How Many Types of Losses in Transformer?

In this tutorial, we are going to learn about Losses in Transformer.

There are two types of losses which may occur in transformer.

  1. Iron losses or core losses or constant losses.
  2. Copper losses or I2R losses.

Core or Iron losses: This loss includes Hysteresis loss and Eddy current loss. These losses are independent of load and are also called constant load losses. This loss can be determined by open circuit test on transformer.

Loss: Since the flux in transformer is alternating power is required for the continuous reversal of elementary magnets which the iron is composed. This loss is known as hysteresis loss.

        Hysteresis loss = KnFbM1.6V (watts)

Eddy current losses: – Since the flux in the transformer core is alternating, it links with the magnetic material of the core. This induces EMF in the core and circulates eddy currents. Power is required to maintain these eddy currents. This power is dissipated in form of heat and known as eddy current loss.

Eddy current loss = K e V f2 t2 BM2 (Watts)


       K e= co-efficient of eddy current and its value depends upon the nature of magnetic material.

      B m= Maximum value of flux density (WB/m2)

      T = Thickness of lamination (m)

      F = Supply frequency (Hz)

      V = Volume of magnetic material (m3)

This loss can be minimized by making the core of thin laminations.

    Iron or core loss is found from the open circuit (O.C) test (the input of transformer when on no load measures the core loss)

Copper losses: – These losses are due to the OHMIC resistance of the transformer windings.

  Total copper losses = I1 2R2 = I12R01 + I22R02

It is clear that copper loss is proportional to (Current)2 or KVA2. In other words, copper loss at half the full load is one-fourth of that of full-load. The value of copper loss is found from the short circuit test.

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