Power poles. Poles of overhead power lines. Their device and main types. Benefits of wooden poles

A complete list of overhead line supports presented on our website can be found on the tabs below. First select the material from which the support is made, and then the voltage rating of the line. After that, go to the page with a list of overhead lines. Please note that the list of supports is constantly updated.

Power transmission towers are perhaps one of the most complex elements power lines. When designing and building these structures, it is necessary to take into account both climatic and soil characteristics of the area. Currently, manufacturers of supports are striving to reduce the cost of production and increase the strength characteristics of products.

In view of this, they are developing various designs, allowing to reduce the load on the foundation and ensure stable operation in various modes work.

On our site you can get acquainted with both old and new developments of Russian engineers.

Classification by purpose

Each brand of supports is designed to perform its specific function. That is why designs are divided into main types depending on the purpose:

1. intermediate supports- the most common type of supports, designed for vertical loads from the weight of the wires, installed only on straight sections of the line;
2. anchor supports- also installed on straight sections of the route, however, the wires are anchored to them. Thus, the supports are designed for longitudinal loads from the tension of the wires;
3. corner supports- installed at the corners of the track. The fastening of wires on them is also in most cases anchored, however, there are exceptions in the form of intermediate corner supports;
4. end supports- are usually mounted in front of substations. Loads act on them mainly from one side of the line;
5. transpositional- designed to perform the transposition of overhead lines;
6. branch- are installed in places of branches of the line to an adjacent direction;
7. transitional- to ensure clearance over an engineering structure or a natural barrier.

Classification by materials of manufacture

Structures are installed in various climatic, geoseismic conditions. At the same time, it should be noted that many types of supports are designed for operation in urban areas. Thus, in each case, it is required to use suitable material for making racks.

wooden supports

Wooden power line poles are widely used in the conditions countryside, however, do not forget that the corresponding wooden structures are also used on lines up to 220kV.

Wooden structures are most often used on low voltage lines, while they have a number of advantages:

1. relative durability (up to 50 years with appropriate impregnation);
2. light weight;
3. ease of construction and transportation;
4. low cost.

Reinforced concrete supports

Reinforced concrete supports are installed on lines with a voltage of less than 500 kV. Basically, these are intermediate supports that do not take on the load from the tension of wires and cables. In case of use reinforced concrete racks as anchor supports, they are strengthened with slopes or braces.

Reinforced concrete supports are made from prestressed reinforced concrete and have a number of advantages:

1. not complicated design features;
2. do not require complex additional assembly;
3. not subject to decay, like wooden supports;
4. in some cases, installation directly into the ground is possible;
5. relatively simple line construction.

Steel supports

Steel supports on 0.4-10 kV lines are extremely rare. Their prerogative is the lines of medium voltage and above. Metal poles are mainly used as anchor poles, however, with a network voltage of more than 110 kV, intermediate steel poles are also used.

Structures can be made both from a profile and corners, and by rolling, since metal supports based on pipes are often used in lighting. Among the advantages of supports of this type, one can note their wear resistance and durability, as well as the possibility of manufacturing very high construction to ensure safe passage through engineering structures and natural barriers.

Typical designs are presented for each type of support. As a result, you will be confident in your choice, as you will familiarize yourself with all the necessary documentation.

Overhead power line towers

Overhead lines with a voltage of 0.4-35 kV

Overhead lines with voltage up to 1 kV are called lines low voltage(LV), 1 kV and more - high voltage(VN).

Low-voltage lines are the simplest structures in the form of single poles buried directly into the ground, with metal pins and insulators attached to them, to which wires are attached.

As supports, wooden, reinforced concrete and, less commonly, metal supports are used. The latter, as a rule, are used at critical intersections (electrified railways, highways, etc.). Wooden supports can be composite on wooden or reinforced concrete attachments or from solid logs of the appropriate length and diameter. Three wires are suspended on 6-35 kV lines, and on 0.4 kV lines, supports allow joint suspension of up to eight wires of brand A (Ap) with a cross section of 16-50 mm2.

HV lines 3-10 kV do not fundamentally differ from LV lines, however, due to the large distances between the phases and between the wires and the ground, the dimensions of the elements - poles, pins, insulators - are increased.

Reinforced concrete pylons for power transmission lines are designed and operated in areas with design temperature air down to -55°С. The main element of such supports are centrifuged reinforced concrete racks. In addition to centrifuged racks, the structure of the reinforced concrete support of power transmission lines can include anchor plates, crossbars, anchors for guy wires, a lower concrete cover (thrust bearing) and metal structures in the form of traverses, extensions, cable racks, head restraints, clamps, braces, internal connections, attachment points. Fastening of metal structures to the support post is carried out using clamps or through bolts. Reinforced concrete supports are fixed in the ground by installing them in a cylindrical pit, followed by filling the sinuses with a sand and gravel mixture. To ensure the necessary strength of embedding in soft soils, crossbars are fixed on the underground part of the overhead line supports with the help of half-clamps. The main disadvantage of reinforced concrete supports is low strength and weight characteristics, and as a result high costs during transportation due to the large dimensions and weight of the products. Dignity - high corrosion resistance to aggressive environments.

