A test and evaluation method for train traction motor stator insulation

Abstract

The present invention relates to train traction motor insulation, and more particularly to train traction motor stator insulation, and more particularly to a method for testing and evaluating train traction motor stator insulation. To address the problems of existing train traction motor stator insulation testing and evaluation methods, which cannot timely evaluate the traction motor stator insulation status, have a long testing and evaluation time, and are prone to causing secondary damage to the train traction motor stator insulation, a method for testing and evaluating train traction motor stator insulation is provided. The method performs multiple rounds of insulation resistance testing on the traction motor after it has returned to the depot. During each round of insulation resistance testing, the stator winding resistance value is tested to calculate the temperature of the motor stator winding. The stator insulation status of the traction motor is evaluated based on the insulation resistance variation trend. This method can significantly reduce the manpower, material resources, and time costs consumed during the maintenance process, and significantly improve the operating efficiency of the traction motor.

Description

Technical Field

[0001] The present invention relates to the insulation of a train traction motor, in particular to the insulation of a train traction motor stator, and specifically to a test and evaluation method for the insulation of a train traction motor stator. Background Art

[0002] Traction motors have complex structures, and failures caused by stator insulation failure are the primary type of stator failure, accounting for approximately 30%-40%. Consequently, extensive research has been conducted both domestically and internationally on the inspection and testing of motor insulation, particularly stator insulation. Existing techniques analyze insulation condition by returning the motor to the factory for insulation performance testing. For example, CRRC Dalian Locomotive and Rolling Stock Co., Ltd. published "Research on the Insulation Performance of the C6 Repair of the YJ85A / A1 Traction Motor" in 2019 in its Rail Vehicles publication. This article determined the insulation condition of returned motors by testing their insulation resistance, polarization index, dielectric loss factor, and partial discharge. However, this method requires the motor to reach the appropriate maintenance level before it can be disassembled and returned to the factory or repair depot for testing. This prevents timely assessment of the traction motor's stator insulation condition. Furthermore, the entire process is not only time-consuming, but also prone to secondary damage, such as bumps, during disassembly, which reduces the motor's service life and insulation life. Summary of the Invention

[0003] In order to solve the problems that the existing test and evaluation method for the stator insulation of a train traction motor cannot timely evaluate the insulation status of the traction motor stator, the test and evaluation time is long, and the stator insulation of the train traction motor is easily damaged, the present invention provides a new test and evaluation method for the stator insulation of a train traction motor.

[0004] The present invention is implemented by adopting the following technical solution: A method for testing and evaluating the stator insulation of a train traction motor, comprising the following steps: 1) after the train returns to the depot and stops, an insulation resistance tester is used to test and record the stator insulation resistance value of each motor (how to test and how to connect are common knowledge of those skilled in the art, that is, one end of the insulation resistance tester is connected to any one of the three-phase power supplies of the motor, and the other end of the insulation resistance tester is connected to the corresponding motor casing), and at the same time, a DC low resistance tester is used to test and record the stator winding resistance value of each motor (how to test and how to connect are common knowledge of those skilled in the art, that is, the two ends of the DC low resistance tester are connected to any two-phase power supplies of the motor), and the formula t is used to calculate the stator winding resistance of each motor. N =R N (t0+235) / R0-235 calculate and record the stator winding temperature t of the Nth test N , where t0 is the stator winding reference temperature, R0 is the stator winding resistance at the reference temperature, R N1) Test the stator winding resistance value for the Nth time; 2) Multiple times (multiple times means two or more times, so step 1) should be performed at least three times, that is, step 1) once + step 2) multiple times) Repeat step 1) until the stator winding temperature t N The temperature is 50-60℃, and the order of the motors tested each time is the same as the order of the motors tested in the previous test. 3) Judgment standard: If the stator insulation resistance value of a motor shows an increasing trend as the stator winding temperature decreases, then the stator insulation condition of the motor is judged to be good; if the stator insulation resistance value of a motor does not show an increasing trend as the stator winding temperature decreases, then the stator insulation condition of the motor is judged to be abnormal.

