ZW20-12/T□-□ series outdoor high-voltage vacuum circuit breaker (hereinafter referred to as circuit breaker) is an outdoor power distribution equipment with a rated voltage of 12kV and three-phase AC 50Hz. It uses vacuum arc extinguishing and SF6 gas as the insulating medium, and is an improved product of ZW20-12F type pole-mounted vacuum circuit breaker. The box adopts VSP5's gas sealing, explosion-proof and insulation structure technology, and the sealing performance of the inlet and outlet line ducts has also been improved. The overall sealing performance is excellent, and the SF6 gas filled inside does not leak and is not affected by the external environment; its spring operating mechanism has been miniaturized and optimized for reliability and stability, and adopts a direct-acting chain main drive and a multi-stage tripping system. The action reliability and stability are several times higher than that of the traditional domestic spring operating mechanism; the contact between the shaft and the sleeve of the main circuit adopts an inward-retracted and outward-stretched watch chain structure, and the contact resistance of the main circuit is small and the temperature rise is low. Therefore, ZW20-12F type outdoor pole-mounted vacuum circuit breaker is a maintenance-free product and a top-quality pole-mounted circuit breaker.