ZW8-12 series outdoor high-voltage vacuum circuit breaker (hereinafter referred to as "circuit breaker") is used in the three-phase power system with AC 50Hz and rated voltage of 12kV, as the use of load distribution and combination current, overload current and short-circuit current. The circuit breaker can be configured with a reclosing controller, which can identify the current characteristics and realize the isolation of multiple automatic reclosers or permanent faults; The self-provided PT is used as the power supply, which becomes an intelligent circuit breaker with voltage and current signal output and control; The power supply is provided by the electronic PT and the three-stage composite protection of overcurrent delay, inrush current delay and short-circuit quick break can be completed.