Out-of-phase switching voltages and their effect on high-voltage circuit breaker performance [includes discussion]

This paper comprises an analytic study of dynamic voltages to be expected at the terminals of a tie-line circuit breaker during the separation of two parts of a system 180 degrees out of phase. Transient voltage crests have been investigated on the analogue computer for a typical system under faulted and unfaulted conditions and the results are compared with oscillographic records obtained on an actual power system. Finally, high power laboratory data obtained on modern high-voltage circuit breakers opening fault currents at twice normal voltage and higher are evaluated in the light of the maximum possible duty indicated by the analytic study.