When the induction motor working as induction generator?

Answer 1

An induction motor connected to an existing ac supply normally runs at less than the synchronous speed by an amount described as the 'slip' which is proportional to the torque demanded at the shaft.

If the same motor is instead coupled to an engine and driven at a speed higher than the synchronous speed, with negative slip, power then travels back into the ac supply and the motor has become a generator. The amount of power produced depends on the speed.

However a normal induction motor will not behave as a stand-alone ac generator.

For ac power generation synchronous generators are invariably used because it is necessary to set and maintain the frequency of the supply accurately.

Answer 2

Contrary to DC and synchronous motors, it's a bit tricky to turn an Induction Motor into a generator.

You need to connect charged capacitors to the stator (either in Y or Delta coupling) in order to provide magnetic excitation

and you must turn the rotor ABOVE the rated synchronous speed of the motor.

Answer 3

The Synchronous motor becomes a Synchronous generator when the speed of rotor increase from the rotating magnetic field of the stator.

Answer 4

No a 220 volt induction motor will not produce 220 volts when used as a generator.