Classification reinforced concrete supports VL

By appointment

intermediate supports are installed on straight sections of the overhead line route, are intended only for supporting wires and cables and are not designed for loads directed along the power line. As a rule, the total number of intermediate supports is 80 - 90% of all power transmission line supports.

Anchor supports are used on straight sections of the overhead line route at places of transition through engineering structures or natural barriers to limit the anchor span, as well as at places where the number, grades and cross sections of power line wires change. Anchor support perceives the load from the difference in tension of wires and cables, directed along the power line. The design of anchor reinforced concrete supports of overhead lines is characterized by increased strength. This is ensured, among other things, by the use of reinforced concrete pillars of increased strength in the support.

Angle supports designed for operation in places where the direction of the overhead line route changes, they perceive the resulting load from the tension of wires and cables of adjacent intersupport spans. At small angles of rotation (15 - 30 °), where the loads are small, angular intermediate supports are used. At angles of rotation of more than 30 °, angle anchor supports are used, which have more solid construction and anchor wires.

end supports are a kind of anchor and are installed at the end and beginning of the power line, designed for the load from the one-sided tension of all wires and cables.

Special supports used for special tasks: transpositional- to change the order of the wires on the supports; transitional- to cross the power line through engineering structures or natural barriers; branch- for the device of branches from the main power line; antiwind- to enhance mechanical strength power line section; cross- when crossing overhead power lines in two directions.

By design

Portal reinforced concrete supports of overhead lines with braces

Portal free-standing supports with internal connections

Single, double, triple and multi-column free-standing poles

One-, two-, three- and multi-stay guyed poles

By number of chains

single chain

double chain

Multi-chain

VL supports are divided into anchor and intermediate. The supports of these two main groups differ in the way the wires are suspended. On the intermediate supports, the wires are suspended with the help of supporting garlands of insulators. Anchor-type supports are used to tension the wires, on these supports the wires are suspended using hanging garlands. The distance between the intermediate supports is called the intermediate span or simply the span, and the distance between the anchor supports is called the anchor span.

1. Anchor supports are designed for rigid fastening of wires at critical points of overhead lines: at the intersections of especially important engineering structures (for example, railways, 330-500 kV overhead lines, highways the width of the carriageway is more than 15 m, etc.), at the ends of the overhead line and at the ends of its straight sections. Anchor supports on straight sections of the overhead line route when wires are suspended on both sides of the support with the same tensions in normal operating modes of the overhead line perform the same functions as the intermediate supports. But anchor supports are also calculated for the perception of significant tensions along wires and cables when some of them break in the adjacent span. Anchor supports are much more complicated and more expensive than intermediate ones, and therefore their number on each line should be minimal.

In the worst conditions are the end anchor supports installed at the exit of the line from the power plant or on the approaches to the substation. These supports experience one-sided tension of all wires from the side of the line, since the tension of wires from the side of the substation portal is insignificant.

2. Intermediate straight supports are installed on straight sections of overhead lines to maintain the wire in the anchor span. An intermediate support is cheaper and easier to manufacture than an anchor one, since, due to the equal tension of the wires on both sides, it does not experience forces along the line with unbroken wires, that is, in normal mode. Intermediate supports make up at least 80-90% total number VL supports.

3. Angle supports set at the turning points of the line.

In addition to the loads perceived by the intermediate straight supports, the loads from the transverse components of the tension of the wires and cables also act on the corner supports. Most often, at angles of rotation of lines up to 20 °, angled anchor-type supports are used (see Fig. 1.). At angles of rotation of the power line of more than 20 °, the weight of the intermediate corner supports increases significantly.

Rice. 1. Scheme of the anchor span of the overhead line and the span of the intersection with the railway.

4. Wooden poles are widely used on overhead lines up to 110 kV inclusive. Wooden poles have also been developed for 220 kV overhead lines, but they are not widely used. The advantages of these supports are low cost (in areas with forest resources) and ease of manufacture. The disadvantage is the susceptibility of wood to decay, especially at the point of contact with the soil. Effective remedy against decay - impregnation with special antiseptics.

Supports are made in most cases composite. The leg of the support consists of two parts of a long (rack ) and short (stepson). The stepson is connected to the rack with two bandages made of steel wire. Anchor and intermediate corner supports for 6-10 kV overhead lines are made in the form of an A-shaped structure.

The intermediate support is a portal having two racks with wind connections and a horizontal traverse. Anchor corner supports for V L 35-110 kV are made in the form of spatial A-P-shaped structures.

