Abstract:Transmission line reclosing plays an important role in improving the safety and stability of the power grid. Incorrect operation of reclosing will cause line outages and load loss. This paper studies the failure of reclosing action after the tripping of two 35kV lines in 220kV substation, and analyzes the reasons for line tripping and reclosing failure. In view of the situation that the reclosing action of the protection device fails and the trip position lamp lights up at the same time after the tripping of protection device, after excluding the cause of the secondary circuit failure, a perspective is provided to find the problem from the device operation panel. The closing position relay on the board does not return after the action is the direct cause of this failure. Finally, corresponding rectification measures are proposed for such defects, which effectively improve the reliability of the secondary equipment operation.