Outdoor lighting in cities and villages plays a very important role important role. This is a way for every resident, both a metropolis and a small settlement, to feel comfortable. This is an indicator of safety and responsible attitude towards the place where people live. Lighting can be installed centrally by city authorities or by residents independently (near their home). However, when creating outdoor lighting throughout the city, grounding of overhead power poles plays an important role.

When creating grounding, you must be guided regulatory documentation, approved at the official level. This is especially true for grounding overhead lines (OHL). We will talk to you now about all the subtleties and nuances of this procedure.

Why is grounding of overhead lines necessary?

Installation of grounding on overhead lines is necessary to ensure the safety of people. If the insulation of the lines is broken, the current can pass into the soil and spread throughout the territory. The soil does not stop the current from spreading. Thus, every resident may be exposed to electric shock.

Grounding of overhead power poles prevents propagation electric potential and reducing the step voltage on the ground surface. Therefore, if a person touches the support, he will not receive an electric shock. The grounding performance of overhead lines depends on the resistance of the soil.

Types of grounding

The installation of grounding on overhead lines is formed based on the type of support structure itself. It can be of 3 types:

Reinforced concrete. It is necessary to have neutral grounding, fittings, and a connection to a grounded wire of a special conductor. The conductor must be at least 6 mm in diameter.

Wooden. To ground wooden supports increased requirements apply. It can only take place in those settlements where the height of buildings does not exceed 2 floors. Also pipes in locality should not have a height of more than 10-15 meters. The presence of trees is possible, but if they are not in close proximity to the object. In this case, the hooks and pins do not require grounding. Also, grounding of supports requires protection against atmospheric surge voltage. Most often, grounding of wooden poles is installed in areas where there are no residential buildings or large concentrations of people.

Metal. This is the most common type of support. In recent years, it has been in maximum demand. Steel supports have become more popular than reinforced concrete and wooden ones, although in essence they are similar to reinforced concrete supports. Grounding of 10 kV overhead line supports, 20 and 35 kV requires taking into account the distance between adjacent supports. The average distance between supports is from one hundred to two hundred meters. The exact distance is determined by hydrometeorology, based on the number of thunderstorms that occur per year in the territory. The initial data is taken as the average value over several recent years. A mandatory procedure for grounding supports that have branches to structures and areas where people live.

Types of ground electrodes

In order to protect power lines from overvoltage, two types of grounding conductors are used:

Vertical. The pins are mounted vertically into the ground.

Horizontal. Special plates are used. They are indispensable when working on rocky soils.

The type of ground electrode used is determined by the type of soil or the degree of outdoor lighting.

How to install grounding conductors

Installation of grounding on overhead lines (primary or repeated) is carried out as follows:

From the beginning of the supports, the ground is measured. After this, a trench is created, the width of which is 0.5 meters and the depth of 1 meter.

The exact length of the trench is indicated in the officially approved project. The number of required grounding conductors is also indicated there.

Grounding conductors are immersed in the trench and a circuit is formed.

Welding is in progress.

The joints formed during the welding process are protected from corrosion.

A grounding drain is installed.

Official documentation

PUE is documentation that regulates the basic principles of grounding installation. It is necessary to focus on this information when implementing protective measures.

The PUE contains information about:

Installation of grounding on each support;

Installing grounding on parts of the support.

Features of installing grounding on overhead lines

Installation of grounding on overhead lines up to 1 kV requires taking into account the following standards:/p>

A network with a grounded neutral must have a jumper made of an insulated conductor./p>

Before use, contact connections are thoroughly cleaned and coated with Vaseline.

The resistance of the structures should not be higher than 50 Ohms.

Grounding of overhead power poles for outdoor lighting with cable power supply is carried out through the cable sheath.

Conclusion

Installation of grounding on overhead lines requires mandatory compliance with the rules and regulations set out in the PUE. This is the only way to produce high-quality reliable operation, which will provide protection to the supports and prevent possible risk situations when people may be shocked at the moment of contact with the support.

