Since 2015




IEC 60870-5-104

The Stuttgarter Straßenbahnen AG (SSB) is one of the largest and most modern public transport companies in Germany and has received several awards for its services in recent years. The SSB ensures mobility in the state capital of Stuttgart, thereby ensuring the functioning of the city and the quality of life of its inhabitants.


A good 500 buses and trains and around 3,000 employees work every day. Almost 970,000 people live in the traffic area. Every work day, nearly 600,000 people use one or more of the 72 SSB lines

Since 1986, we have installed telecontrol systems for switching, measuring and monitoring operations in the 10 kV traction substations. To date, about 100 telecontrol systems are in use, which essentially fulfil the following tasks:

  • Switching and monitoring the driving voltage, low voltage, tram stop lighting, tunnel lighting and point heating
  • Control of escalators, roller shutters, fire doors and ventilation systems
  • Monitoring fault voltages, temperatures, error messages


In 2015, the decision was made to modernise the ageing telecontrol equipment. Initially, 60 substations in the substations (UW) were to be renewed and a further 20, mainly smaller ones, to be constructed at the stops. As part of a tender, the net-line BCU-50 and the smaller net-line FW-5 system prevailed over the usual competitors. With a complete solution, SAE offered everything from a single source, including the installation of switchgear cabinets with all the assembly, installation and seamless on-site integration in the substations. The execution was carried out by our experienced plant engineering, with the support of SSB personnel. The customer only wanted to develop the system configuration of the telecontrol stations himself. For this purpose, SAE has an innovative and very convenient setIT parametrisation software. With just a few clicks, the system can be quickly and easily configured and extensive diagnostic functions can be set.

With the BCU-50 we have delivered a very robust, modular bay station controller with high functionality and reliability, which perfectly meets the requirements in the traction substations. Depending on the size, several BCU-50 racks with 19″ mounting frames were required for installation in the switchgear cabinet, which are interconnected via integrated Ethernet switches. The whole system is optimised with a special BCU rack, through which all connection cables can be routed cleanly to the rear and intercepted in flexible cable hoses. FW-5 telecontrol systems will also soon be used in the technology cabinets of the stops. They are supposed to take over the switching of the stop light, in case the network connection gets interrupted. For this purpose, a PLC program specially written by the SSB is stored in the FW-5. For another project, a so-called TBUS remote I/O was used. This TBUS extension provides a simple and cost-effective way to place several FW-5 expansion modules in different switch panels, which are then connected to the FW-5 base unit via a patch cable only. This can be bridged up to 1,000m.

Nationwide connected

The telecontrol systems are distributed over the entire urban area and connected via so-called HiPER rings (high-availability fibre optic networks) via Ethernet LAN TCP/IP to perform switching operations from the control centre (IDS) as well as from the network control centre (KISTERS). The TCP/IP-based telecontrol protocol IEC 60870-5-104 is used throughout.
For the BCU-50 as well as for the FW-5, there is a large selection of modules for individual expansion, as well as numerous communication options that allow the connection of control systems and protection devices by means of different protocols and interfaces, regardless of the manufacturer.

Good feedback

The SSB commented on our efforts to offer solutions that are customer-oriented:
“Sophisticated functionality, practical know-how, user-friendly configuration software, optimal and cost-efficient solutions, a wide range of communication options, high IT security according to BDEW whitepaper.”
Thomas Schulz, SSB