On DC diesel-electric drives, how is the...

🔍 Key Concepts

• Diesel-electric propulsion: how the diesel-driven generator and the DC propulsion motor interact • Generator field excitation vs motor field excitation: which one mainly determines the DC motor’s speed in a diesel‑electric system • Basic DC motor speed formula in relation to voltage and field strength

💭 Think About

• In a DC diesel-electric drive, which component actually supplies the adjustable voltage to the propulsion motor? • For a DC motor, does speed normally depend more directly on the applied armature voltage or on the prime mover (diesel engine) RPM in this type of system? • Which part is easier and more practical to vary smoothly under load: the diesel engine speed, the motor field, or the generator field?

✅ Before You Answer

• Remember that in diesel‑electric systems the diesel engine usually runs at a relatively constant speed for best efficiency and frequency control • For a DC motor, speed is approximately proportional to applied voltage and inversely proportional to field flux—consider which control method is typically used in propulsion • Verify which control method would allow smooth, wide‑range speed adjustment without frequently changing engine RPM or reversing polarity

On DC diesel-electric drives, how is the speed of the DC propulsion motor primarily controlled?

changing the motor field excitation current

changing the generator field excitation current

changing the polarity of the generator field

changing the generator engine speed

🔍 Key Concepts

💭 Think About

✅ Before You Answer