🔍 Key Concepts

• Induction motor slip and how it relates to rotor speed vs. synchronous speed • How a wound-rotor induction motor differs from a squirrel-cage motor in terms of external rotor circuit access • Effect of adding resistance in the rotor circuit on torque and speed

💭 Think About

• Think about whether an induction motor’s rotor ever truly reaches synchronous speed under normal operation and why. • Ask yourself: what does having slip (difference between synchronous speed and rotor speed) allow you to control in a wound-rotor motor? • Consider which type of control device can practically change rotor circuit resistance while the motor is running.

✅ Before You Answer

• Verify whether speed in an induction motor is strictly fixed by the number of poles, or if that applies more directly to synchronous speed of the rotating magnetic field. • Check if rotor speed = synchronous speed can occur under load for an induction motor, or if there is always some slip. • Confirm which method (if any) uses a rheostat in the rotor circuit of a wound-rotor induction motor to adjust speed.