Increasing Water Pump Station Throughput by Introducing VFD-Based IE4 Class Synchronous Reluctance Motors with Improved Pump Control

Abstract

This paper outlines the reduction in energy consumption of motor-driven centrifugal pump systems by optimising key components of the system and controlling these from a system point of view. The latest developments in premium efficiency electric motors with variable frequency drive (VFD) control create an opportunity to retrofit older, motor-driven technology applications such as centrifugal pumping systems in an economically viable manner. A case study utilising a 132kW motor-driven pump installation with a delivery rate of 426m3/hr and servicing a head of 80m is studied, with the results following an energy efficiency upgrade being reported on. Energy efficiency is quantified by employing the International Performance Measurement and Verification Protocol (IPMVP) on the holistic system as opposed to the measurement of individual components as outlined in, amongst other standards for other components, the test methods for determining losses and efficiency of VSD-fed motors IEC 60034-2-3. The IPMVP protocol further provides the parameters for quantifying specific energy consumption improvement of a complete pump system. The pump system supplies water for public use in the northern region of South Africa. An overall energy saving of 36% for the complete pumping system is reported whilst maintaining unchanged water delivery; alternatively water pump station throughput can be increased by 58% without increasing energy consumption.