Siemens NCZ, 880, CZ, CGZ, CGZZ User Manual
Installation
Induction Motors/
Operation
Maintenance
Generators
Horizontal – Medallion
500, 580, 708, 788, 880 Frames
TEFC & Explosion-Proof Enclosures
Type CZ, NCZ, CGZ, CGZZ
ANIM-03522-0402
(New Issue)
©2002 Siemens Energy & Automation, Inc. All rights reserved.
Table of Contents
Page Page
TABLE OF CONTENTS 1 OPERATION 10
SAFETY PROCEDURES 2
INTRODUCTION 3
Warranty 3 Normal Operation 10
Receiving 3 Voltage/Frequency Variation 10
Handling 4 Trouble Shooting 11
Temporary Storage 4
Type Designations 4 Preventive Maintenance 13
INSTALLATION 5
Motor Dimensions 5 Corrective Maintenance 15
Location 5 Rotor Cleaning 16
Foundation 5 Stator Cleaning 16
Mounting 5 Insulation Resistance 16
Coupling of Sleeve Bearing Motors 5 Drying Insulation 16
External Wiring 6 Bearings 17
Changing Direction of Rotation 6 Bearing Lubrication 20
Alignment 6 Bearing Replacement 21
Hot Alignment 7
Vibration 8 Identification 25
Doweling 8
Force Feed Lubrication 8
Typical Motor Control Settings 9
Note - These instructions do not purport to cover all details or variations in equipment, nor to provide for every
possible contingency to be met in connection with installation, operation or maintenance. Should further
information be desired or should particular problems arise which are not covered sufficiently for the user’s
purposes, the matter should be referred to the local Siemens Sales Office. The contents of this instruction
manual shall not become part of or modify any prior or existing agreement, commitment or relationship. The
sales contract contains the entire obligation of Siemens. The warranty contained in the contract between the
parties is the sole warranty of Siemens. Any statements contained herein do not create new warranties or modify
the existing warranty.
Siemens machines are built in accordance with the latest applicable revision of the National Electric Code,
Underwriters Laboratories Standards and Procedures, and NEMA (National Electrical Manufacturers Association)
Standards. These publications and this instruction manual should be thoroughly read and understood prior to
beginning any work on this equipment.
The information contained within is intended to assist operating personnel by providing information on the general
characteristics of the purchased equipment. It does not relieve the user of the responsibility of using accepted
engineering practices in the installation, operation and maintenance of this equipment.
Should a conflict arise between the general information in this manual and the contents of the drawings and
supplementary material, the latter shall take precedence.
The illustrations in this book show typical machines. Special features deviate from those pictured.
Initial Start 10
Oil Circulating Systems 10
MAINTENANCE 13
Inspection 14
SPARE PARTS 25
MOTOR SERVICE RECORD 29
VIBRATION ANALYSIS SHEET 30
NOTES 32
- 1 -
Safety Procedures
This equipment contains hazardous voltages. Death,
serious personal injury or property damage can result
if safety instructions are not followed.
The successful and safe operation of motors and
generators is dependent upon proper handling,
installation, operation and maintenance, as well as
upon proper design and manufacture. Failure to
follow certain fundamental installation and
maintenance requirements may lead to personal injury
and the failure and loss of the motor as well as
damage to other property.
Only qualified personnel should work on or around
this equipment after becoming thoroughly familiar with
all warnings, safety notices and maintenance
procedures contained herein. Only qualified
personnel should be involved in the inspection,
maintenance and repair procedure and all plant safety
procedures must be observed.
Qualified Person: For the purpose of this manual
and product labels, a Qualified person is one who is
familiar with the installation, construction and
operation of the equipment, and the hazards involved.
In addition, he or she has the following qualifications:
a. Is trained and authorized to energize, de-energize,
clear, ground and tag circuits and equipment in
accordance with established safety practices.
b. Is trained in the proper care and use of protective
equipment, such as rubber gloves, hard hat,
safety glasses, face shields, flash clothing, etc., in
accordance with established safety practices.
c. Is trained in rendering first aid.
Danger: For the purpose of this manual and product
labels, Danger indicates an imminently hazardous
situation which, if not avoided, will result in death or
serious injury.
Warning: For the purpose of this manual and product
labels, Warning indicates a potentially hazardous
situation which, if not avoided, may result in minor or
moderate injury.
