Regulations for the operation of an integrated system for the protection of facilities of the Organizations of the "transneft" system from the impact of hazardous factors of lightning, static electricity and sparking. Inspection, verification and testing of grounding devices

Visible parts of grounding devices should be carried out at least once every 6 months. Inspection with selective soil opening should be carried out at least once every 12 years.

The frequency of measurement of the resistance of the grounding device is carried out in accordance with Appendix 3, clause 26. "Grounding devices", namely:
1) Grounding device for overhead power transmission lines with voltages up to 1000 V - at least once every 6 years, and for overhead lines above 1000 V - at least once every 12 years.
2) Earthing device of electrical installations in accordance with the scheduled preventive maintenance (PPR) schedule, but at least once every 12 years.

PTEEP
2.7.8
To determine the technical condition of the grounding device, visual inspections of the visible part, inspections of the grounding device with selective soil opening, measurement of the parameters of the grounding device in accordance with the standards for testing electrical equipment (Appendix 3) should be carried out.

2.7.9
Visual inspections of the visible part of the grounding device should be carried out according to the schedule, but at least once every 6 months, by the person responsible for the consumer's electrical equipment or by an employee authorized by him.
During the inspection, the condition of the contact connections between the protective conductor and the equipment, the presence of an anti-corrosion coating, and the absence of breaks are assessed.
The results of inspections should be entered in the passport of the grounding device.

2.7.10
Inspections with selective soil opening in places most susceptible to corrosion, as well as near places of grounding of neutrals of power transformers, connections of surge arresters and surge arresters should be carried out in accordance with the schedule of preventive maintenance (hereinafter - PPR), but at least once every 12 years.
The size of the section of the grounding device subject to selective soil opening (except for overhead lines in a populated area - see clause 2.7.11) is determined by the decision of the technical manager of the Consumer.

2.7.11
Selective soil excavation is carried out on all grounding devices of the consumer's electrical installations; for overhead lines in populated areas, the opening is performed selectively at 2% of the supports with grounding devices.

2.7.12
In areas with high soil aggressiveness, by decision of the technical manager of the Consumer, a more frequent inspection frequency with selective soil opening can be established.
When opening the pound, an instrumental assessment of the condition of the grounding conductors and an assessment of the degree of corrosion of contact connections should be made. The earthing element must be replaced if more than 50% of its cross-section is destroyed.
The results of the inspections must be documented in acts.

2.7.13
To determine the technical condition of the grounding device in accordance with the standards for testing electrical equipment (Appendix 3), the following should be performed:
measurement of the resistance of the grounding device;
measuring the touch voltage (in electrical installations, the grounding device of which is made according to the standards for touch voltage), checking the presence of a circuit between the grounding device and the grounded elements, as well as the connections of natural grounding devices with the grounding device;
measurement of short-circuit currents of electrical installations, checking the status of breakdown
fuses;
measurement of soil resistivity in the area of the grounding device.
For overhead lines, measurements are made annually at supports with disconnectors, protective gaps, arresters, re-grounding of the neutral wire, and also selectively at 2% of reinforced concrete and metal supports in a populated area.
Measurements should be carried out during the period of the greatest drying out of the soil (for permafrost regions - during the period of the greatest freezing of the soil).
The measurement results are recorded in protocols.
At the main step-down substations and transformer substations, where it is impossible to disconnect the grounding conductors from the equipment according to the conditions for ensuring the categorization of power supply, the technical condition of the grounding device should be assessed based on the results of measurements and in accordance with clauses 2.7.9-11.

2.7.14
Measurements of the parameters of grounding devices - resistance of the grounding device, touch voltage, checking the presence of a circuit between grounding electrodes and grounded elements - is also performed after reconstruction and repair of grounding devices, upon detection of destruction or overlapping of insulators of overhead lines by an electric arc.
If necessary, measures should be taken to bring the parameters of the grounding devices up to standard.

2.7.15
For each in operation, grounding device must have a passport containing:
executive scheme of the device with links to capital structures;
the connection with overground and underground utilities and with other grounding devices is indicated;
commissioning date;
basic parameters of ground electrodes (material, profile, linear dimensions);
the value of the resistance to the spreading of the current of the grounding device;
soil resistivity;
touch voltage data (if necessary);
data on the degree of corrosion of artificial grounding conductors;
data on resistance of metal connection of equipment with a grounding device;
list of inspections and detected defects;
information on the elimination of remarks and defects.
The passport must be accompanied by the results of visual inspections, inspections with soil opening, protocols for measuring the parameters of the grounding device, data on the nature of repairs and changes made to the design of the device.

26. Grounding devices
К, Т, М - are produced within the terms set by the PPP system.
26.4. Measurement of resistances of grounding devices:
1) supports of overhead power lines:

Test standards:
The values of the resistances of the earthing switches of the supports are given in table 35 (Appendix 3.1)

Directions:
They are made after repairs, but at least once every 6 years for overhead lines with voltages up to 1000V and 12 years for overhead lines above 1000V on supports with arresters and other electrical equipment and selectively for 2% of metal and reinforced concrete supports in areas in populated areas. Measurements are also carried out after reconstruction and repair of grounding devices, as well as upon detection of destruction or traces of overlapping insulators by an electric arc.

2) electrical installations, except for overhead power lines:

Test standards:
The values of the resistances of the grounding devices of electrical installations are given in table 36 (Appendix 3.1)

Read also:

Victor Is it possible to connect the ground loop with an iron fence or a frame of terraces made of iron pipes to achieve the required resistance of the grounding device? Answer: You have the right to attach metal poles fence and metal frame ...
Victor Hello, tell me, please, I am moving the apartment out of the housing stock in the municipal building and I want to change the point of connection to the electrical networks (disconnect from the general house electricity meter). At the moment I ...
Arthur Tell me, electrical installation of the ground loop, can it be carried out at an unfinished facility? Thank you. The electrical installation of the ground loop can be performed at any stage of construction. ...
Victor Stepanovich Dear specialists, I am going to make a ground loop in the country. How to determine the place for driving stakes? Is it possible to use instead of stakes metal fence? What is it fraught with? Your electrical contractor takes on ...
Alexander When are the resistance measurements of grounding devices carried out? Answer: Measurements of the resistance of the grounding device (measurement of the ground loop) must be performed during the period of the greatest drying out of the soil. PTEEP 2.7.13 To determine the technical condition of the grounding device in accordance with the test standards for electrical equipment ...

14 Comment (s) on “What is the frequency of checking the ground loop?”

Please tell me on what basis do you think that: "The frequency of measurement of the resistance of the grounding device is carried out in accordance with Appendix 3, p. 26." Grounding devices ", namely:

2) Earthing device for electrical installations in accordance with the scheduled preventive maintenance (PPR) schedule, but at least once every 12 years. "
in PTEEP app. 3 p. 26 it is missing

Hello Konstantin!
Read carefully PTEEP, clauses 2.7.13 and 2.7.14.

Tell me who would not please !!! What means is used to check the quality of ground electrodes? At least what sources can you use?

