Others, for example those designed to export power from a remote power station such as the Itaipu scheme in Brazil, may be optimised for power flow in only one preferred direction.

Electric traction systems (where electric power is generated at a remote power station and transmitted to the trains) are considerably more cost-effective than diesel or steam units, where separate power units must be carried on each train.

A Road Powered Electric Vehicle therefore necessarily includes a system for supplying electricity from an external power source (such as a remote power station through a network of power coupling elements which provide an integral and continuous power connection between origin and destination.