Reduction of Eddy Current Loss in Metal Sheath of 154 kV Transmission Cable

Abstract

The power cables in underground transmission lines consist of a conductor, an insulator, and a metallic sheath. The metallic sheath serves to protect the cable from external physical impacts. When a large fault current is applied to the transmission line owing to an accident, the metallic sheath prevents the fault current from penetrating into the transmission-line current and thus enhances the reliability of the transmission line. However, owing to the alternating current flowing through the conductor, an eddy current is generated in the sheath and a loss occurs. Thus, the overall transmission efficiency is reduced. In this paper, an eddy current loss in a metallic sheath was analyzed using an analytical method, and the results thus obtained were verified by comparing them with those obtained using the finite element method. In addition, a design was proposed for reducing the eddy current loss.