How the supports of overhead lines leading to the consumer are grounded. Grounding of overhead power lines Grounding. Surge protection

DEVELOPED taking into account the requirements of state standards, building codes and regulations, recommendations of scientific and technical councils for reviewing draft chapters. The draft chapters were reviewed by the working groups of the Coordinating Council for the revision of the EMP

PREPARED BY JSC "ROSEP", co-executor - JSC "Firma ORGRES"

AGREED in in due course with Gosstroy of Russia, Gosgortekhnadzor of Russia, RAO "UES of Russia" (JSC "VNIIE") and submitted for approval by Gosenergonadzor of the Ministry of Energy of Russia

From October 1, 2003, Chapter 2.4 of the "Electrical Installation Rules" of the sixth edition becomes invalid

The requirements of the Electrical Installation Rules are mandatory for all organizations, regardless of ownership and organizational and legal forms, as well as for individuals employed entrepreneurial activity without forming a legal entity.

Application area. Definitions

2.4.1. This chapter of the Rules applies to overhead power lines alternating current voltage up to 1 kV, performed using insulated or bare wires.

Additional requirements for overhead lines up to 1 kV are given in Ch. 2.5, 6.3 and 7.7.

Cable inserts in the line and cable branches from the line must be carried out in accordance with the requirements of Ch. 2.3.

2.4.2. Overhead line (VL) of power transmission with voltage up to 1 kV - a device for the transmission and distribution of electricity through insulated or uninsulated wires located on outdoors and attached with linear fittings to supports, insulators or brackets, to the walls of buildings and to engineering structures.

An overhead power line with a voltage of up to 1 kV using self-supporting insulated wires (SIP) is designated VLI.

Self-supporting insulated wire - insulated conductors twisted into a bundle, and the carrier conductor can be either insulated or uninsulated. The mechanical load can be taken either by the carrier conductor or by all conductors of the bundle.

2.4.3. Highway VL - a section of the line from the supply transformer substation to the end support.

Linear branches or branches to the input can be connected to the overhead line.

Linear branch from the overhead line - a section of the line connected to the main overhead line, having more than two spans.

A branch from the overhead line to the input is the section from the support of the main line or linear branch to the clamp (input insulator).

A branch from the VLI is allowed to be performed in the span.

2.4.4. The state of the overhead line in the calculations of the mechanical part:

• normal mode - mode with unbroken wires;
• emergency mode - mode with broken wires;
• installation mode - mode in the conditions of installation of supports and wires.

Mechanical calculation of overhead lines up to 1 kV in emergency mode is not performed.

General requirements

2.4.5. The mechanical calculation of the elements of the overhead line should be carried out according to the methods described in Ch. 2.5.

2.4.6. Overhead power lines should be placed so that the supports do not block the entrances to buildings and entrances to courtyards and do not impede the movement of vehicles and pedestrians. In places where there is a danger of collision with vehicles (at the entrances to yards, near exits from roads, at the intersection of roads), the supports must be protected from collision (for example, by bollards).

2.4.7. On the overhead line supports at a height of at least 2 m from the ground after 250 m on the overhead line, the following should be installed (applied): the serial number of the support; posters showing the distances from the overhead line pole to the cable communication line (on poles installed at a distance of less than 4 m from the communication cables), width security zone and phone owner VL.

2.4.8. When passing VLI through forests and green spaces, clearing is not required. At the same time, the distance from the wires to trees and bushes with the largest SIP sag and their largest deviation should be at least 0.3 m.

When passing overhead lines with uninsulated wires through forests and green spaces, cutting down the clearing is not necessary. At the same time, the distance from the wires with the largest sag or the largest deviation to trees and bushes should be at least 1 m.

The distance from insulated wires to green spaces should be at least 0.5 m.

2.4.9. The structures of the overhead line supports must be protected from corrosion, taking into account the requirements of 2.5.25, 2.5.26 and building codes and regulations.

2.4.10. Protection of overhead lines from electrical overloads should be carried out in accordance with the requirements of Ch. 3.1.

Climatic conditions

2.4.11. Climatic conditions for the calculation of overhead lines up to 1 kV in normal mode should be taken as for overhead lines up to 20 kV in accordance with 2.5.38 - 2.5.74. In this case, for overhead lines up to 1 kV, the following should be taken:

• when calculating according to 2.5.52: Cx= 1.1 - for SIP, free or covered with ice;
• when calculating according to 2.5.54 and 2.5.55:
• γnw = γng = 0.8 - for single-circuit overhead lines;
• γnw = γng = 0.9 - for single-circuit overhead lines with suspension on PV supports;
• γnw = 1.0 and γng = 1.2 - for double-circuit and multi-circuit overhead lines, as well as when hanging on the supports of overhead lines of a self-supporting non-metallic optical cable (OKSN);
• γp = 1.0 and K1 = 1.0 - in all cases.

2.4.12. The calculation of the span length of the branch from the overhead line to the input according to 2.4.20 must be carried out in icy conditions for two cases:

1. wind direction at an angle of 90º to the axis of the overhead line, the wires of the overhead line are covered with ice be, the thickness of the ice wall on the branch wires b0 = 0.5 be;
2. wind direction along the overhead line (angle 0º), ice wall thickness on branch wires b0 = be.

In this case, in both cases, one should take into account the reduction in the tension of the branch wires when the top of the support is deflected.

Wires. Linear reinforcement

2.4.13. On overhead lines, as a rule, self-supporting insulated wires (SIPs) should be used.

SIP should be classified as protected, have insulation made of slow-burning, light-stabilized synthetic material that is resistant to ultraviolet radiation and ozone.

2.4.14. According to the conditions of mechanical strength on the mains of the overhead line, on the linear branch from the overhead line and on the branches to the inputs, wires with the minimum sections indicated in tables 2.4.1 and 2.4.2 should be used.

Table 2.4.1 Minimum allowable sections of insulated wires

* In parentheses is the cross section of the core of self-supporting insulated wires twisted into a bundle, without a carrier wire.

Table 2.4.2 Minimum allowable sections of bare and insulated wires

2.4.15. When constructing overhead lines in places where operating experience has established the destruction of wires from corrosion (the coasts of the seas, salt lakes, industrial areas and areas of saline sands), as well as in places where, based on survey data, it is possible, self-supporting insulated wires with an insulated core should be used. .

2.4.16. The overhead line, as a rule, should be carried out with wires of a constant cross section.

2.4.17. Mechanical calculation of wires must be carried out according to the method of permissible stresses for the conditions specified in 2.5.38 - 2.5.74. In this case, the voltages in the wires should not exceed the allowable voltages given in Table. 2.4.3, and the distances from wires to the ground surface, intersected structures and grounded support elements must meet the requirements of this chapter.

The calculation uses the parameters of the wires given in Table. 2.5.8.

Table 2.4.3 Permissible mechanical stress in the wires of overhead lines up to 1 kV

2.4.18. All types of mechanical loads and impacts on SIP with a carrier core should be taken by this core, and on SIP without a carrier wire, all cores of a twisted bundle should be perceived.

2.4.19. The length of the span of the branch from the overhead line to the input should be determined by calculation depending on the strength of the support on which the branch is performed, the height of the suspension of the branch wires on the support and at the input, the number and cross section of the wires of the branch wires.

At distances from the overhead line to the building exceeding the calculated span of the branch, the required number of additional supports is installed.

2.4.20. The choice of the section of current-carrying conductors for a long time admissible current should be carried out taking into account the requirements of Ch. 1.3.

The cross section of current-carrying conductors must be checked according to the condition of heating during short circuits (SC) and for thermal stability.

2.4.21. Fastening, connection of the SIP and connection to the SIP should be done as follows:

1. fastening the wire of the VLI highway on intermediate and angular intermediate supports - using supporting clamps;
2. fastening the wire of the VLI main on anchor-type supports, as well as the end fastening of the branch wires on the VLI support and at the input - using tension clamps;
3. connection of the VLI wire in the span - using special connecting clamps; in the loops of anchor-type supports, it is allowed to connect an uninsulated carrier wire using a ram clamp. Connecting clamps designed to connect the carrier wire in the span must have a mechanical strength of at least 90% of the breaking force of the wire;
4. connection of the phase wires of the VLI highway - using connecting clamps having an insulating coating or a protective insulating sheath;
5. connection of wires in the span of the branch to the input is not allowed;
6. connection of grounding conductors - using flat clamps;
7. branch clamps should be used in the following cases:
   • branches from phase conductors, with the exception of SIP with all carrier conductors of the bundle;
   • branches from the carrier core.

