Electric properties of a 66 kV 3-core superconducting power cable system

A 100 m-long, 66 kV, 3-core high temperature superconducting power cable system prototype has been developed and installed in order to verify its properties and performance for practical use. The cable is a cold dielectric type with three cable-cores placed in co-axial stainless corrugated pipes. After cooling the cable to LN₂ temperature, long duration tests, such as that for nominal current-voltage loading and that for load fluctuation, were performed for a one-year period. The cable was warmed to room temperature after each test to investigate the influence of the heat cycle. Critical current was more than 2.7 kA at 77.3 K, and AC loss was 0.7 W/m/phase at 1 kArms. The magnitude of shielding current was almost equal to the transport current. Capacitance, dielectric losses and other electric properties were also measured. All values showed no change during the tests, and were in good agreement with calculated expectations.