WHAT IS ACB?

ACB stand for Air Circuit Breaker. It is a Electrical Protection device. It is designed to overcome the defects and safeguard the machine before it breakdowns. ACB is low voltage(up to 1000 volt) power distribution switch gear. 


Main function is -  Open and close circuit by manually or automatically & Open the circuit automatically when fault occurs. Fault can be different types- overload, short circuit, earth fault, over/under frequency etc.




How To Setting an A.C.B. 


Micro logic controller 

In = Nominal current

1. Overload setting

Ir = (0.4 to 1)In

2. Short circuit current

Isd = (1.5 to 10)Ir

3.Earth / Ground Fault

Ig = (0.4 to 10)In

4. Instantaneous Fault

Ii = (2 to 15)In


Example: 


2500 Amp  A.C.B

In = 2500 A


1. Overload setting

Ir = 0.8 * 2500 = 2000 Amps.

2. Short circuit current

Isd = 1.5 * 2000 =3000 Amps.

3. Earth/Ground Fault

Ig = 0.4 * 2500 = 1000 Amps.

4. Instantaneous Fault Current

Ii = 2 * 2500 = 5000 Amps.