath with minimum fire properties as from metal covering or armour or braiding, to the earth ter-
the original sheath minal might be accepted if being of a recognised type in-
— splicing instructions. tended for the purpose. Earth connection of metal covering
shall not be made by ordinary soldering or other untested
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- solutions.
DET NORSKE VERITAS

h) Screens around individual pairs for earthing for EMC pur- g) The trace cable system with feeder connection boxes, ther-
poses in cables for control, electronic, communication and mostats, etc shall be mounted to avoid or be protected
instrumentation equipment, shall normally be earthed at against mechanical damage.
one end only. Cables having both individual screen and h) Flexible conduits should be used as mechanical protection
common screen (or braiding) shall have these metal cover- for the feeder cable to the trace start junction box installed
ings separated from each other at the “floating” end, when on the pipe.
earthed at one end only.
i) Trace heating cables shall be installed in such a way as to
i) The connection of the earth conductor, to the parts that allow dismantling of joints and valves, instruments etc.
shall be earthed, and to the hull, shall be made by corrosion without cutting or damaging the cable. Trace heating ca-
resistant screws or clamps, with a cross section corre- bles shall be installed along the lower semi-circle of the
sponding to the earth conductor. Such earthing screws and pipes.
clamps shall not be used for other purposes. Suitable
washers and conductor terminals shall be used, so that a j) The outside of traced pipes thermal insulation or protec-
reliable contact is ensured. tive cladding shall be clearly marked at appropriate inter-
vals to indicate the presence of electric tracing of surface
Guidance note: heating equipment.
The requirement for earthing of the cable metal sheath, armour k) Trace circuits shall be readable marked (or identified) at
and braid, in 904 is not made with respect to earthing of equip- both the switchboard and the field end, for fault finding
ment or consumers, but for the earthing of the cable itself.
purposes.
Armour or braiding might be accepted as a PE- conductor for the
equipment itself if cross section is sufficient and the cable type is l) Circuits, which supply trace and surface heating, shall be
constructed for that purpose. provided with an earth fault circuit breaker. Normally the
For cables without an insulating sheath over the metal sheath or
trip current shall be 30 mA. Higher trip currents (maxi-
armour or braiding, the earthing of the cable itself may be carried mum 300 mA) for the circuit breaker will be accepted if 30
out by fixing the cable to the hull constructions, or to parts that mA is impossible, due to capacitive current leakage in the
are welded or riveted to the hull constructions, by corrosion re- trace cable circuit.
sistant clamps or metal clips.
For earthing of instrument and control circuits for guarding
against disturbances (EMC) see also DNV-OS-D202.
D. Inspection and Testing
D 100 General
905 Conductor ends (termination)
101 General
a) All conductor ends shall be provided with suitable pres- Before an installation is put into service or considered ready
sured sockets or ferrules, or cable lugs if appropriate, un- for operation, it shall be inspected and tested. The aim for this
less the construction of the terminal arrangement is such testing is to verify that the physical installation is correct. The
that all strands are being kept together and are securely installation shall be verified in accordance with relevant docu-
fixed without risk of the strands spreading when entering mentation. There shall be no hazard to personnel, no inherent
the terminals. fire hazard, and the installation shall function as required for
b) IEC 60228 Class 5 conductors shall be fitted with pres- the safe operation of the vessel.
sured ferrules as required by a).
D 200 Equipment installation
c) Termination of high voltage conductors shall be made by
using pressure based cable lugs unless the actual equip- 201 Location and ingress protection
ment has connection facilities for direct connection of the It shall be verified that all equipment is suitably installed with
stripped conductor tip. respect to ventilation, ingress protection and accessibility. (In-
gress Protection according to Table B1)
d) Spare cable conductors shall either be terminated or insu-
lated. For Ex installations, see Sec.11. 202 Escape routes
C 1000 Trace or surface heating installation require- Switchboards more than 7 m long shall not form dead end cor-
ments ridors. Two escape routes shall be available as required by
Sec.2 I103 e.
1001 General
D 300 Wiring and earthing
a) Heating cables, tapes, pads, etc. shall not be installed in 301 General
contact with woodwork or other combustible material. If
installed close to such materials, a separation by means of All equipment shall be verified with respect to proper installa-
a non-flammable material may be required. tion with respect to external wiring and protective earthing.
b) Heat tracing shall be installed following the system docu- 302 High voltage testing of cables
mentation from the manufacturer. After installation, with termination kit applied, high voltage
c) Serial resistance trace heating cables shall not be spliced. cables shall be subject to one of the following alternative high
voltage tests, with the voltage applied between the conductors
d) Trace heating cables shall be strapped to equipment and and the screen:
pipes using a heat resistant method that does not damage
the cable. i) A power frequency test voltage (A.C.) applied for 5 min-
e) Space between fixing points should be a maximum of 300 utes. With the designed rated power frequency voltage be-
mm. tween the phase and earth or screen given as U0, the test
voltage (A.C.) shall be:
f) Where practicable and where exposed to weather, the ca-
bles shall pass through the thermal insulation from below, — 0.7*(2.5 * U0 + 2) kV for cables with U0 not exceed-
via a gland to avoid mechanical damage to the trace cable. ing 3.6 kV
DET NORSKE VERITAS

— 0.7*2.5 * U0 kV for cables with U0 in excess of 3.6 402 Testing of electric distribution systems
kV.
a) Upon completion, the electric distribution system shall be
ii) A power frequency test at the normal operating voltage of subject to final tests at a sea trial.
the system, applied for 24 hours. b) The final test at sea assumes that satisfactory tests of main
components and associated subsystems have been carried
iii) A D.C. voltage of 1.7 times the value for the 5 minute out.
power frequency test voltage, applied for 15 minutes.
c) The test program is to include tests of the distribution in
Guidance note: normal conditions, and in any abnormal condition in
which the system is intended to operate.
The 5 minutes power frequency test is seldom used at the instal-
lation site due to the high reactive power needed for this method. d) Start-up and stop sequences shall be tested, together with
different operating modes. Also when controlled by auto-
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- matic control systems when relevant.
303 Insulation resistance testing of circuits and equipment e) Interlocks, alarms and indicators shall be tested.
f) All control modes shall be tested from all control loca-
All outgoing power circuits from switchboards (cables and tions.
consumers) connected during installation shall undergo insula-
tion resistance testing to verify its insulation level towards 403 Testing of generators and main switchboards
earth and between phases where applicable (i.e. switchboards All generating sets together with their switchboard equipment
assembled at site.) (switchgear or protection and cabling) shall be run at the rated
load for one hour, and tested to verify that the following are
The insulation resistance tests (megger tests) shall be carried within satisfactory limits:
out by means of a suitable instrument applying a D.C. voltage
according to Table D1. — electrical characteristics in general, including temperature
rise of insulation and control of the generator itself
Table D1 Insulation resistance test voltage — engine room ventilation
Un (A.C.) equipment D.C. megger voltage — voltage regulation (normal and transient conditions)
Up to 100 V 250 V — speed governing (normal and transient conditions)
— overspeed trips
100 to 250 V 500 V
— testing of overload protection
380 to 690 V 1000 V — other protection like: earth fault, differential, under or ov-
1 to 3 kV 2.5 kV ervoltage, frequency (if applicable)
3 to 15 kV 5 kV — synchronising systems (if any)
— load sharing
Guidance note: — reverse power protection.
The insulation resistance value obtained might vary due to cli-
matic conditions, length of cable circuits, power of megger, etc. The voltage and speed regulation under normal and transient
Therefore an exact value limit is sometimes difficult to state and conditions shall be within the limits given in Sec.2 A, Sec.2 E,
reasonable values obtained below the following limits might be Sec.5 B and the Rules for Classification of Ships Pt.4 Ch.3.
accepted. The average ohm-value obtained from insulation re- Guidance note:
sistance measurement shall in general be 1 MOhm between phas- Testing of overload and short circuit protection: Secondary cur-
es and earth for circuits operating at a voltage above 50 and up to rent injection is accepted as a method for verification of correct
400 V (minimum 0.3 MOhm below 50 V). operation. For moulded case circuit breakers, smaller MCBs with
integrated protection units, or ACBs with integrated protection
For circuits with nominal voltage above 400 V the minimum re- units (not wired up at site) tested at manufacturers, a verification
sistance should be: of protection settings is sufficient.
æ Nominal
----------------------------------------------ö + 1 MOhm
Voltage
è 1000 ø 404 Testing of voltage drop
Tests may be required to verify that the allowable voltage drop
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- is not exceeded.
405 Testing of current distribution
D 400 Distribution system properties Current distribution in parallel connected cables shall be veri-
401 Testing of consumers (cable end equipment) fied.
406 Testing of battery supplies
a) Function and load testing for essential and important
equipment. a) UPS systems and regular D.C. battery backed up power
supply (transitional, emergency or clean power) systems
b) Consumers for essential and important functions shall be serving essential or important functions shall be function
tested under normal operating conditions to ensure that tested for dip free voltage when feeding power is being
they are suitable and satisfactory for their purposes. switched off (black out simulation).
c) Setting of protective functions shall be verified. b) The battery backed up power supply system shall be run
on expected load (in battery feeding mode) for a period de-
d) Consumers having their protective function (overload, termined by the requirements for the actual system and by
short circuit and eventual earth fault protection) wired up the relevant rules This test is required in order to show the
during installation, shall be tested for correct function. See correct capacity of the systems.
also guidance note to 403. c) Alarms shall be verified for correct function.
DET NORSKE VERITAS

