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GB/T 22669-2008 (GBT22669-2008)

GB/T 22669-2008_English: PDF (GBT 22669-2008, GBT22669-2008)
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GB/T 22669-2008English545 Add to Cart 0--9 seconds. Auto-delivery Test procedures for three-phase permanent magnet synchronous machines Valid GB/T 22669-2008

BASIC DATA
Standard ID GB/T 22669-2008 (GB/T22669-2008)
Description (Translated English) Test procedures for three-phase permanent magnet synchronous machines
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard K21
Classification of International Standard 29.160.30
Word Count Estimation 33,344
Date of Issue 2008-12-31
Date of Implementation 2009-11-01
Drafting Organization Shanghai Electrical Apparatus Research Institute (Group)Co., Ltd.
Administrative Organization National Standardization Technical Committee rotary motor
Regulation (derived from) Announcement of Newly Approved National Standards No. 23 of 2008 (No. 136 overall)
Proposing organization China Electrical Equipment Industry Association
Issuing agency(ies) Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China
Summary This standard specifies the phase permanent magnet synchronous motor test methods. This standard applies to self-starting phase permanent magnet synchronous motors, variable frequency power supply static synchronous motor test can refer to the use, does not apply to a DC field winding synchronous motor.

Standards related to: GB/T 22669-2008

GB/T 22669-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.160.30
K 21
Test procedures for three-phase permanent magnet
synchronous machines
ISSUED ON: DECEMBER 31, 2008
IMPLEMENTED ON: NOVEMBER 01, 2009
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Main symbols ... 5 
4 Test requirements ... 7 
5 Test preparation ... 11 
6 No-load test ... 14 
7 Stall test ... 16 
8 Load test ... 19 
9 Determination of various losses ... 20 
10 Determination of efficiency ... 25 
11 Thermal test ... 27 
12 Measurement of out-of-step torque ... 34 
13 Determination of pull-in torque ... 35 
14 Determination of minimum torque ... 40 
15 Other tests ... 43 
16 Calculation method ... 47 
Annex A (normative) Correction of dynamometer torque reading ... 53 
Annex B (informative) Linear regression analysis ... 55 
Annex C (informative) Measurement and separation calculation method of iron
consumption and wind abrasion ... 57 
Test procedures for three-phase permanent magnet
synchronous machines
1 Scope
This Standard specifies the test procedures for three-phase permanent magnet
synchronous machines.
This Standard is applicable to self-starting three-phase permanent magnet
synchronous machines. The test for synchronous machines powered by static
variable frequency power supply may refer to use. It is not applicable to
synchronous machines with DC excitation winding.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For dated references, the subsequent
amendments (excluding corrigendum) or revisions do not apply to this Standard,
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
GB 755-2008, Rotating Electrical Machines - Rating and Performance (IEC
60034-1:2004, IDT)
GB/T 1029-2005, Test procedures for three-phase synchronous machines
GB/T 1032-2005, Test procedures for three-phase induction motors
GB 10068-2008, Mechanical vibration of certain machines with shaft heights
56 mm and higher-measurement evaluation and limits of vibration severity
(IEC 60034-14:2003, IDT)
GB/T 10069.1-2006, Measurement of airborne noise emitted by rotating
electrical machines and the noise limits - Part 1: Method for the
measurement of airborne noise emitted by rotating electrical machines (ISO
1680:1999, MOD)
GB/T 13958-2008, Test procedures for non-direct current excitation winding
synchronous motor
PS0 - No-load stray loss (W);
P0 - No-load input power (W);
PK - Input power during stall (W);
Pcu1 - I2R loss of stator winding at test temperature (W);
P0cu1 - I2R loss of stator winding under test temperature at no load (W);
Pcu1S - I2R loss of stator winding at specified temperature (θs), (W);
R1 - Initial resistance of the stator winding at a temperature of θ1 (Ω);
RN - End resistance of stator winding at the end of rated load thermal test (Ω);
Rt - Measured (or obtained) resistance of the stator winding end at the test
temperature (Ω);
RS - Stator winding end resistance (Ω) converted to a specified temperature (θs);
R0 - Stator winding end resistance of no-load test (each voltage point) (Ω);
Td - Torque reading (N·m);
Td0 - No-load (connected to the dynamometer) torque reading (N·m);
T - Corrected torque (N·m);
TK - Torque at stall (N·m);
Tp0 - Out-of-step torque measured under the test voltage UT (N·M);
Tp0N - Out-of-step torque at rated voltage (N·m);
Tmin - Minimum torque (N·m);
Tpi - Pull-in torque measured at test voltage Ut (N·m);
TpiN - Nominal pull-in torque at rated voltage (N·m);
Ta - Asynchronous torque (N·m);
TN - Permanent magnet braking torque (N·m);
U - Terminal voltage (V);
U0 - No-load test terminal voltage (V);
UK - Stalling test terminal voltage (V);
4.1.2.2 Frequency stability
No rapid changes in frequency are allowed during the test because the rapid
frequency change affects not only the motor under test, but also the output
measurement device. The frequency change during the measurement shall be
less than 0.1%.
