Reduction in Severity of Circuit Breaker Duty under Generator-fed Fault Condition by Means of Resistive Fault Current Limiter

E. Calixte, Y. Yokomizu, T. Matsumura, and H. Fujita (Japan)



As power systems grow and new generators, lines and transformers are added, short-circuit current values increase. To avert power outage, a fault current limiter (FCL) can be installed in series with a circuit breaker to reduce the magnitude of the fault current. We propose that the installation of the FCL should be done on the basis of a coordination between the FCL and the circuit breaker. This report focuses on an FCL located at the line side of a generator circuit breaker. In the absence of FCL, for fault occurring at breaker terminals, it is possible that the fault current does not go through zero during several periods. Under this fault condition, the present report examines the breaking duty imposed on a generator circuit breaker connected with resistive FCL. The results of this study show that a resistive FCL connected in series with the CB can be used to avoid the occurrence of delayed current zeros. Also, the presence of the resistive FCL makes it possible to use a generator circuit breaker having a lower interrupting capability. The results found via calculations were verified by presenting a theoretical expression of the rrrv as a function of the limited current and the circuit parameters that can be used in transmission and distribution systems.

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