Exception information: I-1-88

Action ended 01/01/1988

Front page

List of drawings

Explanatory note

Wooden supports for 0.4 kV overhead lines. Hook Grounding and Rotary Grounding neutral wire

Wooden supports for 35 kV overhead lines. Grounding the cable on intermediate and anchor supports

Wooden supports for overhead lines 6 - 10 kV. Installation of protective gaps on supports when crossing with overhead lines or communication lines

Wooden supports for 20 kV overhead lines. Installation of protective gaps on supports when crossing with overhead lines or communication lines

Wooden supports for 35 kV overhead lines. Installation of protective gaps on supports when crossing with overhead lines or communication lines

Wooden supports for overhead lines 6 - 10 kV. Grounding of tubular arresters RT-6 and RT-10 on anchor and intermediate supports

Wooden supports for overhead lines 6 - 10 kV. Grounding of tubular arresters RT-6 and RT-10 (transitional) on an elevated anchor support

Wooden supports for overhead lines 6 - 10 kV. Grounding the cable sleeve and tubular arresters at the end support

Wooden supports for 20 kV overhead lines (transitional). Grounding of RT-20 tubular arresters on an intermediate elevated support

Wooden supports for 20 kV overhead lines (transitional). Grounding of RT-20 tubular arresters on an elevated anchor support

Wooden supports for 35 kV overhead lines. Grounding of RT-35 tubular arresters on an anchor support

Reinforced concrete supports of 0.4 kV overhead lines. Grounding of intermediate OP-0.4 and intermediate cross PK-0.4 supports

Reinforced concrete supports of 0.4 kV overhead lines. Grounding of intermediate transition support PP-0.4

Reinforced concrete supports of 0.4 kV overhead lines. Grounding of corner anchor supports UA-I-0.4 and UA-II-0.4

Reinforced concrete supports of 0.4 kV overhead lines. Grounding of end K-0.4 and anchor A-0.4 supports

Reinforced concrete supports of 0.4 kV overhead lines. Grounding of branch anchor support OA-0.4

Reinforced concrete supports for 0.4 kV overhead lines. Grounding of branch transition support OP-0.4

Reinforced concrete supports of 0.4 kV overhead lines. Grounding of inlet boxes on intermediate and end supports for connecting electric motors of mobile machines

Reinforced concrete supports of 0.4 kV overhead lines. Grounding a box with AP50-T for sectioning the main line on an anchor support

Reinforced concrete supports of 0.4 kV overhead lines. Grounding of a 4 km cable coupling, RVN-0.5 arresters, SPO-200 lamp on the end support

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of intermediate supports for uninhabited and populated areas P10-1B; P20-1B; P10-2B; P20-2B

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of corner intermediate supports for uninhabited and populated areas UP10-1B; UP20-1B

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of end supports for uninhabited and populated areas K10-1B; K10-2B; K20-1B

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of branch intermediate supports for uninhabited areas OP10-1B; OP20-1B; OP10-2B; OP20-2B

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of branch supports for uninhabited areas OP10-1B; OP10-2B and 020-1B

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of branch corner intermediate supports for uninhabited areas OUP10-1B; OUP20-1B

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of the KMA(KMCh) cable coupling and RT-6 arresters; RT-10 on end support

Reinforced concrete supports of overhead lines 6 - 10 and 20 kV. Grounding of the end supports of 6 - 10 and 20 kV overhead lines with disconnectors for populated and uninhabited areas KR10-1B; KR10-2B; KR10-3B; KR20-1B

Reinforced concrete supports of 35 kV overhead lines. Grounding of intermediate supports for uninhabited and populated areas P35-1B and P35-2B

Reinforced concrete supports of 35 kV overhead lines. Grounding of intermediate supports with a cable for uninhabited and populated areas PT35-1B and PT35-2B

