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Details and dimensions of the contact network. Contact network devices. Upon arrival at the place of work, conduct a current safety briefing with a signature for everyone in the outfit

Toolkit

To carry out practical exercises

In the discipline "Contact Network".

1. Selection of parts and materials for contact network nodes.

2. Determination of loads acting on the wires of the contact network.

3. Selection of standard consoles and clamps for a given support arrangement.

4. Calculation of the bending moment acting on the support and selection of a typical intermediate support.

5. Preparation of operational and technical documentation during work on the contact network.

6. Preparation of operational and technical documentation during the execution of work on the contact network.

7. Checking the technical condition, adjusting and repairing the air needle.

8. Checking the condition, adjusting and repairing the sectional insulator.

9. Checking the condition, adjusting and repairing the sectional disconnector.

10. Checking the condition, adjusting and repairing arresters of various types.

11. Checking the condition, adjusting and repairing the insulating interface.

12. Mechanical calculation of the anchor section of the catenary chain suspension.

13. Determination of the tension of a loaded support cable.

14. Calculation of sag arrows and construction of installation curves of the supporting cable and contact wire.

15. Drawing up a list of necessary materials, supporting and fixing devices for the contact network of the stage.

Explanatory note.

The methodological manual contains options for practical classes in the discipline “Contact Network”. The purpose of the classes is to consolidate the knowledge acquired in the theoretical course of the discipline, acquire practical skills in checking the condition and adjusting individual nodes of the contact network, and skills in using technical literature. The topic of the proposed practical classes was chosen in accordance with the work program of the discipline and the current standard of specialty 1004.01 “Power supply in railway transport”.

To carry out classes in the “Contact Network” classroom, you must have the basic elements of the contact network or their models, stands, the necessary posters, photographs, measuring and adjusting tools.

In a number of works, for better memorization and assimilation of the material, it is proposed to depict individual nodes of the contact network, describe their purpose and requirements for them.

When performing practical exercises, students must use reference, normative and technical literature.

You should pay attention to safety measures that ensure the safety of maintenance and repair work on overhead contact network devices.

Practical lesson No. 1

Selection of parts and materials for contact network nodes.

Purpose of the lesson: learn how to practically select parts for a given catenary system.

Initial data: type of catenary chain, catenary chain unit (set by the teacher according to tables 1.1, 1.2).

Table 1.1. Types of contact suspensions.

Option number	Support cable	Contact wire	Current system	Suspension type
side path
-	PBSM-70	MF-85	constant variable	KS 70
Main way
	M-120	BrF-100	constant	KS 140
	M-95	MF-100	constant	KS 160
	M-95	2MF-100	constant	KS 120
	M-120	2MF-100	constant	KS 140
	M-120	2MF-100	constant	KS 160
	PBSM-95	NlF-100	variable	KS 120
	M-95	BrF-100	variable	KS 160
	PBSM-95	BrF-100	variable	KS 140
	M-95	MF-100	variable	KS 160
	PBSM-95	MF-100	variable	KS 140

Table 1.2. Catenary chain assembly.

Brief theoretical information:

When choosing a support unit for a catenary chain and determining the method of anchoring the wires of a catenary chain, it is necessary to take into account the speeds of trains on a given section and the fact that the higher the speed of trains, the greater the elasticity of the catenary chain.

Contact network fittings are a set of parts intended for fastening structures, fixing leads and cables, and assembling various components of a contact network. The fittings must have sufficient mechanical strength, good compatibility, high reliability and the same corrosion resistance, and for high-speed current collection - also a minimum weight.

All parts of contact networks can be divided into two groups: mechanical and conductive.

The first group includes parts designed for purely mechanical loads. This includes: a wedge clamp, a collet clamp for a support cable, saddles, fork thimbles, split and continuous lugs, etc.

The second group includes parts designed for mechanical and electrical loads. This includes: collet butt clamps for joining the supporting cable, oval connectors, butt clamps for contact wire, string, connecting and transition clamps. According to the material of manufacture, fittings are divided into cast iron (malleable or gray cast iron), steel, non-ferrous metals and their alloys (copper, bronze, aluminum, brass).

Products made of cast iron have a protective anti-corrosion coating - hot-dip galvanizing, and products made of steel - electrolytic galvanizing followed by chrome plating.

Procedure for completing the practical lesson:

1. Select a support node for a given catenary and sketch it with all geometric parameters (L.1, p. 80).

2. Select the material and cross-section of wires for simple and spring strings of the support unit.

3. Select parts for a given unit using L.9 or L10 or L11.

Enter the selected details into Table 1.3.

4. Select a part for joining the contact wire and connecting the support cable. Enter the selected details into Table 1.3.

Table 1.3. Parts for catenary units.

5. Describe the purpose and installation location of longitudinal and transverse electrical connectors.

6. Describe the purpose of non-isolating interfaces. Draw a diagram of a non-insulating interface and indicate all the main dimensions.

7. Prepare a report. Draw conclusions based on the completed lesson.

Control questions:

1. What loads do the contact network parts take?

2. What determines the choice of the type of support unit for a catenary chain?

3. In what ways can the elasticity of a catenary chain be made uniform?

4. Why can materials that are not highly conductive be used for load-bearing cables?

5. Formulate the purpose and types of middle anchors.

6. What determines the method of attaching the supporting cable to the supporting structure?

Fig.1.1. Anchoring of a compensated AC catenary suspension ( A) and permanent ( b) current:

1- anchor guy; 2- anchor bracket; 3, 4, 19 – steel compensator cable with a diameter of 11 mm, length, respectively, 10, 11, 13 m; 5- compensator block; 6- rocker arm; 7- rod “eye-double eye” 150 mm long; 8- adjustment plate; 9- insulator with pestle; 10- insulator with earrings; 11- electrical connector; 12- rocker arm with two rods; 13, 22 - clamp, respectively, for 25-30 loads; 15- reinforced concrete load; 16- load limiter cable; 17- load limiter bracket; 18- mounting holes; 20- pestle-eye rod, 1000 mm long; 21- rocker arm for attaching two contact wires; 23-bar for 15 loads; 24- limiter for a single garland of weights.

Fig. 1.2.Anchoring of a semi-compensated AC chain suspension with a two-block compensator ( A) and direct current with a three-block compensator ( b):

1- anchor guy; 2- anchor bracket; 3- rod “pestle-double eye” 1000 mm long; 4- insulator with pestle; 5- insulator with earring; 6- steel compensator cable with a diameter of 11 mm; 7- compensator block; 8- pestle-eye rod, 1000 mm long; 9- bar for weights; 10- reinforced concrete load; 11- limiter for a single garland of weights; 12- load limiter cable; 13- load limiter bracket; 14- steel compensator cable with a diameter of 10 mm and a length of 10 m; 15- clamp for weights; 16- limiter for a double garland of weights; 17- rocker for anchoring two wires.

Fig.1.3. Average anchorage compensated ( hell) and semi-compensated ( e) catenary chains; for a single contact wire ( b), double contact wire ( G); on an isolated console ( V) and on a non-isolated console ( d).

Federal Agency for Railway Transport.

Irkutsk State Transport University.

Department: ECT

COURSE PROJECT

Option-83

Discipline: “Contact networks”

“Calculation of the section of the contact network of the station and section”

Completed by: student Dobrynin A.I.

Checked by: Stupitsky V.P.

Irkutsk

Initial data.

1. Characteristics of chain suspension

On the main haulage and station tracks, the chain suspension is semi-compensated.

With two contact wires, the distance between them is assumed to be 40 mm.

Catenary type: M120 + 2 MF – 100;

Type of current: constant;

2. Meteorological conditions

Climatic zone: IIb;

Wind region: I;

Icy region: II;

Ice has a cylindrical shape with a density of 900 kg/m3;

Temperature of ice formations t = -5 0 C;

Temperature at which the wind of maximum intensity is observed t = +5 0 C;

3. Station

All tracks at the station are electrified, except for the access track to the traction substation. The arrows adjacent to the main track are 1/11 grade (there is one meter of lateral deviation per eleven meters of track length), the remaining arrows are 1/9 grade.

The numbers on the diagram indicate the distances from the axis of the passenger building (in meters) to the points of the arrows, entrance traffic lights, dead ends and pedestrian bridges, and also indicate the distances between adjacent tracks.

4. Driving

The stretch is specified in the form of a picket of main objects: input signals, curves with corresponding radii, bridges and other artificial structures. The compatibility of the section with the station is checked by the picketage of the common input signal.

Picketing of the main transportation facilities

Input signal of a given station 23 km 8+42;

Beginning of the curve (center left) R = 600 m 2 + 17;

End of curve 5+38;

Stone pipe axis with hole 1.1 m 5+94;

Beginning of curve (center right) R = 850 m 7+37;

End of curve 25 km 4+64;

Bridge over the river with a ride below:

axle 7+27;

bridge length, m 130;

Axle of reinforced concrete pipe with a hole of 3.5 m 9+09;

Beginning of curve (center left) R = 1000 m 26 km 0+22;

End of curve 4+30;

Input signal of the next station 27 km 7+27;

Crossing axis 6 m wide 7+94;

The first arrow of the next station is 9+55.

1. The height of the bridge over the river is 6.5 m (the distance from the UGR to the bottom of the wind connections of the bridge);

2. On the right, along the kilometers, it is planned to lay a second track;

3. At a distance of 300 m on both sides of the bridge over the river, the path is located on an embankment 7 m high.

Introduction

A set of devices, starting from power station generators and ending with the traction network, makes up the power supply system for electrified railways. This system supplies electrical energy, in addition to its own electric traction (electric locomotives and electric trains), as well as all non-traction railway consumers and consumers in adjacent territories. Therefore, electrification of railways solves not only the transport problem, but also contributes to solving the most important national economic problem - electrification of the entire country.

