Efficiency of Transformers

In practice, some energy is always converted into heat in the core and the windings of the transformer. As a result, the electrical energy output across the secondary is less than the electrical energy input.

The efficiency of a transformer is given by

η = Energy output / Energy input × 100%

η = Power output / Power input × 100%

The efficiency of a transformer is less than 100%.

In a transformer the energy losses result from:

  • Resistive heating in copper coils - cooper loss
  • Eddy current losses in form of heating of iron core - Eddy current loss
  • Magnetization heating of the core during repeated reversal of magnetization - hysteresis loss.
  • Flux leakage from the core.