Committee Chair

Eltom, Ahmed H.

Committee Member

Carney, Terrence M.; Parten, Clifford R.; Smullen, Stephanie A.

Department

Dept. of Electrical Engineering

College

College of Engineering and Computer Science

Publisher

University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)

Abstract

This study investigates induction motor performance during a variety of system and load conditions. A computer simulation is used to characterize the motor behavior during normal operation, lockedrotor case, high inertia loading, and overloading conditions. Motor temperature at critical points is estimated. A microprocessor protection scheme based on motor temperature is proposed. Previous studies assume a linear relationship between motor impedance and frequency when calculating motor temperature. In this study an electrical model, based on Maxwell's equations, is used in conjunction with a mechanical model, to represent the motor during dynamic state conditions. The model accounts for the rotor bar skin effect as the motor speed changes. Motor losses, computed using the electrical model, are fed to a thermal model. Stator, rotor, and core temperatures are calculated. Thermal limit curves are presented. Protection strategies are investigated. A microprocessor based scheme is recommended. The scheme responds to motor temperature and trips the motor only at critical conditions. The scheme is optimal, simple, and easy to implement. The diagnostic capability of this work is also valuable. For example, the motor acceleration time for a specified load can be calculated by this computer simulation. Thus, if the acceleration time changes it shows that there is a problem in a motor bearing or in some other mechanical part.

Degree

M. S.; A thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Master of Science.

Date

5-1989

Subject

Electric motors, Induction

Discipline

Electrical and Computer Engineering

Document Type

Masters theses

Extent

xii, 131 leaves

Language

English

Call Number

LB2369.2 .M61 1989

Rights

Under copyright.

License

http://creativecommons.org/licenses/by-nc-nd/3.0/

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