2.4.22. Fastening of supporting and tension clamps to VLI supports, walls of buildings and structures should be carried out using hooks and brackets.

2.4.23. The design forces in the support and tension clamps, attachment points and brackets in normal mode should not exceed 40% of their mechanical breaking load.

2.4.24. Wire connections in spans of overhead lines should be made using connecting clamps that provide mechanical strength of at least 90% of the breaking force of the wire.

In one span of overhead lines, no more than one connection is allowed for each wire.

In the spans of the intersection of overhead lines with engineering structures, the connection of overhead lines is not allowed.

The connection of wires in the loops of the anchor supports should be made using clamps or welding.

Wires of different brands or sections should be connected only in the anchor support loops.

2.4.25. It is recommended to fasten uninsulated wires to insulators and insulating traverses on overhead line supports, with the exception of supports for crossings, as a single one.

Fastening of bare wires to pin insulators on intermediate supports should be carried out, as a rule, on the neck of the insulator on its inner side with respect to the support post.

2.4.26. Hooks and pins should be calculated in the normal mode of operation of the overhead line according to the method of breaking loads.

In this case, the forces shall not exceed the values ​​given in 2.5.101.

Arrangement of wires on poles

2.4.27. On supports, any arrangement of insulated and uninsulated wires of overhead lines is allowed, regardless of the area of ​​\u200b\u200bclimatic conditions. The neutral wire of overhead lines with bare wires, as a rule, should be located below the phase wires. Insulated outdoor lighting wires laid on VLI supports can be placed above or below the SIP, and also be twisted into a SIP bundle. Uninsulated and insulated outdoor lighting wires laid on overhead line supports should, as a rule, be located above the PEN (PE) conductor of the overhead line.

2.4.28. Devices mounted on supports for connecting electrical receivers must be placed at a height of at least 1.6 m from the ground.

Protective and sectioning devices installed on supports should be placed below the wires of the overhead line.

2.4.29. The distances between uninsulated wires on the support and in the span, according to the conditions of their convergence in the span with the largest sag up to 1.2 m, must be at least:

• at vertical arrangement wires and the location of wires with a horizontal displacement of not more than 20 cm: 40 cm in I, II and III regions on ice, 60 cm in IV and special regions on ice;
• at other locations of wires in all areas on ice at wind speed on ice: up to 18 m / s - 40 cm, more than 18 m / s - 60 cm.

With the largest sag of more than 1.2 m, the indicated distances must be increased in proportion to the ratio of the largest sag to the sag of 1.2 m.

2.4.30. The vertical distance between insulated and non-insulated wires of overhead lines of different phases on a support at a branch from an overhead line and at the intersection of different overhead lines on a common support must be at least 10 cm.

The distance from the wires of the overhead line to any support elements must be at least 5 cm.

2.4.31. When jointly suspended on common supports of VLI and VL up to 1 kV, the vertical distance between them on the support and in the span at an ambient temperature of plus 15 ºС without wind should be at least 0.4 m.

2.4.32. When two or more VLIs are jointly suspended on common supports, the distance between the SIP bundles must be at least 0.3 m.

2.4.33. When jointly suspended on common supports of wires of overhead lines up to 1 kV and wires of overhead lines up to 20 kV, the vertical distance between the nearest wires of overhead lines of different voltages on a common support, as well as in the middle of the span at an ambient temperature of plus 15 ºС without wind, should be at least:

• 1.0 m - when hanging SIP with an insulated carrier and with all carrier wires;
• 1.75 m - when hanging SIP with an uninsulated carrier wire;
• 2.0 m - when hanging uninsulated and insulated wires of overhead lines up to 1 kV.

2.4.34. When hanging on common supports wires of overhead lines up to 1 kV and protected wires of overhead lines 6-20 kV (see 2.5.1), the vertical distance between the nearest wires of overhead lines up to 1 kV and overhead lines 6-20 kV on the support and in the span at a temperature of plus 15 ºС without wind should be at least 0.3 m for SIP and 1.5 m for uninsulated and insulated wires of overhead lines up to 1 kV.

Insulation

2.4.35. Self-supporting insulated wire is attached to the supports without the use of insulators.

2.4.36. On overhead lines with uninsulated and insulated wires, regardless of the material of the supports, the degree of atmospheric pollution and the intensity of lightning activity, insulators or traverses made of insulating materials should be used.

Selection and calculation of insulators and fittings are carried out in accordance with 2.5.100.

2.4.37. On the supports of branches from overhead lines with uninsulated and insulated wires, as a rule, multi-neck or additional insulators should be used.

Grounding. Surge protection

2.4.38. Grounding devices designed for re-grounding, protection against lightning surges, grounding of electrical equipment installed on overhead line supports must be made on the overhead line supports. The resistance of the grounding device must be no more than 30 ohms.

2.4.39. metal supports, metal constructions and reinforcement of reinforced concrete support elements must be connected to the PEN conductor.

2.4.40. On reinforced concrete poles, the PEN conductor should be connected to the reinforcement of reinforced concrete pillars and struts of the poles.

2.4.41. Hooks and pins of wooden poles of overhead lines, as well as metal and reinforced concrete poles when suspended on them with an insulated carrier conductor or with all carrier conductors of the bundle, are not subject to grounding, with the exception of hooks and pins on the poles, where repeated grounding and grounding are performed to protect against atmospheric overvoltages.

2.4.42. Hooks, pins and fittings of overhead lines with a voltage of up to 1 kV, limiting the crossing span, as well as supports on which joint suspension is carried out, must be grounded.

2.4.43. On wooden poles Overhead lines at the transition to the cable line, the grounding conductor must be connected to the PEN conductor of the overhead line and to the metal sheath of the cable.

2.4.44. Protective devices installed on overhead lines for protection against lightning surges must be connected to the grounding conductor with a separate descent.

2.4.45. The connection of the grounding conductors to each other, their connection to the upper grounding outlets of the racks of reinforced concrete supports, to hooks and brackets, as well as to grounded metal structures and to grounded electrical equipment installed on overhead line supports, must be carried out by welding or bolted connections.

The connection of grounding conductors (descents) to the grounding conductor in the ground must also be carried out by welding or have bolted connections.

2.4.46. In a populated area with one- and two-story buildings, overhead lines must have grounding devices designed to protect against atmospheric surges. The resistance of these grounding devices should be no more than 30 ohms, and the distances between them should be no more than 200 m for areas with up to 40 thunderstorm hours per year, 100 m for areas with more than 40 thunderstorm hours per year.

In addition, grounding devices must be made:

1. on supports with branches to the entrances to buildings, in which a large number of people (schools, nurseries, hospitals) or who are of great material value (livestock and poultry premises, warehouses);
2. on the end supports of the lines having branches to the inputs, while the greatest distance from the adjacent grounding of the same lines should be no more than 100 m for areas with up to 40 and 50 m of thunderstorm hours per year - for areas with more than 40 thunderstorm hours per year .

2.4.47. At the beginning and end of each VLI line, it is recommended to install clamps on the wires for connecting voltage control devices and portable grounding.

Grounding lightning surge protection devices are recommended to be combined with the re-grounding of the PEN conductor.

2.4.48. Requirements for grounding devices for re-grounding and protective conductors are given in 1.7.102, 1.7.103, 1.7.126. As grounding conductors on overhead line supports, it is allowed to use round steel with an anti-corrosion coating with a diameter of at least 6 mm.

2.4.49. Guys of overhead lines must be connected to the ground conductor.

supports

2.4.50. Supports made of various materials can be used on overhead lines.

For overhead lines, the following types of supports should be used:

1. intermediate, installed on straight sections of the overhead line route. These supports in normal operating modes should not perceive the forces directed along the overhead line;
2. anchor, installed to limit the anchor span, as well as in places where the number, grades and cross sections of overhead lines change. These supports should perceive, in normal operating modes, the forces from the difference in the tension of the wires directed along the overhead line;
3. angular, installed in places where the direction of the overhead line route changes. These supports, under normal operating conditions, must perceive the resulting load from the tension of the wires of adjacent spans. Corner supports can be intermediate and anchor type;
4. terminal, installed at the beginning and end of the overhead line, as well as in places limiting cable inserts. They are anchor-type supports and must perceive, in normal operating modes of overhead lines, the one-sided tension of all wires.

Supports on which branches from overhead lines are carried out are called branch; supports on which the crossing of overhead lines is carried out different directions or the intersection of overhead lines with engineering structures, - cross. These supports can be of all the above types.

2.4.51. Support structures should provide the ability to install:

• street lighting fixtures of all types;
• end cable couplings;
• protective devices;
• sectioning and switching devices;
• cabinets and shields for connecting electrical receivers.