The main advantage of electric traction over autonomous traction (those with energy generators on the locomotive itself) is determined by the centralized power supply and boils down to the following:

The production of electrical energy at large power plants leads, like any mass production, to a decrease in its cost, an increase in efficiency and a decrease in fuel consumption.

Power plants can use any type of fuel and, in particular, low-calorie fuels that are not transportable (the cost of transportation of which is not justified). Power plants can be built directly at the place of fuel extraction, as a result of which there is no need for its transportation.

For electric traction, hydropower and energy from nuclear power plants can be used.

With electric traction, energy recovery (return) during electric braking is possible.

With a centralized power supply, the power required for electric traction is practically unlimited. This makes it possible in certain periods to consume such power that cannot be provided on autonomous locomotives, which makes it possible, for example, to realize significantly higher speeds on heavy climbs with large train weights.

An electric locomotive (electric locomotive or electric car), unlike autonomous locomotives, does not have its own energy generators. Therefore, it is cheaper and more reliable than an autonomous locomotive.

An electric locomotive does not have parts that operate at high temperatures and with reciprocating motion (as on a steam locomotive, diesel locomotive, gas turbine locomotive), which reduces the cost of repairing the locomotive.

The advantages of electric traction created by centralized power supply require the construction of a special power supply system for their implementation, the costs of which, as a rule, significantly exceed the costs of electric rolling stock. The reliability of electrified roads depends on the reliability of the power supply system. Therefore, issues of reliability and efficiency of the power supply system significantly affect the reliability and efficiency of the entire electric railway as a whole.

Contact network devices are used to supply electricity to rolling stock.

The catenary network project, which is one of the main parts of the railway section electrification project, is carried out in compliance with the requirements and recommendations of a number of governing documents:

Instructions for the development of projects and estimates for industrial construction;

Temporary instructions for the development of projects and estimates for railway construction;

Norms for technological design of railway electrification, etc.

At the same time, the requirements given in the documents regulating the operation of the contact network are taken into account: the rules for the technical operation of railways, the rules for maintaining the contact network of electrified railways.

In this course project, a section of a single-phase direct current contact network was calculated. Installation plans for the contact network of the station and section have been drawn up.

Catenary network devices include all wires of catenary suspensions, supporting and fixing structures, supports with parts for fastening in the ground; overhead line devices include wires of various lines (supply, suction, for power supply of automatic blocking and other non-traction consumers, etc.) and structures for mounting them on supports.

The devices of the contact network and overhead lines, exposed to various climatic factors (significant temperature changes, strong winds, ice formations), must successfully withstand them, ensuring the uninterrupted movement of trains with established weight standards, speeds and intervals between trains at the required traffic volumes. In addition, under operating conditions, wire breaks, shocks to current collectors and other impacts are possible, which also need to be taken into account during the design process.

The contact network has no reserve, which places increased demands on the quality of its design.

When designing a contact network in the section of the railway section electrification project, the following is established:

Design conditions – climatic and engineering-geological;

Catenary type (all calculations to determine the required cross-sectional area of the overhead wires are performed in the power supply section of the project);

The length of the spans between the contact network supports on all sections of the route;

Types of supports, methods of fixing them in the ground and types of foundations for those supports that require them;

Types of supporting and fixing structures;

Power supply and partitioning circuits;

Scope of work on installing supports at hauls and stations;

Basic provisions for organizing construction and operation.

Source data analysis

With a double contact wire, a compensated contact suspension is used in areas with train speeds of 120 km/h or more. On the main tracks of the station, due to reduced speeds, as a rule, a semi-compensated chain suspension is used. Based on these meteorological conditions, we select the main climatic parameters that repeat once every ten years:

Temperature range from table. 2.с3: -30 0 С ¸ 45 0 С;

Maximum wind speed from table. 5.s14: v nor = 29 m/s;

Ice wall thickness from table. 1.с12: b =10 mm;

Depending on the operating conditions and the nature of the electrified area, the necessary correction factors for wind gusts and ice intensity are selected. For the general case, we accept their values as 0.95, 1.0 and 1.25, respectively, for the station, stage and embankment.

Determination of loads acting on overhead wires

For station and stage.

Calculation of vertical loads

The most unfavorable operating conditions for individual overhead network structures can occur under various combinations of meteorological factors, which can consist of four main components: minimum air temperature, maximum intensity of ice formations, maximum wind speed and maximum air temperature.

The load from its own weight of 1 m of overhead contact suspension is determined from the expression:

where is the load from the dead weight of the supporting cable, N/m;

The same but for the contact wire, N/m;

The same, but from strings and clamps, is taken equal to 1

Number of contact wires.

If there is no data in the directory, the load from the wire’s own weight can be determined from the expression:

, N/m (2)

where is the cross-sectional area of the wire, m2;

Wire material density, kg/m 3 ;

Coefficient taking into account the design of the wire (for a solid wire = 1, for a multi-wire cable = 1.025);

For combined wires (AC, PBSM, etc.), the load from their own weight can be determined from the expression:

where , is the cross-sectional area of wires made of materials 1 and 2, m2;

Density of materials 1 and 2, kg/m3.

For suspension M120 + 2 MF – 100:

According to expression (1) we get:

The load from the weight of ice per meter of wire or cable with a cylindrical form of its deposition is determined by the formula:

where is the density of ice 900 kg/m 3 ;

Thickness of the ice layer wall, m

Wire diameter, m.

Considering that the product is 9.81×900×3.14 = 27.7×10 3, we can write:

We define the calculated value of the thickness of the ice layer as , where is the thickness of the ice layer in accordance with the ice-covered region b = 10 mm; KG is a coefficient that takes into account the actual diameter of the wire and the height of its suspension. For the station and section K G = 0.95.

According to expression (5), we determine the weight of ice per 1 m of support cable

The thickness of the ice wall on the contact wire, taking into account its removal by operating personnel and current collectors, is reduced by 50% compared to the supporting cable. The calculated diameter of the contact wire is taken averaged from the height and width of its cross-section:

where H is the height of the wire cross-section, m; A – wire cross-section width, m;

Using expression (6) we get:

mm.

Using expression (5) we determine the weight of ice per 1 m of contact wire

The weight of ice on the strings is not taken into account. Then the total weight of 1 m of chain suspension with ice is determined by the formula:

where g is the weight of the catenary N/m;

g GN – weight of ice per 1 m of support cable, N/m;

g GK – weight of ice per 1 m of contact wire, N/m.

According to expression (7), the total weight of 1 m of chain suspension with ice:

We determine horizontal loads.

The wind load on the wire in the maximum wind mode is determined by the formula:

(8)

where is the air density at temperature t = +15 0 C and atmospheric pressure 760 mm Hg. It is taken equal to 1.23 kg/m3;

v P - design wind speed, m/s; v P = 29 m/s.

С Х – aerodynamic drag coefficient, depending on the shape and position of the surface of the object, for a station and section С Х =1.20 for one wire С Х =1.25;

KV is a coefficient that takes into account the actual diameter of the wire and the height of its suspension. For the station and section KV = 0.95.

d i - wire diameter (for contact wires - vertical cross-sectional size), mm.

The wind load on the wire in the presence of ice on the wire is determined by the formula:

where is the estimated wind speed during ice conditions (according to Table 1.4), m/s;

For determination on the contact wire, the value is taken equal to b/2.

We determine the resulting loads on the n/t for two modes.

Resulting loads on an individual wire in the absence of ice:

If there is ice:

Calculation of span lengths

Calculation of wire tension

The maximum permissible tension of the supporting cable is determined by the formula

where is a coefficient taking into account the spread of mechanical characteristics of individual wires, 0.95;

Tensile strength of wire material, Pa;

Safety factor;

S - calculated cross-sectional area, m2.

The maximum permissible and nominal tension for wires is in Table 10.

Determination of maximum permissible span lengths

where K is the tension of the contact wire, N;

Equivalent load on the contact wire from the supporting cable, N/m.

where is the permissible deviation of the contact wire from the track axis. On a straight section 0.5 m, on a curve 0.45 m;

Zigzags of the contact reins on adjacent supports. On a straight section of the path +/-0.3 m. On a curved section +/-0.4 m.

Deflection of a support under the influence of wind at the level of the supporting cable and contact wire. These values (depending on wind speed) are given on page 48.

Zigzag contact wire, identical in size on adjacent supports.

Let us assume that zigzags on adjacent supports on a straight section are directed in one direction, and on a curve in different directions.

where is the tension of the supporting cable in the wind mode of maximum intensity, N;

Span length, m;

The height of the insulator garland. In the project we accept 4 PS-70E. The height of one cup is 0.127 m.

Average string length at mid-span at design height h0, m.

Calculation for the direct section of the track at the station (side tracks):

The resulting length differs from the previous calculation by less than 5 m, therefore it can be considered finally accepted.

On a curved section of the path, the maximum permissible span length is determined from the expression:

The calculation of the maximum permissible span length is performed:

For the direct section: station (main and side tracks) and stage (plain and embankment);

For a curved section: on a stretch for plains and embankments at given radii of curvature.

The resulting length differs from the previous calculation by less than 5 m, therefore it can be considered finally accepted.

