What is the approximate speed of a single-phase induction motor?

The approximate speed of a single-phase induction motor is typically around 3600 RPM or lower. Single-phase induction motors operate at a speed that is determined by the synchronous speed of the motor, which is calculated based on the frequency of the power supply and the number of poles in the motor.

For a 60 Hz supply, the synchronous speed is calculated using the formula:

Synchronous Speed (RPM) = (120 x Frequency) / Number of Poles.

For a four-pole motor, the synchronous speed would be 1800 RPM, while for a two-pole motor, it would be 3600 RPM. However, due to slip, which is the difference between synchronous speed and actual speed caused by load, the actual operating speed of single-phase induction motors is generally lower than the synchronous speed. Hence, while some configurations of single-phase motors might reach 1800 RPM or vary based on specific designs, the most standard speeds observed tend to be in the category of approximately 3600 RPM or lower.

This reasoning underlines the selection of this answer as the most appropriate, as it accurately encompasses the context of typical operational speeds for single-phase induction motors.