Moist towelettes contain plastic fibers, which makes them very durable. However, they do not dissolve in water as toilet paper does. Nonwoven products that are carelessly thrown into the toilet often become entangled, resulting in masses that can grow to several meters in length and many kilograms in weight. These braid-like masses can get tangled in the impellers of the wastewater pumps’. If a pump fails, wastewater builds up in the sewer and can frequently lead to very malodorous consequences. This is why wastewater disposal companies are seeking effective technical solutions to prevent this.
The pump cleaning function in the ACQ580 water dedicated variable speed drive (VSD) offers an intelligent way to resolve this problem. The VSD is designed for use in water and wastewater systems offering numerous features for pump applications that ensure the water to move through the pump safely.
The pump clean function is primarily used for wastewater applications. It has been designed to prevent solid particles from becoming stuck in the pump impeller. The function comprises a programmable sequence of forward and reverse rotations to loosen solids and release them from the impeller. This prevents blockages, thereby reducing the frequency of manual cleaning.
No more braid-like masses
Brandenburg-based Mittelmärkische Wasser- und Abwasser GmbH (MWA) serves the “Der Teltow” and “Mittelgraben” water and sewage associations. It has used the pump cleaning function in variable speed drives since 2014. Clogging occurs in their wastewater system when sanitary products accumulate in the pumps and form braid-like masses.
Bernd Zindel is foreman at MWA and is responsible for the wastewater division. He recalls:
“While conducting research, we came across the ABB VSD with reverse flow functionality. When the current increases due to clogging, the drive switches the pump into reverse operation or a higher speed. We haven’t experienced any clogging since then. We’re extremely satisfied with the cleaning function featured in these units.”
Pump cleaning is not the only ACQ580 feature that MWA uses. In all pumping stations managed by both water and sewage associations, the ramp functions for accelerating the pumps play an important role. These ramps allow the pressure to build up slowly and the pressure-side non-return valve will gradually open. This significantly reduces the load in the pipelines and reduces the risk of defective pressure lines or fittings. The ramp function also protects the system against pressure surges when the pump is switched off. These could occur if the non-return valve were to close abruptly.
Bernd Zindel points “During periods of heavy rainfall we try to dam the systems to relieve some of the burden on the pumping stations upstream. The ABB ACQ580 variable speed drives help us with these efforts by facilitating control of the flow of wastewater into the canal".