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An induction motor can be treated as a transformer with ________________.
short circuited secondary winding
short circuited primary winding
open circuited primary winding
open circuited secondary winding
short circuited secondary winding
An induction motor acts as a rotating transformer where the stator winding functions as the primary and the rotor winding acts as a secondary winding that is always short-circuited.
An induction motor acts as a rotating transformer where the stator winding functions as the primary and the rotor winding acts as a secondary winding that is always short-circuited.
E2тАЛ=4.44f2тАЛN2тАЛ╬жmтАЛ тАФ Induced EMF in rotor winding
s=NsтАЛNsтАЛтИТNrтАЛтАЛ тАФ Slip of the induction motor
The stator carries an alternating current producing a rotating magnetic field that induces an EMF in the rotor conductors by electromagnetic induction. Since the rotor windings are permanently short-circuited by end rings (in squirrel cage) or external resistances (in slip ring), the induced EMF causes a current to circulate through the rotor, resulting in torque production.
The stator acts as the primary winding connected to the supply.
The rotor acts as a short-circuited secondary winding.
The air gap in an induction motor makes it equivalent to a transformer with high magnetizing current.
Frequency of the rotor EMF is frтАЛ=simesfsтАЛ.
Self-starting capability
High efficiency and rugged construction
High starting current
Power factor is low at light loads
Industrial drives
Fans, pumps, and compressors
In a stationary rotor (locked rotor), it behaves exactly like a transformer with a short-circuited secondary.
Option D is incorrect because an open-circuited rotor would not produce any torque as no rotor current would flow to interact with the magnetic field.
A is correct тАФ An induction motor is essentially a transformer with a short-circuited secondary winding, allowing for the flow of rotor current required for torque production.
Remember that while a transformer is a static device, the induction motor is a dynamic transformer where secondary frequency depends on the slip s.
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