Motor controlsQuestion 34 of 1506

In a PLC start-stop program, what is used as the seal-in?

  1. A second physical push button wired in parallel with the start button
  2. A program contact of the output coil, in parallel with the start contact
  3. A hardware timer connected to the input terminal of the PLC
  4. A fuse wired in series with the output of the PLC to the coil
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Correct answer: A program contact of the output coil, in parallel with the start contact

The output status contact (Y1) keeps the coil on after the start input drops.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 6.6: Programmable Logic Controllers (PLC)

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Questions last reviewed: 18 October 2026