Q8Basic Electrical Engineering
Question
Q.8. Distinguish between induction motor and synchronous motor.
Answer
Induction motors operate asynchronously relying on induced rotor currents, whereas synchronous motors operate strictly at synchronous speed utilizing DC rotor excitation.
1. Operating Speed: An induction motor always runs at a speed slightly less than the synchronous speed (due to slip), making it an asynchronous machine. A synchronous motor strictly runs at exactly the synchronous speed (), regardless of mechanical load variations, until it is overloaded and falls out of step.
2. Excitation and Starting: Induction motors are singly-excited (AC supply only to stator) and are inherently self-starting. Synchronous motors are doubly-excited (AC to stator, DC to rotor) and are NOT inherently self-starting; they require a prime mover or damper windings to reach synchronous speed.