The chassis is mainly used for components such as circuit breaker and mutual inductor in the extractive switch equipment, and it is promoted and withdrawn as the auxiliary operation of the components and busbar connections.When working with the internal organs of the chassis and the circuit breaker and other interlocking mechanisms of the central cabinet, the "five defense" interlocking requirements of GB3906 can be met. The specific functions are as follows:

1, handcart, only in the test/isolation or job position, circuit breaker closing, and after the circuit breaker closing, handcart cannot move, thereby preventing the misconnection mistakenly combined isolation contact with load. 

2. When the handcart is in the working position or the test/isolation position is about 10mm, the grounding switch can not be closed to prevent the electrically charged false grounding switch. 

3. When the grounding switch is closed, the handcart cannot be moved from the test/isolation position to the working position to prevent the closing of the circuit breaker when the grounding switch closes. 

4. Once the chassis is inside the cabinet, the handcart will not be pulled out of the cabinet once the test/isolation position is removed.