Reinforced concrete supports of 35 kV overhead lines. Grounding of corner anchor supports for uninhabited and populated areas UA35-16; UA35-26

Reinforced concrete supports of 35 kV overhead lines. Grounding of a corner intermediate support for uninhabited areas UP35-1B

Reinforced concrete supports of 35 kV overhead lines. Grounding of end and anchor supports for uninhabited and populated areas K35-1B; K35-2B; A35-1B; A35-2B

Reinforced concrete supports of 35 kV overhead lines. Grounding of angular intermediate, end and anchor supports with a cable for uninhabited and populated areas UPT35-1B; KT35-1B; KT35-2B; AT35-1B; AT35-2B

Reinforced concrete supports of 35 kV overhead lines. Grounding of corner anchor supports with a cable for uninhabited and populated areas UAT35-1B; UAT35-2B

Reinforced concrete supports VL 10; 20; 35 kV. Grounding of the transitional intermediate support PP35-B; PP20-B; PP10-B

Reinforced concrete supports of 35 kV overhead lines. Grounding of an intermediate transition support with a PPT35-B cable

Reinforced concrete supports VL 10; 20; 35 kV. Grounding of the corner anchor transition support UAP35-B; UAP20-B; UAP10-B

Reinforced concrete supports of 135 kV overhead line. Grounding of the corner anchor transition support UAPT35-B

Reinforced concrete supports VL 10; 20; 35 kV. Grounding of the end transition support KP35-B; KP20-B; KP10-B

Reinforced concrete supports of 35 kV overhead lines. Grounding of the end transition support with cable KPT35-B

Disconnection point 20 kV with an automatic sectional separator on a reinforced concrete support. Grounding

Examples of re-grounding the neutral wire, hooks and pins on reinforced concrete and wooden supports

Sketches of grounding conductors for R =<10 ом

Sketches of grounding conductors for R =<15 ом; R = < 20 ом

Sketches of grounding conductors for R =< 30 ом

Formulas for determining the resistance to current spreading of various ground electrodes

Initial data for calculating grounding conductors

Reinforced concrete and wooden supports. Grounding of supports. Clamp selection

Wooden supports for 0.4 kV overhead lines. Grounding of hooks and rotary grounding of the neutral wire. Knots. Details

Units and parts

Examples of grounding devices. Nodes

This document is located in:

Organizations:

15.06.1971	Approved		245
	Designed by

GROUNDING DEVICES FOR OVERHEAD POWER LINE SUPPORTS

0.38; 6; 10; 20 kV

This section has been prepared in accordance with the standard design SERIES 3.407-150

The standard designs of this series are developed taking into account the requirements of the Rules for the Construction of Electrical Installations (PUE) of the sixth edition, both in terms of design and in terms of taking into account the standardized resistance to spreading of grounding conductors for soils with an equivalent resistivity of up to 100.

The series includes designs of grounding conductors intended for grounding poles, as well as poles with equipment installed on them on overhead lines of 0.38, 6, 10, 20 kV in accordance with the requirements of Chapter 1.7 and other chapters of the PUE.

The following designs of ground electrodes are provided: vertical, horizontal (radial), vertical in combination with horizontal, closed horizontal (circuit), circuit in combination with vertical and horizontal (radial).

The design of grounding and neutral protective conductors laid on overhead line supports is adopted in accordance with current standard designs and projects for the reuse of overhead line supports.

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 systems in areas of the northern construction-climatic zone (subdistricts IA, IB, IG and ID according to SIiP 2.01.01-82) and in areas of rocky soils.

GENERAL PROVISIONS FOR CALCULATION OF GROUNDING ELECTRICES

The initial data when designing grounding devices for overhead lines are the parameters of the electrical structure of the earth and the requirements for grounding resistance values.

The resistivity of soils 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 direct measurements of soil resistivity, designers should use the geological section of the soil along the route received from surveyors and the generalized values ​​of the resistivity of various soils given in the table.

