The Ashford Common water treatment plant, located in Surrey, England, is one of the largest water treatment plants in Europe. With a maximum output of approximately 7,870 liters of water per second, Ashford provides around a third of London's water supply. This large plant has five axial-flow pumps driven by 7.5-ton electric motors, each capable of pumping about 2,083 liters of water per second. The plant pumps and stores raw water from large reservoirs to be treated later.

In 2018, equipment breakdown became a real concern. Consequently, Thames Water looked to three of its suppliers to provide a replacement motor, and WEG was chosen to combat the high failure rates. According to Ashford engineers, one of the main reasons WEG stood out was that it offered a turnkey solution. WEG's offer to troubleshoot the problems and ensure that all the right equipment and staff were on-site was critical.

As the commissioning partner, a company that had already worked with both WEG and Thames Water, BGEN (formerly known as Boulting Group), was selected. BGEN provided on-site installation and project management in collaboration with WEG engineers.

WEG visited the site several times, inspected the existing motors, reviewed the configuration, and advised Ashford to go with a custom-assembled 600 kW, 415V, ten-pole WEG HGF high-performance motor due to its reliability and robustness. The HGF line is highly energy-efficient, with low maintenance costs and high-performance characteristics. This WEG HGF line is ideal for operating in critical environments such as water applications that require increased strength and durability.

The way the power cables would be connected to the motor required innovative solutions. Instead of having to cut the cables and then redo the connections—which is a difficult and physical job—WEG engineers suggested fabricating a custom terminal box to allow the connection to be made inside the junction box so that the existing board could be attached. This required a lot of precise measuring, as the cables have a set length and each cable is slightly different.

"Everything is oversized at Ashford," explained Iggy Pont Lezica, the technical operations leader at Ashford Common WTW. "This introduces complexity from an operational and maintenance standpoint. Finding suppliers that can meet our needs and have a forward-thinking approach and previous experience working at this scale is a challenge. WEG filled us with confidence right from the start," he adds.

The motor was replaced, and subsequently, due to the reliability results of the first installation, the Ashford team proactively purchased a second motor identical to the one installed two years later.

"The new stability of the station has been remarkable. Four years ago, it was at very high risk, and now it simply runs in the background and receives routine maintenance. Thanks to WEG's involvement," Iggy concluded.

WEG has high-voltage motors installed in several major water treatment plants in the UK, and with this further major supply, the company reinforces its vast experience in manufacturing large motors for water applications.