Development of a termination for the 77 kV-class high Tc superconducting power cable

A termination for 77 kV-class high Tc superconducting power cables was designed and fabricated. The termination is insulated with SF/sub 6/ gas, nitrogen gas and liquid nitrogen and is cooled with liquid nitrogen. The current lead has a cross sectional area altered along its axis in order to decrease the heat inlet and to prevent SF/sub 6/ gas from liquefying. The current lead is insulated with ethylene-propylene rubber (EPR) because it passes through nitrogen gas which has low dielectric strength in comparison with liquid nitrogen and SF/sub 6/ gas. 200 A AC current and 70 kV AC voltage to ground were successfully applied simultaneously for 40 hours in total. The measured heat loss of the termination, 19 W, is in good agreement with the calculated value. As the next step, the applied voltage was increased and the termination was confirmed to withstand the voltage up to 120 kV AC and 400 kV Imp to ground.