VFD Combo Helps Dutch Utility Reduce Energy

Utility Evides Waterbedrijf has pioneered the first use of synchronous reluctance motor and variable frequency drive (VFD) technology in the Netherlands. Energy savings achieved with the motor-drive solution are estimated to be around 20 percent compared to previous processes.

By Ari Tammi

Evides Waterbedrijf provides drinking water to 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 manufacturing processes to companies throughout the Netherlands, as well as offering industrial water consulting services in numerous countries.

“The philosophy of Evides is to lower our carbon footprint and look for energy savings in innovative ways such as energy saving motor and drives combinations, or the solar panels that we are installing on some buildings,” says Joost van Belzen, a project engineer at Evides.

To increase drinking water supply in the province of Zeeland, 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 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 cubic metres. In the summertime, when water demand is high both because of warmer weather and the influx of tourists to the region, the safety stock is sufficient to deliver water for at least six hours without taking new water in. The pumps provided by KSB are equipped with motors and drives from ABB. 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.

Toine Rijsdijk, an Evides process automation engineer who worked on the project, says: “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. After two years of running we have not had any problems.”

Upgrade: The project involved a two-street pumping station to replace older stations, to ensure continuous operation

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 life-time. The motor, therefore, can run slower with cooler air and reduced noise due to the correla-tion between noise and speed.

Energy savings achieved with the motor-drive solution are estimated to be around 20 percent compared to induction motors used in the old stations. The new motors are also much cooler in operation, meaning heat and energy losses are lower.

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. In fact, the package has the best partial load curve as tested in accordance with the new IES package efficiency guidelines.

The ABB MNS low voltage switchgear system included a 1250A incoming supply emergency power generator and 1600A incoming supply transformer.

“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.

With proper maintenance, the solution customised specifically to the water company’s exact needs is expected to last for around 25 years.

Savings: the energy usage is reported to have been cut by 20 percent compared to previsouly used induction motors

“Previously, with older motor technology, we have experienced damage to motors and bearings due to the electric currents generated in the older rotor designs,” says van Belzen.

“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 equipment,” van Belzen explains.

Dietrich Houtepen, the production engineer at the new Nieuwdorp plant, adds: “We are required to deliver water to our customers with absolutely no interruption in supply. The access to fresh water is a civil right required by law in the Netherlands. Therefore, we can take no risks when implementing new technology.”

Ultimately it is Houtepen’s day-to-day responsibility to ensure stations run smoothly without any problems and the continuous supply of the water is guaranteed in the region.

“Downtime, meaning time which we cannot actually deliver drinking water to our customers’ homes in the region, is counted in seconds per year. When we saw ABB’s SynRM package we were confident of the long-term reliability of the technology. It is important when we are selecting equipment that it will run for years without any trouble.”

Ari Tammi is the product manager for VSD driven motors at ABB.