When troubleshooting a motor controller, all indications are that a relay coil should be energized. If there was no magnetic pull, with rated voltage measured across the coil, what would be the most probable cause?

Correct Answer: Option D — coil is open

An open circuit in the operating coil prevents current flow, resulting in zero magnetic pull despite full control voltage being dropped entirely across the high resistance of the open conductor, as governed by basic circuit theory outlined in IEEE 45.