1. Use a 500V megohmmeter to measure the insulation resistance between the motor winding and the casing, which should not be less than 0.5 megohms; Measure each lead of the winding with a multimeter, and there are no broken wires; When all of these meet the requirements, the motor is good 2. Use a pointer multimeter to check the quality of capacitors (there are also digital meters with capacitance ranges that can be directly measured). Set the multimeter to the 1K or 10K resistance range, measure the 2 leads of the capacitor, quickly deflect the needle to the right, and then slowly return to the left, indicating that the capacitor is good; Always leaning to the right indicates that the capacitor has been broken down; If the pointer does not move, the internal wire of the capacitor is broken or there is no capacity. Note that using this method can only determine the quality of the capacitor

1. Use a 500V megger to shake the insulation resistance of the wires on the three terminals to the motor casing, which should be above 0.5M Ω, indicating that there is no short circuit to ground.

2. Multimeter measurement: Measure whether the resistance values between the A/B/C phases are equal, and it should be similar. Even if there is too much difference, it can be turned, but it will not last long. The larger the motor, the smaller the resistance. But it cannot be 0 ohms for all three phases, unless it is particularly large, such as a motor with a power output of 50KW or above. If it is a variable speed motor, the resistance values of the 6 terminals can be different 3. Check the bearings and fans. Generally, if they are wrapped around the motor, they must be replaced completely. Sometimes, if the bearings lock up, the motor may burn