A 3-phase, Y=-connected, 440 V, 20-kW, 50 Hz, 1450 rpm wound roto induction machine has the following parameters in ohms: R, = 0.25 R = 0.2, X, = 1.0, X; = 0.8 and Xm = 30, where R, and X are referred to stator. The total friction, windage and core losses may be assumed to be constant at 1000 W, independent of load. (a) Draw the approximate equivalent circuit. (b) Using the approximate equivalent circuit in (a), operating as a motor determine (i) the full-load developed torque (ii) the maximun developed torque and the corresponding speed (iii) the starting torque. (c) How much resistance must be inserted in the rotor circuit to bring the machine speed at maximum torque down to 1250 rpm?

A 3-phase, Y=-connected, 440 V, 20-kW, 50 Hz, 1450 rpm wound roto induction machine has the following parameters in ohms: R, = 0.25 R = 0.2, X, = 1.0, X; = 0.8 and Xm = 30, where R, and X are referred to stator. The total friction, windage and core losses may be assumed to be constant at 1000 W, independent of load. (a) Draw the approximate equivalent circuit. (b) Using the approximate equivalent circuit in (a), operating as a motor determine (i) the full-load developed torque (ii) the maximun developed torque and the corresponding speed (iii) the starting torque. (c) How much resistance must be inserted in the rotor circuit to bring the machine speed at maximum torque down to 1250 rpm?

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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