Contact Line Systems
Effective design for simple contact lines, catenary lines, or overhead contact rails to complicated station systems
Contact lines serve to supply electrical power from the substations to the train sets and locomotives. These are mostly overhead lines, for which there are numerous designs, for example: simple contact lines, catenary lines or overhead contact rails. For each of these basic types, there are usually railway company-specific or country-specific methods of construction, that vary in their geometry and the construction components used.
As a result of varying electrical requirements, there are also differences in construction for overhead contact lines for a.c. and d.c. railway systems. In the case of d.c. railway systems, electrified rails, also termed ‘third rails’, are normally used - sometimes as an alternative to an overhead contact line - for voltages up to a maximum of DC 1,5 kV. These are slightly elevated mounted on the side of the tracks. In isolated cases there are systems with an additional return circuit rail, when the running rails are not used for return current flow.
Apart from the electrical capacity, which is based on the nominal voltage, the rolling stock and the amount of traffic, the contact line system must meet mechanical requirements resulting from traffic speeds, the dynamic contact forces of the current collector and the construction conditions.
Effective design for systems of this kind is nowadays possible only with the relevant tools. For this KEMA has developed its own CAD-based overhead contact line design software OLACAD, which facilitates engineering for all types of overhead contact line. This software can be used for local or long-distance traffic, across all speed zones, by means of its module and database structure. The relevant construction methods and guidelines specific to the railway system and/or the manufacturer are complied with in full and form the basis for the design.
The OLACAD design tool allows - dependent on as-built, track and situational drawings - the actual overhead contact lines to be planned. This overhead contact line consists of contact wire - in the case of catenaries the messenger were - the flexible head span structures and cantilevers, the masts, the tensioning devices and anchoring points, the insulators and the section insulators, booster and return wires, the foundations and the switching devices. Apart from the systems on open lines and in tunnels, complicated station systems, depots and workshops, and, in the case of trams, complex crossings can easily be planned. Special modules allow the planning of portals and overhead contact rails. There is an optional function that allows various construction phases to be planned for - ranging from initial conditions through to the final stage of construction.