5. Metal poles (steel) used on power lines with a voltage of 35 kV and above, rather metal-intensive and require painting during operation to protect against corrosion. Install metal supports on reinforced concrete foundations. The most common design supports 500 kV - guyed portal (Fig. 2). For the 750 kV line, both portal poles on guys and V-shaped poles of the Nabla type with split guys are used. For use on 1150 kV lines under specific conditions, a number of tower designs have been developed - portal, V-shaped, with a cable-stayed traverse. The main type of intermediate supports for 1150 kV lines are V-shaped supports on guys with a horizontal arrangement of wires (Fig. 2). A DC line with a voltage of 1500 (±750) kV Ekibastuz-Center is designed for metal supports ah (fig.2) .

Fig.2. Metal supports:

a - intermediate single-circuit on braces 500 kV;b - intermediate V-shaped 1150 kV;in - intermediate support of 1500 kV direct current overhead line;G - elements of spatial lattice structures

6. Reinforced concrete poles are more durable than wooden poles, require less metal than metal poles, are easy to maintain and therefore are widely used on overhead lines up to 500 kV inclusive. The unification of the structures of metal and reinforced concrete supports for 35-500 kV overhead lines was carried out. As a result, the number of types and designs of supports and their parts has been reduced. This made it possible to mass-produce supports at factories, which accelerated and cheapened the construction of lines.

Support types

Overhead power lines. Support structures.

Supports and foundations for overhead power lines with a voltage of 35-110 kV have a significant share both in terms of material consumption and in terms of cost. Suffice it to say that the cost of the mounted support structures on these overhead lines is, as a rule, 60-70% of the total cost of the construction of overhead power lines. For lines located on industrial enterprises and the territories immediately adjacent to them, this percentage may be even higher.

Overhead line supports are designed to support line wires at a certain distance from the ground, ensuring the safety of people and reliable operation of the line.

Overhead power line towers are divided into anchor and intermediate. The supports of these two groups differ in the way the wires are suspended.

Anchor supports completely perceive the tension of wires and cables in spans adjacent to the support, i.e. serve to stretch the wires. On these supports, the wires are suspended with the help of hanging garlands. Anchor type supports can be of normal and lightweight construction. Anchor supports are much more complicated and more expensive than intermediate ones, and therefore their number on each line should be minimal.

Intermediate supports do not perceive the tension of the wires or perceive it partially. On the intermediate supports, the wires are suspended with the help of insulators supporting garlands, fig. one.

Rice. one. Scheme of the anchor span of the overhead line and the span of the intersection with the railway

On the basis of anchor supports can be performed end and transposition supports. Intermediate and anchor supports can be straight and angled.

End anchor supports installed at the exit of the line from the power plant or at the approaches to the substation are in the worst conditions. These supports experience one-sided tension of all wires from the side of the line, since tension from the side of the substation portal is insignificant.

Intermediate lines supports are installed on straight sections of overhead power lines to support wires. An intermediate support is cheaper and easier to manufacture than an anchor one, since in normal mode it does not experience forces along the line. Intermediate supports make up at least 80-90% of the total number of overhead line supports.

Angle supports are set at the turning points of the line. At angles of rotation of the line up to 20 °, angled anchor-type supports are used. At angles of rotation of the power line more than 20 ° - intermediate corner supports.

On overhead power lines are used special supports the following types: transpositional- to change the order of the wires on the supports; branch- to carry out branches from the main line; transitional- for crossing rivers, gorges, etc.

Transposition is used on lines with a voltage of 110 kV and above with a length of more than 100 km in order to make the capacitance and inductance of all three phases of the overhead power transmission line circuit the same. At the same time, the relative position of the wires in relation to each other is consistently changed on the supports. However, such a triple movement of wires is called a transposition cycle. The line is divided into three sections (steps), in which each of the three wires occupies all three possible positions, fig. 2.

VL supports are designed to provide the required distances between the phases and the ground. The horizontal distance between the centers of two adjacent supports of the same line is called the span. There are transitional, intermediate and anchor spans. The anchor span usually consists of several intermediate spans.

Support types

According to the number of chains, the supports are classified into single-chain and double-chain. An overhead line with two circuits, made on double-circuit supports, is cheaper than two parallel lines, made on single-circuit supports, and can be built in a shorter time.

VL supports are divided into two main groups: intermediate and anchor. In addition, corner, end and special supports are distinguished.

Intermediate supports are installed on straight sections of the route. In normal mode, they perceive vertical loads from the mass of wires, insulators, fittings and horizontal loads from wind pressure on wires and supports. When one or more wires break, the intermediate supports take on an additional load directed along the line and are subjected to torsion and bending. Therefore, they are made with a certain margin of safety. The number of intermediate supports on overhead lines is up to 80%.

Anchor supports are installed on straight sections of the route for the passage of overhead lines through engineering structures or natural obstacles. Their design is stiffer and stronger, as they perceive the longitudinal load from the difference in tension of wires and cables in adjacent anchor spans, and during installation - from the tension of wires suspended from one side.

Rice. 2.1. Plan and profile of the VL section:

A - anchor support, P - intermediate support, UP - angular intermediate support, UA - corner anchor support, KA - end anchor support

End supports are a type of anchor and are installed at the end and beginning of the line. Under normal operating conditions, they perceive the load from the one-sided pull of the wires.

