Air Circuit Breaker (ACB) is an electrical device used to provide Overcurrent and short-circuit protection for electric circuits over 800 Amps to 10K Amps. These are usually used in low voltage applications below 450V.

there are two types of air circuit breakers

1.Air-Break Circuit Breakers

In Air-Break Circuit breaker the contact separation and arc extinction occur in air at atmospheric pressure i.e, the level of Hg at normal condition.High resistance principle is employed here.The arc resistance is increased to such an extent that the voltage drop across the arc becomes more than the system voltage and the arc gets extinguished at current zero of ac wave.Its employed in dc circuits and ac circuits up-to 12 kv.

2.Air-Blast Circuit Breakers

In Air- Blast Circuit Breaker it require an auxiliary compressed air system which supplies air to the breaker air receiver.When opening is required , compressed air is admitted to the arc extinction chamber.It pushes away the moving contacts . In doing so the contacts are separated and the air blast takes away the ionized gases along with it and assist arc extinction. Air blast extinguish the arc within one or two cycles and the arc chamber is filled with high pressure air,which prevents re strike. The air blast circuit breakers are used for up-to 220 kv and above. It uses high pressure air and is independent of current to be interrupted.

Air Circuit Breaker Demonstration

1. OFF button (O)
2. ON button (I)
3. Main contact position indicator
4. Energy storage mechanism status indicator
5. Reset Button
6. LED Indicators
7. Controller
8. “Connection”, “Test” and “isolated” position stopper (the three-position latching/locking mechanism)
9. User-supplied padlock
10. Connection “,” Test “and” separation “of the position indication
11. Connection (CE) Separation, (CD) Test (CT) Position indication contacts
12. Rated Name Plate
13. Digital Displays
14. Mechanical energy storage handle
15. Shake (IN/OUT)
16. Rocker repository
17. Fault trip reset button

post credits : electricaltechnology.org elprocus.com