4.2 Measuring instrument
4.2.1 Overview
The accuracy level of most instruments is usually expressed as a percentage
of full scale. Therefore, try to select low-range meters according to the actual
reading needs.
Factors that affect the accuracy of instrument measurement results:
a) Signal source load;
b) Lead wire correction;
c) Instrument range, operating conditions and calibration.
4.2.2 Electricity measuring instrument
In general, the accuracy of electricity measuring instruments shall not be less
than 0.5 (full scale, except megohmmeter). When using method B to measure
the motor efficiency, in order to maintain the accuracy and repeatability of the
test results, it is required that the accuracy level of the instrument is not less
than 0.2 (full scale).
Generally speaking, electronic instruments are versatile. Compared with
passive instruments (non-electronic type), it has a very large input impedance,
so there is no need to correct the reading due to the instrument's own losses.
But high input impedance instruments are more sensitive to interference.
Measures to reduce interference shall be taken based on practical experience.
The accuracy level of the instrument transformer used for measurement shall
not be lower than level 0.2 (full scale).
4.2.3 Torque measuring instrument
The accuracy level of torque tester (including dynamometer and sensor) for
general test should not be lower than level 0.5.
When method B (see 10.2.2) is used to determine efficiency, the accuracy level
of the torque measuring instrument shall not be lower than level 0.2 (full scale).
the insulation resistance of each phase winding to the chassis and to each other
shall be measured separately. If the three-phase winding has been connected
inside the motor and only leads to three outlets, then measure the insulation
resistance of all windings to the chassis.
After the measurement, the winding shall be discharged to ground.
5.2 Measurement of DC resistance of the winding in the initial (cold) state
5.2.1 Measurement of winding temperature in the initial state
Use a thermometer to measure the winding temperature. The motor shall be
placed indoors for a period of time before the test. The difference between the
winding temperature measured by a thermometer (or embedded thermometer)
and the cooling medium temperature shall not exceed 2K. For large and
medium-sized motors, the placement time of the thermometer shall not be less
than 15min.
5.2.2 Measurement methods
5.2.2.1 The DC resistance of the winding is measured with a double-arm bridge
or a single-arm bridge. When the resistance is 1Ω or less, it must be measured
with a double-arm bridge or an instrument of equivalent accuracy and capable
of eliminating the influence of the measuring wire and contact resistance.
5.2.2.2 When using an automatic detection device or a digital micro-ohmmeter
to measure the resistance of the winding end, the test current through the tested
winding shall not exceed 10% of its current during normal operation, and the
power-on time shall not exceed 1min. If the resistance is less than 0.01Ω, the
current through the tested winding shall not be too small.
5.2.2.3 During measurement, the rotor of the motor is stationary. The resistance
of the stator winding end shall be measured on the outlet end of the motor.
Measure 3 times for each resistance. The difference between each reading and
the average of 3 readings shall be within ±0.5% of the average. Take the
arithmetic average as the actual value of the resistance.
During the inspection test, each resistance can be measured only once.
5.2.3 If each phase winding of the motor has a beginning-end terminal to lead
out, the resistance of each phase winding shall be measured. If the three-phase
winding has been connected inside the motor and only three outlets are led out,
the resistance can be measured between every two outlets. According to the
measured resistance, the resistance value (Ω) of each phase is calculated
according to formula (2) to formula (7):
6 No-load test
6.1 Determination of no-load current and no-load loss
6.1.1 It is recommended that the no-load test be carried out after the load test
(if carried out). The input power shall be stable before reading and recording
test data. The difference between the two readings where the input power is
30min apart shall not be greater than 3% of the previous reading. For water-air
cooling motors, the water flow shall be cut off immediately after the load test.
