Industrial drives hold back flood waters

An ABB Automation Tech (Drives and Motors) product story

Edited by the Engineeringtalk editorial team Apr 22, 2008

Optimum selection of drives technology was made after considering many different solutions for this application.

Six 1250kW ABB industrial drives will be powering the UK's largest pumping station, protecting 700km2 of land in the Cambridgeshire Fens from flooding.

The new pumping station at Wiggenhall St Germans will protect more than 25,000 properties, businesses conservation sites and extensive areas of high-grade agricultural land in an area called the Middle Level.

The optimum selection of drives technology was made after considering many different solutions for this application, these included options for liquid cooled drives, medium voltage drives and step-down-up transformer solution packages.

ABB assisted the consultant and contractors at every stage to consider the capex and opex costs for each solution against the mechanical constraints imposed by the new building infrastructure.

Much of the Middle Level is below sea level following centuries of peat shrinkage and wind erosion.

The existing pumping station is over 70 years old and has been deemed to have come to the end of its operational life and to lack the capacity to meet the challenges of climate change.

The current station comprises four pump sets delivering a total capacity of about 70m3/s.

Each of the six new pump sets will be able to raise 16.66m3/s to a static head of 4.25m, giving a total capacity of 100m3/s.

This gives the new station the capacity to deal with extreme events, although in a moderate year it is expected to run no more than up to three pumps at a time under normal conditions.

A system of rotation will therefore be introduced to ensure that the pumps get an equal amount of use.

The ABB industrial drives will adjust the pumps to suit a wide range of flows.

Each pump will operate to match the actual flow demand and can respond immediately whenever circumstances change.

The new pumps will also provide quicker response at start-up as they do not need priming, as is the case with the existing units.

The station will pump water from the Middle Level into the tidal River Great Ouse.

Upstream conditions are relatively stable, but the discharge head can vary between 0.5m and 8.0m above the suction level, depending on the tide.

It is also possible for there to be no discharge head at all during extreme low tides.

The pump impeller and variable speed drive control have been carefully designed to prevent cavitation occurring at the extremes of high or low head.

The ABB drives are expected to be installed by mid-2009 and the site will be operational by the March 2010.

The GBP 38 million pumping station will be owned and operated by the Middle Level Commissioners and is being built with the help of a 45% grant from the Department for Environment, Food and Rural Affairs (DEFRA).

Atkins is the lead consultant responsible for the project.

Once complete, this modern station should provide security from flooding throughout its 75-year working life.