Caution: For the purpose of this manual and product
labels, Caution indicates a potentially hazardous
situation which, if not avoided, may result in minor or
moderate injury. It is also used to alert against unsafe
practices.
Motors should be installed and grounded per local and
national codes.
Do not operate this equipment in excess of the values
given on nameplate or contrary to the instructions
contained in this manual. The equipment (or a
prototype) has been factory tested and found
satisfactory for the condition for which it was sold.
Operating in excess of these conditions can cause
stresses and strains beyond design limitations.
Failure to heed this warning may result in equipment
damage and possible personal injury.
DANGER
Hazardous voltage.
Will cause death, serious injury,
electrocution or property damage.
Disconnect all power before working on
this equipment.
NOTE
Squirrel cage induction machines can be driven by
various types of prime movers. These will act as induction
generators. This instruction manual applies to both motors
and induction generators. However, for clarity reasons,
the machine will be referred to as a “motor”.
- 2 -
Introduction
DANGER
Hazardous voltage.
Will cause death, serious injury,
electrocution or property damage.
Disconnect all power before working on
this equipment.
These instructions present general recommendations
for installation, operation and maintenance of
induction motors built at the Norwood plant. If
additional information is required, contact Siemens
Energy & Automation.
Warranty
See your sales contract for warranty coverage.
Documentation of storage maintenance, alignment
and regreasing may be required for certain warranty
considerations.
Receiving
Motors are shipped in first class condition. They have
been inspected and are skidded to prevent damage
from ordinary handling during shipment.
Inspect new motors for shipping invoice. Make the
examination before removing from cars or trucks. If
damage or indication of rough handling is evident, file
a claim with the carrier at once, and notify your
Siemens sales representative.
Remove only the shipping invoice. Do not remove
tags pertaining to lubrication, operation and storage
instructions. Read and follow all instructions to insure
that no damage to motor bearings, (due to
condensation) and motor windings occurs during
storage.
Use care in handling. Dropping the motor or
otherwise imposing shock loads can cause unseen
and undetected damage to bearings. This damage
such as false brinelling of the races of anti-friction
bearings can result in early bearing failure.
If supplied, energize space heaters to help prevent
condensation within the motor enclosure.
Motors having sleeve bearings or oil lubricated
antifriction bearings are shipped WITHOUT OIL in the
bearing reservoir. These bearings and journal
surfaces are protected during shipment by a
temporary film of rust inhibiting oil or, when a motor is
supplied specifically with “provisions for oil mist
lubrication” (oil supply system furnished by the user),
the motor is shipped from the factory with grease in
the bearings.
When receiving a motor with sleeve bearings:
1. Remove shaft blocking materials.
2. Visually inspect bearing condition through sight
glass and bearing drain opening.
3. Check for moisture accumulation. Remove any
traces of oxidation before putting the motor into
service.
4. Fill bearing reservoirs to normal level with a high
grade industrial lubricating oil. See Maintenance
Section of this instruction book to determine
proper oil level.
5. Rotate the shaft a minimum of 10 complete turns
by hand to distribute oil over bearing parts. Make
sure the oil rings in each bearing rotate freely.
When receiving a motor with grease lubricated
anti-friction bearings:
Motors having grease lubricated antifriction bearings
are shipped with the bearings already lubricated and
ready for operation.
If the elapsed time from the time of shipment to the
time in which the unit is to be started is in excess of
three (3) months, regrease per the lubrication plate
mounted on the motor.
When receiving a motor with oil mist lubricated
anti-friction bearings:
1. Be sure that the motor is not stored outdoors.
2. Be sure that the oil mist lubrication is connected
and operating before starting the motor.
3. The oil mist lubrication should be in operation
within two weeks after the motor is received from
the factory.
When receiving a motor with “provisions for oil
mist lubrication”:
1. Leave the grease in the bearings if the motor is to
be stored.
2. Before operating the motor with oil mist
lubrication, disassemble the motor, and clean the
grease from bearings, end caps, and the bearing
housing cavities with a suitable solvent.
- 3 -
Introduction
WARNING
Heavy equipment.
Improper handling may cause death, serious injury or
property damage.
Check lifting devices before lifting. Use proper slings,
chains and spreaders.
Note any warning plates on motor and follow
instructions on each plate.
Handling
Lifting devices are provided for handling only. An
experienced rigger should be used to install motors.
