What primarily determines the speed of a single-phase motor?

The speed of a single-phase motor is primarily determined by the number of stator poles. This is a fundamental characteristic of electric motors, tied to the synchronous speed, which is calculated based on the number of poles in the stator windings and the frequency of the electric supply.

For a single-phase motor, the synchronous speed (in RPM) can be calculated with the formula:

[ \text{Synchronous Speed} (N_s) = \frac{120 \times \text{Frequency (Hz)}}{\text{Number of Poles}} ]

This means that as the number of poles increases, the synchronous speed decreases, assuming the supply frequency remains constant. Therefore, the design of the motor, specifically how many poles it has, plays a crucial role in determining the theoretical maximum speed at which it can operate.

While factors like applied voltage, load, and winding configuration can influence the performance and efficiency of the motor, they do not fundamentally change the speed at which it operates under ideal conditions. The load can affect the actual running speed, as under heavy load conditions, the motor may slow down, but this is a result of load dynamics and not a change in the motor's inherent design characteristics. Thus, understanding the importance of the