Red Seal Electrician Practice
MotorsQuestion 1027 of 1506

What is the most important benefit of polyphase power for motors?

  1. A higher shaft speed than any single-phase supply
  2. No need for windings in the stator
  3. A rotating magnetic field with a set direction
  4. Zero current in the stator at all times
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Correct answer: A rotating magnetic field with a set direction

Three phases create a field that turns, which pulls the rotor around. Tesla used this idea for the first polyphase systems.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 7.4: Polyphase Motor Design

Practice motors

Questions last reviewed: 18 October 2026