Switching Transients in 400 kV Transmission Network due to Circuit Breaker Failure

The paper presents the case study of SF6 circuit breaker failure during switching-off an unloaded and relative long 400 kV transmission line. Both breaking chambers of the circuit breaker were destroyed. Due to the specific place and type of fault the relay protection system did not operate during circuit breaker failure and transients have been recorded only by a power quality monitoring system installed in the nearby line bay. Recorded events were used for circuit breaker post-mortem analysis. Simulations and fault analysis were carried out using EMTP-RV software.