[0005] The beneficial effects of the present invention are as follows: Compared with the existing technology, the test and evaluation method in the present invention is simple to operate and can be used for testing without removing the motor from the train. The motor stator insulation status is evaluated based on the change trend of the motor stator insulation resistance value, which can greatly reduce the manpower, material and time costs consumed in the disassembly and maintenance process, greatly improve the working efficiency of the traction motor, and provide a reliable data basis for the maintenance of rail transit traction motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a graph showing a trend of insulation resistance values ​​of a motor stator according to the first embodiment;

[0007] Figure 2 This is a graph showing the variation trend of the insulation resistance value of the motor stator in the second specific embodiment. DETAILED DESCRIPTION

[0008] A method for testing and evaluating the stator insulation of a train traction motor comprises the following steps: 1) after the train returns to the depot and stops, an insulation resistance tester is used to test and record the stator insulation resistance value of each motor (how to test and how to connect the wires are common knowledge among those skilled in the art, i.e., one end of the insulation resistance tester is connected to any one of the three-phase power supplies of the motor, and the other end of the insulation resistance tester is connected to the corresponding motor casing); and simultaneously, a DC low-resistance tester is used to test and record the stator winding resistance value of each motor (how to test and how to connect the wires are common knowledge among those skilled in the art, i.e., the two ends of the DC low-resistance tester are connected to any two-phase power supplies of the motor), and the stator winding resistance value of each motor is calculated by the formula t N =R N (t0+235) / R0-235 calculate and record the stator winding temperature t of the Nth test N , where t0 is the stator winding reference temperature, R0 is the stator winding resistance at the reference temperature, R N 2) Repeat step 1) until the stator winding temperature t NThe stator winding temperature of a motor is 50-60°C, and the order of the motors tested each time is the same as that of the previous test. A certain time interval is set between two adjacent tests so that the stator winding temperature difference between the two adjacent tests is 10-20°C. 3) Judgment standard: If the stator insulation resistance value of a motor shows an increasing trend as the stator winding temperature decreases, the stator insulation condition of the motor is judged to be good; if the stator insulation resistance value of a motor does not show an increasing trend as the stator winding temperature decreases, the stator insulation condition of the motor is judged to be abnormal.

[0009] During implementation, the stator winding temperature must be above 100°C when performing step 1) for the first time. This ensures that the motor is fully dry after operation, eliminates the impact of humidity on test results, and improves assessment accuracy. A certain interval should be set between tests to ensure that the stator winding temperature difference between the two tests is 10°C to 20°C, reducing the number of tests while ensuring data reliability. Each time the motor stator insulation resistance is tested using an insulation resistance tester, the stator insulation resistance should be measured after 60 seconds. If the motor stator insulation is determined to be in good condition in step 3), perform step 1) again before the train leaves the depot and record the ambient temperature and relative humidity. Under normal conditions, the motor stator insulation resistance tends to decrease due to humidity. Based on the degree of decrease, assess the degree of surface contamination of the motor stator winding (how to assess this is common knowledge for those skilled in the art) to facilitate timely repairs.

[0010] The following two examples illustrate the evaluation method:

[0011] Example 1: Conducting 4-round insulation resistance tests on a city's subway motor:

[0012] 1) After the train returned to the depot and stopped, the first test was conducted. The highest temperature of all motor stator windings in the train was 100.91°C, the lowest temperature was 86.1°C, the maximum motor stator insulation resistance was 12.9GΩ, and the minimum motor stator insulation resistance was 4.28GΩ (see the specific changes in motor stator insulation resistance values ​​for details). Figure 1 The first round of testing changes the trend line);

[0013] 2) After 40 minutes, the second round of testing was carried out. The maximum temperature of all motor stator windings in the train was 86.02°C and the minimum temperature was 71.36°C, which was about 15°C lower than the first test. The maximum insulation resistance was 13.1GΩ and the minimum was 5.23GΩ (see the specific changes in motor stator insulation resistance values ​​for details). Figure 1 The second round of testing changes the trend line);

[0014] 3) After 60 minutes, the third round of testing was conducted. The highest temperature of all motor stator windings in the train was 67.00°C and the lowest temperature was 52.88°C, which was about 18°C ​​lower than the second test. The maximum motor stator insulation resistance value was 11GΩ and the minimum motor stator insulation resistance value was 5.69GΩ (see the specific changes in motor stator insulation resistance values ​​for details). Figure 1 The third round of testing changes the trend line);

[0015] 4) 12 hours later, the fourth round of testing was conducted before the train left the depot. The highest temperature of all motor stator windings in the train was 42.6°C, the lowest temperature was 29.3°C, the maximum motor stator insulation resistance was 11.4GΩ, and the minimum motor stator insulation resistance was 4.12GΩ. The motor stator insulation resistance value decreased with the increase of humidity (for specific changes in motor stator insulation resistance values, see Figure 1 The fourth round of testing changes the trend line).

[0016] In summary, the insulation resistance trends of the four tests are shown in Figure 1 ,from Figure 1 As can be seen, the motor stator insulation resistance values ​​in the first three tests mostly showed no upward trend as the temperature dropped. This is primarily because dirt on the motor surface, when exposed to moisture, causes the stator insulation resistance to decrease. The combined effects of temperature and humidity can cause irregular changes in the motor stator insulation resistance, necessitating regular motor dust removal.

