🔍 Key Concepts

• Ward-Leonard speed control: armature voltage control from minimum to base speed, then motor field weakening for speeds above base speed • How generator field and motor field circuits each affect the DC motor’s armature voltage and speed • What happens to speed if the field cannot be weakened versus if the field or supply is completely open or dead

💭 Think About

• From the graph, what changes between minimum and base speed, and what changes between base speed and maximum speed? Which control (armature or field) is responsible for each region? • If the system works perfectly up to base speed, which part of the Ward-Leonard system must already be functioning correctly? Which fault options would prevent it from ever reaching normal base speed? • For each answer choice, ask: would this fault (a) let the motor run normally up to base speed, but (b) block any further speed increase above base speed without completely stopping the system?

✅ Before You Answer

• Identify which component is used for armature voltage control (region labeled ‘Armature Control’ in the graph) and which is used for field control (region labeled ‘Field Control’). • For each choice, verify whether the fault would still allow rated armature voltage and normal base-speed operation. • Focus on the option that would hold the motor field at maximum strength so the field current cannot decrease as shown by the ‘Decreasing Field Current’ curve.