WATER INDUSTRY n The pump motors started to experience faults. The motor insulation was degrading so badly that it resulted in a short-circuit between two phases – an issue which could cause the motor to fail. When this happened, the motor had to be taken out of service and rewound, losing some of its efficiency (unless the work was carried out to strict guidelines set out by the Association of Electrical & Mechanical Trades). Some of the motors were rewound three or four times. After a motor had been refurbished, Thames Water engineers expected to get further 5-10 years of operating life out of them. But the machines were failing within a couple of years of the work being done. The utility therefore approached three of its framework suppliers to provide replacement motors that would tackle the high failure rates. According to Ashford’s engineers, one of the key reasons why WEG stood out was they offered a turnkey solution, instead of simply acting as supplier. For Ashford Common’s small engineering and maintenance team, covering a big works with many assets, it wasn’t an option to manage the project internally. The maintenance team is usually busy on repairs and reactive work, so it welcomed an offer by WEG to do all of the troubleshooting and to ensure that the right equipment and the right people were on site. As a commissioning partner, Thames Water chose BGEN – previously known as Boulting Group – to provide the on-site installation and project management in collaboration with WEG. Bespoke replacements WEG engineers visited the site on several occasions, examined the motors, reviewed the setup and advised Thames Water to go for bespoke high-performance 600kW, 415V, 10pole flange-mounted motors. These rugged, reliable motors from WEG’s HGF line are energy-efficient, with low maintenance costs, and are ideal for tough environments, such as water industry applications. The way that the huge power cables feed the pump motors required out-of-the-box thinking. There are nine connectors on the power side and about 24 on the control side. The cables – each about 2m tall – are stiff and not easy to manipulate due to their large size. Instead of having to cut the cables and then re-terminate and gland them – which would have involved messy, difficult and physical work – WEG’s engineers suggested manufacturing a bespoke terminal box so that the glands where the cable goes through the metal on the junction box could be kept the same. The purpose-made connection box allowed the existing plate to be married up. This required a lot of accurate measurements because the cables are a set length, and each one was slightly different. The lead time for supplying the first bespoke motor was around six months. By the time the motor was ready to be shipped from WEG’s factory in Brazil, Brexit was starting to have an impact in terms of dealing with imports and delays. The Ashford Common plant desperately needed the motor because one motor had already failed, and Thames Water needed resilience as it entered the summer period. To ensure delivery, WEG organised two separate shipping companies, in different locations in the UK where, the delivery vessel could dock, depending on the weather conditions. Intermediate companies were lined up to handle the imports and transport the motor to site. The first motor was replaced in 2019. It proved so reliable that Thames Water bought a second identical machine, which was installed in 2021. “With the first motor, our team built the motor with the junction box to suit and that significantly minimised the time on site,” recalls Gustavo Da Silva, WEG’s sales and development manager for high-voltage systems in Europe and the Middle East. “When you’re dealing with something of this size it is these small details that make the difference. With the second motor, there were a few alterations in terms of physically how the cables were mounted. Additionally, guarding was retrofitted to the first motor on-site. The second time around, this was done in the WEG factory instead.” Three months before the second motor was due to be delivered, another old motor failed. Since then, however, the Ashford site hasn’t experienced any further breakdowns. “The new-found stability of the station has been noticeable,” reports Iggy Pont Lezica, operations technical lead at the treatment works. “Four years ago, it was at the highest risk by far and now it just works away in the background and receives routine maintenance. There are so many other aspects for the maintenance team to look at, we expect the equipment that simply shifts the water from one place to another to work effectively and reliably. Now, thanks to WEG’s involvement, it does.” A significant amount of work was done between 2018 to 2020, including replacing five of the drives and proactively conducting refurbishments on the pumps. The last pump is currently being refurbished and two further motors will be replaced this year and next. n
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