1. The role of vacuum circuit breakers
The vacuum circuit breaker (also called VCB) is named because of its arc extinguishing medium and the contact insulating medium after arc extinguishing are high vacuum. Therefore, vacuum circuit breakers are often used in distribution networks such as frequent operation and long-term arc extinguishing without maintenance. It plays the role of electrical equipment protection and control.

2. Working principle

When the moving and static contacts of the circuit breaker are driven by the operating mechanism to perform the opening act, a certain arc will be generated between the contacts. At the same time, the surface of the vacuum circuit breaker contact volatilizes steam under the action of high temperature. Because the structure and shape of the contact are specially designed, it will cause a magnetic field phenomenon when the current passes. At this time, the arc will move rapidly along the tangential direction of the contact surface under the action of the magnetic field, and a part of the metal vapor will condense on the shield. When the arc naturally crosses zero, it will be extinguished. The medium strength of the head key will be quickly restored.

3. Advantages 

The vacuum circuit breaker is small in size and can be operated frequently, and the arc extinguishing medium does not need to be overhauled. The vacuum circuit breaker with a permanent magnet mechanism has fewer moving mechanisms, no mechanism release and lock devices, less fault sources, high reliability, and lifetime maintenance-free.