Most Motors Do Not Operate at Optimum “Full Load Rating”

Electric induction motors very seldom operate at their optimum full load point creating costly energy inefficiencies. There are several reasons for this.

Most motors are selected with a safety factor to ensure they do not become overloaded during normal operation. This ensures longevity since overloaded motors will operate above their full load current rating and generate excessive winding temperatures.

Since motors are available with specific HP ratings, for example 10, 15, 20 and 25 HP, the designer will normally upsize to the next HP rating above the actual required HP. This results in operation at less than full load rating.

Variable torque requirements, commonly centrifugal fans and pumps, are normally operated at less than full load. This is common practice in both industrial applications as well as HVAC. This is an inherent issue with these types of applications since the motors are designed to handle the maximum demand of the system. These situations are commonly addressed by adding dampers to fans or throttling valves to pumps. These solutions add greatly to the system inefficiencies.

Solutions to ensure right sizing of motors and minimizing system inefficiencies:

–       Careful monitoring of motor load throughout its operating range to evaluate proper sizing of the motor to the application.

–       Evaluating the addition of VFD’s to enable operation at a wide range of output speeds to meet system requirements while maximizing efficiencies.

–       A typical fan or pump system requiring only 50 % Flow can result in an energy savings of approximately 80% when operated on a VFD. The technical specialists at Flolo Corporation have extensive knowledge of proper motor sizing and application of VFD’s to ensure maximum system efficiency while maintaining reliability. This knowledge comes from working with a wide variety of end users as well as Equipment OEMs. This coupled with the fact that Flolo works with reputable suppliers ensures that the best product for your specific application is selected.