NapkinCalc

AC Motors

Synchronous speed

The field rotates at n_sync = 120·f / p, where p is the number of magnetic poles. More poles = slower field. At 60 Hz: 2 poles → 3600 rpm, 4 → 1800, 6 → 1200.

fline=60f_{line} = 60 line frequency (Hz)
ppoles=4p_{poles} = 4 number of poles
nsync=120⋅flineppolesn_{sync} = \frac{120 \cdot f_{line}}{p_{poles}} = 18001800 synchronous speed (rpm)