Red Seal Electrician Practice
TransformersQuestion 1117 of 1506

A ferroresonant transformer can ride through a very short loss of input power. How?

  1. It stores energy in an internal resonant LC circuit.
  2. It switches to a small battery that is built into the core.
  3. It uses the energy that is stored in the connected load.
  4. It opens the secondary winding for a few milliseconds.
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Correct answer: It stores energy in an internal resonant LC circuit.

The resonant tank circuit (an inductor and a capacitor) keeps a reserve of energy that feeds the load for a short time.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 10.6: Voltage Regulation

Practice transformers

Questions last reviewed: 18 October 2026