LOSSES OF TRANSFORMER 

• COPPER LOSSES 

These loses are in primary and secondary winding of a transformer it can be detected by short ciruit test
Copper loss is I²R loss, in primary side it is I₁²R₁ and in secondary side it is I₂²R₂ loss, where I₁ & I₂ are primary and secondary current of transformer and R₁ and R₂ are resistances of primary & secondary winding. As the both primary & secondary currents depend upon load of transformer, copper loss in transformer vary with load.

• CORE IRON LOSSES 

Their are two types of core losses 

1. EDDY CURRENT LOSSES 

In transformer, we supply alternating current in the primary, this alternating current produces alternating magnetizing flux in the core and as this flux links with secondary winding, there will be induced voltage in secondary, resulting current to flow through the load connected with it. Some of the alternating fluxes of transformer; may also link with other conducting parts like steel core or iron body of transformer etc. As alternating flux links with these parts of transformer, there would be a locally induced emf. Due to these emfs, there would be currents which will circulate locally at that parts of the transformer. These circulating current will not contribute in output of the transformer and dissipated as heat. This type of energy loss is called eddy current loss of transformer.

2.HYSTERESIS LOSSES

AT every half cycle the magnetic flux changes its direction , so this is the reason for hystereisis losses 

Physical Explanation of Hysteresis Loss

The magnetic core of transformer is made of ′Cold Rolled Grain Oriented Silicon Steel′. Steel is very good ferromagnetic material. This kind of materials are very sensitive to be magnetized. That means, whenever magnetic flux would pass through, it will behave like magnet. Ferromagnetic substances have numbers of domains in their structure. Domains are very small regions in the material structure, where all the dipoles are paralleled to same direction. In other words, the domains are like small permanent magnets situated randomly in the structure of substance. These domains are arranged inside the material structure in such a random manner, that net resultant magnetic field of the said material is zero. Whenever external magnetic field or mmf is applied to that substance, these randomly directed domains get arranged themselves in parallel to the axis of applied mmf. After removing this external mmf, maximum numbers of domains again come to random positions, but some of them still remain in their changed position. Because of these unchanged domains, the substance becomes slightly magnetized permanently. This magnetism is called " Spontaneous Magnetism". To neutralize this magnetism, some opposite mmf is required to be applied. The magneto motive force or mmf applied in the transformer core is alternating. For every cycle due to this domain reversal, there will be extra work done. For this reason, there will be a consumption of electrical energy which is known as Hysteresis loss of transformer.

LEAKAGE FLUX 

ALREADY DISCUSSED 

EFFICIENCY OF A TRANSFORMER