Red Seal Electrician Practice
MotorsQuestion 1290 of 1506

A three-phase motor is run on a single-phase supply. What output can it give compared with its three-phase rating?

  1. The full rating
  2. 1/3 of the rating
  3. 2/3 of the rating
  4. 1/2 of the rating
Show answer

Correct answer: 2/3 of the rating

One winding is unused. A 7.5 kW motor would give 5 kW.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 13.9: Single-phase Induction Motors

Practice motors

Questions last reviewed: 18 October 2026