If load loss of a transformer at full load is 100kW, the load loss at 50% load will be a) 50kW b) 75kW c) 25kW d) 100kW. i think its 25kW because load loss is inversely proportional to the square of loading percent. kindly explain . is it right.
Yes this is right. There are two losses in a power transformer: iron losses and copper losses. Iron losses in the core depend on the flux (hence the voltage) and the frequency. The copper losses come from I^2*R losses in the windings, so they depend on the load current. The flux in the core doesnt change when we change the load, only the current through the windings, so your reasoning is correct.
I'm guessing load loss is the same as copper loss, which is due to the resistance of the wire in the transformer. This loss is (I^2)(R wire) so the answer is c) 25 KW The current is 50% at 50% load, I^2 0.25
