Optimum plant availability is a key requirement in the water industry, in both wastewater purification and drinking water treatment plants. The Wupperverband, a large water authority in Germany, operates 14 reservoirs and 11 sewage treatment plants, among many other facilities. As part of a modernization scheme, the Wupperverband was seeking to update its Marienheide sewage treatment plant with state-of-the-art automation technology to ensure high reliability in data communications and thus high plant availability.
As the plant had already used a PROFINET-based control system successfully for several years, the Wupperverband decided to add PROFINET communications at field level. Approximately 20 PROFINET-enabled electric valve actuators were therefore installed in the course of the plant update.
The electric valve actuators (AUMA) are equipped with an integral PROFINET interface which supports PROFINET’s built-in redundancy concept, the Media Redundancy Protocol (MRP). The interface incorporates a switch function with two physically separate Ethernet ports that provide two distinct communication channels to the host controller. If one port fails, communication continues automatically via the second port. All actuators therefore remain accessible even if the communication path is interrupted at one point on the ring.
At the Marienheide sewage treatment plant, the actuators were installed in a ring topology and connected to the DCS via an intelligent switch. During installation, the actuators were first tested in an “island” mode before being brought stepwise into live operation.
“We expect high communication reliability due to the consistent use of Proﬁnet at both control system and field level,” explains Dirk Gengnagel, Group Leader Engineering and Organization in the Urban Water Management division of the Wupperverband. “Data and commands can be directly exchanged without any conversion; and Profinet’s ‘integral redundancy’ function provides additional safety for plant availability.”
Several aspects make this plant update important and future-oriented. Using PROFINET at both control and field level, in combination with built-in redundancy, provides the best possible communication stability and hence increased plant availability. In addition, PROFINET offers high potential for preventive maintenance: the actuators’ internal diagnostic information can be easily accessed using an integral web browser or through an FDI (Field Device Integration) package, to mention just some features. Seen in this way, the Marienheide sewage treatment plant is now fully prepared for reliable and efficient operation in the future.