Single-phase Transformers

Thread Starter


Joined Oct 10, 2004
hey, I am really stuck on this question, if any of you could help me out with this i would be most grateful..

A 20-kVA, 3.3-kV/240-V transformer has a core loss of 180 W, as indicated by a wattmeter during an open-circuit test. During a short-circtuit test at rated (full-load) current, the wattmeter indicated 540 W. calculate the full-load efficiency at unity power factor.

a) Calculate the full load efficiency at 0.8 lagging power factor.

B) Calculate the efficiency at 75% full load and 0.80 lagging power factor.

c) Calculate the maximum efficiency for the tranformer.

thanks in advance :)