Final answer:
The 3-phase induction motor operates on the principle of electromagnetic induction and requires a 3-phase power supply to create a rotating magnetic field. A change in magnetic flux induces an emf in the rotor, generating current that creates its own magnetic field, leading to the rotation of the rotor.
Step-by-step explanation:
Operation of a 3-Phase Induction Motor
Induction motors, particularly a 3-phase induction motor, operate on the principle of electromagnetic induction. For a 3-phase induction motor to operate, it requires a 3-phase power supply, which consists of three alternating currents that are offset in phase by 120 degrees. This setup creates a rotating magnetic field within the motor that is essential for its operation.
Electromagnetic induction occurs when a coil in the stator, supplied with 3-phase current, produces a rotating magnetic field. This field interacts with conductors on the rotor. According to Faraday's Law of electromagnetic induction, a change in magnetic flux induces an electromotive force (emf). In this case, the relative motion between the rotating magnetic field and the rotor conductors produces an induced emf, which in turn generates current in the rotor.
The induced current in the rotor creates its own magnetic field, which opposes the original magnetic field, as described by Lenz's Law. The interaction between these magnetic fields produces torque which makes the rotor turn. Notably, the requirement for the 3-phase supply is to create this rotational magnetic flux, which is not possible with a single-phase supply.
Magnetic Induction in Safety Features and Other Applications
Magnetic induction is also used in modern safety features and various applications such as induction cooktops, electric generators, hybrid/electric vehicles and medical procedures like transcranial magnetic stimulation. In electrical generators, a coil rotates in a magnetic field to induce an alternating current emf.