USCG Exam PracticeMotors and generators
A DC generator fails to build up voltage after being restarted. Which of the following is the most likely cause?
- A. The armature is rotating too fast for the field poles
- B. The commutator segments are too numerous for the armature coils
- ✓ The generator has lost its residual magnetism in the field polesCorrect
- D. The shunt field rheostat is set to minimum resistance
Why C is correct
NEETS Mod. 5 §1-3 states that self-excited generators build up voltage from residual magnetism in the field poles, and that loss of residual magnetism is a common cause of no-output faults. Residual magnetism can be restored by briefly flashing the field from a separate DC source.
Cited:NEETS Mod. 5 §1-3