What contributed to the reduction of the weight-to-power ratio of electric motors was the development of enamelled conductors, paper or synthetic insulation films, magnetic plates, aluminum alloys and plastic materials.

Looking at the weight of an electric motor with the same power over time, we can see that the current engine has only 8% of its weight in 1891.

This technological evolution is characterized by the development of new insulation materials, which support very high temperatures. Currently electric motors are used in virtually all industrial, commercial and residential facilities.

Comparing data from different manufacturers, from different times we can verify that there was a reduction of weight and reduction of the size of the engine, for the same power. This reduction was approximately 20% in each decade, less in the last two, because the reduction was less pronounced.

The need for periodic revision of the standards, which adapt the relationship between potencies and carcass size, through technological development has been proven.

Examples are the tiny motors PN-207T that power the hard drives of computers, which drive home appliances and the giant motors that drive pumps, compressors, mills, among others.