Design of An Induced Voltage Withstand Test Device for Potential Transformer

Potential transformer (PT) is widely used as a sensing device in AC power systems. It is necessary to carry out an induction withstand test on the PT before it is put into operation to ensure its safety. However, due to the influence of stray capacitance, the port current of the PT will rise rapidly during the tests, which will bring risks to equipment and personnel. In engineering, the port current can be limited by connecting an inductor in parallel with the protection winding. However, it is hard to determine the value of the compensation inductance, which restricts the application of this method. This paper proposed an improved PT induction withstand test method. This method obtains the value of the compensation inductance by the pre-test and then conducts the induction withstand with the inductor in parallel with the protection winding. Then, the port current of the PT can be greatly reduced during the test, which guarantees the safety of the test. The corresponding device has been designed to perform the test steps automatically. The experiment results show that the improved method can greatly reduce the port current during the induction withstand tests, which proves the effectiveness of the method.