How do you derive negative sequence impedance of an earthing transformer for 11 KV delta connected 10 MVA source transformer?
Negative sequence and positive sequence are the same for a transformer. You would derive using the same connections as done to calculate the positive sequence impedance. Usual…ly the test report will give positive, and often zero sequence impedances (sometimes left off, depending on the type of transformer as the zero sequence sometimes is the same as the positive sequence). The negative sequence is never given to my knowledge, because it is redundant and unnecessary test. (MORE)