Generalized values ​​of soil resistivity

Currently, fairly reliable engineering methods have been developed for determining the electrical structure of the earth, calculating the resistance of grounding conductors in 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 appropriate designs of artificial grounding electrodes for a given electrical structure of the soil, providing a standardized value of the resistance of the grounding electrodes.

SELECTION OF THE SECTION OF GROUNDING ELEMENTS

Based on studies carried out by SIBNIIE, it has been established that the spreading resistance is practically independent of the size and configuration of the cross-section of the ground electrode. At the same time, grounding elements having a circular cross-section are much more durable than flat conductors of equivalent 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 overhead line grounding conductors.

CONSTRUCTION OF EARTHING ELECTRICES AND INSTALLATION RECOMMENDATIONS

The overhead line grounding switches are made of round steel: horizontal with a diameter of 10 mm, vertical with a diameter of 12 mm, which is quite sufficient for the design service life under conditions of mild and moderate corrosion.

In case of increased corrosion, measures must be taken to increase the durability of grounding conductors.

Angle steel and steel pipes can also be used as vertical grounding conductors. At the same time, their dimensions must comply with the requirements of the PUE.

Considering that the maximum immersion depth of vertical grounding conductors (electrodes) with currently existing mechanisms in fairly soft soils is 20 m, in this series they are provided in lengths of 3, 5, 10, 15 and 20 m.

In soils with low resistivities (up to 10 OhmHm), it is envisaged to use only the lower grounding outlet - a rod electrode about 2 m long, supplied complete with a reinforced concrete stand.

When installing grounding conductors, the requirements of building codes and regulations and GOST 12.1.030-81 must be observed.

To develop trenches when laying horizontal grounding conductors, it is possible to use an ETC-161 type excavator based on the Belarus MTZ-50 tractor. They can also be laid using a mounting plow. In this case, one should take into account the need to dig pits measuring 80x80x60 cm in places where vertical grounding conductors are immersed and their subsequent connection by welding to a horizontal grounding conductor.

Vertical grounding rods are immersed by vibration or drilling, as well as by driving or backfilling into finished wells.

The vertical electrodes are immersed so that their top is 20 cm above the bottom of the trenches.

Then horizontal grounding conductors are laid. The ends of the vertical grounding conductors are bent at the points where they adjoin the horizontal grounding conductor in the direction of the trench axis.

The connection of grounding conductors between soda should be performed by lap welding. In this case, the length of the overlap should be equal to six diameters of the ground electrode. Welding should be performed along 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 bitumen varnish.

The trenches are filled with a bulldozer based on the Belarus MTZ-50 tractor.

Section ES42 shows the volume of excavation work in the case of digging trenches using 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 standardized value, vertical grounding conductors are added to obtain the required resistance value.

CONNECTING GROUNDING LEADERS TO SUPPORTS

The connection of grounding conductors to special grounding outlets (parts) of reinforced concrete pillars and grounding outlets of wooden supports can be either welded or bolted. Contact connections must comply with class 2 according to GOST 10434-82.

At the point where the grounding conductors are connected to the grounding slopes on the wooden supports of the 0.38 kV overhead line, additional sections of round steel with a diameter of 10 mm are provided, and the grounding slopes on the wooden supports of the 6, 10 and 20 kV overhead lines, made of round steel with a diameter of at least 10 mm, are connected directly to the ground electrode.

The presence of a bolted connection between the grounding descent and the ground electrode makes it possible to monitor the grounding devices of overhead line supports without lifting onto the support and disconnecting the line.

If there are devices for monitoring grounding conductors, the connection of the grounding drain to the grounding conductor can be made permanent.

Monitoring and measurements of grounding conductors must be carried out in accordance with the “Rules for the technical operation of power plants and networks”.

Due to the fact that engineering methods for calculating grounding conductors are developed for a two-layer soil structure, the calculated multi-layer electrical structure of the 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 along the depth and the depth of the ground electrode.

