Effects of Magnetic Fields on Quench Characteristics of Superconducting Tape for Superconducting Fault Current Limiter.

In DC systems, DC resistive type superconducting fault current limiters (R-SFCLs) can respond within a few hundred milliseconds and limit the fault current to a very low level to protect the power equipment in DC systems. The main part of R-SFCLs are superconducting tapes. When short-circuit faults occur in the system, the superconducting tapes will quench and become a large quenched resistor to limit the fault current. The surrounding magnetic fields and the magnetic fields caused by the superconducting tapes itself influence the quench characteristics of the superconducting tapes of R-SFCLs. Thus, the current limiting characteristics of R-SFCLs will also be affected. Until present, very few studies have investigated the effects of magnetic fields on quench characteristics of superconducting tapes for DC R-SFCL. The objective of this paper is to obtain the effects of magnetic fields on quench characteristics of superconducting tapes for DC R-SFCL. Two different kinds of YBa2Cu3O7-δ (YBCO) tapes are studied under a permanent magnetic field of 0, 42.4, 75.9, 122.9 mT, respectively. One is from Shanghai Superconductor Technology Co., Ltd., Shanghai, China, type ST-12-L (named SC_SH) and the other is from American Superconductor Inc. Boston, MA, USA, type 8602 (named SC_8602). The research results show that the magnetic fields influence both the amplitude and the rising rate of the quenched resistance of an SC_SH tape. Under the same magnetic field, both the speed of quenching and the quenching resistance of SC_SH tape are larger than them of SC_8602 when the prospective current exceeds 800 A. Thus SC_SH tape can limit the fault current faster and to a lower level. [ABSTRACT FROM AUTHOR]