We have seen that the reduced voltage can be applied to the stator by adding the rheostats in the stator circuit. The arrangement is shown in the Fig. 1. The part of the voltage gets dropped across the resistances and reduced voltage gets applied across the stator.
The reduction in stator voltage causes reduction in the speed. The rheostats can be varied as per the required change in speed. But the entire line current flows through the rheostats and hence there are large power losses. The method is not efficient from speed control point of view hence used as a starter rather than as a speed control method.
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| Fig. 1 Stator resistance control |
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