Abstract
Sheath circulating current is increased in the change of sheath mutual impedance which is caused by unbalanced cable system, and different section length between joint boxes. If excessive current flows in sheath, sheath loss which is reduced the transmission capacity is produced. Recently, excessive sheath circulating current was partially measured in underground cable systems of KEPCO. Accordingly, actual schemes to reduce excessive sheath circulating current are urgently required for installed cable system as well as newly-installing cable systems. This paper describes the relation analysis of sheath circulating current and burying types. And also, various schemes to reduce excessive circulating current using EMTP/ATPDraw and applicable schemes are proposed through a detailed analysis regarding cable systems by considering various electrical and environmental factors. It is evaluated that the proposed reduction schemes can be effectively applied to reduce the excessive sheath circulating current with the minimized electrical problems. And reduction effect is Proved with sheath circulating current reduction equipment.
