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An Introductory Electric Motors And Generators Experiment For A Sophomore Level Circuits Course

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Conference

2008 Annual Conference & Exposition

Location

Pittsburgh, Pennsylvania

Publication Date

June 22, 2008

Start Date

June 22, 2008

End Date

June 25, 2008

ISSN

2153-5965

Conference Session

DELOS Best Paper Nominations

Tagged Division

Division Experimentation & Lab-Oriented Studies

Page Count

17

Page Numbers

13.192.1 - 13.192.17

Permanent URL

https://peer.asee.org/3232

Download Count

602

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Paper Authors

biography

Thomas Schubert University of San Diego

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Thomas F. Schubert, Jr. received his B.S., M.S., and Ph.D. degrees in electrical engineering from the University of California, Irvine, Irvine CA in 1968, 1969 and 1972 respectively.
He is currently a Professor of electrical engineering at the University of San Diego, San Diego, CA and came there as a founding member of the engineering faculty in 1987. He previously served on the electrical engineering faculty at the University of Portland, Portland OR and Portland State University, Portland OR and on the engineering staff at Hughes Aircraft Company, Los Angeles, CA.
Prof. Schubert is a member of IEEE and ASEE and is a registered professional engineer in Oregon. He currently serves as the faculty advisor for the Kappa Eta chapter of Eta Kappa Nu at the University of San Diego.

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Frank Jacobitz University of San Diego

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Ernest Kim University of San Diego

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Abstract
NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

An Introductory Electric Motors and Generators Experiment for a Sophomore-Level Circuits Course

Abstract

The design, implementation, and assessment of an introductory electric motors and generators experiment in sophomore-level electric circuits courses are described. Two separate courses were enhanced by the addition of a common motors experiment for both students in the electrical engineering program (e.g., as student preparation for an electric power class) and those in other engineering majors (e.g., as student preparation for mechanical engineering lab experiences). The experiential foundation in the motors lab was designed to solidify concepts on efficiency of energy conversion and on motor performance. Topics included modeling of electric motors, predicting motor performance, and experimentally obtaining relevant motor constants. The experiment used a simple sub-fractional horsepower (Fischertechnik #32293: ~1.5 Watt) electric motor together with a unique small-scale dynamometer. In the experiment, students were required to experimentally determine the rotational speed of a motor using an optoswitch- based tachometer to find the motor voltage constant, kE; to determine motor torque constant, kT; to explore the use of a dynamometer to measure the conversion of electrical energy into mechanical energy; and to investigate the use of a motor as a generator. Despite the low-cost equipment, experimental results proved to be reliable, accurate, and repeatable. For example, the motor kE – kT match was typically found to be within 5%. Student learning was assessed through questionnaires at the beginning and end of the laboratory period. The questionnaires addressed both student knowledge and student confidence levels. The assessment showed a significant overall increase of both student knowledge and confidence scores as well as significant incremental increases. The data also showed that each incremental increase could approximately be represented as a normal distribution. Detailed analysis of the assessment data revealed strengths in student preparation for the experiment as well as certain course topics, such as the operating principles of a dynamometer, which will require more in-depth coverage in subsequent offerings of the course.

I. Introduction

Responding to a recent resurgence in interest concerning basic electric machines and their control1 has been a challenge for many electrical engineering programs that, either through retirement of elderly equipment or the failure to acquire equipment, have been caught without proper resources for laboratory exploration of electric machines, in particular in introductory electrical circuits courses. The University of San Diego (USD) falls into the latter category with an electrical engineering (EE) curriculum focused on the electronics and communications industries rather than on electrical machines. Recent additions of a mechanical engineering (ME) program and an industrial & systems engineering program to the existing electrical engineering (EE) program have altered the student population balance and, necessarily, have shifted the focus of many lower division courses. In response to these changes, the one- semester, sophomore-level electric circuits curriculum was changed. Prior to the change, all engineering students enrolled in a single course designed primarily to meet the needs of EE students. After the change, a second course was added with a more diversified content to meet

Schubert, T., & Jacobitz, F., & Kim, E. (2008, June), An Introductory Electric Motors And Generators Experiment For A Sophomore Level Circuits Course Paper presented at 2008 Annual Conference & Exposition, Pittsburgh, Pennsylvania. https://peer.asee.org/3232

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