For almost two decades Liebherr-Transportation Systems has been a supplier of heating ventilation air conditioning (HVAC) systems for suburban double deck coaches built by Bombardier and operated by German National Railways Deutsche Bahn (DB). Since 1997 Liebherr provides the air conditioning system and the on-board power supply for the double-deck coaches.
In 2003, DB decided to launch a new generation of double deckers which should be equipped with the latest generation of on-board power supply and control systems. Liebherr was selected again for the entire system comprising both HVAC and power supply.
Similar types of coaches have been delivered to other railway operators such as Danish State Railways (DSB), Railways of German Federal Land Niedersachsen (LNVG) or Railways of Luxembourg (CFL). In total, Liebherr equipped more than 2,100 coaches with the complete air conditioning system – almost 1,300 of them were dedicated to DB. In addition, Liebherr retrofitted 49 DB double deck coaches of the first generation with HVAC units and the latest generation of power supply inverters including CAN Bus controllers.
Liebherr-Transportation Systems has developed an innovative, modular, highly integrated power air conditioning (PoAC) power supply system for the air-conditioning units. Liebherr supplies a wide range of frequency converters in the insulated gate bipolar transistor (IGBT) technique for supplying the air-conditioners with all the current voltage levels in the railway vehicles. The frequency converters meet all applicable railway standards and can be used for different voltages / frequencies, their control proceeds through the bus connection. The electric connections of these instruments are provided with plugs that meet railway standards.
The double decker system supplied by Liebherr:
- Provides for a compact, integrated air conditioning system, including a tailor-made, cost and energy-efficient drive system for fans and compressors as well as a powerful battery charger
- Allows high efficiency when generating power supplies from the high voltage train power bus bar
- Offers a “plug-&-play” solution
- Utilises the vehicle’s existing electrical interfaces
- Has connections to the train control and monitoring system by means of standardized interfaces (e.g. MVB or CAN)
- Uses intelligent diagnostic signalling and monitoring routines to increase reliability and hence availability
- Is built in partial redundancy. 50 % of the output power are still available even if one of the supply fan inverter fails
- Costs less than standard solutions with separate units once all associated costs for the standard solution are considered
- Offers reduced weight and requires less space, facilitating air conditioning concepts with increased redundancy