Inspection of Five-prevention function of Vacuum Circuit Breaker: 1. When the circuit breaker is in the switch-on position, the handcart of the circuit breaker can’t be pulled out; 2. When the circuit breaker is in the testing position and switch-on state, the handcart of the locking circuit breaker should be pushed to the working position; 3. The circuit breaker can’t be switched on over the moving of the handcart of the circuit breaker; 4. As for the tripping prevention of the circuit breaker, it can be switched on for only once under one order; 5. The grounding switch can’t be turned on when the handcart of the circuit breaker is in the working position; 6. The handcart of the locking circuit breaker should be pushed to the working position when the grounding switch is on the switch-on state