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
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.