Degradation of YBCO Coated Conductors Due to an Over-Current Pulse

YBCO coated conductors are candidate materials for future electric power devices such as transmission cables, transformers, and fault current limiters. In practical applications, YBCO coated conductors are subject to short-circuit fault currents greater than the operating current. These fault currents cause heat generation, resulting in degradation of the characteristics of YBCO coated conductors. It is therefore necessary to identify the maximum temperatures under which YBCO coated conductors can operate without suffering degradation. To date, we have carried out preliminary experiments on the degradation of YBCO coated conductors due to an over-current pulse. We also focused on the relationship between increases in temperature and Ic degradation. In this study, we prepared YBCO coated conductors fabricated by TFA-MOD method. We also carried out over-current tests to investigate the Ic degradation and performed numerical simulations on thermal stress to estimate the stress and strain acting on the YBCO layer.