Improving Reliability In A High Static Head System Through VFD Application

Abstract

The static head content in the total head of a pumping system (static head factor - fHS) plays an important role on energy and reliability potential gains attainable with the use of variable speed (VS) controls in pumping system. In spite of this control method almost always enable important gains when compared to throttle control at constant speed, as a rule of thumb “the higher the fHS, the smaller the energy and reliability gains and the higher the risk of facing an unstable pumpage (sinusoidal shape flowrate).” The main point of this presentation is to demonstrate that even in pumping systems with fHS as high as 80 percent it is still possible to save large amounts of energy and improve reliability besides an effective control of the pumpage variable. First the present case will be described. Second, fundamental concepts of control under variable speed will be brought up in order to facilitate understanding of the applied methodology. Third, the calculation approach and graphical analysis will be shown step by step and the applied solutions will be detailed as well. Finally field record will be shown and discussed.