Motor controlsQuestion 5 of 1506

A protective current relay is fed by a current transformer. What is the typical secondary current range?

  1. 0 to 120 A AC
  2. 0 to 125 A DC
  3. 0 to 5 A AC
  4. 0 to 20 mA DC
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Correct answer: 0 to 5 A AC

CTs step the monitored current down to a 0 to 5 A AC signal for the relay.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 5.4: Protective Relays

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Questions last reviewed: 18 October 2026