The two factors used to determine the speed of ac motors are the frequency of the power supply and the number of poles in the motor winding.
Explanation:
The frequency of the power supply and the number of poles of the machine states the synchronous speed.
The poles combined with ac line frequency determines the no-load revolutions per minute of the monitor. So all four-pole motors will run at same speed under no-load conditions, then all six-pole motors will run at the same speed.
The speed of the induction motor depends on stator frequency "s ". By varying the stator voltage and constant supply frequency the speed can be controlled. The two main components of the electric motor are stator and rotor.