1, prevent load closing: After the vacuum circuit breaker trolley in the high voltage distribution cabinet closes in the test position, the trolley circuit breaker cannot enter the working position. 2, prevent grounding wire closing: When the grounding knife in the high voltage distribution cabinet is in position, the trolley circuit breaker can not enter and close. 3, to prevent accidental charging interval: When the vacuum circuit breaker in the high voltage distribution cabinet is closed, the back door of the cabinet is closed by the machine on the ground knife and the cabinet door. 4, prevent live grounding wire: The vacuum circuit breaker in the hV power distribution cabinet closes when working, and the grounding cutter cannot be put into operation. 5, prevent with load broaching brake: The vacuum circuit breaker in the high voltage distribution cabinet cannot exit the working position of the trolley circuit breaker when it is running on and off.