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A center ammeter connected to the rotor end circuit of a 6-pole,50 Hz, induction motor makes 45 complete oscillations in a minute. Then the rotor speed and the speed of stator field w.r.t. rotor is?

A center ammeter connected to the rotor end circuit of a 6-pole,50 Hz, induction motor makes 45 complete oscillations in a minute. Then the rotor speed and the speed of stator field w.r.t. rotor is? Correct Answer 985, 15

Rotor frequency = s*f1 = 45/60 = 0.75 Hz. s = 0.75/50 = 0.015 rotor speed = 1000(1-0.015) = 985 rpm. Speed of stator field w.r.t. rotor = Ns-Nr = 1000-985=15 rpm.

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