im in mccb

Is it Im or Icm?

Icm = Rated short-circuit making capacity

Extract from IEC 60947-2:

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4.3.5.1 Rated short-circuit making capacity (Icm)

The rated short-circuit making capacity of a circuit-breaker is the value of short-circuit making capacity assigned to that circuit-breaker by the manufacturer for the rated operational voltage at rated frequency and at a specified power factor for a.c., or time constant for d.c. It is expressed as the maximum prospective peak current.

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- MS

It may be the setting of magnetic trip.Then what is Ir?.

I am. I^,m in mccb. That is correct.

Please refer www.electrical-installation.org/lv switchgear functions and selection In-rated current Ics-rated breaking capacity Icm-rated making capacity Icu-ultimate SC breaking capacity(fault level) Icw-short time withstand current Ir(Ith)-over current Im-Short circuit current You can also find types B,C,D mcb's tripping characteristics Compare Fuses type g,a,G,M