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Maximum (Pullout)
Torque in an Induction
Motor
Estamo, Patrick Carmel
Ruiz, Francis Emil
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Maximum Pullout Torque
• It occurs when the air-gap power is
maximum, where the air-gap power
is equal to the power being
consumed by the resistor 𝑅2 /𝑠
• The maximum induced torque will
occur when the power consumed by
that resistor is maximum.
2 2
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Maximum Pullout Torque
The maximum Power
occurs when:
3 3
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title style
Maximum
Pullout
Torque
• The maximum torque is proportional to
the square of the supply voltage.
• The maximum torque is inversely
proportional to the stator impedance
and rotor reactance.
• The smaller a machine’s reactance's,
the larger the maximum torque.
• Slip at which the maximum torque
occurs is directly proportional to rotor
resistance.
4 4
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Maximum Pullout Toque
• Inserting resistance into the rotor
circuit > Increase the slip > The speed
decreases > Maximum Pull-out torque
remains constant.
• For heavy load: Increase rotor
resistance > Maximum torque at lower
speed > Once the load turning remove
the resistance > Maximum torque at
near synchronous speed.
5 5
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Thank You
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