Quench Properties of 500-m HTS Power Cable

To cope with the increase in electric power demand and provide an alternative technology to conventional electric power transmission cables, it is hoped that high-temperature superconducting (HTS) cables would be developed. A protective layer has been adopted in HTS cables as a countermeasure against short-circuit current. This protective layer is established in parallel, and is connected to the HTS cable at both ends of the cable. However, this protective layer is not effective for quenching the local degradation of HTS wire in the overload-current domain, which slightly exceeds the rated current in real cables with lengths of several km. Therefore, of concern is the possibility in which the generation of bubbles via an exothermic reaction affecting the electrical insulation, when local quenching occurs. In a 500-m HTS power cable, we applied an external magnetic field to a part of the HTS cable, and the superconducting cable was locally quenched. Quench propagation features and electrical insulation characteristics based on this enforced quenching were determined experimentally.