Question 263Electricity & Electronics - 1st Asst/Chief

The correct answer is D) The synchronous propulsion motors are over-excited. When the power factor associated with the main power distribution of a diesel-electric drive ship with synchronous propulsion motors is unity, it indicates that the synchronous motors are operating at a leading power factor. This means the synchronous motors are over-excited, which allows them to compensate for the lagging power factor of other loads in the system, resulting in a unity overall power factor. The other options are incorrect because: B) The excitation status of the synchronous motor can be determined to be over-excited when the power factor is unity. C) The synchronous propulsion motors are not normally excited, as they are operating in an over-excited state to achieve unity power factor.