Grounding traverse 10 sq.m. Why do you need to re-ground the VLI? Scope of application

Outdoor lighting in cities and villages plays a very 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 overhead power poles prevents the spread of electrical potential and a decrease in 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. Increased requirements apply to the grounding of wooden supports. It can only take place in those populated areas where the height of buildings does not exceed 2 floors. Also, pipes in a populated area 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.

GROUNDING OF OVERHEAD POWER LINES

To increase the reliability of power lines, to protect electrical equipment from atmospheric and internal overvoltages, as well as to ensure safety service personnel Power line supports must be grounded.

The resistance value of grounding devices is standardized by the "Rules for Electrical Installations".

On overhead power lines with a voltage of 0.4 kV with reinforced concrete supports in networks with an insulated neutral, both the support reinforcement and the hooks and pins of the phase wires must be grounded. The resistance of the grounding device should not exceed 50 Ohms.

In networks with a grounded neutral, the hooks and pins of phase wires installed on reinforced concrete supports, as well as the fittings of these supports, must be connected to the neutral grounded wire. Grounding and neutral conductors in all cases must have a diameter of at least 6 mm.

On overhead power lines with a voltage of 6-10 kV, all metal and reinforced concrete supports must be grounded, as well as wooden supports, on which lightning protection devices, power or instrument transformers, disconnectors, fuses or other devices are installed.

The resistances of the grounding devices of the supports are accepted for populated areas not higher than those given in the table. 18, and in uninhabited areas in soils with a soil resistivity of up to 100 Ohm m - no more than 30 Ohm, and in soils with a resistivity above 100 Ohm m - no more than 0.3. When using ShF 10-G, ShF 20-V and ShS 10-G insulators on power lines for a voltage of 6-10 kV, the grounding resistance of poles in uninhabited areas is not standardized.

Table 18

Resistance of grounding devices of power transmission line supports

for voltage 6-10 kV

#G0Soil resistivity, Ohm m	Grounding device resistance, Ohm
Up to 100	Up to 10
100-500	" 15
500-1000	" 20
1000-5000	" 30
More than 5000	6·10

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 #M12293 0 1200003114 3645986701 3867774713 77 4092901925 584910322 1540216064 77 77 PUE#S . 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.

Grounding devices consist of grounding conductors and grounding slopes connecting the grounding conductors to the grounding elements. All elements of the stressed reinforcement of the racks that are connected to the ground electrode should be used as grounding slopes of reinforced concrete transmission line supports for a voltage of 6-10 kV. If the supports are installed on guys, then the guys of the reinforced concrete supports should also be used as grounding conductors in addition to the reinforcement. Grounding slopes specially laid along the support must have a cross-section of at least 35 mm or a diameter of at least 10 mm.

On overhead power lines with wooden supports it is recommended to use bolted connection grounding descents; on metal and reinforced concrete supports, the connection of grounding slopes can be made either welded or bolted.

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 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.

When installing supports on piles, a metal pile can be used as a grounding conductor, to which the grounding outlet of the reinforced concrete supports is connected by welding.

To reduce the area of land occupied by the ground electrode, deep ground electrodes are used in the form of round steel rods, immersed vertically into the ground for 10-20 m or more. On the contrary, in dense or rocky soils, where it is impossible to bury vertical grounding conductors, surface horizontal grounding conductors are used, which are several beams of strip or round steel, laid in the ground at a shallow depth and connected to a grounding descent.

All types of grounding significantly reduce the magnitude of atmospheric and internal overvoltages on power lines. However, these protective grounding in some cases it is not enough to protect the insulation of power lines and electrical equipment from overvoltages. Therefore, they install on the lines additional devices, which primarily include protective spark gaps, tubular and valve arresters.

The protective property of the spark gap is based on the creation of a “weak” point in the line. Isolation of the spark gap, i.e. the air distance between its electrodes is such that its electrical strength is sufficient to withstand the operating voltage of the power line and prevent the operating current from shorting to ground, and at the same time it is weaker than the line insulation. When lightning strikes power transmission line wires, the lightning discharge breaks through the “weak” spot (spark gap) and passes into the ground without breaking the line insulation. Protective spark gaps 1 (Fig. 22, a, b) consist of two metal electrodes 2 installed at a certain distance from each other. One electrode is connected to wire 6 of the power line and is isolated from the support by insulator 5, and the other is grounded (4). An additional protective gap 3 is connected to the second electrode. On 6-10 kV lines with pin insulators, the electrodes are shaped like horns, which ensures arc stretching during discharge. In addition, on this power line, protective gaps are installed directly on the grounding slope laid along the support (Fig. 23).

