Abstract: When the voltage parallel device fails, it will lead to misoperation or refusal of protection device and loss of electric energy, which is a critical defect. In addition, there are 70 substations with voltage level of 110 kV and above in Chuzhou power grid, with a large number of voltage parallel devices and a high probability of failure. Therefore, a voltage secondary circuit switching device is prepared, which has simple structure and is easy to carry. Using a special power test line, it has the function of judging the voltage difference at both ends, completely avoids the occurrence of voltage short circuit in the secondary circuit, and the defect can be temporarily eliminated by using the device. The device has been applied in the substation, which shortens the repair time and ensures the safe and stable operation of the power grid.