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## Homework Statement

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.