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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.
[a] An induction motor's rotor can be either wound type or squirrel-cage type. Three-phase squirrel-cage induction motors are widely used as industrial drives because they are self-starting, reliable, and economical. Single-phase induction motors are used extensively for smaller loads, such as garbage disposals and stationary power tools.
However, the asynchronous motor with squirrel-cage rotor had the problem of delivering only low torque at low speeds, such as when starting up. The solution was the slip ring motor, a variation of the asynchronous motor in which the short circuit of the rotor is opened and guided to the outside via sliprings. By connecting various external ...
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]
Squirrel-cage asynchronous: The most common type of shaded-pole motor in fractional horsepower use has a squirrel-cage rotor that consists of a laminated steel cylinder with conductive copper or aluminum bars embedded lengthwise in its surface, connected at the ends. Synchronous permamagnetized uses a magnetized rotor, e.g. a permanent magnet ...
In so doing, he quickly learned that he was not going to find the solution to the problem by using a normal squirrel-cage rotor. He failed a few times, but his failures finally led to the realization that the performance characteristics he was seeking might be obtained by using permanent magnet steel for the rotor instead of the original ...
Transformer action induced current into the rotor. Brush position relative to field poles meant that starting torque was developed by rotor repulsion from the field poles. A centrifugal mechanism, when close to running speed, connected all commutator bars together to create the equivalent of a squirrel-cage rotor.
The squirrel-cage rotor asynchronous motor was invented by Mikhail Dolivo-Dobrovolsky in 1889 and they were being built industrially from 1891. A problem with asynchronous machines is that they are difficult to start. The coupling to the rotor is weak until it gets moving and the current drawn by the motor is high.