Induction Motor as a transformer:

· As we know for a transformer two windings must be magnetically coupled.

· When primary winding is connected to an AC supply emf gets enduced into the secondary as per the principle of induction.

· Induction motor also operates on the principle of induction as when stator winding is connected to an AC supply then an AC voltage will be generated in the rotor winding hence we are calling it as an rotating transformer.

· Transformation Ration is given as:

K=E2/E1=N2/N1 at N=0 or S=1


E1=Stator emf per phase

E2=Rotor emf per phase

N2=Number of rotor turns

N1=number of stator turns

v Torque Equation of Induction motor:

· We can Produce torque in the induction motor with the help of below parameters;

i) The rotor power factor

ii) The rotor Current

iii) Part of rotating magnetic field which induces emf in the rotor winding.

Combinely we can write it as:-

T α ΦT2rCosΦ2r


Φ=Flux induced in induction motor

I2r=rotor Current

cosΦ2r=Rotor power factor