A 3-phase synchronous motor originally has 4 poles and operates at 50 Hz. If the frequency, number of poles, and load torque are all reduced to half their initial values, what will be the new motor speed?

Synchronous Motors MCQs for PPSC, FPSC, NTS, and Pakistan government job tests. Select an option below, then read the explanation.

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Subject
Synchronous Motorselectrical-engineering-mcqs › synchronous-motors
Published
19 Oct 2018
Last updated
28 May 2026

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Explanation

The synchronous speed of a motor is given by the formula: N = (120 × f) / P, where N is speed in rpm, f is frequency in Hz, and P is the number of poles. Halving both frequency and poles keeps the speed the same as before, which is 1500 rpm. Load torque does not affect synchronous speed.

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