We summarize all calculations in a table

Place of settlement	Span length without Р e	Span length with Р e	Final span length
1. direct station and stage	51.2	49.6	50
2. direct stretch on the embankment	45.2	43.8	45
3. curve R 1 =600m	37.8	37.3	37
4. curve R 2 =850m	42.3	41.8	42
5. curve R 3 =1000m	44.4	43.8	44
6. curve R 6 =850m on the embankment	42.0	41.4	42
7. curve R 5 =1000 m on the embankment	44.07	43.4	44
7. curve R4=600 m on the embankment	37.5	37.1	37

The procedure for drawing up a station and section plan

The procedure for drawing up a station plan.

Preparation of a station plan. We draw the station plan at a scale of 1:1000 on a sheet of graph paper. The required length of the sheet is determined in accordance with the given station diagram, which indicates the distances of all centers of turnouts, traffic lights, dead ends from the axis of the passenger building in meters. In this case, we conventionally take these marks to the left with a minus sign, and to the right with a plus sign.

We begin drawing the station plan by marking it with thin vertical lines, every 100 meters of conditional station pickets on both sides of the axis of the passenger building, taken as the zero picket. The paths on the station plan are represented by their axes. On switches, the track axes intersect at a point called the center of the switch. Using the data on the given station diagram, we plot the axes of the tracks with parallel lines, and the distances between them must correspond on the accepted scale to the given inter-tracks.

On the station plan we also show non-electrified tracks. Having indicated the picket marks of the turnout centers on special posts, we draw turnout streets and exits. Next, on the station plan we draw buildings, a pedestrian bridge, passenger platforms, a traction substation, entrance traffic lights, and crossings.

Marking the places where it is necessary to fix the contact wires.

We start laying out the supports at the station by marking the places where it is necessary to provide devices for fixing the contact wires. Such places are all turnouts over which air switches must be mounted and all places where the wire must change its direction.

On single air switches, the best arrangement of the contact wires forming the switch is obtained if the locking device is installed at a certain distance C from the center of the switch. The displacement of the fixing supports is allowed to the center of the turnout by 1 - 2 meters and from the center of the turnout by 3 - 4 meters. At the vertex of the curve, we mark the fixing support along the picket of this vertex, and the zigzag at this support is always negative.

Arrangement of supports in station necks

We start laying out the supports at the station from the neck, where the largest number of places for fixing contact wires are concentrated. From the designated fixation points, we select those places where it is rational to install load-bearing supports. In this case, the actual lengths of the spans should not exceed the design lengths and the difference in the lengths of adjacent spans should be no more than 25% of the length of the larger one. In addition, supports on double-track sections should be located in one picket. If installing only load-bearing supports leads to a significant reduction in pickets, then the possibility of making some of the air switches non-fixed should be considered.

Non-fixed air switches can only be made on side tracks, on supports located close (up to 20 m) to the switch.

Having chosen the dimensions of the spans between the supports fixing the air switches of the main tracks, we proceed to marking the load-bearing supports on the next station switches, taking into account the requirements for span lengths listed above. We place zigzags at the fixing supports.

Arrangement of supports in the middle part of the station.

If there are artificial structures within the station, we select a method for passing the catenary through these structures. In accordance with the accepted method, we outline the installation locations for supports near the passenger building. After this, in the remaining parts of the station, using, if possible, the maximum permissible spans, we mark out places for the supports of the rigid crossbars.

The procedure for passing the suspension under artificial structures at the station.

Artificial structures are found at stages and stations of the electrified line; they often do not allow the passage of a normal type chain suspension with normal dimensions.

The method of passing the contact wire under artificial structures is chosen depending on the voltage in the contact network, the height of the artificial structure above the level of the top of the rail head (UGR), its length along the electrified tracks, and the set speed of trains.

Placing a contact wire under artificial structures with limited dimensions is associated with solving two main problems:

1. Ensuring the necessary air gaps between contact wires and grounded parts of artificial structures;

2. Selection of material, design and method of fastening supporting devices.

The cross-section of the contact wire within the artificial structure must be equal to the cross-section of the contact wire in adjacent areas, for which, if necessary, bypasses are installed to fill the cross-section of the LT and reinforcing wires.

The slopes of the contact wire on the approaches to an artificial structure are set according to the conditions of interaction between the pantograph and the contact wire, depending on the maximum speed of movement and the parameters of the catenary and pantograph.

The minimum amount of vertical space required to accommodate the current-carrying elements of the contact network when passing the suspension in the cramped conditions of existing artificial structures is 100 mm. with suspension without NT and 250mm. with NT.

In cases where, at normal voltage in the contact network, it is impossible, due to the conditions of the required overall distances for this voltage, to place a catenary without reconstructing an artificial structure, a non-insulated catenary with a device on both sides of neutral inserts is installed within the artificial structure. In this case, trains are driven through an artificial structure with the current turned off, by inertia.

In all cases when the distance from the catenary wires to the grounded parts of artificial structures located above it, under the most unfavorable conditions, is less than 500 mm. at DC and 650mm. with alternating current or there is any possibility of pressing the catenary wires to parts of the artificial structure.

neutral element

650 or less

bumper

insulators

Breakdown anchor sections

After placing the supports along the entire length of the station, we lay out the anchor sections and finally select the installation locations for the anchor supports.

When laying out anchor sections, the following requirements and conditions must be met:

The number of anchor sections should be as small as possible. In this case, the length of the anchor section should not exceed 1600 meters;

We allocate side tracks and exits between the main tracks into separate anchor sections;

For anchoring, it is advisable to use previously planned intermediate supports;

When anchoring, the wire should not change its direction by an angle of more than 7 0;

If the length of the side track is more than 1600 meters, it should be divided into two anchor sections, and a non-isolating connection should be made in the middle.

The length of several spans located approximately in the middle of the anchor section is reduced by 10% relative to the maximum in this location in order to accommodate the average anchorage.

Arrangement of supports at the ends of the station. According to the established scheme for sectioning the contact network, we carry out longitudinal sectioning at the junctions of the stages and stations. An insulating four-span interface is installed between the input signal and the station turnout closest to the section, if possible on straight sections of the track. At the same time, we reduce each transition span by 25% of the calculated one; We shift the transition supports along the first and second paths relative to each other by 5 meters.

The approach of the transition support to the entrance traffic light is allowed at a distance of at least 5 meters.

After placing the supports for the insulating junction, we break the span between the extreme arrow and the junction, then we place zigzags, the direction of which must be consistent.

If there are supports at the crossing station, we place them so that the distance from the edge of the roadway of the crossing along the train to the supports is at least 25 meters.

To perform transverse sectioning from the power supply circuit and sectioning the station, we transfer all the sectional insulators and perform their numbering, and on the transverse cables of the rigid crossbars we show the mortise insulators between the sections, which are isolated from each other.

As the main type of supporting structures of the contact network at stations, rigid crossbars should be used, covering from two to eight tracks. If there are more than eight paths, flexible crossbars can be used.

Catenary power supply and sectioning

Description of the power supply and partitioning circuit. On electrified railways, electric rolling stock receives electricity through a contact network from traction substations located at such a distance from each other as to provide reliable protection from short circuit currents.

In a direct current system, electricity enters the contact network alternately from two phases with a voltage of 3.3 kV and also returns along the track circuit to the third phase. Power supply alternation is carried out to equalize the loads of individual phases of the energy supply system.

As a rule, a two-way power supply scheme is used, in which each locomotive on the line receives energy from two traction substations. The exception is the sections of the contact network located at the end of the electrified line, where a cantilever (one-way) power supply scheme from the outermost traction substation can be used and sectioning posts are arranged along the electrified line with insulating interfaces and each section receives electricity from different supply lines (longitudinal sectioning).

When longitudinal sectioning, in addition to dividing the contact network at each traction substation and sectioning post, the contact network of each haul and station is separated into separate sections using insulating interfaces. The sections are connected to each other by sectional disconnectors, each of the sections can be disconnected by these disconnectors. The overhead line on the western side of the station, located behind the insulating junction, which separates the main tracks of the station from the stage by an air gap, is fed through the contact network feeder Fl1.

Sectional disconnectors with motor drives TU and DU, normally closed, are installed on the feeders.

The eastern section of the station is fed through feeder Fl2. Sectional disconnectors with motor drives TU and DU, normally closed, are installed on the feeders.

The main tracks of the station are fed through feeder Fl31. Equipped with a sectional disconnector with a motor drive TU and DU, normally closed.

Disconnectors A, B connect the station tracks and the stage, with motor drives on the technical equipment, are normally turned on. When cross-sectioning at stations, the contact network of groups of tracks is separated into separate sections and fed from the main tracks through sectional disconnectors, which can be turned off if necessary. Sections of the contact network at the corresponding exits between the main and side tracks are insulated with sectional insulators. This achieves independent power supply for each track and each section separately, which facilitates the protection device and makes it possible, if one of the sections is damaged or disconnected, to carry out train movement in other sections.

Tracing of supply and suction lines

We design the routes of supply and suction lines from the traction substation to the electrified tracks according to the shortest distance. To anchor the lines near the traction substation building and tracks, we use reinforced concrete supports.

Air supply and suction lines running along the station are suspended from the field side of the contact network supports. To transfer the supply lines through the tracks, we use rigid crossbars on which T-shaped structures are mounted.

Tracing the contact network on the stretch

Preparation of a haul plan. We carry out the haul plan on a sheet of graph paper on a scale of 1:2000 (sheet width 297 mm). The required length of the sheet is determined based on the specified length of the stretch, taking into account the scale of the required margin (800 mm) on the right side of the drawing for placing general data in the title block and taken as a multiple of the standard size of 210 mm.

Depending on the number of tracks on the stretch, we draw one or two straight lines on the plan (at a distance of 1 cm from each other), representing the axes of the tracks.

