Author: S.W. “Butch” Summey III, Automation Sales Engineer – Southeast, WEG Electric Corp
The Peachtree City Water and Sewerage Authority (PCWASA) owns and operates two wastewater treatment facilities and manages 35 pumping stations that serve the residents of Peachtree City, Georgia. In 2017, the PCWASA worked with WEG to retrofit their master lift station, which collects wastewater from all the other sewage lift stations in this municipal sewage system and transports it to the nearby wastewater treatment plant.
Photo Courtesy of The Peachtree City Water and Sewerage Authority (http://pcwasa.org/)
The master lift station operates 6 submersible grinder pumps – (3) 60-horsepower and (3) 30-horsepower – to move wastewater out of the tank and through the pipes to the wastewater treatment facility. The lift station had been relying on float switches and back-up pressure sensors to indicate high pressure in the collection tank. As the pressure in the tank increased, the signal would be sent to the pumps to accelerate to full speed so the tank could be emptied. Operating the pumps in this way had been causing excessive wear and tear on the pumps, so the PCWASA took a proactive step to reduce maintenance costs and extend the mean-time-between-repair for these pumps.
Initially, the PCWASA discussed retrofitting the system with analog sensors and self-starters, but eventually decided that WEG Variable Frequency Drives (VFDs) with Pump Genius automation would be a more economical solution. The CFW 11 Pump Genius Multiplex system was selected for its ability to automate the pump motors, which could be programmed to start and stop in a way that would equalize the run times on each pump.
In December 2017, 6 WEG VFDs were installed at the master lift station – all controlled by WEG Pump Genius. This self-contained, alternating system monitors the runtime of the individual pumps and automatically operates the pumps in a rotating sequence based on each pump’s runtime. So the pump with the least amount of runtime will take the lead when demand requires it.
Having intelligent VFDs that essentially “talk” to each other allows pumps to be accelerated or backed off when they are not needed, thereby reducing energy usage and spreading out the amount of wear and tear on the pumps over a longer period of time. The MTBR for these submersible grinder pumps is expected to double, saving the municipality a significant amount in maintenance costs.
About WEG Electric Corp.
Founded in 1961 in Jaraguá do Sul, Brazil by Werner Ricardo Voigt, Eggon João da Silva and Geraldo Werninghaus, WEG is a $3.5B independent international solutions company operating in 6 continents, exporting to 135+ countries with production facilities in 12 countries and 30,000+ employees (200+ located in the United States). WEG’s Duluth, GA Headquarters facility manufactuers custom panels and medium voltagel drives. U.S. Customers are served nationwide by WEG’s 8 Regional Distribution Centers located in Chicago, IL; Duluth, GA; Harrisburg, PA; Houston, TX; Ontario, CA; Kansas City, KS; and Portland, OR. Learn more by visiting www.weg.net.