(1) When a three-phase asynchronous motor is connected to a three-phase AC power supply (120 degrees electric angle difference between each phase), the three-phase stator winding flows through the three-phase symmetrical current and generates a rotating magnetic field, which rotates clockwise along the stator and rotor circle space at the synchronous speed of n0.
(2) The rotating magnetic field has relative cutting motion with the rotor conductor. According to the principle of electromagnetic induction, the rotor conductor (the rotor winding is a closed path) generates the induced electromotive force and the induced current (the direction of the induced electromotive force is determined by the right-hand rule).
(3) According to the law of electromagnetic force, under the action of induced electromotive force, the induced current in the rotor conductor will be basically the same as the direction of induced electromotive force. The current-carrying rotor conductor is subjected to electromagnetic force in the magnetic field generated by the stator (the direction of force is determined by the left-hand rule). The electromagnetic force forms an electromagnetic torque on the motor rotor shaft, which drives the motor rotor to rotate in the direction of the rotating magnetic field. When the motor shaft is loaded with mechanical load, it outputs mechanical energy outward. Because the flux of the part without short-circuit ring is ahead of that of the part with short-circuit ring, the rotating direction of the motor is the same as that of the rotating magnetic field.