Method to judge whether the motor is burned out:

1. The motor is short-circuited to the ground. The test method is to connect one end of the shaker to the ground and one end to the motor terminal, and the insulation is zero after the shake test.

2. Use the resistance gear to measure the phase-to-phase resistance of the three-phase motor. If the resistance is infinite, it means that the motor winding is burned out.

The motor windings burnt due to lack of phase operation have obvious damage characteristics. Remove the motor end cover and see that 1/3 (corner connection) or 2/3 (star connection) of the polar phase group at the end of the motor winding is burnt black Or it turns to dark brown, and the remaining one-phase or two-phase windings are intact or slightly burnt, indicating that it is caused by the lack of phase operation. The multimeter can only accurately judge the quality of the winding, and the insulation has to be measured by shaking the meter.

Use a multimeter to measure the DC resistance of the windings of ruv, rvw, and rwu. Normally, the three parameters are equal and have certain readings, which are generally very small. If one of the phases or multiple phases is infinite or there is a big difference, it can be judged that the winding is burnt and opened.

Use a multimeter to measure the resistance of the winding to the ground, and it is qualified as 1 megohm per kv (the minimum insulation resistance of 380v is 0.4 megohm). However, it is not very accurate to use a multimeter (generally the measured value is larger than the actual value), and a shaking table is required if conditions permit.

The First, measure whether the winding is on or off. If you don’t know the resistivity, just set it to the resistance file ×10 or ×100. If it is open, it will not be burned. If it is not through, it will be burned.

The second measurement is whether the ground is grounded. Because the motor is burnt, it is sometimes accompanied by grounding. It is not good if one end is in contact with the wire and the other is in contact with the case. If the pointer does not move, it is intact and the amplitude is large.

The Third, if the motor is three-phase, you can measure whether the resistance of the three-phase winding is balanced.