Hello Roman!
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Hello. At uchatsk, 10 km away, an armored trunk communication cable has been laid. Every 2 km there is a tap to the objects. Each tap has its own circuit which is connected to the cable sheath. In this case, what routine maintenance should be carried out and with what frequency? Thank you

Hello Andrei!
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Good afternoon. Can you enlighten me on a very difficult question in my opinion: when on construction industrial enterprises and in residential construction, electricians connect 2 wires under one grounding bolt, coming, for example, from two adjacent boards, are they right? I believe that they are wrong, because in the PUE there is a requirement (1.7.119 - PUE 7th) to the main grounding bus - “The bus design should provide for the possibility of individual disconnection of the conductors connected to it. Disconnection should only be possible with a tool. " Does this mean that in general, absolutely everywhere and not only on the GZSH, ONLY one grounding wire should be clamped under one bolt? This opinion or understanding breaks down the work of one scientist - R.N. KARYAKIN, Doctor of Technical Sciences, Professor of NORMS FOR EARTHING NETWORKS, MOSCOW, Energoservice, 2002. There he writes this (by the way, he interprets GOST R 50571 (MEK364) including): “10.5.4. It is prohibited to connect more than two-cable lugs to one nulling bolt (screw). On the grounding (zero) bus, bolted connections of the required number of grounding, zero protective inul working conductors must be provided.
10.5.5. It is not required to deliberately nullify the enclosures of electrical equipment and devices installed on the null metal structures, switchgears, boards, cabinets, shields, machine beds, machines and mechanisms, provided that reliable electrical contact with neutralized bases is ensured. " That is, the author states that no more than two tips can be placed under the bolt. But he described this for shields, obviously for a bolt inside the shields, and not for wires with lugs that fit on the bolts of the ground loop, which usually runs nearby. GOST 10434-82 also states that it is allowed to plant 2 grounding wires under one bolt (Excerpt from GOST: (Changed edition, Amendments No. 1, 2).
2.1.12. It is recommended to connect no more than two conductors to each bolt (screw) of a flat terminal or to a pin terminal, unless otherwise specified in the standards or technical conditions for specific types of electrical devices.), But this GOST seems to be general technical and at the beginning of its text the following is written: in part of the permissible value of electrical resistance and resistance of contact connections at through currents also apply to contact connections in the chains of grounding and protective conductors made of steel.
The standard does not apply to electrical contact connections of electrical devices special purpose. " There is a confusion of opinions and all as one documents bypass the exact indication - one or two still wires (tips) need to be planted under one bolt. Why is it exactly about the GZS in PUE 7, but nothing is written exactly about the rest of the grounding and, in particular, about my question that I have voiced? Please help me figure out how to understand all this and come to some kind of correct understanding. Thanks!

Hello Eugene!
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In the project of a monolithic residential building, lightning protection down conductors were adopted inside the monolithic pylons. I asked to make outlets of the down conductors from the pylons above the ground in order to connect the down conductor to the outer ground loop. But the customers considered that it would be "ugly" and demanded to make outlets underground and connect the down conductors directly underground to the circuit. Can you do this? Will this not lead to problems when checking the lightning protection performance? I would like to leave the control connection above the ground for verification, but I cannot find the mandatory requirement for the device of the control connection

Hello Andrei!
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Good day.
I have this question. What is the frequency of checking the resistance of the ground loop of the enterprise (plant)? Who should measure resistance?

Hello Vladimir!
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Grounding devices are conductive structures that provide a connection to earth through a metal conductor. Grounding works as follows: an electric current passes through a conductor with a low resistance, creating potentials. With distance from the ground electrode, the potential tends to zero. The resistance that the soil has to current is called « spreading resistance ". In practice, the spreading resistance is referred not to the ground, but to the ground electrode, and the abbreviated conventional term "ground electrode resistance" is used. In winter, when the ground freezes, and in summer, when the soil is overdried, the inductive resistance is maximum at a constant active resistance (resistance of the ground electrode). If a grounding device loses contact with ground, it will be energized and dangerous. In the same way, it is dangerous if the value of the resistance of the ground electrode does not correspond to the standard values, if there is corrosion and breaks in the ground electrode, a change in the potential difference curve is observed. In order for the grounding device to work efficiently, it is required to regularly inspect, check and test and measure it.

Grounding devices: condition inspection

contacts with equipment;
contact connection to the ground;
fastening conductors;
assessment of the impact on the conductors of the external environment;
the degree of corrosion;
presence or absence of heating.

Together with an external examination of grounding electrodes, as a rule, a visual check of all electrical equipment is carried out.

When examining the condition, it is important to pay attention to the conditions under which the chargers work and for how long. So, for example, the constant presence in the open air, in conditions of high humidity and precipitation (including snow, which creates a strong pressure upon adhesion, stretching the cables, which in turn changes the potentials), leads to the fact that, with external stability, the grounding the device is practically inoperative. Sometimes this fact masks the decorative and protective coating, and also hides - if access is inconvenient for inspection - the details of equipment, buildings and structures. Damaged grounding devices are inoperative and must be repaired (restored) or replaced.

Grounding devices: check

Checking grounding devices occurs after inspection - first, those nodes that are in doubt are checked. So, ties and fasteners are checked for strength, loosened bolt connections are tightened, parts damaged by the external environment are painted. This is the so-called cosmetic renovation. It must be carried out regularly, and it is quite possible to carry it out by the efforts of the employees of the electrical equipment of the enterprise itself.

There is also a major renovation. During the overhaul, new electrodes of grounding devices are manufactured, as well as grounding conductors, rusted and worn out fasteners are replaced, and a number of other activities are carried out regarding the maintenance of grounding devices. This includes drawing up and adjusting the schedule for examining and checking the memory, planning and training according to the plan of specialists responsible for electrical equipment, checking the knowledge of safety measures and techniques among personnel.

Due to the fact that the resistance of the conductors themselves, and most importantly of the soil, changes depending on the season, temperature and humidity, grounding devices are checked in several stages. The first one is at normal humidity, average annual temperature. The second is in extreme humidity. The third - at the maximum soil resistance (in winter or in the midst of a summer drought). As a rule, it turns out that when the ground freezes or dries out, the resistance of the soil turns out to be high, which leads, in fact, to the inoperability of the grounding system in normal mode. If it is required to reduce the grounding resistance to normal performance, you can use additional electrodes or install a new ground loop. To assess the state of the charger, it is also required to open the ground at the grounding points and measure the parameters of the charger itself. Normative document defining the sequence of operations and standardized values of the memory in operation: "Guidelines for monitoring the state of grounding devices of electrical installations" - RD 153-34.0-20.525-00

Installation of a new grounding device

The inspection, verification and testing of grounding devices also includes a study of documentation, including hidden works: installation certificates, measurement protocols, executive drawings and other technical documentation... They must indicate the location, configuration and potentials of all grounding devices and lightning protection elements. If it is necessary to alter or change the grounding device, or install a new one, it is necessary to recalculate working together memory network to avoid conflicts between devices. A new grounding device is required to be installed not only to reduce the regular high resistance: according to experts' calculations, steel structures lose up to 2.5 mm thickness in the ground every 10 years, therefore, if the ground electrode system is made of strip steel 5 mm thick, then it is obvious that corrosion will be more than 50% and the electrode will need to be replaced. However, it is not required to wait all 10 years - if half of the useful mass is lost, the electrode is already considered inoperative. In general, the calculation of the timing of replacement of grounding devices is quite easy to do - by the thickness of the element and the corrosion coefficient. So, for steel, the replacement period will be the number of years, which is identical to the thickness of the strip. With a thickness of 8 mm, replacement should occur after 8 years, 4 mm - 4 years, 5 mm - 5 years. These are the recommended periods, although ground electrodes can operate longer, losing a certain percentage of efficiency every year, which increases the risk of lack of grounding efficiency in an emergency. In the example shown, we used strip steel, but the aging of angle steel, round steel or pipes can be calculated in the same way.

To find out exactly whether it is necessary to change the ground electrodes, it is enough to measure the amount of corrosion of the elements of the grounding device and use the recommendations of the Normative Document. If it is 50% or more, it is recommended to replace it immediately. According to the recommendations of specialists, “inspections with selective soil opening in places most susceptible to corrosion, as well as near places of grounding of neutrals of power transformers, connections of surge arresters and surge arresters should be carried out in accordance with the schedule of preventive maintenance (hereinafter - PPR), but not less often once every 12 years. The size of the section of the grounding device subject to selective soil opening (except for overhead lines in populated areas) is determined by the decision of the technical manager of the consumer based on the requirements of ND.

Grounding devices: testing

An important point in the completion of work on the replacement and monitoring of grounding devices is its testing. It can be carried out only after the completion of major or current repairs. Note that the algorithms in both cases are different: after the current repair, the continuity of the circuit is measured using instruments or measuring instruments to measure resistance or grounding parameters such as MS-08, F4103 or their analogs. After a major overhaul, in addition to the above, the following is measured:

the success of melting the fuse-link of the fuse (by creating an artificial short circuit);
measurement of the resistance of the "phase-zero" loop with a dead neutral ground;
check of breakdown fuses;
measurement of spark gaps.

