May 2021

34 n MOTORS May 2021 www.drivesncontrols.com Mega-pump upgrade satisfies Londoners’ growing thirst T he Thames water ring main – previously known as the London water ring main – plays a critical role in supplying drinking water in the capital. Originally built between 1988 and 1993, the structure forms a 80km-long ring of 2.54m-diameter concrete pipe primarily used to transfer drinking water from treatment plants in the Thames and Lea basins to consumers in the city. The main ring runs 10-65m below ground level and passes through 21 wells that serve as supply, storage and pumping stations. One of these pumping stations is Battersea shaft – a 30m-deep vertical shaft containing six pumps that supply several parts of London with drinking water. However, increasing development in the capital has made it necessary to remodel and replan the network to meet the growing demand. Predictions suggested that without upgrading the Battersea facility, there would be a significant shortage of drinking water capacity in a matter of years. The station needed additional pumping capacity and that, in turn, necessitated new pumps, motors and variable-speed drives (VSDs). It was decided to replace one of the 30 mega-litre per day vertical turbine pumps with a new 45 mega-litre per day alternative. This was the maximum size that could be accommodated because the site’s physical limitations. The challenge was to replace the pump without disrupting the supply of drinking water to the capital. This requirement had a major influence on the design and construction of the pumping system, and the project as a whole. It was decided that only the pump being replaced would be taken offline, allowing the rest of the system to continue operating as normal. However, to achieve this, detailed planning of the pump’s removal, re- installation and commissioning was essential. Working together, the pump supplier Bedford Pumps and the motor supplier WEG decided that best option for the installation would be a water-cooled motor. They chose a 450kW water-cooled induction motor from WEG’s Master Line range, which can be customised easily, making the motors interchangeable with existing machines. The previous pump and motor had extensive monitoring and fault detection instrumentation, so similar functions were specified for the new pump. In addition, because replacing any wiring between the electrical equipment and the pump in the awkward location would be invasive and would require downtime, the new instrumentation had to be compatible with the existing wiring, further complicating the motor selection and installation processes. The new pump installation was completed in January 2020, and the system is now in full service. Designing the equipment to work with existing infrastructure, together with detailed planning of the construction process, reduced the installation period and avoided the need for any pump outages. WEG had promised that the new pump motor would achieve an efficiency of at least 96%. After the new system had been installed, the motor’s efficiency was tested and was found to exceed this figure comfortably. n A pumping station in the shadow of London’s iconic Battersea power station has been upgraded to meet the growing demand for water from the capital’s thirsty residents. A massive pump and motor had to be replaced without disrupting the water supply. Lowering the new pump into position at the Battersea pumping station Out with old motor (left) and in with the new (right)