Are all three-phase motors considered "induction" running motors?

Three-phase motors encompass various types, and while many are classified as induction motors, it is essential to understand the underlying principles. Induction motors operate on the principle of electromagnetic induction, where the stator's rotating magnetic field induces current in the rotor, allowing it to turn.

Most industrial and commercial three-phase motors are indeed induction motors, making option A accurate in general contexts. These motors are typically robust, efficient, and widely used due to their simplicity and reliability.

However, not all three-phase motors fall under this classification. For instance, synchronous motors, which also operate on three-phase systems, do not rely on induction for their operation. Instead, they require a rotating magnetic field and an externally supplied DC current to the rotor to maintain synchronous speed.

Therefore, while it is true that a significant proportion of three-phase motors are induction-type, it does not apply universally to all, given that there are exceptions like synchronous motors. Thus, understanding the distinction between these types of motors is crucial in electrical training and application.