🔍 Key Concepts

• Relationship between brush position and the magnetic neutral plane in a DC generator • How positive and negative brushes must alternate around the commutator to avoid short circuits and balance load • Effect of unequal spacing or grouping of like‑polarity brushes on commutator sparking and current sharing

💭 Think About

• Look at how the + and − brushes are arranged around the commutator in each figure. In a properly configured generator, should like polarities be grouped together or evenly distributed? • Consider current leaving and returning to the armature: how must the brushes be positioned so that each path through the armature carries approximately the same current? • Which figure best represents brushes placed along the neutral plane, with + and − brushes alternating so no two adjacent segments are shorted by brushes of opposite polarity?

✅ Before You Answer

• Verify that positive and negative brushes alternate around the commutator rather than being bunched on one side • Check that brushes of the same polarity are equally spaced so each armature path shares the load • Confirm that the configuration you choose would minimize sparking and avoid any path that directly shorts + to − across adjacent commutator segments