Abstract: Jinxinda Coal Mine is currently facing severe problems of override tripping and large-scale power outages.In order to solve the problem of override tripping in the high-voltage power supply system,an analysis of the current situation of the power supply system and the principle of anti overload protection is conducted,and the hardware circuit and control program of the protective device are developed based on the high-voltage power grid short-circuit protection principle of optical fiber atresia.By activating and triggering the tripping action of the lower level switchgear,the fault area can be quickly isolated to ensure the stability of the power system.The performance test results show that when the input current is 200 A,the system works normally without any switch tripping phenomenon.When the input current exceeds 200 A,all lower level switches trip within 160 ms time;If for some reason the lower level switchgear fails to trip,the preset protection mechanism of the upper level switchgear will automatically start within a very short period of 162 ms,quickly cutting off the faulty section.The dual insurance measures greatly reduce the risk of tripping accidents caused by faults.The research results can provide reference for improving the reliability and safety of mine power supply systems.