– Thermal Protcetion against ” Overload faults ” : it can be adjusted ” Ir : 0.4 to 1 x In “, where ” In ” is the nominal current of ACB like : 2500A or 3200A or 4000A, so, if we adjusted it at ” 0.5 ” for ” ACB – 4000A “, the thermal protcetion value is ” Ir = 0.5 x 4000 = 2000A “
– Magnetic Protection for ” Short Circuit Faults ” : it can adjusted ” Isd : 1.5 to 10 x Ir ” or for some manufacters to ” 12 “, so, if we adjusted for the same ACB at ” 6 “, the magnetic protection value is ” Isd = 6 x 2000 = 12000A “.
– Earth Fault Protection against direct fault between any phase and the protection line, it can be adjusted ” Ig : 0.3 to 1 x In “, so, if we adjusted it for the same ACB at ” 0.7 “, the earth fault protection value is ” Ig = 0.7 x 4000 = 2800A “.
-Residual Protection against ” Residual Faults ” that means against indirect fault where the fault current's value is normaly small ( a few Amps ), it can asjusted ” IΔn : 0.5 to 30A “.
– Instantaneous Protection against ” Short Circuit Faults ” when the fault's current value will be very big, and in the same time we want that ACB trip quickly without delaying, it can adjusted ” Ii : 2 to 15 x In ” and we can also switched-off, so, if we adjusted it for the same ACB at ” 6 ” the instantaneous protection value is ” Ii = 6 x 4000 = 24000A “.
In some ACB there's also a ” Timing Delay ” for the thermal protection and for the magnetic protection, where the ” Timimg delay ” for thermal protection can be adjusted is ” Seconds “, but the ” Timing Delay ” for the magnetic protection can be adhusted in ” mili-Seconds “, and we use these ” Timing Delay ” in ACB to realize the ” Discrimination or Selectivuty ” between 2 ACB's or between ACB and MCCB .