Method for Measuring the Exciting Current of Current Transformers by Using an Auxiliary Winding

Exciting current is the root cause of electric energy measurement error. In this paper, a method for measuring the exciting current of current transformers by using an auxiliary winding is proposed. This method utilizes an auxiliary winding attached to current transformers as a key component for obtaining the operating data of the exciting current. By measuring the open circuit voltage of the auxiliary winding port and the voltages when the port is connected to different resistances, the equations can be established to calculate the exciting current from the measured voltages. This enables the on-line measurement of the exciting current, thereby obtaining the current working state of the core. Additionally, according to the proposed exciting current measurement method, a measurement system for the exciting current using the auxiliary winding is designed. The corresponding measurement implementation plan is provided and some measurements are conducted. The results confirm the feasibility of the proposed auxiliary winding method.