INDUCTION DRILLING MOTOR

INSTRUCTION AND SERVICE

MANUAL

Model DM27 Series

Drawwork, Rotary Table, Mud Pumps
And Top Drives

Manual Cannot Change without

Prior Approval of Notified Body

REFERENCE REFERENCE DESCRIPTION

Model DM27 Series Drawwork, Rotary Table, Mud Pumps and
RIG/PLANT Top Drives
This document contains proprietary and confidential information National Oilwell Varco
ADDITIONAL CODE SDRL CODE TOTAL PGS which belongs to National Oilwell Varco; it is loaned for limited 500 Industrial Blvd.
purposes only and remains the property of National Oilwell Varco.
REMARKS Reproduction, in whole or in part; or use of this design or Sugar Land, TX 77478-2898
distribution of this information to others is not permitted without the United States
MAIN TAG NUMBER DISCIPLINE
express written consent of National Oilwell Varco. This document is Phone: +1 (281) 240 6111
to be returned to National Oilwell Varco upon request and in any
event upon completion of the use for which it was loaned. Fax +1 (281) 274-0426
CLIENT PO NUMBER  National Oilwell Varco
DOCUMENT NUMBER REV
CLIENT DOCUMENT NUMBER
210-DM27A 02
Client Document Number

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REVISION HISTORY

02 18.06.2012 Revision Change S.L.M. N.J. B.M.

01 30.06.2011 First Issue S.L.M. J.P. C.W.
Rev Date (dd.mm.yyyy) Reason for issue Prepared Checked Approved

CHANGE DESCRIPTION

Revision Change Description

01 First Issue
02 Update Nameplate Reference, Spare Parts & Connection Reference

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TABLE OF CONTENTS
1 INTRODUCTION ............................................................................................................... 5
1.1 Introduction ............................................................................................................. 5
2 GENERAL DESCRIPTION ............................................................................................... 7
2.1 Construction ............................................................................................................. 7
2.2 Bearings…………………………………………………………………………………... 8
2.3 Accessories ............................................................................................................. 8
2.4 Variable – Frequency Operation.............................................................................. 8
2.5 Technical Information ............................................................................................. 9
2.6 Additional Information .......................................................................................... 10
3 SAFETY INFORMATION AND WARNINGS .................................................................. 11
3.1 Grounding Instructions.......................................................................................... 12
3.2 Lifting .................................................................................................................... 14
4 INSTALLATION .............................................................................................................. 15
4.1 Receiving .............................................................................................................. 17
4.2 Unpacking and Storage ........................................................................................ 17
4.3 Inspection ............................................................................................................. 18
4.4 Location ................................................................................................................ 18
4.5 Foundation ............................................................................................................ 19
4.6 Alignment .............................................................................................................. 19
4.7 Power Connections............................................................................................... 24
5 START-UP PROCEDURE AND OPERATION ............................................................... 25
5.1 Pre-Operation Equipment Check .......................................................................... 25
6 SCHEDULED MAINTENANCE....................................................................................... 26
6.1 Covers and Seals ................................................................................................. 26
6.2 Power Cable Inspection ........................................................................................ 27
6.3 Insulation Resistance Test .................................................................................... 27
6.4 Motor Mounting Hardware .................................................................................... 28
6.5 Bearing Maintenance ............................................................................................ 28
6.6 Cleaning the Motor ............................................................................................... 30
6.7 Drying Procedure .................................................................................................. 31

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6.8 Methods of Drying................................................................................................. 31

6.9 Maintain Record.................................................................................................... 32
7 RECOMMENDED SPARE PARTS LIST ........................................................................ 33

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1 INTRODUCTION

1.1 Introduction

This publication provides the basic information to install, operate, and maintain motor
maintenance. This includes inspection, cleaning and lubrication requirements for
National Oilwell Varco drill motor family. These motors are designed for use in horizontal
and vertical applications. Specifically for drawworks, rotary table, mud pumps and top
drives. Refer to (Figure 1.1) for typical appearance.

Figure 1.1

Protection of the motor is the responsibility of the end user and must be in accordance
with the instructions in this manual. In addition, the end user must follow all
requirements of Machinery Directive for Safe Installations.

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Depending on the installation, the end user or final installer must guard the exposed
motor shaft in accordance with the requirements of the Machinery Directive 2006/42/EC.

This motor is a component for installation in machinery as defined in the Machinery

Directive 2006/42/EC. Commissioning is prohibited until conformity of the end product
with this directive has been established with regard to all local safety and installation
rules.

The noise level of the motor appears on the Data Sheets contained in the Drawing and
Data Package manual. When the sound level exceeds 85 dB(A), ear protection must be
worn in the vicinity of the motor.

NOTE:
1. All special tooling is to ship with motor.

2. Metric units must appear on the motor dimensional data.

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2 GENERAL DESCRIPTION

The motor is an alternating current squirrel cage induction motor of forced ventilated
construction designed for use with Variable Frequency Drives only. The construction of
this motor results in a totally enclosed, forced air-cooled machine (IP44) with IP56
terminal boxes. The motor requires a minimum of 2800 SCFM to be provided to the inlet
of the motor. The motor is provided with inlet air openings for duct connections and
supplied with an exhaust ducting. Exhaust ducting must remain in place for certification.

