There are many reasons for automatic power failure: first, the line is short-circuited for a long time; second, the motor has been damaged and cannot work normally; third, the signal of automatic scrapping. Methods: 1. Monitor the overheating and burning of the power transformer of the movement. The reason is that the user forgot to cut off the power supply after using the range hood, which made the low-power power transformer live for a long time and the primary coil overheated and burned.