The torque developed by a 3-phase induction motor least depends on which the following options?

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SSC JE Electrical 05 Jun 2024 Shift 3 Official Paper - 1
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  1. rotor EMF
  2. rotor current
  3. shaft diameter
  4. rotor power factor

Answer (Detailed Solution Below)

Option 3 : shaft diameter
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Torque Development in a 3-Phase Induction Motor:

The torque developed by a 3-phase induction motor depends on several factors related to the rotor and stator. The key factors influencing the torque are:

  • Rotor EMF: The induced electromotive force in the rotor windings.
  • Rotor Current: The current flowing through the rotor windings.
  • Rotor Power Factor: The phase angle between the rotor current and the rotor EMF.
     

These factors are crucial in determining the electromagnetic torque generated by the motor. The electromagnetic torque (T) can be expressed as:

T ∝ (Er Ir cos(ϕr))

Where:

  • Er = Rotor EMF
  • Ir = Rotor current
  • cos(ϕr) = Rotor power factor
     

The shaft diameter primarily affects the mechanical strength and the ability of the motor to handle mechanical loads, but it does not directly influence the electromagnetic torque developed by the motor.

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