The quality of a three-phase motor can be measured using a multimeter. The following is the content of the text of using a multimeter to detect the quality of a three-phase motor:
1. Detection method of three-phase motor.
1.Visual inspection.
First of all, check the appearance of the motor to see whether the end cover, bearing cover and other components of the motor are in good condition, and whether the junction box of the motor is normal. If the surface of the motor is found to be damaged, deformed or corroded, the motor should be replaced in time.
2.Insulation resistance detection.
Using the resistance level of the multimeter, the insulation resistance of the motor can be detected. Put the red and black pen of the multimeter on the two power cords of the motor respectively, and then turn the rotor of the motor to observe the resistance value displayed by the multimeter. Under normal circumstances, the insulation resistance of the motor should be very large, if the resistance value displayed by the multimeter is very small, it means that the motor has a short circuit or leakage fault, which needs to be further checked.
3.DC resistance detection.
Using the resistance file of the multimeter, the DC resistance of the motor can be detected. Put the red and black pen of the multimeter on the two power cords of the motor respectively, and then turn the rotor of the motor to observe the resistance value displayed by the multimeter. Under normal circumstances, the DC resistance of the three-phase winding of the motor should be equal or very small, if the resistance value of the three-phase winding is found to be quite different, it means that the motor is faulty and needs to be further checked.
4.Withstand voltage test.
For newly installed or overhauled motors, a withstand voltage test is required to verify the insulation performance of the motor. Use the voltage level of the multimeter, put the red and black pen of the multimeter on the two power lines of the motor respectively, and then gradually increase the voltage to observe the reaction of the motor. Under normal circumstances, the motor should not have abnormal noise or smoke, etc., if the motor is found to be abnormal, it means that the motor is faulty and needs further inspection.
The criteria for judging the quality of two-phase and three-phase motors.
1.The operating state is stable.
A good three-phase motor should be stable during operation, and there will be no trembling, abnormal noise, etc. If the motor is running unstable, it may be that there is a fault inside the motor and further inspection is required.
2.The magnitude of the current is normal.
A good three-phase motor should have a normal current when it is running, and there will be no excessive or too small current. If the current is not normal when the motor is running, it may be that there is a fault inside the motor or the load is too large, and further inspection is required.
3.The temperature rise is normal.
A good three-phase motor should have a normal temperature rise during operation, and there will be no excessive temperature. If the temperature of the motor is too high when it is running, it may be that there is a fault inside the motor or that the load is too large and needs to be further checked.
4.Low mechanical noise.
A good three-phase motor should have low mechanical noise when it is running, and there will be no obvious mechanical noise. If the motor is running with high mechanical noise, it may be that there is a fault inside the motor or that the load is too large and further inspection is required.
In short, it is feasible to use a multimeter to detect the quality of a three-phase motor, but it needs to be operated in accordance with the prescribed method, and the various parameters need to be accurately measured and judged. Attention should be paid to safety during testing to avoid accidents. If a fault is found in the motor, it should be dealt with in time to ensure the normal operation and service life of the motor.