Contact network of railways distance. Contact network device

A complex of devices for the transmission of electricity from traction substations to EPS through current collectors. Contact network it is part of the traction network and for rail electrified transport it usually serves as its phase (with alternating current) or pole (with direct current); the other phase (or pole) is the rail network.
The contact network can be made with a contact rail or contact suspension. Running rails were first used to transmit electricity to a moving vehicle in 1876 by the Russian engineer F. A. Pirotsky. The first contact suspension appeared in 1881 in Germany.
The main elements of a contact network with a contact suspension (often called air) are the wires of the contact network (contact wire, carrier cable, reinforcing wire, etc.), supports, supporting devices (cantilevers, flexible crossbars and rigid crossbars) and insulators. Contact networks with contact suspensions are classified: according to the type of electrified transport for which the contact network is intended, - main, including high-speed, railway, tram and quarry transport, mine underground transport, etc .; by the nature of the current and the rated voltage of the EPS powered by the contact network; on the placement of the contact suspension relative to the axis of the rail track - for the central (main railway transport) or lateral (industrial transport) current collection; by type of contact suspension - contact networks with a simple, chain or special suspension; according to the features of implementation - contact networks of hauls, stations, for arts, structures.
Unlike other power supply devices, the contact network does not have a reserve. Therefore, increased requirements are imposed on the reliability of the contact network, taking into account which design, construction and installation, maintenance of the contact network and repair of the contact network are carried out.
The choice of the total cross-sectional area of ​​\u200b\u200bthe wires of the contact network is usually carried out when designing a traction power supply system. All other issues are solved with the help of the contact network theory, an independent scientific discipline, the formation of which was largely facilitated by the work of owls. scientist I. I. Vlasov. Based on the design issues of the contact network are: the choice of the number and brands of its wires in accordance with the results of calculations of the traction power supply system, as well as traction calculations, the choice of the type of contact suspension in accordance with the max, speeds of the ERS and other current collection conditions; determination of the span length (mainly according to the condition of ensuring its wind resistance); selection of types of supports and supporting devices for hauls and stations; development of contact network designs in arts, structures; placement of supports and drawing up plans for the contact network of stations and spans with the coordination of zigzags of wires and taking into account the implementation of air arrows and sectioning elements of the contact network (insulating interfaces of anchor sections, sectional insulators and disconnectors). When choosing methods of construction and installation of a contact network in the course of electrification of railways, they strive to have them as little as possible reflected in the transportation process, while unconditionally ensuring the high quality of work.
The main industries, enterprises for the construction of a contact network are construction and installation trains and electrical installation trains. The organization and methods of maintenance and repair of the contact network are selected from the conditions for providing a given high level reliability of the contact network at the lowest labor and material costs, labor safety of workers in the areas of the contact network, possibly less impact on the organization of train traffic. Production, acceptance for the operation of the contact network is the distance of the power supply.
The main dimensions (see fig.), characterizing the placement of the contact network relative to other posts, devices. e., - height H of suspension of the contact wire above the level of the top of the rail head;


The main elements of the contact network and the dimensions characterizing its placement relative to other permanent devices of the main railways: Pks - wires of the contact network; O - support of the contact network; And insulators.
distance A from live parts to grounded parts of structures and rolling stock; distance G from the axis of the extreme path to the inner edge of the contact network supports at the level of the rail heads.
Improving the design of the contact network is aimed at increasing its reliability while reducing the cost of construction and operation. J.-b. contact network supports and foundations of metal supports are made taking into account the electrocorrosive effect of stray currents on their fittings. An increase in the service life of the contact wire is achieved, as a rule, by using carbon contact inserts on current collectors.
During the maintenance of the contact network on domestic railways. e. without stress relief, insulating removable towers, mounting railcars are used. The list of works performed under voltage was expanded due to the use of double insulation on flexible crossbars, in wire anchors and other elements of the contact network. Many control operations are carried out by means of their diagnostics, which are equipped with laboratory cars. The efficiency of switching sectional disconnectors of the contact network has increased significantly due to the use of telecontrol. The equipping of power supply distances with specialized mechanisms and machines for repairing the contact network (for example, for digging pits and installing supports) is increasing.
An increase in the reliability of contact networks is facilitated by the use of ice melting methods developed in our country, including without interrupting train traffic, electrorepellent protection, wind-resistant diamond-shaped contact suspension, etc. To determine the number of areas of contact networks and the boundaries of service areas, they use the concepts of operational length and deployed the length of electrified tracks, equal to the sum of the lengths of all anchor sections of contact networks within the specified limits. On domestic railways, the developed length of electrified tracks is an accounting indicator for districts of electricity supply, distances of electricity supply, and road sections, and exceeds the operational length by more than 2.5 times. The determination of the need for materials for the repair and maintenance needs of contact networks is carried out according to its expanded length.

A contact network is a special power line that serves to supply electrical energy to an electric rolling stock. Its specific feature is that it should provide current collection to moving electric locomotives. The second specific feature of the contact network is that it cannot have a reserve. This leads to increased requirements for the reliability of its operation.
The contact network consists of a contact suspension of the track, supports of the contact network, supporting and fixing devices in the space of the wires of the contact network. In turn, the contact suspension is formed by a system of wires - a carrier cable and contact wires. For traction system direct current there are usually two contact wires in the suspension and one for the AC traction system. On fig. 6 shows a general view of the contact network.

The traction substation supplies electricity to the rolling stock through a contact network. Depending on the connection of the contact network with traction substations and between contact suspensions of other tracks of a multi-track section, the following schemes are distinguished within the boundaries of a separate inter-substation zone: a) separate two-way;

Rice. 1. General view of the contact network

b) nodal; c) parallel.


a)

in)
Rice. Fig. 2. Main power supply schemes for catenary rails a) – separate; b) - nodal; c) is parallel. PPS - points of parallel connection of contact suspensions of various ways; PS - sectioning post; TP - traction substation

Separate two-way circuit - a power circuit for contact suspensions, in which energy is supplied to the contact network from two sides, (adjacent traction substations operate in parallel to the traction network), however, contact suspensions are not electrically connected to each other within the boundaries of the inter-substation zone. The scope of such a scheme is the supply of electric railway sections with non-extended inter-substation zones and relatively uniform power consumption in directions.
Nodal scheme - a scheme that differs from the previous one by the presence of an electrical connection between the track suspensions. Such communication is carried out using the so-called sectioning posts of the contact network. The technical equipment of the sectioning posts of the contact network allows, if necessary, to eliminate not only the transverse connection between the track suspensions, but also the longitudinal one, breaking the contact network within the boundaries of the inter-substation zone into separate electrically unconnected sections. This significantly increases the reliability of the traction power supply system. On the other hand, the presence of a node in normal modes allows more efficient use of contact networks for the transmission of electrical energy to the electric rolling stock, which provides significant energy savings in case of uneven power consumption in directions. Consequently, the scope of such a suspension is sections of an electric railway with extended inter-substation zones and significant uneven power consumption in directions.
Parallel circuit - a circuit that differs from the nodal circuit by a large number of electrical nodes between the catenary rails. It is used for even greater uneven consumption of electricity along the tracks. This scheme is especially effective when driving heavy trains.

