## Magnetic leakage

In a transformer it is observed that, all the flux linked with primary winding does not get linked with secondary winding. A small part of the flux completes its path through air rather than through the core (as shown in the fig at right), and this small part of flux is called as

(To minimize this leakage reactance, primary and secondary windings are not placed on separate legs, refer the diagram of core type and shell type transformer from construction of transformer.)

**leakage flux**or**magnetic leakage**in transformers. This**leakage flux**does not link with both the windings, and hence it does not contribute to transfer of energy from primary winding to secondary winding. But, it produces self induced emf in each winding. Hence,__. And due to this there will be__**leakage flux**produces an effect equivalent to an inductive coil in series with each winding**leakage reactance**.(To minimize this leakage reactance, primary and secondary windings are not placed on separate legs, refer the diagram of core type and shell type transformer from construction of transformer.)

## Practical Transformer with resistance and leakage reactance

In the following figure,

**leakage reactance**and resitance of the primary winding as well as secondary winding are taken out, representing a**practical transformer**.
Where, R

_{1}and R_{2}= resistance of primary and secondary winding respectively
X

_{1}and X_{2}=**leakage reactance**of primary and secondary winding resp.
Z

Z

The impedance in each winding lead to some voltage drop in each winding. Considering this voltage drop the

VE + jX

V

where, V

V

E

_{1}and Z_{2}= Primary impedance and secondary impedance resp.Z

_{1}= R_{1}+ jX_{1}...and Z_{2}= R_{2}+ jX_{ 2}.The impedance in each winding lead to some voltage drop in each winding. Considering this voltage drop the

**voltage equation of transformer**can be given as -V

_{1}=_{1}+ I

_{1}(R_{1}_{1}) --------primary sideV

_{2}= E_{2}- I_{2}(R_{2}+ jX_{2}) --------secondary sidewhere, V

_{1}= supply voltage of primary windingV

_{2}= terminal voltage of secondary windingE

_{1}and E_{2}= induced emf in primary and secondary winding respectively. (EMF equation of a transformer.)