Answer: There are usually two kinds of winding short circuit faults: interphase short circuit and turn-to-turn short circuit. Turn-to-turn short circuit includes short circuit between coils in each pole-phase group, short circuit between coils in one pole-phase group and short circuit between turns in one coil. Phase-to-phase short circuit fault usually includes interlayer short circuit at the end of winding and short circuit between upper and lower coils in slot. The reason of interphase short circuit is that interphase insulation size does not meet the requirements, the insulation pad itself is defective, and the interlayer pad is offset or damaged when buried. In addition, insulation damage of winding connecting wire or outlet bushing will also cause interphase short circuit. Motor overload, overvoltage, single-phase operation and poor insulation material of wires will all cause short circuit between windings. In particular, the thermal mechanical strength of polyester enameled wire paint film is poor. When the paint dipping is poor and the turns fail to form a solid whole, a large amount of external dust will accumulate in the gaps between the turns, and the wires will vibrate and rub against each other under the action of electromagnetic force, and the dust stuffed in the gaps will play the role of "abrasive". After a long time, the insulation of the conductor will wear out, forming a turn-to-turn short circuit. . Repair of short circuit fault of pole-phase assembly at coil end (1). During welding, the triangular insulating pads between the pole groups at the end of the coil will flow with the solder, form tin flow or burr after cooling, pierce the insulating pads, or burn the insulating pads by the solder, resulting in the breakdown of local insulating pads between phases due to insulation loss, resulting in short circuit between the pole groups. The repair method is to heat the coil to soften the insulation, then pry the coil between the coil groups with a wiring board, reinsert a new insulation pad, and finally paint. (2) Repair of winding short circuit fault caused by insulation damage of connecting wire or bridge wire at winding end. Because the insulating sleeve of the connecting wire is crushed, or the plastic sleeve becomes soft after drying and cannot be insulated, it will cause short circuit between the electrode groups. During maintenance, pry open the connecting wire with the wiring board, clean up the old bushing, and then put in a new insulating bushing or wrap it with insulating tape. On the bridge line between coils, due to improper embedding or molding, coil short circuit fault will also occur. The solution is to heat and soften the coil, pry open the bridge wire with the wire management board and add insulation. (3) Repair of interturn short circuit at winding end. Inter-turn short circuit at winding end is caused by poor paint dipping, inter-turn vibration, wear and insulation. After finding the short-circuit coil by voltage drop method, in order to quickly find out the short-circuit point of the turn, it is suggested to connect the phase coil to single-phase low voltage and connect it to both ends of the short-circuit coil with AC voltmeter. At this time, gently pry open each turn of the short-circuit coil with a wiring board or bamboo board. When the voltmeter pointer suddenly rises to the normal value, it means that the short-circuit point has been separated, and an insulating pad should be placed here, and then painted for insulation. (4) Repair of interlayer short circuit of double-layer coil. The interlayer short circuit between the upper and lower layers of the double-layer coil is caused by the poor interlayer insulation material or the inconsistent size of the interlayer insulation pad and the offset displacement of the interlayer insulation pad when the wire is buried. The fault of short circuit between the upper and lower floors in the box or turn-to-turn short circuit between the coils of the upper and lower floors is handled in the same way as the above-mentioned grounding fault.