Since resistive superconducting fault current limiters (SFCLs) are inserted to a power system directly, it is necessary to recover instantly after the clearance of a fault. Most resistive SFCLs using BSCCO bulk or thick film have a recovery time of tens of seconds. An SFCL using YBCO coated conductor (CC) has a large surface area contacted to liquid nitrogen. Joule heat flux of the SFCL is smaller than that of other types when a fault occurs. Therefore, it is important for the SFCL employing CC to investigate a recovery time. In this paper, the recovery characteristics of SFCL with respect to applied voltage were analysed in a power system. All tests were performed in liquid nitrogen and sub-cooled nitrogen. From this result, the parameters for recovery time were obtained.

A superconducting fault current limiter (SFCL) using high temperature superconducting (HTS) wire has been developed in Korea. While the first-generation wire has difficulty in adopting various matrices because it is made by PIT process, the second-generation wire has flexibility in the design of its stabilizer. In general, coated conductor (CC) tape is clad with a thick metal layer as a stabilizer on the superconducting layer such as YBCO. In addition, the metal layer has good electrical conductivity. However, resistive SFCL, when a fault occurs, limits fault current using high resistance of the stabilizer. Therefore, the design of stabilizer is one of the most important parts in the design of SFCL. In this paper, over-current characteristics of CC tapes clad with stabilizers having various specifications were experimentally investigated. It was possible to design the stabilizer of CC based on calculation. An SFCL rated on 13.2 kV/630 A was designed using the optimal design of the stabilizer.

Here we suggest stable maximum temperature criteria of YBCO coated conductors (CCs) considering degradation of YBCO by repetitive exposure to excessive temperature rise. Stable maximum permissible temperature was experimentally determined as the maximum temperature at which CC does not suffer from critical current degradation or burnout. By comparing various over-current characteristics with short-circuit characteristics in regards to the pattern of generated resistance and joule heating flux, maximum permissible temperature rise of YBCO CC in superconducting fault current limiter (SFCL) can be determined as 400 K. Our research is expected to provide rudimental basis for the temperature design of various superconducting power applications including SFCL.