VK172-12 Indoor high voltage vacuum circuit breaker (hereinafter referred to as circuit breaker) is an indoor switchgear component with rated voltage of 12kV and below and AC of 50 Hz. The circuit breaker is used together with KYN28A-12 switch cabinet, and can also be installed in XGN2 and other fixed switchgear. The products meet the requirements of GB 1984 high voltage AC circuit breaker, GB / T 11022 common technical requirements for high voltage switchgear and control equipment standards, JB / T 3855 high voltage AC vacuum circuit breaker, DL / T 403 technical conditions for ordering 12kV ~ 40.5kV high voltage vacuum circuit breakers. It has the advantages of small volume, strong breaking capacity, high insulation strength, no pollution, no explosion danger and so on.