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 all of them are a combination of cables, fixing and reinforcing elements that provide power from. Also, 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 structure, which is part of a complex of electrified tracks and roads. The main task of this infrastructure is to transfer energy from 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.

Sectioning is also used 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 connected to an operating substation if necessary, 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.

The device of contact networks

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. Elements are made of low-carbon and are subjected to protective treatment to increase the strength and durability of communications.

Features of overhead contact networks

Overhead networks are 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 are reduced 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 be harmful. 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 contact 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 mm 2. 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. The requirements for maneuverability are also 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.

Contact networks of trams

In tram contact networks, wires made of copper and alloys of similar characteristics are usually used. 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 axis of the pantograph - 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 is increasingly supplied with elements that have undergone thermal diffusion galvanization. Additional processing 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 electrical networks, in which, however, recently the fixing devices, the strength of the reinforcement and parts of suspended structures have been significantly improved.

Contact network is a set of devices for transmitting electricity from traction substations to EPS through pantographs. It is part of the traction network and for rail electrified transport it usually serves as its phase (with alternating current) or pole (with direct current); the other phase (or pole) is the rail network. The contact network can be made with a contact rail or with a contact suspension.
In a contact network with a contact suspension, the main elements are the following: wires - a contact wire, a supporting cable, a reinforcing wire, etc .; supports; supporting and fixing devices; flexible and rigid cross members (consoles, clamps); insulators and fittings for various purposes.
A contact network with a contact suspension is classified according to the type of electrified transport for which it is intended - railway. mainline, city (tram, trolley bus), quarry, mine underground rail transport, etc.; by the nature of the current and the rated voltage of the EPS powered by the network; on the placement of the contact suspension relative to the axis of the rail track - for the central current collection (on the main railway transport) or side (on the ways of industrial transport); by type of contact suspension - with a simple, chain or special; according to the features of the anchoring of the contact wire and the carrier cable, the interfaces of the anchor sections, etc.
The contact network is designed to operate outdoors and therefore is exposed to climatic factors, which include: ambient temperature, humidity and air pressure, wind, rain, frost and ice, solar radiation, the content of various contaminants in the air. To this it is necessary to add thermal processes that occur when the traction current flows through the elements of the network, the mechanical effect on them from the current collectors, electrocorrosion processes, numerous cyclic mechanical loads, wear, etc. All devices of the contact network must be able to withstand the action of the listed factors and provide high current collection quality in any operating conditions.
Unlike other power supply devices, the contact network does not have a reserve, therefore, increased requirements are imposed on it in terms of reliability, taking into account which its design, construction and installation, maintenance and repair are carried out.

Contact network design

When designing a contact network (CS), the number and brand of wires are selected based on the results of calculations of the traction power supply system, as well as traction calculations; determine the type of contact suspension in accordance with the maximum speeds of the ERS and other current collection conditions; find the span lengths (ch. arr. according to the conditions for ensuring its wind resistance, and at high speeds - and a given level of elasticity unevenness); choose the length of anchor sections, types of supports and supporting devices for hauls and stations; develop CS designs in artificial structures; place supports and draw up plans for the contact network at stations and stages with the coordination of zigzags of wires and taking into account the implementation of air arrows and sectioning elements of the contact network (insulating interfaces of anchor sections and neutral inserts, sectional insulators and disconnectors).
The main dimensions (geometric indicators) characterizing the placement of the contact network relative to other devices are the height H of hanging the contact wire above the level of the top of the rail head; distance A from live parts to grounded parts of structures and rolling stock; the distance G from the axis of the extreme path to the inner edge of the supports, located at the level of the rail heads, are regulated and largely determine the design of the elements of the contact network (Fig. 8.9).

Improving the design of the contact network is aimed at increasing its reliability while reducing the cost of construction and operation. Reinforced concrete supports and foundations of metal supports are made with protection against electrocorrosive effects on their reinforcement of stray currents. An increase in the service life of contact wires is achieved, as a rule, by using inserts with high antifriction properties (carbon, including metal-containing; metal-ceramic, etc.) on current collectors, by choosing a rational design of current collectors, and by optimizing current collection modes.
To improve the reliability of the contact network, ice is melted, incl. without interruption of train traffic; wind-resistant contact suspensions are used, etc. The efficiency of work on the contact network is facilitated by the use of remote control for remote switching of sectional disconnectors.

Wire anchoring

Anchoring wires - attaching the wires of the contact suspension through the insulators and fittings included in them to the anchor support with the transfer of their tension to it. Anchoring of wires can be uncompensated (rigid) or compensated (Fig. 8.16) through a compensator that changes the length of the wire if its temperature changes while maintaining the specified tension.

In the middle of the anchor section of the contact suspension, an average anchoring is performed (Fig. 8.17), which prevents unwanted longitudinal movements towards one of the anchorages and allows you to limit the damage zone of the contact suspension when one of its wires breaks. The cable of the middle anchorage is attached to the contact wire and the carrier cable with appropriate fittings.

Wire strain compensation

Compensation of wire tension (automatic control) of the contact network when their length changes as a result of temperature effects is carried out by compensators of various designs - block-load, with drums of various diameters, hydraulic, gas-hydraulic, spring, etc.
The simplest is a block-cargo compensator, consisting of a load and several blocks (chain hoist), through which the load is attached to the anchored wire. The most widespread is the three-block compensator (Fig. 8.18), in which the fixed block is fixed on a support, and two movable ones are embedded in loops formed by a cable carrying the load and fixed at the other end in the stream of the fixed block. The anchored wire is attached to the movable block through insulators. In this case, the weight of the load is 1/4 of the nominal tension (a gear ratio of 1:4 is provided), but the movement of the load is twice that of a two-to-6-arm compensator (with one moving block).

compensators with drums of different diameters (Fig. 8.19), cables connected with anchored wires are wound on a drum of small diameter, and a cable connected to a garland of loads is wound on a drum of a larger diameter. The braking device is used to prevent damage to the contact suspension in the event of a wire break.

Under special operating conditions, especially with limited dimensions in artificial structures, minor temperature differences in heating wires, etc., compensators of other types are also used for catenary wires, fixing cables and rigid crossbars.

Contact wire holder

The articulated latch consists of three elements: the main rod, the stand and the additional rod, at the end of which the fixing clip of the contact wire is attached (Fig. 8.20). The weight of the main rod is not transferred to the contact wire, and it takes only part of the weight of the additional rod with a fixing clip. The rods are shaped to ensure reliable passage of the current collectors when they squeeze out the contact wire. For high-speed and high-speed lines, lightweight additional rods are used, for example, made of aluminum alloys. With a double contact wire, two additional rods are installed on the rack. On the outer side of curves of small radii, flexible clamps are mounted in the form of a conventional additional rod, which is attached through a cable and an insulator to a bracket, rack, or directly to a support. On flexible and rigid crossbars with fixing cables, strip retainers (similar to an additional rod) are usually used, hinged with clamps with an eye mounted on the fixing cable. On rigid crossbars, it is also possible to mount clamps on special racks.

