🔍 Key Concepts

• Three-phase induction motor rotation and how it depends on the phase sequence of the stator supply • Difference between changing connections on the stator (line) side versus the rotor side of a wound-rotor induction motor • How rotor currents are induced by the rotating magnetic field rather than directly supplied from the line

💭 Think About

• Ask yourself: What actually creates the rotating magnetic field that sets the direction of rotation in an induction motor? Is it the stator or the rotor? • If you swap any two leads on the rotor only, without changing the stator line connections or phase sequence, does the direction of the rotating magnetic field in the air gap change? Why or why not? • Consider how motor performance (torque, slip, speed) is mainly controlled in a wound-rotor motor. Is it more sensitive to changing phase sequence on the rotor or to the external rotor resistance values?

✅ Before You Answer

• Verify which side (stator or rotor) is connected directly to the three-phase power supply and determines the phase sequence • Confirm whether interchanging two leads on the rotor alone can reverse the direction of the rotating magnetic field in the stator • Check if any textbooks or references state that reversing direction of rotation in a three-phase induction motor is done by swapping two line (stator) leads, and compare that with what happens when only rotor leads are swapped