Evenson Calixte

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

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.

Theoretical evaluation of limiting resistance required for successful interruption in circuit breaker with fault current limiter

The present article describes a method to determine the limiting impedance required to obtain a successful interruption when a circuit breaker is connected in series with a resistive fault current limiter (FCL). This study is carried out for two types of faults: an FCL terminal fault and a short-line fault. The limiting impedance required for satisfactory interruption is estimated as a function of the critical mv of the circuit breaker to be associated with the FCL and the circuit parameters. For different operating voltages, the equations found in this paper show that the knowledge of the critical mv for a circuit breaker enables us to predict the magnitude of the limiting impedance needed to have a successful interruption.

Reduction effect of semiconductor type fault current limiter on interrupting duty of a circuit breaker

Calculations were carried out to study the effect of a semiconductor type of fault current limiter (FCL) upon the interrupting duty imposed on a circuit breaker when a fault occurs at a distance of 1 to 8 km downstream from the load side terminals of the FCL. For comparison purpose, we also look at the interrupting condition when the fault happens very close to the terminals of the circuit breaker The semiconductor type of FCL in current-limiting operation was assumed to have a limiting element composed of either an inductance or a resistance. For all fault locations, the insertion of the resistive FCL proved to decrease not only the fault current, but also the rate of rise of the recovery voltage (RRRV). For the inductive FCL, the RRRV depends mainly upon the stray capacitance C/sub p/ of the limiting coil. Under short-line fault (SLF) condition, the introduction of the inductive FCL with C/sub p/=100 nF is shown to reduce the severity of the SLF transient by reducing the fault current and the RRRV. However for all fault locations, the insertion of the inductive FCL with C/sub p/=10 nF was found to decrease the fault current, while increasing the RRRV.