Theoretical and Experimental Analysis of AC Loss Characteristic of Bifilar Pancake Coil With Coated Conductor

According to recent studies, economical feasibility of resistive superconducting fault current limiters (FCLs) in transmission and distribution power line is confirmed. Since the SFCL is operated under alternating current (AC), it causes power loss, so-called AC loss, during normal operation condition even though it is superconductor. Bifilar pancake winding with coated conductor (CC) is expected to reduce AC loss of the SFCL by canceling magnetic fields efficiently as compared with other type SFCLs using CC in the same length. AC loss characteristic of the bifilar pancake type coil for SFCL application was investigated in this paper. Two bifilar pancake coils were wound using CC with facing on high temperature superconductor (HTS) sides each other and substrate (Ni-W) sides each other, respectively. AC losses of the coils were measured at 77 K and theoretical analysis was performed by finite element method (FEM). The experimental results are compared with the Norris equations and numerical values using FEM.