Investigation of YBCO Coated Conductors for Fault Current Limiter Applications

The switching behavior of second generation (2G) HTS wires with a coated conductor (CC) architecture for application in fault current limiters (FCL) has been studied. Measurements have been performed on short pieces of meter length, as well as on bifilar coils wound from 20 meters of CC. CCs with and without stainless steel stabilizers have been compared regarding the temperature reached after applying a constant voltage per length to the conductor for a certain time (typically 50 ms). Three coils from stainless steel stabilized wires have been connected in series to demonstrate uniform switching of the individual coils in a single phase FCL model with 120 kVA nominal power. The response to transient currents has been investigated by applying currents above the critical current Ic with different amplitudes and measuring the time at which an irreversible voltage increase occurs. All CCs investigated proved well suitable for FCL applications exhibiting the required uniformity and excellent current limiting performance.