Overhead power line supports. Their structure and main types. Types of overhead power lines New transmission line supports

Depending on the method of hanging wires, overhead line (OHL) supports are divided into two main groups:

• intermediate supports on which the wires are fixed in supporting clamps,
• anchor-type supports used for tensioning wires. On these supports, the wires are secured in tension clamps.

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

In accordance with the requirements of the PUE, intersections of some engineering structures, for example public railways, must be carried out on anchor-type supports. At the angles of rotation 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.

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

With unbroken wires and cables, intermediate supports, as a rule, do not take up the horizontal load from the tension of the wires and cables in the direction of the line and therefore can be made of a lighter structure than supports of other types, for example, end supports that take the tension of the 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 angles of rotation of the line with wires suspended in supporting garlands. In addition to the loads acting on intermediate straight supports, intermediate and anchor corner supports also absorb loads from the transverse components of the tension of wires and cables.

At transmission line rotation angles 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 rotation angles, anchor corner supports are installed.

Anchor supports. On lines with suspended insulators, the wires are secured in the clamps of tension garlands. These garlands are like a continuation of the wire and transfer its tension to the support. On lines with pin insulators, the wires are secured to anchor supports with reinforced ties 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 equal tensions, the horizontal longitudinal loads from the wires are balanced and the anchor support works in the same way as an intermediate one, i.e., it perceives only horizontal transverse and vertical loads.

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 support will also be affected by horizontal longitudinal load. When installing anchor supports at corners (at the turning points of the line), the anchor corner supports also take the load from the transverse components of the tension of wires and cables.

End supports are installed at the ends of the line. Wires extend from these supports and are suspended on substation portals. When hanging wires on the line before the completion of the substation construction, the end supports absorb 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 lines: transpositional, used to change the order of arrangement of wires on the supports, branch ones - to make branches from the main line, supports for large crossings across rivers and water spaces, etc.

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

Based on their design, supports can be divided into free-standing and guyed supports. Guys are usually made of steel cables. Wooden, steel and reinforced concrete supports are used on overhead lines. Support designs made of aluminum alloys have also been developed.

General information about power line supports

Power transmission line supports are structures that serve to support live wires and lightning protection cables above the earth's surface. They come in various shapes and sizes. The supports can be reinforced concrete, wood, metal or even composite materials. The main elements of power transmission line support are racks, foundations, traverses (crossbars on which the wires are held), cable stands and guy wires are also often used.

ANCHOR SUPPORTS FOR POWER LINES
There are anchor and intermediate supports for power lines. The robust design of the anchor supports can withstand significant forces from wire tension; anchor supports of power lines are installed at the beginning and end of power lines, at turns, when power lines cross small rivers, railways, roads and bridges.
A type of anchor supports - transition supports are used when crossing power lines of rivers and other large obstacles. It is the transition supports that bear the heaviest loads and can themselves reach a height of 300 meters! These poles are the heaviest and tallest of all power line poles; they are often painted in bright colors, for example, red and white poles are often found, and orange, gray and other colors are also used. For more details about transition supports, see the corresponding essay http://io.ua/s73072.

INTERMEDIATE POWER LINE SUPPORTS
Intermediate supports have a less durable structure than anchor ones; they usually serve to support wires and cables on straight sections of power line routes. Most of the supports on the routes are intermediate. As a rule, an intermediate support can be distinguished from an anchor one by the following feature: if the garlands of insulators hang perpendicular to the earth’s surface, then the support is intermediate. And on the anchor supports, the wires are fixed in the clamps of tension garlands; these garlands are like a continuation of the line and are located at an acute angle to the surface of the earth, and sometimes almost parallel.
Also, power line supports are divided into:
- transposition (to change the order of phases),
- branch,
- cross,
- increased, decreased, etc.
Based on the number of suspended wires (circuits), supports are divided into single- and multi-circuit; by design - single-post, A- and AP-shaped, U-shaped, V-shaped (for example, “Nabla” type), “shot glass” type, etc.

WOODEN POWER SUPPORTS
Today, mainly reinforced concrete and metal power line supports are used. Wooden transmission line supports were installed on power lines with voltages up to 220 kV. Power line supports were usually made from pine and larch poles impregnated with an anti-rotten compound (antiseptic). Often wooden supports were strengthened on reinforced concrete attachments (stepchildren) or piles. Wooden power line supports were cheap, relatively easy to manufacture and reliable in operation. The first large Soviet power transmission line - Kashirskaya State District Power Plant - Moscow - with a voltage of 110 kV and a length of 120 km was built on wooden supports. Today, power lines with wooden poles are no longer built.

