Question 1Electricity & Electronics - 1st Asst/Chief

70% to pass

As shown in the illustrated electric propulsion control scheme for a twin screw vessel, when the two shaft speeds are within 5% of each other, the bridge may select "shaft synchro- phasing mode". What statement is true regarding the purpose of this operating mode? Illustration EL-0168

Diagram for USCG Electrical Chief: As shown in the illustrated electric propulsion control scheme for a twin screw...

AVibration sensors are used to achieve identical shaft speeds and propeller synchronization to minimize vibration.

BThe respective shaft speed sensors alone are used to achieve identical shaft speeds without regard to propeller position to achieve even power development.

CThe respective shaft speed and shaft position sensors are used to achieve identical shaft speeds and propeller synchronization to minimize shaft vibration.

DCavitation sensors are used to achieve identical shaft speeds and propeller synchronization to minimize vibration.

AI Explanation

The correct answer is C. The purpose of the "shaft synchro-phasing mode" is to achieve identical shaft speeds and propeller synchronization in order to minimize shaft vibration. This is accomplished by using both the respective shaft speed and shaft position sensors to ensure the propellers are rotating in sync. The other options are incorrect because: A) Vibration sensors are not used for this purpose. B) Achieving identical shaft speeds alone is not enough to minimize vibration without also synchronizing the propeller positions. D) Cavitation sensors are not involved in this process.

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