OPERATING PRINCIPAL OF TIANSFORMER

Transformer is a static electrical machine which transfer electrical power from one circuit to another circuit . The  winding diagram of transformer is shown in figure.

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When the primary winding is supply by AC source then the current Io flows and magnetic flux Qm produced in the iron core the magnetic flux links the secondary winding so according to faradays law of electro magnetic induction EMF E2 induced in secondary winding as the magnetic flux also links the primary winding. the average value of EMF induced in secondary winding is
          

                         E2=N2dQ/dT


LOSSES IN TRANSFORMER

There are two types of loss  occur in transformer .which are 
1) iron loss
2) copper loss

IORN LOSS

the losses which occur in core of transformer is called iron loss .This loss is mainly due to heating of iron core. iron loss are two types such as eddy current loss and hysteresis loss.so

iron loss=eddy current loss +hysteresis loss

copper loss

the losses which occur in the winding of the transformer is called copper loss this losses is mainly due to the generating in the resistance of winding transformer .copper loss also depend on the load.

copper loss=square of current. resistance=I2R

  so the total losses of transformer equal to sum of  iron loss and copper loss

Wt=Wi+Wc

efficiency of transformer

The ratio of output power of transformer to the input power of transformer is called efficiency of transformer . the efficiency of transformer is never equal to 100% because there are some losses within the transformer.

efficiency=output power / input power 

note: iron loss donot  depend load but copper loss depend upon load.

the efficiency of transformer  is maximum when iron loss equal to the copper loss.