The stator and coil assembly is an integral part of the frame with the stator laminations
welded directly to the frame structure. The motor frame is equipped with removable end
frames which provide support for the bearings.

2.1 Construction

A 3-phase induction motor has two main parts: A stationary stator and a revolving rotor.
The rotor is separated from the stator by an air gap. The stator consists of a steel frame
that encloses and secures the laminated stator core. The stator core is made from thin
laminations and coated insulated to minimize hot spots and stack losses, stacked to
form a hollow cylinder. At the air gap, along the inner circumference of the laminations,
the stator laminations have evenly spaced slots that contain the stator winding.

The rotor is also made up of punched laminations carefully stacked to create openings
(slots) along the air gap. Copper rotor bars are inserted into the slots and connected
(short circuited) at each end by copper end rings. Bars are swaged into the rotor slot to
avoid movement and as a counter-measure against sparking and vibration. The rotor
forms a cage and is referred to as a “squirrel cage” rotor.

The entire rotor assembly, consist of stacked laminations, bars and end rings. All
components are secured onto the shaft. The shaft along with the rotor assembly rotates
and is supported by bearings mounted at each end. The shaft has a tapered shaft
extension for ease hub installation for coupling. For detailed information, see the
Outline and Mounting drawing included in the Drawing and Data Package of this
manual.

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2.2 Bearings

National Oilwell Varco motors are constructed with a two bearing configuration system.
The two types of bearing styles are ball/ball or ball/cylindrical (roller bearing) which is
grease lubricated and equipped with specially constructed lip seals. The non drive end
is insulated and the rotating shaft assembly is supported by a deep groove ball bearing.
The drive end of the rotating shaft assembly is supported by a fixed ball bearing or a
cylindrical roller bearing - see motor outline for specific bearing application.

Bearing lubrication is required at 3,000 hour intervals and bearing replacement is

required at 25,000 hours of operation. See “Scheduled Maintenance” Section for
proper lubrication and factory installed lubricant specifications.

2.3 Accessories

National Oilwell Varco motors are available with accessories such as speed encoders
and other components required for motor application. The motors require a forced-air
ventilation system. Refer to the motor accessory description provided in the Drawing
and Data Package of this manual for specific information regarding the accessories and
configuration of the motor. (Motor Certification does not include accessories.)
If speed encoders are mounted on the NDE side of shaft, special precaution should be
taken to avoid circulating currents using appropriate insulated hardware for installation.

2.4 Variable – Frequency Operation

This motor is designed to be operated with (powered by) a Variable Frequency Drive.
The list of approved drives is listed in the current ATEX Certificate. If there is any
concerns about any approved Variable Frequency Drive please contact the
manufacture, National Oilwell Varco, Sugar Land, Texas.

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2.5 Technical Information

Motor Model Series DM27

Motor performance is based on the following operating parameters:

600V 690V Drive System Voltage

1150 1229 Horsepower
560 640 Volts
1.0 1.0 Service Factor
1100 1100 Amperes (Max)
40.60 43.25 Hertz Nominal
3 3 Phase
800 855 RPM Nominal

The motor is an alternating current induction motor forced ventilated construction with a
completely installed air supply system.

The bearing housings are equipped with seals and includes provisions for re-lubrication
during operation. Each bearing is equipped with one 100 ohm platinum resistive
temperature device for monitoring temperature. The temperature of the bearings should
be monitored during operation. The alarm point should be set at 90°C and shut down
initiated at 100°C.

The stator of the motor is equipped with six 100 ohm platinum resistive temperature
devices (embedded between the coils of the stator) with 3 additional spares. The stator
coils embedded in the laminated core receive a Global VPI of non-hygroscopic resin.
The stator insulation system is Class H. For proper insulation protection, the RTD relays
should be set for alarm at 185°C max, and shutdown at 190°C max. The winding RTD
leads are internally shielded in the terminal block of motor terminal box.

The power cables connect to the motor (through the gland plate of the connection box)
must be sealed or attached using the appropriate fitting. This fitting must meet
(minimum) the motor nameplate rating and protection or be rated to operate in more
severe conditions.

Note: The cable connection rating must adhere to Section 4.7 of this manual.

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2.6 Additional Information

The motor windings are supplied with RTD’s two per phase and one per bearing. It is
essential for the customer to wire the motor RTD’s from the terminal box to the
temperature monitoring device. It is critical to check the connections at the RTD
terminals for tightness – see motor outline drawing for RTD terminations details.

Shielded cable should be used on temperature monitoring equipment with the shield
grounded only at the monitor end.

Space Heaters are provided in the motor frame and should be energized continuously
during motor storage. (Note: During start-up and operation of the motor, the heaters
should be de-energized.) See motor outline drawing for space heater wire diagram and
power information.