Specialized ones include transposition supports, the design of which allows you to change the order of the wires on the support; branch lines - for branching off the main line, etc.

Support material

According to the technological design standards for overhead power lines with a voltage of 35 kV and above, the following areas of use are recommended various materials for making supports.

wooden supports(pine, winter larch, for non-critical parts - spruce, fir) impregnated with an antiseptic are used for single-circuit overhead lines 35 - 150 kV where the use of wood is economically beneficial. The advantage of wooden poles is due to their low cost, sufficiently high mechanical strength, high electrical insulating properties, and low cost. Main disadvantage- fragility.

Reinforced concrete supports are used in flat terrain for single-circuit lines 35 - 220 kV, on all double-circuit lines - 35 - 110 kV, on overhead lines - 500 kV, passing in a flat area where metal supports are not economically feasible. Reinforced concrete supports are not allowed to be used on overhead lines passing in mountainous or rugged terrain. Reinforced concrete supports have high mechanical strength, are durable, cheap to operate, manufacture and assemble compared to metal ones. Their disadvantage is their large mass, which increases fare. In reinforced concrete supports, the main tensile forces are perceived by steel reinforcement, since concrete does not work well in tension, but during compression, the main loads are perceived by concrete.

The joint work of concrete and steel is due to the following properties. Concrete during hardening is firmly bonded to reinforcement due to gluing and friction caused by shrinkage of concrete during hardening, resulting in compression of reinforcement bars by concrete. As a result, when exposed to external forces, both materials work together, adjacent sections of concrete and steel receive the same deformations. Steel and concrete have approximately the same coefficients of linear expansion, which eliminates the appearance internal stresses in reinforced concrete with changes outdoor temperature. Concrete reliably protects reinforcement from corrosion and perceives compressive stress during temperature fluctuations. The disadvantage of reinforced concrete is the formation of cracks in it, especially at the points of contact with the ground. To increase crack resistance, prestressing of reinforcement is used, which creates additional compression of concrete. The main elements of reinforced concrete supports are racks, traverses, cable racks and crossbars. At reinforced concrete plants, racks are made either on centrifuges that perform concrete shaping and compaction, or by vibrating, compacting the concrete mixture with vibrators. By centrifugation, round hollow conical and cylindrical racks are made, by vibration - rectangular (GOST 22387.0-85). For double-circuit overhead lines with a voltage of more than 35 kV and above, centrifuged racks are used, labeled SK (conical racks) and STs (cylindrical racks). SK racks are used on 35-750 kV overhead lines of two types: 22.6 m and 26 m long with upper and lower diameters of 440/650 mm and 416/650 mm, respectively, made in one unified formwork. STs racks are made with a length of 20 m and a diameter of 800 mm. For 35 kV overhead lines, vibration-resistant CBs with a length of 16.4 m are used.

Metal supports are used on double-circuit overhead lines 35-500 kV, on single-circuit overhead lines 110, 220, 330 kV, where it is impossible or impractical to use reinforced concrete supports, on overhead lines 750 kV. The main structures of metal supports are made of St3 steel, the most stressed support units are made of low-alloy steels. Parts of the supports are factory hot-dip galvanized. The poles are assembled using bolted connections. Their advantage over reinforced concrete is that they allow you to create structures designed for heavy loads and any climatic conditions, have high mechanical strength with a relatively small mass. However, they are quite expensive and subject to corrosion. Steel supports can be single-column (tower) and portal in design, and free-standing or with braces according to the method of fixing on foundations.

Unification of supports

Based on the results of many years of practice in the construction and operation of overhead lines, the most appropriate and economical types and designs of supports are determined and their unification is systematically carried out, which allows the use of a single convenient system of designations and classifications. Unification makes it possible to reduce the total number of types of supports, the number of standard sizes of support parts, to select, if necessary, a rational replacement for supports or their parts, and to organize their mass production at specialized plants. According to the unification, for each type of support, the conditions for use are established: voltage of overhead lines, number of circuits, ice area, maximum wind speed, ranges of wire brands, cable brands. The last unification for steel poles was carried out in 1995-96, according to it, the range of applied wire cross-sections was expanded, which allows for optimal current density, the lengths of insulator strings were unified, recommendations were developed to take into account the degree of atmospheric pollution when choosing insulators, changes were made to the design of poles , the names of support types have been changed. According to these conditions, the appropriate type of support is selected in the reference books, the name of which reflects the following features:

1) type of support: P - intermediate, U - angular (intermediate or anchor), C - specialized;

2) support material: D - wood, B - reinforced concrete, for metal supports letter designation is absent;

3) rated voltage of overhead lines;

4) standard size - this is a figure that reflects the strength properties of the support: an even number is assigned to a double-chain support, an odd number is assigned to a single-circuit one.

