AC motors that use stators are called?

• A. Induction (or stator-based) motors
• B. Synchronous motors
• C. DC motors
• D. Universal motors

Answer: (A)

AC motors that rely on the stator are the induction motors. The stator windings produce a rotating magnetic field when fed with AC. In an induction motor, the rotor isn’t connected to the power supply; instead, the changing field induces currents in the rotor. These rotor currents interact with the stator field to produce torque, and the rotor spins at a speed slightly below the rotating field—this difference is called slip.

This is what sets induction motors apart from other AC machines. Synchronous motors also use a stator to create a rotating field, but their rotor is magnetized or DC-excited and locks to the stator field, turning at the same speed as the supply frequency with no slip. DC motors run on direct current with a commutator and are not AC stator-based machines. Universal motors can run on AC or DC and are typically series-wound with a commutator, not relying on inducing rotor currents in the way induction motors do.