Pickets on the stretch are marked with vertical lines every 5 cm (100 m) and numbered in the direction of counting kilometers, starting from the input signal picket specified in the task.

If, when tracing the station contact network, in the right neck there was a four-span insulating interface between the overhead catenaries of the station and the stage, located before the input signal, then to repeat it on the stage plan, the numbering of pickets must begin 2-3 pickets before the given picket of the input signal. Above and below the straight lines representing the track axes, we place data in the form of tables along the entire stretch. Below the bottom table we draw a straight line plan.

Using marked pickets, in accordance with the project assignment, artificial structures are shown on the track plan, and on the straight line plan we show kilometer signs, the direction, radius and length of the curved section of the track, the boundaries of the location of high embankments and deep excavations, and we repeat the image of artificial structures.

Pickets of artificial structures, signals, curves, embankments, and excavations are indicated in the column “Picketage of artificial structures” of the lower table in the form of a fraction, the numerator of which indicates the distance in meters to one picket, the denominator to the other. These numbers should add up to 100, since the distance between two normal pickets is 100 m.

Breaking down the haul into anchor sections. We begin the placement of supports by transferring the insulating interfaces of the station to which the section is adjacent to the stage plan. The location of these supports on the stage plan must be linked to their location on the station plan. The linking is carried out according to the input signal, which is indicated both on the station plan and on the stage plan as follows: determine the distance between the signal and the support closest to it using the marks on the station plan. We add (or subtract) this distance to the signal picket mark and get the support picket mark. Then we set aside from this support the lengths of the next spans indicated on the station plan, and we obtain the picket marks of the insulating interface supports on the stage plan. We enter the picket marks of the supports in the “Support picket” column of the lower table. After this, we draw the insulating interface, since this is shown on the station plan, and arrange the zigzags of the contact wire.

Next, we outline the anchor sections of the contact network and the approximate location of their interfaces. After this, in the middle of the anchor sections, we outline the approximate location of the places for the middle anchors. In order to reduce the spans with average anchorage when laying out the supports in comparison with the maximum design length in this section of the stretch.

When planning the anchor sections of the suspension, it is necessary to proceed from the following considerations:

· the number of anchor sections on the stretch should be minimal;

· maximum length the anchor section of the contact wire on a straight line is assumed to be no more than 1600 m;

· in areas with curves, the length of the anchor section is reduced depending on the radius and location of the curve;

If the length of the curve is no more than half the length of the anchor section (800 m) and is located at one end or in the middle of the anchor section, then the length of such an anchor section can be taken equal to the average length permissible for a straight line and a curve of a given radius.

At the end of the section there should be a four-bay insulating junction separating the section and the next station; the supports of such a connection already belong to the station plan and are not taken into account on the stage plan. Sometimes in the initial data a part of the section is specified for design, limited by the next four-span insulating interface. The supports of such a connection refer to the stage plan.

We mark the approximate location of the supports for connecting anchor sections on the plan with vertical lines, the distance between which on a scale is approximately equal to three spans permissible for the corresponding section of the track. Then we mark with some conventional sign the location of the spans with medium anchorage and only after that we proceed to the placement of supports.

Arrangement of supports on the stretch. The placement of supports is carried out in spans, if possible equal to those permissible for the corresponding section of the path and terrain, obtained as a result of calculations of span lengths.

Outlining the installation locations for supports. You should immediately enter their chainage in the appropriate column, indicate the lengths of the spans between the supports, and use arrows to show the zigzags of the contact wires near the supports.

On straight sections of the track, zigzags (0.3 m) should be alternately directed at each of the supports, either in one or the other direction from the track axis, starting with the zigzag of the anchor support, transferred from the plan of the station contact network. On curved sections of the path, the contact wires are given zigzags in the direction from the center of the curve.

In places where there is a transition from a straight section of track to a curve, the zigzag wire at the support installed on the straight section of the track may be unrelated to the zigzag wire at the support installed on the curve. In this case, it is necessary to slightly reduce the length of one or two spans on a straight section of the track, and in some cases, a span partially located on a curve, so that a contact wire can be placed at one of these supports above the track axis (with zero zigzag), and at zigzag the contact wire adjacent to it in the desired direction.

Zigzags of the contact wire at adjacent supports located on straight and curved sections of the track can be considered linked if most of the span is located on a straight section of the track and the zigzags of the contact wire at the supports are made in different directions, or most of the span is located on a curved section of the track and zigzags are made one way.

The lengths of spans located partly on straight and partly on curved sections of the track can be taken equal to or slightly greater than the permissible span lengths for curved sections of the track. When laying out supports, the difference in the length of two adjacent spans of a semi-compensated suspension should not exceed 25% of the length of the larger span.

In areas where ice formations are often observed and self-oscillations of wires may occur, the breakdown of supports should be carried out in alternating spans, one of which is equal to the maximum permissible, and the other is 7-8 m less. At the same time, avoiding the frequency of alternating spans.

Spans with medium anchorages should be reduced: with a semi-compensated suspension - one span by 10%, and with a compensated suspension - two spans by 5% of the maximum design length in this place.

Selecting Supporting Devices

1. Selection of consoles.

Currently, non-insulated straight inclined consoles are used in AC sections.

The conditions for using uninsulated consoles in areas with ice thickness up to 20 mm and wind speeds up to 36 m/s in alternating current areas are given in the table

Table

Support type	Installation location			Type of console with dimensions of supports
				3,1-3,2		3,2-3,4	3,4-3,5
Intermediate	Straight			NR-1-5
	Curve			NS-1-6.5
	Inner side		R<1000 м
			R>1000 m
	Outer side		R<600 м	NR-1-5
			R>600 m
Transitional	Straight				NR-1-5
	Support A	Working
		Anchored			NS-1-5
	Support B	Working			NR-1-5
		Anchored			NS-1-5

Marking of consoles: NR-1-5 - non-insulated inclined console with stretched rod, bracket made of channels No. 5, bracket length 4730 mm.

NS-1-5 - non-insulated console with compressed rod, bracket made of channels No. 5, bracket length 5230 mm.

2. Selection of fasteners

The choice of clamps is made depending on the type of consoles and the location of their installation, and for transitional supports, taking into account the location of the working and anchored branches of the suspension relative to the support. In addition, take into account which of them the latch is intended for.

In the designations of typical clamps, the letters F - clamp, P - direct, O - reverse, A - contact wire of the anchored branch, G - flexible - are used. The markings contain numbers characterizing the lengths of the main rod.

The choice of clamps is summarized in the table

Table

Purpose of fasteners.			Types of clamps for support dimensions, m
			3,1-3,2	3,2-3,3	3,4-3,5
Intermediate supports	Straight	Zigzag to the support	FP-1
		Zigzag from the support	FO-II
	Outside of the curve	R=300 m	FG-2
		R=700 m	UFP-2
		R=1850 m	FP-II
	Inner side of the curve	R=300 m	UFO2-I
		R=700 m	UFO-I
		R=1850 m	FOII-(3.5)
Transition supports	Straight	Working	FPI-I
	Support A
		Anchored	FAI-III
	Support B	Working	FOI-III
		Anchored	FAI-IV

3. Selection of rigid crossbars.

When choosing rigid crossbars, first of all, determine the required length of the rigid crossbars.

L"=G 1 +G 2 +∑m+d op +2*0.15, m

Where: G 1, G 2 - dimensions of cross member supports, m

∑m is the total width of the tracks overlapped by the crossbar, m

d op =0.44 m – diameter of the support in the area of the rail heads

2*0.15 m – construction permit for the installation of cross member supports.

I tabulate the selection of rigid cross members

Table

4. Selection of supports

The most important characteristic of supports is their load-bearing capacity - the permissible bending moment M 0 at the level of the conventional foundation edge. Based on the load-bearing capacity, the types of supports are selected for use in specific installation conditions.

I tabulate the choice of supports

Table

Installation location	Support type	Rack brand
Straight	Intermediate	SO-136.6-1
	Transitional	SO-136.6-2
	Anchor	SO-136.6-3
Under a rigid crossbar (from 3-5 ways)	Intermediate	SO-136.6-2
Under a rigid crossbar (from 5-7 ways)	Intermediate	SO-136.6-3
Under a rigid crossbar (from 5-7 ways)	Anchor	SO-136.7-4
Curve	R<800 м	SO-136.6-3

Mechanical calculation of the anchor section of a semi-compensated suspension

For the calculation, we select one of the anchor sections of the main track of the station. The main purpose of mechanical calculation of chain suspension is to compile installation curves and tables. We perform the calculation in the following sequence:

1. Determine the calculated equivalent span using the formula:

where l i is the length of the i-th span, m;

L a – length of the anchor section, m;

n – number of spans.

Equivalent span for the first anchor section of the haul:

2. We establish the initial design mode at which the greatest tension in the supporting cable is possible. To do this, we determine the value of the critical span.

(17)

where Z max is the maximum reduced suspension tension, N;

W g and W t min are the reduced linear loads on the suspension, respectively, in case of ice with wind and at minimum temperature, N/m;

The temperature coefficient of linear expansion of the support cable material is 1/ 0 C.

The given values of Z x and W x for mode “X” are calculated using the formulas:

, N;

, N/m;

in the absence of horizontal loads q x = g x the expression will take the form:

, N/m;

in the complete absence of additional loads g x = g 0 and then the reduced load will be determined by the formula:

N/m; (18)

Here g x, q x are, respectively, the vertical and resulting loads on the supporting cable in the “X” mode, N/m;

K – tension of the contact wire(s), N;

T 0 – tension of the supporting cable in the weightless position of the contact wire, N;

j x – design coefficient of the chain suspension, determined by the formula:

The value “c” in the expression means the distance from the axis of the support to the first simple string (for a suspension with a spring cable, usually 8 - 10 m).