[0017] Example 2: Figure 2 As shown in the figure, the insulation status assessment of a city's subway motor based on the traction motor insulation resistance test:

[0018] 1) After the train returned to the depot and stopped, the first test was conducted. The highest temperature of all motor stator windings in the train was 101.0°C, and the lowest temperature was 77.5°C. The maximum stator insulation resistance value was 16.70GΩ, and the minimum stator insulation resistance value was 8.84GΩ. The higher the temperature of the motor, the lower the stator insulation resistance value. The relationship between the stator winding temperature and the stator insulation resistance value is relatively clear.

[0019] 2) 47 minutes later, a second round of testing was conducted. The maximum stator winding temperature of all motors in the train reached 87.8°C, and the minimum reached 65.7°C, a decrease of approximately 13°C compared to the first test. The maximum stator insulation resistance value was 18.4 GΩ, and the minimum was 10.2 GΩ. The variation pattern was the same as in the first test.

[0020] 3) 47 minutes later, the third round of testing was conducted. The maximum stator winding temperature of all motors in the train reached 77.5°C, and the minimum reached 57.4°C, a decrease of approximately 10°C compared to the second test. The maximum stator insulation resistance value was 20.7 GΩ, and the minimum was 10.9 GΩ. The change pattern was the same as in the first test.

[0021] 4) Ten hours later, the fourth round of testing was conducted before the train left the depot. The highest temperature in the stator windings of all motors in the train was 48.9°C, the lowest temperature was 32.4°C, the maximum stator insulation resistance value was 17.9GΩ, and the minimum stator insulation resistance value was 8.9GΩ.

[0022] In summary, the insulation resistance trends of the four tests are shown in Figure 2 ,from Figure 2 As can be seen, the motor stator insulation resistance increased in the first three tests as the temperature decreased. However, due to the damp environment at night, the insulation surface became damp, and the motor stator insulation resistance decreased significantly in the fourth test. The overall motor stator insulation resistance was above 8GΩ, indicating good insulation performance.

Claims

1. A method for testing and evaluating the stator insulation of a train traction motor, characterized in that: The steps are as follows: 1) After the train returns to the depot and stops, use an insulation resistance tester to test and record the stator insulation resistance value of each motor, and use a DC low resistance tester to test and record the stator winding resistance value of each motor. N =R N (t0+235) / R0-235 calculate and record the stator winding temperature t of the Nth test N , where t0 is the stator winding reference temperature, R0 is the stator winding resistance at the reference temperature, R N To test the stator winding resistance value for the Nth time, the stator winding temperature must be above 100°C; 2) Repeat step 1) multiple times until the stator winding temperature t N The temperature is 50-60℃, and the order of the motors tested each time is the same as the order of the motors tested in the previous test. 3) Judgment standard: If the stator insulation resistance value of a motor shows an increasing trend as the stator winding temperature decreases, then the stator insulation condition of the motor is judged to be good; if the stator insulation resistance value of a motor does not show an increasing trend as the stator winding temperature decreases, then the stator insulation condition of the motor is judged to be abnormal.

2. A train traction motor stator insulation testing and evaluation method according to claim 1, characterized in that: A certain time interval is set between two adjacent tests so that the stator winding temperature difference between the two adjacent tests is 10°C to 20°C.

3. The method for testing and evaluating the stator insulation of a train traction motor according to claim 2, characterized in that: Each time you use an insulation resistance tester to test the motor stator insulation resistance, you must test the motor stator insulation resistance for 60s.

4. A method for testing and evaluating the stator insulation of a train traction motor according to claim 3, characterized in that: If the motor stator insulation is determined to be in good condition in step 3), perform step 1 again and record the ambient temperature and relative humidity before the train leaves the depot. Under normal conditions, the motor stator insulation resistance will tend to decrease due to moisture. Assess the degree of contamination on the motor stator winding surface based on the degree of decrease.

5. The method for testing and evaluating the stator insulation of a train traction motor according to claim 4, characterized in that: Each time you use an insulation resistance tester to test the motor stator insulation resistance, you must test the motor stator insulation resistance for 60s.

6. A method for testing and evaluating the stator insulation of a train traction motor according to claim 5, characterized in that: Each motor performs step 1) three times.

7. A method for testing and evaluating the stator insulation of a train traction motor according to claim 6, characterized in that: A certain time interval is set between two adjacent tests so that the stator winding temperature difference between the two adjacent tests is 10°C.

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