What are electrical poles called? Let's make support of power lines. Wooden power line poles

Supports of high-voltage power lines are used for reliable fastening and the necessary tension of electrical wires, through which the electrical energy generated by power plants is transmitted to consumers over long distances.

According to their purpose and the applied method of fastening electrical wires, power transmission towers are:

• intermediate type;
• anchor type;
• angular type;
• end type;
• special type.

Each type of these supports has its own design and functional features and can be used in certain situations in accordance with its purpose.

Intermediate power line supports

They are the most common type of supports used for the installation of high-voltage power lines. Electric wires are attached to them in special supporting clamps in the form of vertically located suspension insulators that perceive horizontal loads from the weight of wires and cables and wind action. They are not designed for the longitudinal force from the tension of the wires between the supports. Such supports are installed on straight sections and at small angles of rotation of the main routes of power lines.

Anchor supports for power lines

They provide fastening of electrical wires with their longitudinal adjustable tension using special tensioning devices. The design of this type of supports is characterized by increased rigidity and special strength, since in addition to transverse horizontal and vertical loads, they are also subjected to a longitudinal horizontal load corresponding to the tension force of the wires. This type of supports is used on straight sections of power lines when they cross natural barriers or engineering structures, as well as at places where the direction of main routes changes at large angles of rotation (more than 30 degrees).

Power line corner poles

Are applied in places of change of the direction of the main power lines. For small angles of rotation (up to 20–30 degrees), which provide a small load on the structural elements, intermediate-type angular supports are used. At large angles of rotation, angled ones with an anchor type of wire fastening are used.

Power line end towers

They are installed at the beginning and end of high-voltage power lines to connect the main and intermediate transformer substations and electricity consumers. They use an anchor type of fastening of electrical wires, which ensures their one-sided tension.

Special power transmission towers

They are used in certain situations and in turn are divided into:

• transposition supports that allow you to change the order of the location of electrical wires in power lines;
• branch supports providing connection of additional branches from the main route;
• cross supports used in the case of mutual intersection of power lines in different directions;
• transmission towers of power transmission lines used when crossing power lines with natural barriers or various engineering structures.

Depending on the maximum allowable power of electricity transmitted over a high-voltage line to consumers, the poles are classified into the following categories:

• power line supports 35 kV;
• power line supports 110 kV;
• power line supports 220 kV;
• power line supports 330 sq.

The higher the power transmitted through the high-voltage line of electricity, the larger the cross section and weight of the electrical wires used in this case, and the stronger and more reliable the design of the supports should be.

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Types of power transmission towers

Types of overhead lines

Services for the manufacture of metal structures of power transmission line supports, the production of metal products, metalworking services to order are provided by the company "Skhid-budkonstruktsiya", Ukraine.

What types of power transmission towers exist?

In the production of metal structures for power transmission lines, blowing types of overhead line supports are distinguished: intermediate power transmission line supports, power transmission line anchor supports, power transmission line corner supports and special metal products for power transmission lines. Varieties of types of structures of overhead power lines, which are the most numerous on all power lines, are intermediate supports that are designed to support wires on straight sections of the route. All high-voltage wires are attached to power transmission traverses through supporting insulator garlands and other structural elements of overhead power lines. In normal mode, this type of overhead line supports perceive loads from the weight of adjacent half-spans of wires and cables, the weight of insulators, linear fittings and individual support elements, as well as wind loads due to wind pressure on wires, cables and the metal structure of the power transmission line itself. In emergency mode, the structures of intermediate supports of power transmission lines must withstand the stresses that occur when one wire or cable breaks.

The distance between two adjacent intermediate supports of the overhead line is called the intermediate span. Corner supports VL can be intermediate and anchor. Intermediate corner elements of power transmission lines are usually used at small angles of rotation of the route (up to 20 °). Anchor or intermediate corner elements of power transmission lines are installed in sections of the line route where its direction changes. Intermediate corner supports of overhead lines in normal mode, in addition to loads acting on ordinary intermediate elements of power lines, perceive the total effort from the tension of wires and cables in adjacent spans, applied at the points of their suspension along the bisector of the angle of rotation of the power line. The number of anchor corner supports of overhead lines is usually a small percentage of the total number on the line (10 ... 15%). Their use is determined by the conditions of installation of lines, the requirements for the intersection of lines with various objects, natural obstacles, i.e. they are used, for example, in mountainous areas, and also when intermediate corner elements do not provide the required reliability. Anchor corner supports are also used as terminal ones, from which the wires of the line go to the switchgear of the substation or station. On lines passing in populated areas, the number of anchor corner elements of power lines also increases. The wires of the overhead line are fastened through the tension garlands of insulators. In normal mode, in addition to the loads indicated for the intermediate elements of the stucco, these stud supports are affected by the difference in tension along the wires and cables in adjacent spans and the resultant of the gravitational forces along the wires and cables. Usually, all anchor-type supports are installed so that the resultant of the gravitational forces is directed along the axis of the support traverse. In emergency mode, the anchor posts of power lines must withstand the breakage of two wires or cables. The distance between two adjacent anchor supports of a power line is called an anchor span. Branching elements of power transmission lines are designed to carry out branches from main overhead lines, if necessary, to supply electricity to consumers located at some distance from the route. Cross elements are used to cross wires of overhead lines in two directions on them. End posts VL are installed at the beginning and end of the overhead line. They perceive the forces directed along the line, created by the normal one-sided tension of the wires. For overhead lines, power transmission line anchor supports are also used, which have increased strength compared to the types of racks listed above and a more complex design. For overhead lines with voltages up to 1 kV, reinforced concrete racks are mainly used.

What are power transmission towers? Classification of varieties

According to the method of fixing in the ground, they are classified:

VL supports installed directly into the ground - Power transmission line supports installed on foundations Varieties of power transmission line supports by design:

Free-standing power line poles - Guyed poles

By the number of circuits, power transmission towers are classified:

Single circuit - Double circuit - Multi circuit

Unified transmission line poles

Based on many years of practice in the construction, design and operation of overhead lines, the most appropriate and economical types and designs of supports for the corresponding climatic and geographical regions are determined and their unification is carried out.

Designation of power transmission towers

What types of supports are used for the construction of vl?

For metal and reinforced concrete supports of 10 - 330 kV overhead lines, the following designation system is adopted.

P, PS - intermediate supports

PVS - intermediate supports with internal connections

PU, PUS - intermediate corner

PP - intermediate transitional

U, US - anchor-angular

K, KS - terminal

B - reinforced concrete

M - Polyhedral

How are overhead lines marked?

The numbers after the letters in the marking indicate the voltage class. The presence of the letter "t" indicates a cable rack with two cables. A hyphenated number in the marking of overhead line supports indicates the number of circuits: odd, for example, a unit in the numbering of a power transmission line support is a single-circuit line, an even number in the numbering is two and multi-circuit. The number through "+" in the numbering means the height of the attachment to the base support (applicable to metal).

For example, symbols for VL supports: U110-2 + ​​14 - Metal anchor-angled double-chain support with a stand of 14 meters PM220-1 - Intermediate metal multifaceted single-chain support U220-2t - Metal anchor-angle PB110-4 - Intermediate reinforced concrete

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CLASSIFICATION OF POWER LINE SUPPORTS BY GENERAL VIEW

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Elektro - Types of supports

TYPES OF SUPPORTS

Supports are anchor (including end), intermediate, corner, transposition and special. The use of one or another type of supports is dictated by their purpose, which in turn depends on the location of the supports on the route of the overhead line.

Anchor supports are installed for rigid fastening of wires at especially critical points of the line (at the ends of the line, at the ends of its straight sections, at the intersections of especially important engineering structures and large reservoirs). Anchor supports must withstand the one-sided pull of two wires. 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 the wires from the side of the portal is insignificant.

Rice. 1. Anchor wooden support of the line with a voltage of 110 kV.

On fig. 1 shows a wooden anchor support for 110 kV transmission lines, intended for straight sections of the route.

Anchor supports are much more complicated and more expensive than intermediate ones, and therefore their number on each line should be minimal. On straight sections of lines with voltages above 1000 V with blind clamps, the distance between anchor supports practically reaches 10-15 km and is not limited by standards.

Intermediate supports (Fig. 2 and 3) serve to support the wire on straight sections of the line in the anchor span. The intermediate support is cheaper than other types of supports and easier to manufacture, since, due to the same tension of the wires on both sides, it does not experience forces along the line in normal mode (i.e., with unbroken wires). A characteristic feature of intermediate supports is their mass character; they make up at least 80-90% of the total number of overhead line supports. That is why, when designing overhead lines, special attention should be paid to choosing the most economical type of intermediate supports.

Rice. 2. Intermediate wooden support on a cableless line with a voltage of 110 kV.

Rice. 3. Intermediate free-standing metal support of a double-circuit line with a voltage of 220 kV.

Corner supports are installed at the turning points of the line. The angle of rotation of the line is the angle α (Fig. 4), additional up to 180 ° to the internal angle β of the line. The traverses of the corner support are installed along the bisector of the angle β.

Most often, angled anchor supports are used (Fig. 5, a). At angles of rotation up to 60°, it is possible to install single-column reinforced concrete supports with braces (Fig. 5, b), and at angles of rotation up to 20° and an even profile of the route, it is allowed to use intermediate supports instead of corner ones, respectively changing the method of fixing the wires.

Rice. 4. The angle of rotation of the power line: 1 - legs of the support; 2 - traverse; 3 - loop.

Rice. 5. Corner supports: a - anchor portal on a 220 kV line; b - single-column reinforced concrete with braces on a single-circuit line with a voltage of 110 kV.