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3 SAFETY INFORMATION AND WARNINGS

Dangerous voltages are present in the motor and peripheral components. ALL POWER
TO THE MOTOR AND COMPONENTS MUST BE TURNED OFF AND LOCKED OUT
BEFORE ACCESSING. FAILURE TO DO SO COULD RESULT IN SERIOUS INJURY
OR DEATH. Warning labels appear on all access covers advising of the potential shock
hazards (Figures 3.1 and 3.2). Access should be limited to qualified and trained
personnel equipped with proper safety equipment and clothing. The motors shall be
grounded in accordance with all local and national codes to reduce the potential hazard
of shock from incidental contact. Insure motor is properly grounded before energized.

When in the vicinity of a running motor, ear protection should be worn as the sound level
may exceed 85 dB(A).

Amperes for sizing the power supply cable appears in the general motor data and the
nameplate of the motor (See Drawing and Data Package of this manual for nameplate
information). The size and insulation requirement of the supply cabling is dependent on
the location and application of the motor. All supply cables shall be installed and
grounded in accordance with local, national, or agency codes governing the application.

Figure 3.1

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Figure 3.2

3.1 Grounding Instructions

Grounding motor frames is required to safeguard personnel from electric shock and to
protect the machine itself in the event of an insulation failure in the machine or installation.

WARNING!
FAILURE TO PROPERLY GROUND ELECTRICAL EQUIPMENT MAY EXPOSE
PERSONNEL TO A POTENTIALLY HAZARDOUS CONDITION IN WHICH SERIOUS
OR FATAL INJURY FROM ELECTRICAL SHOCK IS POSSIBLE.

Grounding conductors must be provided between the machine frame and the supporting
structure. The purpose for this is to avoid hazardous potential voltage difference between
the machine frame and the adjacent surface on which a person may be standing while
contacting the machine surface.

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Figure 3.3 - Grounding pads provided on motor frame and terminal box

Grounding of the motor and its auxiliary equipment or boxes are compulsory and must
be performed in accordance with current regulations. The motor frame provides a
grounding pad as provision for a connection with 3/8 – 16 bolting.

Main connection box and auxiliary boxes provided with motor are surged and grounded,
tested and must not be removed.

Before installing the terminal lug on the ground cable, remove paint, rust, and oil from all
surfaces to which the cables are attached. Bolt lug securely to the surfaces and torque
the bolt or nut to 20 lb. ft. (27.12 Nm). After installation, protect the ground pad bolt,
washer, and cable lug connection from corrosion by applying a rust inhibitor on the
exposed components.

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3.2 Lifting
Safe lifting and handling of the motor is important to prevent potential damage to the
motor and/or serious injury to personnel. The motor is equipped with lifting provisions
and should only be handled using these devices. Refer to the figure for typical locations
of lifting provisions and motor data sheet for weight of the motor.

Figure 3.4

WARNING!
Appropriate safety equipment should be worn by qualified personnel when installing and
maintaining the motor. Heed all warning signs and labels to insure the motor is isolated
from all power sources before performing any service work or cleaning.

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4 INSTALLATION
WARNING!
INSTALLATION SHOULD BE IN ACCORDANCE WITH THE SPECIAL CONDITIONS
LISTED ON THE ATEX CERTIFICATION AND DECLARATION OF CONFORMITY.
MACHINES ACCESSIBLE TO THE PUBLIC SHOULD BE FURTHER GUARDED BY
SCREENING, GUARD RAILS, ETC., TO PREVENT THE PERSON FROM COMING IN
CONTACT WITH THE EQUIPMENT. FAILURE TO OBSERVE THESE PRECAUTIONS
MAY RESULT IN SERIOUS INJURY OR DEATH.

The machine is intended to be suitable for operation in typical oil well drilling industry rig
environments, including, but not limited to offshore platforms and mobile drilling units.
For other applications and/or special environmental conditions, please contact National
Oilwell Varco Power Generation Group, Sugar Land, TX to determine suitability.

The nameplate shown below in Figure 4.1 only applies to motors requiring ATEX
certification.

For Reference Only

Figure 4.1

The motor has been tested and approved with the Variable Frequency Drives (VFD)
listed in the ATEX CERTIFICATION.

For all approved Variable Frequency Drives refer to the ATEX CERTIFICATE.

1. The End User must provide the protection for the motor in accordance with the
instructions in this Manual provided by National Oilwell Varco and the reference
on the ATEX certificate.
2. This motor requires the following peripheral measures to maintain the safe
temperatures of increased safety “e” protection to a maximum T3 (200°C) surface
temperature.

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a.) Motor requires thermal protection.

b.) This motor requires forced air cooling during operation. The cooling forced
air shall be at least 2800 SCFM and at a temperature not exceeding the
ambient temperature.
3. Do not open motor covers when energized. All components must be de-
energized before opening access covers or enclosure covers.
4. Use only the variable frequency drive designated on the certificate and within the
voltage ratings described. Not intended for across-the-line start.
5. If additional wiring modification is required and or adding accessories to the motor
prior to installation and use. These additional elements are not included in this
certification and the user of this certificate must ensure the final installation
conforms to the relevant ATEX requirements.