During the inspection test, the time of no-load operation can be shortened
appropriately.
6.1.2 The voltage of the rated frequency is applied to the motor under test. The
voltage variation range gradually decreases from 125% of the rated voltage, of
which it shall include 100% rated voltage test points. As the voltage decreases,
the current gradually decreases. When the current has an inflection point, the
voltage shall continue to be reduced. Until the current value appears when the
current rises to more than 100% of the rated voltage, take 10 to 12 voltage
points (approximately evenly distributed). However, at the inflection point of the
current, the measuring point shall be properly encrypted.
At each voltage point, measure I0, U0, P0, and it shall measure θ0 or R0.
According to the proportional relationship between temperature and resistance,
use the initial resistance R1 of the winding measured before the test, the initial
temperature θ1 and the measured temperature at each point, the terminal
resistance R0 at each voltage point can be determined.
When measuring motor efficiency according to method B (see 10.2.2), θ0 or R0
must be measured at each point;
The terminal resistance of the stator winding can also be determined by a) or
b) of this article.
During the inspection test, only I0 and P0 can be measured when U0=UN.
a) The resistance value of the stator winding at each voltage point can be
determined by linear interpolation. The starting point is the resistance
value before the highest voltage point reading. The end point is the
resistance value after the lowest voltage point reading.
b) After no-load test, immediately measure the resistance of the stator
winding end. Use this resistance as the resistance value at each voltage
point.
6.2 Determination of the sum of iron consumption PFe and wind abrasion
drives the motor under test as a generator running at no load at synchronous
speed. Measure the outlet voltage Uab, Ubc, Uca of the tested motor separately.
Take the average value as the no-load back EMF line voltage value. Record the
temperature and ambient temperature of the stator core of the motor at this time.
6.3.2 Minimum current method
The motor runs stably under no-load operation at rated voltage and rated
frequency. Adjust the external terminal voltage of the motor to minimize the no-
load current. The applied terminal voltage at this time can be approximated as
the no-load back EMF of the motor. Respectively measure the outlet voltage
Uab, Ubc, Uca of the tested motor. Take the average value as the approximate
value of the no-load back EMF line voltage value. Record the temperature and
ambient temperature of the motor core at this time.
7 Stall test
7.1 Measurement of current, torque and power during stall
Stalling test is conducted when the motor is close to the actual cold state.
Before the test, the rotor position corresponding to the maximum stalled-rotor
current and the minimum stalled-rotor torque shall be determined with a low
voltage in advance as much as possible. During the test, the rotor shall be
blocked.
The rotor oscillates greatly when the motor is stalled. It shall consider measures
to reduce fluctuations. During the test, it can first adjust the power supply
voltage to less than 20% of the rated value. Connect to the motor under test.
Maintain the rated frequency. Increase the power supply voltage as soon as
possible. After electrical stabilization, quickly read stable readings of voltage,
current, input power and torque simultaneously. To avoid overheating of the
motor, the test must be carried out quickly.
7.1.1 Measure the characteristic curve of stalled rotor, that is, the relationship
between the current IK, torque TK and the applied voltage UK during stalling, as
shown in Figure 2.
the reading is to first read the reading at the maximum load, then read the
reading at the lower load.
8.2 Rated voltage load test
The test shall be conducted at rated voltage and rated frequency. Before
starting to read the test data, the difference between the stator winding
temperature and the temperature measured during the rated load thermal test
shall not exceed 5°C.
Load the motor with suitable equipment (such as dynamometer, accompanying
test motor). Use a torque measuring instrument that meets the requirements of
4.2.3 to measure the torque.
Load the motor at 6 load points. 4 load points are roughly evenly distributed
between not less than 25% ~ 100% of rated load (including 100% of rated load).
Choose 2 load points between 100% but not more than 150% of rated load.
The process of loading the motor starts from the maximum load. Gradually
reduce to the minimum load in sequence. The test shall be carried out as quickly
as possible to reduce the temperature change of the motor during the test.
At each load point, measure U, I1, P1, Td, f (or n), θt (or Rt) and θf.
It is recommended to use a temperature sensor (embedded at the end of the
stator coil) to measure the temperature of the winding.
