Air Circuit Breaker (ACB)

An air circuit breaker (ACB) is a type of circuit breaker that uses air as the interrupting medium to interrupt and break the circuit during a fault or overload condition. An air circuit breaker is designed to overcome defects and safeguard the machine before it breakdowns.


ACBs consist of a set of contacts that open and close when the breaker is operated. The contacts are housed in a metal enclosure, which is filled with air as the interrupting medium. The breaker is designed to quickly and safely interrupt the circuit when a fault occurs, preventing damage to the equipment and reducing the risk of electrical hazards.


ACBs can be manually operated, typically with a handle or lever, or can be automatically tripped by protective relays that sense fault conditions.


The main function of the air circuit breaker is to:    

  • Open and close a 3-phase circuit, manually or automatically
  • Open the circuit automatically when a fault occurs. Faults can be of various types – under or over voltage, under or over frequency, short circuit, reverse power, earth fault, etc. 
  • The main feature of ACB is that it dampens or quenches the arcing during overloading.

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