2.4.52. Supports, regardless of their type, can be free-standing, with braces or braces.

Support guys can be attached to anchors installed in the ground, or to stone, brick, reinforced concrete and metal elements of buildings and structures. The cross section of the guys is determined by calculation. They can be stranded or round steel. The cross section of single-wire steel braces must be at least 25 mm2.

2.4.53. The overhead line supports must be calculated according to the first and second limit state in the normal operation of the overhead line for climatic conditions according to 2.4.11 and 2.4.12.

Intermediate supports must be designed for the following combinations of loads:

• simultaneous action of transverse wind load on wires, free or covered with ice, and on the structure of the support, as well as the load from the tension of branch wires to inputs, free from ice or partially covered with ice (according to 2.4.12);
• on the load from the tension of the wires of the branches to the inputs covered with ice, while it is allowed to take into account the deviation of the support under the action of the load;
• on a conditional design load equal to 1.5 kN, applied to the top of the support and directed along the axis of the overhead line.

Corner supports (intermediate and anchor) must be designed for the resulting load from the tension of the wires and wind load on wires and support structure.

Anchor supports must be designed for the difference in tension of the wires of adjacent spans and the transverse load from wind pressure with and without ice on the wires and the support structure. For the smallest value of the tension difference, 50% of the largest value of the unilateral tension of all wires should be taken.

End supports must be designed for one-sided tension of all wires.

Branch supports are calculated for the resulting load from the tension of all wires.

2.4.54. When installing supports on flooded sections of the route, where soil erosion or ice drift is possible, the supports must be strengthened (earth filling, paving, banquettes, installation of ice cutters).

Dimensions, intersections and convergence

2.4.55. The vertical distance from the VLI wires to the ground surface in populated and uninhabited areas to the ground and the carriageway of the streets must be at least 5 m. It can be reduced in hard-to-reach areas up to 2.5 m and inaccessible (mountain slopes, rocks, cliffs) - up to 1 m.

When crossing the impassable part of the streets with branches from the VLI to the inputs to the buildings, the distance from the SIP to the sidewalks of the footpaths can be reduced to 3.5 m.

The distance from the SIP and insulated wires to the ground on the branches to the input must be at least 2.5 m.

The distance from bare wires to the ground surface on the branches to the inputs must be at least 2.75 m.

2.4.56. The distance from the wires of the overhead line in populated and uninhabited areas with the largest sag of the wires to the ground and the carriageway of the streets must be at least 6 m. The distance from the wires to the ground can be reduced in hard-to-reach areas to 3.5 m and in inaccessible areas (mountain slopes , rocks, cliffs) - up to 1 m.

2.4.57. The horizontal distance from the SIP at their greatest deviation to the elements of buildings and structures should be at least:

• 1.0 m - to balconies, terraces and windows;
• 0.2 m - to the blank walls of buildings, structures.

It is allowed to pass VLI and VL with insulated wires over the roofs of buildings and structures (except for those specified in Chapters 7.3 and 7.4), while the vertical distance from them to the wires must be at least 2.5 m.

2.4.58. The horizontal distance from the wires of the overhead line with their greatest deviation to buildings and structures should be at least:

• 1.5 m - to balconies, terraces and windows;
• 1.0 m - to blank walls.

The passage of overhead lines with bare wires over buildings and structures is not allowed.

2.4.59. The smallest distance from the SIP and wires of overhead lines to the surface of the earth or water, as well as to various structures when passing overhead lines over them, is determined when highest temperature air without taking into account the heating of overhead lines by electric current.

2.4.60. When laying along the walls of buildings and structures, the minimum distance from the SIP should be:

• with horizontal laying
• above the window, front door - 0.3 m;
• under the balcony, window, cornice - 0.5 m;
• to the ground - 2.5 m;
• with vertical laying
• to the window - 0.5 m;
• to the balcony front door- 1.0 m.

The clear distance between the SIP and the wall of the building or structure must be at least 0.06 m.

2.4.61. Horizontal distances from the underground parts of supports or earthing of supports to underground cables, pipelines and ground columns for various purposes must be at least those given in Table 2.4.4.

Table 2.4.4 The smallest allowable horizontal distance from the underground parts of supports or grounding devices of supports to underground cables, pipelines and ground columns

2.4.62. When crossing overhead lines with various structures, as well as with streets and squares of settlements, the intersection angle is not standardized.

2.4.63. Crossing overhead lines with navigable rivers and canals is not recommended. If it is necessary to perform such an intersection, overhead lines must be constructed in accordance with the requirements of 2.5.268 - 2.5.272. When crossing non-navigable rivers and canals, the shortest distances from the overhead line wires to the highest water level should be at least 2 m, and to the ice level - at least 6 m.

2.4.64. The intersection and convergence of overhead lines with voltage up to 1 kV with overhead lines with voltage above 1 kV, as well as the joint suspension of their wires on common supports, must be carried out in compliance with the requirements given in 2.5.220 - 2.5.230.

2.4.65. It is recommended to cross overhead lines (VLI) up to 1 kV on cross supports; their intersection in the span is also allowed. The vertical distance between the wires of intersecting overhead lines (VLI) must be at least: 0.1 m on the support, 1 m in the span.

2.4.66. At the intersection of overhead lines up to 1 kV, intermediate supports and anchor-type supports can be used with each other.

When crossing overhead lines up to 1 kV between themselves in the span, the intersection should be chosen as close as possible to the support of the upper crossing overhead line, while the horizontal distance from the supports of the crossing overhead line to the wires of the crossed overhead line with their greatest deviation should be at least 2 m.

2.4.67. With parallel passage and approach of overhead lines up to 1 kV and overhead lines above 1 kV, the horizontal distance between them must be at least those specified in 2.5.230.

2.4.68. Joint suspension of wires of overhead lines up to 1 kV and uninsulated wires of overhead lines up to 20 kV on common supports is allowed subject to the following conditions:

1. wires of overhead lines up to 20 kV should be located above the wires of overhead lines up to 1 kV;
2. wires of overhead lines up to 20 kV, fixed on pin insulators, must have a double fastening.

2.4.69. When hanging on common supports wires of overhead lines up to 1 kV and protected wires of 6-20 kV overhead lines, the following requirements must be observed:

1. VL up to 1 kV must be carried out according to the design climatic conditions VL up to 20 kV;
2. wires of VLZ 6-20 kV should be located, as a rule, above the wires of overhead lines up to 1 kV;
3. fastening of wires of VLZ 6-20 kV on pin insulators must be reinforced.

2.4.70. When crossing an overhead line (VLI) with an overhead line with a voltage above 1 kV, the distance from the wires of the crossing overhead line to the crossed overhead line (VLI) must comply with the requirements given in 2.5.221 and 2.5.227.

The cross section of the wires of the crossed overhead line should be taken in accordance with 2.5.223.

Intersections, convergence, joint suspension of overhead lines with communication lines, wire broadcasting and RK

2.4.71. The angle of intersection of the overhead line with the LAN * and LPV should be as close as possible to 90º. For cramped conditions, the intersection angle is not standardized.

According to their purpose, overhead communication lines are divided into long-distance telephone lines (MTS), rural telephone lines (STS), city telephone lines (GTS), wire broadcasting lines (LPV).

In terms of importance, overhead communication lines and wire broadcasting are divided into classes:

• MTS and STS lines: MTS trunk lines connecting Moscow with republican, regional and regional centers and the latter between themselves, and lines of the Ministry of Railways, passing along railways and on the territory of railway stations (class I); intrazonal MTS lines connecting republican, krai and regional centers with regional centers and the latter among themselves, and STS connecting lines (class II); STS subscriber lines (class III);
• GTS lines are not divided into classes;
• wire broadcasting lines: feeder lines with a rated voltage above 360 ​​V (class I); feeder lines with rated voltage up to 360 V and subscriber lines with voltage 15 and 30 V (class II).

* LAN should be understood as communication lines of the Ministry of Communications of the Russian Federation and other departments, as well as signaling lines of the Ministry of Railways.

LPV should be understood as wire broadcasting lines.

2.4.72. The vertical distance from the wires of the overhead line to the wires or overhead cables of the LAN and LPV in the crossing span with the largest sag of the wire of the overhead line should be:

• from SIP and insulated wires - at least 1 m;
• from bare wires - at least 1.25 m.

2.4.73. The vertical distance from the wires of the overhead line up to 1 kV to the wires or overhead cables of the LS or LPV when crossing on a common support should be:

• between SIP and drugs or LPV - not less than 0.5 m;
• between the uninsulated wire of the overhead line and the LPV - at least 1.5 m.

