The infrastructure of electric rolling stock necessarily includes contact networks. Thanks to this provision, the supply of target pantographs is realized, which, in turn, set the vehicles in motion. There are many varieties of such networks, but they are all a collection of cables, fixing and reinforcing elements that provide power from electrical substations. The contact network is also used to service fixed objects, including various crossings and lighting stations.
General information about contact networks
This is part of a technical facility that is part of a complex of electrified tracks and roads. The main task of this infrastructure is the transmission of energy from the traction substation to electric rolling stock. In order to ensure the possibility of supplying equipment with energy from several substations, the contact network is divided into several sections. Thus, sections are formed, each of which is fed by a separate feeder from a specific source.
Partitioning alsoused to facilitate repair operations. For example, in the event of a line failure, power transmission will be interrupted in only one section. Faulty wiring can be reconnected to an operating substation if needed, reducing downtime. In addition, the contact network of railways is provided with special insulators. This decision is due to the fact that the accidental formation of an arc at the time of passage of the current collectors can disrupt the main sheath of the wires.
Contact network device
Networks of this type are a whole complex of electrical infrastructure components. In particular, a typical device of this structure includes power cables, special suspensions, fittings and its special parts, as well as supporting structures. To date, an instruction is used, in accordance with which parts, fittings of the contact network and wires undergo a special procedure of thermal diffusion galvanization. Mild and carbon steel elements are protected by a protective treatment to increase the strength and durability of communications.
Features of overhead contact networks
Aerial networks are the most common due to space savings and more efficient organization of electrical lines. True, there are also disadvantages of such a device, which are expressed in higher costs for installation and maintenance. So, the overhead contact network includes a carrier cable, fittings, wires, arrows with intersections, as well as insulators.
The main design features of networks of this type come down to the method of placement. Communications are suspended on special supports. In this case, sagging wires may be noted between the installation points. It is impossible to completely eliminate this flaw, but its presence can harm power lines. For example, if the support of the contact network allows for strong sagging, then the current collector moving along the cable at the suspension points may lose connection with its line.
Railway contact networks
In this case, we are talking about the classic version of the contact network. It is the railways that use the largest volumes of materials for the electrification of rolling stock. The wire itself for such purposes is made of electrolytic hard-drawn copper with a cross-sectional area of up to 150 mm2. As for the support elements, the railway contact network is provided by reinforced concrete or metal installations, the height of which can reach 15 m. The gaps from the axis of the extreme tracks to the outer sides of the supports at stations and stages are no more than 310 cm. True, there are exceptions - for example, in In difficult conditions, the technology allows the gap to be reduced to 245 cm. Traditional methods of protecting wires of this type are used - division into separate sections, the use of insulators and neutral inserts.
Trolleybus contact network
Compared to rail transport, the movement of a trolleybus does not imply a permanent electrical connection with the surface. Alsothe requirements for maneuverability are increasing, which leads to changes in the organization of the electrification infrastructure. These differences determined the main feature of the electrical networks for trolleybuses - the presence of two-wire lines. At the same time, each wire is fixed at small intervals and is provided with reliable insulation. As a result, the contact network becomes more complicated both in straight sections and in the areas of branching and intersections. The features include the widespread use of sectioning with appropriate insulators. But in this case, the sheath not only protects the wires from contacts with each other, but also protects the material at the intersection. In addition, the use of arc pantographs and pantographs is not allowed in the infrastructure of trolleybus networks.
Tram contact networks
Tram contact networks usually use wires made of copper and similar alloys. Also, the possibility of using steel-aluminum wires is not excluded. The coupling of sections with different suspension heights is carried out with a wiring slope in relation to the longitudinal profile of the track. In this case, the deviation can vary from 20 to 40%, depending on the complexity and conditions of the line laying section. On straight sections, the contact network of the tram is located in a zigzag pattern. At the same time, the zigzag step - regardless of the type of suspension - does not exceed four spans. It is also necessary to note the deviation of the contact cables from the pantograph axis - this value, as a rule, is no more than 25 cm.
Conclusion
Despite the technological development of electrification systems, contact networks in the main design options retain the traditional device. Changes in terms of improving technical and operational parameters affect only some aspects of the use of parts. In particular, the contact network of railways is increasingly supplied with elements that have undergone thermal diffusion galvanization. Additional processing of the element base undoubtedly increases the reliability and durability of the lines, but contributes to a radical technical improvement to a minimal extent. The same applies to tram and trolleybus electric networks, in which, however, fixing devices, the strength of reinforcement and parts of suspended structures have been significantly improved lately.