RTD’s supplied with the motor are to be connected to intrinsically safe circuits to meet
compliance of the Ex e certification for operation in hazardous locations

Variable Frequency Operation Considerations

A motor fed by a Variable Frequency Drive power source will exhibit increased
temperature as compared to a motor operated on a pure sine-wave voltage form due to
the affects of the harmonic frequencies produced by the drive. The amount of increase
in losses and increase in motor temperatures is dependent on the harmonic
characteristics of the drive feeding the motor and the design of the motor.

The motors have been specifically designed and tested for satisfactory operation with
the Variable Frequency Drive type(s) listed on the motor nameplate and/or this manual.
The operating program of the drive could affect the temperature of the motor if it is not
done properly. The motor parameters for programming proper operation of the Variable
Frequency Drive are provided in motor data sheet and nameplate. Refer to the drive
system instruction publications for controls and indicators.

WARNING!
ANY CHANGES TO THE PROGRAMMING OF THE VARIABLE FREQUENCY DRIVE
COULD ADVERSELY AFFECT THE TEMPERATURE AND PROTECTION OF THE
MOTOR AND INVALIDATE THE SUITABILITY OF THE INCREASED SAFETY “e”
APPLICATION OF THE MOTOR IN A POTENTIALLY EXPLOSIVE ATMOSPHERE.

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4.1 Receiving

The motor is skidded and secure prepared for shipment and can withstand most shocks
and rough handling incurred during transit. Before accepting shipment from the
transportation company, examine the motor carefully to determine if any damage has
occurred during shipment. Unpack the unit and carefully examine the frame and sheet
metal for damage. Inspect for the presence of moisture and make certain no foreign
material such as packing, loose fasteners or dirt have fallen into the motor during
transportation and unpacking. If transportation damage is noted, determine the extent of
the damage, and immediately notify the transportation company claims office and National
Oilwell Varco in Sugar Land, Texas. Be sure to provide complete and accurate details
when reporting damage.

4.2 Unpacking and Storage

If the motor is received during cold weather, allow the unit to stabilize to room temperature
before removing the protective covering and packing material. This precaution will
minimize the condensation of moisture on the cold surfaces and the possibility of early
malfunctions resulting from wet windings or other insulating materials.

4.2.1 Unpacking

Unpack the motor with care to avoid damage to the unit. Connect an overhead crane, or
suitable lifting device, to all lifting points provided on the motor, lift the unit from the
shipping skid and place it in its mounting location. Avoid manhandling the motor and
never apply a lifting force to structural points other than those provided for that purpose.

CAUTION!
Failure to use lifting points and extreme care when moving the motor can result in
damage to the motor, other objects, or personal injury.

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4.2.2 Storage

If the motor is not to be installed in its operating location as soon as received, it should be
stored in a clean, dry area not subject to sudden changes in temperature and humidity.
Storage at normal room temperature is recommended. The motor should be covered to
protect it against dust, dirt, moisture and other airborne material while in storage. Consult
with National Oilwell Varco for storage recommendations when the motor cannot be stored
in a temperature and humidity controlled area or storage for a period of more than six
months is anticipated.

Space heaters, when provided in the motor frame, should be energized continuously
during storage of motor, but should be de-energized at time of installation and start-up.
Details of space heater power and connections may appear in the Drawing and Data
Package of this manual.

4.3 Inspection

Before installing the motor, it is recommended the unit be thoroughly inspected for
indications of damage or potential malfunctions. Carefully examine the exterior surfaces of
the motor for deep scratches, dents, damaged guards, loose or missing bolts, screws and
other attaching parts. Remove the exhaust hoods and access covers from the motor and
inspect the rotor and stator and other internal components for loose or damaged windings
and lead wires, loosely mounted components, and the presence of moisture or other
foreign material. Remove all shipping materials such as blocks, straps, tapes, rubber
packing, paper or other material used to restrict movement of the rotor during shipment.
Use low pressure compressed air, 25 PSI maximum, to blow out all packing residue and
dust from the interior of the motor. Turn the rotor by hand to make certain it rotates
smoothly and without binding.

4.4 Location

The motor can be installed in any clean, dry, well ventilated area which allows a
sufficient unobstructed flow of coolant air and provides sufficient accessibility for
operation and maintenance of the unit. Avoid locations which would subject the motor to
excessive moisture, dust, steam, or fumes from acids, alkalies or other corrosive
chemicals. If such exposure cannot be avoided, a strict periodic inspection and
maintenance schedule must be established.

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4.5 Foundation

The foundation or support for the motor must be rigid, level and of ample size and
strength to support the weight of the motor and withstand the motor foundation reaction
loads. The foundation must also be adequately designed to maintain coupling alignment
between the motor and driven load. It is very important that the foundation is designed in
such a manner as to not have any resonant operating frequencies at or near the
operating speed, or at a multiple of the operating speed of the unit.

4.6 Alignment

There are three basic types of alignment: parallel, angular, and axial. Misalignment can
be parallel, angular, axial, or any combination of the three. An explanation of each type
of misalignment follows.

4.6.1 Parallel

Parallel (radial) misalignment, Figure 4.2, is the difference in position of the center of
rotation of one shaft with respect to the center of rotation of the other shaft.

