USCG Exam PracticeElectrical basics — generators, motors, and safety
What is the function of interpoles in a DC generator?
- A. They increase the total flux in the main field to raise output voltage under load
- ✓ They are wound in series with the armature to automatically counter armature reaction at any load, keeping commutation sparklessCorrect
- C. They shift the brushes mechanically to the new magnetic neutral plane as load changes
- D. They store residual magnetism to allow the generator to build voltage on startup
Why B is correct
Per NEETS Mod. 5 §1-2, interpoles are small poles added between the main poles, wound in series with the armature so their field automatically counters armature reaction at any load and keeps commutation sparkless. Because they are series-wound, their corrective effect scales with load current without manual adjustment.
Cited:NEETS Mod. 5 §1-2