To avoid damage, the use of spreader bars is
recommended on other than single point lifts. Lifting
devices are provided to facilitate handling with
shackles and cables. Avoid pounding or bumping
shaft, coupling or bearing parts, as shocks may
damage bearings.
NOTE WEIGHT BEFORE LIFTING. The weight is
indicated on the outline drawing. Apply tension
gradually to cables. Do not jerk or attempt to move the
unit suddenly.
Motor Weights (in pounds)
Frame Size Minimum Maximum
500 3300 5300
580 4600 6700
708 8200 9900
788 11500 13700
880 15800 19700
Temporary Storage
If the equipment is not to be installed and operated
soon after arrival, store it in a clean, dry, wellventilated place, free from vibration and rapid or wide
variations in temperature. Rotate the shaft a minimum
of 10 complete turns by hand each month to coat the
bearings with lubricant which will retard oxidation or
corrosion, and prevent possible false brinelling. If drain
plugs are provided in enclosed motors, they must be
removed periodically to drain any water accumulation
from the motor. Consider a unit in storage when:
1. It has been delivered to the job site and is awaiting
installation.
2. It has been installed but operation is delayed over
30 days pending completion of plant construction.
3. There are long (30 day) periods between operating
cycles.
4. The plant (or department) is shut down for 30 days.
NOTE
Storage requirements vary, depending on the length of
storage and the climate. For storage periods of three
months or longer or climate variations, consult Siemens
Storage Recommendations ANIM-03114. Storage
maintenance is to be documented for warranty
information.
Type Designations
The motor type designation consists of a basic letter or
letters indicating the motor enclosure type to which
other letters may be added denoting modifications.
Motor Type Motor Enclosure
CZ, NCZ, or CGZ Totally-Enclosed Fan Cooled
CGZZ
- 4 -
Explosion-Proof or
Dust-Ignition Proof
Installation
Motor Dimensions
For motors built in the frame sizes covered by this
manual, the letter dimensions have the same
definitions as established NEMA standards.
Established dimensions for these frames may be found
on catalog sheets or certified drawings.
CAUTION
Damp Location.
Can cause property damage if equipment is operated
intermittently.
Use space heaters to prevent dampness. Grease
machine fits when unit is reassembled to prevent
corrosion.
Location
Before pouring, locate foundation bolts by use of
template frame and provide secure anchorage (not
rigid). It is recommended that a fabricated steel base
be used between motor feet and foundation. See
certified drawings of motor, base, and driven unit for
exact location of foundation bolts. Allow for grouting
base when pouring. Cast the base footpads level and
in the same plane.
Mounting
Mount the motor base (if used) on foundation or other
support. Shim as required to level. Use laser or spirit
level (check two directions at 90
will be in one plane (base not warped) when base
bolts are tightened. Set motor on the base, install nuts
and tighten.
DO NOT TIGHTEN UNTIL AFTER ALIGNMENT.
o
) to insure motor feet
Select a location for the motor and driven unit that will:
1. Be clean, dry, well ventilated, properly drained, and
provide accessibility for inspection, lubrication and
maintenance.
2. Provide adequate space for motor removal without
shifting the driven unit.
3. Permit the motor to safely deliver adequate power.
Temperature rise of a standard motor is based on
operation at an altitude not higher than 3,300 feet
above sea level.
4. Avoid condensation of moisture in bearings and on
windings. Motors should not be stored or operated
in areas subject to rapid temperature changes
unless motors are energized or protected with
space heaters.
Foundation
Concrete (reinforced as required) makes the best
foundation, particularly for large motors and driven
units. In sufficient mass it provides rigid support that
minimizes deflection and vibration. It may be located
on soil, structural steel, or building floors provided the
total weight (motor, driven unit, foundation) does not
exceed the allowable bearing load of the support.
Allowable bearing loads of structural steel and floors
can be obtained from engineering handbooks. Building
codes of local communities give the recommended
allowable bearing loads for different types of soil. For
rough calculation the foundation should be
approximately 2-1/2 times total unit weight.
NOTE
Experience has shown that any base-mounted
assemblies of motor and driven units temporarily aligned
at the factory may twist during shipment. Therefore,
alignment must be checked after mounting.
Realignment is to be documented for warranty
information.