For example, PB35-3 is an intermediate reinforced concrete single-circuit support for 35 kV overhead lines (intended for the construction of overhead lines in III-IV regions on ice, wind speeds up to 30 m / s, with AS95 / 16-AC150 / 24 wires and TK-35 cable ).

The most important characteristics VL, depending on the type of support, are the concepts of overall and overall span. Dimension G is the smallest allowable PUE, the vertical distance between the lowest point of sagging of the wire to the crossed engineering structures or the surface of the earth or water. The dimension values ​​are determined from considerations safe operation VL (Table 2.1).

Table 2.1

The overall span is a span determined by the condition of the permissible distance from the wires to the ground, provided that the supports are installed on an ideal flat surface. The values ​​of the overall spans are indicated in the technical characteristics of the supports.

Construction of overhead power lines

Support structure

The structures of overhead power transmission line poles are very diverse and depend on the material from which the pole is made (metal, reinforced concrete, wood, fiberglass), the purpose of the pole (intermediate, angular, transpositional, transitional, etc.), on local conditions on the line route ( populated or uninhabited areas, mountainous conditions, areas with swampy or soft soils, etc.), line voltages, number of circuits (single circuit, double circuit, multi circuit), etc.

In the design of many types of supports, the following elements can be found:

1. Rack - is the main integral element of the support structure, unlike other elements that may be absent. The rack is designed to provide the required dimensions of the wires (wire gauge - the vertical distance from the wire in the span to the engineering structures intersected by the route, the surface of the earth or water). There can be one, two, three or more posts in the support structure.

a	b

Picture. VL supports: a - two-column support; b - three-post support.

A rack of lattice-type metal supports is called a trunk. The barrel is usually a tetrahedral truncated lattice pyramid made of rolled steel profiles (corner, strip, sheet), and consists of a belt, a lattice and a diaphragm. The lattice, in turn, has rods-braces and spacers, as well as additional connections.



Picture. Structural elements of a metal support: 1 - support post belt; 2 - rods-braces forming a rack lattice; 3 - diaphragm; 4 - traverse; 5 - cable rack.

2. Struts - used for corner, end, anchor and branch supports of overhead lines with voltage up to 10 kV. They take on part of the load of the support from the one-sided tension of the wire.



Picture. Corner support with two struts: 1 - rack; 2 - brace.

3. Attachment (stepson) - partially buried in the ground, the lower part of the structure of the combined support of overhead lines with a voltage of up to 35 kV, consisting of wooden racks and reinforced concrete attachments.
4. Braces are inclined support elements that serve to reinforce its structure and connect several support elements to each other, for example, a post with a traverse, or two support posts.



Picture. Structural elements of the combined support: 1 - wooden rack supports; 2 - reinforced concrete prefix (stepson); 3 - brace; 4 - traverse.

5. Traverse - provides fastening of the wires of the power line at a certain (permissible) distance from the support and from each other.

Picture. Support traverses: a - for reinforced concrete supports 10 kV; b - for reinforced concrete supports 110 kV.

Most often you can find traverses in the form of a rigid metal structure, however, there are also wooden traverses and traverses made of composite materials.



Picture. 110 kV overhead line support traverse made of composite materials

In addition, so-called flexible traverses can be found on V-shaped supports of the "nabla" type and U-shaped supports.



Picture. VL support with a "flexible" traverse

In some pole designs, traverses may be absent, for example, for wooden or reinforced concrete poles of overhead lines with a voltage of up to 1 kV, for poles of overhead lines with self-supporting insulated wires voltage up to 1 kV, for anchor supports of overhead lines of any voltage, where each phase is mounted on a separate rack.



Picture. Support without traverse

6. Foundation - a structure embedded in the ground and transferring loads to it from the support, insulators, wires and external influences(ice, wind).



Picture. Mushroom reinforced concrete foundation

For single-rack supports, in which the lower end of the rack is embedded in the ground, the bottom of the rack serves as the foundation; for metal supports, pile or prefabricated mushroom-shaped reinforced concrete ones are used, and when installing transitional supports and supports in swamps, monolithic concrete foundations are used.



Picture. Reinforced concrete piles used in single-pile and multi-pile foundations of overhead lines



Picture. Power transmission line support on a pile foundation

7. Rigel - increases side surface underground construction of reinforced concrete racks and footboards of metal supports. Crossbars increase the ability of the foundation to withstand horizontal loads acting on the support, preventing it from tipping over from the forces of tension of the wires when constructing supports in soft soil.



Picture. Mushroom reinforced concrete foundation (1) with three crossbars (2)

8. Guys - designed to increase the stability of the supports and perceive the forces from the tension of the wire.



Picture. Support secured with braces

The upper part of the guy is attached to the post or traverse of the support, and the lower part to the anchor or reinforced concrete slab. In addition, the design of the brace may include a tension coupling - a lanyard.

Picture. Lower part of the brace

9. Rope rack - top part support designed to support the lightning protection cable. Usually it is a trapezoidal spire at the top of the support. On the support there can be one or two cable racks (on U-shaped supports), there are also supports without a cable rack.