Transposition supports are used for transposition of wires. On fig. 6 shows a transposition support of a single-circuit line with a voltage of 220 kV, and in fig. 7 - transposition of wires on a support of a double-circuit line.

Rice. 6. Transposition support of a single-circuit line with a voltage of 220 kV.

Rice. 7. Transposition of wires on a support of a double-circuit line.

Special supports are of two types: transitional (Fig. 8) - for large spans (crossings of rivers, gorges, lakes, etc.) and branching (Fig. 9) - when a deaf branch from the line is required.

Rice. 8. Transition support.

Rice. 9. Branch pole of a double-circuit line with a voltage of 110 kV.

According to the material of manufacture, overhead line supports are wooden, reinforced concrete and metal.

Wooden poles are easy to make and cheap.

In our country they are made from pine, larch. The disadvantage of these supports is their fragility, due to the decay of wood, i.e., its destruction by special fungi. The most susceptible to damage are the lower parts of the pillars dug into the ground, as well as cuts in the tree and bolted joints. The service life of those parts of the poles made of untreated pine, which are located at the surface of the earth, is on average 3-5 years. The service life of wooden supports can be increased if the finished wooden parts are impregnated with antiseptics (creosote, anthracene oil) and thus prevent the development of fungi in the wood. Factory impregnation increases the service life of wooden poles up to 15-20 years.

Wooden poles are used in the construction of single-circuit lines with voltage up to 220 kV inclusive. For economic reasons, the supports are made in most cases composite. The support leg consists of two parts: long (main rack) and short (stepson). The stepson is connected to the rack with two bandages made of steel wire with a diameter of 4-6 mm. To stretch the bandage, metal plates are used, pulled together by through bolts. The contacting places of the stepson and the main rack are hemmed so that they fit snugly together. The stepson is buried in the ground to a depth of 1.8 m for transmission line supports with a voltage of up to 10 kV and 2.5 m for lines of 35-220 kV.

Rice. 10. Single-column wooden poles of cableless lines with a voltage of 6-10 kV (dimensions in meters).

Wooden supports for transmission lines with voltage up to 10 kV are made single-column, insulators are fixed on hooks (Fig. 10, a). For wires of medium cross sections, insulators are mounted on pins (Fig. 10, b). On lines with a voltage of 110 kV and on most lines with a voltage of 35 kV, two-rack U-type supports are installed (see Fig. 2).

Wooden poles for power lines are used mainly in areas rich in timber, where air humidity is negligible and the average annual temperature does not go beyond 0 to + 5 ° C. To increase the service life of wooden poles, they are made mainly with reinforced concrete stepchildren. In peaty and soft soils, reinforced concrete piles are used as stepchildren.

Reinforced concrete poles are more durable than wooden poles, require less metal than metal poles, are easy to maintain and therefore have recently been widely used on power lines of all voltages up to 500 kV inclusive.

On single-circuit lines with a voltage of 6-10 kV, single-column free-standing supports made of vibrated concrete, rectangular in section, are used. The wires are mounted on pin insulators mounted on a horizontal metal traverse and a vertical post welded to it (upper wire). Single-column supports for 35 kV lines with a large wire cross section and for 110-330 kV lines are made of centrifuged concrete, with metal traverses. Single-column supports are both free-standing (Fig. 11) and guyed (Fig. 12).

Rice. 11. Single-column free-standing reinforced concrete support of a double-circuit line with a voltage of 110 kV.

Rice. 13. Portal intermediate reinforced concrete support with braces of the line with a voltage of 330 kV.

With a horizontal arrangement of wires on lines with a voltage of 330-500 kV, portal reinforced concrete intermediate supports on guys are used (Fig. 13). The supports are installed on reinforced concrete foundations with hinges at the support points of the racks. The foundations are embedded in the ground with such an inclination that the axes of the support posts and the axes of the foundations coincide. Guys are made of steel spiral rope. The lower ends of the guys are attached to the anchor plates embedded in the ground using special U-shaped anchor rods with threaded ends to control the tension.

Metal poles are used on lines with a voltage of 35 kV and above. These supports require a large amount of metal and regular painting during operation to protect against corrosion. They are made of steel 3 with additional guarantees of strength.

Metal poles are mainly used in mountainous areas and in other hard-to-reach areas, as they are transported in separate sections. Metal supports are installed on reinforced concrete foundations, which can be monolithic (solid), prefabricated and piled. Monolithic foundations are made at the place of installation of the support, while pile and prefabricated foundations are made at factories. With normal soil, i.e., in the absence of rocks, quicksand, swamps, etc., preference is given to piled reinforced concrete foundations, since their immersion in the ground is feasible in a mechanized way (for example, using vibrators).

On fig. 14 shows an anchor metal support with a wide base for a double-circuit line with a voltage of 110 kV, and in fig. 15 - angular anchor support for a 500 kV line.

Rice. 17. Intermediate metal supports of double-circuit lines: a - voltage 220 kV; b - 330 kV; (dimensions in meters).

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Types and types of supports for overhead power lines - School for an electrician: device, installation, adjustment, operation and repair of electrical equipment

Types and types of supports for overhead power lines

Depending on the method of suspension of wires, the supports of overhead lines (VL) are divided into two main groups:

a) intermediate supports. on which the wires are fixed in supporting clamps,

b) anchor type supports. wire tensioners. On these supports, the wires are fixed in tension clamps.

The distance between the supports of overhead power lines (TL) is called the span. and the distance of the maenad by anchor type supports - by the anchored section (Fig. 1).

In accordance with the requirements of the PUE, the intersection of some engineering structures, for example, public railways, must be carried out on anchor-type supports. At the corners of the line, corner supports are installed, on which the wires can be suspended in support or tension clamps. Thus, the two main groups of supports - intermediate and anchor - are divided into types that have a special purpose.

Rice. 1. Scheme of the anchored section of the overhead line

Intermediate straight supports are installed on straight sections of the line. On intermediate supports with suspension insulators, the wires are fixed in supporting garlands hanging vertically; on intermediate supports with pin insulators, the wires are fixed by wire knitting. In both cases, intermediate supports perceive horizontal loads from wind pressure on the wires and on the support, and vertical - from the weight of wires, insulators and the own weight of the support.

With unbroken wires and cables, intermediate supports, as a rule, do not perceive the horizontal load from the tension of wires and cables in the direction of the line and therefore can be made of a lighter design than other types of supports, for example, end supports that perceive the tension of wires and cables. However, to ensure reliable operation of the line, intermediate supports must withstand some loads in the direction of the line.

Intermediate corner supports are installed at the corners of the line with wires suspended in supporting garlands. In addition to the loads acting on the intermediate straight supports, the intermediate and anchor angle supports also perceive loads from the transverse components of the tension of the wires and cables.

At angles of rotation of the power line of more than 20 °, the weight of the intermediate corner supports increases significantly. Therefore, intermediate corner supports are used for angles up to 10 - 20°. At large angles of rotation, anchor angle supports are installed.

Rice. 2. Intermediate supports VL

Anchor supports. On lines with suspension insulators, the wires are fixed in the clamps of the tension garlands. These garlands are, as it were, a continuation of the wire and transfer its tension to the support. On lines with pin insulators, the wires are fixed on anchor supports with reinforced viscous or special clamps that ensure the transfer of the full tension of the wire to the support through the pin insulators.

When installing anchor supports on straight sections of the route and suspending wires on both sides of the support with the same tensions, the horizontal longitudinal loads from the wires are balanced and the anchor support works in the same way as the intermediate one, i.e. it perceives only horizontal transverse and vertical loads.

Rice. 3. Anchor-type overhead line supports

If necessary, the wires on one and the other side of the anchor support can be pulled with different tension, then the anchor support will perceive the difference in tension of the wires. In this case, in addition to horizontal transverse and vertical loads, the horizontal longitudinal load will also act on the support. When installing anchor supports at the corners (at the turning points of the line), the anchor corner supports also perceive the load from the transverse components of the tension of the wires and cables.

End supports are installed at the ends of the line. From these supports depart wires suspended on the portals of substations. When hanging wires on the line until the end of the construction of the substation, the end supports perceive the full one-sided tension of the wires and cables of the overhead line.

In addition to the listed types of supports, special supports are also used on the lines: transposition. serving to change the order of the wires on the supports, branch lines - to carry out branches from the main line, support for large crossings over rivers and water spaces, etc.

The main type of supports on overhead lines are intermediate ones, the number of which usually makes up 85-90% of the total number of supports.

According to the design, the supports can be divided into free-standing and guyed supports. Guys are usually made of steel cables. On overhead lines, wooden, steel and reinforced concrete supports are used. Designs of supports made of aluminum alloys have also been developed.

Structures of overhead lines

1. Wooden support LOP 6 kV (Fig. 4) - single-column, intermediate. It is made of pine, sometimes larch. The stepson is made of impregnated pine. For 35-110 kV lines, wooden U-shaped two-column supports are used. Additional elements of the support structure: hanging garland with a hanging clip, traverse, braces.
2. Reinforced concrete supports are made as single-column free-standing, without braces or with braces to the ground. The support consists of a post (trunk) made of centrifuged reinforced concrete, a traverse, a lightning protection cable with a ground electrode on each support (for lightning protection of the line). With the help of a grounding pin, the cable is connected to a grounding conductor (a conductor in the form of a pipe hammered into the ground next to the support). The cable serves to protect the lines from direct lightning strikes. Other elements: rack (trunk), traction, traverse, cable rack.
3. Metal (steel) supports (Fig. 5) are used at a voltage of 220 kV or more.

