Decompression cooling system operation for HTS power cable in the KEPCO power grid

A 3-phase 22.9 kV/50 MVA 410 m HTS power cablesystem was installed at power grid of KEPCO and had been operated for 20 months. In the HTS cable system, an open type cooling system was constructed for cooling LN2 using as coolant for superconducting cable. The cooling capacityof the cooling system was 6 kW at 69 K. SubcooledLN2 flew thorough 410 m HTS cable, maintaining 69 K of operating temperature for HTS cable. The electric loadhad fluctuated continuously with the load status so that the cooling state was also controlled to keep stable operating condition. The consumed LN2 used for making subcooledstate was refilled periodically, and the amount was 3 tons in average. During all the operating period, the HTS cable system supplied electric power stably without any problem.