Induction Motors - continued

The figure provided here illustrates another design of induction motors. In this design, the rotor does not have coiled conductor, instead it is consists of a cage-type using large conductor bars. Such a design is referred to as squirrel-cage motors. This is the most common and inexpensive of the induction motor designs.

As in the wound-rotor motors, in the squirrel cage design the stator winding provided with conductor coils, but the rotor is a cage embedded in some supporting metal, such as iron. Since the cage is made of very high conductance aluminum, the net result is a high conductance cage.

The stator magnetic field induces a voltage in the rotor (conductor cage); as a result the cage creates its own magnetic field which locks in the stator rotating field. This way the stator's rotating field drags the rotor along - creating a rotational movement.