Standards for Efficiency of Electric Motors

In this article, feasible minimum limits for IE4 class are analyzed, taking into account the estimated efficiency limits and rated efficiency for emergent or commercially best available line-start PMSM technologies. The presented results can be useful to set up future international standard super-premium or IE4-class levels/limits. The practicability and technical limits associated with the IE4-class efficiency levels are addressed, taking into account technical and economical limitations. It is expected that advanced technologies will enable manufacturers to design motors for the IE4-class efficiency levels, with mechanical dimensions compatible with the existing IMs of lower efficiency classes (e.g., flanges, shaft heights, or frame sizes as defined in standards EN 50347 and NEMA MG1). NEMA frames sizes are larger than the IEC frame sizes, allowing the use of more active materials. In addition, 60-Hz operation enables higher power density and higher efficiency levels with the same frame sizes.