Marine Electrical Systems USCG Question #1212 (Set 41)

The motor starts when the start button in the illustration is pushed, but stops when the button is released. What is most likely the trouble? EL-0007

USCG Exam Illustration EL-0007
USCG Examination Diagram: Illustration EL-0007
Official USCG Answer & Rule Citation

Correct Answer: Option D — an open auxiliary "M" contact

The auxiliary 'M' contact provides the seal-in circuit that maintains the coil's power after the start button is released. If this contact fails to close or is open, the control circuit loses continuity as soon as the momentary start button is released, causing the motor to stop immediately.

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