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A cool concept for an innovative transformer

The totally new natural air-cooled transformer now entering commercial service is a technological and economic success story. Here we see how the winds of innovation are blowing across the roof of a tram-train.



An industrial partnership with Mitsubishi Electric
The transformer installed on the fleet of 15 tram-trains running on the T4 and P lines of the Paris Transilien commuter network is the crucial component that converts the 25,000 volts of electricity flowing through the catenaries to the 2,000 volts utilisable by the trains.
The frequent oil leaks plaguing the Avanto series of transformers have hurt rolling stock availability and added to maintenance costs, so in 2016 SNCF launched a project in 2016 to deal with the unreliability of this equipment. In September 2017, the railway entered into a partnership with Japan’s Mitsubishi Electric to develop a new transformer. Like its predecessor, it would also be oil-cooled, but the cooling would be done by the natural passage of air through a multitude of pipes rather than by energy-greedy and noisy motor-driven fans. Built and tested in the summer of 2018 at the Mitsubishi Ako plant in Japan, this 2-tonne unit was then sent to the Noisy-le-Sec maintenance Technicentre, where it was installed on an SNCF TT02 train. In April 2019, this train ran without difficulty on the CEF 2 test loop at Bar-le-Duc. Testing in commercial service will begin in autumn 2019 and continue for one year.

The key figures of the JP4AVANTO’s success

1st in the world
The rooftop installation of a transformer with natural air cooling that has been done on the SNCF tram-train is a first anywhere in the world. Some rolling stock in Japan is already equipped with this type of transformer, but it is installed under the train body. This is also the first time that SNCF has purchased a power train subsystem from a supplier other than the rolling stock manufacturer.

This is the amount of energy saved by the natural air-cooled transformer, compared with the original conventional transformer, owing to its greater efficiency and elimination of auxiliary units (motor-driven fans). Lower energy consumption means smaller electric bills.

This is the number of entities in the SNCF group teamed up in this project:

  • The Tech4Rail programme of the SNCF Innovation and Research Department
  • The Safety and Operations Department – Transilien Rolling Stock
  • The Railway Testing Agency
  • The Rolling Stock Engineering Centre at Le Mans, the engineering units of the Rolling Stock Department at Nevers and Hellemmes, and the Technicentre at Noisy le Sec (tram-train workshop).

– 13 decibels
This is the reduction in sound emissions obtained with the new transformer, representing a benefit for both passengers and people along the tracks.

– 70%
The reduction in the number of maintenance operations that will be required by the new transformer, compared with the conventional one. A visual inspection is all that is needed, thus saving even more money.

This is the compatibility level of the new transformer with the Avanto model tram-train. To comply with specifications, no electrical, mechanical, or functional modifications were necessary to equip the rolling stock with a natural air-cooled transformer, thus reducing the cost of installation. Its replicability rate is another aspect of JP4AVANTO’s success. Other types of SNCF rolling stock, including those powered by low-consumption technologies like batteries, hydrogen, or hybrid power, could benefit from this type of transformer in the future.

For more information, watch the video.