When testing grounding devices, a smooth increase in voltage is required, for which rheostats installed in the transformer circuit are used. In this case, the voltage must be applied after checking the condition and resistance of the insulation of the line, and if it turns out to be in an improper condition, then these defects must be eliminated before testing the grounding devices.

It is practically impossible to carry out the entire range of these measures on your own without involving specialists from the electrical measuring laboratory, since work is required both with the documentation and directly with the equipment: taking into account the many conditions and restrictions on the operation of the equipment, carrying out multiple measurements. Therefore, it is necessary to involve qualified electric laboratory specialists with experience in these works and permits for their implementation to assess the state of grounding devices and lightning protection parameters.

Protocol (Act) grounding, can only be issued by a company registered with Rostekhnadzor and having a Certificate of registration of an electrical laboratory in accordance with the PUE and PTEEP.

PUE-7
1.8.5

Act and / or protocol.

PTEEP
3.6.13.

The results of tests, measurements and trials must be issued protocol and / or grounding act, which is stored along with the certificates for electrical equipment.

Electrical laboratory registration certificate

The electrical laboratory is a complex special equipment and professional specialists who will perform a wide range of power supply works.

The electrical laboratory of the Pushkin Energy and Gas Company is measuring resistance grounding based on the current
Electrical laboratory registration certificate.
Our company works with legal entities and individuals.

We conclude contracts for electrical laboratory services, which are documents that clearly define the cost and timing of work.

You cannot independently measure the resistance of grounding devices / circuit grounding, since for these tests it is necessary to make protocol (Act) measuring the resistance of the grounding device / protective circuit grounding.

Act (protocol) on the contour grounding gas boiler.

Act(protocol) on the contour grounding gas boiler. This document should be understood protocol(Act) checking the resistance of grounding conductors and grounding devices. Such a document is drawn up by specialists of the electrical laboratory, which has
state accreditation - registration of the electrical laboratory in Rostekhnadzor. V protocol (Act) the results are entered
measuring the resistance of the grounding device.

How to measure resistance grounding.

Resistance test grounding
any electrical circuit is based on the action of Ohm's law for the section of the circuit through which the current is passed and its magnitude is measured. A stabilized voltage is applied to the input of the tested circuit.
Usually chemical current sources are used for this:
- galvanic batteries;
- batteries.

Less commonly, rectified voltage from an alternating current network is used.

If the scheme grounding whole and there are no breaks in it, then the current will overcome the total resistance of the circuit, and its value will be expressed by the ratio I = U / R.

The permissible value of the resistance of the circuit grounding a value not exceeding 10 ohms is considered. Also, the experts of the electrical laboratory check whether the gas boiler is installed and connected correctly from the point of view of the PUE. For example, for many models of gas boilers, it is not critical correct connection zero and phase to the mains.

Why do you need to register an electrical laboratory with Rostekhnadzor?

When putting new electrical equipment and electrical installations into operation, during operation or after various emergencies, it is necessary to carry out a number of electrical measurements and circuit tests grounding, with the issuance of an act - protocol resistance measurements grounding and provide Act or a technical report on these tests and measurements.

Make out protocol resistance measurements grounding and / or Act can only be an electrical laboratory that has been registered with the Rostechnadzor authorities, with an appropriate authorized list of types of tests and measurements.

Registration with Rostekhnadzor, in accordance with the PUE and PTEEP, is required for those electrical laboratories that draw up the appropriate Act and / or protocol on the results of tests and measurements grounding.

Requirements for personnel who have permission to measure resistance grounding.

1. To measure the resistance of the protective circuit grounding and testing of electrical equipment is allowed by personnel,
passed special training and knowledge testing of the Occupational Safety Rules (safety rules) during operation
electrical installations by a commission, which includes equipment testing specialists who have group V - in electrical installations with voltages above 1000 V and group IV - in electrical installations with voltages up to 1000 V.

2. To measure the resistance of the protective circuit grounding and testing of electrical equipment, employees are allowed to be at least 18 years old who have passed a preliminary medical examination and do not have contraindications to perform this work.

PUE-7 1.8.5

All measurements, tests and testing in accordance with the current regulatory and technical documents, the instructions of the manufacturers and these standards, carried out by the personnel of the installation and commissioning organizations immediately before putting the electrical equipment into operation, must be executed accordingly. act and / or protocol resistance measurements grounding.

PTEEP 3.6.13
The test and measurement result must be documented protocol or Act, which are stored along with the certificates for electrical equipment.

Grounding act/ protocol resistance measurements grounding spreading current ( protocol checks grounding).

Act / protocol grounding,

resistance measurements grounding current spreading is the main document confirming the quality of the grounding device and the compliance of the system grounding, regulatory documents.

Protocol(grounding act) is issued by a certified electrical laboratory licensed by Rostekhnadzor.

Pushkinskaya EnergoGasovaya Company carries out work on the manufacture of a protective circuit grounding equipment, with the subsequent issuance of a certified act for the protective circuit grounding / protocol (Act) resistance measurements grounding.

Protective circuit device grounding.

All contacts are connected to the bus grounding, which is inside the shield.

Live parts are connected to the main ground bus to ensure the protection of all groups of electrical devices. Although the bus is the most important part of the EMS, there are many other parts to its design.

It is important to note that the tire is zero or grounding made of high strength metal alloy or metal.

All grounding elements with the system grounding are interconnected by means of a bus.

Grounding device / protective circuit grounding are used in order to protect a person's life if he touched the current-carrying conductors of electrical equipment or other objects that are energized. The electrical safety of buildings and portable equipment is ensured by the following operational functions of the grounding element:

Overcurrent is an emergency fire-hazardous mode in which a current flows through an element of the electrical network that exceeds the rated value for which this element is designed (wire, cable, electrical protection device and systems grounding).

Act grounding /protocol resistance measurements grounding - this is a document confirming the security of the network and allowing the use of electrical system object by people.

Before putting the facility into operation on a turnkey basis and after carrying out the entire range of necessary electrical work, the new electrical system needs to be tested for operability, reliability and safety. During such studies, specialists check all elements of the system. grounding

Resistance test grounding is carried out in order to assess the condition of grounding devices and insulation. Grounding devices must be in good working order, because only in this case the current from the damaged equipment will go into the ground through the protective electrodes. grounding.

Protocol(grounding act grounding.

In particular, these include the measurement of the value of soil resistance, as well as the results of visual inspection and technical analysis of the structure of this system. grounding.

The value of soil resistivity is an initial and fundamental parameter when carrying out resistance calculations. grounding... The higher this indicator is, the large quantity earthing switches will need to be installed in order to achieve the required resistance value grounding... When calculating a grounding device, you need to know the exact value of the soil resistivity at a specific place where the contour will be created. grounding.

Soil resistivity depends on many factors:
- temperature;
- humidity;
- composition, structure and compaction of the soil;
- the time of the year;
- the presence of salts, alkaline and acidic residues.

Accurate measurement of soil resistivity allows significant savings on the organization of the structure grounding... On the one hand, there is no need to install extra ground electrodes, on the other hand, there is no need to carry out additional measures after the completion of construction and commissioning of the facility, aimed at expanding (increasing) grounding devices - an additional protective circuit. grounding... To obtain the most reliable result, measurements should be carried out throughout the year, separately for each season.

Provided by protocol(grounding act) measuring the resistance of the protective circuit grounding is one of the steps towards concluding an Agreement for the supply of electricity to your home, as well as an Agreement for the supply of gas, if the facility uses volatile equipment.

How is protocol (grounding act) measuring loop resistance grounding?

At the very beginning, laboratory staff conduct a visual inspection of the contour grounding To do this, they must scan every inch of it for breaks, thinning and other defects that could disrupt the normal characteristics of the conductor.

Protocol (grounding act) measuring loop resistance grounding may also require a more detailed study, which includes tapping the main elements and connections with a hammer - when a copper-plated tool is struck, the ruptures emit a dull rattling sound, which is a signal of danger and indicates the need to repair the structure grounding.

In addition, it is necessary to conduct a technical analysis of the formed system. grounding/ contour designs grounding- for this, the main electrical circuits presented in the project.