2.4.74. The intersection of the wires of the overhead line with wires or overhead cables of the LS and LPV in the span should be as close as possible to the overhead line support, but not less than 2 m from it.

2.4.75. The intersection of overhead lines with LS and LPV can be performed according to one of the following options:

1. wires of overhead lines and insulated wires of LS and LPV;
2. wires of overhead lines and underground or overhead cable LS and LPV;
3. VL wires and uninsulated wires LS and LPV;
4. underground cable insert in overhead lines with insulated and uninsulated wires LS and LPV.

2.4.76. When crossing overhead lines with insulated wires LS and LPV, the following requirements must be observed:

1. the intersection of uninsulated overhead lines with LAN wires, as well as with LPV wires with a voltage above 360 ​​V, should be carried out only in the span. The intersection of uninsulated wires of overhead lines with wires of LPV with a voltage of up to 360 V can be performed both in the span and on a common support;
2. poles of overhead lines that limit the span of intersection with LS of trunk and intrazonal communication networks and connecting lines of STS, as well as LPV with voltage above 360 ​​V, must be of the anchor type. At the intersection of all other LS and LPV, intermediate-type overhead lines are allowed, reinforced with an additional prefix or strut;
3. VL wires should be located above the LS and LPV wires. On the supports that limit the crossing span, uninsulated and insulated wires of overhead lines must be double fastened, the self-supporting insulated wire is fixed with anchor clamps. Wires LS and LPV on the supports that limit the span of the crossing must have a double fastening. In cities and urban-type settlements, newly built HP and LPV are allowed to be placed above the wires of overhead lines with a voltage of up to 1 kV.

2.4.77. When crossing overhead lines with an underground or overhead cable LS and LPV, the following requirements must be met:

1. the distance from the underground part of a metal or reinforced concrete pole and the earthing of a wooden pole to the underground cable of the LS and LPV in a populated area should, as a rule, be at least 3 m. and LPV); at the same time, the cable must be laid in a steel pipe or covered with a channel or angle steel along the length on both sides of the support at least 3 m;
2. in an uninhabited area, the distance from the underground part or ground electrode of the overhead line support to the underground cable of the LS and LPV must be at least the values ​​\u200b\u200bgiven in Table. 2.4.5;
3. wires of overhead lines should, as a rule, be located above the overhead cable of the LS and LPV (see also 2.4.76, clause 4);
4. connection of wires of overhead lines in the span of intersection with the overhead cable of the LS and LPV is not allowed. The cross section of the SIP carrier core must be at least 35 mm2. VL wires must be multi-wire with a cross section of at least: aluminum - 35 mm2, steel-aluminum - 25 mm2; cross-section of the SIP core with all the carrier conductors of the bundle - at least 25 mm2;
5. the metal sheath of the overhead cable and the rope on which the cable is suspended must be grounded on supports that limit the crossing span;
6. the horizontal distance from the base of the cable support of the LS and LPV to the projection of the nearest wire of the overhead line on the horizontal plane must be at least the maximum height of the support of the crossing span.

Table 2.4.5 The shortest distance from the underground part and the ground electrode of the overhead line support to the underground cable of the LS and LPV in an uninhabited area

2.4.78. When crossing VLI with uninsulated wires LS and LPV, the following requirements must be observed:

1. the intersection of the VLI with the LS and LPV can be performed in the span and on the support;
2. VLI supports, limiting the span of intersection with the LS of the main and intrazonal communication networks and with the connecting lines of the STS, must be of the anchor type. When crossing all other LS and LPV on VLI, it is allowed to use intermediate supports reinforced with an additional prefix or strut;
3. the carrier core of the self-supporting insulated wire or bundle with all carrier conductors at the intersection must have a tensile strength factor at the highest design loads of at least 2.5;
4. VLI wires should be located above the LS and LPV wires. On the supports that limit the crossing span, the supporting wires of the self-supporting insulated wire must be fixed with tension clamps. VLI wires are allowed to be placed under the LPV wires. At the same time, the LPV wires on the supports that limit the crossing span must have a double fastening;
5. the connection of the carrier core and the carrier conductors of the SIP bundle, as well as the LS and LPV wires in the crossing spans is not allowed.

2.4.79. When crossing insulated and uninsulated wires of overhead lines with uninsulated wires of LS and LPV, the following requirements must be observed:

1. the intersection of the wires of the overhead line with the wires of the LAN, as well as the wires of the LPV with a voltage above 360 ​​V, should be carried out only in the span.
   The intersection of wires of overhead lines with subscriber and feeder lines of LPV with a voltage of up to 360 V is allowed to be carried out on overhead line supports;
2. VL supports limiting the crossing span must be of the anchor type;
3. LS wires, both steel and non-ferrous, must have a tensile strength factor at the highest design loads of at least 2.2;
4. VL wires should be located above the LS and LPV wires. On the supports that limit the crossing span, the wires of the overhead line must have a double fastening. Wires of overhead lines with a voltage of 380/220 V and below are allowed to be placed under the wires of the LPV and GTS lines. At the same time, the wires of the LPV and the GTS lines on the supports that limit the crossing span must have a double fastening;
5. connection of wires of overhead lines, as well as wires of LS and LPV in crossing spans is not allowed. VL wires must be multi-wire with sections not less than: aluminum - 35 mm2, steel-aluminum - 25 mm2.

2.4.80. When crossing an underground cable insert in an overhead line with uninsulated and insulated wires LS and LPV, the following requirements must be observed:

1. the distance from the underground cable insert in the overhead line to the LS and LPV support and its ground electrode must be at least 1 m, and when laying the cable in an insulating pipe - at least 0.5 m;
2. the horizontal distance from the base of the overhead line cable support to the projection of the nearest LS and LPV wire on a horizontal plane must be at least the maximum height of the crossing span support.

2.4.81. The horizontal distance between the VLI wires and the LS and LPV wires during parallel passage or approach must be at least 1 m.

When approaching overhead lines with air LS and LPV, the horizontal distance between the insulated and uninsulated wires of the overhead line and the wires of the LS and LPV must be at least 2 m. In cramped conditions, this distance can be reduced to 1.5 m. In all other cases, the distance between the lines should be not less than the height of the highest support of the overhead line, LS and LPV.

When approaching overhead lines with underground or overhead cables LS and LPV, the distances between them should be taken in accordance with 2.4.77, paragraphs 1 and 5.

2.4.82. The proximity of overhead lines with antenna structures of transmitting radio centers, receiving radio centers, dedicated receiving points for wire broadcasting and local radio nodes is not standardized.

2.4.83. The wires from the overhead line support to the entrance to the building should not intersect with the branch wires from the LS and LPV, and they should be located at the same level or above the LS and LPV. The horizontal distance between the wires of the overhead line and the wires of the LS and LPV, television cables and descents from radio antennas at the inputs must be at least 0.5 m for SIP and 1.5 m for uninsulated wires of overhead lines.

2.4.84. Joint suspension of the overhead cable of rural telephone communication and VLI is allowed if the following requirements are met:

1. the zero core of the SIP must be insulated;
2. the distance from the SIP to the STS overhead cable in the span and on the VLI support must be at least 0.5 m;
3. each VLI support must have a grounding device, while the grounding resistance should be no more than 10 ohms;
4. on each VLI support, the PEN conductor must be re-grounded;
5. the carrying rope of the telephone cable, together with the metal mesh outer cover of the cable, must be connected to the grounding conductor of each support by a separate independent conductor (descent).

2.4.85. Joint suspension on common supports of uninsulated wires of overhead lines, LS and LPV is not allowed.

Joint suspension of uninsulated wires of overhead lines and insulated wires of LPV is allowed on common supports. In this case, the following conditions must be met:

1. the rated voltage of the overhead line should be no more than 380 V;
2. the distance from the lower LPV wires to the ground, between the LPV circuits and their wires must comply with the requirements of the current rules of the Ministry of Communications of Russia;
3. uninsulated wires of overhead lines should be located above the wires of the LPV; at the same time, the vertical distance from the lower wire of the overhead line to the upper wire of the LPV should be at least 1.5 m on the support, and at least 1.25 m in the span; when the LPV wires are located on the brackets, this distance is taken from the lower wire of the overhead line, located on the same side as the LPV wires.

