Vacuum Circuit Breaker

A Vacuum circuit breaker is a circuit which vacuum is used to extinct the arc. It has dielectric recovery character, excellent interruption and can interrupt the high frequency current which results from arc instability, superimposed on the line frequency current.

In the principle of operation of VCB will have two contacts called electrodes will remain closed under normal operating conditions. Suppose when a fault occurs in any part of the system, then the trip coil of the circuit breaker gets energized and finally contact gets separated.

The moment contacts of the breaker are opened in vacuum, i.e. 10-7 to 10-5 Torr an arc is produced between the contacts by the ionization of metal vapors of contacts. Here the arc quickly gets extinguished, this happens because the electrons, metallic vapors and ions produced during arc, condense quickly on the surface of the CB contacts, resulting in quick recovery of dielectric strength.

Advantages

 <!--[endif]-->VCBs are reliable, compact and long life

 <!--[endif]-->They can interrupt any fault current.

There will be no fire hazards.

No noise is produced

It has higher dielectric strength.

It requires less power for control operation.