Pumping stations are constantly striving to find new ways to save energy and reduce CO2 emissions. One Dutch pumping station benefitted from a new low-energy motor and variable frequency drive (VFD) technology. The pumping station hopes to use 20% less energy by installing this equipment.
Sustainability Evides Waterbedrijf, the Dutch company which supplies much of the drinking and industrial water in the southwestern part of the Netherlands, takes both water supply and sustainability extremely seriously. Evides provides drinking water for 2.5 million clients in its home market which includes the southern part of the province of Zuid-Holland, the entire province of Zeeland, and the Brabantse Wal. The company also supplies industrial water for manufactur-ing processes to companies throughout the Netherlands, as well as offering industrial water consulting services in numerous countries.
Modern station To increase redundancy in drinking water supply in the province of Zeeland in the south-west part of the country, Evides recently built a new pumping station near the small village of Nieuwdorp. The modern station was designed in cooperation with the local municipality and residents to ensure a natural integration into the landscape as well as silent operation.
The station building is hidden under grass banks on three sides, blending into the green countryside with a close-by industrial area looming in the horizon. “When the customer drives by, they only see a grass bank – they don’t see an ugly building, but a beautiful land-scape,” says Joost van Belzen, a Project Engineer at Evides.
The Nieuwdorp capacity expansion is an interesting and progressive project which is de-signed both to ensure the water supply in the region for the future, while at the same time making savings in the energy needed for pumping. The project involved a completely new ‘two-street’ pumping station which has replaced several older stations. This ensures that there is always at least one completely redundant pump set that can continue to perform in the event of malfunction of the other pump set, securing continuous operation.
Each street has three large 250 kW motors that pump purified water from three buffer-water storage reservoirs with a total capacity of approximately 12,000 m³. In the summertime, when water demand is high both because of warmer weather and the influx of tourists to the attractive region, the safety stock is sufficient to deliver water for at least six hours without taking new water in. The efficient pumps from KSB are equipped with motors and drives from ABB that ensure energy efficient pumping operation at the station.
New technology The Nieuwdorp project is a pioneering exercise for Evides as it is the first drinking water company to apply ABB’s energy-saving synchronous reluctance (SynRM) motor technology, controlled by ABB ACS880 industrial drives, in the water-supply business.
The water sector is known to be very careful about taking any risks that might disrupt water supply. “We wanted to be the first one in the Netherlands to experience the benefits that the SynRM motor offers in combination with the variable frequency drives,” says Toine Rijsdijk, an Evides Process Automation Engineer who worked on the project.
“I was closely involved in the choice of ABB’s SynRM motor-drive package solution. We saw that the potential benefits included significant energy savings, as well as cooler and quieter operation due to the fact that the motor has a special rotor design without any losses. We were convinced quickly and after two years of running we have not had any problems.”
The rotor geometry of the SynRM means it has no rotor-current energy losses, which in an induction motor can add up to a 40 percent total energy loss. Greater efficiency is therefore achieved with reduced energy losses, lower dissipated heat loss from the motor and a longer bearing lifetime. The motor, therefore, can run slower with cooler air and reduced noise due to the correlation between noise and speed.
Energy savings Energy savings and the resulting reduction in costs and CO2 emissions were the main reason for investing in the new technology, says van Belzen who was the Site Manager responsible for building the new Nieuwdorp water pumping plant. “Energy is a hot topic within the com-pany and the SynRM solution helps us save energy.”
Energy savings achieved with the motor-drive solution are estimated to be around 20 per-cent compared to induction motors used in the old stations. “The new motors are much cooler, meaning heat and energy losses are lower. In addition, the noise levels are much re-duced as well,” says van Belzen.
The SynRM motor-drive combination is much more energy-efficient than a typical IE4 motor, especially at partial load. This is very important considering that most pumps and fans are normally not used at full load. The SynRM technology is therefore particularly well-suited for pump and fan applications due to the large energy savings it can offer over a wide load range. In fact, the package has the best partial load curve as tested in accordance with the new IES package efficiency guidelines.
Another advantage, says Rijsdijk, is that “the operating system of the drive is very easy to use, for everyone. So it is accessible to everyone. Overall we are very satisfied and the motor is a success for us. We call it ‘the Golden Motor’.”
The partnership A key reason that Evides was comfortable with trying this new technology for the first time was its trust in the quality solutions and service they have received from ABB for a long time. Together with ABB MNS low voltage switchgear system including 1250A incoming supply emergency power generator and 1600A incoming supply transformer, the solution ensures personal and operational safety as well as reliability of the automation system in the new station.
Engineering of the complete system has been a joint effort with close cooperation between Evides and ABB. With proper maintenance, the solution customized specifically to the water company’s exact needs will last for around 25 years. The station adds up to the large installed base of ABB low voltage products as a result of a long lasting good relationship. “We have had the best experience with ABB quality concerning reliability, service, and engineering. The complete SynRM package convinced us that this was the optimal solution for the new Nieuwdorp station, and quality was the common denominator,” says Rijsdijk.
“We were just right on time finishing the project, and on budget,” van Belzen continues. He regards close cooperation and communication in project management as key success factors in extensive and complex projects such as building a new pumping station.
The future “Previously, with older motor technology, we have experienced damage to motors and bear-ings due to the electric currents generated in the older rotor designs,” van Belzen says. An independent Analysis Engineer examined the motors, drives and pumps, and verified the robustness of the technology.
“Everything was working as expected, and there was no damage from electrical fields and currents. This is important for the 20-30 year life expectancy that we have for this equip-ment,” van Belzen explains.