Protection Against Ground Faults for a 275-kV HTS Cable: An Experiment

An experiment to simulate a ground fault was conducted by short samples of a 275-kV high-temperature superconductor cable with an artificial ground fault point. Previous examinations confirmed that the sample without protection had been severely damaged, and the cryostat pipes of the sample had been vented by the alternating current of 10 kA. In this experiment, the samples with protection consisting of insulation sheets were tested. The result was that the outer cryostat pipe had successfully kept its soundness despite the severely damaged cable core without regard to protection. The fact that no current flowed in the outer cryostat pipe indicated that the protective layer on the inner cryostat pipe had effectively interrupted the arc discharge.