Anchor section

Anchor section - a contact suspension section, the boundaries of which are anchor supports. The division of the contact network into anchor sections is necessary to include devices in the wires that maintain the tension of the wires when their temperature changes and to carry out longitudinal sectioning of the contact network. This division reduces the damage zone in the event of a break in the wires of the contact suspension, facilitates installation, tech. maintenance and repair of the contact network. The length of the anchor section is limited by permissible deviations from the nominal value of the tension of the catenary wires set by the compensators.
Deviations are caused by changes in the position of the strings, detents and consoles. For example, at speeds up to 160 km/h, the maximum length of the anchor section with two-sided compensation on straight sections does not exceed 1600 m, and at speeds of 200 km/h, no more than 1400 m is allowed. In curves, the length of the anchor sections decreases the more, the greater the length curve and its radius is smaller. To move from one anchor section to the next, non-insulating and insulating mates are performed.

Conjugation of anchor sections

Pairing of anchor sections is a functional combination of two adjacent anchor sections of the contact suspension, which ensures a satisfactory transition of the ERS pantographs from one of them to the other without violating the current collection mode due to the appropriate placement in the same (transitional) spans of the contact network of the end of one anchor section and the beginning of another. There are non-insulating mates (without electrical sectioning of the contact network) and insulating (with sectioning).
Non-insulating mates are performed in all cases when it is required to include compensators in the wires of the catenary. This achieves mechanical independence of the anchor sections. Such mates are mounted in three (Fig. 8.21, a) and less often in two spans. On high-speed lines, interfacing is sometimes performed in 4-5 spans due to higher requirements for the quality of the current collection. On non-insulating mates there are longitudinal electrical connectors, the cross-sectional area of ​​which must be equivalent to the cross-sectional area of ​​the wires of the contact network.

Insulating interfaces are used when it is necessary to section off the contact network, when, in addition to mechanical, it is necessary to ensure the electrical independence of the mating sections. Such pairings are arranged with neutral inserts (sections of the contact suspension, on which there is normally no voltage) and without them. In the latter case, three- or four-span mates are usually used, placing the contact wires of the mating sections in the middle span (spans) at a distance of 550 mm from one another (Fig. 8.21.6). In this case, an air gap is formed, which, together with the insulators included in the raised contact suspensions at the transitional supports, ensures the electrical independence of the anchor sections. The transition of the pantograph skid from the contact wire of one anchor section to another occurs in the same way as with non-insulating pairing. However, when the pantograph is in the middle span, the electrical independence of the anchor sections is violated. If such a violation is unacceptable, neutral inserts of different lengths are used. It is chosen such that, with several pantographs of one train raised, simultaneous overlapping of both air gaps is excluded, which would lead to a short circuit of wires powered by different phases and under different voltages. In order to avoid burnout of the contact wire of the EPS, the interface with the neutral insert takes place on the freewheel, for which, 50 m before the start of the insert, the signal sign “Turn off the current” is installed, and after the end of the insert, with electric locomotive traction after 50 m and with multiple unit traction after 200 m, the sign “ Turn on the current "(Fig. 8.21, c). In areas with high-speed traffic, automatic means switching off the current on the EPS. In order to be able to withdraw the train when it is forced to stop under the neutral insert, sectional disconnectors are provided for temporarily supplying voltage to the neutral insert from the direction of train movement.

Sectioning of the contact network

On fig. 8.22 shows an example of a power supply and sectioning scheme for a station located on a double-track section of a line electrified on alternating current. The diagram shows seven sections - four on hauls and three at the station (one of them with mandatory grounding when it is turned off). The contact network of the left haul tracks and the station is powered by one phase of the power system, and the right haul tracks are powered by the other. Accordingly, sectioning was performed using insulating mates and neutral inserts. In areas where ice melting is required, two sectional disconnectors with motor drives are installed on the neutral insert. If ice melting is not provided, one sectional disconnector with a manual drive is sufficient.

For sectioning the contact network of the main and side networks at the stations, sectional insulators are used. In some cases, sectional insulators are used to form neutral inserts on the AC contact network, which the EPS passes without consuming current, as well as on tracks where the length of the ramps is insufficient to accommodate insulating mates.
Connection and disconnection of various sections of the contact network, as well as connection with supply lines, is carried out using sectional disconnectors. On AC lines, as a rule, disconnectors of a horizontal rotary type are used, on DC lines - vertically chopping. The disconnector is controlled remotely from the consoles installed in the duty station of the contact network area, in the premises of those on duty at the stations and in other places. The most critical and frequently switched disconnectors are installed in the dispatch telecontrol network.
There are longitudinal disconnectors (for connecting and disconnecting the longitudinal sections of the contact network), transverse (for connecting and disconnecting its transverse sections), feeder, etc. They are designated by the letters of the Russian alphabet (for example, longitudinal -A, B, C, G; transverse - P ; feeder - F) and numbers corresponding to the numbers of tracks and sections of the contact network (for example, P23).
To ensure the safety of work on the disconnected section of the contact network or near it (in the depot, on the ways of equipping and inspecting the roof equipment of the EPS, on the ways of loading and unloading cars, etc.), disconnectors with one grounding knife are installed.

Frog

Air switch - formed by the intersection of two contact suspensions above the turnout; designed to ensure a smooth and reliable passage of the pantograph from the contact wire of one path to the contact wire of another. The crossing of wires is carried out by superimposing one wire (usually an adjacent path) on another (Fig. 8.23). To lift both wires when the current collector approaches the air arrow, a restrictive metal pipe 1-1.5 m long is fixed on the lower wire. The upper wire is placed between the tube and the lower wire. The crossing of the contact wires over a single turnout is carried out with the displacement of each wire to the center from the axes of the tracks by 360-400 mm and is located where the distance between the inner faces of the heads of the connecting rails of the cross is 730-800 mm. At cross turnouts and at the so-called. At blind intersections, the wires cross over the center of the turnout or intersection. Air gunners perform, as a rule, fixed. To do this, clamps are installed on the supports that hold the contact wires in a predetermined position. On station tracks (except for the main ones), the switches can be made non-fixed if the wires above the turnout are located in the position specified by adjusting the zigzags at the intermediate supports. Contact suspension strings located near the arrows must be double. Electrical contact between contact suspensions forming an air arrow is provided by an electrical connector installed at a distance of 2-2.5 m from the point of intersection on the side of the wit. To increase reliability, switch designs are used with additional cross-links between the wires of both contact suspensions and sliding supporting double strings.

Contact network supports

Contact network supports - structures for fixing the supporting and fixing devices of the contact network, perceiving the load from its wires and other elements. Depending on the type of supporting device, the supports are divided into cantilever (single-track and double-track execution); racks of rigid crossbars (single or paired); supports of flexible crossbars; feeder (with brackets only for supply and exhaust wires). Supports on which there are no supporting, but there are fixing devices, are called fixing. Cantilever supports are divided into intermediate ones - for attaching one contact suspension; transitional, installed at the junctions of the anchor sections, - for fastening two contact wires; anchor, perceiving the force from the anchoring of wires. As a rule, supports perform several functions at the same time. For example, the support of the flexible crossbar can be anchored, consoles can be suspended on the uprights of the rigid crossbar. Brackets for reinforcing and other wires can be fixed to the support posts.
Supports are made of reinforced concrete, metal (steel) and wood. On domestic railways d. mainly used supports made of prestressed reinforced concrete (Fig. 8.24), conical centrifuged, standard length 10.8; 13.6; 16.6 m. Metal supports are installed in cases where it is impossible to use reinforced concrete ones due to their bearing capacity or dimensions (for example, in flexible crossbars), as well as on lines with high-speed traffic, where there are increased requirements for the reliability of support structures. Wooden supports are used only as temporary.

