Stator Creates a Rotating Magnetic Field: When an AC power supply is connected to the windings in the stator, it generates a magnetic field that rotates. In a three-phase induction motor, the alternating currents in the three windings, which are phase-shifted, naturally produce this continuously rotating magnetic field.
Rotor Current Induction: As this rotating magnetic field sweeps across the conductors (bars or windings) in the rotor, it induces an electromotive force (EMF) and, consequently, an electric current in the rotor.
Torque Production: The induced current in the rotor creates its own magnetic field. This rotor magnetic field then interacts with the stator's rotating magnetic field, producing a mechanical force (torque) that causes the rotor to spin.
The Role of Slip: For current to be induced in the rotor, there must be a relative motion between the stator's rotating magnetic field and the rotor conductors. If the rotor were to spin at the synchronous speed (the speed of the stator's rotating magnetic field), there would be no relative motion, no induced current, and therefore no torque.
