Abstract: According to the long power switching time in the substation of high gassy Yuecheng Mine which would directly be affected to the mine ventilation, produ ction safety and others, a RCS-9655S mode fast power switching device was applied.With the working logic of the fast switching device set up, the auto detection anom aly interlock, the protection interlock, PT disconnection interlock, the switch position anomaly interlock and other interlock function of the rapid swtching device was desi gned and the site simulation test was conducted.The results showed that the RCS-9655S power rapid switching device could rapidly cut off the breakdown point and rec over the power supply.Thus different accidents possible occurred due to the overlong switching time by the double circuit power supply in the high gassy mine could be eliminated and the safety hidden dangers could be eliminated.