Red Seal Electrician Practice
MotorsQuestion 1255 of 1506

A squirrel cage motor draws about 500% of full load current at start. What is the reason?

  1. The stator winding is open for the first moments of the start.
  2. A stopped rotor acts like a shorted transformer secondary.
  3. The power factor is unity while the rotor is stopped.
  4. The rotor is feeding a voltage back into the line.
Show answer

Correct answer: A stopped rotor acts like a shorted transformer secondary.

A locked rotor is a shorted secondary, so the primary draws a high current.

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

Practice motors

Questions last reviewed: 18 October 2026