In homogeneous soil and in soil with decreasing resistivity with depth (about 3 times or more), vertical grounding conductors are the most appropriate.

If the underlying soil layers have significantly higher resistivity values ​​than the upper ones, or when the immersion of vertical grounding conductors is difficult or impossible due to the density of the soil, it is recommended to use horizontal (beam) grounding conductors as artificial grounding conductors.

If vertical grounding conductors do not provide standardized resistance values, then horizontal ones are installed in addition to the vertical ones, i.e. combined grounding conductors are used.

Based on the equivalent two-layer structure and the pre-selected ground electrode design, it is determined.

For the found and normalized resistance of the grounding device according to the PUE, the appropriate type of ground electrode of this series is selected.

Below is a table for selecting drawings of grounding conductors.

Calculations of grounding conductors were performed on a computer using a program developed by the West Siberian branch of the Selenergoproekt Institute.

Attention: according to the PUE 7th ed. grounding conductors for repeated grounding of the PEN conductor must have dimensions no less than those given in table. 1.7.4.

Table 1.7.4. The smallest dimensions of grounding conductors and grounding conductors laid in the ground

Selection table for grounding electrode drawings

TYPICAL TECHNOLOGICAL CARD (TTK)

GROUNDING OF REINFORCED CONCRETE SUPPORTS OF POWER SUPPLY LINES OHL-10 kV

I. SCOPE OF APPLICATION

I. SCOPE OF APPLICATION

1.1. A standard technological map (hereinafter referred to as TTK) is a complex organizational and technological document developed on the basis of methods of scientific organization of labor for performing a technological process and defining the composition of production operations using the most modern means of mechanization and methods of performing work using a specific technology. TTK is intended for use in the development of Work Performance Projects (WPP), Construction Organization Projects (COP) and other organizational and technological documentation by construction departments. The TTK is an integral part of the Work Performance Projects (hereinafter referred to as the WPR) and is used as part of the WPR in accordance with MDS 12-81.2007.

1.2. This TTK provides instructions on the organization and technology of work on grounding reinforced concrete supports of the overhead power supply line of 10 kV overhead power lines.

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

1.3. The regulatory basis for the development of a technological map is:

- standard drawings;

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

- factory instructions and technical conditions (TU);

- standards and prices for construction and installation work (GESN-2001 ENiR);

- production standards for material consumption (NPRM);

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

1.4. The purpose of creating the TTK is to provide a technological process diagram recommended by regulatory documents for installation work on grounding reinforced concrete supports of the 10 kV overhead power supply line, in order to ensure their high quality, as well as:

- reducing the cost of work;

- reduction of construction duration;

- ensuring the safety of work performed;

- organizing rhythmic work;

- rational use of labor resources and machines;

- unification of technological solutions.

1.5. On the basis of the TTK, Working Technological Maps (RTK) are being developed for the implementation of certain types of work (SNiP 3.01.01-85 * "Organization of construction production") for grounding reinforced concrete supports of the overhead power supply line 10 kV.

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

The RTK is reviewed and approved as part of the PPR by the head of the General Contracting Construction Organization.

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

The procedure for linking the TTC to local conditions:

- reviewing map materials and selecting the desired option;

- checking the compliance of the initial data (amount of work, time standards, brands and types of mechanisms, building materials used, composition of the worker group) with 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 calculations, technical and economic indicators, requirements for machines, mechanisms, tools and material and technical resources in relation to the chosen option;

- design of the graphic part with specific reference to mechanisms, equipment and devices in accordance with their actual dimensions.

1.7. A standard flow chart has been developed for engineering and technical workers (work managers, foremen, foremen) and workers performing work in the third temperature zone, in order to familiarize (train) them with the rules for carrying out work on grounding reinforced concrete supports of the overhead power supply 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 scope of work:

Length of 10 kV overhead power supply line	- 260 m;
Reinforced concrete supports	- 7 pcs.

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 supply line of 10 kV overhead power lines.

