Number of Pole Pairs

nsync = synchronous speed f = frequency of the 3-phase power supply p = number of pole pairs of the 3-phase motorKindly note that the above noted relation results in revs per second if the frequency unit is Hz.
Pole pair numbers123456
Synchronous speed (at 50 Hz) n [rpm]300015001000750600500
Synchronous speed (at 60 Hz) n [rpm]360018001200900720600
The rated full-load speed of three phase asynchronous motors is, due to slip, a few percent below the synchronous speed.