2.4.86. Joint suspension of SIP VLI with uninsulated or insulated wires LS and LPV is allowed on common supports. In this case, the following conditions must be met:

1. the rated voltage of the VLI should be no more than 380 V;
2. rated voltage LPV should be no more than 360 V;
3. the rated voltage of the LAN, the calculated mechanical stress in the wires of the LAN, the distances from the lower wires of the LAN and LPV to the ground, between the circuits and their wires must comply with the requirements of the current rules of the Ministry of Communications of Russia;
4. VLI wires up to 1 kV should be located above the LS and LPV wires; at the same time, the vertical distance from the SIP to the upper wire of the LS and LPV, regardless of their relative position, must be at least 0.5 m on the support and in the span. Wires VLI and LS and LPV are recommended to be placed on different sides of the support.

2.4.87. Joint suspension on common supports of uninsulated wires of overhead lines and LAN cables is not allowed. Joint suspension on common supports of wires of overhead lines with a voltage of not more than 380 V and cables of LPV is allowed subject to the conditions specified in 2.4.85.

The optical fibers of the JCLN shall comply with the requirements of 2.5.192 and 2.5.193.

2.4.88. Joint suspension on common supports of wires of overhead lines with a voltage of not more than 380 V and telemechanics wires is allowed subject to the requirements given in 2.4.85 and 2.4.86, and also if telemechanics circuits are not used as wired telephone communication channels.

2.4.89. On the supports of VL (VLI) it is allowed to suspend fiber-optic communication cables (OK):

• non-metallic self-supporting (OKSN);
• non-metallic, wound on a phase wire or a bundle of self-supporting insulated wire (OKNN).

Mechanical calculations of VL (VLI) supports with OKSN and OKNN should be made for the initial conditions specified in 2.4.11 and 2.4.12.

The overhead line supports on which the OK is suspended, and their fixing in the ground, must be calculated taking into account the additional loads that arise in this case.

The distance from OKSN to the ground surface in populated and uninhabited areas should be at least 5 m.

The distances between the wires of overhead lines up to 1 kV and OKSN on the support and in the span must be at least 0.4 m.

Intersections and convergence of overhead lines with engineering structures

2.4.90. When crossing and parallel following overhead lines with iron and highways the requirements set out in Sec. 2.5.

Crossings can also be carried out using a cable insert in the overhead line.

2.4.91. When approaching overhead lines with highways, the distance from the wires of the overhead line to road signs and their supporting cables must be at least 1 m. The supporting cables must be grounded with a grounding device resistance of not more than 10 ohms.

2.4.92. When crossing and approaching overhead lines with contact wires and carrying cables of tram and trolleybus lines, the following requirements must be met:

1. Overhead lines should, as a rule, be located outside the area occupied by contact network structures, including supports.
   In this zone, the overhead line supports should be of the anchor type, and the uninsulated wires should be double fastened;
2. VL wires should be located above the carrier cables of the contact wires. The wires of the overhead line must be multi-wire with a cross section of at least: aluminum - 35 mm2, steel-aluminum - 25 mm2, the SIP carrier core - 35 mm2, the cross section of the SIP core with all the carrier conductors of the bundle - at least 25 mm2. Connection of wires of overhead lines in crossing spans is not allowed;
3. the distance from the wires of the overhead line with the largest sag must be at least 8 m to the head of the rail of the tram line and 10.5 m to the carriageway of the street in the area of ​​the trolleybus line.
4. In this case, in all cases, the distance from the wires of the overhead line to the carrier cable or contact wire must be at least 1.5 m;
5. crossing overhead lines with contact wires at the locations of the crossbars is prohibited;
6. joint suspension on the supports of trolleybus lines of contact wires and wires of overhead lines with a voltage of not more than 380 V is allowed subject to the following conditions: the supports of trolleybus lines must have mechanical strength sufficient for hanging wires of overhead lines, the distance between the wires of overhead lines and the bracket or the device for attaching the supporting cable of the contact wires must be at least 1.5 m.

2.4.93. When crossing and approaching overhead lines with cable cars and elevated metal pipelines, the following requirements must be met:

1. The overhead line must pass under the cable car; the passage of overhead lines over the cable car is not allowed;
2. cable cars must have walkways or nets below to protect overhead lines;
3. when passing overhead lines under a cable car or under a pipeline, the wires of the overhead lines must be at a distance from them: at least 1 m - with the smallest sag of the wires to the walkways or fencing nets of the cable car or to the pipeline; not less than 1 m - with the largest sag and the largest deviation of the wires to the elements of the cable car or to the pipeline;
4. when crossing an overhead line with a pipeline, the distance from the wires of the overhead line with their largest sag to the pipeline elements must be at least 1 m. The overhead line supports that limit the span of the intersection with the pipeline must be of the anchor type. The pipeline in the crossing span must be grounded, the resistance of the grounding conductor is not more than 10 Ohm;
5. when parallel following the overhead line with a cable car or pipeline, the horizontal distance from the wires of the overhead line to the cable car or pipeline must be at least the height of the support, and in cramped sections of the route with the greatest deviation of the wires - at least 1 m.

2.4.94. When approaching overhead lines with fire and explosion hazardous installations and airfields, the requirements given in 2.5.278, 2.5.291 and 2.5.292 should be followed.

2.4.95. The passage of overhead lines up to 1 kV with insulated and non-insulated wires is not allowed on the territories of sports facilities, schools (general education and boarding schools), technical schools, preschool institutions (nurseries, kindergartens, orphanages), orphanages, children's playgrounds, as well as on the territories of children's health camps.

In the above territories (except for sports and playgrounds), the passage of VLI is allowed, provided that the zero conductor of the SIP must be isolated, and its total conductivity must be at least the conductivity of the phase conductor of the SIP

It is impossible to imagine modern civilization without electricity. A huge part of hydrocarbons is used to generate electricity.

However, electricity cannot be transported like oil or coal. For its transportation, power lines (TL) are used to provide electricity traffic. high power to the required distances. Bringing the parameters of the energy transmitted through them to the standards characteristic of its consumers implies the use transformer substations, which provide the necessary voltage in the network. Thus, all electrical installations are powered, from the light bulb in the room to industrial equipment.

To prevent injuries to service personnel and even more deaths, given the high voltage, grounding devices for overhead lines and substations are used. This publication aims to understand the reasons for their need, as well as the designs of these devices.

Why you need to ground power lines and substations

By and large, an overhead line (VL) is a series of pillars (supports) exposed to natural factors such as temperature extremes, precipitation, direct exposure to solar ultraviolet and others. Due to their influence, the properties of dielectrics can change and direct contact of the current-carrying parts of the cable with the support can occur. Among other things, there are frequent short-term voltage surges in the line with a significant excess of the nominal (permissible) value, which can lead to a short circuit between the cable and the structural elements of the support.

When touching such a pole, a person can be injured and even die. Therefore, the installation of grounding on an overhead line does not at all belong to the category of recommendations or whims of control authorities. This is dictated by the rules for the installation of electrical installations (PUE) as the main regulatory document regulating the requirements for power systems, including overhead lines. According to this document, grounding devices for overhead line supports are required.

The issue of lightning protection of structures stands apart. Supports can be made of wood, reinforced concrete or steel. For poles standing in an open field, sometimes having a very significant height, a lightning strike is by no means a rare occurrence. If for steel or reinforced concrete, which have good electrical conductivity and are incapable of burning, this will not cause serious damage, then for wooden structure risk of destruction or fire. Considering the colossal voltage of a lightning discharge, the destruction of dielectrics enclosing structural elements from the current-carrying parts of the overhead line, which, in turn, leads to an accident.

All this applies equally to substations. Until now, some of them are a large transformer in the middle of the field, feeding the farm, for example. Transformer installations are subject to all negative influences, as well as overhead lines. Even if this is not the case, they must comply with the requirements of the PUE.

A mast or substation equipped with a grounding device behaves differently. All the charge that hit the support will drain to the ground, given its low resistance and huge capacitance. This means that the structure will not be energized and will be safe for human life and health.

Primary requirements

According to the requirements of the PUE, almost every support must have a grounding device. It is necessary to prevent atmospheric overvoltage (lightning), to protect electrical equipment located on the mast, as well as to implement re-grounding. Its resistance should not exceed 30 ohms. Moreover, lightning rods and similar devices, must be connected to the grounding conductor by a separate conductor. Among other things, stretch marks installed for the stability of the support, if they are present in its design, are subject to mandatory grounding. All interconnections, drop and ground wires, for example, are preferably welded, and, for lack of opportunity, twisted with bolts. All parts of the grounding device must be made of steel with a diameter of at least 6 mm. The conductor itself and the joints must have an anti-corrosion coating. Usually this is a galvanized steel wire of the appropriate diameter.

