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.

Single-phase induction motors account for a significant share of energy consumption in residential, commercial, and rural applications. However, unlike three-phase motors, they still lack specific regulation in Brazil. This paper aims to identify the main construction types of these motors and their performance characteristics, to map international regulations based on Minimum Energy Performance Standards (MEPS) and to assess the actual efficiency of motors available on the Brazilian market. The adopted methodology combined an extensive literature review with laboratory tests conducted in accordance with IEC Standard 60034-2-1, using a sample of 48 motors from various manufacturers. The results confirmed that split-phase, capacitor-start, permanent-split capacitor, and two-capacitor motors exhibit distinct performance characteristics that determine their suitability for different applications. The analysis of international regulation revealed that the European Union, the United States, and several other countries have already established normative criteria for single-phase motors, ranging from labelling requirements to the reach of MEPS. Finally, the analysis of the test results revealed that most single-phase motors available on the Brazilian market fail to meet the minimum efficiency levels established by the standards.