A 630 kVA, 11kV/400V transformer. Rp, Xp, Rs, Xs, Rc, and Xm are given. How to find secondary and primary? Do I need to calculate the total impedance referred to the primary and secondary or can I calculate currents without it?
Given its capacity this is almost bound to be a three phase transformer. You need to know the connection of the primary and secondary windings (Y or Δ) to determine the windings' currents. You can basically calculate the rated currents from the kVA rating and voltage without using the impedances, eg. Ip primary rated current 630/(11 x 3 x √3) which assumes a 3 phase transformer with a Y-connected primary. Edit: If the capacity value is totally unreliable then there's no way you can find the rated current with only the other values you give. You need the load impedance as well.! This applies whether it's a single or a three phase unit I'm afraid. Why do you bother me with useless data? If you do this kind of thing to your employer in later life you'll rightfully get scalded!! On top of that you don't even initially say please or later apologise for such a gaffe.