Reinforced concrete poles

The overhead line grounding device depends on the material of the supports. When reinforced concrete structure all fittings protruding from above and below must be connected to the PEN conductor (zero bus), which subsequently plays the role of grounding. Hooks, brackets and other metal structures located on the support should also be attached to it. All this equally applies to the metal masts of overhead lines.

wooden poles

With wooden supports of overhead lines, the situation is somewhat different. Due to the dielectric properties of wood, each of the masts does not need a separate grounding device. It is installed only if there is a lightning rod or re-grounding on the mast. In addition, the metal sheath of the cable is connected to the PEN bus of the line at the transition points of the overhead line to the cable line.

low-rise buildings

All types of supports must be equipped with grounding devices, if we are talking about settlements with low-rise buildings (1 or 2 floors).

The distance between such masts depends on the average annual value of the hours in which a thunderstorm occurs. If this value does not exceed 40, then the gaps between supports with lightning rods should be less than 200 m. Otherwise, this distance is reduced to 100 m. or houses of culture, for example.

Installation of grounding switches

Grounding of overhead lines is carried out by vertical or horizontal grounding conductors. In the first case, these are steel pins buried or hammered into the ground, and in the second, they are strips of metal located parallel to the ground under its surface. The latter option is used for soil with high resistivity. After burying the contour, the earth is rammed to ensure its best contact with the metal. Then the resistance is measured at the grounding of the overhead line supports. It is the product of the value obtained by direct measurement by a factor depending on the type and size of the earth electrode, as well as climate zone(there are special tables).

Substation Features

Everything previously described applies to substations, despite the fact that they are under the roof. The only exception is that people are often or constantly there, and, therefore, special requirements are imposed on their grounding.

IN general case substation grounding consists of the following elements:

• inner contour;
• outer contour;
• object lightning protection device.

The substation's internal ground loop provides a simple and reliable ground connection for all devices inside the substation. To do this, a steel strip is fixed with dowels around the perimeter of all rooms of the facility at a height of 40 cm from the floor. The contours of all rooms, as well as their component parts, are connected by welding or threaded connections, if any. All metal parts not intended for the passage of current (instrument cases, fences, hatches, etc.) are connected to this bus. Such strips are equipped with threaded connections with washers of increased width and wing nuts. This allows you to get a reliable portable grounding. The zero bus of the power transformer, taking into account the circuit with a solidly grounded neutral, is connected to the resulting circuit.

Outer loop

The external ground loop is also closed. It is a horizontal steel strip earthing conductor connecting a certain number of vertical pins. The depth of this structure should be at least 70 cm from the surface, and the strip is placed edgewise.

It is required to locate the device along the perimeter of the building not exceeding a distance of 1 m from its walls or foundation slab. The total loop resistance cannot exceed 40 ohms if the soil resistivity is less than 1 kOhm * m in accordance with the PUE.

If the substation has metal roof, then it is grounded by connecting it to the external circuit with a steel wire with a diameter of 8 mm. The connection is made from two sides of the object, diametrically opposed to each other. The requirements of the PUE prescribe to protect this tire for reducing by outer wall buildings from corrosion and mechanical damage.

The calculation of the substation grounding device is performed to determine the resistance to the propagation of the system current into the ground.

This value depends on the characteristics of the soil, the dimensions and design of the grounding device, and other factors. The technique is quite voluminous and requires special consideration. But it is worth noting that most often they go from the opposite. Having the required resistance and a certain grade of steel, for example, determine the dimensions of the ground electrode, the number of horizontal electrodes and the depth in a known type of soil.

The grounding devices of substations or overhead lines, as well as the grounding of a power plant, play exclusively important role in their operation. In addition to ensuring the normal operation of these facilities, they ensure the safety of health and life for the people serving them.

TYPICAL TECHNOLOGICAL CHART (TTK)

GROUNDING OF REINFORCED CONCRETE SUPPORTS OF THE POWER SUPPLY LINE VL-10 kV

I. SCOPE

I. SCOPE

1.1. A typical technological map (hereinafter referred to as TTK) is a comprehensive organizational and technological document developed on the basis of methods of scientific organization of labor for performing a technological process and determining the composition production operations using the most modern means mechanization and methods of performing work according to a specific technology. TTK is intended for use in the development of Work Production Projects (PPR), Construction Organization Projects (POS) and other organizational and technological documentation by construction departments. TTC is integral part Projects for the production of works (hereinafter referred to as PPR) and is used as part of the PPR in accordance with MDS 12-81.2007.

1.2. This TTK provides guidance on the organization and technology of work on grounding reinforced concrete poles of an overhead power line VL-10 kV.

The composition of production operations, requirements for quality control and acceptance of work, planned labor intensity of work, labor, production and material resources, measures for industrial safety and labor protection.

1.3. The regulatory framework for the development of a technological map are:

- standard drawings;

- building codes and regulations (SNiP, SN, SP);

- factory instructions and specifications(THAT);

- norms and prices for construction and installation works (GESN-2001 ENiR);

- production norms for the consumption of materials (NPRM);

- local progressive norms and prices, labor costs norms, material and technical resources consumption norms.

1.4. The purpose of creating the TTK is to give a scheme of the technological process recommended by regulatory documents in the production installation work on grounding of reinforced concrete poles of the overhead power line VL-10 kV, in order to ensure their high quality, as well as:

- cost reduction of works;

- reduction of construction time;

- ensuring the safety of work performed;

- organization of rhythmic work;

- rational use of labor resources and machines;

- unification of technological solutions.

1.5. Workers are being developed on the basis of the TTK technological maps(RTK) for the performance of certain types of work (SNiP 3.01.01-85 * "Organization of construction production") for grounding reinforced concrete poles of an overhead power line of 10 kV overhead power lines.

The design features of their implementation are decided in each case by the Working Design. The composition and level of detail of materials developed in the RTC are established by the relevant contracting construction organization, based on the specifics and scope of work performed.

RTK are considered and approved as part of the PPR by the head of the General Contractor Construction Organization.

1.6. TTK can be tied to a specific object and construction conditions. This process consists in clarifying the scope of work, means of mechanization, the need for labor and material and technical resources.

The procedure for linking the TTK to local conditions:

- consideration of map materials and selection of the desired option;

- verification of the compliance of the initial data (volumes of work, time standards, brands and types of mechanisms, building materials used, composition of the worker link) to the accepted option;

- adjustment of the scope of work in accordance with the chosen option for the production of work and a specific design solution;

- recalculation of costing, technical and economic indicators, the need for machines, mechanisms, tools and material and technical resources in relation to the chosen option;

- design of the graphic part with a specific binding of mechanisms, equipment and fixtures in accordance with their actual dimensions.

1.7. A typical flow chart has been developed for engineering and technical workers (foremen, foremen, foremen) and workers performing work in the III temperature zone, in order to familiarize (train) them with the rules for performing work on grounding reinforced concrete poles of the overhead power line VL-10 kV, using the most modern means of mechanization, progressive designs and methods of performing work.

The technological map has been developed for the following scopes of work:

II. GENERAL PROVISIONS

2.1. The technological map has been developed for a set of works on grounding reinforced concrete supports of the overhead power line of the 10 kV overhead line.

2.2. Works on grounding reinforced concrete supports of the overhead power line VL-10 kV are carried out by a mechanized detachment in one shift, the working time during the shift is:

2.3. When grounding reinforced concrete poles of an overhead power line VL-10 kV, the following work is performed:

- grounding of metal structures on reinforced concrete supports;

- arrangement of a ground loop around each support;

- connection of the grounding of the metal structures of the pole with the grounding loop of the pole.

2.4. The technological map provides for the performance of work by an integrated mechanized unit consisting of: portable drilling rig PBU-10 (diameter of the screwed-in electrode 1218 mm, immersion depth h=10.0 m, electrode immersion speed 0.9-2.4 m/min, installation weight m=36 kg); backhoe loader JCB 3CX m (bucket volume g=0.28 m, digging depth=5.46 m); mobile gasoline power station Honda ET12000 (3-phase 380/220 V, N=11 kW, m=150 kg); welding generator (Honda) EVROPOWER EP-200X2 (single station, gasoline, P=200 A, H=230 V, weight m=90 kg); electric Sander PWS 750-125 from Bosch (P=1.9 kg; N=750 W); manual injection gas burner Р2А-01 .