What measurements include protocol (grounding act) loop resistance grounding?

Protocol (grounding act) measuring loop resistance
grounding is issued on the basis of comparison of the actual value and the standard value. Resistance tester grounding at the same time, it must be very carefully calibrated - for this it is better to invite specialists, and not to carry out such work on your own. A qualified professional can give you a guarantee of the obtained loop resistance measurement data. grounding.

What parameters are determined during the loop circuit check grounding.

1. Resistance to the spreading of the circuit current grounding and grounding devices.

This chain parameter grounding measured:
- at power plants and substations - after installation of the grounding device, overhaul and re-equipment. At substations of overhead lines of distribution networks with a voltage of not more than 35 kV, circuit check grounding held at least once every 12 years;
- on the grounding devices of tanks (as well as devices for protecting the object from static electricity) - during a major overhaul. Resistance Test Frequency grounding- every three years;
- on grounding devices for lightning protection (buildings, structures, tanks and tank farms) - every year before the onset of the thunderstorm season;
- on overhead lines - after installation, repairs and operation, at least one check per year.
2. Connections of ground electrodes with circuit elements grounding(metal connection).

Such a check is performed by tapping the joints with a hammer and visually inspecting the chain to identify breaks and other defects in the circuit circuit. grounding... At this stage of the design check grounding the resistance of the contact resistances is measured.

On a good contact connection of the circuit grounding resistance does not exceed 0.05 ohm.

Frequency of checking metal bonds in such areas of the chain grounding checked at least once every three years. Transient coupling resistance of elements grounding with a grounding device should not exceed 0.03 Ohm.

5. Soil resistivity - checked before starting the development of project documentation and after the installation of the grounding device and its connection to the protective circuit grounding.

Soil resistivity standards are not established. If the resistivity of the protective circuit grounding is more than 100 Ohm * m, an increase in the resistance rate of ground electrodes by 0.01 times is allowed.

The main task of any system grounding/ protective circuit grounding:

Is the protection of people from possible electric shock and electrical equipment connected to the network, from short circuits and failure.

System grounding(protective circuit grounding) is necessary to connect to the ground certain parts of the electrical system that are not energized. An electric current may appear on such elements, in the event of any wiring faults, it is such situations that are most dangerous to the life and health of people.

System task grounding/ protective circuit grounding is to promptly withdraw electric charge from the wiring elements into the ground and reduce the likelihood of a person being hit by electricity. This task is possible only if a route is organized for the movement of electricity along the contour. grounding with the least resistance, which will lead the charge into the ground. That is why the resistance level of the circuit grounding should be as low as possible.

To maintain the system grounding/ protective circuit grounding in a functional state and excluding the likelihood of the occurrence of the likelihood of hazardous situations for all
inhabitants of your house, system check grounding should be carried out not only in the process of carrying out commissioning works and research, before the commissioning of a power supply project for a residential building or other structure, but also at regular intervals during the use of the facility, and in this case the system grounding people.

Professional verification of resistance measurement parameters grounding at various sites.

At the same time, there are some rules for testing the protective circuit grounding characteristic for any objects. Any check begins with a visual inspection by specialists of the elements of the grounding circuit of the system. grounding/ protective circuit grounding located above the surface of the earth and not hidden by the structural elements of the building. After that, the masters tap hand tools joints of system elements grounding/ protective circuit grounding, and also look for possible defects or mechanical damage on parts of the structure of the grounding.

Actgrounding/ protocol circuit resistance measurements grounding gas boiler.

First of all, consider a document like protocol (grounding act) measuring loop resistance grounding gas boiler. This name is adopted for use in various bodies and organizations responsible for checking the compliance of all construction works uniform requirements, although it is not technical.

The full name of such a document is “ Protocol (grounding act) checking the resistances of ground electrodes and grounding devices ", but it is usually not used by gas services. In gas services, as a rule, this document is called - grounding act.

The question immediately arises: why is it necessary to equip the protective circuit grounding Houses? At first glance, the answer to this question is obvious.

Correctly installed safety circuit grounding, will reliably protect you in the house from any electric shock, in the event of: failure of various electrical appliances, short circuits and natural disasters such as thunderstorms or floods.

Grounding act/protocol resistance measurements grounding

Another thing is that, in addition to the established general contour of the protective grounding at home, the gas service will definitely require the installation of an additional circuit grounding for gas equipment and relevant documentation that would confirm the existence of such grounding - this is grounding act/ protocol resistance measurements grounding.

Here you need to carefully read the instructions and regulations that relate specifically to the gas industry in order to find answers to all kinds of circuit structures that arise during the installation process. grounding questions.

According to this instruction, for gas connection, the resistance grounding/ protective circuit grounding should be no more than 10 ohms. This must be confirmed by a special act. grounding -grounding act / protocol resistance measurements grounding electrical laboratories.

To connect a gas boiler, gas services require the provision of akt(protocol) on the contour z grounding gas boiler ".

This document should be understood as “ Protocol (Act grounding and grounding devices ". Such a document is drawn up by specialists of the electrotechnical laboratory, which has state accreditation.

V protocol(Act) checking the resistance of the circuit grounding the results of measuring the resistance of the grounding device are recorded. Allowable circuit resistance grounding a value not exceeding 10 ohms is considered.

Also, the experts of the electrical laboratory check whether the gas boiler is installed and connected correctly from the point of view of the PUE. For example, for many models of gas boilers, the correct connection of the zero and phase of the supply network is critical.

Household gas is a serious hazard. At a certain concentration, the gas / air mixture becomes explosive. The slightest spark can cause an explosion or fire. Therefore, very stringent requirements are imposed on gas equipment.

Gas services strictly monitor compliance with all standards when connecting gas equipment and connecting this equipment to the circuit of the protective circuit grounding... This fully applies to gas boilers.

A reliable system is one of the most important requirements. grounding all metal parts of gas equipment, potential equalization between them and other pipelines and metal structures.

Installation (assembly) of a special additional system grounding.

It is well known that for the reliable functioning of all household appliances in the house, one protective circuit is sufficient. grounding... If a special add-on system is installed grounding for a gas boiler, then it must be connected to the main element grounding, and the boiler and pipes must be connected to the potential equalization system (PFC).

To this system of protective grounding all conductive materials must be connected, for example: frames plasterboard partitions, plumbing fixtures and pipes, as well as any metal housing of household appliances used in the house. This undoubtedly also applies to gas equipment.

It is imperative to remember that the gas inlet pipe must be connected to the potential equalization system of the structure grounding a special conductor with a cross section of at least 4 sq. mm. For a gas boiler, one grounding conductor is sufficient, which is included in the wire. If the boiler has a separate terminal for the safety circuit grounding, it should also be connected to the SPC.

If you don't make the system grounding for gas equipment, the following consequences are possible.

When performing electrical work, an equipotential bonding box of the protective system should also be provided. grounding in the boiler room, if one is supposed to be in the project, and also bring the grounding conductor from the shield to the place where the gas pipe is injected. Moreover, such a conductor grounding must have an appropriate cross-section.

Installation instructions for the structure grounding for gas equipment.

Before starting the main work, you need to take care of creating an independent outer contour. grounding close to the building.

Shrinkwrap grounding is performed in the following order:

As a protective circuit grounding it is recommended to use natural grounding conductors, for example, water and other metal pipes - sewage and central heating pipes or wells, metal or reinforced concrete structures of buildings and other structures in contact with the ground. These structures can be bent by welding to provide the required joint cross-sectional area. In this case, the grounding conductor of the structure grounding there can be strip steel with a cross section of at least 48 sq. mm with a thickness of 4 mm or a steel corner with a shelf thickness of at least 2.5 sq. mm. During the installation of the protective circuit grounding for a gas boiler, you should follow the instructions and requirements of the electrical laboratory and gas service.

It is imperative to consult with highly qualified and experienced specialists, since the existing regulatory documents and grounding act / protocol resistance measurements grounding sometimes very contradictory or inaccurately expresses all the requirements for the installation of a protective circuit grounding... For example, a clear point about the need to install an additional protective circuit grounding, when connecting the gas supply to an individual residential building, not in a single document. Perhaps this requirement should be looked for in the territorial regulations.

