2 A Triac control of a three-phase, 30 kW, 400 V, 50 Hz, six-pole, star-connected squirrel-cage induction motor such that it operates at a full loadefficiency of 0.85 p.u. and power factor 0.8 lagging. Calculate the averageand rms current rating and maximum voltage rating required of the triacs.[Ans: 32 A, 45 A, 326 VJ3The motor in Problem 15.2 drives a load characterised by the relationT₁ = ko where T₁ is the shaft torque and w is the motor speed. Operationis required to give rated torque at rated speed of 960 rpm and also tosupply the appropriate load at speed of 640 rpm at which the power factoris dropped to 0.6. If the motor operates at full voltage at its upper speed,estimate roughly, the change of thyristor firing-angle necessary to achievesatisfactory operation of the motor at the lower speed. Assuming that themotor impedance is unchanged between the two speeds.[Ans: 37° ≤ a ≤90°]

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2 A Triac control of a three-phase, 30 kW, 400 V, 50 Hz, six-pole, star- connected squirrel-cage induction motor such that it operates at a full load efficiency of 0.85 p.u. and power factor 0.8 lagging. Calculate the average and rms current rating and maximum voltage rating required of the triacs. [Ans: 32 A, 45 A, 326 V] 3 The motor in Problem 15.2 drives a load characterised by the relation T₁ = koo where T₁ is the shaft torque and wo is the motor speed. Operation is required to give rated torque at rated speed of 960 rpm and also to supply the appropriate load at speed of 640 rpm at which the power factor is dropped to 0.6. If the motor operates at full voltage at its upper speed, estimate roughly, the change of thyristor firing-angle necessary to achieve satisfactory operation of the motor at the lower speed. Assuming that the motor impedance is unchanged between the two speeds. [Ans: 37° ≤a ≤90°]

2 A Triac control of a three-phase, 30 kW, 400 V, 50 Hz, six-pole, star- connected squirrel-cage induction motor such that it operates at a full load efficiency of 0.85 p.u. and power factor 0.8 lagging. Calculate the average and rms current rating and maximum voltage rating required of the triacs. [Ans: 32 A, 45 A, 326 V] 3 The motor in Problem 15.2 drives a load characterised by the relation T₁ = koo where T₁ is the shaft torque and wo is the motor speed. Operation is required to give rated torque at rated speed of 960 rpm and also to supply the appropriate load at speed of 640 rpm at which the power factor is dropped to 0.6. If the motor operates at full voltage at its upper speed, estimate roughly, the change of thyristor firing-angle necessary to achieve satisfactory operation of the motor at the lower speed. Assuming that the motor impedance is unchanged between the two speeds. [Ans: 37° ≤a ≤90°]

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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