1, dry transformer long-term overload operation, windings by high temperature and burned, and even insulation fall off caused by turn or inter-layer short circuit.
2, the line short circuit protection failure, resulting in the transformer long time to bear the impact of large current, the winding by a lot of electromagnetic force and displacement or deformation, at the same time the temperature rises quickly, resulting in insulation damage.
3, dry transformer damp or insulation oil moisture, or repair windings, insulation paint is not soaked, will cause insulation decline, and even cause inter-turn short circuit.
4. Bad contact between winding connector and tap switch.
5, the transformer is struck by lightning, and the lightning protection device is improper or fails, so that the winding is subjected to strong current impact.
Service