Question

Regenerative braking occurs only when the motor speed \(N\)

• A. Is less than the synchronous speed
• B. Is greater than the synchronous speed
• C. Is exactly equal to synchronous speed
• D. Is zero

Hint:

Regenerative braking of an induction motor occurs when rotor speed is greater than synchronous speed.

Answer 1

The Correct Option is B

Concept: Regenerative braking in an induction motor occurs when the motor acts as a generator and returns power to the supply.

Step 1: In normal motoring operation: \[ N<N_s \]

Step 2: If the rotor speed becomes greater than synchronous speed: \[ N>N_s \] then slip becomes negative.

Step 3: Negative slip means the machine operates as an induction generator.

Step 4: In this condition, power is fed back to the supply, producing regenerative braking. Therefore: \[ \boxed{\text{Is greater than the synchronous speed}} \]