 WAZIPOINT Engineering Science & Technology: Transformer with Resistance and Leakage Reactance Calculation

## What do you mean by Transformer Resistance and Leakage Reactance?

The Transformer resistance means the resistance of the primary and secondary winding of the transformer.

Transformer Leakage Reactance means there is some magnetic leaking in both of the primary and secondary windings that should be equal to inductive coils connected in both primary & secondary windings.

The figure above shows the primary and secondary windings of a transformer with reactance taken out of the windings.

The primary impedance is given by
Z1 = sqr(R12+X12)

Similarly, secondary impedance is given by
Z2 = sqr(R22+X22)

The resistance and leakage reactance of each winding is responsible for some voltage drop in each winding.

The primary leakage reactance drop is I1X1(usually 1 or 2% of V1).

Hence,
V1= E1+ I1(R1+jX1) =E1+I1Z1

Similarly, I2R2 and I2X2 drops in secondary 2R2 and I2X2 drops in secondary which combine with V2 to give E2.
E2 = V2 + I2(R2+jX2) =V2+ I2Z2

It may be noted that leakage reactance can also be transferred from one winding to the other in the same way as resistance.