Efficiency and reliability assessments of retrofitted high-efficiency motors

The majority of electric motor applications are pumps, fans, blowers, and certain compressors that follow the load torque pattern described in this paper. It has long been known that simply replacing the old motor with a high-efficiency motor might not produce the expected efficiency gain. This paper suggests calculations for the effective efficiency and temperature rise of high-efficiency motors. The reliability in terms of temperature rise, downsizing, power factor, harmonics, mechanical structure, etc., are discussed.