Today electric motors are present in almost every industrial, commercial and residential facility and as an example, we have the tiny motors that connect the hard drives of the computers, the variety of motors that connect our appliances and the large motors that move ventilating pumps , mills, compressors, and other diversities of applications.
The design and research of enamelled conductors, synthetic insulation papers or films, magnetic sheets, aluminum alloys and plastic materials basically cooperated for the weight to power ratio of the motors. Analyzing the weight of a motor of the same power with the passage of time, we can verify that the current motor has only 8% of the weight of its precursor in 1891.
By comparing catalog data from different manufacturers at different times, we can see that there was a reduction in weight and, consequently, a decrease in the engine’s constructive size by approximately 20% in each decade, taking the last two, in which the reduction was less defined. RL32013B1
This demonstrates the necessity of periodic revision of the norms, in order to adjust the relation between powers and carcasses to the sizes reached through technological development. This technological development is fundamentally characterized by the creation of new insulating compounds, which tolerate higher temperatures.