For DC sections, reinforced concrete poles are made with additional bar reinforcement located in the foundation part of the poles and designed to reduce damage to the pole reinforcement by electrocorrosion caused by stray currents. Depending on the method of installation, reinforced concrete supports and racks of rigid crossbars are separate and inseparable, installed directly into the ground. The required stability of inseparable supports in the ground is provided by the upper bed or base plate. In most cases, inseparable supports are used; separate ones are used with insufficient stability of inseparable ones, as well as in the presence of groundwater, which makes it difficult to install inseparable supports. In anchor reinforced concrete supports, braces are used, which are installed along the path at an angle of 45 ° and attached to reinforced concrete anchors. Reinforced concrete foundations in the above-ground part have a cup 1.2 m deep, in which supports are installed and then the sinuses of the cup are sealed with cement mortar. To deepen foundations and supports into the ground, the vibration immersion method is mainly used.
Metal supports of flexible crossbars are usually made of a tetrahedral pyramidal shape, their standard length is 15 and 20 m. In areas characterized by increased atmospheric corrosion, metal cantilever supports 9.6 and 11 m long are fixed in the ground on reinforced concrete foundations. Cantilever supports are installed on prismatic three-beam foundations, flexible crossbeam supports are installed either on separate reinforced concrete blocks or on pile foundations with grillages. The base of the metal supports is connected to the foundations with anchor bolts. To fix supports in rocky soils, heaving soils of permafrost and deep seasonal freezing regions, in weak and swampy soils, etc., foundations of special structures are used.

Console

The console is a supporting device fixed on a support, consisting of a bracket and a rod. Depending on the number of overlapped paths, the console can be one-, two-, and rarely multi-track. To eliminate the mechanical connection between contact suspensions of different tracks and to increase reliability, single-track consoles are more often used. Uninsulated or grounded consoles are used, in which the insulators are located between the carrier cable and the bracket, as well as in the latch rod, and insulated consoles with insulators placed in the brackets and rods. Uninsulated consoles (Fig. 8.25) can be curved, inclined and horizontal in shape. For supports installed with an increased dimension, consoles with struts are used. At the junctions of the anchor sections, when mounting two consoles on one support, a special traverse is used. Horizontal consoles are used in cases where the height of the supports is sufficient to secure the inclined rod.

With isolated consoles (Fig. 8.26), it is possible to carry out work on the supporting cable near them without turning off the voltage. The absence of insulators on uninsulated consoles ensures greater stability of the position of the carrier cable under various mechanical influences, which favorably affects the current collection process. The brackets and rods of the consoles are fixed on supports with the help of heels, which allow them to be rotated along the axis of the track by 90 ° in both directions relative to the normal position.

Flexible cross member

Flexible crossbar - a supporting device for hanging and fixing the wires of the contact network located above several tracks. A flexible cross member is a system of cables stretched between supports across electrified tracks (Fig. 8.27). The transverse carrying cables take all vertical loads from the wires of the chain hangers, the cross member itself and other wires. The sag of these cables must be at least Vio the span between the supports: this reduces the effect of temperature on the height of the catenary hangers. To increase the reliability of the crossbars, at least two transverse load-bearing cables are used.

The fixing cables perceive horizontal loads (the upper one - from the carrying cables of chain suspensions and other wires, the lower one - from contact wires). The electrical isolation of the cables from the supports makes it possible to maintain the contact network without turning off the voltage. All cables to regulate their length are fixed on supports with threaded steel rods; in some countries, special dampers are used for this purpose, mainly for fixing contact suspension at stations.

current collection

Current collection - the process of transferring electrical energy from a contact wire or contact rail to the electrical equipment of a moving or stationary ERS through a current collector that provides sliding (on the main, industrial and most urban electric transport) or rolling (on some types of ERS of urban electric transport) electrical contact. Breaking the contact during current collection leads to the occurrence of non-contact arc erosion, resulting in intense wear of the contact wire and the contact inserts of the current collector. When the contact points are overloaded with current in the driving mode, contact electroexplosive erosion (sparking) and increased wear of the contacting elements occur. Long-term overload of the contact with the operating current or short-circuit current when the EPS is stopped can lead to burnout of the contact wire. In all these cases, it is necessary to limit the lower limit of contact pressure for given operating conditions. Excessive contact pressure, incl. as a result of aerodynamic impact on the pantograph, an increase in the dynamic component and the resulting increase in the vertical squeezing of the wire, especially at clamps, on overhead arrows, at the junction of anchor sections and in the area of ​​artificial structures, can reduce the reliability of the contact network and pantographs, as well as increase the wear rate wires and contact inserts. Therefore, the upper limit of contact pressure also needs to be normalized. Optimization of current collection modes is provided by coordinated requirements for contact network devices and current collectors, which guarantees high reliability of their operation at minimum reduced costs.
The quality of the current collection can be determined by different indicators (the number and duration of mechanical contact disturbances in the calculated section of the path, the degree of stability of the contact pressure close to the optimal value, the wear rate contact elements etc.), which largely depend on the design of the interacting systems - the contact network and current collectors, their static, dynamic, aerodynamic, damping and other characteristics. Despite the fact that the current collection process depends on a large number of random factors, the results of research and operating experience allow us to identify the fundamental principles for creating current collection systems with the required properties.

Rigid cross member

Rigid crossbar - serves to suspend the wires of the contact network located above several (2-8) tracks. A rigid cross member is made in the form of a block metal structure (crossbar) mounted on two supports (Fig. 8.28). Such cross members are also used for opening spans. The crossbar with the uprights is hingedly or rigidly connected with the help of struts, which allow unloading it in the middle of the span and reducing steel consumption. When placing lighting fixtures on the crossbar, a flooring with railings is performed on it; provide a ladder for climbing to the supports of service personnel. Install rigid cross bars. arr. at stations and points.

insulators

Insulators - devices for isolating wires of a contact network that are energized. There are insulators according to the direction of application of loads and the place of installation - suspended, tension, fixative and cantilever; by design - dish-shaped and rod; by material - glass, porcelain and polymer; insulators also include insulating elements
Suspension insulators - porcelain and glass dish-shaped - are usually connected in garlands of 2 on DC lines and 3-5 (depending on air pollution) on AC lines. Tension insulators are installed in wire anchorages, in load-bearing cables above sectional insulators, in fixing cables of flexible and rigid crossbars. Retaining insulators (fig. 8.29 and 8.30) differ from all others by the presence of an internal thread in the hole of the metal cap for fixing the pipe. On alternating current lines, rod insulators are usually used, and on direct current lines, disc insulators are also used. In the latter case, another disc insulator with an earring is included in the main rod of the articulated retainer. Cantilever porcelain rod insulators (Fig. 8.31) are installed in struts and rods of insulated consoles. These insulators must have increased mechanical strength, since they work in bending. In sectional disconnectors and horn arresters, porcelain rod insulators are usually used, less often disc insulators. In sectional insulators on DC lines, polymer insulating elements are used in the form of rectangular bars made of press material, and on AC lines, in the form of cylindrical fiberglass rods, which are covered with electrical protective covers made of fluoroplastic pipes. Polymeric rod insulators with fiberglass cores and silicone elastomer ribs have been developed. They are used as hanging, sectioning and fixing; they are promising for installation in struts and rods of insulated consoles, in cables of flexible cross members, etc. In areas of industrial air pollution and in some artificial structures, periodic cleaning (washing) of porcelain insulators is carried out using special mobile equipment.