In a semi-compensated chain suspension, the contact wire has the ability to move when its length changes within the anchor section due to the presence of compensation. The supporting cable can also be considered as a loosely fixed wire, since turning the garland of insulators and using rotary consoles give it a similar opportunity.

For freely suspended wires, the initial design mode is determined by comparing the equivalent L e< L кр, то максимальное натяжение несущего троса T max ,будет при минимальной температуре, а если L э >L cr, then tension T max will occur during ice conditions with wind. The correctness of the choice of the initial mode is checked by comparing the resulting load during ice conditions q gn with the critical load q cr

The tension of the supporting cable in the weightless position of the contact wire is determined provided that j x = 0 (for spring suspensions), according to the formula:

(19)

Here, values with the index “1” refer to the mode of maximum tension of the supporting cable, and with the index “0” – to the mode of the weightless position of the contact wire. The index “n” refers to the material of the support cable, for example E n is the elastic modulus of the material of the support cable.

5. The tension of the unloaded support cable is determined by a similar expression:

(20)

Here g n is the load from the own weight of the supporting cable, N/m.

The value of A 0 is equal to the value of A 1, so there is no need to calculate A 0. By specifying different values of T px, temperatures t x are determined. Based on the calculation results, we will construct installation curves

Sag of the unloaded load-bearing cable at temperatures tx in real spans Li of the anchor section:

Rice. 3 Sag arrows of the unloaded load-bearing cable in real spans

7. The sag of the supporting cable F xi in the span l i is calculated from the expression:

; (22)

in the absence of additional loads (ice, wind) q x = g x = g, therefore the reduced load in the case under consideration:

; ;

Rice. 4 Arrows for sagging the loaded support cable

Calculations of the tension of the supporting cable under modes with additional loads, where values with the index x refer to the desired mode (ice with wind or wind of maximum intensity). The results obtained are plotted on a graph.

8. The sag of the contact wire and its vertical movement at the supports for real spans is determined accordingly by the formulas:

, (23)

Where ;

Here b 0i is the distance from the supporting cable to the spring cable against the support in the weightless position of the contact wire for the actual span, m;

H 0 is the tension of the spring cable, usually taken H 0 = 0.1T 0 .

(24)

Rice. 6 Sag of the contact wire in real spans under additional loads

Choosing a method for catenary passage in artificial structures

At the station:

The passage of a catenary under artificial structures, the width of which is no more than the interstring distance (2-12m), incl. under pedestrian bridges, can be done in one of three ways:

An artificial structure is used as a support;

The contact suspension is passed without fastening to an artificial structure;

An insulated insert is included in the supporting cable, which is attached to an artificial structure.

To select one of the methods, the following condition must be met:

For the first case:

where is the distance from the level of the rail heads to the lower edge of the artificial structure;

Minimum permissible height of contact wires above the level of rail heads;

The greatest sag of the contact wires with the sag of the supporting cable;

Minimum distance between the support cable and the contact wire in the middle of the span;

Maximum sag of the supporting cable;

Length of insulator garland:

Minimum support cable sag;

Part of the sag of the supporting cable at a minimum temperature at a distance from the closest approach to the artificial structure to the middle of the span;

Lifting the supporting cable under the influence of a pantograph at a minimum temperature;

Minimum permissible distance between live and grounded parts;

Permissible distance from the contact wire to the bumper.

Based on the results of this calculation, we come to the conclusion that in order to pass the catenary under a pedestrian bridge with a height of 8.3 meters, in our case it is necessary to use the third method: an insulated insert is cut into the supporting cable, which is attached to the bridge.

On the stretch:

The catenary suspension on bridges with a ride at the bottom and low wind connections is passed with fastening of the supporting cable to special structures installed above the wind connections. In this case, the contact wire is passed with fastening under the wind ties with a reduced span length of up to 25 m. The height of the structure is selected from the expressions:

For semi-compensated suspension:

Bibliography

1. Marquardt K. G., Vlasov I. I. Contact network. – M.: Transport, 1997.- 271 p.

2. Freifeld A.V. Design of a contact network. - M.: Transport, 1984, -397 p.

3. Handbook on electrical power supply for railways. /Edited by K.G. Marquardt - M.: Transport, 1981. - T. 2-392p.

4. Standards for the design of overhead contact networks (VSN 141 - 90). – M.: Ministry of Transport, 1992. – 118 p.

5. Contact network. Assignment for a course project with methodological instructions-M-1991-48s.

EXPLANATORY NOTE.

The guidelines are intended for full-time and part-time students of the Saratov Technical School of Railway Transport - a branch of SamGUPS in the specialty 02/13/07 Electrical supply (by industry) ( railway transport). The guidelines are compiled in accordance with work program professional module PM 01. Maintenance of equipment of electrical substations and networks.

As a result of execution practical work according to MDK 01.05 “Installation and maintenance of contact networks”, the teacher must:

master professional competencies:

PC 1.4. Maintenance of switchgear equipment of electrical installations;

PC 1.5. Operation of overhead and cable power lines;

PC 1.6. Application of instructions and regulatory rules in the preparation of reports and development of technological documents;

have general competencies:

OK 1. Understand the essence and social significance of your future profession, show sustained interest in it;

OK 2. Organize your own activities, choose standard methods and methods of performing professional tasks, evaluate their effectiveness and quality;

OK 4. Search and use information necessary for the effective performance of professional tasks, professional and personal development;

OK 5. Use information and communication technologies in professional activities;

OK 9. To navigate the conditions of frequent changes in technology in professional activities;

have practical experience:

Software 1. compilation electrical diagrams devices of electrical substations and networks;

Software 4. maintenance of equipment of switchgears of electrical installations;

Software 5. operation of overhead and cable power lines;

be able to:

U 5 monitor the condition of overhead and cable lines, organize and carry out work on their maintenance;

9 use regulatory technical documentation and instructions;

know:

Conditional graphic symbols elements of electrical circuits;

Logic for constructing circuits, standard circuit solutions, circuit diagrams operated electrical installations.

Types and technologies of work on maintenance of switchgear equipment;

Designing a station contact network is a complex process and requires a systematic approach to the implementation of the project using the achievements of modern technology and best practices, as well as the use of computer technology.

The guidelines address the issues of determining distributed loads on the supporting cable of an overhead catenary, determining the length of the equivalent and critical span, determining the tension values of the supporting cable depending on temperature, and constructing installation curves.

According to the given station layout, the following is required:

1. Calculation of distributed loads on the overhead catenary cable for main and side tracks.

4. Determination of the sag value of the contact wire and support cable for the main track, with the construction of curves. Calculation of the average string length.

5. Organization of safe work.

Individual assignments for practical work are given immediately before completion, in class. The time to complete each practical work is 2 academic hours, the time to defend the work done is 15 minutes included in the total time.

General guidance and control over the progress of practical work is carried out by the teacher of the interdisciplinary course.

PRACTICAL LESSON No. 1

SELECTION OF PARTS AND MATERIALS FOR CONTACT NETWORK UNITS

Purpose of the lesson: learn how to practically select parts for a given chain suspension.

Initial data: type and assembly of the catenary chain (set by the teacher)

Table 1.1

Table 1.2

When choosing a support unit and determining the method of anchoring the wires of the catenary chain, it is necessary to take into account the speeds of trains along a given section and the fact that the higher the speed of trains, the greater the elasticity of the catenary chain.

Contact network fittings are a set of parts intended for fastening structures, fixing wires and cables, and assembling various components of a contact network. It must have sufficient mechanical strength, good compatibility, high reliability and the same corrosion resistance, and for high-speed current collection, it must also have minimal weight.

All parts of contact networks can be divided into two groups: mechanical and conductive.

The first group includes parts designed only for mechanical loads: wedge and collet clamps for the supporting cable, saddles, fork thimbles, split and continuous lugs, etc.

The second group includes parts designed for mechanical and electrical loads: collet clamps for joining the supporting cable, oval connectors, butt clamps for contact wire clamps, string, string and transition clamps. According to the material of manufacture, fittings are divided into: cast iron, steel, non-ferrous metals and their alloys (copper, bronze, aluminum).

Products made of cast iron have a protective anti-corrosion coating - hot-dip galvanizing, and products made of steel - electrolytic galvanizing followed by chrome plating.

Fig. 1.1 Anchoring of a compensated catenary suspension of alternating (a) and direct (b) current.

1- Anchor guy; 2- anchor bracket; 3,4,19 - steel compensator cable with a diameter of 11 mm, length 10,11, and 13 m, respectively; 5- compensator block; 6- rocker arm; 7- rod “eye-double eye” 150 mm long; 8- adjustment plate; 9- insulator with pestle; 10- insulator with earring; 11- electrical connector; 12- rocker arm with two rods; 13.22 - clamp, respectively, for 25-30 loads; 14- limiter for garlands of weights, single (a) and double (b); 15- reinforced concrete load; 16- load limiter cable; 17 load limiter bracket; 18- mounting holes; 20- pestle-eye rod, 1000 mm long; 21- rocker arm for attaching two contact wires; 23-bar for 15 loads; 24- limiter for a single garland of weights; H0 is the nominal height of the contact wire suspension above the level of the rail head; bM is the distance from the loads to the ground or foundation, m.

Rice. 1.2 Anchoring of a semi-compensated AC chain suspension with a two-block compensator (a) and DC with a three-block compensator (b).

