Advantages of VCB, The vacuum circuit breaker has a long life. Safety of VCB/Vacuum Circuit Breaker. This page introduces Vacuum Circuit Breaker or VCB. VCB means vacuum circuit breaker it used in high voltage (HV) lines It has one mechanism in this mechanism spring is there it is connected with small electric. Air circuit breaker is designed to overcome the defects and safeguard the machine before it breakdowns and acts as a safety device of ships.