Application of a first peak non-limiting type FCL

First peak non-limiting type FCL can be utilized for various purposes especially when fault occurs on the load at the outgoing feeder. One of them is to use for preventing spread of voltage sag until the circuit breaker operation. Another is to use for minimizing the blackout area through the protection coordination between main circuit breaker at feeder and the multi-circuit breaker in series at the same line in the underground distribution line. In these two cases, the fault current in itself is not the only factor to consider if the fault current does not exceed the ratings of circuit breakers. The real problem is specific situations caused by fault current as noted above. In order to solve these problems, LSIS has developed first peak non-limiting type FCL depending on customer requirements and installed in POSCO and KEPCO power girds. First peak non-limiting type is more simple, easy to use, and economical than first peak limiting type. This article also reports recent activity by LSIS on development of a 23 kV superconducting fault current limiter and its application in the KEPCO grid.