Contact suspension

Contact suspension - one of the main parts of the contact network, is a system of wires, the relative position of which, the method of mechanical connection, material and cross section provide the necessary quality of current collection. The design of the contact suspension (KP) is determined by economic feasibility, operating conditions ( maximum speed EPS movement, the highest current taken by pantographs), climatic conditions. The need to ensure reliable current collection at increasing speeds and power of the EPS determined the trends in changing the designs of suspensions: first simple, then single with simple strings and more complex - single spring, double and special, in which to ensure the desired effect, ch. arr. alignment of the vertical elasticity (or stiffness) of the suspension in the span, space-cable systems with an additional cable or others are used.
At speeds up to 50 km / h, a satisfactory quality of current collection is ensured by a simple contact suspension, consisting only of a contact wire suspended from supports A and B of the contact network (Fig. 8.10, a) or transverse cables.

The quality of the current collection is largely determined by the sag of the wire, which depends on the resulting load on the wire, which is the sum of the dead weight of the wire (with ice along with ice) and wind load, as well as the length of the span and tension of the wire. The quality of the current collection is greatly influenced by the angle a (the smaller it is, the worse the quality of the current collection), the contact pressure changes significantly, shock loads appear in the support zone, there is increased wear of the contact wire and the current collector inserts of the current collector. It is possible to somewhat improve the current collection in the support zone by applying the suspension of the wire at two points (Fig. 8.10.6), which, under certain conditions, provides reliable current collection at speeds up to 80 km / h. It is possible to noticeably improve the current collection with a simple suspension only by significantly reducing the length of the spans in order to reduce the sag, which in most cases is uneconomical, or by using special wires with significant tension. In this regard, chain suspensions are used (Fig. 8.11), in which the contact wire is suspended from the carrier cable using strings. A suspension consisting of a carrier cable and a contact wire is called single; in the presence of an auxiliary wire between the carrier cable and the contact wire - double. In a chain suspension, the carrier cable and the auxiliary wire are involved in the transmission of traction current, so they are connected to the contact wire with electrical connectors or conductive strings.

The main mechanical characteristic of a contact suspension is considered to be elasticity - the ratio of the height of the contact wire to the force applied to it and directed vertically upwards. The quality of the current collection depends on the nature of the change in elasticity in the span: the more stable it is, the better the current collection. In simple and conventional chain hangers, the mid-span elasticity is higher than that of supports. Elasticity equalization in the span of a single suspension is achieved by installing spring cables 12-20 m long, on which vertical strings are attached, as well as by the rational arrangement of ordinary strings in the middle part of the span. Double pendants have more permanent elasticity, but they are more expensive and more difficult. To obtain a high index of uniformity of elasticity distribution in the span, various ways its increase in the zone of the support node (installation of spring shock absorbers and elastic rods, torsion effect from cable twisting, etc.). In any case, when developing suspensions, it is necessary to take into account their dissipative characteristics, i.e., resistance to external mechanical loads.
The contact suspension is an oscillatory system, therefore, when interacting with current collectors, it can be in a state of resonance caused by the coincidence or frequency multiplicity of its natural oscillations and forced oscillations, determined by the speed of the current collector along the span with a given length. In the event of resonance phenomena, a noticeable deterioration in current collection is possible. Limiting for the current collection is the speed of propagation of mechanical waves along the suspension. If this speed is exceeded, the current collector has to interact, as it were, with a rigid, non-deformable system. Depending on the normalized specific tension of the suspension wires, this speed can be 320-340 km/h.
Simple and chain hangers consist of separate anchor sections. Suspension fastenings “at the ends of the anchor sections can be rigid or compensated. On the main etc. mainly compensated and semi-compensated suspensions are used. In semi-compensated suspensions, compensators are available only in the contact wire, in compensated ones - also in the carrier cable. In this case, in the event of a change in the temperature of the wires (due to the passage of currents through them, changes in the ambient temperature), the sag of the carrier cable, and, consequently, the vertical position of the contact wires, remain unchanged. Depending on the nature of the change in the elasticity of the suspensions in the span, the sag of the contact wire is taken in the range from 0 to 70 mm. Vertical adjustment of semi-compensated suspensions is carried out so that the optimal sag of the contact wire corresponds to the average annual (for a given area) ambient temperature.
The structural height of the suspension - the distance between the carrier cable and the contact wire at the suspension points - is chosen based on technical and economic considerations, namely, taking into account the height of the supports, compliance with the current vertical dimensions of the approach of buildings, insulation distances, especially in the area of ​​artificial structures, etc .; in addition, a minimum inclination of the strings must be ensured at extreme ambient temperatures, when noticeable longitudinal movements of the contact wire relative to the carrier cable can occur. For compensated suspensions, this is possible if the carrier cable and the contact wire are made of different materials.
To increase the service life of the contact inserts of current collectors, the contact wire is placed in a zigzag plan. Possible various options suspension of the carrier cable: in the same vertical planes as the contact wire (vertical suspension), along the axis of the track (half-oblique suspension), with zigzags opposite to the zigzags of the contact wire (oblique suspension). Vertical suspension has less wind resistance, oblique - the greatest, but it is the most difficult to install and maintain. On straight sections of the track, semi-oblique suspension is mainly used, on curved sections - vertical. In areas with particularly strong wind loads, a diamond-shaped suspension is widely used, in which two contact wires suspended from a common carrier cable are located at supports with opposite zigzags. In the middle parts of the spans, the wires are drawn to each other by rigid strips. In some suspensions, lateral stability is ensured by the use of two carrying cables, which form a kind of cable-stayed system in the horizontal plane.
Abroad, single chain suspensions are mainly used, including in high-speed sections - with spring wires, simple spaced support strings, as well as with carrier cables and contact wires with increased tension.

contact wire

The contact wire is the most important element of the catenary suspension, directly making contact with the EPS current collectors in the process of current collection. As a rule, one or two contact wires are used. Two wires are usually used when removing currents of more than 1000 A. On domestic railways. e. use contact wires with a cross-sectional area of ​​​​75, 100, 120, less often 150 mm2; abroad - from 65 to 194 mm2. The cross-sectional shape of the wire has undergone some changes; in the beginning. 20th century the section profile acquired a shape with two longitudinal grooves in the upper part - the head, which serve to fix the contact network fittings on the wire. In domestic practice, the dimensions of the head (Fig. 8.12) are the same for different cross-sectional areas; in other countries the dimensions of the head depend on the cross-sectional area. In Russia, the contact wire is marked with letters and numbers indicating the material, profile and cross-sectional area in mm2 (for example, MF-150 is copper shaped, the cross-sectional area is 150 mm2).

In recent years, low-alloy copper wires with additives of silver and tin, which increase the wear and heat resistance of the wire, have become widespread. The best indicators in terms of wear resistance (2-2.5 times higher than that of copper wire) are bronze copper-cadmium wires, but they are more expensive than copper wires, and their electrical resistance is higher. The expediency of using one or another wire is determined by a technical and economic calculation, taking into account specific operating conditions, in particular, when solving issues of ensuring current collection on high-speed lines. Of particular interest is a bimetallic wire (Fig. 8.13), suspended mainly on the receiving and departure tracks of stations, as well as a combined steel-aluminum wire (the contact part is steel, Fig. 8.14).

