The electric supply for traction

Published on 25 February 2008

The electric motors used for traction are either powered from catenaries or rails.

In France, trains and most trams are powered from catenaries. They require a considerable amount of unsightly infrastructure but mean the contact wires are out of the reach of the public.

Rails are used in metros because of the small size of the tunnels. They are usually adjacent to the running rails and cannot be reached by the public.

New rail supply systems are being developed for trams, but they require a complex power system to ensure that only the rail under the tram is powered up.

Catenaries and power rails receive electricity from the national grid, via transformers located next to the tracks.

a TGV catenary (photo DR).
the parts of a catenary (illustration RR, see To find out more).