The trend toward ever increasing interconnection and digitalization is also unmistakable in the water and wastewater treatment industry. This trend goes hand in hand with an increase in the number of electronic components that must be connected from the field level to the control level in subsections that are sometimes far apart. When modernizing its water supply, the city of Schieder-Schwalenberg also updated its surge protection concept to reflect the state of the art.
To ensure that water is reliably delivered to consumers and is of drinking-water quality whenever possible, failsafe technology must be used. The surge protection concept plays a key role in the design. To be able to continuously supply the residents of Schieder-Schwalenberg in East Westphalia with fresh water, the city has modernized the water supply step by step in recent years. The focus was on failsafe performance.
Protection concept modernised
“In the past, we often had to struggle with the negative impact of lightning and overvoltages,” explained Ulrich Wicke, Head of Automation Technology in the building yard of the city of Schieder-Schwalenberg. “Several years ago, we decided to use surge protective devices from Phoenix Contact. They helped us significantly reduce water supply interference and failures.”
Water treatment plant modernization was planned to go hand in hand with updating the surge protection concept. The first priority was interconnecting the electronic components, which were often located far away from each other, and communicate status messages via the remote signaling network. At the Hannover Messe in 2018, Wicke was drawn to the new TERMITRAB complete series at the Phoenix Contact booth. “With the compact protective devices for sensor and actuator cables, we wanted to save lots of space,” recalled Wicke. “Due to the protective device’s integrated monitoring function, we also wanted to reduce the time and effort involved with service and maintenance.” Two companies from the region supported Wicke in his work to modernize the water treatment plants: Herrndörfer and Partner, the engineering office from Bad Oeynhausen and Riegler, the automation company from Lemgo.
Everything watertight
Numerous sensor and actuators – and all other signal-processing devices – must be integrated into a protection concept as protection against the risk of lightning. For the water supply in Schieder-Schwalenberg, the following cables entering from the outside were secured with surge protection:
- Power supply
- Sensor/actuator cables
- Telephone connection via SHDSL and ADSL
The type 1+2 [2] Flashtrab SEC pluggable lightning and surge protective device combination was selected for the power supply. With a lightning current carrying capability of 100,000 A (10/350), this protection can withstand any storm. “To intercept overvoltages from elevated tanks, we also installed these surge protective devices on the line to the elevated tanks,” explained Wicke. “With this line, thanks to the integrated remote signaling function of the SEC family that forwards the status of the protective devices, we can also monitor the state of the protective device remotely.”
All sensor and actuator cables were equipped with the compact components from the TERMITRAB complete product family. In the city of Schieder-Schwalenberg, they decided in favor of this product series because the products are only 6 mm wide and enable space savings in the control cabinet. Because the components are pluggable, they can be conveniently – and inexpensively – replaced in the event of overload. The status of the protective devices can be easily queried via a remote signaling unit in this application as well.
The remote signaling function is also easy to install. It is sufficient to supply the two-part remote signaling unit with electricity, because the protective devices themselves do not require any auxiliary power. “After snapping into place at the beginning and end of the protective device strip, the unit was immediately ready for operation,” explained Wicke. “We did not need any elaborate programming, either.”
Surge protection at a glance
The additional MCR lines that led to the elevated tanks were equipped with components from the COMTRAB modular product family. A TC extender – a modem featuring integrated surge protection – was used for the SHDSL connection. For the ADSL connection, the TAE-Trab was used – a surface-mounted surge protective device for analog and digital telecommunications interfaces.
With these components and measures, overvoltages are intercepted across all lines that lead to the outside. In this way, the controller – the core of the system – cannot be damaged.
“Thanks to the remote signaling function, the status messages of all surge protective devices can be queried remotely,” said Wicke happily. “We save money, since service personnel do not always have to be on site.” To enable the status to be queried independently of the location, the elevated tanks, pumping stations, rain overflow basins, and wastewater treatment plants all communicate with each other with the help of SHDSL telecommunications cables. The SHDSL signals in turn are connected to the central Ethernet via modem. The central computer in the water treatment plant communicates with all other PLCs at the locations via Ethernet. Via the AX OPC Server communication interface, the computer continuously receives current system data. Maintenance personnel are kept up to date of the status of the protective devices through this network at all times. If a signal is issued, the protective device is replaced immediately on site. The indicator integrated into the connector enables the overloaded protective device to be identified quickly.
