72072 Tübingen


From 2008 to the present


net-line FW-5, net-line FW-50, GPRS modem/Router, InSyS MoRoS, Siemens SJ62 protective equipment


IEC 60870-5-101, IEC 60870-5-103, IEC 60870-5-104, Modbus-RTU

Stadtwerke Tübingen GmbH has been providing electricity, natural gas, drinking water and heat to households and businesses in the city and region for 150 years. It has been generating power from renewable energy sources with several hydro-electric power stations for more than 100 years. By 2020, the public utility is looking to cover 50% of its Tübingen power revenue with ecological power generation. Hydro power, solar radiant energy and biomass are used mainly in the region around Tübingen. Wind power is to be established regionally in the future however.


2008 saw us receive from the Tübingen public utilities a 3-year frame agreement for the supply of 10 net-line FW-50 systems – because the intention was to upgrade all remote control systems in transformer stations and control stations (110 kV, 20 kV) to a FW-50 system. Special DSO cards with checkback function had to be used to monitor the switching operations and a protective equipment link via IEC 60870-5-103 was required in part. The BTC control centre link was to be realised via IEC 60870-5-104.
Before the public utility opted for SAE, several system suppliers were subjected to close inspection. Ultimately it was not only the price but also the configuration capability using a USB memory stick that were the crucial criteria. Personnel are to this day grateful for how this simplifies work. Start-up times are shortened considerably as a result.

In 2012, the public utility again commissioned us to supply 25 EEG boxes in order to access the respective supply wattage for installations with an installed capacity greater than 100 kW and to reduce the system power via remote control. The swt-EEG-Box was designed specially for deployment within the network area of swt (Stadtwerke Tübingen). It provides a guarantee of communication with the grid controller, required in accordance with § 6 EEG 2012, in the control centre of swt.
The swt-EEG-Box comprises a SAE net-line FW-5-BT telecontrol system plus device configuration, a USV system including temperature sensor, a battery module and an InSyS MoRoS Pro GPRS modem with external antenna. The components are located in an enclosed housing.
The connection to the BTC control centre is established via the InSyS MoRoS GPRS modem with an IPSec-secured tunnel over the internet. This guarantees that communication is protected against spyware and manipulation scenarios.
Back then, swt wanted a system that can be used in the renewable energies area and in local network automation. Our FW-5 system leaves nothing to be desired here in satisfying the requirements in these application areas. For quicker fault localisation, additional intelligent components can be used, such as short-circuit and earth fault direction indicators or protective equipment from different manufacturers. Protocols such as Modbus-RTU and IEC 60870-5-103 are available for this.
swt opted for us after successful trial operation. This therefore means we have another satisfied customer in swt – for whom we would like to assume a supportive role in the future in realising its objectives.