(i) Copper losses: This loss is encountered in shell part (P & S co transformer, because of heating effect of current. To minimize this loss, in transformer high current coil is always made of thick wire. Copper loss ∝ f 2 where f = frequency of supply.
(ii) Eddy current losses: This loss is occurred in iron core of transformer, hence it is also named as Iron losses.
Reason : Iron core is placed in time varying magnetic field, because of which eddy currents are generated and energy is lost in the form of heat.
To minimize this loss plane laminated iron core is used instead of a single bulk piece. Iron loss ∝ f 2.
(iii) Hysteresis losses: This occurs in core of transformer because it is placed in alternating magnetic field and goes under cycle of magnetization and demagnetization.
To minimize this loss , core of transformer must be made of such ferromagnetic materials which have low coercivity, high magnetic susceptibility and high permeability, less area of hysteresis loop.
For this soft iron is suitable, therefore core of transformer is made of soft iron. Nowadays it is made of Permalloy (Fe – 22% Ni – 78%)
(iv) Flux leakage: There is air gap between the two coils, so flux of the two coils leaks through this air gap. To minimize this leakage, both the coils are wound on a common core whose two ends are joined so that coupling becomes almost tight (K → 1) and closed path of magnetic field lines are formed itself within the core.
Uses of Transformer
A transformer is used in almost all A.C. operations e.g.
(i) in voltage regulator for T.V., Refrigerator, Computer, Air conditioner etc.
(ii) in the induction furnaces.
(iii) a S.D.T. is used for welding purposes.
(iv) in the transmission of A.C. over long distances.