Coupling of Sleeve Bearing Motors
Sleeve bearings cannot withstand externally generated
axial thrust. Antifriction bearings are normally
designed to handle a minimum thrust. As the motor
and driven equipment get hot they may expand
towards each other and with the wrong coupling this
could produce an axial force. Therefore, the selection
of coupling is of extreme importance. If properly
installed, the following types of couplings are
considered to be free from the development of axial
thrust and may be used:
1. Laminated Metal Disk Type
2. Rubber Biscuit Type (Designed for the Speed)
Limited end float models of the following types are
available from several coupling manufacturers and
may be used by selecting the proper end float (See
“End Float – Sleeve Bearings” under Bearing
Replacement)
3. Pin and Bushing Type
4. Gear Type
- 5 -
Installation
External Wiring
DANGER
Hazardous voltage.
Will cause death, serious injury,
electrocution or property damage.
Disconnect all power before working on
this equipment.
NOTE
Before running motor, see Initial Start.
Starting and overload control devices must be matched
to motor rating. For safety or convenience they may
need to be installed some distance from the motor.
Follow the control manufacturer’s instructions to make
proper installations and connections. Observe the
following:
1. Connect electrical power supply to conform with
National Electric Code and any local regulations.
Line voltage and wire capacity must match motor
rating stamped on the nameplate.
2. With the driven equipment disconnected,
momentarily energize the motor to check rotation.
3. If motor is three-phase type, reverse rotation (if
required) by interchanging any two of the three
power leads.
Changing Direction of Rotation
Look for rotation plates usually mounted on fan
housing of the motor.
CAUTION
Excessive heat.
Motor may overheat if motor cooling fans run in the
wrong direction.
Run motor in direction shown on motor or change fans.
External fan direction must be considered if changing
direction of rotation is contemplated on motors
equipped with shaft mounted external fans. See the
following Motor Fan Direction table to identify which
motors have directional external fans. All directional
fans must be replaced with a fan designed for the
desired direction of rotation.
Motor Fan Direction
Motor Speed
Frame
500
580
708
788 DIRECTIONAL
880
3600 – 3000
RPM
1800 – 1500
RPM
NON-DIRECTIONAL
1200 RPM &
SLOWER
NOTE
It will be necessary to rebalance the rotor if the fans are
changed.
Alignment
Accurate shaft alignment between motor and driven
equipment is essential. Improper alignment may result
in vibration, bearing overloads and excessive shaft
stresses. Flexible couplings will not compensate for
excessive misalignment.
NOTE
A basic rule is to not have more than five shims in a shim
pack under any one motor foot. Thick shim packs
consisting of many thin shims will cause soft foot,
excessive vibration or twisted frame (motor foot out of
plane).
Parallel Alignment
After positioning unit for correct end float, separate the
coupling halves and mount a dial indicator rigidly on
one coupling half with the button on the cylindrical
surface of the other half. Rotate the shafts together,
and take readings at top, bottom and side positions.
Align shaft so difference between top and bottom
readings and the side readings is a maximum of
0.002 inch for a flexible coupling.
- 6 -
Installation
Angular Alignment
Hold each shaft at maximum end float. Rotate both
shafts together, and measure between matching points
at the outside diameter of the coupling faces for the
top, bottom and both sides. Use two indicators
because of possible axial shaft movement. Read
difference of variation between them.
Align shafts so that the total indicator variation does
not exceed 0.002 inch. (See Figure 1.)
NOTE
If vibration levels increase cold to hot, alignment should
be checked hot to verify that motor and driven equipment
are properly aligned at operating temperature. Adjust if
necessary.
Figure 1. Diagrams Showing Parallel and
Angular Misalignment
Foot Plane
The proper foot plane exists when adequate shims
have been installed to assure equal pressure on each
foot or corner of motor when the mounting bolts are
loose.
To determine proper foot plane:
1. Mount dial indicator on shaft to be checked so that
contact will rest on either the adjacent shaft or a
bracket from the foundation or base.
2. With mounting bolts tight and indicator set at zero,
release one bolt at the shaft extension end of the
unit and check indicator for a maximum change
of 0.001 inch.
3. If no change is indicated, retighten the bolt and
repeat the process for each of the remaining three
mounting bolts.
4. If a change is indicated, add shims under motor
foot and retighten until indicator movement is
reduced or eliminated.
NOTE
1. The foot plane is of concern for each unit of rotating
equipment. Check driven equipment if necessary.