2.2. Work on grounding reinforced concrete supports of the overhead power supply line of 10 kV overhead power lines is carried out by a mechanized team in one shift, the duration of working hours during the shift is:

2.3. When grounding reinforced concrete supports of a 10 kV overhead power supply line, perform the following work:

- grounding of metal structures on reinforced concrete supports;

- arrangement of a grounding loop around each support;

- connection of the grounding of the metal structures of the support with the grounding circuit of the support.

2.4. The technological map provides for the work to be carried out by a complex mechanized unit consisting of: portable drilling rig PBU-10 (diameter of 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); JCB 3CX m backhoe loader (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-200Х2 (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 P2A-01 .

Fig.1. JCB 3CX m backhoe loader

Fig.2. Power station ET12000

Fig.3. Injector gas burner P2A-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 - stuffing box; 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: grounding electrodes according to GOST R 50571.5.54-2013; electrodes 4.0 mm E-42 according to GOST 9466-75; loop die clamps PS-1 according to GOST 5583-78; acetylene dissolved technical , according to GOST 5457-60; grinding wheel, cleaning wheel "Vertex" size 230x6.0x22.0 mm, according to TU 3982-002-00221758-2009, insulating mastic, bitumen-rubber, grade MBR-90 according to GOST 15836-79; primer GT-760 IN according to TU 102-340-83.

Fig.6. Grounding electrodes

2.6. Work on grounding reinforced concrete supports of the 10 kV overhead power supply line should be carried out in accordance with the requirements of the following regulatory documents:

- SP 48.13330.2011. "Construction organization. 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 execution 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. "Guide to the protection of electrical networks 6-1150 kV from lightning and internal overvoltages";

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

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

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

- VSN 123-90. "Instructions for preparing acceptance documentation for electrical installation work";

- RD 11-02-2006. Requirements for the composition and procedure for maintaining as-built documentation during construction, reconstruction, major repairs of capital construction projects and requirements for inspection reports of work, structures, sections of engineering support networks;

- RD 11-05-2007. The procedure for maintaining a general and (or) special log of work performed during construction, reconstruction, major repairs of capital construction projects;

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

III. ORGANIZATION AND TECHNOLOGY OF WORK EXECUTION

3.1. In accordance with SP 48.13330.2001 "Organization of construction. Updated version of SNiP 12-01-2004" before the start of construction and installation work at the site, the Contractor is obliged to obtain from the Customer in the prescribed manner design documentation and a permit (order) to perform construction and installation work . Carrying out work without permission (warrant) is prohibited.

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

- develop a work plan for the construction of a CNG filling station and have it agreed upon by the General Contractor and the Customer’s technical supervision;

- resolve the main issues related to the logistics of construction;

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

- provide the site with working documentation approved for work;

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

- conduct safety training for team members;

- install temporary inventory household premises for storing building materials, tools, equipment, heating workers, eating, drying and storing work clothes, bathrooms, etc.;

- prepare machines, mechanisms and equipment for work and deliver them to the site;

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

- provide the construction site with fire-fighting equipment and alarm systems;

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

- provide communication for operational dispatch control of work;

- deliver the necessary materials, devices, equipment to the work area;

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

- draw up an act of readiness of the facility for work;

- obtain permission from the Customer’s technical supervision to begin 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 operating personnel, power line supports must be grounded.

3.3.2. The overhead line supports must be equipped with grounding devices designed for re-grounding and protection against lightning surges.

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

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

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

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

Ground electrode - a conductive part or a set of interconnected conductive parts that are in electrical contact with the ground directly or through an intermediate conductive medium.

Grounding conductor - a conductor connecting the grounded part (point) to the ground electrode.