REINFORCED CONCRETE POWER LINE SUPPORTS
Reinforced concrete power transmission line supports, the designs of which were developed in the USSR in 1933, have higher mechanical strength. However, due to the lack of an industrial base, their mass use in the construction of power lines of all voltages began only in 1955. The advantages of reinforced concrete transmission line supports are simplicity of design and manufacturability of factory production. These power transmission towers are usually of a circular or rectangular cross-section and are made primarily of prestressed reinforced concrete.
The most common are intermediate single-post reinforced concrete power line supports with metal crossarms, which are installed directly in the ground. In addition, on power lines with a voltage of 110-500 kV, intermediate and anchor-corner reinforced concrete transmission line supports with guy wires were widely used.

METAL POWER LINE SUPPORTS
Metal transmission line supports have less weight than reinforced concrete ones and high mechanical strength. This allows you to create supports of considerable height, designed for heavy loads. They are used on power lines of all voltages, often in combination with reinforced concrete intermediate supports. Metal transmission line supports are indispensable on lines with heavy loads (for example, on crossings).
Metal power transmission line supports are made mainly of steel, and in some cases of aluminum alloys. According to the manufacturing method, metal transmission line supports are divided into welded ones, which come from factories in the form of finished sections, and bolted ones, which are assembled on the route from individual elements (braces, rods, chords) on bolts.
Metal supports are divided into two broad groups - lattice and MGS (multifaceted bent racks). If the first ones are well known to everyone, then IGUs are just beginning to become widespread in the CIS countries. A lot of useful information about these supports can be found on the website www.energobud.com.ua
By voltage, power lines within the CIS are divided into 35 kV, 110 kV, 154 kV (150 kV), 220 kV, 330 kV, 400 kV, 500 kV, 750 kV, 800 kV, 1150 kV and 1500 kV. Most of all power lines in the world operate on alternating current, but there are also lines that operate on direct current, for example, the Volgograd-Donbass DC power line (you can read about these power lines here http://io.ua/s91331).

POWER LINE VOLTAGE CLASSES
It can be difficult for a non-specialist to accurately determine the voltage in a power line, but, as a rule, this can be done in a simple way - counting how many insulators in a garland are suspended on a crossarm. So 35 kV power lines have three to five insulators in each garland. But in the garlands of 110 kV power lines there are already six to ten insulators. If there are ten to fifteen insulators, then it is a 220 kV power line.
If the power line wires are split into two (this is called splitting), then the line can have a voltage of 330 kV. If there are three wires in each phase, then 500 kV, if there are four wires, then 750 kV.
There are exceptions to every rule. Thus, 220 kV and 150 kV lines have splitting, although this is typical for 330 kV lines. 330 kV power lines, in special cases, can operate without splitting.
35 kV -110 kV power lines are used everywhere as distribution networks (for example, a 110 kV power line can supply a substation that powers a small village or microdistrict). The 150 kV class is a more advanced analogue of the hundred-tens; this voltage is used in the Dneproenergo power system and some adjacent areas, as well as in the Kola power system (Kola Peninsula). This voltage class came to the USSR in the early 30s, along with the American equipment of the General Electric company for the Dnieper Hydroelectric Power Station.
220 kV power lines are mainly used to connect power plants with substations and large consumers. 330 kV lines are often built over long distances, for communication between powerful power plants and substations (interconnections), and sometimes for the needs of very energy-intensive enterprises. Lines with voltages of 400 kV, 500 kV, and 750 kV and higher are also used for intersystem connections and for transmitting electricity over long distances, including to neighboring countries.

