Four high-efficiency 100 kW Flygt N-pumps operating with variable frequency drives (VFDs) deliver a total volume of 0.8 m3/s (12,700 US gpm) and consume 1,000,000 kWh of energy per year. The customer wanted to reduce energy costs but maintain reliable, trouble-free operation without the problems of clogging, sedimentation and floating debris.
We performed an energy audit by measuring flow, head, power and analyzing the control philosophy. By analyzing the results from the measurements, we identified that adjustment of the settings on the VFDs would lead to more energy-efficient operations. Estimated energy savings amounted to between five and 15 percent.