APPLICATION OF SUPERCONDUCTING FILMS TO FAULT CURRENT LIMITER

The applicability of high-T(c)-superconducting films to a fault curren t limiter (FCL) without liquid nitrogen (L-N2) was investigated. The F CL element consists of a 200-nm-thick YBa2Cu3O7-x (YBCO) film having a current-limiting area 4 mm wide and 90 mm long. It is cooled by a ref rigerator. When a voltage of 100 V(rms) (150 A) was applied at 77 K, t he YBCO film transitioned to a resistive state at 13 A and the current was limited to 7 A in less than 0.5 ms. At lower temperature, 74 K, t he transition current increased to more than 30 A, while the limited c urrent remained less than 9 A. Thus, it was considered that a superior FCL system without L-N2 could be obtained.