110 kV three-phase circuit breaker

The design and main operation features of an outdoor 110 kV three-phase circuit breaker, using vacuum interrupters (VIs), are presented. The circuit breaker comprises three poles, each containing two vacuum interrupters in series, a switching mechanism performing the breaking/making operations in the VIs, and a drive. The design of the pole is shown to consist of two vertically positioned units each containing a VI and a switching mechanism provided with a tuning element synchronizing the breaking/making operations of the six VIs. The contact surfaces of the pole VIs, which have passed life test involving short circuit interruptions, were subjected to a thorough examination. The results are presented as well.