When installing a gas boiler, the main thing is to ensure the safe operation of this vital device. If all the rules and regulations are observed, gas services will issue all Required documents and permits without unnecessary red tape, and will be issued grounding act/ protocol resistance measurements grounding.

Before putting the facility into operation and after carrying out the entire range of necessary electrical work, the new electrical system needs to be tested for operability, reliability and safety. During such studies, specialists check all elements of the system, including the system of the protective circuit. grounding ensuring its functionality and guaranteeing its safe use by residents of the house or employees of the enterprise.

Based on the results of the research, the checking specialists draw up a package of documents containing Actgrounding/

protocol contour measurements grounding and another necessary Act confirming the safety of the network and allowing the use of the electrical system of the facility by people.

The principle of protective grounding.
Protective action grounding based on the following principles.

Reduction to a safe value of the potential difference between the grounded conductive object and other conductive objects that have a natural grounding.
Leakage current drainage when a grounded conductive object comes into contact with a phase conductor. In a properly designed system, the appearance of a leakage current leads to an immediate trip of protective devices (RCDs).

In this way, grounding it is most effective only in combination with the use of residual current devices. In this case, with most insulation violations, the potential on grounded objects will not exceed safe values. Moreover, the faulty section of the network will be disconnected within a very short time (tenths ... hundredths of a second - the RCD trip time).

System operation grounding in case of malfunctions of electrical equipment.

A typical case of electrical equipment malfunction is the phase voltage hitting the metal case of the device, which means that a person can also get under voltage due to insulation failure.

Depending on what protective measures are implemented, and most importantly, how the circuit of the protective grounding electrical equipment, the following options are possible.

The case is not grounded to the protective circuit. grounding, There is no RCD (the most dangerous option).
The body of the device will be at phase potential and this will not be detected in any way. Touching such a defective appliance can be fatal.
The body is connected to the loop grounding, There is no RCD. If the leakage current in the phase-housing-grounding circuit (design grounding) is large enough (exceeds the threshold for the fuse protecting this circuit), then the fuse will trip and cut off the circuit. The highest effective voltage (with respect to ground) on a grounded housing will be Umax = RG · IF, where RG is the resistance of the ground electrode, IF is the current at which the fuse that protects this circuit is triggered. This option is not safe enough, since with a high resistance of the circuit grounding and with large fuse ratings, the potential on an earthed conductor can reach quite significant values. For example, with a grounding resistance of 4 ohms and a 25 A fuse, the potential can reach 100 volts.
The body is not connected to the protective circuit grounding, The RCD is installed. The body of the device will be at phase potential and this will not be detected until there is a path for the leakage current to flow. In the worst case, leakage will occur through the body of a person who touches both a faulty device and an object that has a natural ground. The RCD disconnects the faulty section of the network as soon as a leak occurs. A person will receive only a short-term electric shock (0.01 ÷ 0.3 seconds - the RCD response time), which, as a rule, does not cause harm to health.
The body is connected to the loop grounding, The RCD is installed. This is the safest option, since the two protective measures are mutually complementary. When the phase hits
voltage to a grounded conductor - current flows from the phase conductor through an insulation fault into the ground conductor of the loop grounding and further into the ground. The RCD immediately detects this leak, even if it is very insignificant (usually the sensitivity threshold of the RCD is 10 mA or 30 mA), and quickly (0.01 ÷ 0.3 seconds) turns off the section of the network with a malfunction.

In addition, if the leakage current is large enough (exceeds the trip threshold of the fuse protecting this circuit), then the fuse may also blow. Which protective device (RCD or fuse) will disconnect the circuit depends on their speed and leakage current. It is also possible for both devices to be triggered.

Sign protocol (grounding act) measurements resistance grounding…

Issue a passport for the protective circuit grounding, and therefore carry out all the necessary electrical measurements, tests of grounding devices and grounding electrodes, as well as draw up and sign protocol (grounding act) resistance measurements grounding only a certified electrical laboratory that has all the necessary permits is eligible.

Registration of an electrical laboratory.

Many are interested in the question: is it necessary for an electric laboratory to join an SRO? Of course, yes. The point here is this: when putting new electrical equipment into operation, after accidents, during operation, it is necessary to carry out appropriate measurements, after which a special grounding act/ protocol resistance measurements grounding.

To issue grounding act/ protocol resistance measurements grounding can only that ETL, which has been registered with the bodies of Rostechnadzor, where it received permission to carry out certain measurements.

Rostechnadzor issues a certificate of registration of the electrical laboratory at its legal address. It is valid for three years absolutely throughout Russia. After its completion, each electrical laboratory is interested in its extension.

The procedure for reissuing an electrical laboratory is completely similar to registration. The manager collects all the necessary documents and submits them to Rostekhnadzor for verification.

What is an electrical laboratory?

An electrotechnical laboratory is a modern electrotechnical organization that provides a certain range of services related to electrical measurements of the entire electrical network, as well as systems grounding in offices, production facilities, shopping centers, houses and apartments.

She can carry out various types of work aimed at checking any equipment, which is powered from the network, and at the end of the checks, an ETL specialist will issue protocol(Actgrounding) checking the circuit of the protective grounding.

The electrical laboratory is unified system, which measures the resistance of the protective circuit grounding, which includes:

The electrical laboratory must be registered with Rostekhnadzor. Only under this condition the company is allowed to issue protocol (Act) tests and draw up and issue grounding act /protocol resistance measurements grounding other organizations. Registration of the laboratory is not required only for those organizations that do not draw up technical reports and do not issue relevant acts, including grounding act /protocol resistance measurements grounding other companies.

Also, according to PTEEP, there are certain requirements for the personnel who measure the resistance of the protective circuit grounding... Specialists must have the necessary knowledge, confirmed by tests, the right to carry out such studies and an appropriate group for electrical safety.

It should be noted that the PUE clearly states that, in accordance with the existing regulatory and technical documents, the instructions of the manufacturing plants and the current standards, the acceptance measurements made by the personnel grounding preceding the direct commissioning of electrical equipment must be accompanied by correctly drawn up protocols and acts, including - grounding act /protocol resistance measurements grounding.

Resistance of the grounding device and protocol (grounding act) checking the insulation resistance of the structure grounding.

Resistance value grounding, should not exceed the permissible resistance value, for different types systems grounding... These values are indicated in PUE 1.7.101 (7th ed.). Standards SO-153-34.21.122-2003, RD.34.21.122-87 prescribe regulatory values for devices
lightning protection. In electrical installations, the protective circuit grounding and grounding provide protection of people from electric shock when touching metal non-conductive parts, may be energized as a result of damage to the insulation.

Protective contour grounding is made for metal parts of electrical installations that are accessible to human touch and do not have other types of protection.

Structural resistance test grounding/ contour of the grounding.

Resistance test grounding and grounding devices - carried out in accordance with the normative technical documentation PUE 1.7.101 (7th ed.), Standard SO-153-34.21.122-2003, RD.34.21.122-87, which prescribes standard values for lightning protection devices.

So, the bodies of electrical machines, transformers, lamps and other non-current-carrying parts can be energized when short-circuited to the body. If the housing is not connected to the safety circuit grounding, then touching it is as dangerous as touching the phase. When the body is grounded, the current through the human body, when it touches the body, will be the less, the less the earth fault current and the resistance of the structure circuit grounding, and the closer a person is to the ground electrode.

Earthing device / circuitgrounding is a set of conductors and grounding conductors. Earthing switch or protective circuitgroundingis a conductor or a collection of metal bonded conductors in contact with the ground, which are connected to the bus grounding.

Measuring the insulation resistance of elements grounding.

Equipment cable conductors grounding separated by a special insulating sheath. With the optimal version, its resistance reaches infinity. But in practice, the opposite is true. When a voltage is applied between such conductors, an electric current is generated, which is called a "leakage current". In the event that the insulation coating of the wires is broken, then this can provoke a short circuit and - as a result - lead to a fire. But if you carry out timely control, measure the insulation resistance of the electrical wiring of the elements grounding, then this will avoid serious consequences.

