The rotor of an induction motor rotates due to the principle of electromagnetic induction. When an alternating current (AC) is applied to the stator windings of the motor, it creates a rotating magnetic field. This rotating magnetic field induces currents, known as eddy currents, in the rotor conductors. According to Lenz’s law, these eddy currents create their own magnetic field which interacts with the stator’s magnetic field. The resulting interaction between these magnetic fields exerts a torque on the rotor, causing it to rotate in the direction of the rotating magnetic field generated by the stator.
The rotor of an induction motor rotates slower than the stator field primarily due to slip. Slip is the difference between the synchronous speed of the rotating magnetic field generated by the stator and the actual rotational speed of the rotor. The synchronous speed depends on the frequency of the AC supply and the number of poles in the motor. The rotor rotates at a speed slightly less than the synchronous speed because it requires this slip to induce the currents necessary for torque production. The amount of slip determines the motor’s efficiency and ability to generate torque.
The principle of rotation of an induction motor is based on the interaction between the rotating magnetic field generated by the stator and the induced currents in the rotor. When AC voltage is applied to the stator windings, it creates a rotating magnetic field that cuts through the rotor conductors. As a result, currents are induced in the rotor due to electromagnetic induction. These currents interact with the stator’s magnetic field, producing a torque that causes the rotor to rotate. This rotating motion enables the induction motor to perform mechanical work, such as driving fans, pumps, or other machinery.
It is impossible for the rotor of an induction motor to rotate at the same speed as the magnetic field generated by the stator due to the nature of induction motor operation. The rotor’s speed is inherently slower than the synchronous speed of the stator’s rotating magnetic field because of slip. If the rotor were to rotate at the synchronous speed, there would be no relative motion between the stator’s magnetic field and the rotor conductors, resulting in zero induced currents and, consequently, no torque production. Therefore, slip is necessary to maintain the electromagnetic interaction between the stator and rotor, allowing the motor to develop torque and operate effectively.