Electrical and Thermal Characterization of Commercial Superconducting YBCO Coated Conductors

This paper reports on experimental and modelling activities aimed to identify E(I,T) characteristics of commercial YBCO High Temperature Superconductor Coated Conductors (HTS-CCs). The aforesaid approach is applied to investigate the HTS-CCs behavior in the different regimes: superconducting state, flux-creep, flux-flow and normal state. In order to thoroughly represent the HTS-CCs behavior, parameterized analytical formulations of E(I,T) characteristics have been assumed and then validated through fitting methodologies. Numerical calculation of the electric field as a function of the temperature and of the current density in the HTS-CC, is fundamental to the development of models suitable to design devices based on HTS-CCs. In fact it allows improving the dedicated-software calculation accuracy. This is particularly important for the simulation of Superconducting Fault Current Limiters (SFCL) behavior against short-circuits and/or overloads events, because during the SFCL limitation the HTS-CCs performance strongly depends on the different above mentioned regimes. As matter of fact, numerical simulations are somewhat simpler for high prospective currents as compared to intermediate conditions as for overload or low short-circuit currents.