A 3-phase, slip-ring, induction motor with star-connected rotor has an induced e.m.f. of 120 volts between slip-rings at standstill with normal voltage applied to the stator. The rotor winding has a resistance per phase of 0.3 ohm and standstill leakage reactance per phase of 1.5 ohm. Calculate the rotor current/phase when running short-circuited with 4 percentslip.

A 3-phase, slip-ring, induction motor with star-connected rotor has an induced e.m.f. of 120 volts between slip-rings at standstill with normal voltage applied to the stator. The rotor winding has a resistance per phase of 0.3 ohm and standstill leakage reactance per phase of 1.5 ohm. Calculate the rotor current/phase when running short-circuited with 4 percentslip.

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...

See similar textbooks

Similar questions

The resistance and reactance per phase of the rotor of a 3-phase induction motor are 0.6 ohm and 5 ohms respectively. The induction motor has a star-connected rotor and when the stator is connected to a supply of normal voltage, the induced e.m.f. between the slip rings at standstill is 80 V. Calculate the current in each phase and the power factor at starting when (i) the slip-rings are shorted, (ii) slip-rings are connected to a star-connected resistance of 4 ohm per phase.
3.An induction motor has a rotor resistance and reactance at standstill of 0.1 ohm and 3.5 ohm respectively. At standstill the voltage induced to the rotor is 60volts per phase. If the slip is 5%, determine the rotor current
An 8 pole, 50 Hz slip ring induction motor runs at a slip of 2.67% on full load. The rotor resistance per phase of the winding is 0.2 ohm. What external resistance per phase must be added in the rotor circuit so that the motor now runs ate a slip of 17.33% such that the torque remains same in both the cases. (Ans: 1.1 ohm)
A 3-phase induction motor has a rotor resitance and standstill reactance of 0.1 ohm and 3.5 ohms per phase respectively. The rotor emf at a standstills is 60 volts per phase, for slip of 5% what is the power developed?
An 3-phase induction motor(IM) has full load slip = 0.5%. If the rotor circuit resistance is increased so that R2new =2R2old, then the slip at which the motor develops the same full load torque is=.. * ......
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.
Three phase slip ring induction motor gives a reading of 65 V across slip rings when at rest with normal stator voltage applied. The rotor is star connected and has an impedance of (0.8 + j6) ohm per phase. Find the rotor current when the machine is (i) at standstill with the slip rings joined to a star-connected starter with a phase impedance of (4+j3) ohms and (ii) running normally with a 5% slip.
Problem #2: A 3-phase induction motor has a star-connected rotor. The rotor emf (between slip rings) at standstill is 50 V. The rotor resistance and standstill reactance are 0.5 and 3 2, respectively. Find rotor current per phase (a) at starting with the slip rings short circuited (b) at starting with a star-connected rheostat of resistance 6 ohms per phase connected across the slip rings. (c) if the motor is running at a slip of 4%.
A three phase induction motor with supply frequency of 60 Hz , 6 poles. If the slip is 5 % at a certain load, determine (a) the synchronous speed, (b) the speed of the rotor (c) the frequency of the induced e.m.f in the rotor and (d) speed of the induction motor if the slip changes to 6.75 %
What are the various losses in an induction motor? On what factors do they depend? IV. V. List the different types of stray load losses in an induction motor.
2) the armature windings of a 12-pole DC machine are composed of 72 coils with 10 windings, and the windings are 5the layered wave is yellowish. The Rotor speed is 1000 rpm and the flux value per pole is 25mWb.Resistance of Armature windings, commutation windings and compensation windings is 70mΩ, 10mΩ and5mω. (a) the number of current paths in the machine, (b) the total number of conductors in Armature windings, (c) armature coefficient (constant)
6- In a stepper motor, how is the speed of rotation determined? a) By the current supplied to the motor. b) By the magnitude of the voltage applied. c) By the load applied to the motor. d) By the frequency of the waveforms used. 7- A transformer core is laminated to a) reduce hysteresis loss b) reduce eddy current losses c) reduce copper losses d) reduce all above losses 8- An induction motor with 580 r.p.m. speed at 60 Hz will have a) 8 poles b) 6 poles c) 4 poles d) 2 poles 9- If any two phases for an induction motor are interchanged a) the motor will run in reverse direction b) the motor will run at reduced speed c) the motor will not run d) the motor will burn 10- No-Load speed of which of the following motor will be highest? a) Shunt motor b) Series motor c) Short-Shunt compound motor d) Long-Shunt compound motor