Problem 3 A 208-V, three-phase, Y-connected, synchronous motor load is 7.2 kW at 0.8 pf leading. The synchronous reactance of the motor is 4 ohm/phase and the armature-winding resistance is negligible. If the field excitation is adjusted to decrease the excitation voltage by 50% while the load on the motor remains the same, determine (a) the new torque angle, (b) the new armature current, and (c) the new power factor.

Problem 3 A 208-V, three-phase, Y-connected, synchronous motor load is 7.2 kW at 0.8 pf leading. The synchronous reactance of the motor is 4 ohm/phase and the armature-winding resistance is negligible. If the field excitation is adjusted to decrease the excitation voltage by 50% while the load on the motor remains the same, determine (a) the new torque angle, (b) the new armature current, and (c) the new power factor.

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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Concept explainers

Three Phase Induction Motor

The induction motor is an electric motor that runs on AC (alternating current) and it is of two type single phase motor that work on single-phase power supply and three-phase motor that work on three-phase power supply.

Question

Problem 3
A 208-V, three-phase, Y-connected, synchronous motor load is 7.2 kW at 0.8 pf leading. The synchronous
reactance of the motor is 4 ohm/phase and the armature-winding resistance is negligible. If the field
excitation is adjusted to decrease the excitation voltage by 50% while the load on the motor remains the
same, determine (a) the new torque angle, (b) the new armature current, and (c) the new power factor.

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