When measuring the motor efficiency according to method B, it must measure
θt or Rt at each point.
The resistance value of the stator winding at each load point can also be
determined by the method specified in a) or b) below.
a) The resistance value at each load point of 100% rated load and above is
the resistance value before the maximum load point reading. The
resistance value of each point of less than 100% rated load is determined
according to the linear relationship with the load. The starting point is the
resistance value at 100% rated load. The end point is the resistance value
after the minimum load reading.
b) After the load test, immediately measure the resistance of the stator
winding end. Use this resistance as the resistance value of each load point.
9 Determination of various losses
9.1 I2R loss of stator winding at specified temperature [see formula (15)]
calculate efficiency.
10.2.1.1 Test process
During the test, the motor under test shall reach thermal stability under the rated
load. Carry out the load test according to the method specified in 8.2.
10.2.1.2 Calculation format
Calculate the motor performance according to format A given in 16.1.
10.2.2 Method B: Loss analysis and indirect measurement of stray loss by
input-output method
Measure electric power (including instrument transformer). The accuracy level
of the instrument used for torque and speed shall meet the requirements of
4.2.2, 4.2.3, 4.2.4 and 4.2.5. This is particularly important for measuring the
efficiency of the motor by using method B.
10.2.2.1 Test procedures
Method B test is mainly composed of three parts: rated load thermal test (see
11.7.1), load test (see 8.2) and no-load test (see 6.1). It is recommended to
conduct thermal test first, which is conducive to the stability of motor friction
loss. Immediately conduct the load test after. Conduct the no-load test at last.
If the test cannot be carried out continuously in the above order, the motor must
reach the thermal stability of the rated load thermal test before the load test.
10.2.2.1.1 Load test
The test shall be conducted in accordance with the requirements of 8.2 and
relevant data shall be measured. Before starting to record the test data, the
difference between the stator winding temperature and the maximum
temperature recorded in the rated load thermal test shall not exceed 5°C. The
test shall be carried out as quickly as possible to reduce the temperature
change of the motor during the test.
According to the method proposed in Annex A, obtain the torque reading
correction value kd. The dynamometer or torque sensor shall be calibrated in
the same direction as the load test.
10.2.2.1.2 No-load test
See 6.1 for the no-load test. Before starting to record the test data, the motor
shall be run without load until the input power is stable (see 6.1).
10.2.2.2 Determination of various losses
Since the small error in measuring resistance shall cause a large error in
determining the temperature, the instrument required in 4.2.5 shall be used to
measure the winding resistance. If possible, the second instrument can be used
for inspection. The initial resistance and the resistance at the end of the test
shall be measured by using the same instrument.
11.3.3 Embedded thermometer method
This method measures the temperature with a thermocouple or resistance
thermometer installed in the motor.
Specially designed meters shall be used with resistance thermometers, so as
to prevent the introduction of significant errors or damage to the instrument due
to the heating of the resistance thermometer during measurement. Many
common resistive measurement devices may not be suitable because there
may be a considerable current flowing through the resistance element during
measurement.
11.4 Temperature reading
11.4.1 General instructions
The following clauses introduce 3 methods of temperature measurement, used
to measure the temperature of the winding of the motor, the stator core, the
cooling medium entering, and the cooling medium discharged after being
heated. Each measurement method has its own characteristics, suitable for
measuring the temperature of specific parts of the motor.
11.4.2 Thermometer method
During the thermal test, use the thermometer method (see 11.3.1) to measure
the temperature of the following components. If required, it can be measured
after shutdown.
a) Stator coil, at least in 2 places;
b) Stator core, for large and medium-sized motors, at least in 2 places;
c) Ambient temperature;
d) The air discharged from the base or exhaust vent or the internal cooling
medium discharged from the motor with a circulating cooling system to the
inlet of the cooler;
e) Machine base;
f) Bearing (if it belongs to motor parts).
11.6.1 Determination of winding temperature
The temperature of the motor winding is measured by the resistance method.
If the motor has a buried thermometer, use a thermometer.
11.6.2 Determination of core temperature
The core temperature is measured with a temperature detector or thermometer.
For large and medium-sized motors, the thermometer shall be no less than 2.
Take the highest value as the core temperature.
