| Title |
A Design Method of Iron-cored CTs To Prevent Satruation |
| Authors |
이주훈(Lee, Ju-Hun) ; 강상희(Gang, Sang-Hui) ; 강용철(Gang, Yong-Cheol) ; 이승재(Lee, Seung-Jae) ; 배주천(Bae, Ju-Cheon) ; 안준기(An, Jun-Gi) ; 이청학(Lee, Cheong-Hak) ; 이정택(Lee, Jeong-Taek) |
| Keywords |
Iron cored CT ; Saturation ; Core cross section ; Symmetrical short - circuit current factor ; Transient dimen - sioning factor |
| Abstract |
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 without exceeding 10% ratio error. However, the possibility of CT saturation still remains if the fault current contains substantial amounts of ac and/or dc components. This paper presents a design method of iron-cored CTs for use with protective relays to prevent CT saturation. The proposed design method determines the core cross section of the CT; it employs the transient dimensioning factor to consider relay's operating time (duty cycle) and dc component as well as ac components contained in the fault current, and symmetrical short-circuit current factor to consider as well as ac components contained in the fault current, and symmetrical short-circuit current factor to consider the biggest fault current. The method designs the cross section of CTs in cases of reclosure and no reclosure. |