GB/T 22670-2018 PDF English
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Test procedures for converter-fed three phase cage induction motors
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GB/T 22670-2008 | English | 395 |
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GB/T 22670-2018: PDF in English (GBT 22670-2018) GB/T 22670-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.160.30
K 22
Replacing GB/T 22670-2008
Test procedures for converter-fed three phase cage
induction motors
ISSUED ON: SEPTEMBER 17, 2018
IMPLEMENTED ON: APRIL 01, 2019
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 5
1 Scope ... 6
2 Normative references ... 6
3 Terms, definitions and symbols ... 7
3.1 Terms and definitions ... 7
3.2 Symbols ... 9
4 Test requirements ... 12
4.1 Test power supply ... 12
4.2 Measuring instruments ... 13
4.3 Setting of the converter ... 14
4.4 Measurement requirements ... 15
5 Test preparation ... 17
5.1 Determination of insulation resistance ... 17
5.2 Determination of the DC terminal resistance of the winding in the initial (cold)
state ... 18
5.3 Test resistance ... 20
5.4 Winding temperature ... 20
5.5 Correct to the reference cooling medium temperature ... 21
6 No-load test ... 22
6.1 Conditions for no-load test ... 22
6.2 Determine no-load current and no-load loss ... 22
6.3 Determine the constant loss PC ... 23
6.4 Determine wind friction loss Pfw ... 23
6.5 Determine the iron loss PFe ... 24
7 Locked-rotor test ... 25
7.1 Rated frequency locked-rotor test ... 25
7.2 Breakaway torque test under converter power supply ... 28
8 Load test ... 28
8.1 Overview ... 28
8.2 Rated load test ... 29
8.3 Load characteristic curve ... 29
8.4 Determination of load characteristics of converter-fed motors ... 30
9 Determination of loss ... 31
9.1 Overview ... 31
9.2 Iron loss PFe ... 31
9.3 Wind friction loss Pfw ... 32
9.4 Load loss ... 32
9.5 Load stray loss PLL ... 33
9.6 Total loss PT ... 34
10 Determination of efficiency ... 35
10.1 Test method ... 35
10.2 Method 2-3-A: Summation method of power supply loss of converter ... 35
10.3 Method 2-3-B: Summation method of loss of specific converter power ... 38
10.4 Method 2-3-C: Input-output method ... 38
10.5 Method 2-3-D: Calorimetry ... 39
11 Thermal test ... 39
11.1 Purpose ... 39
11.2 General description ... 40
11.3 Determination of the temperature of the cooling medium in the thermal test
... 40
11.4 Determination of the cooling medium temperature at the end of test ... 41
11.5 Temperature measurement of motor windings and other parts ... 41
11.6 Thermal test method ... 42
11.7 Temperature rise ... 48
11.8 Determination of the winding’s working temperature θw under rated load ... 51
12 Determination of maximum torque ... 52
12.1 Overview ... 52
12.2 Dynamometer or calibrated DC motor method ... 52
12.3 Torque measuring instrument method ... 53
12.4 Torque tachometer method ... 53
12.5 Circular graph calculation method ... 54
12.6 Conversion of maximum torque ... 56
13 Determination of minimum torque ... 56
13.1 Overview ... 56
13.2 Dynamometer or calibrated DC motor method ... 56
13.3 Torque measuring instrument method ... 57
13.4 Torque tachometer method ... 57
13.5 Conversion of minimum torque ... 57
14 Other tests ... 58
14.1 Overspeed test ... 58
14.2 Determination of noise ... 58
14.3 Determination of vibration ... 59
14.4 Short-time over-torque test ... 59
14.5 Withstanding voltage test ... 59
14.6 Determination of the moment of inertia ... 61
14.7 Determination of shaft voltage... 63
14.8 Determination of bearing current ... 64
Appendix A (Normative) Correction method of instrument loss and error ... 66
Appendix B (Normative) Correction of dynamometer’s torque reading ... 72
Appendix C (Informative) Measurement of slip rate of induction motor ... 74
Appendix D (Informative) Linear regression analysis ... 76
Appendix E (Informative) Output voltage of converter for test ... 78
Test procedures for converter-fed three phase cage
induction motors
1 Scope
This standard specifies the test requirements, pre-test preparation, no-load test,
locked-rotor test, load test, determination of loss and efficiency, thermal test,
maximum torque and minimum torque test for converter-fed three-phase cage
induction motors.
