How to judge the quality of off-line three-phase asynchronous motor?

How to detect whether the AC three-phase asynchronous motor is good or bad?

1. Use a 500V megohmmeter to measure the insulation resistance of the motor winding and the casing should not be less than 0.5 megohm; use a multimeter to measure the leads of the winding, and there is no disconnection. The above items all meet the requirements, and the performance of the motor is good.

2. Use a pointer multimeter or a digital meter with a capacitance file to check the quality of the capacitor, which can be directly measured.

3. Turn the multimeter to the 1k or 10k resistance level and measure the two leads of the capacitor. It is good for the needle to deflect to the right quickly and then slowly return to the capacitor on the left; always deflecting to the right indicates that the capacitor has been broken down; the pointer does not move Then the capacitor is disconnected or has no capacity.

How to judge whether the offline motor is good or bad?

1. Use a multimeter to measure the DC resistance of the three-phase winding of the motor. The closer the results of the three measurements, the better. When the difference is more than 10%, the phase with the smaller resistance may have an inter-turn short circuit.

2. Use a 500V insulation meter to measure the phase-to-phase insulation resistance of the three-phase winding and the insulation resistance to the ground (to the chassis). The insulation resistance of the motor stored for a long time is above 0.5 megohm, which is a good motor and can be used. More than 0.1 megohm and less than 0.5 megohm indicates that the motor has been damp, and it can be used after drying. A low insulation resistance indicates that the insulation has failed.