Insulation quality of elements grounding, determines the degree of safety in the operation of power grids and electrical equipment. An important indicator that determines its integrity and the degree of deterioration is insulation resistance. Therefore, any inspection of the condition of the insulation involves the measurement of this characteristic. The frequency of such inspections is determined by the regulations of Rostekhnadzor, the Ministry of Emergencies and other regulatory bodies.

There is the following frequency of insulation measurements:

at hazardous production facilities and in outdoor electrical installations, insulation resistance measurements are carried out at least once a year;
in office and residential buildings every three years.

The result of the work of the electrical laboratory after the tests and measurements is the preparation of a document on the results of the work - protocol (grounding act) resistance measurements grounding... This document contains the results of measurements, the design of each of which has a strictly defined form about the compliance of the measured results with the requirements of the corresponding normative documents.

The result of the work of the electrical laboratory may be a technical report containing protocol (grounding act) measuring the resistance of the circuit grounding.. Also, the report can be presented as a single protocol (Act) with measurement readings for each type of work on measuring resistance grounding... However, this does not change the basic requirements for the presentation of the results. For the convenience of the description, we will focus on the first option - registration of the completion of work on checking the elements grounding in electrical installations in the form of an act / protocol per system grounding in the technical report on electrical measurements and as a result - electrical equipment EARTHED.

According to the results of resistance measurements grounding…

If the resistance measurement results grounding do not correspond
standard indications, then the soil resistivity is measured.
If the measured value is within acceptable limits, then the number or length of vertical elements can be increased. grounding.
If the resistance is unsatisfactory grounding is the result of high soil resistivity, it may be decided to use devices grounding with an increased resistance value.

In some cases, the defect "increased resistance grounding»Can be corrected using special chemical compositions designed to reduce soil resistivity.

Drawing up a technical report.

Technical report after measuring system resistance grounding Your home or other building always starts with title page... The logo of the company and the details of the electrical measuring laboratory are indicated on it. The name of the customer's organization, the full address and the name of the object are also indicated. The date of the measurements of the resistance of the system is mandatory. grounding and printing of an electrical laboratory.

Following the title page in the technical report measuring the resistance of the system grounding there is the content, and for the protocol of acceptance works, it is followed by the passport of the object, where the customer, the address and name of the object are duplicated, as well as links to the project of the electrical installation, the design organization, the conditions and purposes of testing the system grounding.

In the event of violations in the electrical installation of the facility, after testing and measuring the resistance of the protective circuit grounding a specialist of the Pushkin Energy and Gas Company will issue a statement indicating all defects, and recommendations for their elimination, and after their elimination is issued Act grounding /protocol resistance measurements grounding.

An experienced electrician will carry out any work on the replacement of elements grounding, as well as for connecting electrical appliances.

Test objectives (measurements)

The purpose of the tests is to verify the compliance of the grounding device with the requirements of PUE-7 Ch. 1.7, clauses 1.8.39 (1,2,5), clause 1.8.40 (12), standards of the GOST R 50571 complex, GOST R 50571.16-2007 Clause 612.6.2, PTEEP Ch.2.7, Appendix 3 Clauses 6.5, 26.1, 26.3, 26.4 and design documentation, compliance with which ensures the required electrical and fire safety of electrical installations and electrical equipment, the safety of the population and service personnel, as well as reliable operation of electrical equipment and electrical installations when used for their intended purpose.

Types of tests (measurements)

When checking the grounding device, the following types of tests are performed:

Acceptance - control tests during acceptance control.

Periodic - control tests carried out in the volumes and within the terms established by the normative and technical documentation, in order to control the stability of the quality of electrical equipment and the possibility of its further use.

Operational - tests of the facility carried out during operation in accordance with the requirements of PTEEP clause 3.6.2:

K - tests and measurements of parameters at overhaul electrical equipment;

T - tests and measurements of parameters during the current repair of electrical equipment;

M - overhaul tests and measurements, i.e. preventive tests not related to the withdrawal of electrical equipment for repair.

Scope of experiments

After the installation of grounding devices, before backfilling, an act for hidden work and an act of inspection and verification of openly laid grounding conductors are drawn up.

Additionally, a passport is drawn up for the charger, which should contain a grounding diagram, basic technical data, data on the results of checking the state of the charger, on the nature of repairs and changes made to this device.

The tests are preceded by the study of the design documentation, the ZU passport (lightning protection passport), acts of hidden work, a thorough examination. ZU rejected during external examination, regardless of the test results. replaced or repaired.

In accordance with clause 612.6.2 of GOST R 50571.16-2007, during the tests, the resistance of the ground electrode must be measured.

Measurement of the resistance of the ground electrode where it is required according to GOST R 50571.3, p.411.5.3, relative to TT systems, according to GOST R 50571.3, p. 411.4.1, with respect to TN systems and GOST R 50571.3, p.411.6.2, in relation to IT systems, is carried out by an appropriate method.

Notes (edit)

An example of a measurement method using two auxiliary ground electrodes is given in Appendix C (methods 1 and 2) GOST 50571.16-2007.
Where in the TT system the location of the electrical installation is such (in the city) that it is virtually impossible to ensure the presence of two auxiliary grounding electrodes, the measurement of the impedance (or active resistance to spreading) will result in an overestimated value.

When testing in accordance with PUE-7, clause 1.8.39 (1,2,5), grounding devices are tested in the volume and the following sequence:

Checking the elements of the grounding device. It should be done by inspecting the memory elements within the scope of inspection. The cross-sections and conductivity of the elements of the grounding device must comply with Chapter 1.7 of the PUE-7 and design data.

Checking the circuit between grounding conductors and grounded elements. The cross-sections, integrity and strength of the grounding conductors, their connections and connections are checked.

Measurement of resistance of grounding devices. The resistance values must comply with the values given in the corresponding chapters of the PUE.

When carrying out operational tests, the charger is tested in the volume determined by PTEEP Chapter 2.7. Appendix 3.

In accordance with PTEEP clause 2.7.8, to determine the technical condition of the grounding device, visual inspections of the visible part, inspections of the grounding device with selective soil opening, measurement of the parameters of the grounding device in accordance with the standards for testing electrical equipment (PTEEP Appendix 3)

In accordance with PTEEP clause 2.7.13, to determine the technical state of the charger in accordance with the standards for testing electrical equipment (PTEEP Appendix 3), the following should be performed:

- measurement of the resistance of the grounding device;

- checking the presence of a circuit between the grounding device and the grounded oneselements, as well as connections of natural grounding conductors with grounding device;

- measurement of loop resistance phase-zero, checkfuse conditions;

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

Checking the connections of ground electrodes with grounded elements, including natural ground electrodes - revealing breaks and other defects by inspection, tapping with a hammer and measuring transient resistance.

Checking the condition of the elements of the grounding device located in the ground:

electrical installations, except for overhead lines - inspection of the elements located in the ground, with the opening of the soil, is carried out selectively, the rest - within the scope of inspection; in the closed switchgear, the inspection of ground electrodes is carried out by the decision of the technical manager of the Consumer;
VL - random inspection with soil opening is carried out for at least 2% of the total number of supports;

Measuring the resistance of the grounding device:

poles of overhead lines up to 1 kV - produced on all poles with lightning protection earthing switches and repeated neutral conductor earthing switches. For the rest of reinforced concrete and metal supports, it is made selectively for 2% of the total number of supports;
electrical installations, except for overhead lines.

Measuring the resistivity of the earth.

Power grounding control cable lines is performed by measuring the grounding resistance of end couplings and terminations in accordance with Section 26 (PTEEP Appendix 3, Section 6.5). Grounding must be done in accordance with Chapter 1.7 of PUE-7.

Test sequence (measurements)

Each electrical installation during installation and / or after it, prior to commissioning, must be inspected and tested in order. to make sure as far as possible that the requirements of the standards of the G OST ’R 50571 complex, PUE, PTEEP and the project are met.

After a visual inspection, tests are performed to check the memory.

Test procedure (measurements)

The test procedure is given in the MVI "Checking the grounding device".