UNIFICATION OF POWER LINE SUPPORTS IN THE USSR
In 1976, in connection with the unification of power transmission line supports in the USSR, the following system for designating metal and reinforced concrete supports of 35-330 kV was adopted:
the letters P and PS indicate intermediate supports,
PVS—intermediate with internal connections,
PU or PUS - intermediate corner,
PP - intermediate transitional,
AN US - anchor-corner,
K or KS - end ones.
The letter B indicates reinforced concrete supports, and its absence indicates that the supports are steel. The numbers 35, 110, 150, 220, etc., following the letters indicate the line voltage, and the numbers behind them indicate the standard size of the supports. The letters U and T are added respectively to the designation of intermediate supports used as corner supports and with cable support. And in modern power grid construction, “de-unification” is observed, new original supports are being developed, designed for the conditions of a specific power line route. Thus, in developed countries they have already abandoned the mass use of standard projects. Each line must be built taking into account all the nuances of the relief, climate, etc.

CLASSIFICATION OF POWER LINE SUPPORTS BY GENERAL APPEARANCE

Tower supports
Classic, the most common of all high voltage power line supports. They can have from one to 9 parallel traverses, and are used for single-, double- or multi-circuit power lines. All lattice tower supports have a common feature - their trunk narrows from the base to the top. Divided into two families:
- wide-barreled lattice (if the base of the mast is wider than a freight car, see photo 1). These are the most common supports. They can be single-chain (“Crimean type”), double-chain (“barrel” type) and multi-chain.
The most interesting representatives of single-circuit tower supports are T-shaped supports for DC lines.
- narrow-base lattice (accordingly, their base is somewhat narrower in size than the base of a freight car).

Portal supports
Supports made of metal, wood or reinforced concrete, resembling the letter “P” or the letter “N”. They are widely used on 330-750 kV power lines. As a rule, single-chain.

AP-shaped supports
Single-circuit supports created using welded metal pipes, MGS or wood, resembling the letter “A” in profile and the letter “P” in front. The cross-section of pipes in these supports can reach 1300 mm, and the height can be over 80 m.
Photo 4 shows an example of such a tubular support when crossing a 330 kV line across the Dnieper, in Ukraine. Inside its racks there are stairs for climbing to the top, and in total the support has four legs, each 21 meters high (they are painted in different colors), the total height of the mast is about 85 meters. You can read more here - http://io.ua/s93360.

Three-post freestanding lattice supports
Three-post lattice supports, as a rule, stand at turns and transitions of 500 kV and 750 kV power lines and are used as anchors (photo 5).

L-shaped supports
They are flat L-shaped lattice structures, articulated with two foundations. At the top of the support there is a traverse for attaching 4 load-bearing cables that hold the support in a vertical position. Below there are three more (rarely two) traverses for hanging wires. L-shaped towers were used, in particular, as transition towers for two 110 kV or 220 kV overhead line circuits. Their use allowed us to save metal and simplify the foundation. It was advisable to use such supports in areas flooded with water during floods. Design features prevented these supports from becoming widespread.

Y-shaped supports, "shot glasses"
Single-chain masts resembling the letter “Y” or a glass (photo 6). There are different types and have been used for quite a long time both here and abroad, including as transitional ones (for example, PS-101). These supports are always made of metal, usually lattice, less often they consist of multifaceted bent posts.

V-shaped,"Nabla"
Intermediate pores with guys are used on power transmission line routes of 330-1150 kV, for example, Nabla type supports for 750 kV. They resemble an inverted triangle - nabla. Exclusively single-chain.

Class: "Cat" type supports
Very interesting original supports are very popular in Western Europe, especially in France (photo 10).

Pillar supports(i.e. not lattice)
These are supports based on wooden, metal or reinforced concrete pillars. There are single-post and portal ones. Single-post reinforced concrete supports are the most widely used intermediate power transmission line supports at voltages of 35-220 kV. Relatively recently, a progressive type of metal single-column pole supports has become widespread - using MGS. To be more precise, in the USA such supports have been used for quite a long time, but in the CIS they are just beginning to gain popularity. The use of MGS made it possible to create multi-chain pillar supports (see photo 8).
Portal pillar supports consist of two pillars (wooden, reinforced concrete or MGS) connected by a common crossbeam. Particularly widespread in our country are pole-mounted single-circuit portal reinforced concrete supports (with internal connections) for 220 and 330 kV lines (photo 9).

Non-standard supports
These include various non-standard supports and exotic ones that do not belong to this classification, for example, numerous decorative supports.

2011 "POWERLINER"

Updated 20 Jan 2016. Created 30 Nov 2010

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

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

In view of this, various designs are being developed to reduce the load on the foundation and ensure stable operation in various operating modes.