1- anchor guy; 2- anchor bracket; 3- pestle-eye rod, 1000 mm long; 4- insulator with pestle; 5- insulator with earring; 6- steel compensator cable with a diameter of 11 mm; 7- compensator block; pestle-eye rod 1000 mm long; 9- bar for weights; 10- reinforced concrete load; 11- limiter for a single garland of weights; 12- load limiter cable; 13- load limiter bracket; 14- steel compensator cable with a diameter of 10 mm and a length of 10 m; 15- clamp for weights; 16- limiter for a double garland of weights; 17- rocker for anchoring two wires.

Fig. 1.3 Average anchorage of compensated (a-d) and semi-compensated (f) contact suspensions for a single contact wire (b), double contact wire (d), fastening the supporting cable and the average anchorage cable on an insulated console (c) and on a non-insulated console (d).

1- main support cable; 2- cable for the middle anchorage of the contact wire; 3- additional cable; 4-pin wire; 5- connecting clamp; 6- middle anchorage clamp; 7- isolated console; 8 - double saddle; 9- middle anchorage clamp for fastening to the supporting cable; 10- insulator.

Rice. 1.4 Fastening the support cable to a non-insulated console.

Rice. 1.5 Fastening the supporting cable to a rigid cross member: a - general view with a fixing cable; b- with a locking stand; and - triangular suspension with brackets.

1-support; 2- crossbar (crossbar); 3- triangular suspension; 4- fixing cable; 5- fixation stand; 6- latch; 7- rod with a diameter of 12 mm; 8- bracket; 9- earring with pestle; 10- hook bolt.

Execution order.

1. Select a support node for a given catenary and sketch it with all geometric parameters (Fig. 1.1, 1.2, 1.3,)

2. Select the material and cross-section of wires for simple and spring strings of the support unit.

3. Select using fig. 1.1, 1.2, 1.3, 1.4, 1.5, parts for a given unit, the name and characteristics of which must be entered in the table. 1.3.

Table 1.3

4. Apply a detail for joining the contact wire and connecting the support cable, which are also entered in the table. 1.3.

5. Describe the purpose and installation location of longitudinal and transverse connectors.

6. Describe the purpose of non-isolating interfaces. Draw a diagram of a non-insulating interface and indicate all the main dimensions.

7. Prepare a report. Draw conclusions.

Contact network devices

CS is a complex system consisting of many devices. Each of them performs its own individual function. According to the functionality, the requirements for individual elements of the CS also differ. General requirements refer to mandatory serviceability, compliance with quality and safety standards.

CS devices usually include: all supporting and supporting structures that are designed to ensure a reliable and stable position of the leading current elements of the CS, organized by the suspension method; parts for fastening and fixing the CS along the supports of the CS or overhead lines on individual overhead line supports; supporting and auxiliary cables of different designs and different purposes depending on the design requirements of the compressor station; the KS wires themselves, which represent the main wire (it is called the contact wire), as well as wires for other purposes - reinforcing, suction, power supply, auto-blocking power supply. devices, power supply, etc.

In the process of work, almost all elements of the CS are influenced by various factors. The largest share of this influence comes from natural environmental factors. Throughout its entire working life, the CS is in the open air, therefore it is constantly exposed to the influence of precipitation, wind, sudden changes in temperature, ice conditions, etc. All these conditions negatively affect the state of the CS and its operation, causing a change in the lengths of the wires, the occurrence of sparking phenomena, and electric current. arcs, the phenomenon of corrosion for supports and other metal elements. It is not possible to completely get rid of these phenomena, however, it is possible to improve the network’s resistance to the external environment using various technical and technological methods, as well as the use of resistant and reliable materials in construction.

The compressor station must provide maximum resistance to external environmental factors, and, moreover, ensure uninterrupted movement of EPS along a line with established standards for weight, speed, schedule and interval between trains passing one after another.

Particular attention should be paid to the stability and reliability of the CS also because, unlike other power supply lines, it does not provide for a reserve. That is, this means that if any of the elements of the CS fails, this will lead to a complete shutdown of the line. It will be possible to resume the movement of rolling stock only after the necessary repair work has been carried out and supply has been restored.

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

Contact network design

When designing a contact network (CN), 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 movement of the EPS and other current collection conditions; find the span lengths (mainly 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 coordination of zigzags of wires and taking into account the implementation of overhead switches 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 Г from the axis of the outer track 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 protected from the electrocorrosive effects of stray currents on their reinforcement. Increasing the service life of contact wires is achieved, as a rule, by using inserts on pantographs with high antifriction properties (carbon, including metal-containing, metal-ceramic, etc.), choosing a rational design of pantographs, as well as optimizing current collection modes.
To increase the reliability of the contact network, ice is melted, incl. without interruption of train traffic; wind-resistant contact pendants are used, etc. The efficiency of work on the contact network is facilitated by the use of telecontrol for remote switching of sectional disconnectors.

Wire anchoring

Anchoring of wires is the attachment of catenary wires 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 a given tension.

In the middle of the catenary anchor section, a middle anchorage is performed (Fig. 8.17), which prevents unwanted longitudinal movements towards one of the anchors and allows you to limit the area of damage to the catenary when one of its wires breaks. The middle anchorage cable is attached to the contact wire and the supporting cable with appropriate fittings.

Wire Strain Compensation

Compensation of wire tension (automatic regulation) 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-load compensator, consisting of a load and several blocks (pulley hoist), through which the load is connected to the anchored wire. The most widely used is the three-block compensator (Fig. 8.18), in which a fixed block is fixed to a support, and two movable ones are inserted into loops formed by a cable carrying a load and fixed at the other end in the stream of a 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 rated tension (a 1:4 gear ratio is provided), but the movement of the load is twice as large as that of a two-6-lobe compensator (with one moving block).

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

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

Contact wire clamp

Contact wire clamp – a device for fixing the position of the contact wire in a horizontal plane relative to the axis of the pantograph. On curved sections, where the levels of the rail heads are different and the axis of the pantograph does not coincide with the axis of the track, non-articulated and articulated clamps are used.
A non-articulated clamp has one rod that pulls the contact wire from the axis of the pantograph to the support (extended clamp) or from the support (compressed clamp) by a zigzag size. On electrified railways non-articulated clamps are used very rarely (in anchored branches of a catenary suspension, on some air switches), since the “hard point” formed with these clamps on the contact wire impairs current collection.

The articulated clamp consists of three elements: the main rod, the stand and an additional rod, at the end of which the contact wire fixing clamp is attached (Fig. 8.20). The weight of the main rod is not transferred to the contact wire, and it only takes part of the weight of the additional rod with a fixing clip. The rods are shaped to ensure reliable passage of the pantographs when they press 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 stand. On the outer side of curves of small radii, flexible clamps are mounted in the form of a conventional additional rod, which is attached to a bracket, rack or directly to a support through a cable and an insulator. On flexible and rigid crossbars with fixing cables, strip fasteners are usually used (similar to an additional rod), hingedly secured with clamps with an eye mounted on the fixing cable. On rigid crossbars, you can also attach clamps to special racks.

Anchor section

Anchoring section is a section of a catenary suspension, the boundaries of which are anchor supports. Dividing 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 area in the event of a break in the catenary wires, facilitates installation, technical. contact network maintenance and repair. The length of the anchor section is limited by permissible deviations from the nominal tension value of the catenary wires set by the compensators.
Deviations are caused by changes in the position of strings, clamps and consoles. For example, at speeds up to 160 km/h, the maximum length of the anchor section with bilateral 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 transition from one anchor section to the next, non-insulating and insulating connections are made.

Pairing anchor sections

Conjugation of anchor sections is a functional combination of two adjacent anchor sections of a catenary system, ensuring a satisfactory transition of EPS pantographs from one of them to another without disturbing the current collection mode due to the appropriate placement in the same (transition) spans of the contact network of the end of one anchor section and the beginning of the other. A distinction is made between non-insulating (without electrical sectioning of the contact network) and insulating (with sectioning).
Non-insulating connections are made in all cases where it is necessary to include compensators in the catenary wires. In this case, mechanical independence of the anchor sections is achieved. Such connections are installed in three (Fig. 8.21, a) and less often in two spans. On high-speed highways, connections are sometimes carried out in 4-5 spans due to higher requirements for the quality of current collection. Non-insulating interfaces have longitudinal electrical connectors, the cross-sectional area of which must be equivalent to the cross-sectional area of the overhead wires.

Insulating interfaces are used when it is necessary to section the contact network, when, in addition to the mechanical one, it is necessary to ensure the electrical independence of the mating sections. Such connections are arranged with neutral inserts (sections of the catenary where there is normally no voltage) and without them. In the latter case, three or four span connections are usually used, placing the contact wires of the mating sections in the middle span(s) 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 transition 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 coupling. However, when the pantograph is in the middle span, the electrical independence of the anchor sections is compromised. If such a violation is unacceptable, neutral inserts of different lengths are used. It is chosen in such a way that when several pantographs of one train are raised, the simultaneous blocking of both air gaps is excluded, which would lead to the short circuit of wires powered from different phases and under different voltages. To avoid burning out the contact wire of the EPS, coupling with the neutral insert takes place on the run-out, for which purpose a signal sign “Turn off the current” is installed 50 m before the start of the insertion, and after the end of the insertion for electric locomotive traction after 50 m and for multiple unit traction after 200 m - the sign “ Turn on the current" (Fig. 8.21c). In areas with high-speed traffic, automatic means of switching off the current to the EPS are required. To make it possible to derail the train when it is forced to stop under the neutral insert, sectional disconnectors are provided to temporarily supply voltage to the neutral insert from the direction of train movement.

