Air Circuit Breaker
Air Circuit Breaker (ACB) is an electrical device used to provide Overcurrent and short-circuit protection for electric circuits over 800 Amps to 10K Amps. These are usually used in low voltage applications below 450V.
Air circuit breakers operate with their contacts in free air. Their method of arc quenching control is entirely different from that of oil circuit-breakers. They are always used for a low-voltage interruption and now tends to replace high-voltage oil breakers. The below-shown figure illustrates the principle of air breaker circuit operation.
It may increase the arc voltage by lengthening the arc path. As the length of arc path is increased, the resistance of the path is increased, and hence to maintain the same arc current more voltage is required to be applied across the arc path. That means arc voltage is increased.