7.The rotor resistances per phase of a 4-pole, 50-Hz, 3-phase induction motor are 0.024 ohm and 0.12ohm respectively. Find the speed at maximum torque. Also find the value of the additional rotorresistance per phase required to develop 80% of maximum torque at starting.[1200 r.p.m. 0.036 Q] (Elect. Machines, A.M.I.E. Sec. B, 1990)8.The resistance and reactance per phase of the rotor of a 3-phase induction motor are 0.6 ohm and5 ohms respectively. The induction motor has a star-connected rotor and when the stator isconnected to a supply of normal voltage, the induced e.m.f. between the slip rings at standstill is 80V. Calculate the current in each phase and the power factor at starting when (i) the slip-rings areshorted, (ii) slip-rings are connected to a star-connected resistance of 4 ohm per phase.[(i) 9.17 amp, 0.1194 lag (i) 6.8 amp, 0.6765 lag||Rajiv Gandhi Technical University, Bhopal, 2000]

7. The rotor resistances per phase of a 4-pole, 50-Hz, 3-phase induction motor are 0.024 ohm and 0.12 ohm respectively. Find the speed at maximum torque. Also find the value of the additional rotor resistance per phase required to develop 80% of maximum torque at starting. [1200 r.p.m. 0.036 2] (Elect. Machines, A.M.I.E. Sec. B, 1990) 8. The resistance and reactance per pbase of the rotor of a 3-phase induction motor are 0.6 ohm and

7. The rotor resistances per phase of a 4-pole, 50-Hz, 3-phase induction motor are 0.024 ohm and 0.12 ohm respectively. Find the speed at maximum torque. Also find the value of the additional rotor resistance per phase required to develop 80% of maximum torque at starting. [1200 r.p.m. 0.036 2] (Elect. Machines, A.M.I.E. Sec. B, 1990) 8. The resistance and reactance per pbase of the rotor of a 3-phase induction motor are 0.6 ohm and

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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Similar questions

Would a positive-rotating harmonic or a negative-rotating harmonic be more harmful to an induction motor? Explain your answer.
200 +21. If maximum torque of an induction motor is kg-m at a slip of 12%, the torque at 6% slip would be...... kg-m. 1 (a) 100 (b) 160 (c) 50 (d) 40 B, 1993)
B/ Fill in the blanks: TV ezur 1- In a three-phase induction motor iron losses in stator will be..... that in rotor. 2- In three-phase induction motors sometimes copper bars are placed deep in the rotor to........... 3- Blocked rotor test on induction motors is used to find out. R..., ke, X. 4- The maximum torque in an induction motor depends on .............and .....
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=.. * ......
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.
1. 2. 4. 4. •.. .... ..... .... E.g. • 2. A 3 phase, 460 V, 10hp, 60 Hz, four-pole induction machine delivers rated output power at a slip of 0.05. determine the a. Synchronous speed and motor speed b. speed of the rotating air gad field c. frequency of the rotor circuit d. Slip in rpm e. Speed of the rotor field relative to the i. rotor structure ii. Stator structure iii Stator rotating field f. haft torque of this motor at the rated load? ... .... Equivalent Circuit • The induction motor consists of a two magnetically connected systems: Stator and rotor • This is similar to a transformer that also has two magnetically connected systems: primary and secondary windings. • The induction motor is similar to the transformer with the excention that its secondarv windings are free to.
Q.14. What is slip in an induction motor? Q.15. What is the value of slip at start in an induction motor?
Q / What is the benefit, purpose and conclusions of making single-phase induction motors ..?
. Explain how the pulsating mmf of a single-phase induction motor may be considered equivalent to two oppositely-rotating fields. Develop an expression for the torque of the motor. A 125-W, 4-pole, 110-V, 50-Hz single-phase induction motor has the no-load rotational loss of 25 watts and total rotor copper loss at rated load of 25 watts at a slip of 0.06. At a slip s = 0.06, what is the power input to the machine ?
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.
In a three-phase switched reluctance motor having six stator poles and four rotor poles, the pole widths for the stator and rotor poles are the same, with φs = φr = 40°. The currents in the phase windings are applied when the inductances are increasing. Draw qualitively the current and torque wave- forms of each phase and the total torque developed by the motor for a square wave current having. (a) 40° width. (b) 30° width. (c) 20° width.
1- To control the speed of an induction motor, the supply frequency is reduced by 10%. For the same magnetizing current to remain constant, the supply voltage must be....... a) Reduced by 10%, b) Reduced by 20%, c) Increased by 10%, d) Increased by 20% 2. When maximum starting torqua ic ohtoinod