During operation, wear of the contact wires occurs during current collection. There are electrical and mechanical components of wear. To prevent wire breakage due to an increase in tensile stresses, the maximum wear value is normalized (for example, for a wire with a cross-sectional area of ​​​​100 mm, the allowable wear is 35 mm2); as the wear of the wire increases, its tension is periodically reduced.
During operation, a break in the contact wire can occur as a result of the thermal effect of an electric current (arc) in the zone of interaction with another device, i.e., as a result of a wire burnout. Most often, burnouts of the contact wire occur in the following cases: over current collectors of a fixed EPS due to a short circuit in its high-voltage circuits; when raising or lowering the pantograph due to the flow of load current or short circuit through an electric arc; with an increase in contact resistance between the wire and the contact inserts of the current collector; the presence of ice; closing by the skid of the current collector of different potential branches of the insulating interface of the anchor sections, etc.
The main measures to prevent wire burnouts are: increasing the sensitivity and speed of protection against short-circuit currents; the use of a lock on the EPS that prevents the pantograph from lifting under load and forcibly turns it off when lowered; equipment of insulating interfaces of anchor sections with protective devices that contribute to extinguishing the arc in the zone of its possible occurrence; timely measures to prevent ice deposits on wires, etc.

carrier cable

Carrying cable - a wire of a chain suspension attached to the supporting devices of the contact network. A contact wire is suspended from the carrier cable with the help of strings - directly or through an auxiliary cable.
On domestic railways on the main tracks of lines electrified at direct current, copper wire with a cross-sectional area of ​​\u200b\u200b120 mm2 is mainly used as a carrier cable, and steel-copper wire (70 and 95 mm2) is used on the side tracks of stations. Abroad, on AC lines, bronze and steel cables with a cross section of 50 to 210 mm2 are also used. The tension of the cable in a semi-compensated contact suspension varies depending on the ambient temperature in the range from 9 to 20 kN, in a compensated suspension, depending on the brand of wire - in the range of 10-30 kN.

String

A string is an element of a chain contact suspension, with the help of which one of its wires (usually a contact one) is suspended from another - a carrier cable.
By design, they distinguish: link strings, composed of two or more spherically connected links of rigid wire; flexible strings made of flexible wire or nylon rope; rigid - in the form of spacers between the wires, used much less frequently; loop - from a wire or a metal strip freely suspended on the upper wire and rigidly or hingedly fixed in the string clamps of the lower (usually contact); sliding strings attached to one of the wires and sliding along the other.
On domestic railways e. the most widely used link strings made of bimetallic steel-copper wire with a diameter of 4 mm. Their disadvantage is electrical and mechanical wear in the joints of individual links. In the calculations, these strings are not considered as conductive. Flexible strings made of copper or bronze stranded wire, rigidly attached to string clamps and acting as electrical connectors distributed along the contact suspension and not forming significant concentrated masses on the contact wire, which is typical for typical transverse electrical connectors used in link and other non-conductive strings. Sometimes non-conductive contact suspension strings made of nylon rope are used, for fastening of which transverse electrical connectors are required.
Sliding strings capable of moving along one of the wires are used in semi-compensated catenary contact hangers with a low structural height, when installing sectional insulators, at anchoring points of a carrier cable on artificial structures with limited vertical dimensions, and in other special conditions.
Rigid strings are usually installed only on the overhead arrows of the contact network, where they act as a limiter for lifting the contact wire of one suspension relative to the wire of another.

reinforcing wire

Reinforcing wire - a wire electrically connected to the contact suspension, which serves to reduce the overall electrical resistance of the contact network. As a rule, the reinforcing wire is suspended on brackets on the field side of the support, less often - above the supports or on consoles near the carrier cable. The reinforcing wire is used in sections of direct and alternating current. The decrease in the inductive resistance of the AC contact network depends not only on the characteristics of the wire itself, but also on its placement relative to the wires of the contact suspension.
The use of a reinforcing wire is provided at the design stage; as a rule, one or more stranded wires of type A-185 are used.

electrical connector

Electrical connector - a piece of wire with conductive fittings, designed for electrical connection of wires of the contact network. There are transverse, longitudinal and bypass connectors. They are made of uninsulated wires so that they do not interfere with the longitudinal movement of the wires of contact suspensions.
Cross connectors are installed for parallel connection of all wires of the contact network of the same path (including reinforcing ones) and at stations for contact suspensions of several parallel paths included in one section. Cross connectors are mounted along the path at distances depending on the type of current and the share of the cross section of the contact wires in the total cross section of the wires of the contact network, as well as on the operating modes of the EPS on specific traction arms. In addition, at the stations, the connectors are placed in the places of starting and acceleration of the EPS.
Longitudinal connectors are installed on overhead arrows between all wires of contact suspensions that form this arrow, at the junctions of the anchor sections - on both sides with non-insulating mates and on the one hand with insulating mates and in other places.
Bypass connectors are used in cases where it is required to replenish the interrupted or reduced cross-section of the contact suspension due to the presence of intermediate anchorings of reinforcing wires or when insulators are included in the supporting cable for passing through an artificial structure.

Contact network fittings

Contact network fittings - clamps and parts for connecting the wires of the contact suspension to each other, with supporting devices and supports. The fittings (Fig. 8.15) are divided into tension (butt, end clamps, etc.), suspension (string clamps, saddles, etc.), fixing (fixing clamps, holders, lugs, etc.), conductive, mechanically lightly loaded (clamps supply, connecting and transitional - from copper to aluminum wires). The products that make up the fittings, in accordance with their purpose and production technology (casting, cold and hot stamping, pressing, etc.), are made of ductile iron, steel, copper and aluminum alloys, and plastics. The technical parameters of the fittings are regulated by regulatory documents.

Electric rail transport is the most productive, economical and environmentally friendly. Therefore, from the middle of the 20th century to the present, active work has been carried out to transfer railways to electric traction. Currently, more than 50% of Russian railways are electrified. In addition, even non-electrified sections of railways are in need of electrical energy: it is used to ensure the functioning of signaling systems, centralization, communications, lighting, computer technology, etc.

Electricity in Russia is generated by enterprises in the energy industry. Railway transport consumes about 7% of the electricity produced in our country. It is spent on providing train traction and powering non-traction consumers, which include railway stations with their infrastructure, locomotive, wagon and track facilities, as well as train traffic control devices. Small enterprises and settlements located near it can be connected to the railway power supply system.

According to Clause 1 of Appendix No. 4 to the PTE in railway transport, a reliable power supply of electric rolling stock, signaling devices, communications and computer technology should be provided as consumers of electric energy of category I, as well as other consumers in accordance with the category established for them.

consists of external network (power plants, transformer substations, power lines) and internal networks (traction network, power supply lines for signaling and communication devices, lighting network and etc.).

