Design and Application of a Low-Ratio High-Accuracy Split-Core Core-Balance Current Transformer

This paper describes the design and application of a split-core current transformer (CT) of large dimensions, specifically designed for mounting in a 13.8-kV switchgear cubical on the phase bus bars. Although split-core CTs of high current ratio are available, the authors believe that the core-balance CT described in this paper is unique, as no similar CT was readily available in the U.S./European market. Thus, there is no equivalent installation in the industry of the specifications described in this paper. The CT discussed in this paper was specifically designed to meet the requirements of dimensions and accuracy for sensitive ground fault and directional ground fault relaying.