Zahisne grounding appointment. Zahisne grounding

⁰

The concept of zahisnogo grounding is the principle of yoga diy. The purpose of grounding is to prevent the safety of electric jet damage at the razor dot to the hull. Grounding survey is carried out for admissible stresses dotik and kroku or admissible support roztіkannya strumu zemlyuvacha. Roofing of grounding can be set on the basis of the main parameters of grounding - the number of vertical grounding conductors and the order of placement of grounding conductors and grounding conductors and yogo crossing.

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71. The concept of zahisnogo grounding is the principle of yoga diy.See grounding outbuildings.

Zahisne grounding - navmisne electrical installation from the ground of metal non-current-carrying parts,yakі can opine under the strain of zamikannya on the body. Purpose of grounding- Usunennya nezabezpeka razhennya elektrostrumu at razі dotik to the hull.

Just like vikonan grounding zdatne protect people from unsafe shock electric jet and take care of the superb work of the outbuildings. Grounding attachments, recognized for the navmisny electric connection from the earth, the possession of that electrical installation, or the connection of any point of the fence. grounding consists of two main parts:

∙ grounding- metal electrodes at the sight of steel(Ridshe midny) haircut, hammered vertically into the ground; can buti representations as a complex of elements special form.

∙ grounding conductorszahisnі conductors, what to eat grounding extension from grounding.

Rozrahunok of the grounding outbuildinglead up to the appointed number,type and place of placement of grounding devices,as well as cutting ground conductors.Rozrahunok of the grounding outbuilding to ensure the insurance of life factors,what to pour into the earthing ground.Tse to finish the folding process.which can vikonati nadіyno and professionally less fahіvets,Volodymyr the necessary certificate and novice.

Rozrahunok groundingbe carried out behind an allowable pressure dot and a crock or an allowable support for the earthing jet.Rozrahunok groundingmaє on me install the main parameters of the grounding- The number of vertical grounding devices and їх expansions,order of placement of grounding devices,dozhini grounding conductors and їх peretina.

Attachment groundingmaє obov'yazykovo vіdpovіdati all vіmogam main document of the Russian Federation"PEU" ( rules for the installation of electrical installations) .

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Zahisne grounding- the price is not electrically grounded from the ground, or it is the equivalent of metal non-current parts, which can be supported by a voltage. Serve to change the hum to the body of the hum to the ground with the method of changing the voltage on the hull above the ground to a safe value.

ground- means metal overhead, for additional wires, which do not wash insulation, or tires, grounding elements from grounding elements, or parts of the possession, which zahistu. Grounding workers are natural and piece.

Natural grounding- metal objects that can be enough to permanently cover the surface with the ground (pipelines, structural elements of buds, tanks for water).

Piece grounding- be it metal objects, which can be sufficient for that permanent surface of the earth, which are specially laid in the ground for the purpose of grounding (pipes, coils, profiles, rods).

Natural and piece earthing machines are grounded one by one with a metal steel tire, overpassed by the values of the strums of earthing on the ground and mechanical earthing machines.

A grounding conductor is called a wire, which is possessed, which is protected by a grounding conductor, which is found in the earth.

The density of the grounding is determined by the value of the grounding support and the change in the voltage of the earth. Under the support of the grounding grounding, the grounding is rozumіyut opіr mіzh grounding (bіlya mіstsya zіtknennya іz ґrunt) that earth. The value of the grounding support is determined as a reflection of the new voltage of the earth up to a new strum earth murmur. Under the full tension of the earth, there is a tension that is due to the lance, the struma of the earth between the grounding that earth (zero potential zone).

The physical nature of the grounding is shown a little, de livoruch is depicted as a three-phase electrical receiver (electric motor, transformer, attachment), the right-hander is the source of electricity, the neutral of which is tightly grounded. On this little one, there is a presence of a change in the voltage U and L de L - between the ground and the zone of zero potential.

Schematic diagram grounding for protection from the voltage, which is vinyl on the body of the valve. 1 - electric receiver; 2, 3 - grounding; 4 - dzherelo elktroenergії; z chol - the last opir of the body of a person; U p - total voltage of the earth; U pr - voltage dotik; U krok - the voltage of the krok; r- active opir insulation; s - the capacity for the goodness of the earth.