2. Base or foundation rigidity can also affect vibration;
check for resonance in supporting structure.
3. Recheck alignment after any change in shims and
document alignment readings for warranty
information.
V-Belts
Check belt manufacturer’s recommendations for
maximum speed of sheaves and belts, minimum pitch
diameters, maximum allowable number of belts and
maximum sheave width.
When motor is ordered for V-belt drive, check motor
outline for motor manufacturer’s limits on belt pull,
sheave distance from motor, and sheave diameter.
Use only matched-belt sets. V-grooves must be in line;
sheaves must be parallel and axially aligned. Belts
must enter and leave sheaves with no side bending.
For long bearing life, the belt tension is important;
consult belt manufacturer for proper tension to suit
drive. Protect belts from grease and oil. NEVER use
belt dressing.
Hot Alignment
It is possible for the motor shaft height to change
relative to the driven equipment and this should be
compensated for during the alignment procedure.
Heat from driven equipment can also cause horizontal
misalignment.
WARNING
Rotating parts.
Can cause serious injury.
Disconnect and lock out power before working on
equipment.
If motor application is abnormal (high temperature,
extreme vibration, etc.) consult the factory for special
instructions or additional information.
- 7 -
Installation
Check for vertical alignment (parallelism) of coupled
drive as follows:
1. Operate unit until normal temperature is reached
(may require several hours).
2. Shut down motor and lock out switch.
3. Mount dial indicator as in Figure 2.
4. Rotate shaft, noting readings at 0°, 90°, 180°, and
270° (both sides, top, and bottom). If within 0.002
inch total indicator reading, or other limit specified
by the factory, unit is satisfactory for operation.
5. If not within limits, add or remove shims as
required to raise or lower motor.
6. If shims are changed for high temperature
operation, repeat alignment procedure to extent
necessary to assure proper alignment. Document
readings for warranty information.
Figure 2. Check of Vertical Alignment
Vibration
The standard unfiltered housing vibration limits
measured at no load, uncoupled, and with rigid
mounting are as follows based on the requirements of
NEMA MG1-7.8.
Speed Velocity, inches/sec peak
1200 – 3600 RPM 0.120
1000 RPM 0.105
900 RPM 0.096
750 RPM 0.079
720 RPM 0.075
600 RPM 0.063
After alignment is complete and foot mounting bolts are
tight, run motor at no load (or minimum possible).
Check for vibration. If excessive vibration exists and
the alignment is acceptable, check foot plane by
loosening one drive end-mounting bolt at a time as
detailed below. This is to be documented for warranty
information. When resiliently mounted, allowed levels
are 25% higher.
Base or foundation rigidity can also affect vibration;
check for resonance in supporting structure.
Recheck alignment after any change in shims and
document alignment readings for warranty information.
Completing Mechanical Installation
After controlling rotor end float and establishing
accurate alignment, it is recommended to drill and
ream the foundation plate and motor feet together for
dowel pins. (See Doweling).
Recheck parallel and angular alignment before bolting
the coupling together. Motor shaft should be level
within 0.03 inch after alignment.
Doweling
Doweling the motor (and driven unit) accomplishes the
following:
1. Restricts movement.
2. Eases realignment if motor is removed from base.
3. Temporarily restrains the motor, should mounting
bolts loosen.
Inserting Dowel Pins
The following procedure is recommended:
a. Check the alignment after the unit has been in
operation approximately one week. Correct as
necessary.
b. Using pre-drilled dowel holes in motor feet as
guides, drill into the mounting base.
c. Ream holes in the feet and base to the proper
diameter for tapered dowel pins. Clean out the
chips.
d. Insert dowel pins.
Force Feed Lubrication
If force feed lubrication is used, flush lubrication lines
thoroughly to make sure the lines are clean before
connecting lines to bearing housings. Be sure that
bearing cavities are filled with oil to the proper level
before starting. See motor outline drawing to
determine proper oil level. Be sure that proper oil
pressure and flow are provided by the supply system.
Verify that the oil drain flow agrees with the factory
requirements. The orientation and size of oil drain
piping supplied with the motor must not be altered. Oil
drain piping should be of the same size or larger from
the motor piping to the oil sump. Piping must slope
downward. Pressure build up in the drain line between
the oil sump and the motor bearing housing can lead to
oil leakage. Document readings for warranty
information.
