Q28/ For a 3-phase slip-ring induction motor, the maximum torque is 2.5times the full-load torque and the starting torque is 1.5 times the full-load torque. Determine the percentage reduction in the rotor circuit resistance to get full-load slip at 3%.Neglect stator impedance. Ans[ 56.8%]

Q28/ For a 3-phase slip-ring induction motor, the maximum torque is 2.5times the full-load torque and the starting torque is 1.5 times the full-load torque. Determine the percentage reduction in the rotor circuit resistance to get full-load slip at 3%.Neglect stator impedance. Ans[ 56.8%]

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter35: Harmonics 916

Section: Chapter Questions

Problem 3RQ: Would a positive-rotating harmonic or a negative-rotating harmonic be more harmful to an induction...

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Concept explainers

Three Phase Induction Motor

The induction motor is an electric motor that runs on AC (alternating current) and it is of two type single phase motor that work on single-phase power supply and three-phase motor that work on three-phase power supply.

Question

Q27/ A 6-pole, wound induction motor operates from a 3-phase, 50 Hz supply. The rotor parameters
3
Tutorial Sheet (2)
are R2-D0.12/phase and X2-D0.52/phase. Calculate the speed at which maximum torque occurs
and the value of external resistance necessary in the rotor circuit from this torque to occur the
starting.
Ans[800 r.p.m., 0.42/phase]
Q28/ For a 3-phase slip-ring induction motor, the maximum torque is 2.5times the full-load torque and
the starting torque is 1.5 times the full-load torque. Determine the percentage reduction in the rotor
circuit resistance to get full-load slip at 3%.Neglect stator impedance.
Ans[ 56.8%]
Q29/ A 3-phase induction motor has a synchronous speed of 250 r.p.m. and 4% slip at full-load. The
rotor has a resistance of 0.022 per phase and standstill leakage reactance of 0.152 per phase.
Calculate (i) the ratio of maximum and full-load torque (ii) the speed at which the maximum

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Three Phase Induction Mot... The relative speed of stator magnetic field with respect to rotor of a 30 induction motor with 4 pole, 50 Hz frequency. If the slip is 0.05.
Frequency is 60Hz...