抄録
We have designed and tested a conduction-cooled high-Tc current lead for an AC 1kA or 1kArms (root mean square) fault current limiter, using tubular (Bi, Pb)2Sr2Ca2Cu3O10+x superconductors. A tubular lead has the advantages not only of a high critical current density but also of low AC loss. Preliminary, self-field AC loss was measured at 77K. It was 0.22W for a transporting current of 1kArms for the lead with the dimensions of 34mm in outer diameter, 30mm in inner diameter and 190mm in length. The loss was in good agreement with the numerical calculation by the critical state model, and was much smaller than that calculated for a cylindrical superconductor. In the actual lead system where the lead had a temperature distribution from 77K to 4.2K, the AC loss was less than 0.1W per pair of leads. The lead successfully transported 1kArms for more than 2 hours without any thermal runaway or instability. The total 4.2K heat load of the pair of leads, 1.8W, also satisfied the refrigeration restriction for the fault current limiter.
