10kva problem

searley · May 17, 2009

how do i calculate 10kva so i can work this question out ?

a 3 phase 10kva transformer has a pf=0.9.calculate the line current for the transformer.

will i use sqaure root to work this question out ? are just x them all togeather?

msb2003 · May 17, 2009

I don't think you have enough information there, what voltage are you expected to use and is it star or delta configeration?

searley · May 17, 2009

i take it is 50hz.i worded the question the way it is on the sheet.

Andy™ · May 17, 2009

i take it is 50hz.i worded the question the way it is on the sheet.

frequency has nothing to do with this question - as above, we need more information to give you an answer

but at a quick guess, id say answer may be 13A?

searley · May 17, 2009

16amps on the answer sheet.tryed some other questions and they did`nt work out but where close to what i got.

web site was swindon massive

Andy™ · May 17, 2009

16amps on the answer sheet.tryed some other questions and they did`nt work out but where close to what i got.web site was swindon massive

really need more info on this. even assuming PF of 1, i get 14.45A

BUT: if it was 10KW and not 10 KVA, i get 16A

so working on that

10/0.9 = 11.11KVA

......................................kVA X 1,000

Three-phase amps = -----------------------------------------

........................................ 1.732 X Line to Line voltage

so 11.11x1000 / 1.732 x 400

= 16A per phase

or, the even easier way

KVA / 0.692 = A per phase

so 11.11 / 0.692 = 16A

(the 0.692 is the 1000, 1.73 and 400 all into one number)

or at least i think this is right