The synchronous speed of a motor is defined as:

The synchronous speed of a motor refers to the speed at which the magnetic field rotates within the stator, and it is determined by the frequency of the electrical supply and the number of poles in the motor. This speed is calculated using the formula:

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

This means that synchronous speed is essentially the maximum speed a motor can achieve under ideal conditions, without any load or slip. The rotor will attempt to catch up to this speed when the motor is started, but it cannot actually reach this speed in practical scenarios due to slip, which occurs when the rotor lags behind the rotating magnetic field created by the stator.

Understanding this concept emphasizes that synchronous speed is inherently linked to the motor's design and electrical characteristics, rather than operational factors like load or low speeds. This distinguishes it from other speeds, such as those achieved under load, while operating, or at reduced capacity, which are not reflective of synchronous speed itself.