What would be the synchronous speed of a 24-pole three-phase synchronous motor operating at 20 Hz?

Correct Answer: Option B — 100 rpm

Synchronous motor speed depends on frequency and pole count via $N_s = (120 \times f) / P$. With a frequency of 20 Hz and 24 poles, $(120 \times 20) / 24 = 100\text{ rpm}$. Compliance with IEEE 45 ensures accurate matching of motor performance to specialized low-frequency drives.