SECTION 11
HAZARDOUS AREAS INSTALLATIONS
A. General Guidance note:

The IP rating shall be listed so that correspondence with IP rating
A 100 General required according to the requirements in Sec.10 is demonstrat-
ed.
101 Reference to international standards, regulations and
definitions ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
a) The requirements in this section are based upon the fol-

lowing standards: IEC 60079 part 0 to, and including part
19 regarding equipment construction. IEC 61892 part 7
“Mobile and fixed offshore units; Hazardous areas”, IEC C. Equipment Selection
60092-502 “Special features-tankers”, and IMO MODU
Code, for equipment selection and installation require- C 100 General
ments. 101 General
b) For definitions related to installations in hazardous areas, For the selection of electrical equipment that shall be installed
see Sec.13 A600. in hazardous areas the following requirements apply:
a) The Ex protection type shall be in accordance with any re-
quirements for the area or zone in question, or as found in
B. Documentation any applicable additional class notation.
B 100 General b) Unless described in additional class notations, the hazard-
ous area shall be categorised into hazardous zones in ac-
101 General cordance with a relevant IEC standard, and the equipment
Electrical installations in hazardous areas shall be documented shall be acceptable in accordance with 200 for installation
to comply with these rules. in the hazardous zone category.
102 Compilation of documented data c) For installations covered by the rules for tankers for oil,
chemical carriers or liquefied gas carriers, the require-
For electrical installations in hazardous areas, the information ments in the Rules for Classification of Ships, Pt.5 Ch.3,
in Table B1 shall be compiled in a list or schedule of Ex-equip- Pt.5 Ch.4 or Pt.5 Ch.5 apply, with respect to what equip-
ment (see Sec.1 with respect to any formalities for a classed ment that may be installed in different areas and spaces.
vessel).
d) Electrical equipment and wiring shall not be installed in
Table B1 Schedule of information on installations in hazardous hazardous areas unless essential for operational purposes
areas
and when permitted by the relevant rules.
Information Description C 200 Ex protection according to zones
element
Identification Tag number or other reference used for mark- 201 Zone 0
ing of the specific equipment. This shall be
the same in the documentation as on the phys- a) Electrical equipment installed into zone 0 shall normally
ical installation be certified safe for intrinsic safety Ex-ia.
Equipment type Descriptive title of equipment, e.g. “cable b) For zone 0 systems, the associated apparatus (e.g. power
gland”, “fire detector” supply) and safety barriers shall be certified for Ex-ia ap-
Location of equip- The relevant location of the equipment, ac- plication.
ment cording to the hazardous area classification
drawing 202 Zone 1
Manufacturer Name and nationality of manufacturer
Type designation Manufacturers' type designation a) Electrical equipment installed into zone 1 shall be certified
Certification body, Identification of certifying body, the Ex cer- safe with respect to one of the following protection meth-
certificate number tificate number and type of Ex protection ods:
and type of protec-
tion — Ex-i (intrinsic safe) category a or b
Special conditions If the certificate number ends with “X” or — Ex-d (flameproof)
“U”, compliance with the special conditions — Ex-e (increased safety)
given in the certificate shall be stated — Ex-p (pressurised)
Is-circuit limits and For intrinsic safe circuits the maximum pa- — Ex-m (moulded)
values rameters and values contained in the circuit
with respect to voltage versus capacitance — Ex-s (special protection).
(Ceq) and current versus inductance (Leq)
shall be listed for each circuit. The maximum b) For Ex-i circuits, the associated apparatus, for example
values for the applied safety barrier shall be power supply and safety barriers shall be certified safe as
included well.
TE -time For motors and transformers located in a zone c) Normally, Ex-o (oil filled) and Ex-q (sand filled) are not
1, certified as “increased safe”, Ex-e, the TE - accepted. However, small sand filled components as i.e.
time shall be listed together with the release
time of the associated over current protection capacitors for Ex-e light fixtures are accepted.
IP-rating Ingress protection rating of the equipment d) Requirements for cables are found in D200.
DET NORSKE VERITAS

203 Zone 2 302 Frequency converter driven Ex-e and Ex-d motors
Equipment for zone 2 installation shall be in accordance with a) Ex-e motors driven by a power converter are not accepted
one of the following four alternatives: installed in zone 1 unless the converter and the motor are
certified together. The certificate shall state allowed mo-
a) Certified safe for zone 1 application. tor-converter combinations.
b) Certified safe for zone 2 application.
b) The requirement in a) applies also for Ex-d motors unless
c) Have a manufacturer conformity declaration stating that it the motors are equipped with embedded RTDs in the
is made in accordance with an Ex-n standard. windings and an over temperature trip device.
d) Documented by the manufacturer to be suitable for zone 2 c) For Ex-n motors driven by converters, a conformity decla-
installation. This documentation shall state compliance ration as described in 203 is required. This declaration
with a minimum enclosure protection of IP44, maximum shall include information on accepted type of converter.
temperature for internal or external surfaces according to
the temperature class for the area and that the equipment 303 Ex-p equipment
contains no ignition sources during normal operation.
a) For zone 1 installation, Ex-p protected equipment shall
204 Exceptional conditions or ESD normally be certified safe as a complete system by an in-
Equipment which is arranged to operate during exceptional dependent test institution (complete system being the
conditions, in which the explosion hazard extends outside the equipment, the enclosure, the purging and the control sys-
defined hazardous zones, is to be suitable for installation in tem).
Zone 2. Arrangements are to be provided to facilitate the selec- b) For zone 2 installation, Ex-p protected equipment may ei-
tive disconnection of other equipment in those areas not suita- ther be certified safe as for zone 1, or be verified safe by a
ble for installation in Zone 2. competent person before taken into service. Such verifica-
205 Battery rooms, paint stores, and gas bottle stores tion shall be documented in a verification report.
c) In zone 1 applications, automatic shutdown and or isola-
a) Electrical equipment installed in battery rooms, paint tion of equipment inside enclosures will be required upon
stores or gas bottle stores, and in ventilation ducts serving loss of pressurisation. If automatic shutdown increases the
such spaces shall be suitable for installation in zone 1 with hazard to the vessel, then other protection methods shall be
the following requirements for gas group and ignition tem- utilised for equipment that has to remain connected. In
perature: zone 2 applications, a suitable alarm at a manned control
station for indication of loss of overpressure is accepted,
— battery rooms: minimum gas group II C and tempera- instead of the automatic shutdown.
ture class T1
— paint stores: minimum gas group II B and temperature 304 Ex-i circuits
class T3
— gas bottle stores: minimum gas group II C and temper- a) All intrinsic safe circuits shall have a safety barrier in form
ature class T2. of a zener barrier or galvanic isolation certified safe for the
application in front of the circuit part going into hazardous
b) Cables routed through such spaces shall either be suitable areas.
for installation in hazardous area zone 1, or be installed in
metallic conduit. b) The complete intrinsic safe circuit shall not contain more
than the maximum allowed, inductance, (Leq) and or ca-
c) Switches, protective devices, motor controlgear of electri- pacitance (Ceq) than the barrier is certified for. The Leq
cal equipment installed in a such spaces are to interrupt all and Ceq, shall be the total of the cable out to the hazardous
poles or phases and are to be located in non-hazardous area plus the values of connected equipment.
spaces.
d) Areas on open deck within 1m of inlet and exhaust venti-
lation openings or within 3 m of exhaust outlets with me-
chanical ventilation are classified as zone 2. D. Installation Requirements
e) Enclosed spaces giving access to the such areas may be D 100 General
considered as non-hazardous, provided that:
101 General
— the door to the space is a gastight door with self-clos- For general installation requirements, see Sec.10. The follow-
ing devices and without holding back arrangements (a
ing clauses are requirements especially for hazardous area in-
watertight door is considered gastight)
stallations.
— the space is provided with an acceptable, independent,
natural ventilation system ventilated from a safe area 102 Ingress protection
— warning notices are fitted adjacent to the entrance to
the space stating that the store contains flammable liq- a) Ingress protection of equipment in relation to its location
uids or gas. shall in general be as described in Sec.10.
b) Minimum degree of enclosure protection for Ex-e equip-
C 300 Additional requirements for equipment and cir- ment is IP 54.
cuit design
c) Minimum IP degree of enclosures for Ex-n protected
301 Ex-e motors (increased safety) equipment is IP 44.
Motors certified Ex-e shall, when installed in zone 1, have an
overload or thermal protection that disconnects the motor be- Guidance note:
fore the TE-time is exceeded in a situation with locked rotor or A comparison between the IEC based IP-rating and the NEMA
some kind of machine stalling condition. types used in the USA is given in Table D1.
DET NORSKE VERITAS

