The 2nd in-grid operation of superconducting cable in Yokohama project

The superconducting cable system was installed and operated in the real grid of Tokyo Electric Company (TEPCO) Holdings from 2012 to 2013, successfully. At this operation, the system had no degradation of its electrical and mechanical performances. After then, its cooling system was replaced to new turbo-Brayton refrigerator and the cable was re-connected to the grid in 2017. The cable system was successfully operated for another one year. In this operation, stable cooling system controlling, heat loads and vacuum rates of the cryostats etc. were observed continuously. After the operation, No Ic degradation of whole length was measured. In addition, the short sample cables cut from the system after the dismantlement, were applied with AC 90 kV and Imp 385 kV, successfully as the same condition of the shipping test in 2011. These results are one of the credibility confirmations for long time superconducting cable system operation.