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Optimised for pump applications

19 November 2020

When water industry expert SUEZ Water Technologies & Solutions needed 12 AC variable speed drives to control skid-mounted booster pumps, Danfoss VLT Aqua drives were an ideal choice

This project posed two interesting challenges: how to make convenient and cost-effective provision for cascade operation of multiple pumps, and how to avoid delays in setting up and commissioning the drives at a time when the COVID-19 pandemic made it impossible for Danfoss engineers to visit the SUEZ site.

For customers that have an urgent need for extra pumping capacity, SUEZ offers skid-mounted booster pumps that can quickly be delivered to site and put into service. The pumps can be used individually or, where greater capacity is needed, two or more pumps can be used in combination. When multiple pumps are used, they are typically arranged for cascade operation, where individual pumps are automatically turned on (staged) and turned off (de-staged) as needed to meet flow or pressure requirements. The speed of the pumps is also adjusted automatically to provide a continuous range of control over the output.

The drives chosen for this project were Danfoss VLT Aqua Drives rated at 30 kW. The IP20 versions were used and fitted in stainless-steel enclosures mounted on the pump skids.

“There were numerous reasons we chose Danfoss VLT Aqua Drives for this application, but global availability and compliance with global standards were two of the most important," said Sam Hemmings, project engineer at SUEZ. "Our products can be shipped almost anywhere in the world at a moment’s notice so we need to be sure that they’re standards compliant wherever they may end up, and also that, if we need local support for a system that’s on site, it will be readily available.

“Other important factors that influenced our decision to buy Danfoss drives were excellent value for money, proven reliability and performance, and the responsiveness of the Danfoss team when we had questions or special requirements.”

Danfoss VLT Aqua Drives have long supported cascade operation but have always required additional hardware and extra connections between the drives to implement it. While this would in principle have been satisfactory for SUEZ, the company was looking for a simpler option that would, in particular, eliminate the need for the additional connections between the drives. This was important because the booster pumps are supplied as a “plug-and-play” solution that requires a minimum of on-site configuration and set up.

New firmware

With this in mind, engineers at Danfoss developed new firmware for the drives which supports cascade operation entirely over the Modbus connection that SUEZ uses to provide overall control for its installations. With the new firmware, no additional connections are needed between the drives, which simplifies installation on site and reduces the risk of errors. In addition, this new solution provides full cascade control without the need for extra hardware, reducing cost and complexity.

With the new firmware, no additional connections are needed between the drives, which simplifies installation

“The new firmware did exactly what we wanted, but now we faced another challenge," said Hemmings. "As this was the first time this solution had been used, we wanted support from Danfoss to help us commission the drives. This was not only to evaluate the new arrangement for cascade operation, but also to ensure that the drives were optimally configured for performance and economy. Normally this would have been no problem, but because of the Covid-19 pandemic restrictions, the Danfoss engineers couldn’t travel to our factory.”

Working together, engineers from SUEZ and Danfoss devised a solution based on the use of TeamViewer, a proprietary software package that allows remote access to a computer using technologies that provide fast response and robust security. With the aid of this package in conjunction with the free downloadable Danfoss MyDrive software toolkit and MCT10 programming software, the Danfoss engineers were able to sit at their own desks and view the desktop of a computer connected to the VLT Aqua Drives in the SUEZ factory just as if they were working locally. The engineers at the two companies also talked to one another by phone while they were configuring and commissioning the drives.