Rice. 4. Wooden single-column intermediate support of a 6 kV transmission line: 1 - supports, 2 - stepson, 3 - bandage, 4 - hook, 5 - pin insulators, 6 - wires

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types of transmission towers | electric-zone.com

Types of power line supports (by type of material).

According to the type of material, the following types of power transmission line supports are distinguished: reinforced concrete, wooden (impregnated) and metal supports.

Wooden supports in our time are outdated and are no longer used. Previously, they were used on overhead lines with voltage up to 220 kV inclusive. Such supports were usually made of pine and larch. The service life of pine poles is 5-7 years, and of larch 15-25 years. To increase the service life, wooden poles were impregnated with antiseptics that prevent decay. Depending on the concentration of the impregnating composition and the method of impregnation, the service life of pine poles increases to 15-25 years. For such supports, instead of wooden stepchildren, reinforced concrete ones were used. which further increases their service life. Example in Figure 1.

Figure 1. Wooden U-shaped intermediate support for a 110 kV single-circuit transmission line

Reinforced concrete supports are made from centrifuged reinforced concrete, while saving metal. The supports are cone-shaped with a slight slope of the generators. they are made in the factory on special machines. The length of the support post is 20-25 m. Such supports are used on lines with a voltage of 35 and 110 kV. They are installed by a crane into a cylindrical pit dug by a drilling machine. On lines with a voltage of 220 and 500 kV, U-shaped supports with guys are also used. Example in Figure 2.

Figure 2. Reinforced concrete U-shaped intermediate support for a single-circuit transmission line 220 kV.

Metal supports are made of steel grades St3, St5 and low-alloy steel. They are strong and reliable, but require a lot of metal. To protect against corrosion, metal supports are coated with oil paint. They are used on lines with a voltage of 110 kV and higher and are installed on metal steps or concrete foundations. Example in Figure 3.

Figure 3. Metal U-shaped intermediate support for single-circuit transmission line 110 kV

See also: Types of power line supports by purpose.

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1. The device of overhead power lines.

World experience and first steps

The first power transmission lines appeared at the end of the 19th century and structurally had much in common with telegraph and telephone lines. In most cases, it was permissible to use the same insulators, fasteners and poles as on communication lines. Since the distances between the supports were small, 50-70 meters, wooden poles with iron hooks or horizontal consoles - traverses were most often used. The choice between hooks and traverses was made depending on the number and section of the suspended wires, as well as the location of the line. The hooks were screwed into the post from two sides in a checkerboard pattern, and each of them had one insulator. On the traverses, as a rule, from two to eight insulators were placed in a row. In cases where increased mechanical strength was required, riveted metal masts, also equipped with hooks or traverses, were used as supports. With the introduction of three-phase AC networks of 2 and 6.6 kV, new types of supports began to appear, designed to suspend three ( fig.1) or six (for double-circuit lines) wires, however, the conditions for the construction of lines still made it possible to manage with the simplest designs and approaches. Often, the dimensions of the supports and the conditions for installing the wires were set by eye by an experienced fitter, and were not obtained as a result of the calculation. The first domestic supports for 6.6 kV lines were almost always wooden, hooks or metal ones were used to fasten the wires, less often wooden traverses, each of which had one wire.

The use of three-phase alternating current, the rapid development of the electrical industry and the increasing demand for electricity have contributed to the growth of voltages used in transmission lines, thereby making it possible to transmit large powers over long distances. Lines with a voltage of 30-60 kV began to be widely used. In addition, the concept of an economic span began to come into use - the most advantageous distance between supports in terms of line construction costs. In this regard, for the first time, significant interest arose in the issues of mechanical calculation of power transmission line supports and the creation of new specialized structures - their use made it possible to increase the span length and achieve significant savings in the context of the high cost of insulation and reinforcement.

With an increase in voltage, steel was increasingly preferred among materials for poles: it was far from always possible and profitable to use wooden structures (the problem was their low reliability and short service life: the experience of using antiseptics for impregnating power transmission line poles at the beginning of the 20th century was still small ). It should also be noted that porcelain pin insulators, used at the beginning of the 20th century on lines with a voltage of 30-60 kV, were bulky, expensive, complex structures in production, transportation and installation ( fig.3), so the designers tried to reduce the number of insulators on the line. Metal supports made it possible to build lines with longer spans, which, in particular, made it possible to use fewer insulators. On the rice. four as an example, a porcelain pin insulator from the company Locke applied on the 60 kV Zamora-Guanajuato line. The height of the insulator was about 30 cm, the diameter of the top skirt was 35 cm, and the weight was about 7 kg. The insulators were delivered to the line in the form of two halves, the final assembly took place in the field using Portland cement.

In 1904, one of the first lines in the world was built to supply mines in the Mexican state of Guanajuato, which used only metal poles ( fig.5). The length of the three-phase single-circuit line was 100 miles, and the voltage was 60 kV. American engineers took part in the construction of the line. Supports for the line were purchased from an American company Aeromotor Windmill manufacturer of windmills. Windmill masts were well suited for use as poles in terms of mechanical strength and economy, as they required only minimal changes in design associated with the installation of fittings for attaching wires. The mast of the Zamora-Guanajuato line was 40 feet (12 m) high and consisted of four corners measuring 3 x 3 x 3/16 inches, connected by braces and diaphragms from smaller corners. At the top of the mast was a metal yoke for two pin insulators and a 3 ½-inch pipe for attaching the top pin insulator. To confirm the reliability of the design at the factory Aeromotor Windmill experimental supports were tested. The support was fixed horizontally to the wall of the building and a platform with lead weights was suspended from the top. The top insulator tube began to deviate from the horizontal position at a load of 900 pounds (405 kg), while the deflection of the mast itself did not occur. At a load of 1234 lb (555 kg), the pipe deflection reached 6 inches, after the load was removed, the residual deflection was 1 inch. With a load of 1560 pounds (702 kg), the pipe continued to bend until the load was on the ground. For the entire length of the line, except for a short section at Guanajuato, where, due to the nature of the terrain, 60-foot supports and extended 400-meter spans had to be used, the span was 132 meters.

The use of metal poles on the Zamora-Guanajuato line aroused significant interest among electrical engineers. In 1904-06, several more lines were built in the USA with supports of a similar design, including those purchased from the company Aeromotor Windmill. Favorable experience with such structures has had a significant impact on the approach to designing towers for more powerful lines.

An important factor that contributed to the spread of metal supports was the invention of suspension insulators. By 1907-08, the problem of linear isolation was acute in the electrical industry. At voltages above 50 kV, pin insulators became too bulky, fragile and inconvenient to install, in addition, they did not differ in high operational reliability. At voltages above 80 kV, the use of pin insulators became completely impossible. Suspension insulators were much more advantageous in this regard, however, they required higher supports. In 1907, Edward Hewlett and Harold Buck invented the first industrial suspension insulator ( fig.6). In the same year, the first "cap and rod" suspension insulator designed by John Duncan (John Duncan, fig.9). Hewlett suspension insulators were first used in 1907 on a 100 kV line by an American company. Muskegon & Grand Rapids Power Co. The line was built using metal poles and was 35 miles long. Duncan's insulators, which had a more advanced design, were installed on several lines in 1908, in particular, on a 104 kV line owned by the company Stanislaus Electric Power (Fig. 8), however, they showed low reliability due to the poor quality of the cement that connected the fasteners to the porcelain insulating piece. Similar problems associated with the quality of the cement binder plagued the first insulators "with a cap and a rod" of the company Ohio Brass. However, the benefits of suspension insulators were clear. By 1910-11, suspension insulators continued to improve, they were already produced by a number of factories in the USA and Germany and were increasingly used ( fig.7) in both the US and Europe: Europe's first 100 kV transmission line Lauchammer(1910) was built using only suspension insulators and only metal supports ( fig.10).

In the context of the rapid development of electrical networks in the 1910s and 20s, two main approaches to the design of metal poles emerged: American and German.

At the beginning of the 20th century, the United States created many different types of supports, but, basically, the American approach consisted in the use of spatial structures with a wide base, made up of rods (corners) of relatively small (compared to European structures) sections. This approach originated from the experience of building lines on metal poles in 1904-06, which was discussed earlier. Racks of supports in plan - square or rectangular, in some cases - triangular. Each leg was placed on a separate foundation. The arrangement of wires could be either triangular ( fig.8,11) or vertical ( fig.12) and horizontal ( fig.13-14). In the 1920s and 30s, American-type poles were used with a span of up to 250 m. In domestic practice, American-type poles are also known as "wide base".

The German approach involved the use of narrow square posts with the base placed on one massive, compact foundation. Belts (vertical corners) were connected by a cross or triangular lattice ("snake"). In the 1920s and 30s, German-type poles, also called "narrow-base", were used with a span of up to 200 meters and became widespread in Europe, as they made it possible to reduce the cost of alienated land ( fig.15, fig.4).

In France, there was a kind of single-circuit narrow base supports with a horizontal and triangular arrangement of wires ( fig.16).

Types of supports depending on the purpose

The operating conditions of poles on high-voltage lines differ significantly depending on the location of the pole and the place where the line passes. By purpose, the poles are divided into several types.

