Motor selection for centrifugal pump applications made easy

Due to the renewed interest in energy saving, it has become more popular to utilize Electrical Variable Frequency Drives (EVFD) to power pumps which results in significant energy savings versus mechanical means for adjusting the flow of the pumping system. Due to the characteristics of pumps it is easy to misapply motors in EVFD pump applications. This paper will present some of the characteristics of the frequently used pumps and how these characteristics affect the motor selection (speed, torque and power ratings). Included will be real life examples of some often made mistakes in selecting the correct motors for these pumps. Primarily this discussion will be in regard to centrifugal pumps.