Technology of Energy-Efficient Motors

Abstract

Electric motors function as energy converters changing electrical to mechanical energy and are one of the most efficient means of energy conversion known. Although some losses do occur in the conversion process, the majority of the electrical energy which enters the motor is converted to mechanical form and delivered to the load. Consider Fig. 2.1 which shows a 50-hp motor driving a pump of equivalent rating. The power distribution is shown in the figure. The electrical input into the motor is 41.2 kW and, of this amount, 37.3 kW is converted and delivered to the pump. This 37.3 kW is expended by the pump in circulating the fluid that it is pumping plus, of course, any losses occurring in the pump. The motor losses account for the difference between the incoming electrical power and the converted power delivered to the pump which, in this case, is 3.9 kW. The motor’s efficiency is 90.5%.