A three phase power supply provides a rotating ___________ field in an induction motor.

A three phase power supply provides a rotating ___________ field in an induction motor.

• A. Electric
• B. Rotating
• C. Magnetic
• D. Field

Answer: (C)

A three-phase excitation creates a rotating magnetic field in the stator. When the three windings are fed with AC voltages that are 120 degrees apart, their individual magnetic fields add up to a single magnetic field that continuously changes orientation and magnitude, effectively rotating in the air gap. This rotating magnetic field then induces currents in the rotor conductors, and the interaction between those rotor currents and the rotating field produces torque, making the rotor turn. So the essential quantity involved here is the magnetic field, and it is the rotating nature of that magnetic field that drives the motor.

A three-phase excitation creates a rotating magnetic field in the stator. When the three windings are fed with AC voltages that are 120 degrees apart, their individual magnetic fields add up to a single magnetic field that continuously changes orientation and magnitude, effectively rotating in the air gap. This rotating magnetic field then induces currents in the rotor conductors, and the interaction between those rotor currents and the rotating field produces torque, making the rotor turn. So the essential quantity involved here is the magnetic field, and it is the rotating nature of that magnetic field that drives the motor.