Question 116Electricity/Electronics - 1st Asst/Chief70% to pass
On an older two-generator, two-motor DC diesel-electric drive system as shown in the illustration, what are the characteristics of the main propulsion generators? Illustration EL-0141
AI Explanation
The correct answer is B.
The generators in a two-generator, two-motor DC diesel-electric drive system are direct current (DC) generators. The output voltage of these DC generators is varied by varying the generator field strength, not the rotational speed. Additionally, the output polarity of the DC generators is reversed by reversing the generator field polarity, not the generator armature direction of rotation.
The other options are incorrect because they either describe alternating current (AC) generators instead of DC generators, or they incorrectly state that the output voltage is varied by changing the rotational speed or that the polarity is reversed by changing the armature direction of rotation.
Related Questions
#114 When a self-excited DC generator's field has lost its residual magnetism due to a prolonged idle period, it will fail to produce a voltage. Flashing the field is the procedure used to restore the residual magnetism. Using a 12 volt storage battery, how is this performed? #115 On a modern silicon controlled rectified diesel-electric drive system, what are the characteristics of the main propulsion generators? #117 How is speed control of a DC propulsion motor accomplished? #118 On DC diesel-electric drives, how is the speed of the DC propulsion motor primarily controlled? #119 In a diesel-electric plant, raising the generator's field excitation current will have what effect on the DC propulsion motor speed?