Delays and canceled trains are not something the Berlin S-Bahn (suburban railway system) can afford. The trains transport close to 1.4 million people every day. One of the most popular and busiest lines is the ring line. The series 480 trains have been running on one-third of the suburban railway system since the early 90s. DB Regio commissioned ABB to find a solution to keep using robust and cost-efficient trains for another 8 to 10 years after their usage period ended in 2017. This was part of a comprehensive modernization program, which included updating the power electronics.
A total of 140 drive containers of 70 so-called quarter trains (twin units of the S-Bahn Berlin) were equipped with state-of-the-art IGBT-Technology, while simultaneously connecting the traction control system to the existing vehicle control system. Only the drive technology was modernized while all mechanical, electrical, and signaling interfaces were kept the same, making this project unique when it comes to its complexity and technical challenges.
Solutions for the challenges of local and long-distance transport
ABB developed a new and innovative approach to modernize S-Bahn trains in Berlin. Worn and broken parts of the power electronics are renewed or repaired with the same functionality according to the principle of Plug-And-Play. This means the trains are being modernized step by step instead of a complete reconstruction. This lighthouse project was carried out in close cooperation between the Traction business units in Switzerland and Germany. The engineering, module, and component production as well as the refurbishment of the drive container for the first vehicle took place in Switzerland. ABB Germany was responsible for the drive containers’ serial refurbishment.
Retrofit process (Source: Berlin S-Bahn, Germany) 
Retrofit process (Source: Berlin S-Bahn, Germany) 
Retrofit process (Source: Berlin S-Bahn, Germany)
Modular retrofit drive technology
The robust drive module supplies the drive motors of two bogies in parallel, but independent of each other. All existing power and control cables remain in the vehicle. Interface electronics were developed to connect the new IGBT inverters to the existing vehicle control system based on ABB’s scalable AC500 PLC platform. ABB also renewed the auxiliary converters and refurbished the existing battery charges.
Before delivery and installation, ABB put all components through their paces for quality assurance. The test phase consisted of a series of different individual tests. Among them, an electrical isolation test and a dielectric withstand test, as well as a clocking of the core module with the help of a test unit. Functional testing checked whether all contacts were in the right place and whether the links were working. The first conversion kits could thus be delivered just five months after commissioning.
More reliable, easier to maintain and energy-saving
As the modular design is maintenance-friendly and equipped with standardized power modules, it can guarantee high spare parts availability and minimizes vehicle operating costs.
The approach consistently replaces only the obsolete and no longer functionally required parts, or parts that were already integrated into standard PEBBs (Power Electronic Building Blocks). By installing the new components in the existing traction container, the given vehicle structure is used without any changes on the mechanical side.
Compared to a classic complete retrofit, the execution is therefore faster. Furthermore, less material is replaced and more can be reused, which has a positive effect on both cost and the environment.
The new components are also significantly smaller, improving the overall weight balance of the vehicle. By using the latest IGBT technology, switching losses can also be significantly reduced. This ultimately leads to higher efficiency compared to the old thyristor technology. The retrofit thus not only extends service life but also reduces the S-Bahn train’s energy consumption.
Ready for at least another eight to ten years of operation.
For the Berlin S-Bahn, the cooperation has paid off in every aspect: With ABB, the series 480 fleet was modernized efficiently and in an energy-saving manner, securing ongoing service on Berlin’s rails for at least another eight to ten years. The new drive module comes with a diagnostic tool, which contains an advanced self-diagnostic function.
This allows service and lifecycle engineers to access the inverter's diagnostic data (signals, parameters, incidents, and status data) remotely at any time and without being directly connected to the maintenance computer on the control platform's Ethernet network. Faster, more reliable, and safer remote diagnostic data access leads to shorter repair times and lower maintenance costs. This quickly offsets any initial investment in remote access infrastructure.
