Michelin ECT GAP Practice Test

The correct answer is that the rotor speed in a synchronous motor is equal to the speed of the rotating magnetic field. In a synchronous motor, the rotor is designed to rotate at the same speed as the stator's rotating magnetic field. This occurs because the rotor is magnetically locked to the rotating field, allowing it to synchronize its rotation with the field produced by the stator.

This synchronization is a key characteristic of synchronous motors, distinguishing them from other types such as induction motors, where the rotor speed is typically less than the speed of the rotating magnetic field. For synchronous motors, the rotor magnetic field is maintained in alignment with the stator's magnetic field, leading to efficient energy conversion.

The essential feature of this relationship ensures that the motor can operate effectively at a specific synchronous speed determined by the supply frequency and the number of poles in the motor design. Understanding this relationship is crucial for the proper application and performance assessment of synchronous motors in various industrial contexts.