Measuring the quality of three-phase motor with multimeter How to judge the quality of three-phase motor
The criterion is that the motor winding is on or has an appropriate resistance, and there is no problem with insulation, which means that the motor is good.
If there is no resistance between the three windings of the three-phase motor, it is basically determined that there is no phase-to-phase short circuit in the three-phase winding, and then each phase of the three-phase winding is measured to the ground separately. If there is no resistance, it is determined that the motor is not grounded, and then the resistance of the three windings is measured, regardless of the size of the motor.
When the measured resistance errors of the three windings are very small, it can be determined that the motor is trouble-free. If one or two phases are open or the resistance errors are large, it can be determined that the motor is burnt. If there is any doubt, the end cover can be removed for further confirmation.
Extended data:
Fault treatment of three-phase asynchronous motor;
If the winding is grounded due to moisture, it should be dried first. When it is cooled to about 60-70℃, it should be dried after being poured with insulating paint. When the insulation at the winding end is damaged, it should be insulated again, painted and dried again. When the winding grounding point is in the slot, the winding should be rewound or some winding elements should be replaced.
The short circuit point is at the end. The short-circuit points can be separated by insulating materials, or the insulated wire can be repackaged, painted and dried again, and short-circuited in the wire slot. After softening it, find out the short circuit point to repair it, put it back in the trough, and then paint it and dry it.
When the open circuit is at the end, it should be welded firmly after connection, covered with insulating material, covered with insulating tube, and then dried. If the winding is seriously burnt due to inter-turn, inter-phase short circuit and grounding, a new winding should be replaced.
Emergency treatment shall be made for a few breakpoints where the break point is in the slot, and the breakpoints shall be found by grouping elimination method, which shall be used after the winding breaks are connected and the insulation is qualified. The broken cage of the cage rotor can be repaired by welding, cold connection or bar replacement.