If the insulation of the electrical receiver failed, then the jet-carrying part was electrically connected to the ungrounded metal housing of the technologically equipped or zahisny outbuilding. Having bumped into such a body, or under the yogic construction, grounded without grounding, a person appears under an elastic dot, the meaning of which is similar to the phase one, or close to new. In such a rite, the day of the day, for the help of the building, to ground the ground, the creation of such grounding, as if it were not enough to rely on, to do little, so that the fall of the voltage on the new (and it itself will be hostile) does not reach the value that is not safe for the people. It is necessary for a poor lancer to secure such a significant struma, as if it would be sufficient for a good practice zahisnih outbuildings, installed on the lifeline.

Normalization of the grounding support. For a voltage limit lower than 1000, on the basis of statistical data, the "Rules for the construction of electrical installations" indicate only the upper numerical value of the permissible inter-ground support, and itself 40 m.

6. Zeroing(Grounding system with zero grounding wire).

Zanulennyam it is called zahisniy zakhid, which zastosovuetsya only in the merezhy from the grounded neutral voltage below 1000 V metal parts possession, which is not normally known, but they can opine under the strain at quiet chi and other poor isolation, and lie at the edge of the strum, which is sufficient for the nadiya robot of the zakhist.

Zanulity- tse means metal (electrically) superficially from the last parts of the possession, which swear by the zakhist, zero dart. Zanulennya vymagaє zastosuvannya zemlyuvachiv for priednannya to them zero drotu. Ale, the meaning of these groundings is more, lower grounding.

The principle scheme of zeroing the zahistu of people in the form of tension, which is to blame on the body of the possession in case of poor insulation. 1 - electric receiver; 2, 3 - grounding; 4 - dzherelo electricity; 5 – rozpodіl U pr for the presence of grounding; 6 - those same for yoga manifestness; z chol - the last opir of the body of a person; R s, n - Opir re-grounding; R zm - Opіr earthing neutral of the generator; U pro - voltage drop on the zero rod; U pr - voltage drop due to the presence of re-grounding; U pr - those same for yoga manifestness.

The physical nature of the neutralization of the zeroing system is explained a little, for which an important zeroing scheme with one electric receiver is presented. Shown is the neutralization of the dzherel of electric power with the body of the electric receiver; a diagram has been drawn, which characterizes the change in the earth's voltage, which is to blame for poor insulation in two fluctuations:

– zero conductor may only be grounded by the dzherel of electric power;

– zero wire may re-grounding at the electrical receiver.

At the first moment, the voltage of the dot is increased at the bіk of the electric receiver and reaches the maximum value of the bіl of the th hull; Numerically, the voltage is greater than the voltage drop on the neutral wire in case of a short circuit, which is the cause of the electrical receiver between the phase and neutral wires. If the support of the phase wire r f will be more than the support of the zero wire r 0, then the voltage of the dot at the moment of a short flicker on the body of the electrical receiver with the presence of a repeated grounding will be more than half of the phase. Yakshcho well opir zero drot will be more support phase, then the voltage of the dot will be more than half of the phase. You can change the voltage of the dot with two ways: by increasing the cut of the zero dart, or by controlling the repeated grounding.

Visnovok: physical daylight for the auxiliary system of zeroing the field at the reduced voltage of the dotik with a way to change the support of the zero core and redistribute the voltage of the dotik between the main (transformer neutral) and the secondary (at the electrical receiver) grounding switches for the additional secondary grounding do not play a role in the numbers.

7. Zahisne viknennya.

Zahysne inclusion- the whole system is zahistu, based on the automatic switching on of the electrical receiver, as if on the metal parts of yoga, as it is not normal to be under a voltage, it is a voltage that is not safe for a person.

Such a system is recognized for merezhі z insulated neutral, Importantly, you can vikoristovuvat і for merezhi іz grounded neutral.

Robotic principle:

Schematic diagram zahisnogo inclusion.

1 - the body of the electric receiver; 2 - spring, which retracts; 3 - a blot, which removes the vimikacha knives; 4 - a cat, what does it include; 5, 6 - grounding.

When a person is hit by a voltage that is caused on the body of a single electrical receiver due to poor insulation, two types of losses are possible: the electrical receiver is not grounded and may be grounded.

