Answer / shailesh tankni

it is not possible to run induction motor beyond rated
speed. and if it is run beyond the rated speed by use of
external means then it will act as induction generator.

Answer / aparna

It will still run as an IM. it will run as a generator only
if the speed exceeds the synchronous speed. rated and
synchronous speeds are different from each other.

Answer / madhusudhan

alwys rated speed of an IM means its equal to synchronous
speed only,"when an IM runs beyond synchronous speed it
acts as induction generator".

Answer / manoranjan

as induction generator >120f/p

Answer / shadab murshid

In such a case slip will be negative as motor speed will be more than synchronous speed and hence the induction motor will start working as induction generator and start supplying active power to the circuit to which it is connected.

Answer / anirban dasgupta

Rated speed is not synchronous speed. Rated speed is always a few percent less than the synchronous speed. For example if a motor has a synchronous speed of 1500 rpm, its rated speed is 1460 rpm. If it is increased beyond 1500 rpm by external means, the motor will act as an induction generator.
Rated speed : The speed of the motor at rated load.
No load speed : The speed of the motor at no load. (Very Very close to synchronous speed)
Synchronous speed : The speed with which the magnetic flux rotates.

Answer / sumityadav

Induction motor acts as generator when its speed increases than the speed of its stator rotating magnetic field. If a prime mover is connected to the shaft and the stator is connected to ac supply, when it is rotated at a speed greater than the speed of rotating magnetic field, slip becomes negative(-1 < S < 0), torque becomes negative along with the rotor current and power. Therefore motor starts supplying current or power to the supply lines where it is connected.
Credit:https://www.electrical-exam.com/3-phase-induction-motor-mcq/

Answer / moses

Under rated supplied voltage condition ;An induction motor will run beyond rated speed when unloaded but this speed will be slightly less than synchronous speed.
When motor speed reaches synchronous speed the rotor will fail to rotate.

Answer / ikrambaig

basically when the machine runs at rated speed then it acts
as induction motor but when it runs beyond its rated speed
it acts as induction generator

Answer / bhatt

It will act as induction generator and it will feed power
supply from stator.

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