Table D1 Corresponding values for NEMA-Type and IP-rating

NEMA-Type Description of NEMA-Type IP-rating Description of IP-rating
1 General purpose, indoor 11 Protection from solid objects larger than 55 mm
2 Suitable where severe condensation present 32 Protection against dripping water, spillage (not rain)
3 Weathertight against rain and sleet 54-55 Dustproof and resistant to splashing water (5) and rain (4)
(normal outdoor weatherproof)
3R Less severe than NEMA 3 14 Protected from water only (rarely used in the IEC system)
4 Watertight. Resistant to direct water jet spray 56 Dustproof and heavy water jets (like on an open deck)
4X Same as NEMA 4 although corrosion resistant, no
stainless or non-metallic equivalent
5 Dusttight 52 Dustproof and resistant to dripping water (not rain)
6 Limited submersion in water 67 Protected against effect of immersion maximum 1 m
(depth)
7 Explosion-proof. (Contains gaseous internal ig- no direct Flameproof (Ex-d) works by the same principal
nition) equivalent
12 Dusttight and dripproof 52 Dustproof and resistant to dripping water (not rain)
13 Oiltight and dusttight. (Constructed with special 54-55 Dustproof and resistant to splashing water and rain. (nor-
gasketing to resist oil and liquid chemical pene- mal outdoor weather proof)
tration)
103 Ex-d equipment 203 Penetrations of bulkheads and decks

a) Ex-d enclosures and its flameproof joints shall not be in- Cable penetrations through bulkheads and decks shall be gas
stalled nearer to a bulkhead or solid object than 10 mm for tight, and of a recognised make, if used as sealing between
gas group II A, 30 mm for II B, and 40 mm for II C. zones or between hazardous areas and non-hazardous areas.
b) Flameproof joints shall be protected against corrosion 204 Cable entrance into equipment
with suitable non-hardening grease.
a) In the case of direct entry into an Ex-d enclosure a certified
c) Gaskets can only be applied if originally fitted in the safe gland shall be applied according to the following in-
equipment from the manufacturer, and the equipment has structions:
been certified or tested with gaskets.
d) One layer of soft tape around the flameproof joint opening — Zone 1: Either barrier or compound filled type of
for corrosion protection is allowed for Ex-d enclosures in- gland shall be used, or a rubber compression type
stalled in areas with gas groups II A and II B, but not II C gland might be used provided it is not a II C area, and
areas. the Ex-d internal volume is below 2 dm3.
— Zone 2: Both barrier or compound filled type and
e) Tape into (on the threads of) flameproof joints of threaded compression type gland is accepted.
type, is not allowed.
f) Flameproof joints might be covered with a thin layer of b) For Ex-e, Ex-n and general non-sparking equipment the
paint on the outside. However, this is not accepted in II C cable gland shall maintain the required IP-rating for the
areas. enclosure in question.
c) Unused openings for cable glands shall be blanked off by
D 200 Wiring and termination suitable plugs according to the equipment's Ex-protection
201 Wiring method. For Ex-e and Ex-n type of protection, the sealing
plug shall maintain the required IP-rating for the enclosure
a) All cables installed in hazardous areas shall have an outer in question. For Ex-d equipment, with direct entry, the
overall sheath of a insulating non-metallic material. sealing plug shall be certified safe (Ex-d) for the relevant
b) Power and signal (non-intrinsic safe) cables in zone 0 and application.
zone 1 shall have a metallic braiding or armour between 205 Termination and wiring inside Ex-e and Ex-d enclosures
conductors and the outer insulating sheet. The metallic
covering shall serve as mechanical protection and be a) Only one conductor is allowed to be connected into an
earthed for PE-protection purposes according to the instal- Ex-e terminal.
lation requirements in Sec.10. See 206 for screening of in-
trinsic safe wiring. b) In certified empty Ex-e enclosures, only the maximum
amount of wiring and equipment stated in the certificate
c) In zone 0 only wiring for Ex-ia circuits are allowed. shall be installed within the enclosure.
d) In zone 1 trough runs of cables other than the ones intend- c) All components inside an Ex-e enclosure shall be certified
ed for Ex-equipment, shall be limited. safe with protection Ex-e, -d, -m or other approved method
e) In zone 2, trough runs of cables are accepted for zone 1 application.
202 Flexible cables d) Certified empty Ex-d (flameproof boxes) shall have a final
certificate taking into account the equipment installed
a) Flexible cables for non-intrinsically safe circuits shall be within the Ex-d enclosure during installation.
limited in hazardous areas and shall not be used perma-
nently in zone 1. 206 Intrinsically safe circuit wiring and termination
b) Fixed installation of shorter flexible lengths with a good a) Cables for intrinsically safe circuits shall have a common
support from connection boxes to equipment will be ac- metallic screen or braiding. Multicore cables for Ex-i cir-
cepted into zone 2. cuits shall have individual screened pairs.
DET NORSKE VERITAS

b) Terminals for intrinsically safe circuits and terminals for f) Ex-i circuits and non-intrinsically safe circuits shall not
non-intrinsically safe circuits shall be separated by recog- run in the same cable.
nisable marking (light blue), and with a physical distance g) Inside cabinets, screened wiring of non-intrinsically safe
of 50 mm. circuits can be laid in the same channel or tray as screened
c) Cable screens for shielding against interference with IS- intrinsically safe circuits. Unscreened conductors in intrin-
sically safe and non-intrinsically safe circuits do not need
circuits, shall be earthed at the supply end only. any separating distance provided that the parallel wiring
d) If cables have armour or braiding in addition to screening, length is below 1m, and that the intrinsically safe and non-
then the armour or braiding shall be connected to the pro- intrinsically safe conductors are not laid in the same cable
tective earth system at the power supply end only. or wiring bundle or wiring channel. For lengths longer
than 1 m, the conductors shall be run at least 50 mm apart,
e) Category Ex-ia- circuits intended for zone 0, and category or with an earthed metallic partition between the conduc-
Ex-ib-circuits shall not be run in the same cable. tors.
DET NORSKE VERITAS

