1. The problem statement, all variables and given/known data A 50 kVA 6360 V/240 V, 50 Hz, transformer is tested on open circuit and short circuit to obtain its efficiency. The results of the tests are as follows: Open Circuit: Primary Voltage 6360 V, Primary current 1.0 A, Input power 2 kW. Short Circuit: Voltage across primary 280 V, Current in secondary 175 A, Input power 1kW power factor at 0.8 lagging 3. The attempt at a solution So far I've calculate the impedances using the open circuit and short circuit equations, and I'm having trouble getting the power equations. I've used P(open circuit) = P(input)*I(open circuit)*cos(theta) where cos(theta) = PF I've used P(short circuit) = P(input)*I(short circuit)*cos(theta) And then P(output)/(P(output) + P(open circuit)+P(short circuit)), and I'm getting an efficiency of ~61%. I'm pretty sure this is wrong.