This standard applies to converter-fed three-phase cage induction motors.
This standard does not apply to traction motors.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 755-2008 Rating and performance of rotating motor
GB/T 1032-2012 Test procedures for three-phase induction motors
GB/T 10068-2008 Mechanical vibration of certain machines with shaft
heights 56 mm and higher - Measurement, evaluation and limits of vibration
severity
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
GB/T 18039.4-2017 Electromagnetic compatibility - Environment -
Compatibility levels in industrial plants for low-frequency conducted
disturbances
GB/T 21211-2017 Equivalent loading and superposition techniques - Indirect
testing to determine temperature rise of rotating electrical machines
GB/T 25442-2010 Standard methods for determining losses and efficiency
of rotating electrical machines from tests (excluding machines for traction
vehicles)
The frequency at which the converter-fed motor is at base speed.
3.1.8
Fundamental losses
The loss of the motor at the fundamental frequency of the rated sine wave
voltage (usually 50 Hz or 60 Hz), excluding harmonics.
Note: The loss determined according to GB/T 1032-2012 is the fundamental
loss.
3.1.9
Harmonic loss
Additional loss due to non-sinusoidal voltage and current waveforms when
the converter is powered.
Note: Harmonic loss is added to the fundamental wave iron loss,
fundamental wave rotor loss, fundamental wave stator loss, stray loss; is
related to the harmonic content contained in the converter’s output value.
3.2 Symbols
The following symbols and units apply to this document.
cosφ - Power factor.
f - Frequency, in hertz (Hz).
fN - Rated frequency of the motor, in hertz (Hz).
fr - The maximum frequency of the measuring device, in hertz (Hz).
fsw - Switching frequency, in Hertz (Hz).
fMot - The fundamental frequency of the motor, in Hertz (Hz).
I - Stator line current, in ampere (A).
I0 - No-load line current, in ampere (A).
IK - Current of the locked-rotor line, in amperes (A).
IN - Rated current, in ampere (A).
K1 - The reciprocal of the temperature coefficient of resistance of the
P0 - No-load input power, in watts (W).
PK - The input power when the rotor is locked, in watts (W).
Ps - I2R loss of stator winding at test temperature, in watt (W).
Pr - I2R loss of the rotor winding at the test temperature, in watts (W).
Ps,θ - I2R loss of stator winding at specified temperature (θs), in watt (W).
Pr,θ - I2R loss of rotor winding at specified temperature (θs), in watts (W).
PTsin - The corrected total fundamental loss, in watts (W).
PTTest-converter - The corrected total fundamental loss when the converter is
powered, in watts (W).
rHL - The percentage of the loss of the harmonic voltage to the loss of the
standard sine wave voltage (rounded to an integer).
R1 - The initial end resistance of the stator winding when the temperature is
θ1, in ohms (Ω).
RN - The resistance of the stator winding end at the end of the rated load
thermal test, in ohms (Ω).
Rt - The stator winding’s end resistance measured (or obtained) at the test
temperature, in ohms (Ω).
R0 - Stator winding’s end resistance of no-load test (at each voltage point),
in ohm (Ω).
s - The slip rate.
ss - The slip rate when converted to the specified temperature (θs).
Td - Torque reading, in Newton meters (N·m).
Tc - Torque correction value, in Newton meters (N·m).
T - The corrected torque, in Newton meters (N·m).
