🔍 Key Concepts

• Generator field excitation vs terminal voltage in an AC synchronous generator feeding a rectifier • Effect of DC armature voltage on the speed of a DC propulsion motor at a given load • Difference between DC motor behavior and AC power factor concepts

💭 Think About

• If you raise the field excitation of the AC generator, what normally happens to the generator’s output voltage when the speed and load are held roughly constant? • After rectification, if the DC supply voltage to the propulsion motor changes, how does that affect the speed of a DC motor whose field is unchanged and load is similar? • Look at the answer choices: which ones talk about motor speed, and which ones talk about an AC characteristic that doesn’t really belong to a DC propulsion motor’s operation?

✅ Before You Answer

• Confirm that increased field excitation on a synchronous generator (at constant speed) tends to raise terminal voltage for a given load • Confirm that for a DC motor, at essentially constant field flux, speed is roughly proportional to applied armature voltage • Verify that power factor is an AC-side concept, while the propulsion motor in the question is DC, fed from a rectified source