I assume all three are in parallel? Why can't you select a base MVA and use that to determine each transformer %Z in pu based on the base MVA. Then you take the parallel comination of the three impedances and calculate the fault at the secondary relative to 240 volts. You would also need a...
You also need to assume, since it does not say on the diagram, that you are neglecting the cable impedance and feeder length. You have a motor contribution to the fault as well limited my cable impedance and motor impedance. Try your fault calculation for the first transformer for the fault...
The H0 connection was originally grounded, but was removed due to tripping of a 50G that was on the feeder breaker. The relay was tripping during magnetization of the transformer...zero-sequence currents. I've since replace the 50G with a 51G (time delay). I think I can skin this cat by...
I am looking for some insight this configuration we are experiencing problems with: I have a distribution transformer that is configured wye-wye, 4160-480/277, 3W, 3P. No neutral is brought out from my switchgear to this transformer, only an equipment ground. The transformer secondary has the...
