What is the formula for calculating the synchronous speed of a rotating magnetic field around the stator?

The formula for calculating the synchronous speed of a rotating magnetic field around the stator is represented as N = 120f/P, where N is the synchronous speed in revolutions per minute (RPM), f is the frequency of the AC supply in hertz (Hz), and P is the number of poles in the stator.

This equation is derived from the principles of electromagnetic induction and the relationship between frequency and the physical rotation of the stator. The factor of 120 comes from the need to convert the frequency (which is measured in hertz or cycles per second) into a speed (measured in revolutions per minute). The number of poles affects how many times the magnetic field rotates per cycle of the alternating current. Thus, a higher number of poles would yield a lower synchronous speed at a given frequency, and conversely, fewer poles would allow for a higher synchronous speed.

The structure of the formula clearly indicates that as the frequency increases, the synchronous speed also rises, while increasing the number of poles decreases the speed. This understanding is critical for designing and analyzing synchronous motors and generators, ensuring they operate efficiently at their designated specifications.