How does electric supply frequency affect an induction motor’s synchronous speed?

The synchronous speed of an induction motor is directly proportional to the frequency of the electric supply. In an induction motor, the stator windings produce a rotating magnetic field that revolves at a specific rate known as the synchronous speed.1

This speed is determined by the formula:
$$\text{Synchronous Speed (rpm)}=\frac{120f}{p}$$

In this equation:
* f represents the frequency of the electric supply in hertz (cycles per second).12
* p represents the number of magnetic poles in the motor.1

Because the synchronous speed is calculated as $120f/p$, an increase in the supply frequency ($f$) results in a proportional increase in the synchronous speed, while a decrease in frequency results in a lower synchronous speed. While induction motors are often operated on constant-frequency utility supplies, they can be used for precise speed control by utilizing an electronic inverter to adjust the frequency of the power supplied to the stator windings.12