Discharge and Current Limiting Characteristics of a Superconducting Fuse

We investigated the basic properties of a superconducting fuse (SF) based on YBCO/Au films. The SF consists of YBCO stripes covered with Au layers for current shunt. The fault current was limited to a designed value within 0.4 msec by resistance generated in YBCO/Au after its quenching. This enabled the SF to transfer small fault power and the suppressed current was sustained for more than 0.5 msec while Au layer melting and arcing. The arcing time was less than 2.5 msec, which is short enough to do self-interruption. Under the source voltage of 100 V/sub rms/, the longer the current limiting time was, the shorter its discharge time was. The current limiting time and its discharge time were reduced as the applied voltages increased in the range of 200-300 V/sub rms/. We thought that this was because the quench propagation was limited by local melting generated from higher voltage. The superconducting fuse could be designed in small size and compact structure using the characteristic of its high current density compared with the conventional fuse. The superconducting fuse was not harmful to the environment because it was immersed in liquid nitrogen.