Power lines (TL) are one of the critical components contemporary electrical network. A transmission line is a system of power equipment that goes beyond power plants and is designed for the remote transmission of electricity through electric current.

Power lines are divided into cable and air. Cable power line is a power line made by one or more cables laid directly into the ground, cable channels, pipes, cable structures. aerial power line (VL) is a device designed for transmission and distribution electrical energy through wires that are in the open air.

For the installation of overhead power lines, special structures are used - overhead power line supports. Power transmission towers are special facilities designed to hold the wires of overhead power lines at a given distance from the surface of the earth and from each other.

The pylon system of overhead power lines was developed at the beginning of the 20th century, when the first powerful power plants began to appear, and it became possible to transmit electricity over long distances. Until the middle of the 20th century, the rolling of wires for power transmission towers took place on the ground. But this method of rolling out had many disadvantages: the wire dragged along the ground received numerous damages and required repair already during the installation process. Small scratches and chips caused a corona discharge, leading to losses in the transmitted energy.

In the fifties of the twentieth century in Europe, a special method of installing electrical wires was developed - the so-called pull method. The pulling method involves rolling the wire directly onto the installed power transmission towers using special rollers, without lowering the wire to the ground. A tensioning machine is installed at one end of the air line, and a brake machine at the other. Thanks to this method, during the construction of power transmission lines, the possibility of damage to electrical wires was significantly reduced and repair costs were reduced, which, in turn, led to a reduction in losses of transmitted electricity. The advantage of this method is also expressed in the fact that the presence of natural (rivers, lakes, forests, mountains, etc.) and artificial (roads and railways, buildings, etc.) barriers facilitates and speeds up the installation of power lines. In Russia, the technology of mounting power transmission line poles "under tension" has been used since 1996 and is currently the most appropriate and popular way of erecting overhead power transmission poles.

AT modern construction Power transmission towers are also used as supports for holding grounded lightning rods and fiber optic communication lines. They are also used as space lighting on highways, streets, squares, etc. during the dark hours of the day. VL poles are designed for power transmission line structures at a design outdoor temperature of up to -65˚С inclusive.

Supports are divided into two main groups, depending on the method of suspension of wires:

• intermediate power transmission towers. The wires on these supports are fixed in supporting clamps;
• anchor type supports. Wires on anchor-type supports are fixed in tension clamps. These supports are used to pull the wires.

Two main groups are divided into types with special purposes:

• intermediate straight supports. They are installed on straight sections of the line and are intended to support wires and cables and are not designed for loads from the tension of wires along the line. On intermediate supports with suspension insulators, the wires are fixed in special supporting garlands, which are located vertically. On supports with pin insulators, the wires are fastened by wire knitting. Intermediate straight supports perceive horizontal loads from wind pressure on the wires and on the support, and vertical - from the weight of the wires and the own weight of the power transmission line support;
• intermediate corner supports. They are installed at the corners of the line with a suspension of wires in supporting garlands. In addition to the loads that act on the intermediate straight supports, the intermediate supports also perceive loads from the transverse components of the tension of the wires and cables;
• anchor-angle supports. They are installed at power line rotation angles of more than 20˚, have a more rigid structure than intermediate corner supports and are designed for significant loads;
• anchor supports. Special anchor supports are installed on straight sections of the route for crossing engineering structures or natural barriers. Perceive the longitudinal load from the tension of wires and cables;
• end supports. They are a type of anchor supports, installed at the end or beginning of power lines and are designed to absorb loads from one-sided tension of wires and cables;
• special supports, which include: transposition - serve to change the order of the wires on the supports; branch lines - for the device of branches from the main line; cross - used when crossing overhead lines in two directions; anti-wind - to enhance the mechanical strength of overhead lines; transitional - when crossing overhead lines through engineering structures or natural barriers.

According to the method of fixing in the ground, the pores are divided:

According to the design of the power transmission line supports are divided into:

• free-standing supports. In turn, they are divided into single rack and multirack;
• supports with braces;
• cable-stayed supports of emergency reserve.

Power transmission towers are divided into supports for lines with a voltage of 0.4, 6, 10, 35, 110, 220, 330, 500, 750, 1150 kV. These groups of supports differ in size and weight. The more voltage passing through the wires, the higher and heavier the support. The increase in the size of the support is caused by the need to obtain the required distances from the wire to the body of the support and to the ground, corresponding to the PUE (Electrical Installation Rules) for various line voltages.

According to the material of manufacture, power transmission towers are divided into wooden, metal and reinforced concrete. The choice of the type of power transmission towers is usually based on the availability of appropriate materials in the area of ​​​​the construction of the power line, economic feasibility and technical specifications object under construction. Wooden poles are used for lines with low voltage, up to 220/380 V. However, with such advantages as low cost and ease of manufacture, wooden poles have significant drawbacks: wooden poles are short-lived (service life is 10 - 25 years), do not have high strength, the material reacts sharply to changes in climatic conditions.