A three-phase variable is generated electricity voltage 6...21 kV, frequency 50 Hz. To transmit electrical energy to consumers, the voltage is not increased to 250 ... 750 kV and transmitted over long distances using ( power lines). Near the places of electricity consumption, the voltage is reduced to 110 kV with the help of and fed into the regional networks, to which, along with other consumers, electrified railways are connected and supply non-traction consumers, the current of which is supplied by a voltage of 6 ... 10 kV.

designed to provide electrical energy to electric rolling stock. It consists of contact and rail wires, which are respectively nourishing and suction line. The sections of the traction network are divided into sections (partition) and connected to neighboring ones. This makes it possible to load substations and the contact network more evenly, which generally helps to reduce electricity losses in the traction network.

On Russian railways, two traction current systems are used: permanent and single-phase variable.

On the railroads electrified with direct current, perform two functions: they lower the voltage of the supplied three-phase current using and convert it to DC using. From the traction substation electricity through the protective quick release switch is fed into the contact network by - feeder, and from the rails it returns back to the traction substation along.

Main shortcomings of the DC power supply system are its constant polarity, relatively low voltage in the contact wire and current leakage due to the inability to provide complete electrical insulation of the upper track structure from the lower one (""). The rails, which serve as current conductors of one polarity, and the subgrade are a system in which an electrochemical reaction is possible, leading to metal corrosion. As a result, the service life of rails and metal structures located near the railway track is reduced. To reduce this effect, special protective devices are used - cathode stations and anode earthing switches.

Due to the relatively low voltage in the DC system to obtain the required power of traction rolling stock ( W=UI) a large current must flow through the traction network. To do this, traction substations are placed close to each other (every 10 ... 20 km) and the cross-sectional area is increased, sometimes using double and even triple contact wire.

At AC electrification the required power is transmitted through the contact network at a higher voltage ( 25 kV) and, accordingly, lower current strength compared to a direct current system. Traction substations in this case are located at a distance of 50...70 km from each other. Their technical equipment is simpler and cheaper than DC traction substations (there are no rectifiers). In addition, the cross section of the wires of the contact network is approximately two times smaller, which can significantly save expensive copper. However, the design of locomotives and AC electric trains is more complicated and their cost is higher.

The docking of contact networks of lines electrified at direct and alternating current is carried out at special railway stations -. Such stations have electrical equipment that allows both direct and alternating current to be supplied to the same sections of the station tracks. The operation of such devices is interconnected with the operation of centralization and signaling devices. The installation of docking stations requires large investments. When the creation of such stations seems impractical, two-system and operating on both types of current are used. When using such an EPS, the transition from one type of current to another can occur while the train is moving along the haul.

Contact network- this is a set of wires, supporting structures and other equipment that ensures the transmission of electrical energy from traction substations to electric rolling stock. The main requirement for the design of the contact network is to ensure reliable permanent contact of the wire with the current collector, regardless of the speed of trains, climatic and atmospheric conditions. There are no duplicated elements in the contact network, so its damage can lead to a serious violation of the established train schedule.

In accordance with the purpose of electrified tracks, they use simple and chain air contact suspensions. On secondary station and depot tracks at a relatively low speed, it can be used (" tram" type), which is a freely hanging stretched wire, which is fixed with insulators on supports located at a distance of 50 ... 55 m from each other.

At high speeds, the sagging of the contact wire should be minimal. This is ensured by the design in which the contact wire between the supports is attached to carrying cable using frequently spaced wire strings. Due to this, the distance between the surface of the rail head and the contact wire remains almost constant. For a chain suspension, unlike a simple one, fewer supports are required: they are located at a distance of 65 ... 70 m from each other. On high-speed sections, they are used, in which a auxiliary wire, to which a contact wire is also attached with strings. In the horizontal plane, the contact wire is located relative to the track axis with a deviation of ±300 mm at each support. This ensures its wind resistance and uniform wear of the contact plates of current collectors. To reduce the sagging of the contact wire during seasonal temperature changes, it is pulled to the supports, which are called, and suspended from them through the system. The greatest length of the section between the anchor supports ( anchor section) is set taking into account the permissible tension of the worn contact wire and reaches 800 m on straight sections of the track.

The contact wire is made from hard-drawn electrolytic copper section 85 , 100 or 150 mm 2. For the convenience of attaching wires with clamps, use MF.

For reliable operation of the contact network and ease of maintenance, it is divided into separate sections - sections via air gaps and neutral inserts, as well as.

When the current collector of the electric rolling stock passes along it, with its skid, it briefly electrically connects both sections of the contact network. If, according to the power conditions of the sections, this is unacceptable, then they are separated, which consists of several consecutive air gaps. The use of neutral inserts is mandatory on lines electrified on alternating current, because. neighboring sections of the contact network can be powered by different phases coming from the power plant, the electrical connection of which with each other is unacceptable. The EPS must follow in the run-down mode and with the auxiliary machines turned off. To protect the places of sectioning of the contact network, special signal signs "" are used, installed on the supports of the contact network.

Connection or disconnection of sections is carried out by means of a contact network placed on the supports. Disconnectors can be controlled remotely using a pole-mounted electric drive connected to the energy manager console, or manually using manual drive, .

The scheme for equipping station tracks with contact wires depends on their purpose and type of station. Above the turnouts, the contact network has the so-called, formed by the intersection of two contact suspensions.

On mainline railways, they use contact network supports. The distance from the axis of the extreme path to the inner edge of the supports on straight sections must be at least 3100 mm. In special cases, on electrified lines, it is allowed to reduce the specified distance to 2450 mm- at stations and before 2750 mm- on the run. On hauls, they are mainly used individual cantilever suspension of contact wire. At stations (and in some cases, on hauls), it is applied group suspension of contact wires on and crossbars.

To protect the contact network from short circuit between adjacent traction substations are equipped with safety switches. All metal structures directly interacting with elements of the contact network or located within a radius of 5 m from them, ground(connected to the rails). On lines electrified at direct current, special diode and spark are used. To protect the elements and equipment of the contact network from overvoltage (for example, due to a lightning strike), some supports are installed with arc horns.

For electrical insulation of contact network elements that are under voltage (contact wire, carrier cable, strings, clamps) from grounded elements (supports, consoles, crossbars, etc.) are used. According to the functions performed, insulators are suspended, tension, fixative, console, by design - dish-shaped and rod, and according to the material from which they are made -, and.

On electrified railways, the rails run reverse traction current. To reduce power losses and ensure the normal operation of automation and telemechanics devices on such lines, the following features of the structure of the track structure are provided:

• to the rail heads from the outside of the track are welded (shunts), which reduce the electrical resistance of the rail joints;
• the rails are isolated from the sleepers with the help of rubber gaskets in the case of reinforced concrete sleepers and impregnation of wooden sleepers with creosote;
• crushed stone ballast is used, which has good dielectric properties, and a gap of at least 3 cm is provided between the rail sole and the ballast;
• on lines equipped with automatic blocking and electrical interlocking, insulating joints are used, and in order to pass traction current around them, they install or frequency filters.

One of the ways of joining lines electrified on different types of current is the sectioning of the contact network with the switching of individual sections to be powered by DC or AC feeders. The contact network of docking stations has groups of isolated sections: direct current, alternating current and switchable. The switched sections are supplied with electricity through. The contact network from one type of current to another is switched with special motor drives installed at the grouping points. Two supply lines are connected to each point: AC and DC from the DC-AC traction substation. Feeders of the appropriate type of current of this substation are also connected to the contact network of the necks of the docking station and adjacent hauls.

