What is the term for when a synchronous motor changes from induction to synchronous operation?

The term that describes the phenomenon when a synchronous motor changes from induction to synchronous operation is known as the "pull-in point." This is the specific moment during motor operation when the rotor synchronizes with the rotating magnetic field created by the stator.

Understanding the pull-in point is crucial because it signifies the transition where the rotor becomes locked in with the stator's magnetic field, enabling the motor to operate efficiently at synchronous speed. At speeds below synchronous speed, the motor initially operates as an induction motor, relying on slip to produce torque. Once the motor reaches the pull-in point, it can maintain synchronous speed without resorting to slip, allowing for more stable and efficient operation.

Recognizing the pull-in point helps in the design and operation of synchronous motors, especially in applications where precise speed control and efficiency are paramount.