Losses in a transformer | Types | Classification of losses in transformer

Classification of Transformer losses

There are mainly two types of losses in transformer. They are:

1. Core losses or Iron losses and
   1. Hysteresis loss and
   2. Eddy current loss
2. Copper losses

Apart from these two types there are other losses are present in
the transformer namely, stray load loss and dielectric loss. These are small and hence usually be neglected.

Types of losses in Transformer

Iron or Core Losses in Transformer

Hysteresis loss

Hysteresis loss occurs due the reversal of magnetic
field due to the applied alternating current in the transformer core. It depends mainly on the material of the core and this loss can be reduced by using high grade core material. Cold rolled grain oriented (CRGO) silicon steel is commonly used as transformer core to reduce Hysteresis loss. The Hysteresis loss is mathematically represented as,

W_h=K_hB_m^xfv
Go to: hysteresis losses in electrical machines  for full text on hysteresis loss.

Eddy current loss

Eddy current loss occurs due to the flow of eddy currents in the core material. To reduce the eddy losses thin laminations which were insulated from each other are used.

Eddy current loss = K_ef²B²_max

Copper losses or Ohmic losses

The copper losses occur in the windings of the transformer due to their internal resistance. If R is the total resistance of the windings of the transformer and I is he current drawn, then the copper loss is I²R (W). As the copper loss is dependent upon the current which changes with change in load making the copper loss a variable loss. Hence copper losses are variable and increases with increase in load current.

Stray load losses

Stray load loss is an eddy current loss in which the eddy currents are caused by leakage fields. The leakage fields present in transformer induce eddy currents in conductors, tanks, channels, bolts etc. and these eddy currents give rise to stray load losses.

Dielectric losses

This loss occurs due to the insulating materials used in transformer namely, the oil in the transformer and coil insulations used for the primary and secondary windings of the transformer.

Also Read:

Construction and Parts of a Transformer
Core materials used in Transformer
Transformer