Walter Scott, Jr. College of Engineering

Graduate Exam Abstract

David Springer
M.S. Final
Oct 08, 2007, 10AM
Shepardson 212
Experimental Three Phase Induction Motor Derating due to Thermal Stress caused by
Abstract: This thesis is an experimental verification to the NEMA standard MG-1 derating for induction machines according to incoming voltage unbalance. MG-1 derating graph correlates the amount of incoming voltage unbalance to the reduction in load level necessary to ensure similar motor lifespan.
This thesis approaches the maintenance of comparable motor lifespan by regulating the internal temperature conditions at the same levels during all incoming voltage conditions, unbalanced or balanced. By regulating load using internal temperature, one can prevent premature aging of windings, a typical culprit of shorter overall lifespan.
This thesis explains all the necessary background to this experiment, the reasons for approaching the standard, two different methods of calculating unbalance, and the specific details of the testing. The results the specific test motor disagrees with the standard significantly. The testing also found that each of the phases held a slightly different derating curve and thereby a blanket derating graph, while the most useful, is inherently questionable.
Adviser: Dr. George Collins
Co-Adviser: Dr. Ernesto Wiedenbrug
Non-ECE Member: Dr. Hiroshi Sakurai
Member 3: Dr. Anthony Maciejewski
Addional Members:
Program of Study: