Abstract: The rcs925a type overvoltage protection and fault starting device produced by Nari Weibo is mainly used for 500K lines,which is the produced WHEN THE 500k system is over-voltage.At the same time,when the relevant protection on the opposite side of the line jumps far,it is used to execute the remote jump command in cooperation with the line’s transceiver.When the 500 line fails,when the voltage reaches the conditions,it will cause the DSP voltage and the alarm has no warning lamp on the device,which is difficult to find,resulting in defective operation,endangering the safe operation of the power system.