Test conditions (measurements)

When checking the condition of the elements of the overhead line grounding device, the inspection with the opening of the soil of the surveys, the opening of the soil is repeated on the neighboring supports of the overhead line until satisfactory grounding is found on two in a row in the same direction of the supports. After precipitation, landslides or swelling of the soil in the zone of the grounding device, extraordinary inspections with soil opening should be carried out.

When checking the state of the memory elements, inspection of the elements located in the ground, with the opening of the soil, is carried out selectively, the rest are within the scope of inspection.

Before taking measurements, it is necessary to reduce the number of factors that cause additional error: install the meter almost horizontally, far from powerful power transformers, drive the electrodes strictly vertically, knock out the direction of the electrode spacing so that the connecting wires do not pass near the metal structures and parallel to the NEP route, while the distance between the current and potential wires. not less than 1 m, measurements should be carried out according to a four-clamp scheme, etc.

Earth resistance meter F4103-1M designed for operation at an air temperature from -25 to + 55 ° С and relative humidity up to 90% at a temperature of + 30 ° С.

Earth resistance meter IS-20 corresponds to group 4 in accordance with GOST 22261. Operating conditions of the device: temperature from -15 to + 50 ° С, relative humidity up to 90% at + 30 ° С. Normal conditions according to GOST 22261: air temperature from +15 up to + 25 ° С; relative humidity 30-80%; atmospheric pressure 84-106 kPa (630-795 mm Hg).

When determining the resistivity of the soil in the places where the rod of the auxiliary grounding conductor and the probe are driven, the vegetation or bulk layer must be removed.

The measurement of the resistance of the charger should be carried out during the periods of the lowest soil conductivity, g.u. with the greatest freezing of the soil and in dry summer time with its greatest drying.

Requirements for grounding electrodes in soil and soil resistivity in accordance with Appendix D of GOST R 50571.5.54-2013:

The resistance of the grounding electrode depends on its size, shape and resistivity of the pear into which it is buried. This resistivity often varies in length and depth.

Soil resistivity is expressed in Ohms - the resistance of a cylinder with a base cross-sectional area of 1 m 2 and 1 m long.

The nature of the surface and vegetation can give some information on a more or less favorable soil characteristic for installing a ground electrode system. More reliable information is provided by the availability of measurements on grounding electrodes installed in such soil.

Soil resistivity depends on moisture and temperature, both of which change throughout the year. Moisture - under the influence of soil granulation and its porosity. In practice, soil resistivity increases with decreasing moisture.

Soils in flooded areas of rivers, as a rule, are not suitable for the installation of grounding conductors. These soils are composed of a stone base, are highly permeable and are easily flooded with filtered water of high resistivity. In this case, depth electrodes must be installed in order to reach deeper soil layers, which may have better conductivity.

Frost significantly increases soil resistivity, which can reach several thousand ohms in a frozen layer. The thickness of this frozen layer in some areas can be one meter or more.

Drought also increases soil resistivity. The drought effect can be observed in some areas up to a depth of 2 m. The resistivity values under such conditions can be of the same order of magnitude as during frost.

Table D.54.1 of GOST R 50571.5.54 gives information on the values of resistivity for certain types of soil.

Table D.54.1 - Resistivity

Characteristics of the soil	Resistivity, Ohm
Swampy land	1 ohm to 30
Alluvium	20-100
Humus	10-150
Wet peat	5-100
Soft clay	50
Lime clay and compacted clay	100-200
Jurassic marl	30-40
Clay sand	50-500
Siliceous sand	200-3000
Bare stone soil	1500-3000
Stony soil covered with meadow	300-500
Soft limestone	100-300
Compacted limestone	1000-5000
Porous limestone	500-1000
Crystalline shale	50-300
Crystalline shale with mica	800
Granite and sandstone according to the weather	1500-10000
Granite and heavily altered sandstone	100-600

From table D.54.2 of GOST R 50571.5.54 it can be seen that the resistivity can vary significantly for the same type of soil. As a first approximation, the resistance can be calculated using the average values of table D.54.2 of GOST R 50571.5.54.

Table D.54.2 - Change in resistivity for different types soil

Obviously, calculations made on the basis of only these values give a purely approximate value of the resistance of the grounding electrode. Applying the formula given in section D.3 of GOST R 50571.5.54, the measurement of resistance makes it possible to estimate the average value of soil resistivity, which can be useful for further work performed in similar conditions.

Grounding electrodes buried in the ground can be made from (Appendix D.3 GOST R 50571.5.54-2013):

hot-dip galvanized steel,
steel in a copper sheath,
copper-plated steel,
of stainless steel,
bare copper.

Connections between various metals should not be in contact with soil. Other metals and alloys should not be used.

Minimum thicknesses and diameters of parts are assumed for normal risks of chemical and mechanical aging. However, these dimensions may not be sufficient in situations where there are significant risks of corrosion. These risks can be encountered in soils where stray currents propagate, for example DC return currents in electric traction circuits or near cathodic protection installations. In this case, special precautions must be taken.

Grounding electrodes should be buried in the wettest parts of the ground. They should be located away from landfills where filtration, such as excrement, is possible. liquid fertilizers, chemical products, coke, etc., which can corrode them and are located as far as possible from busy places.

Place of testing (measurements)

The place of testing is the grounding devices of electrical installations and cable lines.

Terms of testing

Electrical equipment of low-voltage electrical installations re-commissioned (during installation and / or after it, before commissioning) must be subjected to acceptance tests in accordance with GOST R 50571.16-2007 and PUE-7 Ch.1.8.

Periodic inspection and testing of the EI is carried out in order to determine whether the state of the EI or its part has deteriorated so much as to pose a danger during operation, and whether they comply with the current ND. Additionally, it is necessary to check whether the conditions of use of the premises have changed compared to those for which the power plant was intended.

NOTE The information required for acceptance testing is also valid for periodic inspection and testing.

The interval between periodic inspections and tests of an electrical installation is determined in accordance with the type of electrical installation and electrical equipment, its operation and operating mode, the quality of electrical energy of the supply network, the interval and quality Maintenance, as well as environmental conditions.

Periodic tests of electrical installations are carried out at a minimum time interval.

Notes (edit)

The minimum time interval for testing is determined by the consumer of the electrical installation.
This time interval can be set, for example, once every two years, with the exception of the following cases, in which there may be more high risk, which requires a shorter period of time between inspections and tests:
in the presence of workplaces and areas in which there is a risk of deterioration in the quality of the installation, fire or explosion:
in the presence of workplaces and an area where both low and high voltage is present;
in the case of using communal electrical installations;
for construction sites;
for areas where portable equipment is used (e.g. emergency luminaires).
For residential premises, intervals between inspectionsmay increase.
When the operating conditions of the living quarters change, it is necessary to carry outchecking the state of the plant.
In the absence of a previous periodic test report, additional tests are carried out.

Table 4 Nomes for testing electrical equipment and devices for electrical installations of consumers in accordance with PTEEP - K, T, M are performed within the time limits established by the PPR system

Test name	Test type	Test standards	Directions
Power cable lines
6.5. Measurement control	TO	Manufactured in accordance with section 26	Produced by metal. end sleeves and terminations of cables with voltage higher than 1 kV.
Grounding devices
26.1 Checking Connections earthing switches with earthed elements, including local earthing switches	K, M	Verification is carried out to detect breaks and other defects by inspection, tapping with a hammer and measuring transient resistance. Checking the connection with natural earthing electrodes is carried out after the repair of the earthing electrodes.	In the case of measuring contact resistances, it should be borne in mind that the resistance of a good connection does not exceed 0.05 Ohm. At cranes, the presence of a chain should be checked at least once a year.
26.3 Checking the state of the charger elements located in the ground: 1) electrical installations, except for overhead lines 2) VL	M	Corrosion check is carried out at least 1/12 liter. replaced if more than 50% of its section is destroyed. Checking of ground electrodes in outdoor switchgear of power stations and substations is carried out selectively, in places most susceptible to corrosion, as well as near places of grounding of the neutral of power trans-drov, connections of arresters and surge arresters. On overhead lines, a spot check with soil opening is carried out for at least 2% of the supports from the total number of supports with grounding conductors.	In the closed switchgear, inspection of the elements of grounding conductors is carried out by the decision of the technical manager of the Consumer. Checking should be carried out in populated areas, in areas with the most aggressive, blown out and poorly conductive soils.
26.4 Measurement of earthing device resistances 1) supports of overhead power lines (VL) 2) electrical installations, except for overhead lines	K, T, M K, T, M	The value of the resistances of the earthing switches of the supports are given in Table 35 Appendix 3.1 PTEEP The values of the resistances of the memory of electrical installations are given in table 36 app. 3.1 PTEEP	It is produced after repairs, but at least once every 6 years for overhead lines up to 1 kV and 12 years for overhead lines above 1 kV on supports with arresters, etc. terrain. Measurements are also carried out after the reconstruction and repair of the memory, as well as upon detection of destruction or traces of overlapping of insulators by an electric arc.

