(a) determine the AIC rating of a particular circuit breaker, or
(b) determine the amount of fault current that is available so that you can select the appropriate CB AIC rating?
Determining the rating of a CB is easy -- if it's not on the CB then look it up in the manuf. literature or just ask them.
If you're trying to calculate the available fault current, it can get complicated. There are quite a few variables that you'll need to know. If that's what you're trying to do, then more info is needed.
Also, look for a higher KAIC rating at lower voltages andlower KAIC rating at higher voltages on a given breaker which should be clearly labeled on the breaker nameplate.
it depends on what breaker are you using,is it MCCB or LVPCB,KAIC requirements also depend on your electrical load.what breaker size are you referring at?