Figure 4.2 – Parallel Misalignment

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4.6.2 Angular

Angular (face) misalignment, Figure 4.3, is the angle one shaft centerline makes with the
other shaft centerline at the coupling connection.

Figure 4.3 - Angular Misalignment

4.6.3 Axial

Axial misalignment, Figure 4.4, is the relationship of the motor rotor to the motor stator.

Figure 4.4 - Axial Misalignment

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4.6.4 Alignment Considerations

The motor and driven-load should be located and leveled on the mounting base. Care
should be taken to eliminate “Soft Foot Condition”.
Soft Foot is the condition where the motor does not sit flat on its’ base and only three of
the four mounting points support the motor. When the fourth point is clamped down the
motor frame or mounting skid is distorted causing possible vibration or erroneous
alignment information. Soft Foot can be corrected by loosening each mounting point one
at a time, measuring the relative movement with a dial indicator, and shimming under
the foot to eliminate that relative movement. The relative movement should not exceed
0.005 inch. Shims with burrs on the edges can contribute to the soft foot condition.

4.6.5 Alignment Measurement

Rotate the indicators so that they are at the top location. It is suggested to zero the dial
indicator when at the top location for convenience. The coupling hub should be marked
at 0, 90, 180, and 270 degrees and a stationary reference mark placed or identified on
the equipment so that when the shafts are rotated, they can be indexed through 90
degree increments. Both shafts should be rotated together.

An easy way to record the measurements is to draw two circles on paper, one for
parallel and one for angular measurements. Also, record the radius of the measurement
point for the angular (face) measurement.

Figure 4.5 - Dial Indicator Setup

Rotate the shafts one-quarter turn and record the dial indicator measurements. Take
measurements at 90, 180, 270 and 360 (0) degrees locations. The dial indicators should
read zero when returning to the top (starting or 0 degree) location. If the indicators do
not read zero, disregard the measurements and repeat the procedure. Figure 4.3 and
4.4 shows a typical set of measurements and their corresponding Total Indicator

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Readings (TIR). Once these measurements are recorded, the relationship of the
measurements to the allowable misalignment in Table 1 can be determined by
subtracting measurements in each plane to find the Total Indicator Reading (TIR) value.

Figure 4.6 - Typical Parallel (Radial) Measurements

For Reference Only

Figure 4.7 - Typical Angular (Face) Misalignment

For Reference Only
Table 1 lists maximum allowable parallel and angular misalignment for two bearing
NATIONAL OILWELL VARCO motors. After the initial measurements are taken, the
motor must be aligned and shimmed to achieve the acceptable alignment
measurements.

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Allowable Misalignment

Speed Axial
(RPM)

(inch)

0 to 900 0.002 0.0005 in. / in. radius to ± 1/32

measurement point
901 to 1200 0.002 0.0005 in. / in. radius to ± 1/32
measurement point
Above 1201 0.001 0.0005 in. / in. radius to ± 1/64
measurement point

Table 1 - Maximum Allowable Shaft Misalignment for Two Bearing Motors

It is a good practice to first correct the parallel and angular misalignment in the
horizontal plane. Jack screws attached to the skid can be used to adjust the location in
the horizontal plane. Once corrections are made, a new set of alignment measurements
should be taken. If the alignment in the horizontal plane is within limits, then proceed
with correction in the vertical plane. The proper corrections can be determined through
careful evaluations of the measurements. Corrections for parallel and angular
misalignment may be made together. After any corrections are made in the alignment,
new measurements must be taken for all three forms of misalignment.

Once alignment is completed, it is a good practice to record measurements for future

reference.

4.6.6 Coupling

The machine must be connected to the driven equipment with flexible couplings. (pin
coupling, gear coupling)

CAUTION!
Careful alignment of machines, when using either solid (rigid) or flexible couplings, is
essential to prevent excessive vibration, hot bearings, or shaft failures.

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Couplings must be properly sized to be capable of driving maximum machine torque.

Interference fits should be used between motor shaft and coupling.

4.7 Power Connections

Machine maximum amperes for sizing the power supply cables appear on the outline
drawing and data sheets contained in this manual. The size and insulation requirements
of the cables depend on the location and application of the motor. The power supply
cables to the motor must be installed and grounded to the local electric codes
requirements.

Check the connections of the main power leads from the variable frequency drive to the
terminal leads at the motor. Proper spacing must be maintained. Motor leads are
marked T1-T2-T3 for a three (3) lead machine and (EU Nomenclature U, V, W).
Normally, motors are supplied as three (3) lead machines with neutral leads connected
together internally to the motor. Outline drawings and connection diagrams in this
manual will indicate how the connections are to be made. For motors fed by Variable
Frequency Drives, the neutral if present is not grounded. Ensure that the line voltage
and frequency correspond to that shown on the motor nameplate.

If machine is exposed to humidity and foreign particles it is highly recommended to

properly insulate the motor lead bus bars inside main terminal box.

