Reinforced concrete racks for power lines

The supply of electricity from power plants to consumers is carried out through power lines, which are based, as a rule, on reinforced concrete racks for power transmission towers. Without them, it would be impossible to organize the transmission of electricity over long distances. Next, we take a closer look at what these supports are, and what types they are.

General information

Initially, wooden poles served as power transmission poles, which quickly fell into disrepair and did not have sufficient strength. As a result, it was decided to replace them with reinforced concrete structures.

For the first time in the Soviet Union, they appeared in 1933, however, they became widespread in the 1950s. Since then, reinforced concrete supports have gained great popularity as a result of simple construction and long service life. In addition, their undeniable advantage is the low price.

Due to water resistance and high frost resistance of concrete, such supports are recommended for use in any climatic conditions.

Types of racks and scope

To date, produce reinforced concrete supports of the following types:

Classification by purpose

By appointment, the racks are divided into the following types:

• Intermediate - designed to hold the weight of cables and wires. Such structures are not designed for horizontal loads. Apply to direct sections of power lines.
• Анкерные - used to compensate for the difference in the tension of the wires. Mounted on direct sections of power lines.
• Corner - designed to compensate for the tension of the wires when turning tracks. Used in places of power lines turning. When turning to 30 ° degrees, intermediate corner posts are used, for corners over 30 ° - anchor-angle supports.
• Terminal - designed to compensate for the unilateral tension of the cables and wires at the end of the lines.
• Transposition - used to change the location of the cables and wires on the supports.
• Branching - designed to organize branches of power lines.
• Cross - used at the intersection of two power lines.

Features of reinforced concrete pillars

All power transmission poles are made from environmentally friendly materials of high quality, which correspond to certain state standards. In addition, they must pass a strict multi-level quality control.

Thanks to the use of special anti-corrosion concrete, the products have an excellent service life. It should also be noted that engineers are constantly improving the design of the racks, and also use new alloys for their manufacture. As a result, the strength and reliability of the supports is constantly increasing.

Depending on the application, the racks from which they are made may vary. For example, if the product is intended for the area where there are severe frosts in winter, then a special natural component is added to the concrete, which prevents its cracking from exposure to low temperatures. For arranging transmission lines in areas with high seismic activity, supports with increased wall thickness are used.

Note! The cost of racks depends not only on the materials that were used for their manufacture, but also on the configuration. For example, a reinforced concrete rack CB 110 - 5 with the presence of brackets and other fasteners will have an increased cost.

If the supports need to take a large load, in cases where the distance between the supports is about 300 meters, spatial supports are used. Their elements are manufactured by centrifugation.

Virtues

Due to the properties of the supports, they can be used even in adverse environmental conditions, including:

• In solid, liquid and gaseous non-aggressive and aggressive environment. This property is due to the fact that the products have good corrosion resistance.
• With an average temperature of up to -55 degrees Celsius inclusive.
• With seismicity up to 7 points.
• In areas that are characterized by strong gusts of wind.

In general, it can be said that the scope of application of the supports is not limited to the terrain features and environmental conditions.

As for their other advantages, the following points can be highlighted:

• Relative cheapness;
• High level of typification and unification;
• The presence in the country of a powerful production base;
• Long service life, which is 40-60 years.

disadvantages

Of course, along with the advantages, there are some disadvantages:

• Reinforced concrete supports withstand maximum loads several times smaller than metal.
• For the construction of lines it is necessary to use twice as many supports.
• Requires additional shipping costs.
• Loading requires the use of special equipment, since even a team of workers with their own hands cannot carry it out.

Marking Interpretation

Marking supports, as it is not difficult to guess, carries some information about the product.

It is deciphered as follows:

• The first letters indicate the type of support;
• Numbers - indicate the length of the product in decimeters;
• The number after the hyphen indicates the calculated bending moment.

For example, the reinforced concrete rack CB 95 - 3:

• Vibration stand;
• Product length 96 decimeters;
• Estimated bending moment - 3 ts * m.

Accordingly, the reinforced concrete pillar CB 95 - 2 has the same parameters, but its calculated bending moment is 2 3 tf * m.

Installation features

The brief installation instructions for the supports are as follows:

• Work begins with the laying of parts of the supports along the route, for subsequent assembly.
• Then dug up the cylindrical trenches, in the places of installation of the racks.
• Next, the assembled structures are lifted with a crane to the design position and installed in prepared pits. In soils with an insignificant bearing capacity, the strength of installation is achieved by fixing the supports with crossbars and installing them on special plates.
• Then the pit is filled with sand and gravel.
• For installation of braces install anchor plates at the design distance from the racks.

Note! During the work with concrete plates their mechanical processing can be necessary. In this case, diamond tools are used as the most effective. For example, diamond drilling of holes in concrete may be required for mounting anchors or cutting reinforced concrete with diamond circles.

Conclusion

Reinforced concrete racks are used in the construction of power lines of all voltage levels. Due to a number of their advantages, more than half of the power lines in our country are built with their use.

Moreover, with the development of technology, the structures and materials of the supports are also constantly being improved, so over time they do not lose their relevance. From the video in this article, you can get more information on this topic.