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Torque of induction motor is proportional to
Flux
Emf
Both of above
None of above
Flux
The torque of an induction motor is proportional to the product of the air-gap flux per pole and the rotor current. Since the rotor current itself is induced by the flux (via EMF), the torque is directly dependent on both the flux and the EMF induced in the rotor.
The torque of an induction motor is proportional to the product of the air-gap flux per pole and the rotor current. Since the rotor current itself is induced by the flux (via EMF), the torque is directly dependent on both the flux and the EMF induced in the rotor.
TeтАЛ=2╧АNsтАЛ3тАЛR2тАЛ┬░2+(sX2тАЛ)2sE2тАЛ┬░2R2тАЛтАЛ тАФ Torque equation in terms of EMF
E2тАЛ=4.44frтАЛNrтАЛ╬ж тАФ EMF induced in rotor
According to the fundamental torque equation of an AC machine, T=k╬жI2тАЛcos╧Х2тАЛ. The EMF induced in the rotor (E2тАЛ) is proportional to the air-gap flux (╬ж). By Lenz's law, the rotor current (I2тАЛ) is proportional to the induced EMF (E2тАЛ). Thus, torque is proportional to the interaction of flux and induced EMF.
The stator flux sets up a rotating magnetic field which cuts the rotor conductors.
Induced EMF in the rotor is directly proportional to the rate of change of flux (╬ж).
Torque is generated by the Lorentz force produced by the interaction of the magnetic field and current-carrying conductors.
At standstill, E2тАЛ is maximum, leading to starting torque.
High reliability due to robust rotor construction.
Self-starting capability in polyphase induction motors.
High starting current compared to full load current.
Torque is sensitive to supply voltage fluctuations (proportional to V2).
Industrial drives for pumps, fans, and compressors.
Conveyor systems and elevators.
Torque is strictly proportional to the square of the applied voltage (TтИЭV2) because both ╬ж and E2тАЛ are proportional to the applied voltage.
Option A is correct but incomplete; Option B is also correct but incomplete. Since both are factors, C is the technically encompassing answer.
C is correct тАФ Torque is proportional to both the air-gap flux and the rotor induced EMF, as the electromagnetic force arises from their mutual interaction.
Always remember that in induction motors, Torque тИЭV2. If the question asks for proportionality to supply parameters, evaluate the relationship between V, ╬ж, and E2тАЛ carefully.