The high voltage power system, main effect of isolating switch is: when the breaker disconnects the circuit, the isolating switch off the electricity, and no local can get clear separation, as assistant to switch roles. Due to external indicator circuit breaker contact position is the lack of intuitive, and in some cases can not guarantee its indication and contact locations to one, thus isolating switch for the electric and non-electric part distinct from every. In addition, isolating switch has a natural arc, commonly used in the voltage transformer and a lightning arrester current is very small set of inputs and disconnected, and a circuit breaker is connected with several settings, the circuit breaker through isolating switch switching is more agile and convenient.