Ideal Transformer

Definition of Ideal Transformer

An Ideal Transformer is an imaginary transformer which does not have any loss in it, means no core losses, copper losses and any other losses in transformer. Efficiency of this transformer is considered as 100%.

Ideal Transformer Model

Ideal Transformer Model is developed by considering a transformer which does not have any loss. That means the windings of the transformer are purely inductive and core of transformer is loss free. There is zero Leakage Reactance of Transformer. As we said, whenever we place a low reluctance core inside the windings, maximum amount of flux passes through this core; but still there is some flux which does not pass through the core but passes through the insulation used in the transformer. This flux does not take part in the transformation action of the transformer. This flux is called leakage flux of transformer. In an Ideal Transformer, this leakage flux is considered also nil. That means 100% flux passes through the core and linked with both primary and secondary windings of transformer. Although every winding is desired to be purely inductive but it has some resistance in it which causes voltage drop and I2R loss in it. In such ideal transformer model, the winding are also considered, ideal that means resistance of the winding is zero.

Now if an alternating source voltage V1 is applied in the primary winding of that Ideal Transformer, there will be a counter self emf E1 induced in the primary winding which is purely 180o in phase opposition with supply voltage V1.

For developing counter emf E1 across the the primary winding it draws electric current from the source to produces required magnetizing flux. As the primary winding is purely inductive, that current is in 90o lags from the supply voltage. This current is called magnetizing current of transformer Iμ

This alternating current, Iμproduces a alternating magnetizing flux Φ which is proportional to that electric current and hence in phase with it. As this flux is also linked with secondary winding through the core of transformer, there will be another emf E2 induced in the secondary winding, this is mutually induced emf. As the secondary is placed on the same core where the primary winding is placed, the emf induced in the secondary winding of transformer, E2 is in the phase with primary emf E1 and in phase opposition with source voltage V1.