Fig.1. Backhoe loader JCB 3CX m

Fig.2. Power plant ET12000

Fig.3. Injection gas burner Р2А-01

A - burner; b - injection device; 1 - mouthpiece; 2 - mouthpiece nipple; 3 - tip; 4 - tubular mouthpiece; 5 - mixing chamber; 6 - rubber ring; 7 - injector; 8 - union nut; 9 - acetylene valve; 10 - fitting; 11 - union nut; 12 - hose nipple; 13 - tube; 14 - handle; 15 - gland packing; 16 - oxygen valve

Fig.4. Welding generator ER-200X2

Fig.5. Electric grinder PWS 750-125

2.5. The following building materials are used for grounding installation: ground electrodes according to GOST R 50571.5.54-2013; electrodes 4.0 mm E-42 according to GOST 9466-75; loop ram clamps PS-1 according to GOST 5583-78; acetylene dissolved technical , according to GOST 5457-60; grinding wheel, cleaning "Vertex" size 230x6.0x22.0 mm, according to TU 3982-002-00221758-2009, insulating mastic, bitumen-rubber, brand MBR-90 according to GOST 15836-79; primer GT-760 IN according to TU 102-340-83.

Fig.6. Ground electrodes

2.6. Grounding of reinforced concrete poles of the overhead power line VL-10 kV should be carried out in accordance with the requirements of the following regulatory documents:

- SP 48.13330.2011. "Organization of construction. Updated edition of SNiP 12-01-2004";

- STO NOSTROY 2.33.14-2011. Organization of construction production. General provisions;

- STO NOSTROY 2.33.51-2011. Organization of construction production. Preparation and production of construction and installation works;

- SNiP 3.05.06-85. Electrical devices;

- PUE 7th edition "Rules for electrical installations";

- RD 153-34.3-35.125-99. "Guidelines for the protection of electrical networks 6-1150 kV from lightning and internal surges";

- SNiP 12-03-2001. Labor safety in construction. Part 1. General requirements;

- SNiP 12-04-2002. Labor safety in construction. Part 2. Construction production;

- POTR RM 012-2000 .* "Intersectoral Rules for labor protection when working at height";

- VSN 123-90. "Instructions for registration of acceptance documentation for electrical work";

- RD 11-02-2006. Requirements for the composition and procedure for maintaining executive documentation during construction, reconstruction, overhaul capital construction facilities and requirements for certificates of survey of works, structures, sections of engineering and technical support networks;

- RD 11-05-2007. The procedure for maintaining a general and (or) special journal for recording the performance of work during construction, reconstruction, overhaul of capital construction facilities;

- MDS 12-29.2006. "Methodological recommendations for the development and execution of a technological map".

III. ORGANIZATION AND TECHNOLOGY OF WORK PERFORMANCE

3.1. In accordance with SP 48.13330.2001 "Organization of construction. Updated version of SNiP 12-01-2004", prior to the commencement of construction and installation works at the facility, the Contractor is obliged to obtain from the Customer, in the prescribed manner, project documentation and a permit (order) for the performance of construction and installation works . Performing work without a permit (warrant) is prohibited.

3.2. Prior to the start of work on grounding the reinforced concrete poles of the overhead power line of the 10 kV overhead line, it is necessary to carry out a set of organizational and technical measures, including:

- develop a design plan for the construction of CNG filling stations and approve it by the General Contractor and the technical supervision of the Customer;

- solve the main issues related to the material and technical support of construction;

- appoint persons responsible for the safe performance of work, as well as their control and quality of performance;

- provide the site with working documentation approved for the production of work;

- to staff a team of electric linemen, to acquaint them with the project and the technology of work;

- briefing the members of the safety team;

- establish temporary inventory household premises for the storage of building materials, tools, inventory, heating workers, eating, drying and storing work clothes, bathrooms, etc.;

- prepare machines, mechanisms and equipment for the production of work and deliver them to the facility;

- provide workers manual machines, tools and personal protective equipment;

- provide the construction site with fire-fighting equipment and signaling equipment;

- fence the construction site and put up warning signs illuminated at night;

- provide communication for operational and dispatching control of the production of works;

- deliver to the work area necessary materials, fixtures, inventory;

- to install, mount and test construction machines, means of mechanization of work and equipment according to the nomenclature provided by the RTK or PPR;

- draw up an act of readiness of the object for the production of work;

- obtain permission from the technical supervision of the Customer to start work.

3.3. General provisions

3.3.1. To increase the reliability of the operation of power lines, as well as to ensure the safety of maintenance personnel, power line supports must be grounded.

3.3.2. Grounding devices designed for re-grounding, protection against lightning surges must be made on the overhead line supports.

Metal structures and reinforcement of reinforced concrete support elements must be connected to the PEN conductor.

On reinforced concrete poles, the PEN conductor should be connected to the reinforcement of reinforced concrete pillars and struts of the poles.

3.3.3. grounding - deliberate electrical connection of any part (point) of the network, electrical installation or equipment with a grounding device.

Grounding device - a set of grounding conductors and grounding conductors.

grounding conductor - a conductive part or a set of interconnected conductive parts located in electrical contact with earth directly or through an intermediate conductive medium.

Ground conductor - a conductor connecting the grounded part (point) with the ground electrode.

Grounding device resistance - the ratio of the voltage on the grounding device to the current flowing from the grounding conductor into the ground.

3.3.4. When making grounding devices, i.e. when electrically connecting the grounded parts to the ground, they strive to ensure that the resistance of the grounding device is minimal and, of course, not higher than the values ​​​​required by the PUE. A large proportion of the grounding resistance falls on the transition from the ground electrode to the ground. Therefore, in general, the resistance of the grounding device depends on the quality and condition of the soil itself, the depth of the ground electrodes, their type, quantity and relative position.

3.3.5. Grounding conductors are metal conductors laid in the ground. Grounding switches can be made in the form of vertically hammered rods, pipes or angles, interconnected by horizontal conductors made of round or flat steel in the grounding center. The length of vertical grounding conductors is usually 2.5-3.0 m. Horizontal grounding conductors and the top of vertical grounding conductors must be at a depth of at least 0.5 m, and on arable land - at a depth of 1 m. Grounding conductors are interconnected by welding.

3.3.6. All types of grounding significantly reduce the magnitude of atmospheric and internal overvoltages on power lines. However, in some cases, these protective groundings are not enough to protect the insulation of power lines and electrical appliances from overvoltages. Therefore, additional devices are installed on the lines, which include protective spark gaps, tubular and valve arresters.

3.3.7. To determine the technical condition of the grounding device in accordance with the standards for testing electrical equipment, the following must be carried out:

- measurement of resistance of the grounding device (table 1);

- measurement of contact voltage (in electrical installations, the grounding device of which is made according to the norms for touch voltage), checking the presence of a circuit between the grounding device and the grounded elements, as well as the connections of natural grounding conductors with the grounding device;

- measurement of short-circuit currents of the electrical installation, checking the condition of the breakdown fuses;

- measurement of soil resistivity in the area of ​​the grounding device.

The measurement results are documented in protocols.

The highest allowable resistance values ​​of grounding devices

Table 1

3.4. Preparatory work

3.4.1. Work on the installation of grounding can be started after checking the complete readiness of the power supply line.

3.4.2. The readiness of the VL-10 kV line for grounding installation is determined by the foreman or foreman. Defects or unfinished work discovered during the inspection of the power line route in kind must be included in the defective statement. It is allowed to proceed with the installation of grounding only after eliminating the defects and imperfections indicated in the statement, and obtaining written permission from the person responsible for the installation of the 10 kV overhead line.

3.4.3. After inspecting the route and obtaining a work permit for installation, they begin to prepare for the installation of grounding, which consists in:

- preparation of electrodes (ground electrodes);

- preparation of grounding conductors.

3.4.4. Electrodes (ground electrodes) are prepared in the workshops of electrical workpieces for vertical driving. For the manufacture of the ground electrode, angle steel, substandard and undersized pipes, and round steel are used. For grounding devices, mainly vertical electrodes made of steel rods or angles are used. Round electrodes are the most economical and durable. Their diameter is taken depending on the density of the soil and the depth of immersion: up to 4 m - the diameter of the electrode is 10-12 mm, up to 5 m - 12-14 mm. In soils where aggressive groundwater can cause increased metal corrosion, galvanized or copper-plated ground electrodes are used. Electrodes from steel angles 40x40x4 mm are made 2.5-3.0 m long with one pointed end for better penetration into the ground.

