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Question 396

What is the purpose of a step-start circuit in a high-voltage power supply?

  1. To provide a dual-voltage output for reduced power applications
  2. To compensate for variations of the incoming line voltage
  3. To prevent arcing across the input power switch or relay contacts
  4. To allow the filter capacitors to charge graduallyCorrect answer

Explanation

Uncharged filter capacitors look like a short circuit at the instant power is applied. A step-start circuit inserts a resistance in series for a fraction of a second and then shorts it out, letting the capacitors charge gradually and limiting the inrush surge.

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Question 396: What is the purpose of a step-start circuit in a… · FCC Amateur Extra Class (Element 4) · Questena