Improvement of Working Voltage of Resistive Fault Current Limiter Using YBCO Thin Films

We developed a current limiting element consists of the YBCO thin film on the sapphire substrate and the Ni film on the AIN substrate to improve a working voltage. The YBCO thin film was connected electrically to the Ni film in parallel. When the YBCO thin film changed to the normal state due to the excess current, the current diverted from the YBCO thin film to the Ni film, and the heat shock to the YBCO thin film was reduced. The working voltage per unit length was 43.3V/cm, which was three times as high as that of the element without the Ni film on AIN. And we constructed a module with six elements connected in series. When the excess current flowed in the module, all elements changed to the normal state and working voltage was at least 1.87kV.