USCG Exam PracticeAC circuits and theory
The output frequency of a shipboard alternator is determined by which two factors?
- A. Field current and stator winding resistance
- ✓ Rotor speed (rpm) and number of polesCorrect
- C. Supply voltage and load impedance
- D. Exciter output voltage and armature reactance
Why B is correct
NEETS Mod. 5 §3-1 gives the formula f = (poles × rpm) / 120. A 60 Hz, 4-pole machine must turn at exactly 1800 rpm. Field current controls output voltage through the voltage regulator, not frequency. Load impedance and exciter voltage do not appear in the frequency equation.
Cited:NEETS Mod. 5 §3-1