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Modernization of control technology at RWE Westfalen-Weser-Ems

Regional supply to 5.5 million inhabitants

RWE Westfalen-Weser-Ems AG based in Dortmund, Germany, is the regional subsidiary of RWE Energy. RWE Westfalen-Weser-Ems supplies customers with electricity, gas, water and associated services from a single source.

The company provides a reliable supply for 5.5 million inhabitants. Over 24 TWh of electricity and around 52 TWh of gas are supplied via a power supply network covering a total length of 76,000 kilometers and a gas network covering 20,000 kilometers.

RWE Westfalen-Weser-Ems employs around 2700 people.


As the operator of the distribution network, RWE Westfalen-Weser-Ems provides cost-effective power supply to the region. The optimization of power supply constantly presents new requirements for control and automation technology.

The company used remote control technology from Siemens to modernize its 110 kV stations. Thanks to the minimal wiring involved, the use of PLC-INTERFACE solid-state relays from Phoenix Contact enabled space-saving, compact control cabinets to be used, thereby significantly reducing costs.


As part of the modernization project, Siemens Energy Automation GmbH & Co. KG were commissioned by RWE to update the 20 to 25 year old control technology in the unoccupied 110 kV stations. The AK 1703 ACP automation system from Siemens is now used. It offers comprehensive options for remote control, communication, and the connection of I/O devices for the automation of power supply networks.

The tasks performed using remote control technology include determining the operating states of switches, acquiring the instantaneous values of currents and voltages, as well as their reliable transmission to a central control room. In addition, the remote control technology has to control the system from the control room by means of commands and setpoints. PLC-INTERFACE modules from Phoenix Contact act as an interface between the system technology and the remote control technology.

When digital signals are acquired via the PLC-INTERFACE modules, signaling voltages of 220 V DC on the system side are converted to the signaling voltage of 60 V DC that is used in the remote control technology. The signaling voltages are electrically isolated from one another via PLC-INTERFACE components. In this case, the remote control technology acts as an isolating module.

Using modern remote control technology, errors are indicated and appropriate measures are determined from the information provided. As part of the growing degree of automation in unoccupied stations, PLC-INTERFACE ensures the technical and cost-effective decoupling of signaling voltages on the primary and secondary side. The modules therefore represent an important coupling element between process and remote control technology.


Through the combination of remote control system and PLC-INTERFACE, a space-saving and easy solution for monitoring and controlling processes is possible even in large distribution network stations.

With a design width of just 6.2 mm, PLC-INTERFACE offers a space saving of up to 75%. By eliminating the jumpering level, the size of the control cabinets has been reduced significantly. In addition, it is possible to save on a huge amount of wiring by also using the bridging options offered by the integrated bridge shafts. These features all contribute to a consistent reduction in costs. The structure and documentation of PLC-INTERFACE are an integral part of the remote control cabinet.

Another advantage of this integration is the system acceptance at the factory, as all secondary equipment can be tested here in its entirety. This eliminates complex wiring work on site during startup, which in turn reduces installation time and costs. Thanks to these excellent features and this positive experience, these components will also be used in future projects.

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