Intermediate (fig.17-18) - a support that, in the mode of normal operation of the line, perceives only transverse wind loads and the weight of the wires, but not their tension (the force with which the wire is pulled). Wire fastenings on intermediate supports are made in such a way as to minimize damage to the support in the event of an accident (wire breakage).

anchor (fig.19-20) - a support on which the wires are always fixed rigidly - “anchored”, the anchor support perceives the longitudinal tension of the wires ( fig.21). They try to arrange anchor supports in such a way that in normal operation the tension of the wires on both sides of the support is the same. Anchor supports are installed when crossing engineering structures, natural obstacles and every 1-1.5 km (according to the standards of the 1920-30s for 30-115 kV lines) to divide the line into anchor sections. Terminal support - a kind of anchor, which in normal mode perceives one-sided or significantly uneven tension and is installed at the beginning and end of the line, as well as before large transitions through natural obstacles. (large rivers, reservoirs, gorges, etc.).

corner (fig.22) - a support that is installed in places where the line changes direction. In normal operation, the corner support perceives asymmetric loads from wires, the resultant of which is directed along the bisector of the angle of rotation; therefore, such supports are always strengthened in an appropriate way and have massive foundations. According to the method of fastening the wires, the corner supports are divided into anchor-angle and intermediate corner ones.

There are also special types of supports: transitional, transpositional, branching.

Power transmission towers

In the Russian Empire, the first 30 kV transmission lines began to be built by the Electric Transmission Society, whose plans included the deployment of a local high-voltage distribution network in the Bogorodsky district of the Moscow province to supply nearby private factories. From the very beginning, it was decided to use metal poles for all lines, but the first 30 kV Power Transmission - Zuyevo line had to be built on wooden poles for a number of reasons. Approximately a year later, in 1914, the second line was built - to the village of Bolshie Dvory, on which, like on all subsequent ones, only metal supports were used. A significant part of the Society's lines passed through private property, and a fee was charged for renting land for supports, which is why, when considering structures, it was decided to stop at German-type supports, which occupied a smaller area than American ones. . The supports were produced by the Gujon plant in Moscow (now Hammer and Sickle), delivered to the Bogorodsky district in disassembled form on platforms along the Nizhny Novgorod railway, and then transported along the highway on horseback. For 30 kV lines, double-circuit poles of the C-15 and D-15 brands 15 meters high were used ( fig.23-24). The C-15 support was used as an anchor and corner support, the D-15 was its lighter version, made of profiles of a smaller section, and was used as an intermediate and, sometimes, an anchor. The trunk of the supports consisted of two sections with a triangular lattice. Belts were made from corners with a shelf of 70 - 100 mm, braces and diaphragms - from corners with a shelf of 30 - 60 mm. In the lower part of the support, the braces were attached to the belts using scarves, and in the upper part they were overlapped. All connections, except for fastenings of traverses and sections (which are provided for detachable), are made with rivets, which is due to the cheapness of rivets compared to bolts and little experience in using welding. To strengthen the wires on the supports, three traverses of a flat design are mounted, made of two steel strips each, and equipped with lugs for hanging garlands of dish-shaped suspension insulators or pins for attaching pin insulators. Initially, pin insulators were used on all intermediate and some anchor supports of 30 kV lines, however, at the end of the 1920s they were replaced by garlands of disk insulators for greater reliability, while the middle traverses were lengthened with spacers from the corners ( fig.24).

In 1915, the Electric Transmission Society completed the construction of a 70 kV power transmission line to Moscow, which connected the Electric Transmission station with the Gujon plant and MOGES. For this transmission line, 18-meter supports of the A-18 brands were used (anchor, fig.25) and B-18 (interim). The same supports were also used on 30 kV lines as transitional and anchor supports where increased reliability was required. The trunk of each of the supports consisted of two detachable sections. In the B-18, the lattices of both sections were triangular, made similar to the supports C and D.

At the A-18 support, the lower section had a cross lattice, the sections were connected to each other by reinforced overlays. All permanent connections on supports A-18 and B-18, as well as on 15-meter ones, are made using rivets. Spatial structure traverses were made of angle profiles. At the ends of the traverses, lugs for hanging disc-shaped insulators were reinforced, and removable parts for hanging double-circuit garlands were provided. Most of the poles had a vertical wire arrangement, but some were made with a barrel wire arrangement. Both the 15-meter and 18-meter supports did not have special wire posts, but were equipped with clamps for attaching a lightning wire to the top of the trunk. This arrangement was due to the theory that existed in those years about the action of a protective cable, according to which the cable should be fastened as close as possible to the phase wires, which increased the total capacitance of the line and contributed to a decrease in the magnitude of the overvoltage during induced waves.

The designs of supports A, B, C, D turned out to be successful and continued to be used after the October Revolution with almost no changes. In the 1940s and 50s, during repairs, welded wire posts two meters high were sometimes built on the supports of this series already in operation ( fig.26). Some lines with supports A,B,C,D have survived and are still in operation.

Supports GOELRO

Since the GOELRO plan envisaged the construction of powerful district power plants, designed, in particular, to power important industrial facilities, one of its key elements was the construction of a network of main and distribution power transmission lines. At first, the already familiar 30-35 kV lines were mainly used in distribution networks, for main transmissions it was supposed to master a new voltage class - 115 kV. By 1918-20, international practice already had a fairly large experience in the construction and operation of such power lines. The leading positions in the construction of power transmission lines of 100 kV and above, as well as the production of fittings for them, were occupied by the USA and Germany. It was the German and American experience that domestic engineers were guided by when creating metal poles for power lines for GOELRO lines.

On lines with a voltage of 115 kV and above, American-type poles were preferred. Due to the heavy weight, metal supports for lines of this voltage are usually made detachable, that is, the support is fixed to the bearings of a pre-prepared foundation. American-type intermediate and anchor supports could be installed without concrete foundations, which was quite significant, since concreting foundations in the field in the 1920s was considered one of the most difficult aspects of line construction. In addition, unlike in Europe, there was no question of the cost of alienating land for supports.

Metal poles for GOELRO transmission lines were manufactured by various mechanical plants, the largest of them: Stalmost Leningrad plant, Hammer and Sickle and Parostroy in Moscow, Kramatorsk plant in Donbass.

A significant influence on the choice of supports, especially at first, was the lack of metal: they tried to use metal supports for the construction of only the most critical lines, or only as anchor or corner ones. It is important to note that in the future, despite the increase in steel production, on lines of all voltage classes, considerable attention was paid to the expansion of the use of wooden poles, as more economical in conditions of low prices for mast timber. The increase in the service life of wooden supports was achieved through the use of antiseptics, rail or concrete stepchildren. In the 1929-30s, a standard project already existed and was used, which included not only intermediate, but also anchor and corner wooden supports for 110 kV overhead lines. In the 1930s, wooden poles began to be used on 220 kV lines.

On the first 115 kV line in the USSR, Kashirskaya GRES - Moscow, due to a shortage of metal, only wooden supports had to be used. The Kashirskaya line of 1922 was single-circuit, intermediate and anchor supports are shown in the figures. 17 and 19 respectively. The supports of this line were not treated with antiseptics. The quality of construction was poor, and the line was constantly being repaired due to damage to the supports. In 1931, a new double-circuit line Kashira - Moscow was built parallel to the old one on metal supports.

Another 115 kV power line was supposed to connect the Volkhovskaya HPP with a step-down substation in Leningrad. Professor N. P. Vinogradov supervised the design of the line. Basically, the installation of the supports of this line was completed in 1924, and in 1926 its operation began. Intermediate supports to save metal were made of wood ( fig.28), taking into account the experience of the Kashirskaya line. As anchor, corner, transposition and transitional supports of the American type with a horizontal arrangement of wires were used ( fig.27), the design of which was similar to the poles of the lines of companies Westinghouse and Montana Power. All permanent connections were made using rivets. The Volkhov-Leningrad line was double-circuit, but each circuit was located on separate supports. Such a decision, as well as the choice of a horizontal arrangement of wires, is explained by considerations of reliability and ease of installation and safety of maintenance. Supports of the American type of the Volkhov line were widely used in the electrical networks of the Leningrad Region and existed in several modifications.

The approach used in the construction of the Volkhov-Leningrad line was also applied in the networks of Mosenergo. In the late 1920s and early 1930s, many of Mosenergo's secondary single-circuit 115 kV lines were built using metal poles only as anchor and corner poles. As an example, the Golutvin-Ozery and Kashira-Ryazan lines can be cited. The Mosenergo design bureau developed its own American-type supports, which were somewhat different from the Volkhov ones ( fig.29-30). The design was also based on the solutions applied on the lines of the company Westinghouse. There were three brands of metal poles of the American type PKB Mosenergo for lines with wooden intermediate poles: anchor AM-101, angular UM-101 and transposition TAM-101, as well as two modifications: AM-101 + 4 and UM-101 + 4 with four-meter stands heights to use as transitional. U-shaped wooden poles designed by Mosenergo design bureau, similar to the poles of the Kashirskaya and Volkhovskaya lines, were used as intermediate ones.

Shatura supports

An important moment in the history of domestic transmission lines was the construction in 1924-25 of the line ShGES - Moscow. It was the first 115 kV power transmission line in the USSR, on which double-circuit metal poles were used. Alexander Vasilievich Winter took part in the design of the supports, as well as engineers A. Gorev, G. Krasin, A. Chernyshev. The route of the Shatura-Moscow line passed not only through the Moscow region and suburbs, but also through the very center of Moscow: the line crossed the Okruzhnaya railway at the Ugreshskaya station and went to the Moscow River along Arbatetskaya street, from where it went along Krutitskaya, Krasnokholmskaya, Kotelnicheskaya and Moskvoretskaya embankments to Zaryadye, where the end support was located ( fig.31), from which the line crossed the Moscow River and entered the substation of the Raushskaya HPP.

For the urban section of the power transmission line, special narrow-base poles with foundations of a special design were designed ( fig.32), for the rest of the line, American-type poles were used ( pic.18,20,33).