11.6.3 Determination of bearing temperature
Bearing temperature is measured with a thermometer. For sliding bearings, the
thermometer is placed in the temperature measuring hole of the bearing or near
the surface of the bearing pad. For rolling bearings, the thermometer is placed
closest to the outer ring of the bearing.
11.7 Thermal test method
The thermal test method shall use the direct load method.
11.7.1 Direct load method
The thermal test of the direct load method shall be performed at the rated
frequency, rated voltage, rated power or nameplate current.
During the test, the tested motor shall maintain the rated load until the
temperature rise of each part of the motor reaches the thermal stable state.
During the test, record the voltage U, current I1, input power P1, frequency f,
speed n, torque Td, winding temperature θN and the temperature of stator core,
bearing, air duct inlet and outlet cooling medium and surrounding cooling
medium θa of the tested motor every 30min.
During the test, measures shall be taken to minimize changes in the
temperature of the cooling medium.
If the temperature rise of the winding is determined by extrapolation, the
resistance of the winding shall be measured immediately after the motor is
turned off. And determine the resistance RN after the rated load thermal test
according to 11.7.5. For motors that use external coolers and ducted cooling,
the supply of cooling medium shall be stopped while the motor is disconnected
from the power supply.
If the temperature rise test is performed with the nameplate current, the winding
temperature rise ΔθN(K) corresponding to the rated power is converted
according to the following method [see formula (30) and formula (31)]:
12 Measurement of out-of-step torque
12.1 Overview
Out-of-step torque is measured by direct load method. During the test, a torque
measuring instrument, brake, dynamometer or calibrated DC generator with
uniformly adjustable load shall be used as the load. The motor under test shall
be connected to a power supply that is actually balanced at the rated frequency
and rated voltage. Adjust the tested motor to run under rated load. Then
gradually increase the load of the tested motor to make it out of step. Torque
value measured from torque measuring instrument, brake or dynamometer at
the moment of out-of-step shall be the out-of-step torque of the tested motor.
a) Torque measuring instrument method;
b) Brake, dynamometer or corrected DC motor method.
When using the above test methods, the measurement shall be carried out at
the rated frequency and rated voltage. If the test voltage cannot reach the rated
voltage, the out-of-step torque value shall be converted according to 12.4.
12.2 Torque measuring instrument method
When measuring the out-of-step torque with the torque measuring instrument
method, an automatic recorder can be used to directly describe the torque-
speed characteristic curve and the relationship between the voltage of the
tested motor terminal and the speed. The out-of-step torque is obtained from
the curve.
During the test, the motor under test shall be prevented from overheating and
affecting the accuracy of the measurement.
When the DC motor is used as the load, the motor under test is coupled with
the sensor and the DC motor with a coupling. The DC motor is excited
separately, and its armature is powered by an adjustable voltage and variable
polarity power supply. The motor under test shall be connected to a power
supply that is actually balanced at the rated frequency and rated voltage. The
direction of the tested motor and the DC motor shall be consistent. Adjust the
power supply voltage of the DC motor. Gradually increase the load of the tested
motor to make it out of step. The torque value at the moment of out-of-step is
the out-of-step torque Tp0.
12.3 Brake, dynamometer or corrected DC motor method
If the load of the tested motor is a brake or a dynamometer, the out-of-step
torque can be read on the brake or dynamometer at the instant of out-of-step.
If the point where the slip rate is 0.05 in the test is not easy to establish
accurately, then the load of the motor under test can be adjusted to make the
slip rate around 0.05 and take 4~5 points. Calculate the torque as above. Then
make a curve of torque to slip. Determine the torque value from the curve when
the slip rate is 0.05.
Calculate the characteristic curve of torque and speed by torque measuring
instrument. Obtain the nominal pull-in torque value from the point where s=0.05
on the curve.
13.1.2 Acceleration method
The tested motor is connected to the rated frequency. The voltage can be
adjusted on the actual balanced power supply. Start the motor as a no-load
motor. The power supply voltage shall be adjusted to enable the motor from
30%nN to nN in about 1.5 min. During acceleration, the power supply voltage
and frequency remain unchanged. If the minimum voltage at which the motor
can start from a standstill does not meet the above requirements, then the
power supply voltage shall be further reduced until the above requirements are
met. But at this time the motor shall use other methods to help start (for example,
use crane to help start or start with higher voltage first, then cut off the power
supply to slow down the motor. When the motor speed drops below 30% nN,
add the required voltage to test). In the range of 30%nN~80%nN speed,
measure the speed every 5s~10s and record the time. It shall be recorded every
3s~5s within the range of 80%nN~100%nN. During the test, pay attention to
whether the motor is overheated.
When using a fast recorder test, the time to accelerate to full value can be faster
than the above regulations.
Make the curve of speed versus time from the test data, as shown in Figure 4.
Find the slope dn/dt of the curve at 95%nN. The slope can be determined by the
following method. Take point a at 95%nN on the curve as the center. Take two
points b and c equidistant from a on the curve (the ordinate of point b shall not
exceed nN). The difference between the ordinate of these two points is Δn. The
difference between the abscissa is Δt. The slope of the curve is Δn/Δt.
at this speed without increasing speed). Disconnect the power supply of the
motor under test. Adjust the dynamometer or correct the power supply voltage
of the DC motor so that its speed is about 1/3 of the intermediate speed. Then,
close the power supply of the motor under test, quickly adjust the power supply
voltage (or excitation current) of the dynamometer or correct the power supply
voltage of the DC motor. Until the dynamometer's dynamometer reading or the
armature current of the dc motor has a minimum value, read this value and the
terminal voltage of the motor under test. When using a corrected DC motor, it
is necessary to read the speed value at the same time.
When the dynamometer is used as the load, when the dynamometer and the
motor under test have the same direction and the minimum torque cannot be
measured, the polarity of the dynamometer power supply voltage can be
changed, and the test can be performed.
During the test, the motor under test shall be prevented from overheating.
14.3 Torque measuring instrument method
When measuring the minimum torque with the torque measuring instrument
method, the torque-speed characteristic curve of the motor under test must be
measured. The minimum torque is obtained from the curve.
The torque speed characteristic curve can be manually drawn after point-by-
point measurement, or directly drawn by automatic recorder. When measuring
the torque and speed curve point by point, the measured points shall meet the
requirements of correctly calculating various torques (locked torque, minimum
torque, pull-in torque, out-of-step torque). Near these torques, the
measurement points shall be as close as possible.
During the test, the motor under test shall be prevented from overheating and
affecting the accuracy of the measurement. If necessary, the torque speed
characteristic curve can be measured in sections.
When the DC motor is used as the load, the motor under test is connected to
the sensor and the DC motor with a coupling. The DC motor is excited
separately, and its armature is powered by an adjustable voltage and variable
polarity power supply. The direction of the tested motor and the DC motor shall
be consistent. Adjust the power supply voltage of the DC motor. Gradually
increase the load of the motor under test. And read torque, speed and voltage
at the same time. Or use an automatic recorder to describe the torque-speed
characteristic curve and the relationship between the terminal voltage of the
motor under test and the speed, see Figure 5.
Rotor oscillations are particularly severe when the permanent magnet
synchronous motor is close to stall. Therefore, the load inertia of the connection
15.2 Determination of noise
The noise is measured according to GB/T 1006.9-1-2006.
15.3 Determination of vibration
The vibration is measured according to GB 10068-2008.
15.4 Short-term over-torque test
Short-term over-torque test shall be carried out at rated voltage and rated
frequency.
During the test, the motor gradually increases the load in a hot state, so that its
torque reaches the over torque value specified in GB 755-2008 or various types
of motor standards. The duration is 15s.
If it is limited to equipment, it is allowed to use the stator current instead of the
torque measurement during the test. At this time, the stator current value shall
be equal to 1.1 times the over torque multiple times the rated current value.
15.5 Withstand voltage test
Test power frequency is power frequency. The voltage waveform shall be as
sinusoidal as possible.
15.5.1 Test requirements
a) The withstand voltage test is conducted when the motor is stationary.
Before the test, the insulation resistance of the winding shall be measured.
If over-speed and short-time over-torque tests are required, this test shall
be carried out after these tests. During the type test, the test shall also be
performed after the thermal test is close to the thermal state of the motor.
b) During the test, the voltage should be applied between the winding and
the chassis. At this time, other windings that are not involved in the test
shall be connected to the core and the chassis. For motors with a rated
voltage above 1kV, if both ends of each phase are led out separately, then
each phase shall be tested one by one.
c) The test transformer sha...
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