Ratio Error Reduction of a Current Transformer Using Multiple Winding Technique

Abstract

A current transformer (CT) converts the current of the primary side to the proper current level for the secondary side. Hence, the most important performance of the CT is the reliability of the current ratio. However, it is difficult to maintain a reliable current ratio when a CT is used for large current measurements in, for instance, an electric furnace or when it serves under abnormal conditions such as in high temperature applications or in limited spaces where a proper installation position cannot be guaranteed. Therefore, in the design of a CT, the realization of high reliability and robustness minimizing the transformation ratio error for diverse operating circumstances is crucial. To address these issues, a highly reliable and robust CT using a multiple winding technique is proposed. It is termed the multiple winding CT (MCT) in this paper. With the proposed analysis method, the MCT is designed for the minimization of the ratio error in this research. Moreover, the MCT is designed taking into account the temperature characteristics using a temperature analysis method. The usefulness of the proposed MCT is validated via an experiment.