Switchgear Adjusting

Setting of Short Circuit Current depends on the specific make and model of MCCB. It depends on the fault level you are operating at.

Also there are two type of Short Circuit settings;

S -> short-circuit with inverse short time delay trip and trip characteristic with inverse time(I2t=constant)

I -> short-circuit with instantaneous trip

Correction! It is not short circuit release but instantaneous release in an MCCB. And, it is not 4 to 8 In in a Motor Duty MCCB but 12 In. Because, a motor's starting current is having a transient stage called 'magnetising inrush current, which is about 10 to 11 times the motor's full load current. If you set the MCCB's instantaneous release to anything less than this, it would spuriously trip during such inrush. So, in all motor duty MCCBs the instantaneous release is having a fixed setting of 12In or more.