To increase the mechanical reliability of the supports, the “reverse Christmas tree” design scheme was chosen, in which the traverses narrowed from the top to the bottom. Such a scheme was not optimal from an electrical point of view, but it made it possible to avoid damage to the supports and their traverses in the event of wire breaks and falls. To protect against lightning strikes, a ground wire was located above each circuit. Mountings for single-circuit and double-circuit garlands of insulators were provided on the anchor supports, trapezoidal platforms were fixed on the corner supports at the ends of the traverses for more convenient suspension of double-circuit garlands when the line turned at large angles. The height to the lower traverse on the anchor and corner supports of the American type was 11 m, on the intermediate ones - 12 m, the vertical distance between the traverses on all supports was 3.1 m. connected together already on the track, also by means of riveting.

Based on the experience of the Shaturskaya line in 1925, Mosenergo Design Bureau developed a standard design for American-type double-circuit towers for I-II climatic regions. The poles of this project were somewhat different from those installed on the Shaturskaya transmission line, but retained the general technical solutions and characteristic appearance, for which they received the name "Shatursky" or "Shatursky type poles". In the 1920s, Shatura-type poles were installed mainly on Mosenergo lines: Power transmission - Moscow, Kashira - Moscow ( fig.34), the second line Shatura - Moscow, lines of the Moscow electric ring 110 kV. And from the end of the 1920s, Shatura supports began to be widely used in other regions of the USSR.

The standard project included the following main brands of supports ( fig.35): AM-103 - anchor, which also allowed the line to be rotated at an angle of up to 5º, PM-103 - intermediate, UM-102 - angular for rotation at an angle of up to 60º, UM-103 - angular for rotation at an angle of up to 90º, TAM-103 - transposition. Compared with the supports of the Shaturskaya line of 1925, the base and the width of the trunk were reduced, smaller corner profiles were used for the belts. In addition to supports of normal height, there were also increased modifications: AM-103 + 4, AM-103 + 6.8, UM-102 + 6.8.

All supports were riveted structures. The supports were delivered to the track in the form of separate factory-assembled sections, which were connected in place with riveting, sometimes with bolts.

The foundations of the intermediate and anchor supports were made in the form of four thrust bearings made of metal profiles, fixed in the ground without the use of concrete when the line passed through normal soil, with a light concrete base when the support was installed on a shallow peat bog or on piles when installed on a deep swamp. The thrust bearings of the anchor supports were distinguished by their large size, and also by the fact that their design included a sheet of boiler iron, which improved the work of pulling out along the line. The foundations of the corner and end supports were always made of concrete.

In 1929-31, “lightning-resistant” supports of the Shatura type of the AM-103g, PM-103g, UM-102g, UM-103g, AM-103g + 4 brands appeared, distinguished by increased height cable racks ( fig.36). In addition, the project included German-type supports of the following brands: anchor AM-102 and intermediate PM-102 ( fig.37).

Due to the fact that in the 1930s the USSR was mastering the factory assembly of supports using welding, by 1933 welded modifications of Shatura-type supports appeared.

Shatura supports of the new series consisted of welded sections, manufactured at the factory and connected on the track with rivets or bolts. Welded supports had a technological division similar to riveted ones, which made it possible to use the same equipment and templates in the construction of lines and was convenient in terms of transportation. The use of welding reduced the cost of the Shatura design by saving metal and somewhat simplified the factory assembly, since there was no need to drill many holes for rivets. There was also no need for riveting in the field, since the finished sections were connected only with bolts. However, as in the case of riveted supports, where strict control over the quality of the riveting is required, the production of welded supports requires careful checking of the absence of structural distortions and welds for lack of penetration and cracks.

There were the following brands of welded supports of the Shatura type ( fig.38-40): AM-109g - anchor, UM-113g - angular for rotation up to 90º, PM-109g - intermediate, UM-111g - angular for rotation up to 35º, UM-112g - angular for rotation up to 60º. The UM-111g and UM-112g supports are similar in barrel design to the AM-109g, but differ in asymmetric traverses. All welded supports of the Shatura type were made "lightning resistant". Welded joints on the supports of this series in the upper part of the trunk were made using gussets, the braces and diaphragms of the lower part of the trunk and the traverse were overlap welded. Traverses and cable racks were bolted to the barrel. The upper and middle sections are one-piece structures, and the lower section consists of four parts connected by bolts. Trapezoidal platforms are fixed on the corner supports at the ends of the traverses for more convenient fastening of insulator strings. As in the case of riveted supports, there were increased modifications with stands 6.8 meters high of a similar design ( fig.40). Narrow-base variants of welded supports of the Shatura type were not produced. Welded Shatura supports continued to be installed on power lines under construction until the end of the 1950s.

During the GOELRO period, lines of distribution networks of lower voltage, 30-35 kV, were also actively built. On these lines, there was an even greater variety of pole designs than on overhead lines with voltages above 100 kV. Since the poles of 35 kV lines are much smaller and lighter than the poles of 115 kV lines, one-piece structures of the German type, which are convenient for transportation and installation, are most widely used. One-piece supports were installed either directly into the ground or on a concrete pad. The foundation pit could be covered with earth or poured with concrete. There were, however, other designs. For example, the poles of the 35 kV line of the Ivanovskaya CHPP-1 had a narrow shaft and a wide base, such an arrangement later became widely used and became known as “mixed”, since it combined the advantages of wide-base and narrow-base poles. It is also worth canceling the supports of the flat ("flexible") design of the Zemo-Avchalskaya line 35 kV of 1929 ( fig.41).

In the 1920s, Mosenergo networks continued to use the A-18, B-18, C-15 and D-15 poles designed before the October Revolution. On the other hand, in the same years, Design Bureau Mosenergo designed for 35 kV lines new German-type double-circuit towers of the following brands ( fig.42): H - intermediate, ON - anchor, NU - angular. In addition, there was a special single-chain NB support. The letter H literally meant "German type". Unlike supports A, B, C, D, on which the wires were arranged vertically or in a “barrel”, German-type supports were made according to the “reverse Christmas tree” scheme. It was not possible to install pin insulators. The design of the German-type supports was riveted, the support shaft consisted of two sections, the traverses were bolted to the shaft. The first German-type poles had a low location of the lightning protection cable, as on the poles of the Electric Transmission Company, but later on all newly installed and already operated poles were equipped with an increased cable resistance.

Due to the shortage of metal during the construction of 35 kV lines, preference was given to wooden poles. Only the most important lines were built entirely on metal supports, otherwise, metal supports were used as corner and anchor in especially critical places. There were a large number of designs of wooden poles for 35 kV lines: single-circuit "candle", "dovetail" ( fig.43), A-shaped support "azik", single-chain U-shaped supports. Supports "candle" and "azik" could be used with pin insulators. Double-circuit supports "azik" with pin insulators VEO-38 were used on the power line 33 kV AMO - Rublevskaya pumping station built in 1923. The U-shaped poles, which were similar in design to the wooden poles of a 110 kV transmission line, were most widely used.

Svir and DGES

The new powerful hydroelectric power plants being built according to the GOELRO plan were intended to supply electricity to large industrial areas: the factories of Leningrad and the industrial giants of Zaporozhye under construction. In order to distribute the power of the stations, consumers had to build large trunk lines and branched local power networks, while the already mastered voltage classes of 35 and 110-115 kV no longer provided the required throughput and could not become the basis of the planned power systems. In the second half of the 1920s, Soviet engineers had at their disposal some foreign experience in both the design and operation of lines with voltages above 150 kV. In the USA and European countries at that time there were lines operating at a voltage of 220 kV. The technical solutions developed for the first 154, 161 and 220 kV lines are based both on foreign experience and on our own, completely original solutions.

In 1927, construction began on the Nizhnesvirskaya hydroelectric power station in the Leningrad Region. To transfer the energy of the Svir River to Leningrad, it was necessary to build the longest and most powerful power transmission line in the USSR. Professor N. P. Vinogradov, who had previously developed the Volkhov-Leningrad power transmission project, supervised the creation of the line. When drawing up an estimate in 1927, two options were considered for the construction of the Svir-Leningrad power transmission line: the first option was a four-circuit line with a voltage of 130 kV, and the second was a two-circuit line of 220 kV. The cost of building the line according to the first option was less, but the second option made it possible to provide more power. As a result, the second option was chosen for execution. The transmission line passed through extremely wetlands, however, as a result of a thorough study of all possible options for the route, the most passable and shortest was chosen. The length of the route in its final version was 272 km, the line was capable of transmitting power up to 240 MW, which corresponded to the peak planned capacity of two stations of the Svir cascade. Two transmission circuits were made in the form of separate lines, which was done to increase the reliability of transmission and ensure the safety of personnel during repairs when one of the circuits is turned off. According to the results of the economic calculation, a span length of 300 m was chosen, the length of the anchor section was 3 km. For reasons of economy and ease of maintenance, a horizontal arrangement of wires was chosen. In the original version, each circuit was protected by one steel-aluminum ground wire.

The Svir-Leningrad line was the first power transmission line designed in the USSR with a voltage above 115 kV, work on the project began in 1926. Based on the chosen distance between the wires and the height of their suspension, the variant of the American type support was considered as the main one ( fig.43). But this option did not meet modern requirements for the design of truss structures. It was required that the ratio of the length of the rods that make up the structure to the minimum radius of gyration should not exceed: 120-140 for the main racks, 160-180 for secondary elements and 200 for auxiliary, non-force-bearing parts. When calculating the support on the basis of this condition, a large number of non-working and weakly working elements of considerable length were obtained in the structure, which during construction would lead to excessive consumption of metal. The designers of the support faced the case when it is not rational to adapt the old structures to the new conditions.

