The part-load efficiency characteristics of motors were covered previously. If motors operate for long periods at reduced loads, be sure to study the part-load efficiency figures. Some manufacturers offer special models that are claimed to provide high efficiency at low loads.
Unfortunately, motor catalogs often omit part-load efficiency information. At the present time, the Motor Master program is the only comprehensive source of information on the part-load performance of 3-phase motors. The part-load performance of single-phase motors is still a blank area.
Power Rating