Impact of armature rewinding on induction motor efficiency in South Africa
Master Thesis
2009
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University of Cape Town
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Abstract
The aim of this thesis is to evaluate the impact of armature rewinding on the efficiency of Low Voltage (LV) industrial squirrel cage induction motors in South Africa. The efficiency of an electric motor is a measure of the effectiveness of the motor to convert electrical power at its terminals to mechanical power at its shaft. Although the definition is seemingly simple and straightforward, the determination of the efficiency of an induction motor is a much-debated topic. Motor manufacturers provide efficiency data obtained through measurement and calculation according to a variety of international standards. Several international standards exist, with each outlining different methods and procedures for the determination of induction motor efficiency. Most notable among the disparities is the treatment of stray losses. For example, the Japanese standard JEC-37 assumes stray losses to be negligible, others such as SANS 34-2 and ASINZ 1359.5 use a fixed value, while IEEE 112, CSA 390 and lEC 34-2 prefer to make actual measurements. A number of these standards were initially considered. However, after preliminary laboratory-tests were performed, it was observed that the IEEE 112 method B (2004) and IEC 60034-2 segregation method (2007) appeared to be the most consistent and repeatable. The two standards were therefore preferred and subsequently chosen for this project. The South African standard, SANS 34-2, is available but its methods of determining efficiency have been found to be unsupported due to its reference to the IEC 60034-2 (1984) which has been abandoned and replaced. The SANS 34-2 was therefore not used in the testing.
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Includes bibliographical references (p. 162-168).
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Mzungu, H. 2009. Impact of armature rewinding on induction motor efficiency in South Africa. University of Cape Town.