TK - Torque of locked-rotor, in Newton meters (N·m).
Tmax - Maximum torque, in Newton meters (N·m).
Tmaxt - The maximum torque measured under the test voltage Ut, in Newton
meters (N·m).
converter.
The motor shall be powered by a suitable frequency converter and be tested
under the same carrier frequency.
4.2 Measuring instruments
For AC motors, unless otherwise specified in this standard, it shall use the
arithmetic average of the three-phase line current and line voltage.
When the test motor is loaded, the output power and other measured
fluctuations are inevitable. Therefore, several measurements covering a time
period (approximately 30 s) for each load point shall be sampled simultaneously
and the average of these values shall be used to determine the efficiency.
Considering that the frequency converter for AC motor power supply contains
harmonics and its influence on motor loss, the selected test equipment shall
have sufficient accuracy in the relevant frequency range.
The temperature measuring instrument shall have an accuracy of ±1 K.
The instrument for measuring power and current at the input of the motor shall
meet the requirements of 5.5.2 in GB/T 25442-2010. But due to the presence
of high-frequency components, it shall also meet the following additional
requirements.
When the measuring frequency is 50 Hz/60Hz, the nominal accuracy of the
power meter shall be 0.5% and above; when the measuring frequency is fr, the
nominal accuracy of the power meter shall be at least 0.5%.
fr = 10 x fsw (PWM converter output);
The selection of the measurement range shall fully satisfy the voltage and
current range of the measurement.
It is recommended to feed the current and voltage directly to the power analyzer.
If it needs an external current sensor, it must not use a traditional current sensor,
but use a bandwidth shunt or a zero-flux current sensor.
The voltage measurement loop shall be set to the average value (rectified
average measurements) instead of the effective value (r.m.s).
The bandwidth range of the current sensor and sampling channel shall be at
least 0 Hz ~ 100 kHz.
The internal filter of the digital power meter shall be turned off.
output voltage or output current;
e) The fundamental wave voltage of the motor is equal to the rated voltage
UMot = UN (50 Hz or 60 Hz) of the motor at 50 Hz or 60 Hz; the input voltage
of the test converter shall be set to make the motor reach the allowable
rated voltage, meanwhile avoid overmodulation. At the same time, the
input voltage of the converter shall not be set too high, only need to reach
the output rated value;
f) The fundamental frequency of the motor is equal to the rated frequency of
the motor fMot = fN (50 Hz, 60 Hz);
g) When the rated output power is 90 kW and below, adjust the switching
frequency fsw to 4 kHz;
h) When the rated output power is above 90 kW, adjust the switching
frequency fsw to 2 kHz.
This standard defines the output level of the test converter and establishes a
test method to verify its suitability. The input of the test converter can be a
suitable AC or DC power supply.
Shielded cables shall be used to connect the test converter and the motor. The
cable length shall be less than 100 m; the cable size shall be selected according
to the motor power.
4.3.3 Test with frequency converter of terminal equipment
When the rated voltage of the converter is higher than 1 kV, the test converter
and cable length cannot be specified. At this time, the motor, cable and
converter can only be tested as a complete electric drive system, because the
pulse mode of the high-power converter varies from manufacturer to
manufacturer; meanwhile there is also a big difference in pulse mode under no-
load and rated load.
4.4 Measurement requirements
4.4.1 Voltage measurement
The signal wire of the measuring terminal voltage shall be connected to the
motor terminal. If this connection is not allowed on site, the error caused by this
shall be calculated and the reading shall be corrected. Take the arithmetic
average of the three-phase voltage to calculate the motor performance.
The symmetry of the three-phase voltage shall meet the requirements of 4.2.1.2
in GB/T 1032-2012.
θc - The temperature of the cooling medium at the entrance during the test,
in degrees Celsius (°C);
θw - Winding temperature determined in accordance with 5.4, in degrees
Celsius (°C).
