Air Circuit Breaker commonly known as automatic air switch, the distributor is automatically breaking the circuit when overload, short circuit or undervoltage circuit occurred. It is one of the important low-voltage AC and DC power distribution system protection appliances.

Capacity of the air circuit breaker should be selected include the following:

Step 1: Selecting an air circuit breaker rated current, i.e. the current through the main contact allows the long-term, according to the working current of the circuit selection.

Step 2: The maximum allowed by the long-term operation is not selected when the current release, i.e., release. By working current of the circuit is to choose.

Step 3:  When an instantaneous release operation selected setting current setting or multiple, i.e., it does not release operation, the instantaneous values ​​of the maximum current allowed.