The squirrel cage induction motor has its winding composed of bars that are welded at their ends by a short circuit ring. These bars can be of various shapes with variations in the dimensions and section of the bar profile. This range of combinations makes possible a wide control of the motor’s electrical parameters, such as the maximum conjugate, starting conjugate, efficiency, power factor, starting current, among others.

This winding behaves like the secondary of a shorted transformer, operating with high current intensities, especially at start-up.

Normally the problems that occur in these windings are related to cracks or rupture of these bars due to the high efforts required. Electromagnetic forces, high currents, thermal expansions and centrifugal forces are the main components that help to “stress” and generate failures. When this winding presents a problem, the motor loses torque and conjugate and there is also a decrease in the power factor and the motor starts consuming more reactive power.

It is worth remembering that in smaller motors, the cage winding is usually made of injected aluminum, and damage to this winding makes it difficult to repair.
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