Current Status of Relay Protection of Mine 35 kV Power Line and Its Improvement Measures

Current status of relay protection of 35 kV power line of a mine was introduced and main problems were pointed out, namely difficult setting of protection value and matching of up-down time limit which usually lead to faults of protection failure and overstep tripping. Some improvement measures of relay protection were put forward including using advanced digital relay protector, adopting pilot protection of power lines, adding low-voltage latch-up protection, and adding fault recorder. An application example of GPRS distributed alarming system with fault recording in relay protection of mine power line showed that using advanced technique and devices could improve reliability of relay protection of mine power lines and stability of power network running.