Someone check me

[LHarrington]

We are going to transform 480 3ph to 230 3ph. Load is as follows
230v x 2.5(each leg) x 1.73 / 1000 = .999kva
3 kva transformer should cover just fine with room to grow, correct?
Also does the fact that the unit is VSD driven play a roll in sizing the trans correctly.
Only reason I have chosen 3kva is because I have one on the shelf.

LHarrington

 

[charlie b]

Your math looks good to me. I think that the only impact the VFD might have is to introduce harmonics. But with a 1 KVA load on a 3 KVA transformer, the extra harmonic currents should not cause the transformer to overload.