GB/T 22669-2008Test procedures for three-phase permanent magnet synchronous machines (English PDF)

4.1.2 Frequency

4.1.2.1 Frequency deviation During the test, the difference between the power supply frequency and the specified frequency shall be within ±0.3% of the specified frequency.

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.

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).

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).

4.2.4 Rotating speed and frequency measuring instrument Tachometer reading error is within ±1r/min. The accuracy level of the frequency meter shall not be lower than level 0.1 (full scale).

4.2.5 Resistance measuring instrument The DC resistance of the winding is measured with a double-arm bridge or a single-arm bridge, or a digital micro-ohmmeter. The accuracy shall not be lower than level 0.2.

4.2.6 Temperature measuring instrument The maximum allowable error of the temperature measuring instrument is ±1°C.

4.3 Measurement requirements

4.3.1 Voltage measurement The signal line of the measuring terminal voltage shall be connected to the motor terminal. If such a connection is not allowed on site, the resulting error shall be calculated, and the reading shall be corrected. Take the arithmetic average of three-phase voltage to calculate the motor performance. The symmetry of the three-phase voltage shall meet the requirements of 4.1.1.2.

4.3.4 Torque measurement A torque tester of a suitable specification shall be used for the load test. In addition to the stall test, out-of-step torque, pull-in torque and minimum torque measurements, the nominal torque of the torque measuring instrument shall not exceed 2 times the rated torque of the tested motor.

4.3.5 Synchronous speed determination and speed measurement

4.3.6 Operating procedures In any test, when reading a series of gradually increasing or decreasing data, it shall be noted that the order of operations to increase or decrease must not be changed to avoid reversing the direction of the test.

4.4 Safety The starting current and starting torque of the self-starting three-phase permanent magnet synchronous motor are large. The test shall involve dangerous current, voltage and mechanical force, so the installation and operation of the motor under test shall be checked. Safety precautions shall be taken for all tests to ensure the smooth progress of each test. All tests shall be performed by personnel with relevant knowledge and experience, and necessary safety protection measures shall be taken.

5.1 Determination of insulation resistance

5.1.1 State of the motor at the time of measurement When measuring the insulation resistance of the motor winding, it shall be carried out under the actual cold state and hot state. During the inspection test, it is allowed to be carried out under actual cold state.

5.1.2 Selection of megohmmeter According to the rated voltage of the motor winding, select the megohmmeter according to Table 1.

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

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 (Omega) of each phase is calculated according to formula (2) to formula (7).

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.

6.3 No-load back EMF measurement No-load back EMF measurement is a unique test item for permanent magnet synchronous motor. It can be measured by anti-drag method and minimum current method. It is recommended to use the anti-drag method.

6.3.1 Anti-drag method (generator method) Use prime mover to connect mechanically with tested motor.

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.

7.2 Calculation of test results

7.2.1 Determination of stalled-rotor current and stalled-rotor torque If the maximum voltage during the stall test is in the range of 0.9UN ~ 1.1UN, the stalled-rotor current IKN and stalled-rotor torque TKN can be obtained from the stalling characteristic curve in Figure 2.

7.2.2 Torque calculation If the stall torque is not measured during stall, the stall torque TK can be calculated according to formula (14).

9.1 I2R loss of stator winding at specified temperature [see formula (15)]

9.1.1 The specified temperature thetaS is the winding temperature when converted to a reference cooling medium temperature of 25°C [see formula (16)].

9.1.2 The specified temperature thetaS is the reference temperature thetaref specified by the thermal classification of the insulation structure [see Table 2 and formula

9.2 Iron consumption PFe See 6.2.

9.3 Wind abrasion Pfw See 6.2.

9.4 Load stray loss

9.4.1 Overview Load stray loss refers to the part of the total loss that does not include the sum of stator I2R loss, iron loss and wind abrasion.

9.4.2 Input-output method for indirect measurement of load stray loss

9.4.2.1 Test method The indirect measurement method requires a rated load thermal test (see 11.7.1), load test (see 8.2) and no-load test (see 6.1). Measure the total loss, and subtract the sum of the stator loss, iron loss and wind abrasion from it to determine the load stray loss. When method B is used to determine the motor efficiency, use this method.