과단면적 계수를 고려한 철심 변류기 설계 방법

An Iron-cored CT Design Considering Overdimensioning Factor

Current transformer (CT) saturation may cause a variety of protective relays to malfunction. The conventional CT is designed that it can carry up to 20 times the rated current. However, the possibility of CT saturation still remains, because the fault current may have substantial amounts of ac and/or de components. This paper presents a iron-cored CT design method to prevent CT saturation. The proposed method employs the overdimensioning factor $(K_{ta})$ considering dc components contained as well as symmetrical ac components in the fault current.