Metal poles are much stronger than wooden poles, but they require constant maintenance - the surface of structures and connecting elements must be periodically painted or galvanized to prevent oxidation or corrosion.

High strength and resistance of the material to deformation, corrosion and abrupt climate change, long service life of structures (about 50-70 years), fire resistance, high manufacturability and low cost are among the few reasons that allow us to say that reinforced concrete is the most appropriate solution for production power transmission towers in Russia. Indeed, in a country with a huge area and a diverse climate, there is a need not only for in large numbers extended communication lines, but also in high reliability in conditions of a sharp change weather conditions and humidity level. Availability of high-quality reinforced concrete poles for power lines - essential condition ensuring stability in the operation of the electric power industry. The Blok group of companies manufactures and supplies to the construction market only high-quality products from, in strict accordance with GOST and SNiP.

Reinforced concrete racks of power transmission line supports are divided into two types according to the manufacturing method.

• vibrated support legs. A manufacturing method in which the concrete mixture is subjected to vibration during pouring into the mold, which ensures an increase in the density and uniformity of concrete with less cement consumption. They are made from both prestressed and unstressed reinforced concrete and are used as racks and struts in power transmission line supports with voltage up to 35 kV, as well as lighting poles;
• centrifuged supports. Cooking Method concrete mix, at which a uniform distribution of the mixture is ensured, therefore, each section is completely compacted. Centrifuged tower racks are designed for power lines with a voltage of 35-750 kV.

Structurally, reinforced concrete power transmission line supports are elongated racks with different sections depending on the expected operating conditions and loads. The design of the supports also implies the presence of embedded parts for installing clamps, traverses and fasteners for rigid or hinged fastening of wires, as well as plates to increase the load-bearing function of products.

According to the type of construction, reinforced concrete supports are divided into the main types:

• cylindrical rack supports;
• conical poles.

Reinforced concrete pylons for power transmission lines are represented by a wide range.

For high-voltage power lines, centrifuged cylindrical and conical poles are manufactured in accordance with GOST 22687.2-85 "Cylindrical reinforced concrete centrifuged poles for high-voltage power transmission line poles" and GOST 22687.1-85 "Conical reinforced concrete centrifuged poles for high-voltage power transmission line poles", respectively.

Vibrated racks are manufactured in accordance with GOST 23613-79 “Reinforced concrete vibrated racks for high-voltage transmission line supports. Specifications”, GOST 26071-84“ Vibrated reinforced concrete poles for overhead power transmission line supports with a voltage of 0.38 kV. Specifications” and series 3.407.1-136 “Reinforced concrete poles of 0.38 kV overhead lines” and 3.407.1-143 “Reinforced concrete poles of 10 kV overhead lines”.

Special two-column supports are manufactured in accordance with the series 3.407.1-152 "Unified designs of intermediate two-column reinforced concrete supports of 35-500 kV overhead lines."
Series 3.407.1-157 "Unified reinforced concrete products substations 35-500 kV "includes vibrated conical racks with a rectangular section, centrifuged cylindrical racks. Series 3.407.1-175" Unified designs of intermediate single-column reinforced concrete supports of overhead lines 35-220 kV "contains instructions for the manufacture of conical racks of supports.

Reinforced concrete centrifuged supports of the contact network and lighting are manufactured according to the series 3.507 KL-10 "Supports of the contact network and lighting".

As a material for the manufacture of reinforced concrete racks of power transmission line supports, a material resistant to electrocorrosion and corrosion from exposure is used. environment Portland cement various classes in terms of compressive strength, from B25. Fine-grained sand and gravel crushed stone are used as aggregates. For each project, a different option preparation of concrete mix: vibration is used for racks of power transmission line poles with voltage up to 35 kV and lighting poles, centrifugation - for power line poles with voltage of 35-750 kV. Concrete grades for frost resistance and water resistance are assigned depending on the operating conditions and climate in the construction area, from F150 and from W4, respectively. Additionally, special plasticizing and gas-entraining additives are added to the concrete of the pillars.

The concrete of the pillars of the power transmission line supports is reinforced with prestressed reinforcement to give greater strength to the products. All reinforcement parts and embedded products in without fail covered with a special substance against internal corrosion.

Steel of the following classes is used as working reinforcement:

• rod thermally hardened with a periodic profile of the class At-VI according to GOST 10884-71 during the operation of racks in the construction area with a design outdoor temperature of at least -55 ° C;
• rod hot-rolled periodic profile of classes A-IV and A-V. When the design temperature of the outside air is below -55 ° C, steel of these classes should be used in the form of whole rods of a measured length. Reinforcing wire of class B-I is used as transverse reinforcement. For the manufacture of clamps, grounding conductors and mounting loops, hot-rolled smooth reinforcing steel of class A-I is used.

Marking of racks in accordance with GOST 23613-79.

