Catenary wires are kept in mechanical tension because the pantograph causes mechanical oscillations in the wire. The waves must travel faster than the train to avoid producing standing waves, which could break the wire. Tensioning the line makes waves travel faster, and also reduces sag from gravity.
Catenary wires are kept in mechanical tension because the pantograph causes mechanical oscillations in the wire. The waves must travel faster than the train to avoid producing standing waves which could break the wire. Tensioni,ng the line makes waves travel faster, and also reduces sag from gravity.