PRACTICAL AND IDEAL TRANSFORMER

Ideal Transformer On Load.

 

As the transformer is loaded, current I2 flows in the secondary. When this current I2 flows through N2 it produces a flux φ2 . The polarity of φ2 is such that it opposes the main flux φM. The instantaneous effect of this opposition is that φM is reduced and instantaneously the induced voltage E1 in the primary is less than V1.

Because of this voltage difference, the primary current I1 increases, and as it passes through the primary turns N1, it produces an magneto motive force (mmf) to counter the instantaneous reduction in φM . The effect of this increased primary mmf is to bring the flux in the core back to the original value of φM.

Therefore when the supply voltage V1 is constant, despite changes in load current, the flux in a transformer remains at a constant value causing a voltage E1  to be induced in the primary windings and a voltage E2 to be induced in the secondary windings. This relationship neglects the magnetizing current demanded by the imperfections of the core.

PRACTICAL OR NON IDEAL TRANSFORMER

Transformation of energy is not perfect. Not all the flux produced by the primary winding links with the secondary, for example transformer has a leakage reactance. Establishing a flux involves the drawing of a magnetizing current. Pulsation’s of the flux  in the core produce a core loss due to HYSTERESIS and EDDY CURRENTS.

The continuing loss of energy to the core produces heat which must be removed from the transformer.