In the brand designation of the rack, letters and numbers mean: SV - vibrated rack; additional letters "a" and "b" - rack options, where:

• "a" - the presence in the racks of embedded products (pins) and holes for attaching wires;
• "b" - the presence of holes in the racks for attaching anchor plates;
• the number after the letters - the length of the rack in decimeters;
• the figure after the first dash is the calculated bending moment in ton-force meters;
• the figure after the second dash is the design grade of concrete for frost resistance.

For racks made of sulfate-resistant cement, the letter “c” is placed after the design grade of concrete for frost resistance.

For racks intended for use in areas with a calculated outdoor temperature below -40 ° C or in the presence of aggressive soils and ground water, the third group of the brand also includes the corresponding designations of characteristics that ensure the durability of the racks under operating conditions: M - for racks used in areas with an estimated outdoor temperature of -40 ° C;

For racks used in conditions of exposure to aggressive soils and groundwater - characteristics of the degree of density of concrete: P - increased density, O - especially dense.

According to GOST 22687.1-85 and GOST 22687.2-85, the rack brand consists of alphanumeric groups separated by a hyphen.

The first group contains the rack size designation, including:

letter designation of the rack type, where:

• SK - conical;
• SC - cylindrical;
• then the length of the rack is indicated in meters in integers.

The second group includes designations: the bearing capacity of the rack and the scope of its application in the support and the characteristics of the prestressing longitudinal reinforcement:

• 1 - for reinforcing steel class A-V or At-VCK;
• 2 - the same, class A-VI;
• 3 - for reinforcing ropes of class K-7 with mixed reinforcement;
• 4 - the same, class K-19;
• 5 - for reinforcing ropes of class K-7;
• 0 - for reinforcing steel class A-IV or At-IVK.

In the third group, if necessary, reflect additional characteristics (resistance to aggressive environments, the presence of additional embedded products, etc.).

Marking according to the series 3.407.1-136 for the structures of the support elements of 0.38 kV overhead lines consists of an alphanumeric designation.

The first part indicates the designation of the type of power transmission line support:

• P - intermediate;
• K - terminal;
• UA - corner anchor;
• PP - transitional intermediate;
• POA - transitional branch anchor;
• PC - cross.

In the second part - the standard size of the support: odd numbers for single-circuit supports, even numbers for eight- and nine-wire overhead lines.

Marking according to the series 3.407.1-143 for supports of 10 kV overhead lines has in the first part the letter designation of the type of support:

• P - intermediate;
• OA - branch anchor;
• Etc.

In the second part - the digital index 10, indicating the voltage of the overhead line.

In the third part, through a dash, the support standard size number is written.

Support elements, which include plates and anchors, are marked with an alphanumeric designation. P - plate, AC - cylindrical anchor.

A hyphen indicates the product size number.

The marking of reinforced concrete intermediate single-column supports according to the 3.407.1-175 series and two-column supports according to the 3.407.1-152 series consists of an alphanumeric designation.

The first digit means the ordinal number of the region in which the support is applied;

The subsequent combination of letters is the type of support:

• PB - intermediate concrete;
• PSB - intermediate special concrete;
• The next group of numbers is the voltage of the overhead line in kV, in the dimensions of which the support is made;
• The number following the dash is the serial number of the power transmission line support, in unification, while odd numbers belong to single-circuit supports, and even numbers belong to double-circuit ones.

Marking of products of supports according to the series 3.407.1-157:

The first group of alphanumeric designation includes the letters of the conditional name of the products and the main dimensions in decimetres, where:

• BC - vibrated rack.

The second group, through a hyphen, denotes bearing capacity in kN.m;

The third group, through a hyphen, denotes design features (reinforcement option, the presence of additional embedded parts).

The marking of supports of the 3.407-102 series includes the following items:

• STsP - cylindrical hollow stand;
• BC - vibrated rack;
• VSL - vibrated rack for lighting lines and railway networks;
• This is followed by a number indicating the size of the product.

The marking of the supports of the contact network and lighting according to the 3.507 KL-10 series consists of alphanumeric designations.

Centrifuged power transmission towers (Issue 1-1):

• OKC - outdoor lighting poles with cable supply;
• ОАЦ - anchor supports for outdoor lighting with air supply;
• OPTS - intermediate outdoor lighting poles with air supply;
• OSC - combined supports of the contact network and outdoor lighting with cable power supply.

The first digit after the letters, through a hyphen, indicates the horizontal standard load on the support in centners, the second - the length of the support in meters.

Vibrated supports (issues 1-2, 1-4, 1-5):

• SV - stand vibrated outdoor lighting with cable or air supply;
• The number following after the letters indicates the standard bending moment in the seal, in tm;
• The second digit, separated by a hyphen, indicates the length of the rack in meters.

Unstressed Vibrated Racks (Issue 1-6):

• The first group contains the letter designation of the type of construction, CB - vibrated stand, and numerical - the length of the stand in decimeters;
• The second group - symbol bearing capacity.