Abstract: In Shangshe Coal Mine, the double power fast-switching devices were allocated at coal mine substation inlet line, low-voltage line side of main transformer and line side of main fan room in coal mine power supply system. For the different operation modes of coal mine power supply system and main transformer, and different load types of mine, it made rational fast switching scheme, starting conditions and locking conditions, which effectively avoided the occurrence of large area blackout accidents caused by sudden fault in coal mine power supply system.