Particular care must be exercised connecting the starting device phase leads to the
motor. The leads must have the proper sequence applied by the Variable Frequency
Drive to obtain the desired motor rotation. (For example, phase sequence L1-L2-L3 of
the power supply connected to motor terminals T1-T2-T3 will give clockwise rotation
facing the non-drive end of the motor). Reversing (L1) & (L3) of the power supply leads
will produce rotation in the opposite direction.

Connections of main power supply cables to the motor must be in accordance with IEC
60034-8.

NOTE!
If there is any doubt about rotation and phasing, the motor can be “bumped” to indicate
the direction of rotation by momentarily energizing the motor. A minimum of two people
should check this, one at the motor and one at the starting device with good visual/oral
communication via radio. For the purpose of “bumping” the motor to determine rotation,
the starting device should energize the motor only as long as it takes to cause the motor
to “break-away” and begin to rotate. If the rotation is incorrect, remove power from
motor and allow motor to coast to a stop. Reverse L1 & L3 of the power supply
connections to the motor to correct the rotation.

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5 START-UP PROCEDURE AND OPERATION

5.1 Pre-Operation Equipment Check

After the motor and control equipment are completely installed and wired, but before
operating the unit for the first time, perform the following inspections.

1. Check all interconnecting wiring against the connection diagrams supplied with
the motor.
2. Make certain no foreign objects are lodged in the motor, all guards, and safety
devices are securely in place. Remove all materials not required for operation
from the vicinity of all rotating equipment.
3. If the motor has been subjected to extreme dampness during shipment or
storage, it may be necessary to dry out the winding prior to placing the unit into
operation. Refer to the “Schedule Maintenance” Section of this manual for the
proper procedure for testing winding insulation resistance and for drying the
winding insulation. A motor being placed into service after being subjected to
very low temperatures should be slowly warmed to prevent condensation.
Heaters must be turned off prior to motor start-up.
4. Insure mounting hardware has been properly installed and where applicable,
secured to a proper foundation or framework.
5. Insure the ground connection is properly installed.
6. Insure main power leads are properly connected per the Wiring Diagrams
contained in the Outline and Mounting drawing in the Drawing and Data Package
of this manual. Re-install all covers prior to operating the motor.
7. Verify RTD’s for monitoring winding and bearing temperatures are functioning.

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6 SCHEDULED MAINTENANCE

Periodic maintenance is required to ensure successful motor operation. The following

procedures detail the Scheduled Maintenance. The motor bearing housings are
designed for periodic lubrication.

Note: In order to maintain ATEX approval, only National Oilwell Varco original parts shall
be used as replacement parts.

6.1 Covers and Seals

WARNING!
HAZARDOUS VOLTAGES ARE PRESENT IN THIS EQUIPMENT. FOLLOW LOCAL
SHUTDOWN PROCEDURES TO ENSURE POWER IS NOT APPLIED TO THE
MACHINE BEFORE PERFORMING ANY MAINTENANCE. FAILURE TO DO SO MAY
RESULT IN INJURY OR DEATH.

1. REMOVE ALL POWER FROM THE MACHINE BEFORE ATTEMPTING

MAINTENANCE PROCEDURES.
2. Clean the outside of the machine, the ventilation filters and remove the inspection
covers.

WARNING!
WHEN USING COMPRESSED AIR FOR CLEANING PURPOSES, FLYING DEBRIS
AND PARTICLES MAY PRESENT A HAZARD TO PERSONNEL IN THE IMMEDIATE
AREA. PERSONNEL SHOULD BE PROVIDED WITH, AND TRAINED IN THE USE
OF, PROTECTIVE EQUIPMENT AS SPECIFIED BY APPLICABLE FEDERAL AND
STATE SAFETY REGULATIONS. FAILURE TO DO SO MAY RESULT IN INJURY OR
DEATH.

3. Use clean, dry compressed air (25 psi maximum) and blow the dirt and dust from
the interior of the machine.
4. Check exterior covers to ensure the gaskets are intact. Replace gaskets if
missing, broken, deformed, or hardened.
5. Inspect the motor for loose or damaged windings, cracked, burned or broken
insulation, loose mounting components, loose hold down bolts, and the presence
of moisture or other foreign material.
6. Inspect the area surrounding the bearings for signs of excessive leakage of
grease. Lubricate the bearings in accordance with the recommendations set forth
in the bearing lubrication instructions provided in Section 6.5 of this manual. Use
only the recommended grade of grease.

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7. Inspect the lead wires and control device wiring for cracked or damaged
insulation and loose terminals.

6.2 Power Cable Inspection

During inspection of the power cables and associated hardware, replace any
components that are damaged. Inspect the power cable for:

1. Inspect the cable terminals for discoloration from heat, arc damage, cracks, or
fractures. Replace terminals and/or cable if damage is found.
2. Ensure terminal connections are tight and arcing is not present.
3. Inspect cable insulation for cracked, worn, cut, bubbled, or burnt insulation.
Replace the cable if damage is found.
4. Check cable connection bushings and mounting hardware (such as cable cleats).
Replace damaged or missing hardware.
5. Check the ground cable connection to the motor frame. Ensure the connection is
tight on the ground stud.

