Evaluation of position of a fault current limiter with regard to the circuit breaker

Calculations were performed to examine the optimum location of a fault current limiter (FCL) with regard to the circuit breaker. The series-connected FCL was assumed to be associated with the circuit breaker in two positions: upstream and downstream from the circuit breaker. In both cases, the characteristics of the transient recovery voltage (TRV) appearing across the circuit breaker with FCL were studied under several fault locations. For both locations of FCL, the presence of the FCL reduces the severity of the circuit breaker duty. Whereas the difference in location of the FCL leads to no variation in the TRV characteristics and the fault current, locating the FCL downstream proved to lessen the voltage at the source-side terminal of the FCL, compared with the FCL located upstream from the circuit breaker. In other words, a gain in the device safety can be obtained by locating the FCL downstream from the circuit breaker.