For copper windings, the temperature constant is 235. For aluminum winding,
it is 225.
For motors that use water as the primary or secondary cooling medium, the
reference temperature of water is 25 °C according to Table 4 in GB/T 755-2008.
It can also be other values according to the agreement.
6 No-load test
6.1 Conditions for no-load test
No-load test refers to a test in which the motor runs as a no-load motor and its
shaft end has no effective mechanical power output.
Before reading and recording the test data, the input power of the motor shall
be stable, that is, the difference between two consecutive readings of the input
power 30 min apart shall not be greater than 3% of the previous reading.
For water-air cooling motors, it shall cut off the water source immediately after
the thermal test (or load test).
The no-load test shall be carried out in a hot state, that is, immediately after the
thermal test or the load test.
During the inspection test, the time of no-load operation can be appropriately
shortened.
6.2 Determine no-load current and no-load loss
The test shall test the following 8 voltage points, including the rated voltage
points, namely:
- Approximately 110%, 100%, 95%, 90% of the rated voltage shall be used
as the test voltage value to determine the iron loss;
- Approximately 60%, 50%, 40%, 30% of the rated voltage shall be used as
the test voltage value to determine the wind friction loss.
The test shall be carried out as quickly as possible in the order of gradual
with the axis of the motor under test and ensure safe operation. The reading
process is to first take the reading at the maximum load; then take the reading
at the lower load.
8.2 Rated load test
Before the load test starts, it shall measure the winding resistance and
temperature of the motor under test at the ambient temperature. Apply the rated
load to the motor under test in a suitable way and run it to thermal equilibrium
(the rate of change is not more than 2 K/h). Record the following data:
P1, U, I1, T, n, f, θc, θ.
Where:
RN = R - The rated load winding resistance as determined according to 5.3,
in ohms (Ω);
θc - The temperature of the cooling medium at the entrance during the test,
in degrees Celsius (°C);
θ - The rated load winding temperature as determined in accordance with
5.4, in degrees Celsius (°C).
At the end of the load test, it shall immediately check the data offset of the
torque sensor. If the offset of the torque sensor exceeds the above allowable
tolerance, it shall be adjusted and re-measured.
8.3 Load characteristic curve
8.3.1 Overview
This test shall be carried out immediately after the end of the rated load test
while maintaining the operating temperature. If it is not feasible, before starting
to read the test data, the difference between the stator winding’s temperature
and the temperature rise θN measured by the initial rated load thermal test shall
not exceed 5 K.
Load the motor at 6 load points: About 125%, 115%, 100%, 75%, 50%, 25% of
the rated load. The test shall be carried out as quickly as possible, to reduce
the temperature change of the motor during the test.
In all test points, the frequency change of the power supply shall be less than
0.1%.
In addition to the converter, the sine wave voltage source can also be used for
these tests.
The frequency converter used for the test is called the frequency converter for
the test; its detailed definition is as shown in Appendix E. The reason why the
concept of frequency converter for test is introduced is to facilitate the
comparison of efficiency values of different motors, because the pulse mode of
the frequency converter for test is fixed and comparable. This comparison does
not apply to method 2-3-B, because the converter used in method 2-3-B is a
specific converter; its output voltage depends on the manufacturer's specific
control mode.
10.2.2 Test procedure
10.2.2.1 Test steps
The test procedures are as follows:
a) Carry out a load test under sine wave power supply at rated voltage and
rated frequency in accordance with 8.2, to determine the total loss PTsin.
b) Determine the load loss in accordance with 9.4.
c) According to 8.3, carry out load curve test under sine wave power supply
at rated voltage and rated frequency to determine the corresponding loss.
d) Carry out no-load test under sine wave power supply at rated voltage and
rated frequency in accordance with 6.2.
e) Determine the constant loss PC under sine wave power supply according
to 6.3.
f) According to 8.3, carry out the load curve test and determine the
corresponding loss under the power supply of the converter for the rated
voltage and rated frequency test.
g) In accordance with 6.2, carry out the no-load test under the power supply
of the converter for the rated voltage and rated frequency test.
h) Determine the constant loss PCC of the converter’s power supply for the
test according to 6.3.