6.3 Insulation Resistance Test

Lower than normal insulation resistance can be an indication that conductive

contaminant is present on the motor winding circuit (Stator winding / connections, joints
and bus bars). The contamination may be humidity (water), salts, dust or virtually any
dirt saturated with moisture. These contaminants develop a conductive path that can
produce shorts or grounds and eventually failure. National Oilwell Varco recommends
checking insulation resistance every six months, record data and monitoring its trends.

The insulation condition of the motor winding and cables can be determined by an
insulation resistance test (megger). When the high voltage of the insulation resistance
test instrument is applied to the power components of the motor circuit, a high ohm
reading indicates good insulation quality. Low ohm readings indicate insulation
breakdown, moisture/debris contamination, or carbon tracking. To test the winding
insulation with an insulation resistance tester:
1. Ensure all components in the power circuit are not affected by an insulation
resistance test. Prior to measuring ensure power cables are disconnected from
the drive system.
2. Connect a lead from the insulation resistance tester to the motor terminal T1.
3. Connect the second lead of the insulation resistance tester to a cleaned ground
connection. Use stator frame as ground.
4. Apply a 500 DC volt to test winding insulation resistance. For a minimum of 60
seconds.
5. If the reading is above 2 megohms, the power circuit insulation is satisfactory, it is

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safe to start and operate the machine.

6. If the reading is below 2 megohms, this is an indication that winding insulation is
inadequate to operate the machine and further investigation is required.
Perform the following procedures to attempt to raise the megger insulation
resistance reading:
a. Check motor main cables inside terminal box for cracks, scuffed, or open
insulation. Repair or replace the cables if damage is found.
b. Water or dirt/debris contamination may be adversely affecting the winding
insulation resistance reading. If not visual contamination is present, then
cleaning process should not be initiated unless is clear evidence. Remove
covers and inspect for evidence of moisture or water inside the machine.
Refer to cleaning and drying procedures of this manual if evidence of
water or moisture is present.

6.4 Motor Mounting Hardware

Check the motor mounting bolts, nuts, and associated hardware. Ensure the hardware
is not missing or loose. Replace missing hardware and tighten loose bolts.

6.5 Bearing Maintenance

6.5.1 Grease Specifications

A high quality NGLI #3 grease is recommended, with the following minimum physical
properties:
Appearance Smooth Property
Value of
ASTM test
Thickener Lithium N/A
Worked Penetration – 60 Strokes at 25°C 220-240 D 217
Estimated Operating Temp. Range °C -40°C to 135°C D 4693
Bomb Oxidation, 99°C – kPa Drop in 100 4.2 D 942
hours
Dropping Point °C 195°C D 2265
Wheel Bearing Leakage gms 1.1 D 4290
Base Oil Viscosity, cSt at 40°C 93 D 445
Flash Point 212°C N/A

The motor is supplied with and it is recommended that service be maintained with:
Shell Oil Company - Cyprina - Product Code 504-538

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6.5.2 Lubrication Maintenance

The motor is factory furnished with the bearing properly prepared with the correct
amount of grease for initial operation. The bearing housing is equipped with a grease
zerk and a grease vent to facilitate servicing of grease to the bearing. During preventive
maintenance inspections, the grease seal area and adjacent shaft area should be
inspected for signs of excessive leakage. If excessive leakage is present, the seals
should be replaced.

It is recommended that the following re-lubrication interval and amount be adhered to for
proper bearing operation and life.

NOV Part No. Bearings Grease Quantity Interval

1030-20-0076 6330M 100-105 Grams* Every 3000 hours of operation
or 3 months
1030-14-0004 BCI-1330 100-105 Grams* Every 3000 hours of operation
or 3 months
10502005-001 6326 100-105 Grams* Every 3000 hours of operation
or 3 months
10090160-001 6320 50-55 Grams* Every 3000 hours of operation
or 3 months
1030-08-0113 BBI-3039 50-55 Grams* Every 3000 hours of operation
or 3 months

*A typical industrial grease gun pumps approximately one gram of grease for every
stroke of the gun.

The recommendations for typical installations may need to be adjusted for specific
applications. In applications for standby use, the amount of grease may need to be
reduced to avoid over greasing. In applications of extreme temperatures or higher than
normal air born contaminates, the amount or frequency of lubrication may need to
increase. Please consult National Oilwell Varco in Sugar Land, Texas if you have
questions concerning a specific application. If over greasing occurs, the motor can
be run as long as the temperature of the bearing is closely monitored and the unit is shut
down when it reaches the alarm point.

Should it become necessary to remove the bearing from the motor, it should be
thoroughly inspected for wear or damage prior to re-installation, and replaced if
necessary. The seals of the bearing housing should also be inspected for wear or
damage and replaced if necessary. When re-installing the bearing, the bearing should
be hand packed with grease and the bearing housings should be packed to 1/2 to 2/3
full with grease. Care should be taken to insure that no foreign material is allowed into
the grease, bearing or bearing housing.

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Bearing design life is in excess of any operational requirements, but it is recommended

to replace all motor bearing every 25,000 operating hours.

