Operating principle: - As soon as the primary winding is connected to the single phase AC supply, an AC current starts flowing through it.

Working:- When an alternating voltage is applied to a primary winding, an alternating current I, flows in it producing an alternating flux in the core.

As per Faraday’s law of electromagnetic induction,

e1= N1 dф/ dt

e1= e.m.f induce

N1= number of turns in primary winding

Assuming leakage flux be negligible, almost whole flux in primary winding links with the secondary

$E_2=-N_2 dф/ dt$

Thus, energy is transferred from primary winding to secondary

EMF EQUATION

An alternating current flows in winding producing a sinusoidal varying flux ф in the core

Ф=фmsinwt

∴ e1= -N1 dф/dt =N1 d/dt (фmsinwt)

= -N1 d/dt (фmsinwt)

=-N1 фm wcoswt

∴ +N1 фm wsin (wt=90o)

∴ 2πf фm sin (wt-90o) N1

Maximum value= 2πf фm N1

Hence, rms value of induced e.m.f in primary winding is

1 = Emax/√2 = 2πфmN1/√2 = 4.44 fфmN1

Similarly, for N2E2

E1/N1 = E2/N2 = 4.44fфm