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For a three phase induction motor, maximum torque is double the full load torque and starting torque is 1.6 times the full load torque. To get a full load slip of 5%, percentage reduction in the rotor resistance should be?

For a three phase induction motor, maximum torque is double the full load torque and starting torque is 1.6 times the full load torque. To get a full load slip of 5%, percentage reduction in the rotor resistance should be? Correct Answer 62.7%

Slip at which maxim torque occurs is calculated as smT=0.5. r2/x2=0.5 for full load slip of 0.05, 1/2 = 2/((0.05/sf)+(sf/0.05)) smT2 = 0.186 reduction in resistance = (0.5×2-0.186×2)/0.5×2 = 63%.

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