Catenary sectioning

Sectioning of a contact network is the division of a contact network into separate sections (sections), electrically separated by insulating connections of anchor sections or sectional insulators. The insulation may be broken during the passage of the EPS pantograph along the section interface; if such a short circuit is unacceptable (when adjacent sections are powered from different phases or belong to different traction power supply systems), neutral inserts are placed between the sections. Under operating conditions, the electrical connection of individual sections is carried out, including sectional disconnectors installed in appropriate places. Sectioning is also necessary for reliable operation of power supply devices in general, prompt maintenance and repair of the contact network with voltage cutoff. The sectioning scheme provides for such a mutual arrangement of sections in which the disconnection of one of them has the least impact on the organization of train traffic.
Sectioning of the contact network can be longitudinal or transverse. With longitudinal sectioning, the contact network of each main track is divided along the electrified line at all traction substations and sectioning posts. The contact network of stages, substations, sidings and passing points is divided into separate longitudinal sections. At large stations with several electrified parks or groups of tracks, the contact network of each park or groups of tracks forms independent longitudinal sections. At very large stations, the contact network of one or both necks is sometimes separated into separate sections. The contact network is also sectioned in long tunnels and on some bridges with traffic below. With transverse sectioning, the contact network of each of the main paths is divided along the entire length of the electrified line. At stations with significant track development, additional transverse sectioning is used. The number of transverse sections is determined by the number and purpose of individual tracks, and in some cases, by the starting modes of the EPS, when it is necessary to use the cross-sectional area of the overhead catenaries of adjacent tracks.
Sectioning with mandatory grounding of the disconnected section of the contact network is provided for tracks on which there may be people on the roofs of cars or locomotives, or tracks near which lifting and transport mechanisms operate (loading and unloading, equipment tracks, etc.). To ensure greater safety for those working in these places, the corresponding sections of the contact network are connected to other sections by sectional disconnectors with grounding blades; these knives ground the disconnected sections when the disconnectors are turned off.

In Fig. 8.22 shows an example of a power supply and sectioning circuit for a station located on a double-track section of a line electrified with alternating current. The diagram shows seven sections - four on the hauls and three at the station (one of them with mandatory grounding when it is turned off). The contact network of the tracks of the left section and the station receives power from one phase of the power system, and the tracks of the right section - from the other. Accordingly, sectioning was carried out 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 manually operated sectional disconnector is sufficient.

To section the contact network of the main and lateral networks at 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 not sufficient to accommodate insulating connections.
The connection and disconnection of various sections of the contact network, as well as connection to the supply lines, is carried out using sectional disconnectors. On AC lines, as a rule, horizontal-rotating type disconnectors are used, on DC lines - vertical-cutting type. The disconnector is controlled remotely from consoles installed in the duty station of the contact network area, in the premises of station duty officers 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, V, D; 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 paths for equipping and inspecting roof equipment of EPS, on the paths for loading and unloading cars, etc.), disconnectors with one grounding blade are installed.

Frog

Air switch - formed by the intersection of two overhead contacts above the switch; is designed to ensure 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 pantograph approaches the air needle, 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 intersection of contact wires above a single turnout is carried out with each wire displaced to the center from the track axes by 360-400 mm and located where the distance between the inner edges of the heads of the crosspiece connecting rails is 730-800 mm. At cross switches and at the so-called. At blind intersections, the wires cross over the center of the switch or intersection. Air gunners are usually fixed. To do this, clamps are installed on the supports to hold the contact wires in a given position. On station tracks (except for the main ones), switches can be made non-fixed if the wires above the switch are located in the position specified by adjusting the zigzags at the intermediate supports. The catenary strings located near the arrows must be double. Electrical contact between the catenary pendants forming the arrow is provided by an electrical connector installed at a distance of 2-2.5 m from the intersection on the arrow side. To increase reliability, switch designs with additional cross connections between the wires of both catenary pendants and sliding supporting double strings are used.

Catenary supports

Contact network supports are structures for fastening the supporting and fixing devices of the contact network, taking the load from its wires and other elements. Depending on the type of supporting device, supports are divided into cantilever (single-track and double-track); racks of rigid crossbars (single or paired); flexible crossbar supports; feeder (with brackets only for supply and suction wires). Supports that do not have supporting devices, but have fixing devices, are called fixing ones. Cantilever supports are divided into intermediate ones - for attaching one catenary suspension; transitional, installed at the junction of anchor sections, - for fastening two contact wires; anchor, absorbing the force from anchoring the wires. As a rule, supports perform several functions simultaneously. For example, the support of a flexible crossbar can be anchored, and consoles can be suspended from the racks of a rigid crossbar. Brackets for reinforcing and other wires can be attached to the support posts.
The supports are made of reinforced concrete, metal (steel) and wood. On domestic trains d. they mainly use 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, due to their load-bearing capacity or size, it is impossible to use reinforced concrete ones (for example, in flexible crossbars), as well as on lines with high-speed traffic, where increased requirements are placed on the reliability of supporting structures. Wooden supports are used only as temporary supports.

For direct current sections, reinforced concrete supports are made with additional rod reinforcement located in the foundation part of the supports and designed to reduce damage to the support reinforcement by electrocorrosion caused by stray currents. Depending on the installation method, reinforced concrete supports and racks of rigid crossbars can be separated or non-separated, installed directly into the ground. The required stability of undivided supports in the ground is ensured by the upper beam or base plate. In most cases, undivided supports are used; separate ones are used when the stability of non-separated ones is insufficient, as well as in the presence of groundwater, which makes it difficult to install non-separated supports. In reinforced concrete anchor supports, guys are used, which are installed along the track at an angle of 45° and attached to the reinforced concrete anchors. Reinforced concrete foundations in the above-ground part have a glass 1.2 m deep, into which supports are installed and then the cavity of the glass is sealed with cement mortar. To deepen foundations and supports into the ground, the method of vibration immersion is mainly used.
The metal supports of flexible crossbars are usually made of a tetrahedral pyramidal shape, their standard length is 15 and 20 m. Longitudinal vertical posts made of angle bars are connected by a triangular lattice, also made from angle iron. 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 cross beam 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 secure supports in rocky soils, heaving soils in areas of permafrost and deep seasonal freezing, in weak and swampy soils, etc., foundations of special structures are used.

Console

Console is a supporting device mounted on a support, consisting of a bracket and a rod. Depending on the number of overlapped paths, the console can be single-, double-, or less often multi-path. To eliminate the mechanical connection between catenaries of different tracks and increase reliability, single-track consoles are more often used. Non-insulated or grounded consoles are used, in which the insulators are located between the supporting cable and the bracket, as well as in the clamp rod, and insulated consoles with insulators located in the brackets and rods. Non-insulated consoles (Fig. 8.25) can be curved, inclined or horizontal in shape. For supports installed with increased dimensions, consoles with struts are used. At the junctions of anchor sections when installing 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 insulated consoles (Fig. 8.26), it is possible to carry out work on the supporting cable near them without disconnecting the voltage. The absence of insulators on non-insulated consoles ensures greater stability of the position of the supporting cable under various mechanical influences, which has a beneficial effect on the current collection process. The brackets and rods of the consoles are mounted on supports using heels that allow them to rotate along the track axis by 90° in both directions relative to the normal position.

Flexible crossbar

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

The fixing cables take up horizontal loads (the upper one is from the supporting cables of the chain hangers and other wires, the lower one is from the contact wires). Electrical insulation of cables from supports allows servicing the contact network without disconnecting the voltage. To regulate their length, all cables are secured to supports using threaded steel rods; in some countries, special dampers are used for this purpose, mainly for fastening contact suspension at stations.

Current collection

Current collection is the process of transferring electrical energy from a contact wire or contact rail to the electrical equipment of a moving or stationary EPS through a current collector, providing sliding (on highway, industrial and most urban electric transport) or rolling (on some types of EPS of urban electric transport) electrical contact. Violation of contact during current collection leads to the occurrence of non-contact electric arc erosion, which results in intense wear of the contact wire and contact inserts of the current collector. When contact points are overloaded with current during movement, contact electrical explosion erosion (sparking) and increased wear of the contacting elements occur. Long-term overload of the contact with operating current or short-circuit current when the EPS is parked can lead to burnout of the contact wire. In all these cases, it is necessary to limit the lower limit of contact pressure for the given operating conditions. Excessive contact pressure, incl. as a result of the aerodynamic impact on the pantograph, an increase in the dynamic component and the resulting increase in the vertical deflection of the wire, especially at clamps, on air switches, 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 ensured by coordinated requirements for contact network devices and current collectors, which guarantees high reliability of their operation at minimal reduced costs.
The quality of current collection can be determined by various indicators (the number and duration of violations of mechanical contact on the calculated section of the track, the degree of stability of contact pressure close to the optimal value, the rate of wear of contact elements, etc.), which largely depend on the design of the interacting systems - the contact network and pantographs, their static, dynamic, aerodynamic, damping and other characteristics. Despite the fact that the current collection process depends on a large number of random factors, research results and operating experience make it possible to identify the fundamental principles for creating current collection systems with the required properties.

Rigid cross member

Rigid crossbar - used for hanging overhead wires located above several (2-8) tracks. The rigid crossbar 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 connected either hingedly or rigidly using struts, allowing it to be unloaded in the middle of the span and reducing steel consumption. When placing lighting fixtures on the crossbar, a flooring with railings is made on it; provide a ladder for climbing to the supports for service personnel. Install rigid crossbars ch. arr. at stations and separate points.

