How Does a Three-Phase Motor Create Rotation? A...

How Does a Three-Phase Motor Create Rotation? A three-phase induction motor receives three alternating currents—Phase A, Phase B, and Phase C. These currents reach their maximum values at different times, separated by exactly 120 electrical degrees. Each current flows through a separate stator winding and produces its own magnetic field. Because the three magnetic fields rise and fall at different moments, they combine to form one magnetic field that continuously rotates around the stator. Think of three people pushing a circular wheel one after another. Each push happens at the correct moment, so the wheel experiences a smooth, continuous force instead of separate jerks. This rotating magnetic field cuts through the rotor conductors and induces current inside them, according to Faraday’s law. The induced rotor current creates another magnetic field. The stator’s rotating field pulls the rotor’s magnetic field along with it, producing torque and making the rotor spin. However, the rotor must always rotate slightly slower than the magnetic field. This speed difference is called slip. Without slip, no current would be induced—and the motor would produce no torque.