ZN114-31.5 Indoor High Voltage AC Vacuum Circuit Breaker (hereinafter referred circuit breaker) is the instrument with single phase 50 Hz single-pole indoor model, and the rated voltage is 27.5kV. It is used as the control breaker and failure protection special breaker for energy receipt and distribution of power supply system of railway power traction in the field of power supply and distribution system of substation, switch station and sub-switch post of electrified railway traction, especially for important load and frequent operating condition. This type of product could not only be installed in grid interval with bottom frame, but also in XYN21_31.5 type switchgear.