The first way to see the little ones (I) is the contact from the grounding socket. On the deakіy vіdstanі vіd elektropryymachа, scho protect, clog into the ground grounding. Dali put himself vimikach chi zahisny vimikach. On a small scale, all the elements of the vimikach are based on the principle of diversification. Zahisniy vimikach(Vimikach) maє kotka, which opens the lancet when the voltage is applied to it. Vіn mozhe mother i kotushka, sho turn on, sho allow zdіysnyuvati zdіysnyuvaty nadushkannyam buttons. The cat, which you see, is wiping out the vimikach at the closed switched-on station for the help of the buckle. One end of the coil came to the body of the electric receiver, the other - to the wine earthing machine. At the same time, there is a need for insulation between the body of the electrical receiver and wine grounding phase voltage. The cat, which you see, leans under the strain, and through it the strum goes. Її the core will be drawn in and make the stretching brace. The spring retracts the knives of vimikacha, and the lancet breaks. The voltage of the dotik on the body of the electric receiver is no longer there, and you will become safe with it.

Like the body of the electrical earthing device, the earthing switch will be turned on. In case of poor insulation, there will be a voltage on the body of the electrical receiver, but it will no longer be equal to the phase one. The value of the voltage is to indicate the voltage drop on the grounding device, equal to the earth current, multiplied by the earthing device grounding support. In my case, the vimikacha cat may be loosened for a small amount of voltage. The basis of the defense for the help of a dependent power supply is the power supply of a power supply. Chim lesser hour dії vіdklyuchayugo pristroyu, tim nadіynіsha system zahistu. One of the main problems of the zahisnogo inclusion is those that can be spratsovuvaty and in case of complete shutdown, and even on the cob the development of a poshkodzhennya. Tse Yogo Sutteva Perevaga.

Laboratory robot

Follow-up of efficiency

grounding in electrical installations

voltage up to 1000 V

4.1. Meta ta zmist roboti

Follow the influx of zahisnogo grounding on the safety of strumming in electrical installations that live in three-phase three-wire lines from an insulated neutral and in three-phase five-wire lines from a grounded neutral with a voltage of up to 1 kV.

1. To increase the efficiency of the grounding of the electric damper housing, which is to live in a three-phase three-wire line from an insulated neutral.

2. Doslidit zalezhnist naprugi on the grounded building elektrospozhivachacha in the size of the support of the 1st grounding outbuilding in the measure from the insulated neutral.

3. Assess the unsafeness of the strum in case of one-hour flickering of the various phases of the line with the insulated neutral on the housings of the electric shock absorbers, which may be near the grounding outbuildings.

4. Follow up the influx of protective grounding on the unsafe strumming when the phase is short on the body of the electric shock, which will live in a three-phase five-wire line from the grounded neutral.

4.2. Theoretical part

4.2.1. Zagalni vіdomostі

Technological progress is accompanied by the improvement of energy consumption of people in all spheres of their life. At the same time, the nomenclature of vicoristing electrical installations is expanding, so that there may be some mutually connected electric power in the boundaries of this expanse or a place.

Under the power of electricity, it becomes clear whether it is the power of vibration, transmission, power distribution, for example: machines, transformers, devices, vimiruvalnі fittings, attachments, cable products, electrical receivers.

An electric stream, flowing through the human body and giving a thermal (thermal), electrical and biological inflow, may cause serious consequences for health. I want electrical injuries (injuries, viklikanі vplivom elektrichnogo struma or elektrichnі ї arcs) to become only an insignificant part of the total traumatism, the number of fatal electrical injuries in the total fatal traumatism is great.

Diya on the human body of an electric strum of the same and the same parameters to lie in the form of a superfluous sharpening and become the body itself: an electric strum, which does not exude a littered spit on the body of a person in one mind, can lead to a deadly result in others. Nebezpeka razhennya elektrichnym strum polyuєєєєєє th tim, scho vin can not but manifestations for the help of our organs chut.

The defender of people in the form of an electric shock for the minds of the mind and will be reached by a different method, one for the earth.

4.2.2. Appointment, validity, that sphere of zastosuvannya

It is not necessary to ground people for the protection of people in case of damage by an electric attacking strum with an indirect bunker with conductive parts of the electrical installation and third-party conductive parts, but not parts of the electrical installation (for example, metal structures, metal gas pipelines, pipes, water pipes). , underpinnings and walls from non-insulating material), as they can be supported under the pressure at the same time.

Under the hostile strum, there is a strum that can pass through the body of a person, the characteristics of which can be pathophysiological or cause injury.

Under the wired part, the non-current-carrying part is understandable, the human dot is accessible, as it can be under tension when the insulation of the strum-like parts is damaged.

