A 4-pole, 60 Hz motor has synchronous speed of?

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Prepare for the NEIEP Electrical Theory and Application (430) Exam. Study with flashcards and multiple choice questions with hints and explanations. Get ready for your exam!

Multiple Choice

A 4-pole, 60 Hz motor has synchronous speed of?

Explanation:
Synchronous speed is the speed at which the magnetic field rotates and is found from Ns = 120 f / P. With a 60 Hz supply and four poles, Ns = 120 × 60 / 4 = 1800 RPM. So the rotating magnetic field turns at 1800 revolutions per minute, and the rotor in an actual motor runs a bit slower due to slip. The other speeds would correspond to different pole counts: eight poles give 900 RPM, six poles 1200 RPM, and two poles 2400 RPM.

Synchronous speed is the speed at which the magnetic field rotates and is found from Ns = 120 f / P. With a 60 Hz supply and four poles, Ns = 120 × 60 / 4 = 1800 RPM. So the rotating magnetic field turns at 1800 revolutions per minute, and the rotor in an actual motor runs a bit slower due to slip. The other speeds would correspond to different pole counts: eight poles give 900 RPM, six poles 1200 RPM, and two poles 2400 RPM.

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