VSD provides efficient solution
December 1st 2005 Since the implementation of a new VSD controlled system, Nebraska City Utilities no longer needs 24-hour manual pressure adjustment durting water tower maintenance. The facility can now provide reliable water pressure throughout the Nebraska City area, even when the water tower is out for maintenance. A new pumping system with Danfoss VLT 8000 AQUA VSD motor control resolved the pressure problems and also brought water quality up to latest public health regulations.
"It's a challenge to make sure all community residents will have water whenever they turn on their tap for a drink or get under the shower," says Dean Hauptman superintentent of Nebraska City Utilities Water Treatment Plant. "When something affects the pressure, as when the water tower is down, we had to be here around the clock opening and closing valves."
The city also had to meet new water quality standards. It get its water from groundwater sources and the treatment facility had to increae the time the water is exposed to chlorine. The high-flow conditions did not allow this. There was the added problem that the water tower level was maintained exclusively by on/off control. As a result, there were pressure fluctuations and a lot of water loss due to leaks, which meant big nonrevenue water costs.
The solution was a new highservice pump equipped with VLT 8000 AQUA drive with AHF harmonic filtration, and VLT soft starter MCD 3000. Now, instead of the four pumps in the old system, the new system uses just one highservice pump. Electronic control is now much more energy efficient than valve control. The frequency converter constantly matches the speed of the pump to the pressure demand to keep the pump operating at its highest efficiency point for much less energy use.
Improved water flow and overall system efficiency was followed by tighter pressure set-point control, reduced non-revenue water costs, lowered customer complaints about pressure fluctuations and a significantly decreased plant energy bill. More articles from Danfoss Limited: | 
