Testing of 50 Hz train charging in Saxony

Despite all the efforts to electrify the German rail network, many regional lines will remain without catenary in the future, as this investment is not worthwhile everywhere. That's why SRCC (Smart Rail Connectivity Campus) of Annaberg-Buchholz has developed a system for charging battery trains. The VMS (Verkehrsverbund Mittelsachsen) is also involved in the project, because in the future the Coradia Contintenal BEMUs of this transport association are to run right up to Annaberg-Buchholz on the Erzgebirgsbahn. 

However, 15 kV 16.7 Hz is used for recharging from the overhead line, which is not available outside the electrified sections. In such cases, power is available from the 10 kV or 20 kV national grid at 50 Hz, but this must be adapted. To this end, the Rail Power Systems (RPS) consortium was formed, consisting of DB Energie, DB Regionetz Infrastruktur, F&S Prozessautomation, Rail Power Systems, SRCC, TU Dresden and VMS. This consortium has built a charging station that can convert and provide a national voltage to 15 kV while maintaining a frequency of 50 Hz. Alstom then adapted the battery trains to this type of charging on behalf of VMS.

Since June this year, a 23-tonne container has been standing at Annaberg-Buchholz Süd station, which can be transported by road and from which a newly built short section of overhead line is fed. This can then be used to recharge the vehicle batteries when the pantograph is raised, as shown in the photo of 1440 402, which arrived in battery mode from Flöha (east of Chemnitz), where it left the catenary.

Mathias Korda, Managing Director of VMS: adds: "The RPS consortium still has a lot of work to do to make this charging technology ready for batch production. However, a decisive step has been taken to enable battery trains to be deployed even onlines without catenary - currently only around 60 % of the German rail network is electrified." 

For regular operation, the platform (two trakcs) at Annaberg-Buchholz Süd station will still need to be equipped with a longer overhead line so that trains can be charged during normal stops. The charging station is also available for testing by other vehicle manufacturers before it is ready for commercial operation.

Deliveries of the Class 1440.4 BEMUs are scheduled to take place in summer 2024, while drivers will need to be trained and familiarised with the special energy management system. In parallel, maintenance logistics will also be set up. Initially, the units will gradually appear on the RE 6 Chemnitz - Leipzig line, where they are to start regular operation by December 2024 (with the possibility of recharging from the overhead line at both end stations).

Once a stable timetable is in place here, the 1440.4s will run as far as Annaberg-Buchholz during off-peak hours; a specific date has not yet been set. The idea of sending BEMUs to Annaberg in the day range times is about a year old. Originally, the BEMUs were only supposed to run between Chemnitz and Leipzig. At present, the Erzgebirgsbahn uses Desiro VT 642 DMUs, which will continue to operate there in the future, too. The BEMUs will only serve as a supplement.