10.2.2.2 Load-based additional harmonic loss - Load stray loss PLL and
PLLC
Through the above test, the residual loss can be determined in accordance with
9.5.1. The input power of each load point minus the output power, then minus
the stator winding’s I2R loss, iron loss, wind friction loss under the test
11.2 General description
11.2.1 Temperature measuring device
At the beginning of the thermal test, all temperature measuring devices shall be
checked to make sure that they have not increased the temperature
measurement error due to the influence of stray magnetic fields.
The motor under test shall be protected to block the influence of the airflow
generated by other machinery on the motor under test. Generally, a very slight
airflow is sufficient to cause a large deviation in the thermal test results.
Environmental conditions that cause rapid changes in the ambient air
temperature are not suitable for the temperature rise test. There shall be
enough space between the motors to allow free air circulation.
11.2.2 Temperature measurement of the rotor and other parts of a fully
enclosed motor
The temperature of the rotor and other parts of fully enclosed motor is quickly
measured by a temperature measuring device after the power is cut off.
11.3 Determination of the temperature of the cooling medium in
the thermal test
11.3.1 Air-cooled motor
For motors that use ambient air cooling, it shall carry out multi-point
measurements (2 points to 3 points) the way the cooling air enters the motor.
The measuring point is placed about 1 m ~ 2 m away from the motor, at a
position of half the height of the motor; meanwhile it shall be prevented from
the influence of external radiant heat and airflow. Take the arithmetic average
of the readings of each measuring point as the cooling medium’s temperature.
11.3.2 External cooler motor
For motors using external coolers and ducted ventilation cooling, the
temperature of the cooling medium shall be measured at the entrance of the
cooling medium into the motor.
11.3.3 Inner cooler motor
For motors which are cooled by internal coolers, the temperature of the cooling
medium shall be measured at the outlet of the cooler. For motors which are
cooled by water-cooled coolers, the water temperature shall be measured at
After the motor stops, immediately use a thermometer to measure the
temperature of the slip ring’s surface; take the highest value measured as the
slip ring’s temperature.
11.6 Thermal test method
11.6.1 Overview
The thermal test method has direct method and indirect method. It shall give
priority to the direct method. The indirect method is limited to motors of
continuous working system.
The direct thermal test shall be carried out at rated frequency, rated voltage and
rated load or nameplate current.
Indirect methods include reduced voltage load method, reduced current load
method, stator overlap frequency method and other applicable methods as
specified in GB/T 21211-2017.
11.6.2 Direct method
11.6.2.1 Motor of continuous duty (S1)
The thermal test shall be carried out continuously under the rated load, until the
temperature of each part of the motor is stable.
During the test, record the three-phase terminal voltage U, three-phase line
current I1, input power P1, frequency f, speed n or slip st, torque Tt, winding
temperature θw (measured by embedded thermometer or thermocouple
thermometer) of the tested motor once every 30 min, as well as the temperature
of the cooling medium at the inlet and outlet of the stator core, bearing, air duct,
the temperature θb of the surrounding cooling medium.
11.6.2.2 Motor of short-time duty (S2)
The test shall start from the actual cold state; the duration of the test shall be in
accordance with the rating. During the test, according to the work time, read
and record the test data every 5 min ~ 15 min. Other test requirements are the
same as 11.6.2.
11.6.2.3 Motor of intermittent cycle duty (S3)
If there are no other requirements, each working cycle during the test shall be
10 min; read and record the test data once, until the temperature of each part
of the motor reaches a thermally stable state. The temperature measurement
shall be done at the end of half of the load time of the last working cycle. In
The auxiliary power supply’s phase sequence shall be the same as the main
power supply.
