Question 138Electricity & Electronics - 1st Asst/Chief

70% to pass

Refer to the simplified schematic of the Ward-Leonard drive system shown in the illustration. What statement is true concerning the acceleration of the DC winch motor from minimum to base speed at constant torque? Illustration EL-0153

Diagram for USCG Electrical Chief: Refer to the simplified schematic of the Ward-Leonard drive system shown in the...
AWith a constant DC generator field current at maximum value, the DC winch motor speed increases with DC generator armature RPM.
BWith a constant DC generator armature RPM at minimum speed, the DC winch motor speed increases with increased DC generator field current from minimum to maximum.
CWith a constant DC generator field current at minimum value, the DC winch motor speed increases with DC generator armature RPM.
DWith a constant DC generator armature RPM at rated speed, the DC winch motor speed increases with increased DC generator field current from minimum to maximum.
AI Explanation

The correct answer is D. With a constant DC generator armature RPM at rated speed, the DC winch motor speed increases with increased DC generator field current from minimum to maximum. This is because increasing the DC generator field current increases the magnetic flux in the generator, which in turn increases the voltage generated by the DC generator. This higher generator voltage then allows the DC winch motor to run at a higher speed, while maintaining constant torque. The other options are incorrect because they do not accurately describe the relationship between the DC generator parameters and the resulting DC winch motor speed under constant torque conditions.

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