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Question B.28: A four-pole synchronous motor operating from a 60-Hz supply ...

A four-pole synchronous motor operating from a 60-Hz supply will have a synchronous speed, in rev/min, of

a. 900      b. 1,800      c. 1,200      d. 3,600      e. 4,800

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Frequency =( no. of poles/2 ) \times \mathrm{rev} / \mathrm{min} / 60)

Therefore,

60=(4 / 2) \times(\mathrm{rev} / \mathrm{min} / 60)

or rev/min =1,800. Thus, b is the answer.

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