U2 shall be less than U1 (usually 10% ~ 20% of U1);
Note: U2 is the voltage value to be applied to produce the rated current I1.
Figure 7 -- Test circuit diagram of stator overlap frequency method
When using the stator overlap frequency method, the phase sequence of the
main and auxiliary power supplies applied to the tested motor windings shall be
the same. The motor under test can be started separately by the main and
auxiliary power sources before wiring. If the directions of rotation are the same,
it is the same phase sequence.
During the test, first use the main power supply to start the motor under test, to
make it run at no-load at rated frequency and rated voltage. Subsequently, start
the auxiliary power unit and adjust its speed to a speed value corresponding to
a certain frequency f2. For a motor with a rated frequency of 50 Hz, f2 shall be
selected within the range of 38 Hz ~ 42 Hz. Then, put the auxiliary power
generator into excitation and adjust the excitation current, so that the stator
current of the motor under test reaches the full load current value. During the
loading process, the main power supply voltage shall be adjusted at any time,
to keep the terminal voltage of the motor under test at the rated value;
meanwhile keep the frequency f2 unchanged. The full load current value of the
tested motor at rated voltage can be determined according to the method of
11.6 in GB/T 1032-2012 or the method of 11.8 in GB/T 1032-2012. The test
requirements are the same as 11.6.2.1.
When adjusting the load of the motor under test, if the instrument pointer swings
large or the vibration of the motor under test and the test power supply
equipment is large, the auxiliary power supply voltage shall be reduced first;
then another value of frequency f2 shall be selected (adjust the speed of the
auxiliary power supply unit) for the test again.
The static variable frequency power supply that can achieve the above test
objectives can also be used for the test of stator overlap frequency method. The
static variable frequency power supply shall meet the requirements of the test
power supply (see 4.2 of GB/T 1032-2012).
11.6.3.4 Other thermal test methods
Other applicable methods specified in GB/T 21211-2017, such as induction
motor superposition method and induction motor equivalent load method.
11.6.4 Test procedure
During the test, the motor under test shall be prevented from overheating and
affecting the accuracy of the measurement. The terminal voltage of the motor
under test shall be measured on its outlet terminal.
12.3 Torque measuring instrument method
When using the torque measuring instrument method to determine the
maximum torque, it shall measure the torque-speed characteristic curve of the
motor under test. The maximum torque is obtained from the curve.
The torque-speed characteristic curve can be drawn manually after point-by-
point determination; or can be drawn directly by an automatic recorder. For
fractional horsepower and small motors, both methods can be used. The former
shall be used for medium-sized motors which use rolling bearings. When
determining the torque-speed characteristic curve point by point, the number of
points measured shall meet the needs of correctly obtaining various torques
(maximum torque, minimum torque, synchronous torque, locked-rotor torque).
Near these torques, the measuring points shall be as dense as possible.
During the test, the motor under test shall be prevented from overheating and
affecting the accuracy of the measurement. When necessary, the torque-speed
characteristic curve can be measured in sections.
When a DC motor is used as the load, the motor under test is connected to the
sensor and DC motor by a coupling. The DC motor is separately excited; its
armature is powered by an adjustable voltage and variable polarity power
supply. The rotation 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; read the torque, speed and voltage values at the same
time. Or use an automatic recorder to describe the torque-speed characteristic
curve, the relationship curve between the voltage at the motor terminal and the
speed under test. When using an automatic recorder to plot the curve, it is
recommended to measure two torque-speed characteristic curves when the
motor speed under test is rising and falling; take the average value. The drawing
time of each curve shall not be less than 15 s.
12.4 Torque tachometer method
The torque tachometer is an instrument that uses the principle that the
acceleration of the motor is proportional to the torque of the motor during the
no-load starting process, to get the torque.
This method is limited to large and medium-sized motors.
The requirements for calibration and use of DC motors are the same as in 12.2.
During the test, ......
...... Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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