Current test of a DC superconducting power transmission line

A test of a prototype dc superconducting electric power transmission line (dc SPTL) has been performed at 5 kA and 12 K. A supercritical helium refrigeration system was used to cool the test system which included a cable with a hollow central core so that the go and return refrigerant streams could countercurrently cool the inner and outer surfaces of the cable. Multifilamentary Nb3Sn superconducting wire was developed for the dc SPTL application and extensively tested to establish the optimum fabrication techniques and the expected response of the wire to cabling, operating, and installation stresses.