Induction AC Motors

  Earlier we introduced the concept that all Electric Motors shared the common underlying principle which converts electrical energy to magnetic energy to rotating mechanical energy. We also introduced the concept of a rotor and stator and the rotating field which results in rotational movement. The different types of motors result from the various clever ways in which the rotor and stators are constructed and the manner in which the rotating field (which is essential to rotating movement) is generated.

  In an induction motor, the rotor is the inner part and the stator is the external part. The AC electrical current is fed into the stator. As the sine wave of the AC electrical current goes up and down, it creates a rotating field. The rotor consists of a series of bars which are welded together at either end. The current is “induced” in the rotor from the electrical field in the stator. This current circulates in the bars of the rotor and the magnetic field generated by it reacts with the stators field. As the magnetic field in the stator rotates, the rotor follows and rotating force (torque) is generated.