🔍 Key Concepts

• Armature voltage control vs. field (flux) control regions shown in figure "B" • How DC motor speed is affected by changes in armature voltage at constant field current • How DC motor speed is affected by weakening (reducing) the field current at maximum armature voltage

💭 Think About

• Look at the far left side of the speed axis (minimum speed). Is the motor in the armature control region or the field control region? • In that region, according to the diagram, what is happening to armature voltage as speed changes, and what is happening to field current (constant, increasing, or decreasing)? • For a DC motor starting from very low speed, do we usually keep the field strong or weak, and why with respect to torque and control?

✅ Before You Answer

• Verify on figure "B" that at minimum speed the motor is still under armature control, not field control • Confirm from the graph that during armature control, the field current is at maximum (constant) value • Confirm from the slanted line that armature voltage is lowest at minimum speed and increases toward base speed