During the consideration of various options, an H-shaped structure was chosen with the smallest free length of the elements of the facade grille ( fig.44), which made it possible to significantly reduce the weight of the support compared to the original version. The weight of the intermediate support was 3.3 tons, the weight of the anchor - 4.3 tons. A weight reduction was achieved, compared with the original version, by 17% for the intermediate and by 12% for the anchor supports. The total metal savings for the two chains of the line amounted to 1120 tons. To confirm the calculations, check the manufacturing conditions and obtain the actual safety factors, two experimental supports were manufactured and tested ( fig.45), intermediate and anchor. Conducted full-scale tests confirmed compliance with the norms and requirements of the calculation.

Although during the construction of the Svir-Leningrad line it was already possible to make supports using welding, due to the special importance of the line and for reasons of reliability, all supports were made using rivets. As mentioned above, initially each circuit was protected by a single lightning wire, located on a small triangular post above one of the legs of the support, but in subsequent years the entire line was equipped with two lightning wires. To protect the poles in case of wire breaks throughout the entire length of the line, except for crossings through engineering structures, release clamps were used, although the design of the poles was designed for a full one-sided load in case of failure of the clamp.

The Svir-Leningrad transmission line survived the Great Patriotic War, most of its original supports have been preserved and continue to be used to this day.

Another major object of electric grid construction was the construction of the DneproGES. The energy system of the DGES was supposed to feed the Donbass region and large industrial enterprises of Zaporozhye, including the Dneprokombinat complex: Ferroalloy Plant, Metallurgical Plant and Aluminum Combine. The main lines of the power system operated at 161 and 150 kV, and the distribution networks also used 35 kV. In addition, there was a ring of 150 kV lines in Dnepropetrovsk, which ensured a more reliable operation of the power system. The longest line was the power transmission line 161 kV DGES - Rykovo (Donbass), the length of which was 210 km, and the total length of the lines, counting along one circuit, was approximately 900 km.

The design of power transmission lines for the energy system of the DGES was led by Professor N. P. Vinogradov.

The conditions for the mechanical calculation of the supports were very difficult due to the fact that the power lines of Dneprostroy passed through icy areas. Due to significant wind loads, causing a strong deviation of insulators and wires, the calculated distance between the wires reached 6.4 m, which, even taking into account the lower operating voltage, corresponded to the parameters of the Svir-Leningrad line. In this regard, and also for greater lightning resistance, it was decided to use a modified version of the "Svir" supports for the lines with a horizontal arrangement of wires. The lower voltage made it possible to reduce the height of the line, in connection with which the upper part of the supports was somewhat simplified, while the lower part remained unchanged.

The supports were designed for use with a normal span of 220 m and a steel-aluminum wire of the AC brand with a cross section of 120 mm 2. In some cases, the same supports were used with AC-150 wire, but with reduced spans. Intermediate weight ( fig.47) support was 3.28 t, anchor ( fig.46) - 4.6 tons. Each line was protected by two ground wires. To check the correctness of the choice of design, an American-type support project was made, the calculation showed that the use of Svir type supports saves 20% of metal savings. Supports of the Svir type were used on most lines of the Dneprostroy.

A different design of supports was used on very long, but less critical lines 161 kV DGES - Donbass and DGES - Dnepropetrovsk-Kamenskoye. When studying various options for double-circuit supports with a horizontal arrangement of wires for these lines, among others, a three-post support with a common traverse was considered, but all support options turned out to be too heavy. However, unexpected and favorable results were obtained when dividing a three-post double-chain support with a single crosshead into three separate supports, each of which carried two wires ( fig.48,50). This option provided significant savings in metal compared to the use of two single-column supports. The placement of mechanically unconnected posts on separate concrete blocks made it possible to avoid the problems inherent in wide-base supports with the appearance of stresses caused by foundation settlement. Three-post supports were more transportable, provided more favorable conditions for mounting wires and insulators. The disadvantages of the design were the volume of foundations, which was larger than when using two wide-base supports, and the possibility of failure of both chains at once if the middle support was damaged. Taking into account all factors, the use of a three-column design reduced the cost of line construction by 10% compared to the option of building a double-circuit line on single-column wide base supports.

After the three-post design was approved for use on the DGES - Donbass and DGES - Kamenskoye lines, two experimental supports were built: welded and riveted ( fig.49). In June 1930, both supports were successfully tested, and the welded support showed higher actual safety factors than the riveted one. Based on the tests, it was decided to use electric welding for the manufacture of intermediate supports. This was the first significant domestic experience in the use of welded supports on high-voltage lines. Anchor, corner and special supports were made riveted.

The adopted types of supports were used with release clamps for spans up to 235 m along the entire length of the line, except for especially icy areas. On the line DGES - Donbass, the SA-150 wire was used, in connection with which the structures of the anchor supports were strengthened.

To reduce the initial cost, the DGES - Donbass and DGES - Kamenskoye lines were built in two phases. As the hydroelectric power station reached its full capacity, first one circuit of each line was built, then the second was completed. At the same time, first of all, two two-wire lines were built, in which three wires were working, and the fourth remained a reserve until the construction of the third line and the commissioning of the second circuit.

In addition to conventional supports, unique transitional supports of various designs were created for the energy system of the Dnieper HPP, which deserve special mention.

After GOELRO

The first years of GOELRO, marked by the intensive construction of power lines of different voltage classes using a wide variety of technical solutions, were very important for gaining experience in the design and construction of high-voltage lines. In a very short time, new voltage classes were mastered: 110-115 and 220 kV. Already in 1931-32, the creation of power transmission lines with a voltage of 400 and 500 kV was discussed, various designs of supports were considered, attempts were made to extrapolate the experience of designing the Dneprostroy and Svir lines to new conditions. As for the existing stress classes, the improvement of the support structures for them continued. On the one hand, much attention was paid to the use of wood: in the late 1930s, wooden poles began to be used not only on 35 and 110 kV lines, but also on 220 kV power lines. On the other hand, the industrial giants of the first five-year plans came into operation, and the shortage of structural metal passed, which made it possible to use metal supports more widely. Some attention was paid to reinforced concrete supports, but at that time the technical difficulties associated with their production and installation still did not allow them to be widely used.

The general trend was the transition in the second half of the 1930s - early 1940s to the factory assembly of poles using electric welding: welded modifications of the Shatura type poles, which were mentioned above, welded poles for 35 and 220 kV lines appeared.

By the end of the 1930s, unified welded construction supports of the following grades were designed for 35 kV lines ( fig.51): A-37g - anchor, P-37g - intermediate and U-37g - angular. The supports were made according to the "Christmas tree" scheme. Traverses - channel, flat triangular design. Compared to the previous metal poles for 35 kV transmission lines, the length of the traverses and the vertical distance between them have been increased. The barrel consisted of two welded sections connected by bolts. Supports of this type were distinguished by a simple design and relatively low weight and were used everywhere until the end of the 1950s.

For 220 kV lines under active construction, by the mid-1930s, a standard design of single-circuit portal supports was created, which differed significantly from those used on the DGES and Svir-Leningrad lines. Portal-type supports consisted of two narrow posts of rectangular section, on which a horizontal traverse was placed ( fig.52). Each rack was strengthened on a separate compact foundation. The chosen design made it possible to make the supports more manufacturable, transportable and to reduce mechanical stresses arising from the settlement of the pillar foundations compared to the Svir-type wide-base supports. Portal support sections were fabricated at the factory using electric welding. On the track, finished sections were connected with rivets, and in later years with bolts. There were intermediate, anchor and corner versions of the support. Portal supports of this series were used everywhere on 220 kV lines and for a very long time - until the end of the 1950s. Among them: VL Stalinogorsk - Moscow, Rybinsk - Moscow and others. There were also typical transitional supports for 220 kV lines 35 and 70 meters high.

The departure from the use of structures of the GOELRO period began in the first post-war years. On the one hand, until the end of the 1950s, lines continued to be built on poles of the Shatursky type of welded structure and 220 kV lines on free-standing portals. On the other hand, narrow base supports and structures of the so-called "mixed" type were increasingly used. Mixed-type poles were used on 35-220 kV transmission lines and had the same trunk as the narrow-base ones (German type), and the lower section greatly expanding towards the foundation. Thus, mixed-type supports combined the advantages of narrow-base and wide-base ones. A significant variety of support designs appeared, created by various design institutes, the leader among which was the Leningrad Institute "Teploelektroproekt" (TEP). In addition, a greater number of options for supports have appeared, taking into account the characteristics of different climatic zones. In 1948, a new series of supports for 110 kV lines appeared, replacing the Shatura ones: supports of the "Crimean" type ( fig.53). According to the design of the trunk, these supports belonged to a mixed type. One of the variants of the intermediate support was narrow-base. In the manufacture of sections at the plant, electric welding was used, and bolts were used to connect the sections. The traverses were of a flat design, the bearing elements in them were channels. There were variants of supports for suspension of two and one ground wire. Supports of the Crimean type replaced the Shatura ones and became very widespread on the territory of the USSR, a significant number of such supports continue to be used. Welded supports of a mixed type (Crimean, Leningrad and others) continued to be used until the mid-1960s, as a result, they were replaced by more technologically advanced unified supports with bolted structures.

In addition, in the postwar years, the first 400 and 500 kV transmission lines were built in the USSR ( fig.55). They also reflected the experience gained during the formation of the power grid industry. Some general technical solutions used in the design of these lines were discussed as early as the early 1930s ( Fig.54).

