Insulation Characteristics and Fault Analysis of HTS Cable via Stepped Frequency Waveform Reflectometry

The characteristics of the HTS cable including conductivity, permittivity, and insulation characteristics vary depending on the conditions of temperature and pressure during operations. We propose a diagnostic method that estimates the propagation constant of the HTS cable and detect the location and the degree of the fault using stepped frequency waveform reflectometry. The performance of proposed method is verified by the HTS cable experiment regarding the propagation constant estimation and the fault detection. The results of HTS cable cooled by the liquid nitrogen are also compared with the results at the room temperature to analyze the insulation characteristics change according to the state. The proposed method is expected to be further applied to monitor the condition of HTS cable system regarding temperature and pressure.