A 4-pole, 3-phase, 50 Hz induction motor has a voltage between slip-rings on open-circuit of 520 V.The star-connected rotor has a standstill reactance and resistance of 2.0 and 0.4 2 per phaserespectively. Determine :(a) the full-load torque if full-load speed is 1,425 r.p.m.(b) the ratio of starting torque to full-load torque(c) the additional rotor resistance required to give maximum torque at standstill[(a) 200 N-m (b) 0.82 (c) 1.6 2] (Elect. Machines-II, Vikram Univ. Ujjain 1977)A 50-Hz, 8-pole induction motor has a full-load slip of 4 per cent. The rotor resistance is 0.001 Qper phase and standstill reactance is 0.005 2 per phase. Find the ratio of the maximum to the full-load torque and the speed at which the maximum torque occurs.[2.6; 600 r.p.m.] (City & Guilds, London)A 3-0, 50-Hz induction motor with its rotor star-connected gives 500 V (r.m.s.) at standstill betweenslip-rings on open circuit. Calculate the current and power factor in each phase of the rotor windingsat standstill when joined to a star-connected circuit, each limb of which has a resistance of 10 Q andan inductance of 0.03 H. The resistance per phase of the rotor windings is 0.2 Q and inductance0.03 H. Calculate also the current and power factor in each rotor phase when the rings are short-circuited and the motor is running with a slip of 4 per cent.[13.6 A, 0.48; 27.0 A, 0.47] (London University)A 4-pole, 50-Hz, 3-phase induction motor has a slip-ring rotor with a resistance and standstill reactanceof 0.04 Q and 0.2 Q per phase respectively. Find the amount of resistance to be inserted in each rotorphase to obtain full-load torque at starting. What will be the approximate power factor in the rotor atthis instant ? The slip at full-load is 3 per cent.[0.084 2, 0.516 p.f.] (London University)

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A 4-pole, 3-phase, 50 Hz induction motor has a voltage between slip-rings on open-circuit of 520 V. The star-connected rotor has a standstill reactance and resistance of 2.0 and 0.4 2 per phase respectively. Determine : (a) the full-load torque if full-load speed is 1,425 r.p.m. (b) the ratio of starting torque to full-load torque (c) the additional rotor resistance required to give maximum torque at standstill [(a) 200 N-m (b) 0.82 (c) 1.6 Q] (Elect. Machines-II, Vikram Univ. Ujjain 1977)

A 4-pole, 3-phase, 50 Hz induction motor has a voltage between slip-rings on open-circuit of 520 V. The star-connected rotor has a standstill reactance and resistance of 2.0 and 0.4 2 per phase respectively. Determine : (a) the full-load torque if full-load speed is 1,425 r.p.m. (b) the ratio of starting torque to full-load torque (c) the additional rotor resistance required to give maximum torque at standstill [(a) 200 N-m (b) 0.82 (c) 1.6 Q] (Elect. Machines-II, Vikram Univ. Ujjain 1977)

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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The rotor of a four-pole, 50 Hz slip-ring induction motor has a resistance of 0.2 0 per phase and runs at 1425 rpm at full-load. Determine the external resistance per phase which must be added to reduce the speed to 1200 rpm, the torque remaining same in both the cases.
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d) A 2-pole induction motor is fed with a 230 V, 50 Hz supply and is running at no load. i. Calculate its angular speed in rpm. ii. Explain how can we slow down the speed of the motor above, at no load? iii. Explain what will happen to the speed of the motor if we slowly add amechanical load to the motor.
Q2: A single-phase induction motor with a 4-pole, 50-Hz, 130-V, is rotating in the clockwise direction at a speed of 1450 rpm. Determine its per-unit slip (a) in the direction of rotation and (b) in the opposite direction. At standstill the rotor resistance is 15 Q, determine the effective rotor resistance in each branch.
A three-phase, 460 V, 98hp 1,60 Hz, four-pole induction machine delivers rated output power at a slip of 0.05. Determine: (i) The synchonous speed. (V) speed at half Load (ii) The motor speed. (iii) The rotor frequency. (iv) The slip speed. ...A... -
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A three-phase induction motor used for a commercial application in Oman 50HZ runs at 584 rpm at no load and at 546 rpm at full load. a) How many poles do this motor have? b) What is the percentage slip at full load? c) The frequency of the rotor currents when slip is 7 % d) The frequency of the rotor currents at standstill.
A three-phase, 460 V, 98hp 1,60 Hz, four-pole induction machine delivers rated output power at a slip of 0.05. Determine: (i) The synchonous speed. (V) speed at half Load (ii) The motor speed. (iii) The rotor frequency. (iv) The slip speed. ...A... -