I'm a bit confused on the term current rating in an ac generator. Is it the one in that I can get in the formula:

kW= V*I*PF*sqrt(3) ? or the one in kW= V*I*sqrt(3)? The problem is the data that I have is V, PF, kVA only. I can compute the kW using those data but I'm abit confused on those formulas.

Also, I've read in some books that there are times that if the generator is 3 phase, the formula has a sqrt(3) why is that so?

Thanks!