SECTION 12
ELECTRIC PROPULSION
A. General different lines with the associated equipment for power distri-
bution to these lines arranged in different rooms, failure of
A 100 General ventilation or cooling shall only render one propulsion line out
101 Application of operation. However, redundancy requirements for main
class and relevant additional class notations shall be adhered
a) The technical requirements in this section are in addition to.
to those in Sec.2 to Sec.11 and apply to propulsion sys-
tems, where the main propulsion is performed by some A 300 System capacity
type of electric motor(s). 301 Torque
b) Prime movers for generators providing electric power for
propulsion shall be considered as propulsion prime mov- a) The torque available at the propeller shaft shall be ade-
ers. Prime movers and associated instrumentation and quate for the vessel to be manoeuvred, stopped, or re-
monitoring shall comply with the rule requirements for versed when the vessel is sailing at full speed.
propulsion prime movers. Associated speed governing and b) Adequate torque margin shall be provided to guard against
control shall be arranged as for auxiliary prime movers. the motor pulling out of synchronism during rough weath-
c) Prime movers that drive generators for the supply of power conditions or manoeuvres.
er for vessel service only, are defined as auxiliary prime c) Sufficient run-up torque margin shall be provided to en-
movers, even if they may be connected to the propulsion sure a reliable start under all ambient conditions.
power system and thus contribute to propulsion power.
d) Required locked rotor torque shall be considered in view
d) Local and remote control systems for electric propulsion of the operation of the vessel.
machinery shall comply with main class rules.
e) For instrumentation and automation, including computer Guidance note:
based control and monitoring, the requirements in this For thrusters, a gear oil temperature of 0°C should be considered.
chapter are additional to those given in DNV-OS-D202. ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
Guidance note: 302 Torsional vibrations in propulsion unit
Attention should be given to any relevant statutory requirements
of national authority of the country in which the vessel shall be The following torsional vibration calculations are to be sub-
registered. mitted (when applicable) for all propulsion units (motor,
torque transmission system and propeller) above 200 kW rated
power:
A 200 System design a) Torsional vibration calculations for steady state condi-
201 System arrangement tions, see B100.
b) Torsional vibration calculations for transient conditions:
a) Electrical equipment in propulsion lines, which have been
built with redundancy in technical design and physical ar- — Starting operations. This applies when requested by
rangement, shall not have common mode failures endan- the Society in order to prove that starting procedures
gering the manoeuvrability of the vessel, except for fire due to impacts loads caused by direct start-up or star-
and flooding, which are accepted as common mode fail- delta switchover of asynchronous motors is not detri-
ures. mental to any power transmitting parts, see B401.
b) Vessels having two or more propulsion motors and con- — Short circuit in electric motors. This applies to plants
verters, or two electric motors on one propeller shaft, shall with motors where short circuits can occur. Transient
be arranged so that any unit may be taken out of service vibration calculations due to short circuiting will be
and electrically disconnected without affecting the opera- required if the ratio between torsional dynamic stiff-
tion of the others. ness (kNm/rad) and rated torque (kNm) exceeds 10
c) Vessels having only one propulsion motor will be accept- (considering the excitation frequency of 50 Hz or 60
ed as being built with redundancy in technical design and Hz), that is Kdyn/To > 10, in any parts of the shaft
physical arrangement, with respect to single failures, as lines, see B402.
long as the motor is equipped with two independent sets of Any changes to components after the calculations are
armature windings. These sets shall not be laid in the same completed are not acceptable unless verified through new
slots in the iron core. analysis or equivalent methods.
d) Vessels having only one propulsion motor of non-self ex- 303 Overload capacity
citing type having armature windings as required by c), but
only one common field winding will be accepted without The system is to have sufficient overload capacity to provide
further redundancy when equipped with more than one ex- the necessary torque, power, and for A.C. systems reactive
ternal exciter. power, needed during starting, manoeuvring and crash stop
conditions.
202 Ventilation
The general requirements in Sec.2 will normally imply that A 400 Electric supply system
loss of ventilation or cooling to spaces or equipment with 401 Electric supply system
forced air-cooling, shall not cause loss of propulsion. Suffi-
cient power necessary for manoeuvring shall be available after a) The electric distribution system shall comply with the re-
any single failure. Where the propulsion system is arranged in quirements in Sec.2.
DET NORSKE VERITAS

b) The required split of the main switchboard shall be by bus d) The thrust is not to increase substantially in case of loss of
tie breaker(s) capable of breaking any fault current that an actual value signal from a discrete transmitter or loss of
might occur at the location where it is installed. a reference value in the system.
c) Frequency variations shall be kept within the limits given e) Means for emergency stop of propulsion motors shall be
in Sec.2. During crash-stop manoeuvres, it will be accept- arranged at all control locations. The emergency stops
ed that voltage and frequency variations exceed normal shall be independent of the normal stop, and separate for
limits, if other equipment operating on the same net is not each propulsion line.
unduly affected.
Guidance note:
A 500 System protection It is accepted that ahead and astern thrust output will be different
due to the propeller characteristics.
501 Automatic voltage regulator failure
It is accepted that an emergency stop system has common power
Where a single failure in the generators’ excitation systems supply for several propulsion motors, as long as each motor can
may endanger the manoeuvrability of the vessel, provisions be stopped by this system independently of the other motors, and
shall be made to monitor the proper operation of the excitation as long as a single failure in this emergency stop system cannot
system. Upon detection of abnormal conditions, an alarm shall cause loss of manoeuvrability.
be given on the navigating bridge and in the engine control ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
room and actions to bring the system into a safe operational
mode shall be automatically executed. 603 Power plant control
Guidance note: a) When electric propulsion is utilised, the electric power
An accepted action will be to automatically open the bus tie generation and distribution system shall be equipped with
breaker in the main switchboard so that different sections of the an automatic control system having at least the following
main bus bar work independently of reactive load sharing. functions:
— ensure adequate power for safe manoeuvring is avail-
502 Overspeed and regeneration able at all times
— ensure even load sharing between on-line generators
a) When necessary, overspeed protection of propulsion mo- — execute load tripping and/or load reduction when the
tors shall be arranged, preventing the speed during ma- power plant is overloaded
noeuvring or fault conditions to exceed the limits for — ensure that adequate power for safe manoeuvring is
which the machine has been designed. available also if one running generator is tripped.
If necessary by tripping of non-essential consumers
b) Regenerated power shall not cause any alarms in the pro- — no changes in available power shall occur if the auto-
pulsion system, neither in planned operating modes nor matic control system fails, that is no start or stop of
during emergency manoeuvres. Where necessary, braking generators shall occur as an effect of a failure
resistors for absorbing or limiting such energy shall be — control the maximum propulsion motor output.
provided.
b) The control system shall initiate an alarm, to the operator,
503 Motor excitation circuits when adequate power is no longer available.
a) Circuit protection in an excitation circuit shall not cause Guidance note:
opening of the circuit, unless the armature circuits are dis- The control system may have a selector for transit or manoeuvre
connected simultaneously. mode, enabling operation with different levels of reserve power
b) For a motor with one excitation winding and two armature in these two modes of operation.
windings, a failure in one of the armature circuits, shall not ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
entail disconnection of the excitation circuit in operation.
604 Monitoring and alarms
A 600 Control systems
a) Safety functions installed in equipment and systems for
601 General electric propulsion shall not result in automatic shut down
The following control functions are part of the electric propul- unless the situation implies that the equipment is not capa-
sion system: ble of further functioning, even for a limited time. Auto-
matic reduction of propulsion power is accepted.
— propulsion control b) Priming control shall not prevent blackout start, if ar-
— power plant control. ranged.
602 Propulsion control c) Shutdowns caused by a safety function shall, as far as pos-
sible, be arranged with a pre-warning alarm.
a) The electric propulsion system shall be equipped with d) For installations with one propulsion motor having two
means for “emergency propulsion control”. These means separate armature windings, the converters shall be ar-
shall be understood as a method of controlling the equip- ranged for automatic restart if an excitation failure in the
ment that constitutes the propulsion system. These means motor may cause shutdown of both propulsion converters.
shall be independent of the normal propulsion remote con-
trol system. e) Critical alarms for propulsion shall be relayed to the navi-
gation bridge and displayed with separate warnings sepa-
b) Failure of the remote propulsion control system shall not rated from group alarms.
cause appreciable change of the thrust level or direction
and shall not prohibit local control. f) Monitoring with alarm shall be arranged for:
c) The normal propulsion remote control system shall in- — high temperature of cooling medium of machines and
clude means for limiting the thrust levels when there is not semi-conductor converters having forced cooling
adequate available power. This may be an automatic pitch — high winding temperature of all propulsion generators
or speed reduction. and motors
DET NORSKE VERITAS