Rice. 22. Protective spark gap for power lines for voltages up to 10 kV:

a - electrical diagram; b - installation diagram

Rice. 23. Arrangement of a protective gap on the support

Tubular and valve arresters are installed, as a rule, at approaches to substations, power line crossings through communication lines and power lines, electrified railways, as well as to protect cable inserts on power lines. Arresters are devices that have spark gaps and devices for extinguishing the arc. They are installed in the same way as protective gaps - parallel to the insulation being protected.

Valve arresters type PB are designed to protect the insulation of electrical equipment from atmospheric overvoltages. They are produced for voltages of 3.6 and 10 kV and can be installed both outdoors - on power lines - and indoors. The main electrical characteristics of the arresters are given in Table. 19. The design, overall, installation and connection dimensions of the arresters are shown in Fig. 24.

Table 19

Characteristics of valve arresters

#G0 Indicators	RVO-0.5	RVO-3	RVO-6	RVO-10
Rated voltage, kV
Breakdown voltage at a frequency of 50 Hz in a dry state and in the rain, kV:
no less
no more				30,5
Leakage distance of external insulation (not less), cm
Weight, kg

Fig. 24 Valve arrester type RVO:

1 - bolt M8x20; 2 - tire; 3 - spark gap; 4 - two M10x25 bolts for fastening

arrester; 5 - resistor; 6 - clamp; 7 - M8x20 bolt for connecting the ground wire

The spark gap consists of a multiple spark gap 3 and a resistor 5, which are enclosed in a hermetically sealed porcelain cover 2. The porcelain cover is designed to protect the internal elements of the spark gap from the external environment and ensure stability of the characteristics. The resistor consists of vilitic disks made of silicon carbide and has a nonlinear current-voltage characteristic, i.e. its resistance decreases under the influence of high voltage, and vice versa.

A multiple spark gap consists of several single gaps, which is formed by two shaped brass electrodes separated by an insulating gasket.

When an overvoltage that is dangerous for the insulation of equipment occurs, a breakdown of the spark gap occurs, and the resistor finds itself under high voltage. The resistance of the resistor decreases sharply and the lightning current passes through it without creating a voltage increase that is dangerous for the insulation. The accompanying power frequency current following the breakdown of the spark gap is interrupted when the voltage first passes through zero.

The letter marking of the arresters indicates the type and design of the arrester, and the numbers indicate the rated voltage.

Tubular spark gaps (Fig. 25) are an insulating tube 1 with an internal spark gap, which is formed by two metal electrodes 2 and 3. The pipe is made of gas-generating material and one of its sides is tightly closed. When lightning strikes, a spark gap breaks through and an arc appears between the electrodes. Under the influence of high arc temperature, gases are rapidly released from the insulating tube and the pressure in it rises. Under the influence of this pressure, gases escape through the open end of the tube, thereby creating a longitudinal blast that stretches and cools the arc. When the accompanying current passes through the zero position, the stretched and cooled arc goes out and the current is interrupted. To protect the surface of the insulating tube from destruction by leakage currents, an external spark gap is arranged in the tubular spark gap.

Figure 25. Tubular arrester

Tubular arresters are produced in fibrobakelite type RTF or vinyl plastic type RTV. The characteristics of tubular arresters are given in table. 20.

Table 20

Characteristics of tubular arresters

#G0 Arrester type

Rated voltage, kV

External spark gap length, mm

TYPICAL TECHNOLOGICAL CARD (TTK)

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

I. SCOPE OF APPLICATION

1.1. A standard 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 the technological process and defining the composition of production operations using the most modern means 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. TTC is integral part Work production projects (hereinafter referred to as WPR) and are 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, measures for industrial safety and labor protection.

