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Diagram of the squirrel-cage (showing only three laminations) The motor rotor shape is a cylinder mounted on a shaft. Internally it contains longitudinal conductive bars (usually made of aluminium or copper) set into grooves and connected at both ends by shorting rings forming a cage-like shape.
Induction motors using a squirrel-cage rotor winding may have the rotor bars skewed slightly to smooth out torque in each revolution. Standardized NEMA & IEC motor frame sizes throughout the industry result in interchangeable dimensions for shaft, foot mounting, general aspects as well as certain motor flange aspect.
A squirrel-cage rotor connected to the output shaft rotates within the stator at slightly less than the rotating field from the stator. Within the squirrel-cage rotor is a freely rotating permanent magnet rotor, which is locked in with rotating field from the stator. The effect of the inner rotor is to reenforce the field from the stator. [1]
Induction (asynchronous) motors, generators and alternators (synchronous) have an electromagnetic system consisting of a stator and rotor. There are two designs for the rotor in an induction motor: squirrel cage and wound. In generators and alternators, the rotor designs are salient pole or cylindrical.
When the motor load is increased beyond the breakdown load, the motor falls out of synchronization and the rotor no longer follows the rotating magnetic field. Since the motor cannot produce torque if it falls out of synchronization, practical synchronous motors have a partial or complete squirrel-cage damper called an amortisseur winding to ...
Induction motors may be divided into Squirrel Cage Induction Motors (SCIM) and Wound Rotor Induction Motors (WRIM). SCIMs have a heavy winding made up of solid bars, usually aluminum or copper, electrically connected by rings at the ends of the rotor. The bars and rings as a whole are much like an animal's rotating exercise cage.
Small C-frame shaded-pole squirrel-cage motor. With the poles shown, the rotor will rotate in the clockwise direction. Shading coils (copper bars) within the magnetic circuit of the field coil. The shaded-pole motor is the original type of AC single-phase electric motor, dating back to at least as early as 1890. [1]
Wound-rotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit; as the motor accelerates, the resistance can be decreased. [ 1 ] Compared to a squirrel-cage rotor , the rotor of the slip ring motor has more winding turns; the induced voltage is then higher, and the current lower, than for a ...