Summing up the article, it is worth noting once again that the years of work of the Elektroperedachka society, and the first years of GOELRO, when the active construction of power lines was underway, and various approaches and technical solutions were being tested, were very important for the accumulation of invaluable experience in the design and construction of high-voltage lines, and also for the training of qualified engineering and technical personnel. The experience gained became the foundation for the entire subsequent development of domestic electrical networks and for the creation of a unified energy system.

Literature:

1. Engineer I.V. Linde, "Reference book for electrical engineers" 11th edition, second

state printing house, 1920

2. Koch, "High Voltage Power Transmission", Publishing House of the Bureau of Foreign Science and

Technicians, Berlin, 1921

3. A.A. Smurov, "High voltage electrical engineering and transmission of electrical energy",

printing house. Bukharin, Leningrad, 1925

4. W.E.K. high voltage bureau, Proceedings of the I All-Union Conference on the transmission of high power over long distances by ultrahigh voltage currents, GEI M-L, 1932

5. Technical Encyclopedia, chapters. ed. Martens, volume 20, OGIZ RSFSR, Moscow, 1933

6. Ing. V. V. Guldenbalk, Construction of high voltage power lines, ONTI NKTP USSR, GEI M-L, 1934

7. Electrotechnical Handbook (substations and high voltage networks) under general. ed.

engineer M.V. Khomyakova, GEI Moscow-Leningrad, 1942

8. Electrotechnical Handbook (high voltage electrical installations, substations, networks and power lines) under the general. ed. eng. M.V. Khomyakova, GEI Moscow-Leningrad, 1950

9. Power lines and substations 400 kV, ORGENERGOSTROY, Kuibyshev, 1958

E.V. Starostin, “Dreams and masts of the Shatura romantics”

Fig.43 - photo by Dmitry Novoklimov

The main elements of air lines. Supports.

supports

Supports are one of the main structural elements of power lines, responsible for the suspension of electrical wires at a certain level.

Support classification.

Supports can be classified according to various criteria: by purpose (by the nature of the perceived loads), by the features of their design, by the material from which the support is made, by the method of fixing in the ground, by the number of electrical energy transmission circuits, etc.

Depending on the purpose of the support, it must withstand certain loads. According to the nature of the perceived loads supports are divided into two types: those that perceive tension from wires and cables and those that do not perceive such tension. Depending on this, the following types of supports are used:

• Intermediate - installed on straight sections of the route, they perceive vertical forces from the weight of wires, insulators, fittings and horizontal loads from wind pressure on the support and wires. Intermediate supports can also be installed in places where the direction of the route changes at angles of rotation of less than 20-30 degrees, in which case they also perceive transverse loads from the tension of the wires. In emergency mode (when one or more wires are broken), the intermediate supports take the load from the tension of the remaining wires, are subjected to torsion and bending. Therefore, they are calculated with a certain margin of safety. Intermediate supports on the lines are 80-90%.
• Anchor - are installed in places where the direction of the route, the number, grades and cross-section of wires change, as well as at the intersection of overhead lines with various structures, perceive the tension forces of overhead lines.

a	b

Picture. Overhead line supports: a - intermediate support; b - anchor support.

On the basis of anchor supports can be performed:

• end supports - are installed at the beginning and end of the overhead line, they perceive unilateral tensile forces of the wires,
• corner supports - are installed in places where the direction of the route changes,
• branch supports - designed to carry out branches,
• cross supports - are installed at the intersection of overhead lines,
• transitional - are installed at the points of transition of the line route through various obstacles (railways and roads, rivers and reservoirs, etc.),
• transposition supports - designed to change the arrangement of phases on the support.

Picture. Anchor supports: a - angular; b - branch; c - transpositional.

In the GALLERY section there is a photo album "Classification of overhead line supports by purpose".

According to the material from which they are made, supports can be:

1. Low cost. Wooden poles are cheaper than reinforced concrete and metal poles;
2. A wooden pole is much lighter than a reinforced concrete pole (about 3 times), which reduces the cost of their transportation to the installation site, in addition, the installation of wooden poles does not require the use of heavy-duty crane mechanisms. If necessary, a wooden support can be installed in the ground manually;
3. Good dielectric properties, which leads to a decrease in leakage currents on overhead lines;
4. Wooden supports withstand bending loads better than reinforced concrete ones (about 1.5-2 times), so they better withstand ice and wind loads;
5. The likelihood of a "domino effect" is reduced. Since a reinforced concrete pole is much heavier than a wooden pole, falling it can drag adjacent poles along the entire anchor span, a lighter wooden pole will be held on tensioned wires, which reduces the number of emergency shutdowns on the lines;
6. "Conditionally" high service life. In accordance with GOST 20022.0-93, the average service life of wooden poles can reach 45-50 years.

Disadvantages of wooden supports:

Currently, wooden poles are used, as a rule, on overhead lines up to 1 kV.

Picture. Metal supports: a - lattice type; b - from multifaceted bent racks.

Polyhedral metal supports are made of racks in the form of hollow truncated pyramids made of steel sheet with a cross section in the form of a regular polyhedron. Rack sections are interconnected by telescopic or flange connections. The traverses of such supports are multifaceted, lattice or insulating.

Advantages of multifaceted transmission towers:

1. Less construction time. The timing of the construction of overhead lines on multifaceted supports is less than that of overhead lines made of reinforced concrete and metal lattice supports. This is due to a reduction in labor costs due to increased span distances, ease of installation of multifaceted supports, as well as a small number of assembly elements.
2. Lower shipping costs. Multifaceted poles are distinguished by low transportation costs: 1.5-2 times cheaper than lattice poles, and 3-4 times cheaper than reinforced concrete poles. The length of the sections is 12 m, which makes it possible to use standard overall vehicles for transportation. The telescopic design of the supports allows one section to be placed inside another during transportation.
3. Small land plot. When using multifaceted supports, the cost of permanent land acquisition is reduced. Compared to reinforced concrete supports, the gain is provided by a smaller number of supports with an equal outlet per one support, and compared to lattice ones, due to a smaller outlet under one support with an approximately equal number of supports.
4. Economic efficiency. Taking into account the above advantages, the use of multifaceted steel poles in the construction of high-voltage transmission lines allows you to save up to 10% of money compared to reinforced concrete and up to 40% compared to metal lattice poles.

Racks of reinforced concrete supports are made of concrete reinforced with metal.

Picture. Reinforced concrete structure.

The tensile strength of concrete is an order of magnitude lower than the compressive strength, therefore, to increase the tensile strength of the supports, steel reinforcement is embedded in the concrete. Approximately the same coefficients of thermal expansion of steel and concrete exclude the appearance of internal stresses in reinforced concrete during temperature changes.

At present, the share of overhead lines with reinforced concrete supports is about 80% of the length of all lines under construction.

The wide distribution of reinforced concrete poles of overhead lines is due to the relative cheapness of structures, the high level of unification and typification of poles, and the presence of a wide production base. Reinforced concrete supports have high mechanical strength, are durable (service life is about 40 years) and do not require high operating costs. Labor costs for their assembly are much lower than for the assembly of wooden and metal lattice-type supports. A positive quality of reinforced concrete is also reliable protection of metal reinforcement from corrosion. In order to protect the reinforcement from corrosion, the supports at the factory are covered with waterproofing - asphalt-bitumen varnish.

The disadvantage of reinforced concrete supports is their large mass, which increases the cost of transportation and necessitates the use of heavy-duty cranes during assembly and installation. Reinforced concrete supports of overhead lines are able to withstand 2-3 times less emergency loads than metal ones, and twice as many supports are required for the construction of lines. In addition, when stretched, steel can elongate 5-6 times more than concrete, as a result of which cracks can appear in concrete. To increase the crack resistance of reinforced concrete structures, prestressing of the reinforcement is used, which creates additional compression of the concrete.

Reinforced concrete racks of an annular section (conical and cylindrical) are made on special centrifugal machines (centrifuges) that form and compact concrete by rotating the mold around its axis. Racks of rectangular section are made by vibrating, in which the compaction of concrete in molds is carried out by vibrators. For power lines with a voltage of 110 kV and above, only centrifuged racks are used, and for overhead lines up to 35 kV - both centrifuged and vibrated.

Picture. Reinforced concrete racks of overhead line supports: a - rectangular section; b - annular section.

Traverses of reinforced concrete supports are made of metal. Work is also underway to create fiberglass traverses, in which the concrete is reinforced with fiberglass. Separate sections of overhead lines with such traverses and supports are in pilot operation.

According to the method of fixing in the ground:

By number of chains:

Overhead line supports are also distinguished by design, which depends on the purpose of the overhead line, its voltage, the number of wires and cables suspended on the support, their location, climatic and other conditions. The simplest support design is a single pole ("candle"). In addition to the “candle”, more complex supports are used: A-shaped, tripods, U-shaped (portal), AP-shaped, etc.

Picture. Supports of overhead lines: a - V-shaped support (type "nabla"); b - Y-shaped support; c - tripod-type support.

In the GALLERY section there is a photo album "Classification of overhead line supports by design".

In addition to the typical designs of overhead line supports, in practice you can also find unique supports.

In the GALLERY section there is a photo album "Unique overhead line pylons".

By installation method:

Electricity is the main form of energy in use today. Its widespread use became possible thanks to electric networks, which combine sources and consumers of electricity. Power lines, or power lines for short, perform the function of transporting electricity. They are laid either above the surface of the earth and are called "air", or buried in the ground and or under water and are called "cable".

Overhead power lines, despite their complex infrastructure, are cheaper than cable lines. By itself, a high-voltage cable is an expensive and complex product. For this reason, these cables are laid only in some sections along the route of the overhead power line in those places where it is impossible to install supports with wires, for example, through sea straits, wide rivers, etc. Cables are used to lay electrical networks in settlements, where the construction of supports is also impossible due to urban infrastructure.

