Interrupting condition imposed on a circuit breaker connected with fault current limiter

Abstract

The present paper examines the influence of an inductive fault current limiter (FCL) on the interrupting condition, namely the limited current and the transient recovery voltage, to which a circuit breaker is subjected when a fault occurs at a distance of 0 to 8 km distant from the load side terminals of the FCL. In the model of the FCL, a stray capacitance C/sub p/ appearing across the winding of the limiting coil was taken into account. For all fault locations, the rrrv in the presence of the FCL depends mainly upon the stray capacitance C/sub p/. Under short-line fault (SLF) condition, the introduction of the FCL with C/sub p/ = 100 nF proved to decrease the severity of the breaking condition by reducing the fault current and the rrrv. As a result, a lower-rated circuit breaker can be used. However, for all fault locations, the insertion of the FCL with C/sub p/ = 10 nF was found to lessen the fault current, while rising the rrrv. On the other hand, from the variation of the interrupting condition imposed on the circuit breaker due to the insertion of the FCL, the limiting impedance required to allow a circuit breaker to perform a satisfactory interruption is discussed.