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

A termination for 77kV-class high Tc superconducting power cables was designed and fabricated. The termination is insulated with SF6 gas, nitrogen gas and liquid nitrogen and is cooled withi liquid nitrogen. The current lead has a cross sectional area altered along its axis in order to decrease the heat inlet and to prevent SF6 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 SF6 gas. 200A AC current and 70kV AC voltage to ground were successfully applied simultaneously for 40 hours in total. The measured heat loss of the termhation, 19W, 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 12OkV AC and 4OOkV Imp to ground.