— loss of flow of primary and secondary coolants of ma- The calculations are to contain:
chines and semi-conductor converters having closed
cooling method with a heat exchanger, when this flow — objectives
is not caused by the propulsion motor itself. Auxiliary — description of the method
contacts from motor starters may be used for this pur- — plant or system layout
pose — conditions
— lubricating oil pressure for machines with forced oil — assumptions
lubrication — conclusion.
— leakage of water-air heat exchanger for cooling of ma-
chines and semi-conductor converters The source of all essential data is to be listed. For data that can-
— earth fault for main propulsion circuits not be given as constant parameters (e.g. see 102), the assumed
— earth fault for excitation circuits. (This may be omit- parameter dependency and/or tolerance range is to be speci-
ted in circuits of brushless excitation systems and for fied.
machines rated less than 500 kW) The conclusion is to be based on a comparison between calcu-
— fuses for filter units, or for other components where lated dynamic response and the permissible values for all the
fuse failure is not evident. sensitive parts in the plant.
g) A request for manual load reduction shall be issued, visu- 102 Parameter uncertainty
ally and acoustically on the bridge, or an automatic load In all vibration calculations the variation of essential data such
reduction shall be arranged in case of: as dynamic characteristics of flexible couplings, bearings, and
— low lubricating oil pressure to propulsion generators foundations, are to be considered. In particular, rubber cou-
and motors plings that have wide tolerances for stiffness and damping are
to be considered. Normally, it is not required to perform calcu-
— high winding temperature in propulsion generators lations with all combinations of these extreme data, but as a
and motors minimum the influence of such wide tolerances is to be quali-
— failure of cooling in machines and converters. tatively considered and addressed in the conclusions.
Guidance note: For couplings having stiffness with strong dependency on vi-
High-high, or extreme high, temperatures may, when higher than bratory torque and/or mean torque and/or temperature (as a
the high alarm limit, cause shut down of the affected equipment. consequence of power loss) it may be required to carry out ei-
For redundancy requirements, see 200. Critical alarms for pro- ther iterative direct calculations or simulation calculation
pulsion machinery are alarms causing automatic shutdown or where these dependencies are included.
load reduction of parts of the propulsion power.
103 Symbols and definitions
Symbols and definitions are to be in compliance with the Rules
605 Instruments for Classification of Ships, Pt.4 Ch.3 Sec.1 G101 and Pt.4 Ch.3
Sec.1 G102.
a) A temperature indicator for directly reading the tempera-
ture of the stator windings of generators and propulsion B 200 Vibration measurements
motors shall be located in the control room. 201 Reference
b) The following values shall be displayed in the control Rule requirements are to be in compliance with the Rules for
room or on the applicable converter: Classification of Ships, Pt.4 Ch.3 Sec.1 G201 and Pt.4 Ch.3
— stator current in each motor Sec.1 G202.
— field current in each motor (if applicable). B 300 Steady state - torsional vibration
c) For each generator: A power factor meter or kVAr meter. 301 Extent of calculations
d) On the bridge and in the control room, instruments shall be Natural frequency calculations are to be carried out in compli-
provided for indication of consumed power and power ance with the Rules for Classification of Ships, Pt.4 Ch.3 Sec.1
available for propulsion. G301 item a).
e) At each propulsion control stand, indications, based on In the case where there is a resonant condition in the running
feedback signals, shall be provided for pitch or direction of range, forced response calculations in conjunction with stress
rotation, speed, and azimuth, if applicable. calculations are required to prove that failure of the shafting
f) Indications as listed for control stands shall be arranged in will not occur as a result of high cycle fatigue.
the engine control room, even if no control means are pro- 302 Calculation method
vided.
To be in compliance with the Rules for Classification of Ships,
Guidance note: Pt.4 Ch.3 Sec.1 G302 items a), c), d), h) and j).
When the rated power of semi-conductors is a substantial part of If excitations caused by the electric motor are included in the
the rated power of the generators, it should be ensured that meas- forced vibration calculation the excitation models shall be doc-
urements are displayed in true root mean square values. Temper- umented.
ature indicators may be omitted for winding temperatures that are
displayed on the alarm system display. 303 Acceptance criteria
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- To be in compliance with the Rules for Classification of Ships,
Pt.4 Ch.3 Sec.1 G303 items d), e), f), g) and h).
B 400 Transient torsional vibration
B. Torsional Vibrations 401 General
Transient vibration caused by the electric motor are not to be
B 100 General detrimental to the power transmitting elements, such as cou-
101 Documentation plings and gears.
DET NORSKE VERITAS

Transient torsional vibration can be analysed by simulation us- Transient torsional vibrations are to be in compliance with the
ing numeric integration in the time domain. The purpose of the Rules for Classification of Ships, Pt.4 Ch.3 Sec.1 G405.
calculation is to determine the peak torque and torque ampli-
tudes that occur before the safety system (circuit breaker) be-
comes active.
The plant can be described as a lumped mass system, but es- C. Verification
sentially simplified as described in the Rules for Classification
of Ships, Pt.4 Ch.3 Sec.1 G302 item e). C 100 Factory testing or manufacturer’s testing
402 Starting operations 101 Survey and test upon completion
Impact load analyses of direct start-up and star-delta switcho- a) Upon completion, the electric propulsion system shall be
ver for asynchronous motors are to be analysed, upon request subject to final tests at a sea trial.
by the Society, see A302 item b).
b) The final test at sea assumes that satisfactory tests of all
403 Short circuit in electric motors subsystems have been carried out.
Impact load analyses of short circuit excitation torque is to be c) The test program is to include tests of the propulsion plant
analysed for propulsion units according to A302 item b). in normal and abnormal conditions.
If the short circuit excitation torque (in the air gap between ro- d) Start-up and stop sequences shall be tested, also as control-
tor and stator) is not specified, it can be assumed as: led by the power management system, when relevant.
T = T0 ⋅[10⋅e-t/0.4⋅sin(Ω t) − 5⋅e-t/0.4⋅sin(2Ω t)] e) Safety functions, alarms and indicators shall be tested.
Ω/2π = net frequency (50 or 60 Hz) f) All control modes shall be tested from all control loca-
t = time (s). tions.
The duration to be considered is 1 s. g) Required level of redundancy shall be verified through
404 Acceptance criteria tests.
DET NORSKE VERITAS

SECTION 13
DEFINITIONS
A. Definitions — scavenging air blower, fuel oil supply pumps, fuel

valve cooling pumps, lubricating oil pumps and fresh-
A 100 General water cooling water pumps for main and auxiliary en-
101 Electrical installations gines
— viscosity control equipment for heavy fuel oil
The term electrical installations is an all-inclusive general ex- — ventilation necessary to maintain propulsion
pression that is not limited to the physical installations. For — forced draught fans, feed water pumps, water circulat-
physical installations, the wording, "installation of…" is used. ing pumps, condensate pumps, oil burning installa-
102 Normally tions, for steam plants on steam turbine vessels, and
also for auxiliary boilers on vessels where steam is
The term "normally", or "normally not", when used in these used for equipment supplying primary essential serv-
rules, shall basically be understood as a clear requirement in ices
line with "shall", or "shall not". However, upon request, other — steering gears
designs may be accepted. — azimuth thrusters which are the sole means for propul-
If the rules are used for a vessel classed by DNV, then the So- sion or steering - with lubricating oil pumps, cooling
ciety shall be requested, in writing, to accept a deviating de- water pumps
sign. A request giving the reasons for the design shall be — electrical equipment for electric propulsion plant -
submitted. with lubricating oil pumps and cooling water pumps
— pumps or motors for controllable pitch propulsion or
A 200 Operational conditions steering propellers, including azimuth control
— hydraulic pumps supplying the above equipment
201 Normal operational and habitable condition
— electric generators and associated power sources sup-
Normal operational and habitable condition: A condition under plying the above equipment.
which the vessel, as a whole, is in working order and function-
ing normally. As a minimum, the following functions shall be 302 Important services
operational: Propulsion machinery, steering gear, safe naviga-
tion, fire and flooding safety, internal and external communi- a) Important (secondary essential) services are those services
cations and signals, means of escape, emergency boat winches, that need not necessarily be in continuous operation for
anchor winches. Additionally, designed comfortable condi- maintaining for the vessel’s manoeuvrability, but which
tions for habitability, including; cooking, heating, domestic re- are necessary for maintaining the vessels functions as de-
frigeration, mechanical ventilation, sanitary and fresh water. fined in the Rules for Classification of Ships, Pt.1 Ch.1
All utility systems for the listed functions shall be included. Sec.2, or other relevant parts of the rules. Important elec-
trical consumers are electrical consumers serving impor-
202 Emergency condition tant services. Additional class notations may extend the
An emergency condition is a condition under which any serv- term important services. Such extensions, if any, can be
ices needed for normal operational and habitable conditions found in the relevant rule chapters.
are not in working order due to the failure of the main source b) Examples of equipment or systems for important services
of electrical power. covered by main class:
203 Dead ship condition
— anchoring system
Dead ship condition is the condition under which the main pro- — thrusters not part of steering or propulsion
pulsion plant, boilers and auxiliaries are not in operation due to — fuel oil transfer pumps and fuel oil treatment equip-
the absence of power. Batteries and or pressure vessels for ment
starting of the main and auxiliary engines are considered de- — lubrication oil transfer pumps and lubrication oil treat-
pleted. Emergency generation is considered available. For a ment equipment
more detailed definition of dead ship, see the Rules for Classi- — pre-heaters for heavy fuel oil
fication of Ships, Pt.4 Ch.1. — seawater pumps
204 Blackout condition — starting air and control air compressors
— bilge, ballast and heeling pumps
Blackout is a sudden loss of electric power in the main distri- — fire pumps and other fire extinguishing medium appli-
bution system. All means of starting by stored energy is avail- ances
able. — ventilating fans for engine and boiler rooms
— ventilating fans for gas dangerous spaces and for gas
A 300 Services safe spaces in the cargo area on tankers
301 Essential services — inert gas fans
— navigational lights, aids and signals
a) Essential (primary essential) services are those services — internal safety communication equipment
that need to be in continuous operation for maintaining the — fire detection and alarm system
vessel’s manoeuvrability in regard to propulsion and steer- — main lighting system
ing. Additional class notations may extend the term essen- — electrical equipment for watertight closing appliances
tial services. Such extensions, if any, can be found in the — electric generators and associated power sources sup-
relevant rule chapters. plying the above equipment
b) Examples of equipment and or systems for essential serv- — hydraulic pumps supplying the above equipment
ices covered by main class: — control, monitoring and safety systems for cargo con-
tainment systems
— control, monitoring and safety devices or systems for — control, monitoring and safety devices or systems for
equipment for essential services equipment to important services.
DET NORSKE VERITAS