Insulators

Insulators are devices for insulating live contact wires. Insulators are distinguished according to the direction of application of loads and the installation location - suspended, tensioned, retaining and cantilever; by design - disc and rod; by material - glass, porcelain and polymer; insulators also include insulating elements
Suspended insulators - porcelain and glass dish insulators - 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 supporting 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 securing the pipe. On AC lines, rod insulators are usually used, and on DC lines, disc insulators are also used. In the latter case, another disc-shaped insulator with an earring is included in the main rod of the articulated clamp. Cantilever porcelain rod insulators (Fig. 8.31) are installed in the 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 direct current lines, polymer insulating elements are used in the form of rectangular bars made of press material, and on alternating current lines - in the form of cylindrical fiberglass rods, on which electrical protective covers made of fluoroplastic pipes are put on. Polymer rod insulators with fiberglass cores and ribs made of organosilicon elastomer 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.

Catenary

The catenary is one of the main parts of the contact network; it is a system of wires, the relative arrangement of which, the method of mechanical connection, material and cross-section provide the necessary quality of current collection. The design of a catenary (CP) is determined by economic feasibility, operating conditions (maximum speed of movement of the EPS, maximum current drawn by pantographs), and climatic conditions. The need to ensure reliable current collection at increasing speeds and power of the EPS determined the trends in changes in suspension designs: first simple, then single with simple strings and more complex - spring single, double and special, in which, to ensure the required effect, Ch. arr. to level the vertical elasticity (or rigidity) of the suspension in the span, space-stayed systems with an additional cable or others are used.
At speeds of up to 50 km/h, 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. 8.10a) or transverse cables.

The quality of 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 wire’s own weight (in case of icy conditions along with ice) and wind load, as well as on the span length and tension of the wire. The quality of current collection is greatly influenced by angle a (the smaller it is, the worse quality current collection), contact pressure changes significantly, shock loads appear in the support zone, increased wear of the contact wire and current collector inserts occurs. Current collection in the support zone can be somewhat improved by hanging the wire at two points (Fig. 8.10.6), which under certain conditions ensures reliable current collection at speeds of up to 80 km/h. It is possible to significantly improve 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 hangers are used (Fig. 8.11), in which the contact wire is suspended from the supporting cable using strings. A suspension consisting of a support cable and a contact wire is called single; if there is an auxiliary wire between the support cable and the contact wire - double. In a chain suspension, the supporting cable and the auxiliary wire are involved in the transmission of traction current, so they are connected to the contact wire by 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 upward. The quality of current collection depends on the nature of the change in elasticity over the span: the more stable it is, the better the current collection. In simple and conventional chain hangers, the elasticity at mid-span is higher than that of the supports. Equalization of elasticity 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 rational arrangement of ordinary strings in the middle part of the span. Double suspensions have more constant elasticity, but they are more expensive and more complex. To obtain a high rate of uniform distribution of elasticity in the span, use various ways its increase in the area of the support unit (installation of spring shock absorbers and elastic rods, torsion effect from twisting the cable, 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 catenary is an oscillating system, therefore, when interacting with pantographs, it can be in a state of resonance caused by the coincidence or multiple frequencies of its own oscillations and forced oscillations, determined by the speed of the pantograph along a span with a given length. If resonance phenomena occur, a noticeable deterioration in current collection may occur. The limit for current collection is the speed of propagation of mechanical waves along the suspension. If this speed is exceeded, the pantograph has to interact as if with a rigid, non-deformable system. Depending on the standardized specific tension of the suspension wires, this speed can be 320-340 km/h.
Simple and chain hangers consist of separate anchor sections. The suspension fastenings at the ends of the anchor sections can be rigid or compensated. On the main railways Mostly compensated and semi-compensated suspensions are used. In semi-compensated suspensions, compensators are present only in the contact wire, in compensated ones - also in the supporting cable. Moreover, 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 supporting cable, and therefore the vertical position of the contact wires, remains 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 supporting 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, insulating distances, especially in the area of artificial structures, etc.; in addition, a minimum inclination of the strings must be ensured at extreme values of ambient temperature, when noticeable longitudinal movements of the contact wire relative to the supporting cable may occur. For compensated suspensions, this is possible if the support cable and contact wire are made of different materials.
To increase the service life of the contact inserts of pantographs, the contact wire is placed in a zigzag plan. Various options for hanging the support cable are possible: in the same vertical planes as the contact wire (vertical suspension), along the axis of the track (semi-oblique suspension), with zigzags opposite to the zigzags of the contact wire (oblique suspension). The vertical suspension has less wind resistance, the oblique suspension has 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 supporting cable, are located at supports with opposite zigzags. In the middle parts of the spans, the wires are pulled together by rigid strips. In some suspensions, lateral stability is ensured by the use of two supporting cables, forming a kind of cable-stayed system in the horizontal plane.
Abroad, single chain suspensions are mainly used, including on high-speed sections - with spring wires, simple spaced support strings, as well as with supporting cables and contact wires with increased tension.

Contact wire

The contact wire is the most critical element of the contact suspension, directly making contact with the EPS pantographs during the current collection process. Typically, one or two contact wires are used. Two wires are usually used when collecting currents of more than 1000 A. On domestic railways. d. 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 underwent some changes; in the beginning. 20th century the cross-section profile took the form with two longitudinal grooves in the upper part - the head, which serve to secure the contact network fittings to the wire. In domestic practice, the dimensions of the head (Fig. 8.12) are the same for different cross-sectional areas; in other countries, head sizes depend on 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 - shaped copper, cross-sectional area 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. Bronze copper-cadmium wires have the best wear resistance (2-2.5 times higher than copper wire), but they are more expensive than copper wires, and their electrical resistance is higher. The feasibility of using a particular 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 highways. Of particular interest is the 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, contact wires wear out when collecting current. There are electrical and mechanical components of wear. To prevent wire breakage due to increased tensile stresses, the maximum wear value is normalized (for example, for a wire with a cross-sectional area of 100 mm, the permissible wear is 35 mm2); As wear on the wire increases, its tension is periodically reduced.
During operation, rupture of the contact wire can occur as a result of the thermal effect of electric current (arc) in the area of interaction with another device, i.e., as a result of burnout of the wire. Most often, contact wire burnouts occur in the following cases: above the current collectors of a stationary 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 pantograph; presence of ice; closing the pantograph skid of the different-nopothecial 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, which prevents the pantograph from rising under load and forcibly turns it off when lowered; equipment for insulating connections of anchor sections protective devices, helping to extinguish the arc in the area of its possible occurrence; timely measures to prevent ice deposits on wires, etc.

Support cable

Support cable - a chain suspension wire attached to the supporting devices of the contact network. A contact wire is suspended from the supporting cable using strings - directly or through an auxiliary cable.
On domestic trains On the main tracks of lines electrified with direct current, copper wire with a cross-sectional area of 120 mm2 is mainly used as a supporting cable, and on the side tracks of stations, steel-copper wire (70 and 95 mm2) is used. Abroad, bronze and steel cables with a cross-section from 50 to 210 mm2 are also used on AC lines. The cable tension in a semi-compensated catenary varies depending on the ambient temperature in the range from 9 to 20 kN, in a compensated suspension depending on the type of wire - in the range of 10-30 kN.

String

A string is an element of a catenary chain, with the help of which one of its wires (usually a contact wire) is suspended from another - the supporting cable.
By design, they are distinguished: link strings, composed of two or more hingedly connected links of rigid wire; flexible strings made of flexible wire or nylon rope; hard - in the form of spacers between the wires, used much less frequently; loop - made of wire or 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 trains The most widely used are 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 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 for link and other connections, do not have this drawback. non-conducting strings. Sometimes non-conductive catenary strings made of nylon rope are used, the fastening of which requires transverse electrical connectors.
Sliding strings, capable of moving along one of the wires, are used in semi-compensated catenary pendants with a low structural height, when installing sectional insulators, in places where the supporting cable is anchored on artificial structures with limited vertical dimensions and in other special conditions.
Rigid strings are usually installed only on the overhead switches of the contact network, where they act as a limiter for the rise of the contact wire of one suspension relative to the wire of the other.

Reinforcing wire

Reinforcing wire - a wire electrically connected to the catenary, serving to reduce the overall electrical resistance 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 supporting cable. The reinforcing wire is used in areas of direct and alternating current. Reducing the inductive reactance of an AC contact network depends not only on the characteristics of the wire itself, but also on its placement relative to the overhead wires.
The use of reinforcing wire is provided for at the design stage; Typically, one or more A-185 type stranded wires are used.

Electrical connector

Electrical connector - a piece of wire with conductive fittings intended for electrical connection contact wires. There are transverse, longitudinal and bypass connectors. They are made from bare wires so that they do not interfere with the longitudinal movements of the catenary wires.
Transverse connectors are installed for parallel connection of all overhead wires of the same track (including reinforcing ones) and at catenary stations for several parallel tracks included in one section. Transverse connectors are mounted along the track at distances depending on the type of current and the proportion of the cross-section of the contact wires in the general cross-section of the contact wires, as well as on the operating modes of the EPS on specific traction arms. In addition, at stations, connectors are placed in the places where the EPS starts and accelerates.
Longitudinal connectors are installed on the air switches between all the wires of the catenary pendants forming this switch, in the places where the anchor sections are coupled - on both sides for non-insulating joints and on one side for insulating joints and in other places.
Bypass connectors are used in cases where it is necessary to make up for the interrupted or reduced cross-section of the catenary suspension due to the presence of intermediate anchoring of reinforcing wires or when insulators are included in the supporting cable for passage through an artificial structure.

Catenary fittings

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

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