The winding is a component of the motor. Aging, damp, heat, erosion, foreign matter intrusion, and impact from external forces can cause damage to the winding. Motor overload, undervoltage, overvoltage, and phase loss operation can also cause winding failure. Winding faults are generally divided into winding grounding, short circuit, open circuit, and wiring errors. Now separately explain the failure phenomenon, the cause and the inspection method. Winding ground Refers to the grounding caused by the insulation damage between the winding and the iron core or the casing. 1. Failure phenomenon The housing is electrified, the control circuit is out of control, and the winding is short-circuited and heats up, causing the motor to fail to operate normally. 2. Cause Moisture of the windings reduces the insulation resistance; long-term overload operation of the motor; harmful gas corrosion; metal foreign objects invade the windings to damage the insulation; insulation damage when rewinding the stator windings and touch the iron core; the winding ends touch the end cover base; the stator and rotor friction cause insulation burns ; Lead wire insulation damage collides with the shell; overvoltage (such as lightning strike) causes insulation breakdown. 3. Inspection method ⑴ Observation method. Observe whether there is damage and burnt traces by visually inspecting the ends of the winding and the insulation in the wire slot. If there is, it is the grounding point. ⑵ Multimeter inspection method. Use a multimeter to check the low-resistance gear, and the reading is very small, it is grounded. (3) The megohmmeter method. Choose different megohmmeters to measure the insulation resistance of each group of resistors according to different grades. If the reading is zero, it means that the winding is grounded. However, for the motor insulation to be damp or breakdown due to an accident, it needs to be judged based on experience. Generally speaking The pointer swings irregularly at "0", which can be considered to have a certain resistance value. ⑷ Light test method. If the test light is on, it means that the winding is grounded. If sparks or smoke are found somewhere, it is the winding grounding fault point. If the lamp is dimly lit, the insulation has a ground breakdown. If the light is not on, but sparks appear when the test rod is grounded, it means that the winding has not broken down, but is seriously damp. You can also use hardwood to tap on the edge of the stopper of the shell. When you tap a place and wait for it to turn off and turn on, it means that the current is on and off, and that place is the grounding point. ⑸ Electric current burning method. With a voltage regulating transformer, after connecting to the power supply, the grounding point quickly heats up, and the place where the insulation emits smoke is the grounding point. Special attention should be paid to small motors not to exceed twice the rated current for no more than half a minute; for large motors, 20%-50% of the rated current or gradually increase the current, and immediately cut off the power when the grounding point just emits smoke. ⑹ Group elimination method. For the grounding point is inside the iron core and it burns more severely, the burnt copper wire and the iron core are fused together. The method used is to divide the grounded one-phase winding into two halves, and so on, and finally find the grounding point. In addition, there are high-voltage test method, magnetic needle exploration method, power frequency vibration method, etc., which will not be introduced here. 4. Treatment method ⑴ If the winding is grounded due to damp, it should be dried first. When it is cooled to about 60-70℃, it should be dried after being poured with insulating paint. ⑵ When the insulation of the winding end is damaged, re-insulate the ground, paint, and then dry. ⑶ When the winding grounding point is in the slot, the winding should be rewinded or part of the winding components should be replaced. Finally, use different megohmmeters to measure, and meet the technical requirements.