303 Emergency services ery. Hazardous areas are divided into zone 0, 1, and 2 in
accordance with an area classification.
a) Emergency services are those services that are essential
for safety in an emergency condition. b) If electrical installations are based on an areas' classifica-
tion, this classification shall be based on a relevant IEC
b) Examples of equipment and systems for emergency serv- standard.
ices:
602 Certified safe equipment
— equipment and systems that need to be in operation in Certified safe equipment is equipment certified by an inde-
order to maintain, at least, those services that are re- pendent national test institution or competent body to be in ac-
quired to be supplied from the emergency source of cordance with a recognised standard for electrical apparatus in
electrical power hazardous areas.
— equipment and systems that need to be in operation in
order to maintain, at least, those services that are re- 603 Marking of certified safe equipment
quired to be supplied from the accumulator battery for Certified safe equipment shall be marked in accordance with a
the transitional source(s) of emergency electrical recognised standard for electrical apparatus in hazardous are-
power as. This includes at least:
— equipment and systems for starting and control of
emergency generating sets — Ex-protection type and Ex certificate number
— equipment and systems for starting and control of — temperature class, according to Table A2
prime movers (e.g. diesel engines) for emergency fire — gas and equipment group, according to Table A1.
fighting pumps
— equipment and systems that need to be in operation for Table A1 Equipment and gas groups
the purpose of starting up manually, from a "dead Gas groups (IEC sur- Representative gas NEC 500
ship" condition, the prime mover of the main source of face industry (US surface
electrical power (e.g. the emergency compressor) = II) industry
= class 1)
— equipment and systems that need to be in operation for
the purpose of fire fighting in the machinery spaces. II A Propane Group D
This includes emergency fire fighting pumps with II B Ethylene Group C
their prime mover and systems, when required accord- II C Hydrogen Group B
ing to the Rules for Classification of Ships, Pt.4 Ch.10 II C Acetylene Group A
Sec.2 B
— equipment and systems that are needed for the pur-
pose of exhausting or removing for example CO2 fire
extinguishing medium from the machinery spaces af- Table A2 Temperature classes
ter a fire, in order to allow for access to the spaces. Temperature classes Ignition temperature Corresponding
(equipment maximum of gas or vapour NEC (US) tem-
c) Further requirements for emergency services are given in temperature) (°C) perature classes
Sec.2. IEC and EN norms
T1 Above 450 T1
304 Non-important services
T2 Above 300 T2*
Non-important services are those services not defined as es- T3 Above 200 T3*
sential or important; or those services that are not defined, ac-
T4 Above 135 T4*
cording to 301, 302 and 303.
T5 Above 100 T5
A 400 Installation T6 Above 85 T6
401 Short circuit proof installation * Intermediate values of temperature classes by letter marking ABCD ex-
ist.
Short circuit proof installation means one of the following
three methods: Guidance note:
According to the "ATEX"-directive that will enter into force in
— bare conductors mounted on isolating supports Europe by 2002, all electrical equipment suitable for installation
— single core cables without metallic screen or armour or in a hazardous area shall be marked in accordance with the re-
quirements given in this directive. The new marking shall be in
braid, or with the braid fully insulated by heat shrink addition to Ex-marking related to the various protection methods
sleeves in both ends (enabling easy identification for in which zone it can be in-
— insulated conductors (wires) from different phases kept stalled).
separated from each other and from earth by supports of ATEX directive divides equipment into 3 safety categories,
insulating materials, or by the use of outer extra sleeves. marked on equipment:
A 500 Area definitions — Category 1 equipment is allowed, if certified safe, into zone
0.
501 Open deck — Category 2 equipment is allowed, if certified safe, into zone
Open deck is a deck that is completely exposed to the weather 1.
from above or from at least one side. — Category 3 equipment is suitable for zone 2 only.
A 600 Hazardous area The letter G indicates the equipment suitability for gas atmos-
pheres.
601 Area definitions The letter D indicates the equipment suitability for dust atmos-
pheres.
a) A hazardous area is an area (zones and spaces) containing Marking of protection methods, gas grouping, temperature class,
a source of hazard and or in which explosive gas and air etc., corresponds to the IEC 60079 standard system (or equiva-
mixture exists, or may normally be expected to be present lent to the CENELEC 50014-39 standard series) as given in 603.
in quantities such as to require special precautions for the
construction and use of electrical equipment and machin- ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
DET NORSKE VERITAS

604 TE-time (EDB) and all cables from the emergency generator to the
The TE –time is the time it takes for the motor, starting from final consumer.
normal operating temperature, to reach the temperature given b) A transitional source of power is considered to be part of
by the temperature class of the Ex certification if the rotor is the emergency electric power supply system.
locked. The TE-time is stated in the Ex-certificate for the mo- c) Control systems and auxiliary systems needed to be in op-
tor. eration for the above mentioned systems or equipment are
605 Simple apparatus included in this term.
a) A simple (non-energy storing) apparatus is an electrical 705 Main generating station
component of simple construction with no, or low energy
consumption or storage capacity, and which is not capable A main generating station is a space in which the main source
of igniting an explosive atmosphere. Normal maximal of electrical power is situated.
electrical parameters are 1.5 V, 100 mA and 25 mW. The 706 System with high resistance earthed neutral
component shall not contain inductance or capacitance. A system with high resistance earthed neutral is a system
Components such as thermocouples or passive switches where the neutral is earthed through a resistance with numeri-
are typical examples of simple, non-energy storing, appa- cal value equal to, or somewhat less than, 1/3 of the capacitive
ratus. reactance between one phase and earth.
b) Simple (non-energy storing) apparatus, when used in an 707 System with low resistance earthed neutral
intrinsically safe circuit, generally does not need to be cer-
tified safe, provided that such apparatus is constructed in A system with low resistance earthed neutral is a system where
accordance with IEC 60079-14, Part 14: "Electrical appa- the neutral is earthed through a resistance which limits the
ratus for explosive gas atmospheres". earth fault current to a value of minimum 20% and maximum
100% of the rated full load current of the largest generator.
A 700 Sources of power, generating station and distribu-
tion 708 Conductor, core, wire, cable
701 Main source of electrical power a) A conductor is a part of a construction or circuit designed
A main source of electrical power is a source intended to sup- for transmission of electric current.
ply electrical power to the main switchboard(s) for distribution b) A core is an assembly consisting of a conductor and its
to all services necessary for maintaining the vessel in normal own insulation.
operational and habitable conditions. c) A wire is an assembly consisting of one core where the in-
Guidance note: sulation is at least flame retardant.
Main source of electrical power may be generators and/or batter- d) In electrical terms, a cable is an assembly consisting of:
ies.
A generator prime mover and associated equipment is called — one or more cores
"generators' primary source of power". — assembly protection
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- — individual covering(s) (if any)
— common braiding (if any)
702 Emergency source of electrical power — protective covering(s) (if any)
An emergency source of electrical power is a source intended — inner and/or outer sheath.
to supply the emergency switchboard and/or equipment for
emergency services in the event of failure of the supply from Additional uninsulated conductors may be included in the
the main source of electrical power. cable.
Guidance note: e) A cable may be either Class 2 or Class 5 as defined in IEC
Emergency source of electrical power may be generator(s) or 60228. In a Class 2 cable the conductor is made up by a
battery(ies). minimum number of strands. In a Class 5 cable the con-
ductor is made up by many small strands with a maximum
A generator prime mover and associated equipment is called
"emergency generators' primary source of power". size according to IEC 60288.
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 709 Neutral conductor
703 Main electric power supply system A neutral conductor is a conductor connected to the neutral
point of a system, and capable of contributing to the transmis-
a) A main electric power supply system consists of the main sion of electric energy.
source of electric power and associated electrical distribu-
tion. This includes the main electrical generators, batter- A 800 Switchboard definitions
ies, associated transforming equipment if any, the main 801 Main switchboard (MSB)
switchboards (MSB), distribution boards (DB) and all ca-
bles from generators to the final consumer. a) A main switchboard is a switchboard directly supplied by
the main source of electrical power or power transformer
b) Control systems and auxiliary systems needed to be in op- and intended to distribute electrical energy to the vessel’s
eration for the above mentioned systems or equipment are services.
included in this term.
b) Switchboards not being directly supplied by the main
704 Emergency electric power supply system source of power will be considered as main switchboards
when this is found relevant from a system and operational
a) An emergency electric power supply system consists of point of view.
the emergency source of electric power and associated
electrical distribution. This includes emergency genera- Guidance note:
tors, batteries, associated transforming equipment if any, Normally, all switchboards between the main source of electrical
the transitional source of emergency power, the emergen- power and (inclusive) the first level of switchboards for power
cy switchboards (ESB), emergency distribution boards distribution, to small power consumers, will be considered to be
DET NORSKE VERITAS

