|Translohr tram in L’Aquila, Italy|
Saft has developed an integrated NiMH battery system to support a different twist on hybrid trams: trams that can switch the source of traction power between overhead catenaries and on-board batteries.
Trams—urban light rail vehicles—come in bi-current versions that are able to use the different current flow from city tram lines as well as electrified rail lines (e.g., 600/750 Volt DC and 15 kV 16 2/3 Hz AC) as well as diesel-hybrid versions that rely on diesel traction for operation on non-electrified tracks (such as in the suburbs).
But the city of Nice, France, which uses catenary wires on its new tramway system, wanted to keep its two historic town squares (Place Masséna and Place Garibaldi) clear of the overhead wires, and didn’t have sufficient need for a full diesel-electric system.
Alstom, the tram maker, thus needed an onboard traction battery capable of providing sufficient autonomous power for travel over those sections of track where the catenaries are not available—approximately 500 meters for each autonomous section. The system also had to be compact enough for installation in the vehicle roof.
Alstom placed a €2-million (US$2.4-million) order earlier this year with Saft for NiMH integrated traction battery systems for the CITADIS trams currently under construction for the city of Nice.
Now Lohr Industries is also interested in the Saft NiMH batteries for its Translohr rubber-wheeled tram systems in some Italian cities for the same reason: keeping medieval city centers clear of catenaries.
The 576V Saft NiMH battery system provides 80 kWh of continuous power. Each battery system incorporates an active cooling device and battery management control (BMC) for monitoring of temperature, voltage and charging conditions. The whole unit is supplied ready to plug and play in a custom built tray complete with power and communication capabilities and all necessary safety features.
In addition to the traction batteries, Saft is also supplying 24V on-board MATRICS MRX rechargeable nickel-cadmium batteries to provide backup support for electrical systems such as doors and communications.