Daily life

What is a catenary line? Discover how we power our trains!

Without the catenary line, our trains and tramways wouldn’t go anywhere! A catenary line is a set of suspension cables that allows us to power our rolling stock, notably the RER. How does it works?

The catenary line is used to transmit electrical power to our trains and trams. The set of suspension cables is powered via rectification sub-stations, which transform the industrial current that arrives at the sub-station into the appropriate current for the RER (1,500 volts) or tramway (750 volts). The RER car or tramway is itself powered by pantographs, articulated devices that harness the current through friction.

The first catenary tests were validated in 1910 by PLM, the Compagnie des Chemins de fer de Paris à Lyon et à la Méditerranée, and by the Compagnie des Chemins de fer du Midi.

Catenary lines are now the norm for railways, which includes our RER network. The word has also entered into everyday language. However, in railroad parlance it is more common to say aerial contact line (ACL), the generic term to designate power systems – i.e. the contact wire (and not the cable), fixtures, etc.

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