Konstanz’s AEG control system has been in operation since 1989, and its obsolescent disadvantages are beginning to show. This disadvantage has tended to be obvious, in the long run, the supply of spare parts of the system will not be guaranteed. A project has been launched to implement the new system, which aims to achieve control and monitoring of all equipment in the waterworks. Fully automated operations are inevitable, and the safety of the water supply must at least be maintained, if not improved. Wolfgang Fettke, business unit manager of Konstanz Waterworks, and the technical team led by Wolfgang Treib have come up with a state-of-the-art solution. “Our decision to use the Beckhoff system has given us great value for money,” says Wolfgang Treib.

The easy monitoring and documentation of production data made possible by new control technologies was not one of our original goals. For the people in charge of the project, the openness of the system is important. The following instructions were given to the contractor, Cegelec: Hardware selection and communication protocols could not be dependent on a specific manufacturer. The meticulous water treatment waterworks supply water to 87,000 people in Konstanz and the surrounding area. Up to 50,000 m3 of drinking water is supplied every day. Current supply averages 14,000 m³ per day. As with the rest of the population, this trend is declining as the people of Konstanz use drinking water more efficiently. Water is pumped up from a depth of 40m (under the plagiothermocline or thermocline). At this depth, the water is very clean and uncontaminated by surface pollution. The Konstanz waterworks, which supplies water at three different elevations and at different pressures.

3BSE018741R15

3BSE018741R15

3BSE018741R15

Raw water is drawn from Lake Konstanz through a 700m long pipeline; The first step is water treatment, where raw water is fed to a 23 μm mesh width microfilter. The second step is ozone sterilization, which is produced directly in the waterworks through the surrounding air. The third and final step is to use a sand filter, which was upgraded to a multilayer filter in 2005.
Although the quality of the water from Lake Constanz is very high, we improved the filtration by adding a small amount of ferric chloride (III), 200 times less than the usual amount. Modular bus terminal modules replace expensive I/O cards. It is easier and more cost-effective to replace only factory “smart equipment”. That was really our initial intention. This transition is non-critical, and it’s easy to reuse an older CPU. “However, because we wanted a trend-setting solution, every requirement pointed to an open system construction, and we found this solution in the open modular bus terminal module technology,” says Wolfgang Treib, commenting on the specification requirements.

“We believed, and certainly still believe, that this was the most economical solution.” Wolfgang Treib confirms this view based on practical experience: “Twenty years ago, the cost of buying an I/O card could now buy multiple industrial PCS, including bus terminal modules.” Having several bus terminal modules in stock for maintenance and repair does not require much capital.
One of the key requirements of the new automation system is that patented components and serial bus protocols cannot be used. “The primary goal of the new control system type and structure is to improve equipment utilization. “The decision to use industrial PC (IPC) systems gives us a lot of freedom in the design of our applications, and the current architecture makes it very easy to connect to subsystems,” WolfgangFettke said. “The decision to use Beckhoff systems gives us a clear benefit.