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 specifications(THAT);

- 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 recommended regulatory documents production process diagram installation work for grounding reinforced concrete supports of the overhead power supply line 10 kV, in order to ensure their high quality, and also:

- 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. Workers are being developed on the basis of the TTK technological maps(RTK) to perform certain types of work (SNiP 3.01.01-85* "Organization of construction production") to ground 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 lines	- *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 grinder PWS 750-125 from Bosch (P=1.9 kg; N=750 W); manual injection gas burner R2A-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 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 order of operation executive documentation during construction, reconstruction, major renovation capital construction projects and requirements for inspection reports of works, structures, sections of engineering and technical 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 "Construction organization. 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 project 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 manual machines, tools and personal protective equipment;

- provide construction site 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 to the work area necessary materials, devices, equipment;

- 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;

- current measurement short circuit electrical installations, checking the condition of blow-out 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 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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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. Grounding hooks and rotary grounding of the 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 automatic sectioning separator on 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

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Organizations:

15.06.1971	Approved		245
	Designed by

In the modern world, lighting surrounds us everywhere: both at home and on the street. Moreover, the role of outdoor lighting is very important in cities and villages, because it allows you to avoid many problems in the evening and at night.
When creating an outdoor type of lighting, one of the important stages of installation is grounding the supports.

During grounding for outdoor lighting supports, it is necessary to understand and know the basic rules that are regulated by the relevant documentation (for example, PUE). This procedure is especially important for overhead lines (OHL) and a network of outdoor lighting supports. We will talk about everything related to this procedure in this article.

What is it for?

Outdoor lighting system supports

Grounding for a network of outdoor lighting poles or overhead lines (0.4, 6-10, 20 and 35 kV) is of great importance, since it prevents the risk of electrical injury when coming into contact with structural elements in a situation where cable insulation is damaged. If there is grounding on a metal support of an outdoor lighting network or overhead line, the voltage “spreads” along the ground, thereby becoming safe for people. This indicator depends on the resistance of the soil in which the overhead line support is installed (0.4, 6-10, 20 and 35 kV). As a result, even if a violation of the overhead line insulation occurs somewhere, the structures will remain safe.

Under normal operating conditions, pin insulators mounted on supports will provide reliable insulation of all wires from structural elements. But there are situations when the network voltage
significantly exceeds the voltage for which the overhead line was designed (0.4, 6-10, 20 and 35 kV). In such an overvoltage situation, a breakdown of the overhead line insulation is possible and, as a result, the network fails.
In order to limit the value of overvoltage and improve safety, it is necessary to reduce the resistance for "current spreading". For this purpose, protective grounding is installed on overhead lines (0.4, 6-10, 20 and 35 kV) and supports for external lighting.

Features of the procedure

Grounding of metal supports

The ground loop is formed based on what the support was made of. Today, three design options are used:

reinforced concrete. Here, if there is a network with a grounded neutral, together with the reinforcement of the structures, protection is provided by connecting a special conductor to the grounded wire (neutral). The latter should have a diameter of 6 mm (not less);
wooden. On wooden supports, pins and hooks are not grounded;

Pay attention! Grounding on wooden poles is installed only when power lines or outdoor lighting systems pass through populated areas where there are one- and two-story buildings. A populated area in such a situation should also not have excessively elevated pipes (screened), trees, etc. Here there is a need to protect the network from atmospheric surges using grounding devices. Their resistance is up to 30 Ohms (no more).

metal supports. Here the protection is done by analogy with reinforced concrete structures. Such supports are most common. They are gradually replacing wooden and even reinforced concrete supports from use.

When grounding overhead lines (0.4, 6-10, 20 and 35 kV), it is necessary to take into account the distance between adjacent supports. Usually the distance between them is 100 or 200 m. This parameter is determined by the average annual number of thunderstorms characteristic of a given area.
It is imperative to ground the supports (repeatedly or not) that have a branch to structures where a large number of people are located.
To protect against overvoltage, two types of grounding conductors are used:

vertical pins that are buried vertically into the ground;
horizontal plates. Such ground electrodes are usually used for rocky soils.

The type of grounding conductors is determined by the type of soil at the site of installation of overhead line supports (0.4, 6-10, 20 and 35 kV) or external lighting.

