The 27.5kV permanent magnetic circuit breaker is used to close and open the rated current and fault short circuit current of the traction power supply system, and is an outdoor type device that can be installed in traction substations, subdivision stations, opening and closing stations, AT stations, switching stations and along railway lines. The 27.5kV permanent magnetic circuit breaker adopts air-insulated, vacuum-extinguished operation mode, and the operating mechanism is a monostable permanent magnetic mechanism with reliable operation, excellent characteristics, efficient transmission and streamlined components.