On our website you can familiarize yourself with both old and new developments of Russian engineers.

Classification by purpose

Each brand of support is designed to perform a specific function. That is why structures are divided into main types depending on their purpose:

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

Classification by materials of manufacture

The structures are installed in various climatic and geoseismic conditions. It is worth noting that many types of supports are designed for use in urban areas. Thus, in each case it is necessary to use suitable material for the manufacture of racks.

Wooden supports

Wooden power transmission line supports are widespread in rural areas, but do not forget that the corresponding wooden structures are also used on lines up to 220 kV.

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

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

Reinforced concrete supports

Reinforced concrete supports are installed on lines with voltages less than 500 kV. Basically, these are intermediate supports that do not take the load from the tension of wires and cables. If reinforced concrete racks are used as anchor supports, they are strengthened with bevels or braces.

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

1. simple design features;
2. do not require complex additional assembly;
3. are not subject to rotting like wooden supports;
4. in some cases it is possible to install directly into the ground;
5. relatively simple construction of the line.

Steel supports

Steel supports on 0.4-10 kV lines are installed extremely rarely. Their prerogative is medium voltage lines and higher. Metal supports are mainly used as anchor supports, however, when the network voltage is more than 110 kV, intermediate steel supports are also used.

The structures can be made either from profiles and corners, or by rolling, since metal supports based on pipes are often used in lighting. Among the advantages of supports of this type are their wear resistance and durability, as well as the ability to manufacture very high structures to ensure safe passage through engineering structures and natural barriers.

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

What associations arise when mentioning overhead power lines? Of course, the wires are stretched through the air from support to support or from pillar to post. Moreover, visually, the greater the span between the supports, the higher the wires are stretched, therefore, the higher the support itself should be. In fact, there is no direct relationship between the height of the support and the length of the span.

The basis for designing power lines is the voltage of the overhead line and its power. Based on them, the cross-section and type of wire (cable) are calculated, the weight of the cable is determined from the cross-section, the lengths of anchor and intermediate spans, as well as the types and sizes of supports are calculated from the weight. Also, the type of support depends on the number of “threads” of wires that are planned for the power line section, what branches will have to be made, etc.

Types of transmission line supports

In the process of development of power transmission lines, four types of supports have been established based on the material from which they are made:

• Wooden supports;
• Reinforced concrete supports;
• Metal supports;
• Prefabricated supports.

First things first.

Wooden power transmission poles

The wooden support is historically the oldest of all types of supports. By design, a wooden support is a pole made of coniferous timber, using the rounding method, 8.5 - 13 meters long. Also, parts for wooden supports are made from wood: traverses (a wooden horizontal beam on a support), struts (attaching a traverse to a support), crossbars (a crossbar on the edge of a support and a strut dug into the ground).

Advantages of wooden supports

Wooden supports, like any building material, have their advantages and disadvantages. The advantages of wooden supports include their low cost, low weight and flexibility during an earthquake. We must not forget about the general availability of wooden supports. The low weight of the supports makes it easier to install them, and also simplifies the delivery and unloading/loading of the supports at the preparatory stage of work. But wooden supports have more than enough disadvantages.

Disadvantages of wooden supports

1. Firstly, wooden supports burn well;
2. Being biological material, they rot, mold, and are corroded by bugs;
3. In the rain they get wet, swell, and crack.

But in defense of wooden poles, it is worth noting that modern technologies for impregnating poles, and this is impregnation of 100% sapwood of a pole, manufacturers guarantee a 50-year service life of wooden poles, even buried in the ground.

Note: Sapwood is the weak layer of wood found between the bark and the core of a log.

For more details on the designs of wooden poles, read the article: Wooden power line poles.

• Standards: GOST 9463-88, GOST 20022.0-93.

To reduce the contact of wood with the ground, prefabricated supports were used.

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Prefabricated supports

The prefabricated support consists of two parts. The lower part is called the stepson and is made of reinforced concrete, the upper part is a wooden pole. The two parts are connected with steel wire in two places. It is worth noting that instead of a reinforced concrete stepson, a wooden stepson can be used. Prefabricated supports also include supports assembled from a reinforced concrete frame and a metal upper part.

For more details on the designs of prefabricated poles, read the separate article: Prefabricated power line poles.

