Cost analysis follow-up for electric motors

Tags: motors

Question: "At what percentage efficiency would you consider a motor to be too large for its application?"

Answer: Motor efficiency should not be the only indicator for determining an oversized motor for an application. Motor efficiency often only varies 1 to 2 percent between no load and full load. This is an often overlooked detail in cost analysis. A 100-horsepower motor supplying a 60-horsepower application may still run within 2 percent of its designed efficiency. The right approach is to compare the power required to deliver 60 horsepower from a 100-horsepower motor operating at the low end of its efficiency range vs. the power required to deliver 60 horsepower from a 60-horsepower motor operating at the top of its efficiency range."