Energy saving on tramlines

Summary

Craiova aims to decrease the electrical consumption of its nine-year-old trams by 40 percent by using an innovative electronic chopper system. The city should also be able to increase transport capacity by putting the old trams into operation.

Implementing sustainable mobility

Craiova’s electric tram system and infrastructure belong to the 1980s. Therefore city needs to make improvements, increase passenger safety and comfort and make substantial reductions in costs. The electric transport fleet is represented by 36 tramways and 36km of tram tracks. Twenty seven of these trams are in operation and nine lines have not been used because they have an old driving system with high electrical consumption. This system can be replaced with an electronic driving system called a chopper and the nine trams could operate again.

This will lead to increased capacity with more than 4.5 million passengers per year travelling on the main axis of Craiova, contributing to decreasing the congestion on crowded urban roads and putting less pressure on car parks. The new driving system would be assisted by an onboard computer and a Windows application, which stores and processes the data from the entire driving system. With all 36 trams in operation 80 to 90 percent of municipal public transport will be covered.

Progress

As part of the planning phase, a technical solution for anti skidding of the driving wheels was developed by one of the partners, IPA. This was proposed as a patent at the State Office for Inventions and Trademarks.  The final document developed contains arguments for upgrading the electrical system of trams, general considerations concerning the structure and technical requirements of chopper system. The engineering team then developed a chopper prototype, which was tested and the final version of the equipment specifications was defined. Several tests were carried out and the equipment met all the requirements.

Tender documentation was developed based on research into the modernisation of electrical drive systems, according to current legislation, and following some solutions adopted by other transport operators. The tramway modernisation action includes two major changes at the traction part: the replacement of old drive system with choppers, which assure current control in all working regimes and the replacement of the classic auxiliary services source with a static source which feeds all the auxiliary consumers. All nine trams have had the chopper system installed and four are already running in the city.

The tram technicians were trained in April 2010 when the first trams were modernised. The training programme will continue for the duration of the implementation and has theoretical and practical segments to ensure the system is correctly maintained after the installation. Tram drivers were also trained as the upgraded trams have new onboard equipment, which provides more information and functions that drivers need to familarise themselves with.

Outcomes

The measure led to:

• A 40 percent reduction in the electric power consumption of the trams endowed with choppers;
• Lower exploitation costs;
• Increased transport capacity; and
• Increased passenger safety and comfort.