main switchboards (MSBs) (i.e. at least first level of switch- — Switchgear: A common term for devices used for
boards for each voltage level used). making and breaking circuits, including auxiliary
Cubicles for other system voltages attached to a main switch- components such as for example short circuit and
board are considered part of the main switchboard. overcurrent relays, coils, etc.
c) Proof tracking index is the numerical value of the proof
802 Emergency switchboard (ESB) voltage, in volts, at which a material withstands 50 drops
without tracking, in accordance with IEC 60112 (i.e. a
a) An emergency switchboard is a switchboard, which in the voltage value describing the isolating materials surface
event of failure of the main electrical power supply sys- property to withstand tracking when wet.) Determination
tem, is directly supplied by the emergency source of elec-
trical power and/or the transitional source of emergency of the tracking index shall be done in accordance with the
power and is intended to distribute electrical energy to the requirements in IEC 60112, and is normally done by type
emergency power consumers. testing of the material by the manufacturer, before the ma-
terial is available in the market.
b) Switchboards not being directly supplied by the emergen-
cy source of power may be considered as emergency 902 Ingress protection of enclosures
switchboards when this is found relevant from a system
and operational point of view. Ingress protection of enclosures in regard to intrusion of parti-
cles and water, normally called IP rating, is defined as follows:
Guidance note:
Normally all switchboards between the emergency source of Table A3 Ingress protection of enclosures
electrical power and (inclusive) the first level of switchboards,
for power distribution to small power consumers, will be consid- First Protection against intrusion of particles and against ac-
ered to be emergency switchboards (ESBs) (i.e. at least one level charac- cidental touching of live parts
of switchboards for each voltage level used). teristic
numeral
---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- 0 Non-protected
803 Distribution board (DB) and emergency distribution 1 Protected against solid objects greater than 50 mm
board (EDB) 2 Protected against solid objects greater than 12.5 mm
A distribution board or an emergency distribution board is any 3 Protected against solid objects greater than 2.5 mm
switchboard utilised for distribution to electrical consumers, 4 Protected against solid objects greater than 1.0 mm
but which is not considered as a main or emergency switch- 5 Dust protected
board. 6 Dust tight
A 900 Components and related expressions Second Protection against intrusion of water
charac-
901 Definitions of words used in relation to electrical com- teristic
ponents and equipment numeral
0 Non-protected
a) For definitions of terms related to switchgear and con-
1 Protected against dripping water
trolgear, see IEC 60947-1 for low voltage, and IEC 60470
and IEC 60056 for high voltage equipment. 2 Protected against dripping water when tilted up to 15º
3 Protected against spraying water from above up to 60º
b) For assemblies, the following definitions are used in the from vertical
rules:
4 Protected against splashing water
— Controlgear: A general term for devices used for con- 5 Protected against water jets
trolling consumer equipment, e.g. by switching on and 6 Protected against heavy seas
off, starting and stopping a motor, controlling a mo- 7 Protected against the effects of immersion
tor’s speed.
— Electrical components: electrical units for use in elec- 8 Protected against submersion (water depth to be given)
trical equipment. A component is ready made by a
component manufacturer, for use by an equipment
manufacturer. The term component is also used for
smaller free-standing equipment like connection box-
es, sensors, switches etc.
— Electrical equipment: A common term for electrical
machines, transformers, switchboards, panels, assem-
blies, control units and other units made by compo-
nents.
— Semi-conductor assembly: Electrical equipment that
uses semi-conductors as the main active elements, for
switching or conducting the main flow of power.
DET NORSKE VERITAS

DET NORSKE VERITAS

OFFSHORE STANDARD
DNV-OS-D201
CHAPTER 3
CERTIFICATION AND CLASSIFICATION
CONTENTS PAGE
Sec. 1 Certification and Classification - Requirements ...................................................................... 85
DET NORSKE VERITAS

SECTION 1
CERTIFICATION AND CLASSIFICATION - REQUIREMENTS
A. General B 200 Certificate types

201 DNV defines two levels of documentation depending on
A 100 Introduction importance of equipment and experience gained in service:
101 As well as representing DNV’s recommendations on Works certificate (W) is a document signed by the manufacturer
safe engineering practice for general use by the offshore indus- stating:
try, the offshore standards also provide the technical basis for
DNV classification, certification and verification services. — conformity with the rule or standard requirements
102 A complete description of principles, procedures, appli- — that the tests are carried out on the certified product itself
cable class notations and technical basis for offshore classifi- — that the tests are made on samples taken from the certified
cation is given by the DNV offshore service specifications for product itself
classification, see Table A1. — that the tests are witnessed and signed by a qualified de-
partment.
Table A1 DNV Offshore Service Specifications
The manufacturer shall have a quality system that is suitable
No. Title for the kind of certified product. The surveyor shall check that
DNV-OSS-101 Rules for Classification of Offshore Drilling and the most important elements of this quality system are imple-
Support Units mented and may carry out random inspections at any time. The
DNV OSS-102 Rules for Classification of Floating Production component shall be marked to be traceable to the work certifi-
and Storage Units cate.
A 200 Certification and classification principles DNV certificate (NV) is a document signed by a surveyor of the
Society stating:
201 Electrical systems and equipment will be certified or
classified based on the following main activities: — conformity with the rule or standard requirements
— that the tests are carried out on the certified product itself
— design verification
— that the tests are made on samples taken from the certified
— equipment certification product itself
— survey during construction and installation — that the tests are made in the presence of a surveyor from
— survey during commissioning and start-up. the Society or in accordance with special agreements.
A 300 Assumptions The product shall be stamped with a special NV-stamp tracea-
301 Any deviations, exceptions and modifications to the de- ble to the certificate.
sign codes and standards given as recognised reference codes
shall be documented and approved by DNV. B 300 Type approval
302 Aspects of the design and construction provisions of 301 Type approval is a procedure for design assessment.
this standard which shall be specially considered, agreed upon, Type approval can be applied to a:
or may be accepted are subject to DNV approval when the
standard is used for classification purposes. — product
— group of products
303 DNV may accept alternative solutions found to repre- — system.
sent an overall safety level equivalent to that stated in the re-
quirements of this standard. This procedure should be used for design assessment of stand-
ard designs.
A 400 Documentation requirements
302 The type approval procedure will normally consist of the
401 Documentation for classification shall be in accordance following elements:
with DNV-RP-A201 and 202. DNV-RP-A202 lists detailed
document requirements for classification projects, while — design approval
DNV-RP-A201 describes applicable standard document types. — type testing
402 All documentation requirements listed in DNV-RP- — issuance of type approval certificate.
A202 under CIBS code 33, ‘Electrical power’ are applicable.
For other CIBS codes, document related to discipline E - Elec- The type approval procedure used by the DNV is described in
trical are applicable. standard for certification No. 1.2.
303 For certain products, equipment and systems as defined
in applicable DNV offshore standards, type approval is suffi-
cient as the assessment needed for conforming product quality,
B. Certification of Products i.e. production assessment is not required.
B 100 General 304 For certain products, equipment and systems as defined
in the applicable DNV offshore standards, type approval is a
101 The product certification is a conformity assessment mandatory procedure for design assessment.
normally including both design and production assessment.
305 For products, equipment and systems manufactured for
The production assessment includes inspection and testing stock, type approval shall be the normal procedure for assess-
during production and/or of the final product. ment of design.
102 Components shall be certified consistent with its func-
tions and importance for safety. The principles of categorisa- B 400 Certification requirements for electrical equip-
tion of component certification are given in the relevant ment
offshore service specifications, see Table A1. 401 Required Certificates
DET NORSKE VERITAS

