Fundamental Study of Ground Fault Accident in HTS Cable

High-temperature superconducting (HTS) power cable has significant merits of compactness and large power transmission capacity. Although the stability of the HTS cable system was verified by in-grid operation, the verification of its safety and reliability against various accidents is required for practical use of this system. A ground fault accident is one of the typical accidents of a conventional cable. If this fault occurs by breakdown of the dielectric layer, the generated arc energy is dissipated into the environment in various forms. As a result, the safety of the public may be jeopardized. Arc energy relates to arc voltage, which is dependent on the inherent physical properties of the faulted equipment. The use of coolant and the structure of the HTS cable differentiate it from a conventional cable, so it should be verified how these differences influence the arc voltage. Accordingly, ground fault tests using the HTS cable were conducted and the arc voltages were compared to that of a conventional cable. The results obtained proved that the arc voltage on the HTS cable is similar to that of a conventional cable, in spite of the differences concerning the use of coolant and the cable structure.