Number of Pole Pairs

The number of pole pairs determines the synchronous speed of the three phase motor.

nsync = synchronous speed
f = frequency of the 3-phase power supply
p = number of pole pairs of the 3-phase motor

Kindly note that the above noted relation results in revs per second if the frequency unit is Hz.

Pole pair numbers 1 2 3 4 5 6
Synchronous speed (at 50 Hz) n [rpm] 3000 1500 1000 750 600 500
Synchronous speed (at 60 Hz) n [rpm] 3600 1800 1200 900 720 600

The rated full-load speed of three phase asynchronous motors is, due to slip, a few percent below the synchronous speed.

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