In accordance with PTEEP clause 2.7.13, measurements should be carried out during the period of the greatest drying out of the soil (for permafrost regions - during the period of the greatest freezing of the soil).

Provision of tests (measurements)

When performing the tests, the following measuring instruments and auxiliary devices are usedTable 5

SI name, auxiliary devices	SI type designation	Factory. Number*	Metrological specifications	Measured value designation
1	2	3	4	5
Earth resistance meter	F 4103-M1		Limits of permissible basic error of error + 4% in the range of 0-0.3 ohms; + 2.5% on other bands. Range .: 0-0.3; 0-3-10-30-100-300-1000-3000-15000	Resistance of the charger.
Earth resistance tester with accessories set, with clamp	IS-20/1 KTI-20/1	n / a	1.00 to 999 mΩ; 0.01 to 9.99 Ohm; from 0.1 to 99.9 ohms; from 1 to 999 Ohm; from 1.00 to 9.99 kΩ;	Resistance of the charger. Soil resistivity
Calipers	SHTs		150 mm, + 0.1 mm	Measurement of cross-sections
NTD	Deviation from the project d.b. agreed with the design organization			Visual inspection

* see list of SI

The electrodes must be cleaned of paint, and at the points of connection of flexible wires and from rust.

Test reporting (measurements)

After tests in accordance with 61.1.1 and 61.1.4 of GOST R 50571.16-2007, a protocol is drawn up.

Test results: the characteristics of the charger, the results of external examination of the visible part of the ground electrode, the results of a random check of the grounding device located in the ground, the condition of the soil and the value of the correction factor, the results of measurements of the resistance of the grounding device, taking into account the correction factor of the soil resistivity, are entered into the protocol drawn up in accordance with with the requirements of GOST R 50571.16-2007 Appendix H.

Responsibility for providing tests (measurements)

Responsibility for the provision of tests is assigned to the head of the electrical laboratory in accordance with the Regulations on the electrical laboratory and (or) other persons who, in accordance with the orders of the management of the enterprise, are responsible for ensuring the tests.

For violations in the provision of tests, responsibility is imposed on the head of the electrical laboratory in accordance with the law of the Russian Federation "On ensuring the uniformity of measurements", Section 6, Article 25: "Legal entities and individuals, as well as state governing bodies Russian Federation those guilty of violating the provisions of this Law bear criminal, administrative or civil liability in accordance with the current legislation "

Responsibility for conducting tests (measurements)

Responsibility for testing is assigned to the head of the electrical laboratory in accordance with the Regulations on the electrical laboratory and (or) other persons who, in accordance with the orders of the management of the enterprise, are responsible for testing.

For violations in the conduct of tests, employees bear criminal, administrative or civil liability in accordance with the current legislation.

The main task solved by visual inspection of grounding systems is to find out their current state and compliance with technical and operational standards. At the same time, according to the current regulations, openly laid grounding conductors can be subjected to a more thorough check, including a partial opening of the soil near the bus.

Inspection objectives and standardized indicators

In some cases (in accordance with the approved schedule or by the deadline determined by a special order of the head of the unit), the parameters of the contour are measured in order to find out the degree of their compliance with the standardized values.

The procedure and frequency of inspection of open grounding sections are regulated by the PTEEP requirements, as well as by a number of building codes related to their arrangement.

On the basis of the above regulatory documents, those intervals are established, taking into account which the open parts of the system and the ground electrode system are examined for any visually distinguishable damage.

In addition, the current regulations stipulate a number of technical points that must be paid attention to during the course.

These include, in particular, an assessment of the current state of the protective coating of tires, as well as inspection and quality control of welded and bolted joints.

The timing and procedure for conducting surveys

Specific terms for checking the state of the AP (bus wiring and ground loop) are included in the PPR schedule approved by the technical manager of this facility.

According to clause 2.7.9. PTEEP visual inspection of open sections of the system should be carried out at least once every six months.

Similar inspections, involving partial sampling of soil in the area of open places, are organized at least once every 12 years.

During visual inspections of sections of the ground loop, the following are subject to mandatory check:

the condition of the contact and welded joints between the individual components of the grounding system (the grounding conductor itself, connecting strips and the equipment in use);
the integrity of the layer of anticorrosive protective coating of grounding;
absence of any breaks in the bus circuit.

Based on the results of the survey, an act is drawn up on the current state of the object and its grounding circuit. And all the data obtained in this case must be entered into the passport of the device under test.

Periodic inspections with partial opening of the soil near the grounding of neutral conductors of power devices, connections of arresters and surge arresters are also carried out in accordance with the PPR schedule. By analogy with the usual open sections of the track, these places should also be checked at least once every twelve years.

Requirements for exposed wiring of grounding conductors

According to the current technical regulations, in which the requirements for the arrangement of the grounding circuit are specially stipulated, the protective conductors inside the premises and within the outer spaces can be laid openly.

This method of mounting them allows you to periodically monitor the condition of individual tires and provides partial access to adjacent areas hidden in the ground.

This requirement does not apply to the so-called "zero" grounding conductors, as well as cables in an armored or steel sheath. It does not apply to grounding PE wires deliberately laid in ducts or metal pipes, or in niches hidden in the walls.

pad

The grounding busbars are laid only horizontally or only vertically, and in the presence of inclined structural elements - parallel to them.

In rooms with low humidity levels, such tires can be mounted directly on a brick or concrete base. In this case, the rigid fixation of the steel strips is carried out by means of special fasteners (dowel-nails).

In rooms classified as "damp" or "very damp", as well as containing corrosive fumes, the earthing conductors to be installed will need a special lining in the form of supports at least 10 millimeters apart from the base.

The step of fastening steel strips should be of the order of 0.6-1.0 meters in straight sections of the laying and approximately 0.1 meters when bending the route in the places of its branches.

The height relative to the floor is chosen equal to 0.4-0.6 meters, and the distance from the removable floors of cable channels should not be less than 50 millimeters.

Through the ceiling and wall partitions, grounding conductors are laid in specially designed openings with protective sleeves.

Dyeing

Openly placed protective earthing conductors are painted in such a way that, if desired, they can be easily distinguished from other conductive elements. When inspecting the ground, the coloring helps to quickly identify the object of the test.

Those places of the grounding buses that are intended for connection to other elements of the system and are not subject to painting.

According to the requirements of the PUE, the remaining places of such tires should be painted in a combined green-yellow color (green background with a yellow stripe applied along the conductor).

Joint

When inspecting the grounding, the connections of the elements are checked. The articulation of grounding buses and their fastening to metal structures should be carried out for welding, with the exception of separate detachable places used to connect measuring instruments.

The dimensions of the overlapping zone of the plates at the junction points are made equal to the width of the conductors (in the case of their rectangular shape) and six diameters in the case of a cylindrical bus.

Grounding bars are connected to the housings of electrical equipment using a special bolt on their base. Cases of stationary electrical devices mounted on special skids are grounded by connecting a protective bus on their moving parts.

When working in conditions of strong vibrations that weaken the place of attachment of electrical equipment, special measures are required to prevent this process (use of locknuts, lock washers, and so on).

The contact zones of the conductors and sections of the serviced units at the points of their bolted joints are thoroughly cleaned until a metallic sheen is formed. Upon reaching the required smoothness of the contact pads, the latter are covered with a layer of special technical grease.

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