Working principle of induction motor: * When the motor is excited with three-phase supply, three-phase stator winding carries three-phase currents & produces a rotating magnetic field of constant magnitude and rotates at synchronous speed. * This changing magnetic field is cut by the rotor conductors and induces emf in them according to Faraday‟s laws of electromagnetic induction. As these rotor conductors are shorted, the current starts to flow through these conductors. * These current carrying rotor conductors are now in the rotating magnetic field produced by stator. Consequently, mechanical force acts on rotor conductors. The sum of the mechanical forces on all the rotor conductors produces a torque, which tend to move the rotor in the same direction as the rotating magnetic field.