Question 206Electricity & Electronics - QMED

The correct answer is D) application of a three-phase voltage supply to the stator windings. In a three-phase, squirrel-cage type, induction motor, the primary rotating magnetic field is established by applying a three-phase voltage supply to the stator windings. This creates a rotating magnetic field in the stator, which then induces a current in the rotor's squirrel-cage bars. The interaction between the stator's magnetic field and the induced current in the rotor's squirrel-cage bars produces the torque that causes the rotor to rotate. The other answer choices are incorrect because they do not accurately describe how the primary rotating magnetic field is established in this type of induction motor. Option A refers to the construction of the rotor, not the establishment of the magnetic field. Option B describes the induced current in the rotor windings, which is a result of the rotating magnetic field, not the cause of it. Option C describes the interaction between the magnetic fields, but does not explain how the primary rotating magnetic field is initially established.