Which component's windings produce the rotating magnetic field in a three-phase induction motor?

• A. Rotor Windings
• B. Stator Windings
• C. Armature Windings
• D. Field Windings

Answer: (B)

In a three-phase induction motor, the source of the rotating magnetic field is the stator windings. When three-phase AC is applied to the stator, the currents in the windings are 120 degrees apart in phase. This arrangement creates a magnetic field that builds and recedes in each stator pole in a rotating fashion, producing a magnetic field that appears to spin around the air gaps between the stator and rotor.

That rotating field is what interacts with the rotor. It induces currents in the rotor (whether in a squirrel-cage or wound-rotor design), and the interaction between these rotor currents and the rotating stator field produces torque that makes the rotor turn. The rotor windings themselves don’t generate the rotating field; they respond to it and develop motion.

Armature windings and field windings are terms more commonly associated with other machine types, such as DC machines or synchronous machines, where a separate excitation coil or a different winding arrangement is used to establish the magnetic field. In a typical induction motor, the rotating field comes from the stator windings.