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Section 2. Sewerage of electricity
Overhead power lines with voltage above 1 kV. Protection of overhead lines from environmental influences
Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)
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2.5.25. Metal supports and footboards, metal parts of reinforced concrete and wooden supports, concrete and reinforced concrete structures, as well as wood elements of wooden supports must be protected from corrosion, taking into account the requirements of building codes and regulations for the protection of building structures from corrosion. Where necessary, protection against electrical corrosion should be provided.
Steel poles, as well as steel elements and parts of reinforced concrete and wooden poles, as a rule, must be protected from corrosion by hot-dip galvanizing.
Corrosion protection must be carried out in the factory. It is allowed to perform it on specially equipped landfills.
2.5.26. Steel ropes used as lightning protection cables, braces and support elements must have a corrosion-resistant design, taking into account the type and degree of aggressiveness of the environment under operating conditions.
A protective lubricant must be applied to the lightning protection cable and guys during the construction of the overhead line.
2.5.27. On sections of overhead lines in mountainous conditions, if necessary, the following should be provided:
- cleaning slopes from overhanging stones dangerous for overhead lines;
- the location of the overhead line outside the zone of avalanches and rockfalls, and if this is not possible, then the wires and cables should be placed outside the zone of action of the avalanche air wave, as well as the calculated flight path of falling stones.
2.5.28. VL routes should be located outside the zone of landslide processes. If it is impossible to bypass such zones, engineering protection of overhead lines from landslides should be provided in accordance with building codes and rules for the protection of territories, buildings and structures from dangerous geological processes.
2.5.29. When passing overhead lines in rough terrain with solifluction phenomena, when placing supports on slopes, the underground part of supports and foundations should be calculated for an additional load from the pressure of a layer of sliding soil.
2.5.30. When overhead lines pass through subsiding soils, the supports, as a rule, should be installed on sites with a minimum catchment area with a set of anti-subsidence measures. Disturbance of vegetation and soil cover should be minimal.
2.5.31. When passing overhead lines on semi-fixed and loose sands, it is necessary to perform sand-fixing measures. Vegetation disturbance should be minimal.
2.5.32. It is recommended to install overhead line supports at a safe distance from the river bed with intensive bank erosion, taking into account the predicted channel movements and floodplain flooding, as well as outside places where there may be rain and other water flows, ice drifts, etc. If it is justified that it is impossible to install supports in in safe places, it is necessary to take measures to protect the supports from damage (special foundations, strengthening of banks, slopes, slopes, drainage, jet-directing dams, ice cutters and other structures).
The installation of supports in the zone of passage of predicted mud and stone mudflows is not allowed.
2.5.33. The use of poles with guy wires in sections of overhead lines up to 330 kV passing through cultivated lands is not allowed.
2.5.34. On sections of the route passing through cultivated lands, in populated areas and in places of cramped approaches to power plants and substations, it is recommended to use double-circuit and multi-circuit free-standing supports.
2.5.35. When passing overhead lines with wooden supports through forests, dry swamps and other places where ground fires are possible, one of the following measures should be provided:
- arrangement of a ditch with a depth of 0,4 m and a width of 0,6 m at a distance of 2 m around each support post;
- destruction of grass and shrubs and clearing them of an area with a radius of 2 m around each support;
- the use of reinforced concrete attachments, while the distance from the ground to the lower end of the rack must be at least 1 m.
Installation of wooden poles for overhead lines of 110 kV and higher in areas where ground fires or peat fires are possible is not recommended.
2.5.36. In areas where large birds live, to protect isolation from pollution, regardless of the degree of environmental pollution (see Chapter 1.9), as well as to prevent the death of birds, the following should be done:
- do not use VL supports with pin insulators;
- on the traverses of the poles of 35-220 kV overhead lines, including in the places of attachment of the supporting garlands of insulators, as well as on cable racks, to exclude the possibility of landing or nesting of birds, provide for the installation of anti-bird barriers;
- close the upper openings of the hollow racks of reinforced concrete supports with caps.
2.5.37. In areas with a highly aggressive degree of environmental impact, in areas of salt marshes, saline sands, sandy deserts, in coastal areas of seas and salt lakes with an area of more than 10000 m2, as well as in places where corrosion damage to the metal of insulators, linear fittings, wires and cables has been established during operation , grounding conductors, it is necessary to provide:
- insulators and linear fittings in tropical design, if necessary with additional protective measures;
- corrosion-resistant wires (see also 2.5.80), cables and cable support elements (see also 2.5.26);
- increase in the section of the elements of grounding devices, the use of galvanized ground electrodes.
 See other articles Section Rules for the installation of electrical installations (PUE).
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