Test of two prototype high-temperature superconducting transmission cables

Two 500-A class prototype high-temperature superconducting (HTS) power cables have been constructed by Southwire Company and tested at Oak Ridge National Laboratory (USA). In the first power cable, no insulation was used to separate the individual HTS tapes. In the second cable, Kapton tape was used to insulate the HTS tapes between successive layers for the study of AC loss and current distribution. The power cables were tested with both DC and AC currents in liquid nitrogen from 77 to 69 K. Both cables achieved DC critical current, I/sub c/ greater than 500 A. A calorimetric technique that measures the cable temperature rise under AC currents was used to measure the AC loss of the tables. The noninsulated cable showed a cryoresistive behavior under the 60 Hz AC currents. The insulated cable started to show measurable at loss at current where there was corresponding DC resistive voltage.