An Air Circuit Breaker is an electrical protection device used for short circuit and over current protection. It operates in air (where air-blast as an arc quenching medium) at atmospheric pressure to protect the connected electric circuits. The ACB operates at atmospheric pressure in air. ACB is used in the switching mechanism and protection of the electrical system. A circuit breaker is a device, which can A circuit breaker is used for switching mechanism and protection of the system. In this Air circuit breaker the arc is initiated and extinguish in substantially static air in which the arc moves.