MotorsQuestion 1249 of 1506

A 2-pole induction motor has a synchronous speed of 3000 rpm on a 50 Hz supply. What is the synchronous speed of a 4-pole motor on the same supply?

  1. 6000 rpm
  2. 1500 rpm
  3. 3600 rpm
  4. 1800 rpm
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Correct answer: 1500 rpm

Doubling the poles halves the synchronous speed: 3000 / 2 = 1500 rpm.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 13.7: Tesla Polyphase Induction Motors

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Questions last reviewed: 18 October 2026