Vacuum circuit breaker serves in the power system of 10kv and three-phase ac 50hz to function as switching different kinds of loads needing frequent operation, and can protect and control electric equipment in the industrial & mineral enterprise, power plant and substation as well. It can coordinate with the kyn28a-12(gzs1) middle-arranged manual-driven switchgear or xgn- stantionary switchger as well. Main technical parameter: Rated voltage 12kv Rated current 630~3150a Rated short-circuit breaking current 20~40ka Rated peak withstand current 50~100ka Rated short-time withstand current 20~40ka Rated duration short-time 4s Machanical endurance 20000 times Carton package