The Geiseltalsee, the largest man-made lake in Germany, is located in the ZWAG district around Braunsbedra. Brown coal was mined in Geiseltal until 1995 and it is now the site of a recreational area.
In order to ensure that the water supply in the region is not negatively impacted, all accumulated wastewater is fed into the ZWAG wastewater treatment plant.
As part of modernization measures, the team at ZWAG were looking for a new solution for three wastewater pumping stations. The Stöbnitzer Mitte pumping station pumps the wastewater directly into the watercourse leading to the wastewater treatment plant. In contrast, the two new pumping stations at Geiseltalsee – the Strand Mücheln main pumping station and the Strand Mücheln pumping station – alternate between supplying the watercourse. This is more useful in terms of energy than a cascade design for the infeed.
A comprehensive solution was required, i.e., more was needed than just individual components from various different manufacturers. Additional requirements included protection against damage caused by surge voltages and operational availability ensured by a modern uninterruptible power supply. In light of this, the optimally coordinated concept from Krohne Messtechnik and Phoenix Contact made quite an impression. The concept is based on function blocks from the Waterworx water process library which were developed jointly by both companies. The blocks can be used to easily integrate the measuring technology into the automation and control technology.
Various automation technology tasks have been implemented based on this setup. This includes incorporating the pumping stations into the control system of the wastewater treatment plant using mobile communication and SHDSL technology and integrating field devices, such as the Optiflux 2050 W flowmeter from Krohne, as well as other measuring and drive technology components.
The PSI-MODEM-SHDSL/ETH industrial permanent line modem can be used to network serial devices via broadband using in-house copper cables. The SHDSL technology enables data rates of up to 30 Mbps. The SHDSL modem can be used to establish point-to-point connections, path redundancy as well as line and star topologies. This means that the modems automatically determine the SHDSL rate between themselves, thereby eliminating the need for configuration via DIP switches.
The assignment of an IP address and client/server configuration is not required. An integrated logbook and alarm outputs simplify servicing on site.
Mobile communication replaces lack of cable-based connections
Where in-house lines or the public telephone network are not available, the high-performance 3G router from the PSI modem product range is used to forward data wirelessly to the control system. The pumping stations are integrated into the IP network via a UMTS/HSPA connection. If this connection does not work, the 3G router automatically switches to GPRS/EDGE. The built-in firewall and VPN support protect against unauthorized access.
The data link and quality of the mobile network are also monitored. If the situation worsens, the 3G modem sends a corresponding message or re-establishes the mobile network connection. Six configurable switching inputs allow SMS messages or e-mail to be sent independently, to multiple recipients. The four integrated switching outputs can be actuated via password-protected SMS to check the system state remotely and to switch functions.
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