🔍 Key Concepts

• Synchronous motor rotor behavior at steady speed • Difference between induction (asynchronous) and synchronous motor torque production • Role of excitation current and damper (amortisseur) windings

💭 Think About

• Ask yourself: when the rotor is running at exactly synchronous speed, is there any slip to induce rotor current like in an induction motor? So how is torque produced? • What is the purpose of amortisseur (damper) windings during start-up versus during normal synchronous running? • How does DC excitation in the rotor interact with the rotating magnetic field of the stator at synchronous speed?

✅ Before You Answer

• Verify which option actually explains how continuous torque is produced once the rotor is at synchronous speed, not how it is started. • Check whether slip exists in a perfectly synchronous motor under steady operation and whether torque can depend on slip in that condition. • Identify the function of amortisseur (damper) windings: are they the main cause of synchronous running, or mainly for starting and damping oscillations?