Principle of Air Circuit Breaker (ACB)

Air Circuit Breaker (ACB) is a crucial device used in low voltage power distribution systems for protection, control, and isolation. It is designed to interrupt fault currents and safeguard equipment from overloads, short circuits, and ground faults.

🔹 Basic Working Principle

The working principle of an ACB is based on air as the arc extinguishing medium. When a fault occurs, the ACB detects abnormal current flow through its protection system (overcurrent, short-circuit, earth fault). Once the fault is detected:

1. Tripping Mechanism Activated:
   The breaker receives a signal from the trip unit and automatically opens the main contacts.

2. Arc Formation and Interruption:
   When contacts separate, an electric arc is generated. The arc is blown into the arc chute, where it is divided and cooled by arc splitter plates. Air cools and stretches the arc until it is completely extinguished.

3. Circuit Isolation:
   After arc extinction, the current flow stops and the circuit is safely disconnected.