🔍 Key Concepts

• Ward-Leonard drive speed control: armature voltage control vs field control • Relationship for a DC motor: speed is roughly proportional to armature voltage / field flux • Above base speed, keeping horsepower constant means torque goes down as speed goes up

💭 Think About

• From minimum to base speed, which control (armature voltage or field current) is mainly used, according to the lower graph in the illustration? • From base speed to maximum speed at constant power, what happens to armature voltage and what happens to field current, as shown in the shaded "Field Control" region? • Looking at each answer choice, which one correctly describes generator field and motor field conditions that match the constant-power, field-weakening region?

✅ Before You Answer

• Verify in the lower diagram that armature voltage is at maximum once base speed is reached and remains so in the constant-power region. • Check that in the constant-power region, the motor field current is changing (field weakening) while generator speed stays constant. • Make sure the option you pick shows generator field set for maximum armature voltage during the constant-horsepower acceleration from base to maximum speed.