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

3.3.4. When making grounding arrangements, 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 occurs at 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 electrodes are metal conductors laid in the ground. Grounding electrodes can be made in the form of vertically driven rods, pipes or angles connected to each other by horizontal conductors made of round or strip steel into a grounding source. 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 connected to each other 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 equipment 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 electrical equipment testing standards, the following must be carried out:

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

- measuring touch voltage (in electrical installations, the grounding device of which is made according to touch voltage standards), 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;

- measuring short-circuit currents of electrical installations, checking the condition of breakdown fuses;

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

The measurement results are documented in protocols.

The highest permissible resistance values ​​of grounding devices

Table 1

	Installation characteristics	Allowable resistance value, Ohm
	Installations with voltage up to 1000 V:
	generators and transformers with power up to 1000 kVA
	other equipment
	Installations with voltages above 1000 V:
	installation with ground fault currents exceeding 500 A
	installation with ground fault currents less than 500 A
	the same in the case of using a grounding device simultaneously for installations with voltages up to 1000 V
	Grounding conductor of a free-standing lightning rod in electrical installations with voltages above 1000 V
	Each of the repeated groundings of the neutral wire of electrical installations with voltages up to 1000 V with solid grounding of the neutral
	Grounding device of metal and reinforced concrete supports of overhead power lines:
	voltage above 1000 V with earth resistivity, Ohm cm:
	5x104-10x104
	more than 10x104
	voltage up to 1000 V with insulated neutral**
	Grounding switch for tubular arresters:
	installed at the intersection of 20 kV lines and in places with weakened insulation
	installed at the approaches to lines and substations, the tires of which are electrically connected to rotating machines
where I is the calculated ground fault current, A. * In networks for which the resistance of the grounding devices of generators and transformers is 10 Ohms, the resistance of the grounding devices of each of the repeated groundings should be no more than 30 Ohms, with at least three of them. ** In networks with a grounded neutral, metal supports and fittings must be connected to a neutral grounded wire.

3.4. Preparatory work

3.4.1. Grounding installation work can begin after checking the complete readiness of the power supply line.

3.4.2. The readiness of the 10 kV overhead line for grounding installation is determined by the foreman or foreman. Defects or unfinished work discovered during an inspection of the power line route in situ must be included in the defect list. It is allowed to proceed with the installation of grounding only after eliminating the defects and deficiencies 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 receiving an installation permit, they begin preparing for the installation of grounding, which consists of:

- preparation of electrodes (grounding conductors);

- preparation of grounding conductors.

3.4.4. Electrodes (grounding conductors) are prepared in electrical installation workshops for vertical driving. For the manufacture of ground electrodes, angle steel, substandard and undersized pipes, and round steel are used. For grounding devices, predominantly 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 - electrode diameter 10-12 mm, up to 5 m - 12-14 mm. In soils where increased corrosion of metal can be caused by aggressive groundwater, galvanized or copper-plated grounding conductors are used. Electrodes from steel corners 40x40x4 mm are made 2.5-3.0 m long with one pointed end for better penetration into the ground.

3.4.5. The commercially produced tip (Fig. 1),* is a steel strip 16 mm wide, pointed at the end and bent along a helical line. The mass of a tip with a length of 48 and a diameter of 16 mm is 0.03 kg. In the absence of standard tips and the need to prepare them manually, the easiest way is to forge the end of the electrode, bringing its diameter to approximately 1.5 times the diameter of the electrode, and sharpen the end (Fig. 1, b). Such an electrode is relatively cheap and immerses much easier than an electrode whose end is pointed into a cone without widening. The use of the latter is less rational, since it is not always possible to screw it to a depth of 5 m. Electrodes to which a spiral of wire with a diameter of 4-6 mm and a length of about 1 m is welded near the pointed end (Fig. 1, c), forming a tip in the form a drill, or a cut and bent steel washer is welded (Fig. 1, d), screwed in easily. With their help, you can even screw the electrode into frozen soil at a shallow freezing depth. When manufacturing electrodes with a spiral, it is necessary to take into account the direction of rotation of the used deepener, since in some designs of electric deepeners with a gearbox the rotation is left-handed, and the screw electrode must correspond to this, otherwise the electrode will be slowed down while screwing in.

