Losses in a Transformer

LOSSES IN A TRANSFORMER

The transformer is a static device, there are no friction (or) windage losses. Then losses occurs are

 (i) Core (or) iron loss

(ii) Copper loss

Core (or) iron loss

It includes both hysteresis loss and eddy current loss. Because the core flux in a transformer remains practically constant for all loads. The core loss is practically the same at all loads.

Hysteresis loss w_h = ɳβ_max^1.6ƒV watts

Eddy current loss w_e = Pβ_max² ƒ² t² watts

These losses are minimized by using steel of high silicon content for the core and by using very thin laminations. The iron (or) core loss is found from the open circuit test.

Copper loss:

This loss is due to the ohmic resistance of the transformer windings. Total Cu loss = I₁²R₁ + I²R₂ = I₁²R₀₁ + I₂²R₀₂.It is clear that C_u loss is proportional to (current)². The copper loss is found from the short-circuit test.

Efficiency of a transformer:

The efficiency of a transformer at a particular load and power factor is defined as the output divided by the input.

Efficiency = Output/Input

(or)

Efficiency = output/output + losses