6.6 Cleaning the Motor

Cleaning the motor is essential to long-term motor life. When the drilling motor is
removed from its machinery, accumulated dirt and oil buildup can be removed. The
external motor surfaces can be cleaned by steam cleaning. The internal motor
components should not be sprayed with a steam cleaner. To clean the motor:

1. Clean the external motor surfaces only when the drilling motor is removed from its
machinery and power is removed from the motor.

WARNING!
PERSONNEL PERFORMING CLEANING PROCEDURES MUST WEAR PROTECTIVE
CLOTHING, GLOVES, AND EYE PROTECTION. FOLLOW LOCAL PRACTICES AND
PROCEDURES FOR CLEANING. FAILURE TO DO SO MAY RESULT IN INJURY OR
DEATH.

WARNING!
ALKALI AND CHLORINATED HYDROCARBON CLEANING SOLUTIONS SHOULD
NOT BE USED FOR CLEANING DRILL MOTORS DUE TO THE ADVERSE AFFECTS
ON MOTOR INSULATION. USE OF THESE SOLUTIONS MAY CAUSE MOTOR
FAILURE OR REDUCED MOTOR LIFE.

WARNING!
DO NOT SPRAY THE INTERNAL COMPONENTS OF THE MOTOR WITH A STEAM
CLEANER. MOISTURE CONTAMINATION MAY CAUSE MOTOR FAILURE OR
REDUCED MOTOR LIFE.

2. Cover the motor air inlet and outlet with heavy plastic and tape in place. Ensure
the interior motor components are protected from spray during cleaning.
3. Steam clean the external surfaces of the motor. Do not direct the spray at motor
openings or the plastic covers.
4. When steam cleaning is complete, let excess fluid drain from the motor.
5. Remove plastic covers or protective covers and tape from the motor.

Clean the inside of the motor by using a vacuum cleaner or dry low pressure
compressed air, 25 PSI maximum, to remove any accumulation of dirt, dust or other
gritty particles. Stubborn deposits of grease, oil or similar substances on the metal
components that are located away and clear of the windings and insulating components

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may be cleaned using a clean cloth moistened with a nonflammable solvent.

WARNING!
UNDER NO CIRCUMSTANCES SHOULD THE SOLVENT OR SOLVENT MOISTENED
CLOTH BE ALLOWED TO CONTACT THE WINDINGS OR INSULATING
COMPONENTS.

Deposits of grease, oil or similar substances on the winding or insulating components

should only be removed with a clean dry shop cloth. Consult with National Oilwell Varco
in Sugar Land, Texas if the winding or insulating components are contaminated to an
extent where wiping with a cloth will not remove the contaminants. See Drying
Procedure.

6.7 Drying Procedure

If the motor has been subjected to extreme dampness during shipment, storage, or
cleaning, a procedure may be required to thoroughly dry all windings.

If the stator insulation resistance measures less than 2 megohms, the machine must be
dried out until at least the minimum recommended resistance value is obtained. The
drying-out process can be accomplished by applying either external or internal heat as
necessary to obtain an end-winding temperature of 75°C (167°F) by thermometer.

6.8 Methods of Drying

The easiest and most convenient method of drying out a motor consists of placing the
complete, or partially disassembled, machine in an oven. External heat also can be
applied by placing space heaters beneath the motor so as to obtain an even distribution
of heat along the length of the unit. Care must be taken to provide adequate air
circulation during the drying-out process to insure a complete and thorough job.

CAUTION!
The temperature of the motor should be raised slowly to avoid building up excessive
vapor or gas pressure, which could prove harmful to the insulation. Do not exceed a
temperature rise of 10°C (18°F) per hour.

CAUTION!
Do not hurry the drying-out process. Never permit the temperature of the motor to
exceed the maximum allowable temperature rise marked on the data plate.

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6.9 Maintain Record

It is advisable to maintain a record of the insulation resistance and humidity during

measurements for each motor. The measurements, taken at maintenance intervals, will
provide a means of detecting a gradual deterioration of the winding insulation. Such
records should list the prevailing site conditions, such as the test voltages, ambient
temperature and humidity, at the time of each test since these conditions will affect the
results.

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7 RECOMMENDED SPARE PARTS LIST

This manual is generic for the DM27 Series product line. Please refer to the motor
nameplate for Model Number and match that information to corresponding spare parts
list.

“HN” MODEL
DESCRIPTION *NOV PART NO.
RTD, Bearing Probe, 100 Ω 6550-25-0029
Bearing, DE 6330M Type 1030-20-0076
Bearing, NDE 6320 Type 10090160-001
Seal NDE 10090180-001
Heater 6550-10-0069
Seals, DE 10511454-001
Seals, Sleeve DE 10509096-001

“HL” MODEL
DESCRIPTION *NOV PART NO.
RTD, Bearing Probe, 100 Ω 6550-25-0029
Bearing, DE BCI 1330 Type 1030-14-0004
Bearing, NDE 6320 Type 10090160-001
Seals, NDE 10090180-001
Heater 6550-10-0069
Seals, DE 10511454-001
Seals, Sleeve DE 10509096-001

*NOV – National Oilwell Varco’s Part Number

Replacement parts or accessories for this motor are available through National Oilwell
Varco in Sugar Land, TX.

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