How to judge the quality of the motor when it does not rotate?

Sometimes, the deceleration motor may not rotate during use. So, let's summarize how to determine the quality of the three-phase asynchronous motor coil and what instruments should be used for inspection:

1. A megohmmeter can be used to measure the insulation resistance between motor phases and phase to ground, and should not be less than 0.5 megohms. If the insulation resistance measured with a 500V megohmmeter is greater than 0.5M, it indicates that it is good. If it is lower than 0.5M, it indicates that the motor is broken. However, this is only an appearance judgment. For inter turn short circuit and phase to phase breakdown, it can only be disassembled and inspected.

2. A multimeter is used to measure the continuity of motor coils.

3. Single arm bridge, precise measurement of coil resistance, can determine whether the resistance of each phase coil is close, especially after rewinding.
The faults of electric motors are nothing more than two aspects: mechanical and electrical.

Mechanical aspects include:
1. Whether the bearings are lacking oil or damaged,
2. Is the end cover running on the outer sleeve and the bearing running on the inner sleeve.
The main electrical aspects include:
1. Whether the insulation resistance is qualified,
2. Whether the three-phase DC resistance is qualified, measure it with a double arm bridge,
3. Whether the rotor is broken or not, the DC resistance of the motor is an important basis for judging the motor.