Calculating Losses in Transformers

dear,.

no load losses are same for all load & pf conditions.

just run the transformer on no load, measure the power consumption for say 10 hrs, then power consumption /1o hrs. = no load losses of the transformer you have

see the test report of manufacturer - the above figures shall match.

As per the test report of manufacturer, Copeer load losses = say K units at unity pf, 100%load and at 75deg. C

then,

Copper load losses at load say L% = (L%/100)² *K /pf units of kwh.

add the above figures for total losses at particular load.

This is under grad EE: you have to perform a series of open circuit and short circuit tests to develop a equivalent circuit model of the transformer. You should make all calculations in per-unit notation. If you have a three-phase xfmr, you'll be working with a per-phase model in per-unit notation. Your circuit model will help you find the parasitic losses, power factor, phase angle, apparent turns ratio, efficiency, magnetizing current and inrush current.

This is something you should be able to accomplish at bench scale. You'll need a variable voltage source of the rated frequency for the XFMR and at the very minimum you need a good multi-meter and o-scope. A clamp-on amp meter or digital watt/WH meter would also be handy.

This is really fun if you've built your own xfmr out of junk parts. An old motor, a bicycle/motorcycle frame, concrete rebar. Once you see how easy it is to screw up a transformer design, you'll have a lot of appreciation for the people that design these for a living.

JC