A RESISTIVE FAULT CURRENT LIMITER BASED ON HIGH-TEMPERATURE SUPERCONDUCTORS

A resistive fault current limiter is described that demonstrates the v iability of using high-temperature superconducting (HTSC) elements in this type of current limiter design. The primary design issue surround ing such a fault current limiter lies in insuring that the fault energ y, manifesting itself as Joule heating in the HTSC elements, is safely dissipated without permanently damaging the HTSC elements. This issue can be resolved by utilizing relatively low I-c polycrystalline yttri um barium copper oxide (YBCO) filaments and by placing these filaments in intimate contact with a substantial thermal mass. This thermal mas s is provided by a ceramic-filled epoxy composite that, in addition to its thermal properties, contributes substantial mechanical strength t o the conductor element. Current limiters based on this design have th e advantages of not requiring external fault sensing, an extremely rap id response to fault, and automatic resetting once the fault has clear ed.