If a 12-pole three-phase synchronous alternator is operating at 590 rpm, what will be its output frequency?

Correct Answer: Option B — 59 Hz

Alternator frequency is determined by $f = (P \times N) / 120$. For a 12-pole machine running at 590 rpm, $(120 \times 59) / 120$ yields 59 Hz. 46 CFR Subchapter J and IEEE 45 regulate generator synchronization and frequency stability under varying shipboard load conditions.