Electrical Engineering ⇒ Topic : Losses in a Transformer

A transformer is a static device and therefore has no rotational losses. Hence,major losses that occur in a transformer on load fall into two groups.

(1) Copper losses in the primary and secondary windings

                  Total copper loss =

(2) Iron losses in the transformer core due to the flow of hysteresis and eddy currents. The factors responsible for these two types of losses were already discussed in Chaps 4 and 10. In         actual practice, the maximum value of flux density in a transformer does not change by more than 2 percent between the no-load and the full-load. Therefore, the iron losses are usually     assumed to be constant at all loads in a given transformer

     Therefore total losses in a transformer =

LOSSES IN A TRANSFORMER

 Copper Loss

This loss occurs due to the ohmic resistance of the transformer windings.

It may be noted that copper loss at half of the full load indicates one fourth of that at full load. The copper loss can be found from short circuit test of the transformer

Core Loss or Iron Loss

This loss includes both hysteresis loss and eddy current loss. Since the core flux remains almost practically constant for all loads, the core loss is practically the same for all loads. It can be found from open circuit test of the transformer.

                                       ............... (1)

                                ................ (2)

Hysteresis loss is minimized by using steel of high silicon content for the core. Using very thin laminations of core, minimizes eddy current loss. This loss is measured from DC test of the transformer.