The ZW20-12F high-voltage outdoor AC vacuum circuit breaker is primarily designed for a rated voltage of 12kV and AC frequency of 50Hz in three-phase AC power supply systems.This device can provide its own operating power and is equipped with two-phase or three-phase current transformers to detect the working current online,determining the switch's operating status.It achieves overcurrent protection,timely overcurrent protection,and fast-breaking protection functions.Additionally,it includes an indepent zero-sequence or ABC three-phase composite zero-sequence current transformer to detect three-phase zero-sequence components,enabling low-current grounding(i.e.,single-phase grounding)protection.When coordinated with FTU terminal,it facilitates human-machine dialogue through GSM,GPRS,etc.,enabling remote control and setting functions.