Current Margin Against the Fault Current in REBCO Coated Conductors

The application of yttrium barium copper oxide (YBCO) coated conductors in power cables is anticipated. In practical applications, high-temperature superconducting (HTS) cables can be subjected to short-circuit fault current and are expected to operate for over 30 years. In order to safeguard the current margin of YBCO coated conductors against fault current, we carried out preliminary experiments on overcurrent characteristics using an HTS model cable. Meanwhile, we performed numerical simulations to clarify the electromagnetic and thermal behaviors of the HTS model cable. In this study, we numerically simulated the fault current waveform in each YBCO coated conductor that constitutes an entire cable. We then carried out experiments focusing on the current-voltage (I-V) characteristics and the current margin without causing critical current (I_c) degradation against the fault current by varying the amplitude of the waveform obtained numerically. Furthermore, we repeatedly applied the fault current to a YBCO coated conductor to experimentally investigate the I_c degradation caused by iterative fault current.