Working Principle of Air Circuit Breaker in English and Hindi

An essential part of electrical systems, the air circuit breaker is intended to safeguard circuits and equipment by cutting off current flow in the event of failures or overloads. It is essential for guaranteeing the operation and safety of electrical networks. In-depth examination of the components and functioning of air circuit breakers will be done in this article as we dive into their working theory.

What is an Air Circuit Breaker?

An air circuit breaker (ACB) is a type of circuit breaker that uses air as the medium for arc extinction. It consists of various components, including the frame, operating mechanism, contacts, trip unit, and arc quenching chamber. The ACB is typically found in low voltage installations and is capable of handling large currents.

Working Principle of a Air circuit Breaker

The normal operating state and abnormal operating circumstances are the two distinct stages of an air circuit breaker’s operation. The contacts of the breaker stay closed under normal circumstances, enabling electricity to pass across the circuit. However, the breaker trips and shuts off the circuit when a malfunction or overload happens.

Contact Closing

When the ACB is in the closed position, the moving contact is in contact with the fixed contact, allowing current to flow through the circuit. The operating mechanism ensures secure contact between the contacts and prevents any accidental openings.

Operation during Faults

In the event of a fault, such as a short circuit, excessive current flows through the circuit. This excessive current is detected by the trip unit, which immediately sends a signal for the breaker to trip. The trip unit is usually equipped with current sensing devices or protective relays, which monitor the current levels and actuate the breaker.

Arc Extinction

Once the trip signal is received, the operating mechanism initiates the opening of the breaker contacts. As the contacts start to move apart, an arc is formed due to the high current flowing through the gap. The arc is then quenched using the air in the arc quenching chamber. The high-speed air flow generated by the opening contacts extinguishes the arc, ensuring safe interruption of the circuit.

Contact Opening and Closing Speed

The speed at which the breaker contacts open and close is an important factor in its operation. It is crucial for the contacts to separate quickly during fault conditions to extinguish the arc promptly. Similarly, during contact closing, the contacts should make a firm and stable connection to prevent any arcing or sparking.

Advantages of Air Circuit Breakers

Air circuit breakers offer several advantages, making them widely used in electrical installations:

  1. High Breaking Capacity: ACBs can handle large currents and have high breaking capacity, ensuring reliable protection of electrical circuits.
  2. Ease of Maintenance: ACBs are easy to maintain and service, allowing for quick inspection and replacement of components if required.
  3. Flexibility: Air circuit breakers can be easily adjusted and customized to suit specific applications, providing flexibility in system configuration.
  4. Safety: The arc quenching mechanism in ACBs ensures the interruption of fault currents in a safe and controlled manner, minimizing the risk of electrical accidents.
  5. Longevity: With proper maintenance, ACBs have a long operational life, providing extended protection to electrical systems.


The appropriate use of air as a medium for arc extinction is crucial to the operation of air circuit breakers. For electrical safety and protection in many applications, it is essential to understand how an ACB is built and functions. Because of their benefits, air circuit breakers are a crucial part of contemporary electrical systems.

Leave a Comment