A vacuum circuit breaker (VCB) is a medium-voltage and high-voltage circuit breaker where the arc quenching happens in a vacuum medium. The process of switching on and closing current-carrying contacts and interrelated arc interruption occurs in a vacuum chamber, called a vacuum interrupter. Indoor vacuum circuit breaker is an important type of vacuum circuit breaker. Indoor VCB is designed for indoor installation and utilizes vacuum interruption technology to extinguish the electric arc generated during circuit interruption.
In the high voltage vacuum circuit breaker working principle, once the VCB contacts are opened within the vacuum, the arc can be generated among the contacts through the metal vapor ionization in the contacts. However, the arc can be quenched easily as the electrons, ions, and metallic vapors generated throughout the arc quickly condense over the outsides of the circuit breaker contacts so that the dielectric strength can be quickly recovered.