starting torque is increased and current is decreased by
using external resistance in a slip ring induction motor.
How??

Answer Posted / srb

It is because as the resistance is added in rotor ckt,no doubt impedance increases due to which current decreases but the effect of improved pf predominanats the inc. impedance & hence torque inc. After some tym when motor has achieved considerable speed effect of inc impedance predominanats over improved pf & hence torque decreases.

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