Reinforced concrete supports, reinforced concrete pillars

Reinforced concrete supports have long replaced wooden supports. They have firmly won the love and recognition of both electricians and customers. And there are several reasons for this.

• Reinforced concrete supports are not subject to damage typical of wooden supports;
• The service life of reinforced concrete supports is practically unlimited;
• Inside the concrete support there is reinforcement, which is used to re-ground the overhead lines. Moreover, the ends of the grounding reinforcement are brought out, above and below the pole. The outlet of the reinforcement simplifies installation, and the protection of the grounding descent with concrete increases electrical safety.

Reinforced concrete supports are marked as SV 95/105/110/164 and are intended for overhead lines of various capacities. Let's look at the photo.

• Regulatory documents: TU 5863-007-00113557-94

Metal power line supports

For overhead power lines of high power and extremely high currents, metal supports are used. Despite the fact that this type of support is made of special steel, they are “afraid” of corrosion and to protect against it, metal supports are coated with an anti-corrosion compound. Depending on the size of the support, the metal support can be prefabricated or welded. The prefabricated support is delivered to the site separately.

They are assembled locally and installed on a pre-prepared foundation. Installation of a metal support is a complex technological process, using traction mechanisms, usually tractors. The support is bolted to the foundation, pre-aligned strictly vertically. Metal supports are practically not used in private housing construction and in countryside partnerships of various types, with the exception of round metal poles.

There are so many designs of metal supports that I had to write a separate article: Metal supports and their designs.

Designed to hold wires suspended. These include lattice and multifaceted racks, traverses, and foundations. They can have different sizes and shapes. The production of power line supports involves the use of various materials. These structures are made of reinforced concrete and metal. The following types of supports are distinguished by purpose:

• Anchor;
• Intermediate;
• End;
• Angular.

Anchor wires are installed to limit anchor spans and in places where the number or type of wires changes. Installation of intermediate supports is carried out on straight sections of the electrical wiring route. Corner structures are used where it changes its direction. End - used at the beginning and end of the line. The plant for the production and installation of power transmission poles JSC PK "StalKonstruktsiya" produces intermediate supports of rigid and flexible construction in Moscow.

Antenna supports

They are used to secure antenna equipment at the required height. They are a rod metal structure in the shape of a regular tetrahedral pyramid. Depending on the signal strength, the level of communication lines raised may be different. Therefore, the height of these structures ranges from 30 to 80 m. They include:

• Bracket;
• Service area;
• Staircase with railing;
• Crossing area;
• Lattice support.

The main area of ​​application is radio relay communication lines. The structures are secured using bolted connections. A vertical ladder for the movement of people is fixed in the internal shaft of the structure. The production of power line supports of this type is carried out in six standard sizes. In this case, sections 10 m long are used.

Communication towers

They are special towers that have increased load-bearing capacity and increased height. Their purpose is to accommodate sets of antenna equipment that provide communications. The production of metal structures of this type is carried out in 2 varieties - masts and towers.

The most popular of them are masts. They are made from rolled pipe and painted white or red. Among them are supports for cellular and radio communications, street lighting, masts for television and radio broadcasting. The most commonly used are three-section designs. Installation of radio masts is carried out in several stages using special equipment.

Power poles

Their purpose is to maintain electrical wires at the required distance from the surface of roofs, the ground and wires of other lines. Such structures have to function in various meteorological conditions, so they require strength. The production of power line supports is carried out on the basis of various materials. In rural areas, softwood is still widely used for 35 kV power lines.

The most modern option is multi-faceted steel structures galvanized by hot-dip galvanizing. The design period of their operation is 70 years.

Production and installation

In order for such structures to serve for a long time and reliably, they require careful design and high-quality manufacturing. Our metal structures plant produces and supplies power transmission line supports to many energy and manufacturing companies. The technological process consists of assembling the frame, conducting incoming inspection of raw materials, heat-moist processing of molded products, and output inspection of finished products.

The production of metal power transmission poles in Moscow uses pipe and sheet metal. It is made from high quality carbon steel. Raw materials entering production must be subjected to laboratory control in the form of chemical and spectral analysis.

After production, the products are transported on platforms in separate sections. Before installation of structures, marking of the route is carried out. Next, wells are drilled for their subsequent installation. The depth and diameter of the hole depend on the type of product and the type of soil. Installation of supports is carried out using cranes or manipulators.