Refer to the diagram of the AC turboelectric drive system as shown in the illustration. The propulsion motor operates from maneuvering speed to full ahead speed in the ahead direction. The propulsion motor will not operate at any speed in the astern direction. What is most likely the problem? Illustration EL-0142

Correct Answer: Option A — The reversing contactor (R) fails to pull in.

In an AC turboelectric drive system, reversing propulsion rotation requires reversing the phase sequence or field polarity. When the motor operates ahead but fails in astern, the primary reversing contactor (R) has typically failed mechanically or electrically to pull in.