Power lines, despite their great length, are still the same electrical circuits for which Ohm's law is applicable in the same way as for the rest. Therefore, the efficiency of power transmission lines is directly related to the increase in voltage in it. The current strength decreases, and with it, the losses become smaller. For this reason, the farther from the power plant consumers are located, the more high-voltage power lines should be. Modern ultra-long power transmission lines transmit electrical energy with voltages of millions of volts.

But increasing the voltage to reduce losses has limitations. Their cause is corona discharge. This phenomenon manifests itself, causing a noticeable loss of energy, starting with voltages above 100 kilovolts. The buzzing and crackling of high-voltage wires is a consequence of a corona discharge on them. For this reason, in order to reduce corona discharge losses, starting from 220 kilovolts, two or more wires are used for each phase of an overhead power line.

The length of power lines and their operating voltage are interconnected.

• With voltages from 500 kilovolts, ultra-long power lines operate.
• 220 and 330 kilovolts are voltages for main power lines.
• 150, 110, and 35 kilovolts are the voltages of distribution power lines.
• Voltages of 20 kilovolts or less are typical for local power networks, which supply electricity to end consumers.

Supports for wires

In addition to wires, power transmission lines include supports as the main structural elements. Their purpose is to hold wires. Each power line has several types of supports, as shown in the image below:

Anchor supports take heavy loads and therefore have a strong rigid structure, which can be very diverse. All supports are in contact with weak or wet ground through a concrete foundation. Wells are made in solid soil, into which power transmission towers are directly immersed. Examples of designs of metal anchor supports are shown in the image below:

Supports can also be made using concrete or wood. Wooden supports, although less durable, are one and a half times cheaper than metal and concrete structures. Their use is especially justified in regions with severe frosts and large stocks of timber. Wooden poles are most widely used in electrical networks with voltages up to 1000 volts. The design of such supports is shown in the image below:

Power line wires

The wires of modern power lines are mainly made of aluminum wire. Pure aluminum wires are used for local power lines. The limitation is the span between the supports of 100 - 120 meters. For longer spans, aluminum and steel wires are used. Such a wire has a steel cable inside, covered with aluminum conductors. The cable perceives mechanical load, aluminum - electrical.

All-steel wires are used only in non-stretched areas where maximum strength with minimum wire weight is required. All power lines with voltages above 35 kilovolts are equipped with a steel cable to protect against lightning strikes. Wires made of copper and bronze are currently used only in power lines for special purposes. Copper and aluminum wire is used to make hollow tubular wires. This is done to reduce losses in the corona discharge and to reduce radio interference. Images of wires of various designs are shown below:

The wire for power lines is selected taking into account the working conditions and the resulting mechanical loads. In the warm season, it is the wind that shakes the wires and increases the load on the gap. In winter, ice is added to the wind. The layer of ice on the wires with its weight significantly increases the load on them. Moreover, a decrease in temperature leads to a decrease in the length of the wires and increases the internal stress in their material.

Insulators and fittings

Insulators are used to securely connect wires to poles. The material for them is either electrical porcelain, or tempered glass, or polymer, as shown in the image below:

Glass insulators under the same conditions are smaller and lighter than porcelain ones. Structurally, insulators are divided into pin and suspension. The pin design for power lines with voltages above 35 kilovolts is not used. The mechanical loads taken by suspension insulators are greater than those of pin insulators. For this reason, the suspension structure can also be used at lower voltages instead of pin insulators.

The suspension insulator consists of individual cups connected in a garland. The number of cups depends on the voltage of the power line. To connect the cups into a garland and all other wire and insulator fasteners, special fittings are used. Reliability, strength and durability in an open environment are determined by such materials for the manufacture of fittings as steel and cast iron. If it is necessary to obtain increased resistance to corrosion, parts are coated with zinc.

Fittings include various clamps, spacers, vibration dampers, coupling connectors, intermediate links of insulators, rocker arms. A general idea of ​​\u200b\u200bthe reinforcement gives the image below:

Protective devices

Another component of the device of power lines are structures that protect equipment connected to power lines from atmospheric and switching overvoltages. From lightning strikes, protection is provided by a cable stretched above all the wires of the power line and lightning rods, which are usually installed near substations. Protective gaps are located on power line supports. An example of such a gap is shown in the image on the left. Tubular arresters are installed near substations, in which there is a spark gap inside. If it breaks through and at the same time an arc is formed, fed by a short circuit current, a gas is released that extinguishes this arc.

All technical and organizational nuances for the arrangement of power lines are regulated by the Electrical Installation Rules (PUE). Any deviations from these rules are strictly prohibited and can be considered as a crime of one or another gravity, depending on the consequences thereof.

When laying overhead power lines, in addition to choosing a cable, it is also necessary to select the supports on which it will be fixed, as well as insulators. We will devote this article to the supports of overhead power lines.

For the construction of overhead lines, metal, reinforced concrete and wooden, as they are often called in everyday life, electrical poles are used.

wooden supports

They are made, as a rule, from pine logs with the bark removed. For power lines with a supply voltage of up to 1000 V, other tree species are also allowed, for example, fir, oak, cedar, spruce, larch. Logs, which will subsequently have to become the supports of power lines, must meet certain technical requirements. The natural taper of the trunk, in other words, the change in its diameter from the thick lower end (butt) to the upper cut should not exceed 8 mm per 1 meter of log length. The diameter of the log on the upper cut for lines with voltage up to 1000 V is taken to be at least 12 cm, for lines with voltage above 1000 V, but not more than 35 kV - 16 cm, and for lines with higher voltage - at least 18 cm.

Wooden poles can be used for the construction of overhead lines with a voltage not exceeding 110 kV inclusive. Wooden poles are most widely used in overhead lines with voltage up to 1000 V, as well as in communication lines. The advantage of wooden poles is their relatively low cost and ease of manufacture. However, there is a minus, a significant minus - they are subject to decay and the service life of pine supports is about 4-5 years. To protect the wood from decay, it is impregnated with special antiseptics against decay, such as anthracene or creosote oil. Especially careful processing lends itself to those parts that will be dug into the ground, as well as cutting ends, braces and traverses. Thanks to antiseptics, the service life is increased by about 2-3 times. For the same purpose, quite often the legs of a wooden electric pole are made of two parts - the main stand and the chair (stepson):

Where - 1) the main stand, and 2) a chair (stepson)

With a strong decay of the lower part, it is enough to change only the stepson.

Metal supports

Plus - durable and reliable in operation. Minus - a large consumption of metal is required, which entails a significant increase in cost (in comparison with wooden ones). Metal poles of overhead power lines are used, as a rule, at voltages from 110 kV, since the operation of metal poles is caused by high costs for very labor-intensive and expensive work on periodic painting that protects against corrosion.

Reinforced concrete supports

In the industrial manufacturing process, they are the best option for overhead lines both up to 1000 V and above 1000 V. The use of reinforced concrete supports dramatically reduces operating costs, since they practically do not require repair. At present, almost everywhere, in the construction of overhead lines of 6-10 kV and up to 110 kV, reinforced concrete supports are used. They are especially widespread in urban networks up to and above 1000 V. Reinforced concrete supports can be made both monolithic (cast) and in the form of assemblies that are assembled directly at the installation site. Their strength depends on the method of concrete compaction, of which there are two - centrifugation and vibration. When using the centrifugation method, a good concrete density is obtained, which subsequently has a good effect on the finished product.

On overhead power lines, special, anchor, corner, end, intermediate supports are used.

Their purpose is to rigidly fasten wires and lines to them. Places for their installation are determined by the project. By design, the anchor support must be strong, since if the wire breaks on one side, it must withstand the mechanical load of the wires on the other side of the line.

Anchor spans are the distance between anchor supports. On straight sections (depending on the cross section of the wires), anchor spans have a length of up to 10 km.

intermediate supports

They serve only to support wires on straight sections of the line between the anchor supports. Of the total number of electrical poles installed on the line, intermediate ones occupy about 80-90%.

Angle supports

Are intended for installation in places of turn of a route of a power line. If the angle of rotation of the line is up to 20 0, then the electric pole can be made as an intermediate one, and if the angle is about 20-90 0, then as an anchor.

They have an anchor type and are installed at the beginning and at the end of the lines. If in anchor electric supports the force of one-sided tension of wires can occur only in an emergency, when the wire breaks, then in end electric supports it always acts.

Special supports

They are electric poles of increased height and are used at the intersection of power lines of power transmission lines with highways and railways, rivers, at the intersection between the power lines themselves and in other cases when the standard height of the electrical pole is not enough to provide the required distance to the wires. Intermediate electrical supports of lines with voltage up to 10 kV are single-column (candle-shaped). In low-voltage networks, single-column supports perform the functions of corner or end supports, and are additionally equipped with guy wires attached to the side opposite to the wire tension, or with struts (supports) that are installed from the wire tension side:

For lines with a voltage of 6-10 kV, electrical poles are A-shaped:

Air lines and main dimensions and dimensions are also characterized.

Overhead line gauge - the vertical distance from the lowest point of the wire to land or water.

The sag is the distance between an imaginary straight line between the wire attachment points on the support and the lowest point of the wire in the span:

All dimensions of power lines are strictly regulated by the PUE and directly depend on the magnitude of the supply voltage, as well as the terrain along which the route passes.

The PUE also regulates other dimensions when crossing and approaching power lines, both among themselves and between communication lines, highways and railways, air pipelines, cable cars.

To check the designed power transmission line with the requirements of the PUE, calculations are made for mechanical strength, the methods of which are given in special courses of electrical networks.