1 kArms Bi-2223 Superconducting Current Lead System for the Current Limiter

A 1 kA rms current lead system for the superconducting current fault limiter has been designed and tested. The lead system is composed of powder sintering (Bi,Pb)2Sr2Ca2Cu3O10+x tube lead (80-4 K), Cu lead (300-80 K), a liquid helium vessel and refrigerator which cools the junction of the Bi-2223 and Cu lead to 80 K. The Bi-2223 parts are placed in a vacuum and cooled by heat conduction. This lead system has successfully transported 1 kA rms for 3 hours under steady-state temperature distribution, with a total 4.2 K heat load, 3.5 W, which was a much smaller value than that obtainable with an all Cu lead. AC loss for the tubular Bi-2223 lead was also confirmed to be small.