**1. Effect of Leakage Reactance** Uptill now it is assumed that the entire flux produced by the primary links with the secondary winding. But in practice it is not possible. Part of the primary flux as well as the secondary flux completes the path through air and links with the respecting winding only. Such a flux is called leakage flux. Thus there are two leakage fluxes present as shown in the Fig. 1.

Fig .1 Individual impedance |

The flux Φ

_{L1}is the primary leakage flux which is produced due to primary current I_{1}. It is in phase with I_{1 }and links with primary only. The flux Φ

_{L2}is the secondary leakage flux which is produced due to current I_{2}. It is in phase with I_{2 }and links with_{ }the secondary winding only. Due to the leakage flux Φ

_{L1}there is self induced e.m.f. e_{L1}in primary. While due to leakage flux Φ_{L2}there is self induced e.m.f. e_{L2}in secondary. The primary voltage V_{1 }has to overcome this voltage e_{L1}to produce E_{1}while induced e.m.f. E_{2}has to overcome e_{L2}to produce terminal voltage V_{2}. Thus the self induced e.m.f.s are treated as the voltage drops across the fictitious reactance placed in series with the windings. These reactances are called leakage reactance of the winding. So X

and X

Then the total leakage reacatance referred to primary is X

X

While the total leakage reacatnce referred to secondary is given by ,

X

And K = N

_{1}= Leakage reacatnce of primary winding.and X

_{2}= Leakage reactance of secondary winding. The value of X

_{1}is such that the drop I_{1}X_{1}is nothing but the self induced e.m.f. e_{L1}due to fluxΦ_{L1}. The value of X_{2}is such that the drop I_{2}X_{2}is equal to the self induced e.m.f. e_{L2}due to flux Φ_{L1}. Leakage fluxes with the respective windings only and not to both the windings. To reduce the leakage, as mentioned, int eh construction both the winding's are placed on same limb rather than on separate limbs.

__1.1 Equivalent Leakage Reactance__

Similar to the resistances, the leakage reactances also can be transferred from primary to secondary or viceversa. The relation through K

Let X^{2 }remains same for the transfer of recatnaces as it is studied earlier for the resistances._{1}is leakage reactance of primary and X_{2}is leakage reactance of secondary.Then the total leakage reacatance referred to primary is X

_{1e}given by,X

_{1e }= X_{1}+ X_{2}**'**where X_{2}**'**= X_{2}/K^{2 }While the total leakage reacatnce referred to secondary is given by ,

X

_{2e}= X_{2}+ X_{1}**'**where X_{1}**'**= K^{2 }X_{1}And K = N

_{2}/N_{1}=transformation ratio

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