Air Circuit Breaker (ACB)
An Air Circuit Breaker (ACB) is a type of circuit breaker that operates in low-voltage (LV) electrical networks and uses air as an arc-quenching medium. It is commonly used for protection and control of electrical power systems in industrial and commercial applications.
Working Principle of ACB
When a fault occurs, such as overcurrent, short circuit, or earth fault, the breaker detects the fault through its protective relay mechanism. It then trips, opening the circuit and interrupting the current flow. The arc produced during breaking is quenched in atmospheric air using arc chutes and blow-out coils.
Types of ACB
Based on Installation Design
- Fixed Type ACB
- Draw-out Type ACB
Fixed Type ACB – Permanently mounted in a panel or switchgear.
Draw-out Type ACB – Can be removed for maintenance or replacement without disturbing the circuit.
Based on Operating Mechanism
- Manually Operated ACB
- Electrically Operated ACB
Manually Operated ACB – Requires human intervention to switch ON/OFF.
Electrically Operated ACB – Uses a motorized mechanism for automatic operation.
Based on Arc Quenching Method
- Plain Break Type ACB
- Magnetic Blowout Type ACB
- Grid Type ACB (Arc Chute)
Plain Break Type ACB – Uses the natural flow of air for arc extinction.
Magnetic Blowout Type ACB – Uses magnetic fields to lengthen and cool the arc.
Grid Type ACB (Arc Chute) – Uses metallic plates to split and cool the arc, which is the most common design today.