- 8 -
Installation
Typical Motor Control Settings
Winding Temperature
• Class B Insulation
• Class F Insulation
Alarm
130°C
155°C
Motor Bearing Temperature
(Thermocouple or RTD’s)
• Sleeve Bearing
• Antifriction Bearing
90°C 95°C
100°C 105°C
(2)
Ground Fault
4 Amps
Primary
Circuit
Instantaneous Overcurrent
• With ½ Cycle Delay
• Without Time Delay
1.8 times Locked Rotor Amps
2.4 times Locked Rotor Amps
Maximum Voltage 110 % of Rated Voltage 10 sec.
Minimum Voltage (the minimum voltage
also applies to starting unless otherwise
specified)
90 % of Rated Voltage 10 sec.
Maximum Frequency Deviation ±5% 10 sec.
Trip
(Shutdown)
155°C
170°C
8 Amps
(2)
Primary
Circuit
Timer Trip
Setting
(1)
(2)
(2)
0.2 sec.
(2)
Maximum of Voltage Plus Frequency Deviation ±10% 10 sec.
Maximum Voltage Unbalance
Maximum Current Unbalance
(3)
1% 15 sec.
(3)
8% 15 sec.
Suggested Vibration Limits
RPM 3600 1800 1200 900 and
Slower
Shaft (mils, pk-to-pk) 3.3 3.7 4.3 5.0
Housing (in./sec.) 0.25 0.25 0.25 0.25
(1)
Maximum time at maximum condition before control device is to operate.
(2)
Increase as necessary to avoid nuisance trips.
(3)
This is the maximum deviation from the average of the three phases.
- 9 -
Operation
Initial Start
CAUTION
Do not exceed number of Siemens specified hot and
cold starts per hour.
Will cause overheating.
Allow time between starts to permit stator windings and
rotor cage to cool.
NOTE
If motor has been out of service or in storage for more
than 30 days, consult Siemens Storage
Recommendations ANIM-03114, Preparation for
Service
After installation is completed, but before motor is put
in regular service, make an initial start as follows:
1. Check that motor, starting, and control device
connections agree with wiring diagrams.
2. Check that voltage, phase, and frequency of line
circuit (power supply) agree with motor nameplate.
3. Check motor service record and tags
accompanying motor. Be certain bearings have
been properly lubricated and oil wells are filled.
See motor outline drawing to determine proper oil
level.
4. If possible, remove external load (disconnect drive)
and turn shaft by hand to assure free rotation. This
may have been done during installation procedure;
if so, and conditions have not changed, this check
may not be necessary.
5. If drive is disconnected, run motor at no load long
enough to be certain that no unusual condition
exists. Listen and monitor for excessive noise,
vibration, clicking or pounding and that oil rings are
turning if so equipped. If present, stop motor
immediately. Investigate the cause and correct
before putting motor in service.
6. If drive cannot be disconnected, interrupt the
starting cycle after motor has accelerated to low
speed. Carefully observe for unusual conditions as
motor coasts to a stop. Repeat several times if
necessary. Refer to motor’s Starting Duty
nameplate (if so equipped) or Motor Data Sheet for
recommended number of starts and cooling period
between starts.
7. When checks are satisfactory, operate at lowest
load possible and look for any unusual condition.
Increase load slowly to maximum, checking unit for
satisfactory operation.
Oil Circulating Systems
For motors with oil circulating systems, proceed as
follows before startup;
1. Fill motor reservoirs to normal level (see motor
outline drawing).
2. Follow instructions provided by the oil circulating
system supplier.
3. Put oil circulating system into operation before
starting motor.
Normal Operation
Start the motor in accordance with standard
instructions for the starting equipment used.
Sometimes the load should be reduced to the
minimum, particularly for reduced voltage starting,
and/or high inertia connected loads.
Voltage/Frequency Variation
Motors will operate successfully under the following
conditions of voltage and frequency variation, but not
necessarily in accordance with the standards
established for operating under rated conditions:
1. If the variation in voltage does not exceed
10% above or below rated voltage, with all
phases balanced. Voltage unbalance should not
exceed 1%.
2. If the variation in frequency does not exceed 5%
above or below rated frequency.
3. If the sum of the voltage and frequency variations
does not exceed 10% above or below rated
values provided the frequency variation does not
exceed 5%.
- 10 -
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