www.worldpumps.com WORLD PUMPS October 200520

a p p l i c a t i o n s w a t e r s u p p l y

In any wastewater pumping station, the pumps arehigh-energy users – and managing energy costs isan ongoing challenge made even more importantsince the introduction of the Climate Change Levy.Energy unit costs have differential rates according tothe time of day and season, and can increase overallcosts by up to 15%.

During high cost periods, additional charges basedupon transmission charges (triads) can occur duringwhich time users are notified to reduce energyconsumption. Notification can come at short notice– even within a few hours of the period – requiringquick adjustments to avoid added costs.

As part of an initiative to reduce overall operatingcosts, South West Water sought strategies to saveenergy and manage escalating energy costs andcalled upon Siemens to help.

Following a trial with one unit over a six monthperiod, the region installed eight EnviroRanger ERS500 controllers in seven pumping stations dedicatedto saving energy costs as well as control.

How the pump controllers work

Echomax ultrasonic transducers send reliable levelmeasurement signals to the EnviroRanger, whichprocesses and logs the information. Because theEnviroranger device features Sonic Intelligence

advanced echo processing technology, it is capableof delivering reliable, repeatable measurement,Siemens says.

Thirty EnviroRangers installed across the region areconnected to the SWW telemetry network usingbuilt-in Modbus protocols via Serck PX24 telemetryoutstations. This gives remote monitoring andcontrol capabilities from the central control room.

Previously, each station required a levelmeasurement system, programmable logiccontroller, and remote terminal unit for telemetry.EnviroRangers can eliminate the need for multiplesystems because it provides all the functionalityrequired to control pumps, collect data, andcommunicate over the network. A real-time pumpcontrol avoids pumping during the peak costperiods.

This economy pumping regime pumps the welldown to its lowest level before the premium rateperiod, and then maintains a higher level during thepeak tariff period.

The EnviroRangers also incorporate a stormdetection feature which can detect high rates ofinflow and automatically switches back to normalpumping in a storm. This can help avoid overflows,ensure compliance with environmental regulationsand minimise energy use in peak tariff periods.

EnviroRanger also monitors pump efficiency toremove a failed pump from operation, switch to ahealthy pump, and flag a maintenance alarm. It alsoreduces the need for routine manual siteinspections, saving staff time and freeing them forother tasks.

“The key to achieving operating cost reductions is touse all the features of the EnviroRanger,” says RobinLennox, ICA Specialist with South West Water. “Weestimate we have cut our energy costs by almost10% at certain sites. We have had a rapid return onour investment over the first year.”

Siemens helps manageUK energy costsSouth West Water, based in the UK, holds the water and sewerage appointments forthe South West of England – an area servicing 1.5 million residents. It worked withSiemens Automation and Drives Process Instrumentation and Analytics to test andrefine the EnviroRanger, a new state-of-the art pump controller to help manageenergy costs.

South West Water’s wastewaterpumping station based in the southwest of the UK.