Quality and reliability of energy efficient motors

Even though the stage has been set for energy conservation being one of the major drivers in the design of general-purpose industrial motors, it was not intended to be at the expense of reliability or the overall motor performance. Some have felt that the drive for increased efficiency would diminish motor life and performance. This article is based on a review of various industrial motors available. The subject of this article is gaining interest and close scrutiny from many sources. In addition to the obvious energy savings, many users are beginning to see that the energy efficient motor offers increased reliability and longer life for most industrial applications. The product chosen for this comparison is the motor typically used for mill and chemical applications. The author discusses the basic design parameters, the reliability study methodology, efficiency and power factor trade-offs, winding thermal capacity, inrush current, speed and torque characteristics, inductive reactance to resistance ratio, motor safe stall times and bearings.