ZW8-12(G)series assembled circuit breaker is kind of 12kv,50Hz three phase current high voltage outdoor switch device consist of ZW8-12 circuit breaker and isolator. They are mainly used for breaking loading current, over load current, fault current in rural or urban power grid and small-scare power system and also used as segment switch. Vacuum interrupter is in the metal case, taking advantage of SMC insulate material to realize phase insulation and ground insulation.