a) Electrical equipment serving essential or important func- less otherwise stated in the certificate. A reference to the
tions and cables shall be delivered with certificates as re- type approval certificate shall substitute the required doc-
quired by Table B1. umentation for DNV design assessment.
d) A product certificate may be issued based on the type ap-
b) Additional requirements to certification may be given by proval certificate and a product survey, unless otherwise
other relevant parts of the DNV offshore standards. stated in the type approval certificate.
c) Equipment covered by a valid type approval certificate is
generally accepted without further design verification , un-
Table B1 Required certificates

DNV type approval
Equipment Rating DNV certificate (NV) Works certificate (W) certificate (TA)
Main and emergency switchboards all ratings X
≥ 100 kW/kVA X
Distribution switchboards, motor start-
ers, motor control centres, etc. ≥ 10 kW/kVA and <
100 kW/kVA X
≥ 300 kVA X
≥ 100 kVA and < 300
Generators 4) and transformers kVA 1) X X
≥ 10 kVA and < 100
kVA X
≥ 300 kW X
4) ≥ 100 kW and < 300
Motors kW 1) X X
≥ 10 kW and < 100 kW X
Semiconductor assemblies for motor ≥ 100 kW X
drives ≥ 10 kW and < 100 kW X
Semiconductor assemblies for UPSs or ≥ 100 kVA X
battery chargers < 100 kVA X
Cables 1), 2) all ratings X
Electrical equipment installed in hazard-
ous areas 3) all ratings - - -
1) As an alternative to the acceptance based on a type approval certificate (TA) and a works certificate (W), the electrical equipment will also be accepted
on the basis of a DNV product certificate (NV).
2) All cables – except cables for internal use in electrical assemblies or short lengths on mechanical packages.
3) All electrical installations in hazardous areas, and areas that may be become hazardous by accidental release of explosive gas, are to comply with the re-
quirements for certification and documentation given in Ch.2 Sec.11.
4) Material certificates for shafts shall be issued as required by DNV-OS-D101.
Note:
Heat exchangers used in conjunction with certified electrical equipment, shall be certified as required for pressure vessels, see DNV-OS-D101.
B 500 Survey during construction — review of the manufacturers documentation

501 General requirements for survey during construction are — visual inspection
stated in the relevant DNV offshore service specification for — testing.
classification, see Table A1.
b) Visual inspection shall verify that:
502 The contractors shall operate a quality management sys-
tem applicable to the scope of their work. The system shall be — manufacturing and installation is in accordance with
documented and contain descriptions and procedures for qual-
ity critical aspects. the approved design information
— the product manufacturing is in accordance with the
503 Contractors which do not meet the requirement in 502 requirements in the relevant equipment section of this
will be subject to special consideration in order to verify that
products satisfy the relevant requirements. standard
— general craftsmanship is acceptable.
504 The contractors shall maintain a traceable record of non-
conformities and corrective actions and make this available to c) The extent of the manufacturer’s testing shall be as re-
the DNV surveyor on request. quired by applicable sections of this standard. The testing
Guidance note: shall be performed in accordance with approved test pro-
Contractors are encouraged to obtain ISO 9000 quality system gram when required by DNV-RP-A202. Test results shall
certification through DNV accredited quality system certifica- be recorded and filed.
tion services.
Guidance note:
With respect to visual inspection, a generic description of items
505 Product survey normally emphasised, and guidelines to manufacturing survey,
are found in the DNV standards for certification.
a) A product survey shall be performed as part of the certifi-
cation process. The survey shall normally include: ---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---
DET NORSKE VERITAS

C. Survey During Installation and C 300 Function tests

Commissioning 301 Function tests are part of the Society’s verification of the
installation’s compliance with the requirements in the Rules.
C 100 General Tests as required by the Rules shall be performed in order to
101 Commissioning shall be performed as part of the classi- demonstrate that:
fication process, and shall focus on the installation on board as — the electrical system functions in accordance with ap-
well as on the functioning of the total electrical system and proved information
parts thereof. — the electrical system functions in accordance with the re-
102 When required by DNV-RP-A202, commissioning shall quirements in the Rules.
be performed in accordance with submitted procedures re-
viewed and approved by DNV prior to the commissioning. C 400 Available documentation
103 Commissioning shall be witnessed by a surveyor and is 401 At the site survey, the following documentation shall be
considered complete when all systems and equipment, includ- available for the DNV’s surveyor:
ing their control and monitoring systems are operating satis- — design documentation as required by A400
factorily. — DNV certificates for equipment required certified
C 200 Site inspections — approved ‘Hazardous area classification drawing’, see
DNV-RP-A201 standard documentation type G090
201 The site inspections shall be performed in order to eval- — for the emergency shutdown system, ‘System design phi-
uate that: losophy’, see DNV-RP-A201 standard documentation
type Z060
— the electrical installation is in accordance with the accept- — Ex certificates
ed or approved documentation — manufacturer’s declaration for non-certified equipment
— the electrical installation is in accordance with the require- that is installed in a hazardous area
ments in this standard — additional documentation where deemed necessary to as-
— the craftsmanship is acceptable. sess the installations' compliance with this standard.
DET NORSKE VERITAS

DET NORSKE VERITAS

DNV Electrical Standard

Uploaded by

Copyright:

Available Formats

DNV Electrical Standard

Uploaded by

Document Information

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

DNV Electrical Standard

Uploaded by

Copyright:

Available Formats

OFFSHORE STANDARD

DET NORSKE VERITAS

Amendments April 2002

Comments may be sent by e-mail to rules@dnv.com

Computer Typesetting (FM+SGML) by Det Norske Veritas.

CH. 1 INTRODUCTION .................................................5 J 200 Cable temperature ........................................................... 30

CH. 2 TECHNICAL PROVISIONS ...............................9 D. Mechanical and Electrical Properties ...................................35

Sec. 2 System Design...................................................... 12 E. Marking and Signboards.......................................................38

DET NORSKE VERITAS

B. Inspection and Testing.......................................................... 50 Sec. 11 Hazardous Areas Installations.......................... 71

D. Inspection and Testing.......................................................... 68 C. Survey During Installation and Commissioning...................87

DET NORSKE VERITAS

DET NORSKE VERITAS

A. Introduction 202 Other reference documents are given in Table B2.

A 100 Objectives Table B2 Normative references

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

A. Introduction 204 The requirements in this standard apply to:

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

Guidance note: voltage and frequency variations exceeding the limits

DET NORSKE VERITAS

DET NORSKE VERITAS

Duration of Duration of Duration of Duration of

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

lays (wattmetric relays), may substitute overcurrent Guidance note:

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

DET NORSKE VERITAS

---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e--- — I401- requirements for the routing of electric cables

DET NORSKE VERITAS

J 200 Cable temperature J 400 Current rating

DET NORSKE VERITAS

Table J2 Earthing connections and conductors

Conductor current rating

DET NORSKE VERITAS

DET NORSKE VERITAS

Table J6 Correction factors for ambient temperature

2) 60°C cables shall not be used in engine and boiler rooms.

DET NORSKE VERITAS

A. General Requirements — inclination 22.5° from normal level in any direction

DET NORSKE VERITAS

Table B1 Ambient air temperature ranges

C. Equipment Ratings D. Mechanical and Electrical Properties

b) All conductors, switchgear and accessories shall be of 102 Enclosures

DET NORSKE VERITAS

103 Materials 203 Anti condensation

— an alarm shall be initiated when auxiliary cooling or 302 Cable entrance

DET NORSKE VERITAS