_{1}’).
Reactance drop is the voltage drop in the reactance of the winding which is in quadrature with the current(IX_{1}’).
Impedance drop is the vector sum of the resistance drop and the reactance drop.

_{1} = N_{1}/N_{2} [I_{2}(r_{2}’+jx_{2}’)+V_{2}]

V_{2} = N_{2}/N_{1} [V_{1} -I_{1} (r_{1}’ + jx_{1}’)]

^{2}=1000 w

Efficiency =(Output power)/(Input power) =(E_{2} I_{2}×P.F)/(E_{2} I_{2}×P.F+Losses)

= (E_{2} I_{2} cos∅)/(E_{2} I_{2} cos∅+W_{1}+I_{1}’ R1+I_{2}’ R_{2} )

Where E_{2} =Secondary voltage.

I_{2} = Secondary current.

I_{1} =Primary current.

R_{1} =Primary resistance.

R_{2} = Secondary resistance.

W_{1} =Iron losses.

When, R= Equivalent resistance in terms of secondary.

X =Equivalent resistance in terms of secondary.

E = Induced e.m.f. of secondary.

Φ = Phase difference between voltage and current.

I =Full load current.