To exclude the possibility of supplying current to individual sections of the contact network that does not correspond to the rolling stock located there, as well as the exit of the EPS to sections of the contact network with a different current system, the switches are blocked with each other and with devices electrical centralization . Switch control include single system route-relay centralization of control of arrows and station signals. The station attendant, collecting any route, simultaneously with the installation of arrows and signals in the required position, makes the appropriate switching in the contact network.

Route centralization at docking stations has a system for counting the arrival and departure of electric rolling stock on the track sections of the switched sections of the contact network, which prevents it from being energized by another kind of current. To protect the equipment of power supply devices and electric rolling stock of direct current in case of contact with them as a result of any disturbances in the alternating current voltage, there is special equipment.

Power supply devices must provide reliable power supply:

• electric rolling stock for the movement of trains with established weight norms, speeds and intervals between them with the required movement sizes;
• signaling devices, communications and computer technology as consumers of electrical energy of category I;
• all other consumers of railway transport in accordance with the established category.

To power supply devices for traction rolling stock the requirements described above are imposed with respect to and .

Backup power supply sources for signaling devices must be in constant readiness and ensure uninterrupted operation of signaling devices and crossing signaling for at least 8 hours, provided that the power has not been turned off in the previous 36 hours.

To ensure reliable power supply, periodic monitoring of the state of structures and power supply devices, measurement of their parameters, diagnostic devices, and scheduled repairs should be carried out.

Power supply devices must be protected from short circuit currents, overvoltages and overloads in excess of established standards.

Metal underground structures (pipelines, cables, etc.), as well as metal and reinforced concrete structures located in the area of ​​lines electrified at direct current, must be protected from electrical corrosion.

Within artificial structures, the distance from the current-carrying elements of the current collector and parts of the contact network under voltage to the grounded parts of structures and rolling stock must be at least 200 mm on lines electrified at direct current, and not less than 270 mm- on alternating current.

For the safety of maintenance personnel and other persons, as well as to improve protection against short circuit currents, they ground or equip with residual current devices metal supports and elements to which the contact network is suspended, as well as all metal structures located closer than 5 m from parts of the contact network, under tension.

Karelin Denis Igorevich ® Orekhovo-Zuevsky Railway College named after V.I. Bondarenko "2017

POWER SUPPLY DEVICES

AT system of electrified railways in Russia(Fig. 1) includes structures and devices that make up its external part (thermal, hydraulic and nuclear power plants, power lines) and the traction part (traction substations, contact network, rail circuit, supply and suction lines).

Fig. 1 “General view of an electrified direct current railway and its power supply devices: 1- power plant; 2 - step-up transformer; 3 - high-voltage switch; 4 - power line; 5 - traction substation; 6 - block of high-speed switches and disconnectors; 7 - suction line; 8 - supply line; 9 - rectifier; 10 – traction transformer; 11 - high-voltage switch; 12 - discharger.

power plants generate a three-phase current with a voltage of 220-380 V, which is then increased at substations for transmission over long distances.

Near places where electricity is consumed, the voltage is reduced by transformer substations up to 220 kV and are fed into the district high voltage networks, to which consumers of electricity are connected, including traction substations of electrified railways that feed the contact network.

electrified railways Russians operate on direct or single-phase alternating current.

Relatively low voltage is the main disadvantage of the DC system. To maintain the desired voltage level at the current collectors of locomotives, traction substations are placed at a distance of 10-25 km. On lines with high traffic density and heavy passenger traffic, it is necessary not only to reduce the distance between substations, but also to increase the cross section of the contact network (an additional contact wire is suspended).

AC traction substations serve only to lower the AC voltage received from the mains to 27.5 kV.

Contact network is designed to transfer electrical energy received from traction substations to electric rolling stock and must provide reliable current collection at the highest speeds in any atmospheric conditions.

There are different designs of contact network for ground electric transport and subways. On our railways, a design is adopted (Fig. 2), the main elements of which are supports; contact suspension, consisting of a carrier cable, contact and reinforcing wires; consoles, clamps, etc.

Fig. 2 The device of the contact network on a double-track stage: 1 - carrying cable; 2 - contact wire; 3 - reinforcing wire; 4 - string; 5 - retainer; 6 - console; 7 - support.

Fig.3 Single chain suspension: 1 - console; 2 - carrying cable; 3 - strings; 4 - insulator; 5 - contact wire; 6 - latch.

Reinforced concrete or metal supports located along the railway track at a distance of 65-80 m from each other.

The consoles are fixed at the top of the supports. A copper or bimetallic carrying cable is suspended from them on insulators.

contact wire made of copper and suspended with strings from a bimetallic or copper carrier cable. The distance between the strings is usually 6-12 m.

On straight sections of the track, the contact wires are located in a zigzag pattern relative to the axis of the track by 300 mm in each direction (Fig. 4). This is necessary to ensure uniform wear of the pantograph pads of the electric rolling stock.

Fig.4 Location of the contact wire in straight sections

This arrangement of the contact wire is carried out with the help of clamps placed on each support. The clamps also prevent the contact network from swinging from the side wind.

To reduce the sag of the contact wire during seasonal temperature changes, it is pulled to the supports, which are called anchors, and cargo expansion joints are suspended from them through a system of blocks and insulators (Fig. 5.).

Fig.5 Conjugation of anchor sections: 1.4 - anchor supports; 2,3 - transitional supports; I, II - contact hangers of mating anchor sections

The height of the contact wire suspension above the level of the top of the rail head must be at least 5750 mm and not exceed 6800 mm.

For reliable operation of the contact network and ease of maintenance, it is divided into separate sections (sections) using air gaps and neutral inserts (insulating mates), as well as sectional and mortise insulators.

When the current collector of the electric rolling stock passes through the air gap, it briefly electrically connects both sections of the contact network. If, according to the power conditions of the sections, this is unacceptable, then they are separated by a neutral insert, which consists of several gaps connected in series (Fig. 6).

Fig.6 Neutral insert: 1 - additional contact suspension; 2,3 - sectional disconnectors; 4.5 - warning signals; I, II - contact hangers of mating anchor sections.

The use of such inserts is necessary in alternating current sections, when adjacent sections are powered by different phases of a three-phase current. The length of the neutral insert is set in such a way that, at any position of the raised pantographs of the electric rolling stock, the simultaneous closure of the contact wires of the neutral insert with the wires of the sections of the contact network adjacent to it is completely excluded.

3.2 RAILWAY POWER SUPPLY MANAGEMENT AND POWER SUPPLY ENTERPRISE

The management of the power supply industry of all railways and industrial enterprises of railway transport is carried out by Department of Electrification and Power Supply of Russian Railways. The main tasks of the Department are to ensure the uninterrupted operation of power supply devices, the development of the power supply base, and the development of plans for the electrification of railways.

The Department carries out operational and technical management of railway power supply services, the most important task of which is the uninterrupted supply of electrical energy to electrified sections of the road and to consumers of electrical energy in all sectors of the road economy, as well as to all other consumers connected to the power grids of the road.

Services carry out their activities through linear enterprises - power supply distances.

AT power supply distance functions includes:

Reception of electrical energy from the unified electrical network of the country and its supply to the contact network;