Working principle and function of vacuum circuit breaker

A vacuum circuit breaker (VCB) is an electrical switching device that is used to control, protect and isolate electrical equipment in power systems. It works on the principle of vacuum interrupter technology, where the contacts of the breaker are sealed in a vacuum environment, preventing the arc formation when the contacts are separated.

The main function of a vacuum circuit breaker is to break the electrical circuit during normal and abnormal conditions. During normal conditions, when the electrical load is within the specified limits, the VCB allows the current to flow through the circuit, and when the load exceeds the specified limit, the VCB opens the circuit to protect the equipment from damage.

The working principle of a vacuum circuit breaker involves the following steps:

1. The contacts of the breaker are closed, allowing the current to flow through the circuit.

2. As the current flows through the contacts, it creates an electromagnetic field that forces the contacts apart.

3. Once the contacts begin to separate, the circuit current is interrupted, and the vacuum interrupter extinguishes the arc that is generated due to the current interruption.

4. The breaker then opens the circuit, isolating the equipment from the power source.

The key components of a vacuum circuit breaker include the vacuum interrupter, operating mechanism, and control electronics. The vacuum interrupter is the heart of the VCB, and it consists of a set of metal contacts enclosed in a vacuum chamber. When the breaker operates, the contacts move towards or away from each other, creating a vacuum arc that is extinguished by the vacuum environment.

Overall, vacuum circuit breakers provide reliable and efficient protection for electrical equipment and systems. They are commonly used in high-voltage power systems, such as power plants, substations, and industrial plants, where the interruption of high current is required.