9. A 3-ô induction motor has a synchronous speed of 250 r.p.m. and 4 per cent slip at full-load. The rotor has a resistance of 0.02 /phase and a standstill leakage reactance of 0.15 Q/phase. Calculate (a) the ratio of maximum and full-load torque (b) the speed at which the maximum torque is devel- oped. Neglect resistance and leakage of the stator winding. |(a) 1.82 (b) 217 r.p.m.] (London University)

9. A 3-ô induction motor has a synchronous speed of 250 r.p.m. and 4 per cent slip at full-load. The rotor has a resistance of 0.02 /phase and a standstill leakage reactance of 0.15 Q/phase. Calculate (a) the ratio of maximum and full-load torque (b) the speed at which the maximum torque is devel- oped. Neglect resistance and leakage of the stator winding. |(a) 1.82 (b) 217 r.p.m.] (London University)

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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Similar questions

A three-phase induction motor, operating at rated voltage and frequency, has a startingtorque of 1.35 times and a maximum torque of 2.2 times, both with respect to its rated-loadtorque. Ignoring the effects of the stator resistance and rotational losses and assumingconstant rotor resistance, determine the slip at the maximum torque;
A three-phase induction motor, operating at rated voltage and frequency, has a startingtorque of 1.35 times and a maximum torque of 2.2 times, both with respect to its rated-loadtorque. Ignoring the effects of the stator resistance and rotational losses and assumingconstant rotor resistance, determine the slip rated load, and the rotor current at starting (as a percentage of the rotor current at rated load). The slip at maximum torque is 0.343 if that helps.
a. A three-phase, 220-V, 60-Hz induction motor runsat 1,140 r/min. Determine the number of poles (forminimum slip), the slip, and the frequency of therotor currents.b. To reduce the starting current, a three-phasesquirrel cage induction motor is started byreducing the line voltage to Vs/2. By what factorare the starting torque and the starting currentreduced?
A three-phase induction motor, at rated voltageand frequency, has a starting torque of 140 percentand a maximum torque of 210 percent of full-loadtorque. Neglect stator resistance and rotational lossesand assume constant rotor resistance. Determinea. The slip at full load.b. The slip at maximum torque.c. The rotor current at starting as a percentage offull-load rotor current.
A 3-phase, 6-pole induction motor is rated 400Hz, 150V, 10hp, 3% slip at rated power output. The windage and friction loss is 200W at rated speed. With the motor operating at rated voltage, frequency, slip, and power output, determine the output torque.
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Q/ A 3-phase squirrel-cage induction motor, at rated voltage and frequency, has a maximum torque of 225 percent and starting torque of 150 percent of full-load torque. Neglect stator resistance and rotational losses and assume costant rotor resistance. Calculate:i) the slip at maximum torque.ii) the slip at full load.
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A 400V, 50Hz, 6-pole 3-phase asynchronous motor rotates 20Nm of constant load torque at 950rpm. If it is desired to rotate this load at 750 rpm mechanical speed;a) The synchronous speed of the motor,b) Supply frequency,c) Find the value of the supply voltage between phases?Note: The motor will be driven with V/F sbt because the load torque does not change.
A synchronous motor has a synchronous reactance of 0.8 pu and a transient reactance of 0.25 pu. The motor is connected to an infinite bus. The field current is adjusted such that the unloaded motor draws half the rated current at zero power factor lagging. With the field current left unchanged find the following: a) Find the maximum per-unit torque that can be applied gradually without losing synchronism b) Find the maximum per-unit torque that can be applied suddenly without losing synchronism.
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