Abstract
In the late 19th century, the three-phase induction motor was the central element of productivity increase in the second industrial revolution in Europe and the United States. Currently, it is the main load on electrical systems in global terms, reaching approximately 70% of electrical energy consumption in the industrial sector worldwide. During the 20th century, electric motors underwent intense technological innovations that enabled significant performance gains. Thus, this work analyses the performance changes in squirrel-cage rotor three-phase induction electric motors (SCIMs) with mechanical powers of 3.7 kW, 37 kW, and 150 kW and speed ranges corresponding to two poles and eight poles, connected to a low voltage at a frequency of 60 Hz and tested between 1945 and 2020. The study confirms accumulated performance gains of above 10% in some cases. Insulating materials for electrical conductors have gone through several generations (cotton, silk, and currently, varnish). Improvements to the housing for cooling, the bearings, the quality of active materials, and the design were the elements that enabled the high gains in performance. The first commercial two-pole SCIM with a shaft power of 4.4 kW was marketed in 1891, with a weight/power ratio of 86 kg/kW, and until the 2000s, this value gradually decreased, eventually reaching 4.8 kg/kW. Between 2000 and 2020, this ratio showed a reversed trend based on improvements in the performance of SCIMs. More active materials were used, causing the weight/power ratio to reach 8.6 kg/kW. The MEPS (minimum energy performance standards) of SCIMs had an essential role in the performance gain over the last three decades. Data collection was via tests at the Electrical Machines Laboratory of the Institute of Energy and Environment of the University of São Paulo. The laboratory has a history of tests on electrical equipment dating from 1911.
Highlights
Introduction iationsThe production of mechanical force was one of the fundamental human demands in the transformation process that took homo sapiens from an animal in nature like the others to the construction of megacities and technological mastery [1].The process of producing mechanical force went through several phases
Direct-current motors were on the market, and alternating-current motors were in the full developmental stage, with research ongoing in Europe and the United States
It is common to read in the technical literature that “squirrel-cage rotor three-phase induction electric motors (SCIMs) have hardly changed in the last 100 years”
Summary
The production of mechanical force was one of the fundamental human demands in the transformation process that took homo sapiens from an animal in nature like the others to the construction of megacities and technological mastery [1]. The process of producing mechanical force went through several phases. The domestication of animals represented an essential step in automation and the increase in labour productivity, necessary for changing the way of life from hunter and gatherer to farmer/shepherd [2]. With the use of other domesticated animals, homo sapiens could perform an activity without the need to use muscular strength directly [3]. The production of mechanical force was primarily responsible for the first two great industrial revolutions. The first industrial revolution began in England around 1750–1760, lasting until somewhere between 1820 and 1840, and was marked by the development
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