________________

* Numbering of drawings 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 helix and welded to the electrode: b - the lower end of the electrode is widened 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; d - tip with a curved and welded steel washer

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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 transmission lines (PTLs) are used, providing high-power electricity traffic over the required distances. Bringing the parameters of the energy transmitted through them to the standards characteristic of its consumers implies the use of transformer substations that provide the necessary voltage in the network. Thus, all electrical installations are powered, from a light bulb in a room to industrial equipment.

To prevent injuries to service personnel and, especially, 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 do you need to ground power lines and substations?

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

If you touch such a pole, a person can be injured and even die. Therefore, installing 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 Electrical Installation Rules (ELR) 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 mandatory.

The issue of lightning protection of structures stands apart. The supports can be made of wood, reinforced concrete or steel. For supports standing in an open field, sometimes having a very significant height, being struck by lightning is by no means a rare occurrence. If for steel or reinforced concrete, which have good electrical conductivity and are incapable of combustion, this will not cause serious damage, then for a wooden structure it is fraught with destruction or ignition. Considering the colossal voltage of a lightning discharge, it is possible to destroy the dielectrics that protect 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 a field, powering a farm, for example. Transformer installations are subject to all the negative influences 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 hits the support will flow to the ground, given its low resistance and huge capacity. This means that the structure will not be energized and will be safe for human life and health.

Basic Requirements

According to the requirements of the PUE, almost every support must have a grounding device. It is necessary to prevent atmospheric overvoltage (lightning), protect electrical equipment located on the mast, and also implement re-grounding. Its resistance should not exceed 30 Ohms. Moreover, lightning rods and similar devices must be connected to the ground electrode by a separate conductor. Among other things, guy wires installed for support stability, if they are present in its design, must be grounded. It is preferable to weld all interconnections, reduction wires and grounding wires, for example, and, if not possible, bolt them together. 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 galvanized steel wire of the appropriate diameter.

Reinforced concrete pillars

The grounding device for overhead lines depends on the material of the supports. In the case of a reinforced concrete structure, all reinforcement elements protruding from above and below must be connected to a 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 metal overhead line masts.

Wooden pillars

With wooden overhead line supports, the situation is somewhat different. Due to the dielectric properties of wood, each of the masts does not require 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 points where the overhead line transitions into 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 hours at which thunderstorms occur. 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. In addition, supports representing branching from overhead lines to objects with potentially large crowds of people, clubs, etc. or a cultural center, for example.

Installation of ground electrodes

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

Features of substations

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

In general, substation grounding consists of the following elements:

• inner circuit;
• outer contour;
• facility lightning protection device.

The internal grounding loop of the substation provides a simple and reliable connection to the ground of all devices located inside the substation. To do this, a steel strip is secured with dowels along the perimeter of all premises of the facility at a height of 40 cm from the floor. The contours of all premises, as well as their component parts, are connected by welding or threaded connections, if provided. All metal parts not intended for the passage of current (instrument housings, fences, hatches, etc.) are connected to this bus. Such strips are equipped with threaded connections with increased width washers and wing nuts. This allows you to obtain 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.

External contour

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

The device must be located around the perimeter of the building, not exceeding a distance of 1 m from its walls or foundation slab. The total circuit resistance cannot exceed 40 Ohms if the soil resistivity is less than 1 kOhm*m in accordance with the PUE.

If the substation has a metal roof, then it is grounded by connecting it to the external circuit with steel wire with a diameter of 8 mm. The connection is made from two sides of the object, diametrically opposite to each other. The requirements of the PUE require that this reduction bus on the external wall of the building be protected from corrosion and mechanical damage.

Calculation of the substation grounding device is performed to determine the resistance of the system current to propagate 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 extensive 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 of burial in a known type of soil.

Grounding devices of substations or overhead lines, as well as grounding of a power plant, play an extremely 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.