Motor controlsQuestion 92 of 1506

A furnace must run its air fan for a set time before it can be lit. Which device supplies this time element?

  1. A time-delay relay
  2. A pressure switch
  3. A mercury switch
  4. A snubber
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Correct answer: A time-delay relay

This purge clears flammable or explosive vapours.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 5.3: Time-delay Relays

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Questions last reviewed: 18 October 2026