Facts At Your Fingertips: Alternating-Current Induction Motors

Alternating-current (a.c.) induction motors are widely used throughout the chemical process industries (CPI) and other manufacturing sectors to convert electrical energy into mechanical energy to power rotating equipment, such as centrifugal pumps, compressors and fans, as well as other industrial machinery. This one-page reference provides information on the construction and operation of three-phase induction motors (Figure 1). FIGURE 1. In this cutaway image of the interior of an electrical induction motor, the rotor can be seen inside the stator, which surrounds it[/caption] Motor components The basic construction of a typical industrial a.c. induction motor includes the following elements: rotor, stator, stator windings and enclosure. Rotor. The rotor has an iron core made from a cylinder-shaped stack of laminated rings around a motor shaft to which it is attached. The rotor has conducting end caps on either end and conducting bars that run through slots in the laminated metal stack between the end caps. The assembly rotates inside the stator on bearings, which ensure that the rotor remains centrally positioned with the stator. The appearance of the rotor and conducting bars gives rise to the name “squirrel-cage motor.” …