How the procedure itself works

Installation of ground electrodes

Installation of grounding (repeated or not) for overhead lines (0.4, 6-10, 20 and 35 kV), power transmission networks or outdoor lighting poles is carried out as follows:

We dig a trench (about 0.5 m). A trench depth of up to 1 m is needed for arable land. The depth must be measured from the beginning of the supports;
the length of the trench, as well as the number of grounding conductors must be indicated in the design for the construction of overhead lines (0.4, 6-10, 20 and 35 kV);
then we immerse the grounding conductors, forming a circuit;
then scalding occurs (either with a rod or a strip);
After this, the welding joints are protected from possible corrosion.

After the grounding loop, a grounding drain is installed. It is made of steel rod or strip and has the same dimensions as the connection installed between the grounding conductors. The protection circuit is connected to the drain from below. The descent from above is connected to metal non-conductive parts of the support structure.
This procedure is clearly visible in the figure.

Grounding on a support (wooden):

a - general appearance, b - hook grounding option

A connecting strip (2) and a descent (3) are connected to the wooden support after the circuit (grounding conductor 1 and 2). Here the descent is often mounted (step - 300 mm), fastened with staples. In this case, the descent, or rather its upper part (4), will protrude above the support, acting as a lightning rod. Figure (b) shows grounding for a metal pole in a power transmission network or outdoor lighting. The surge protection circuit here will also be connected to the drain (1). But in this situation, the descent will be connected by welding the jumper (2) or bolt clamps, which direct the zero ground potential to the neutral wire (3) and the hook (4).

PUE requirements

The PUE is regulatory documentation that should be relied upon when implementing protective grounding measures (repeated or not) of power transmission network supports or outdoor lighting. The ground loop should always be installed according to these rules to avoid problems in the future.
The PUE contains the following recommendations:

if there is an electrical installation with a solidly grounded neutral, first of all the neutral wires of the beginning of the overhead line should be grounded;

Grounding on each support

Pay attention! In this situation, the ground loop does not need to be installed at the first support. This is due to the fact that here the neutral wire will be tightly connected to the neutral point of the power source.

Protective grounding:
1 – places for welding; 2 – the ground electrode itself; 3 – conductor to the ground electrode.

in the presence of electrical installations with a solidly grounded neutral, repeated grounding as overvoltage protection should not be installed very often (step - kilometer of line);
any subsequent re-grounding must have a resistance of up to 10 ohms (maximum). If there is an installation with a power of more than 100 kVA. If the installation power is lower, then the resistance should be up to 30 Ohms (maximum);
For overhead line supports, grounding devices must be installed if repeated overvoltage protection is necessary. It is allowed to use structures for protection against overvoltages of natural origin (lightning). In this situation, the resistance for the grounding device should be taken no higher than 30 Ohms;
any metal structures must be connected to special PEN conductors;
if there are reinforced concrete supports, special PEN conductors must be connected to the reinforcement of the struts and support posts;
When installing self-supporting insulated wires that have insulated supporting conductors, supports (reinforced concrete and metal wooden, for overhead lines) are not subject to surge protection. Here re-grounding is needed for pins and hooks. This is done in order to form protection against overvoltages of atmospheric origin.

Peculiarities

When forming grounding for overhead lines up to 1 kV, the following nuances should be adhered to:

if there is a network with a grounded neutral, a jumper is made from a non-insulated conductor for the reinforcement of supports (reinforced concrete/metal). It is connected to the neutral wire using bolt clamps (branch clamps);
the contact connections of the jumper must be thoroughly cleaned and coated with Vaseline before installing it;
If there is a network with an isolated neutral for the same supports, protection is installed by connecting special grounding devices. In this case, the resistance of these structures should not exceed the 50 Ohm level;
Grounding of structures for creating an external lighting system in the presence of cable power is carried out through the metal sheath of the cable. This occurs if there is a grounded neutral.

In other situations, everything is determined by the types of systems, supports and other components.

Conclusion

When creating grounding on various types of supports included in an external lighting system or overhead line, it is imperative to follow the established rules and recommendations given in the PUE. This is the only way to achieve high-quality and correct grounding, which will protect the supports from damage to the cable insulation and prevent risk situations when people can be electrocuted when touching the supports.

Choosing a box for LED strips, correct installation