3.4.5. The tip produced by the industry (Fig. 1), * is a steel strip 16 mm wide, pointed at the end and bent along a helical line. The weight of the tip 48 mm long and 16 mm in diameter is 0.03 kg. In the absence of standard tips and the need to prepare them manually, it is easiest to forge the end of the electrode, bringing its diameter to about 1.5 electrode diameters, and sharpen the end (Fig. 1, b). Such an electrode is relatively cheap and sinks much more easily than an electrode whose end is tapered without broadening. The use of the latter is less rational, since it is not always possible to screw it in to a depth of 5 m. Electrodes, to which a spiral of wire 4-6 mm in diameter and about 1 m long is welded near the pointed end (Fig. 1, c), forming a tip in the form a drill, or a cut and bent steel washer welded on (Fig. 1, d), is screwed in easily. With their help, you can even screw the electrode into the frozen ground at a small freezing depth. In the manufacture of electrodes with a spiral, it is necessary to take into account the direction of rotation of the used submersible, since in some designs of electric submersibles with a gearbox, the rotation is left-handed, and the helical electrode must correspond to this, otherwise the electrode will be braked together with screwing.

________________

* The numbering of the figures corresponds to the original. - Database manufacturer's note.

Fig.7. Rod electrodes prepared for immersion:

A - the tip is made of a steel strip bent along a helical line and welded to the electrode: b - the lower end of the electrode is broadened by forging and pointed; c - a steel wire is welded onto the pointed end of the electrode, giving the electrode the property of a drill; g - tip with a curved and welded steel washer

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Overhead line > Grounding devices of overhead lines

GROUNDING DEVICES FOR OVERHEAD POWER TRANSMISSION LINES WITH VOLTAGE
0.38; 6; 10; 20 kV
this section has been prepared according to the standard design SERIES 3.407-150

Typical designs of this series are developed taking into account the requirements of the Electrical Installation Rules (PUE) of the sixth edition, both in terms of design and in terms of taking into account the normalized resistance to the spreading of ground electrodes for soils with equivalent resistivity up to 100 .
The series includes designs of ground electrodes intended for grounding poles, as well as poles with equipment installed on them on 0.38, 6, 10, 20 kV overhead lines in accordance with the requirements of chapter 1.7 and other chapters of the PUE.
The following designs of earth electrodes are provided: vertical, horizontal (beam), vertical in combination with horizontal, closed horizontal (loop), contour in combination with vertical and horizontal (beam).
Structural implementation of grounding and zero protective conductors, laid on the supports of overhead lines, are accepted in accordance with the current standard projects and projects for the reuse of overhead lines.

The designs of this series should be used by designers, installers and operators during the construction and reconstruction of 0.38, 6, 10 and 20 kV overhead lines.
This series does not consider grounding conductors in areas of the northern construction and climatic zone (sub-areas IA, IB, IG and ID according to SIiP 2.01.01-82) and in areas where rocky soils are distributed.

GENERAL PROVISIONS FOR THE CALCULATION OF GROUNDING
The initial data in the design of grounding devices for overhead lines are the parameters of the electrical structure of the earth and the requirements for ground resistance values.
Soil resistivity r and the thickness of soil layers with different values ​​of r can be obtained directly from measurements along the route of the designed overhead line or from measurements of the resistivity of similar soils in the area of ​​the overhead line route, at substation sites, etc.
In the absence of data from direct measurements of soil resistivity, designers should use the geological section of soil along the route received from surveyors and generalized values ​​of soil resistivity various soils given in the table.

Generalized values ​​of soil resistivity

At present, sufficiently reliable engineering methods have been developed for determining the electrical structure of the earth, calculating the resistance of grounding conductors in a homogeneous and two-layer earth, as well as methods for bringing real multilayer electrical structures of the earth to calculated two-layer equivalent models. The developed methods make it possible to determine the appropriate designs of artificial ground electrodes for a given electrical structure of the soil, providing a normalized value of the resistance of the ground conductors.

CHOICE OF SECTION OF EARTHING ELEMENTS
On the basis of studies conducted by SIBNIIE, it was found that the spreading resistance is practically independent of the size and configuration of the cross-section of the ground electrode. At the same time, earth electrode elements with a circular cross section are much more durable than flat conductors equivalent in cross section, because at the same corrosion rate, the remaining cross section of the latter decreases much faster. In this regard, it is advisable to use only round steel for grounding overhead lines.

STRUCTURAL PERFORMANCE OF EARTHINGS AND RECOMMENDATIONS FOR INSTALLATION
VL grounding switches are provided from round steel: horizontal with a diameter of 10 mm, vertical - 12 mm, which is quite enough for the estimated service life in conditions of weak and medium corrosion.
In the case of increased corrosion, measures should be taken to increase the durability of the ground electrodes.
Angular steel and steel pipes. At the same time, their dimensions must comply with the requirements of the PUE.
Given that the maximum depth of immersion of vertical ground electrodes (electrodes) with currently existing mechanisms in fairly soft soils is 20 m, in this series they are provided with a length of 3, 5, 10, 15 and 20 m.
In soils with low resistivity (at up to 10 ohm h m) provides for the use of only the lower ground outlet - a rod electrode with a length of about 2 m, supplied complete with a reinforced concrete rack.
When installing earthing switches, the requirements of building codes and regulations and GOST 12.1.030-81 should be observed.
For the development of trenches when laying horizontal grounding, it is possible to use an ETTs-161 excavator based on the Belarus MTZ-50 tractor. They can also be laid using a mounting plow. At the same time, it is necessary to take into account the need to dig pits measuring 80x80x60 cm in places where vertical earth electrodes are immersed and their subsequent connection by welding to a horizontal earth electrode.
Vertical earthing switches are immersed by vibrating or drilling, as well as by driving or laying in finished wells.
Immersion of vertical electrodes is carried out in such a way that their top is 20 cm higher than the bottom of the trenches.
Then horizontal grounding conductors are laid. The ends of the vertical grounding conductors are bent at the places where they adjoin the horizontal grounding conductor in the direction of the trench axis.
The connection of grounding conductors between soda should be carried out by overlap welding. In this case, the length of the overlap should be equal to six diameters of the ground electrode. Welding should be carried out around the entire perimeter of the overlap. Grounding connection nodes are given in sections ES37 and ES38.
To protect against corrosion, prefabricated joints should be coated with bituminous varnish.
Backfilling of trenches is carried out by a bulldozer based on the Belarus MTZ-50 tractor.
Section ES42 shows the volumes earthworks in the case of digging trenches with mechanized and manual digging.
When implementing an overhead line project, in particular, grounding conductors, it is necessary to take into account the capabilities of the mechanical column that will build this line in terms of equipping it with mechanisms.
After the installation of grounding conductors, control measurements of their resistance are made. If the resistance exceeds the rated value, vertical grounding conductors are added to obtain the required resistance value.

CONNECTING EARTHINGS TO SUPPORTS
The connection of grounding switches to special grounding outlets (details) of reinforced concrete poles and grounding slopes of wooden poles can be either welded or bolted. Contact connections must comply with class 2 according to GOST 10434-82.
At the point of connection of ground electrodes to grounding slopes on wooden poles of 0.38 kV overhead lines, additional pieces of round steel with a diameter of 10 mm are provided, and grounding slopes on wooden poles of 6, 10 and 20 kV overhead lines made of round steel with a diameter of at least 10 mm are connected directly to the earth conductor.
The presence of a bolted connection of the grounding descent with the ground electrode makes it possible to control the grounding devices of the overhead line supports without climbing onto the support and disconnecting the line.
If there are devices for monitoring grounding conductors, the connection of the grounding descent with the grounding conductor can be made permanent.
Control and measurements of grounding conductors must be carried out in accordance with the "Rules for the technical operation of power plants and networks".

DESIGN RECOMMENDATIONS
Due to the fact that engineering methods for calculating ground electrodes have been developed for a two-layer soil structure, the calculated multilayer electrical structure soil is reduced to an equivalent two-layer structure. The reduction method depends on the nature of the change in the resistivity of the layers of the design structure in depth and the depth of the ground electrode.
In a homogeneous soil and in a soil with a specific resistance decreasing in depth (of the order of 3 or more times), vertical ground electrodes are the most appropriate.
If the underlying soil layers have significantly higher resistivity values ​​than the upper ones, or when the immersion of vertical ground electrodes is difficult or impossible due to the density of the soil, it is recommended to use horizontal (beam) ground electrodes as artificial ground electrodes.
If vertical ground electrodes do not provide normalized resistance values, then horizontal ones are laid in addition to the vertical ones, i.e. combined ground electrodes are used.
Based on the equivalent two-layer structure and pre-selected earth electrode design,.
For foundand for the normalized resistance of the grounding device according to the PUE, the appropriate type of grounding conductor of this series is selected.
Below is a table for the selection of drawings of grounding conductors.
Calculations of grounding conductors are made on a computer according to the program developed by the West Siberian branch of the Institute "Selenergoproekt".

Attention: according to PUE 7th ed. grounding conductors for repeated groundings PEN - the conductor must havedimensions not less than those given in table. 1.7.4.