Question 60Electricity/Electronics - 1st Asst/Chief70% to pass
Refer to the two-generator, two-motor, DC diesel-electric drive propulsion system simplified schematic shown in the illustration. Which of the following conditions would cause the propulsion shaft to only rotate in the ahead direction? Illustration EL-0141
AI Explanation
The correct answer is C) A failure of the controlled rectifier to reverse polarity to the generator field windings.
In a DC diesel-electric drive propulsion system, the controlled rectifier is responsible for reversing the polarity of the generator field windings, which in turn reverses the direction of the generator output and ultimately the direction of the propulsion shaft. If the controlled rectifier fails to reverse the polarity, the generator output will remain in the same direction, preventing the propulsion shaft from rotating in the reverse direction.
The other options are incorrect because they do not directly impact the ability to reverse the direction of the propulsion shaft. A failure of the main propulsion diesel generators engines (A) or the field rheostats (B) would not prevent the controlled rectifier from reversing the polarity, and a failure of the non-controlled rectifier (D) would not affect the generator field windings.
Related Questions
#58 The conversion of constant frequency power into adjustable frequency power in a modern AC propulsion drive system is commonly achieved through the use of what electronic system components? #59 As shown in the illustration of a DC diesel-electric propulsion drive system, what would be the set up contactor configurations if #1 M/E is to be secured, so that only #2 M/E diesel-generator is set up to supply both propulsion motors? Illustration EL-0141 #61 While standing an "at sea watch" onboard a modern rectified DC diesel-electric drive ship you notice the transformer core temperature slowly rising. What should be your FIRST action? #62 Refer to the two-generator, two-motor, DC diesel-electric drive propulsion system simplified schematic shown in the illustration. While in two-generator, two-motor operation, which of the following conditions would cause the propulsion shaft speed to be approximately one-half the desired speed? Illustration EL-0141 #63 If the values of ‘C1’ and ‘R1’ shown in the illustration were 1 microfarad and 3 megohms respectively, which of the listed intervals of time would equal one 'time constant'? Illustration EL-0086