Air Circuit Breakers (ACBs): Types, Specifications, and Applications

An Air Circuit Breaker (ACB) is a type of circuit breaker that uses air as the arc extinguishing medium to protect electrical circuits from overloads, short circuits, and faults. ACBs are widely used in low-voltage (LV) and medium-voltage (MV) power distribution systems due to their high breaking capacity, reliability, and ease of maintenance.

1. Types of Air Circuit Breakers

ACBs are classified based on their arc quenching method, design, and application:

A. Based on Arc Extinction Method

1. Plain Break ACB

   • Simplest type, uses natural air to extinguish the arc.

   • Suitable for low-voltage applications (up to 400V).

   • Rarely used today due to inefficiency in high-current interruption.

2. Magnetic Blowout ACB

   • Uses electromagnetic forces to stretch and cool the arc.

   • Higher breaking capacity than plain break ACBs.

   • Common in industrial LV systems (up to 800A).

3. Air Chute ACB

   • Arc is split into smaller arcs using metallic splitter plates inside an arc chute.

   • Efficient cooling and quenching for high currents (up to 6,300A).

   • Most widely used in modern LV power distribution.

4. Air Blast ACB

   • Uses compressed air to blast and extinguish the arc.

   • Used in medium-voltage (MV) systems (up to 15kV).

   • Faster interruption but requires an air compressor.

B. Based on Operation Mechanism

1. Manual ACB

   • Operated by hand (lever or handle).

   • Used in small-scale applications.

2. Motorized/Electric ACB

   • Uses an electric motor or solenoid for remote operation.

   • Common in automated power systems.

3. Spring-Charged ACB

   • Uses a pre-charged spring mechanism for quick closing/opening.

   • Ensures fast tripping during faults.