Zakhisnu is grounded by the Electric Izdnannya, Earth, Ekvayvalent, Netstood, Non -Izolov, Land with water (Nadali - Earth), Vidkritikh of the Provide Parts of Elektrovka, not by the Parts of the Years under the pressure at the time of the shock.

For electrical installations with a voltage of up to 1 kV, it is fallow according to the type of streak-conducting conductor systems (for a replacement strum - single-phase two-three-wire, two-phase three- and five-wire and three-phase chotyrokh and five-wire for a permanent stream - two-three-wire according to GOST R) 50571.2-94 accepted grounding systems: TN, TT, IT.

Letters of meaning here may have such a sensation.

First letter in known ( I or T) determines the nature of the grounding of the lifeline (generator, transformer) (Fig. 4.1)

Litera I(Insulated neutral) means that all the strum-conducting parts of the living room are insulated from the ground, or one point is grounded through an attachment or an attachment, which is a great opir.

Litera T(TERRA, earth) means that the strum-conducting part (sound neutral) of the living room is connected without intermediary from the grounding attachment (the neutral is deafly grounded).

Another letter indicates the nature of the grounding of the critical conductive parts of the electrical installation.

Litera T means that the conductive parts of the electrical installation are grounded independently of the nature of the connection between the earth and the earth.

Litera N(neutral) indicates a non-intermediate connection between the critical conductive parts of the electrical installation and the neutral of a dead-earthed housing.

System TN- a system in which the neutral of the living wire is deafly grounded, and the conductive parts of the electrical installation are connected to the neutral of the dead-earthed wire for the help of zero dead or sleeping conductors.

According to the method of laying a heating conductor, the TN system is subdivided into:

system TN– C, the same function of the zero protection and zero working conductor is used in one PEN-conductor on the whole line (Fig. 4.1a);

system TN– S at the same zero-point (PE) and zero working (N) conductors are separated on the whole stretch (Fig. 4.1 b);

system TN– C– S, in the function of a zero worker (N) and a zero worker (PE) conductor in one (PEN) conductor in the same part, starting from the zherel of life (Fig. 4.1);

Substation Electrical installation budіvlі

Substation

Rice. 4.1. Types of grounding systems:

a – TN-C system; b – TN-S system; c – TN-C-S system; d – TT system;

e - IT system.

Yak dodatkovy zahіd at the system TN There may be jamming (and in some cases, the shoes are viscous) a repeated grounding circuit on the input of the guard, which will connect with the null conductor of the dzherel of life.

System TT- the system, in which the neutral of the dzherel is deafly grounded, and the conductive parts of the electrical installation are grounded behind an additional grounding outbuilding, electrically independent of the dead-grounded neutral of the dzherel (Fig. 4.1 d).

System IT- a system in which the neutral of the living room is isolated from the ground or grounded through an attachment or an attachment, which is a great support, and the conductive parts of the electrical installations are grounded (Fig. 4.1 e).

Electrical installations with a voltage of up to 1 kV of residential, communal and commercial life and state-of-the-art installations are, as a rule, responsible for estimating live power from a dead-earthed neutral from the TN system.

The TT type grounding system is used in electrical installations with a voltage of up to 1 kV only in quiet weather, if electrical safety cannot be secured with a TN type grounding system to safe values).

Electrical installations with a voltage of up to 1 kV from an insulated neutral are, as a rule, the mother of an IT-type grounding system, if it is unacceptable, interrupt the life at the first flicker to the ground or on the conductive parts.

Z'dnannya vodkritih conductive parts from the ground zdiisnyuєtsya for the help of the grounding outbuilding, which is the supply of the grounding and grounding conductors.

Under grounding, a conductor (electrode) is understood, or a combination of electrically connected conductors, which are in contact with the earth without a middle, or through an intermediate conductor, for example, through an uninsulated water body.

Under the grounding conductor, there is a suitable conductor, which is the bottom part of the electrical installation, which is grounded, from the grounding one.

Vіdpovіdno to the Rules for the construction of electrical installations (PUE), grounding devices are subdivided on natural and piece.

As natural grounding workers can be vikoristan:

metal pipes for water pipes, laying near the ground;

casing pipes of the Sverdlovin;

metal and cast-iron structures that will be built up and spores, which are rebuyed from the ground;

metal sheaths (aluminum cladding), armored cables, laid near the ground. Sheaths of cables can be single grounding devices for the number of cables in less than two;

lath ways of the main non-electrified bays and subway ways for the presence of a navmisny I will build a jumper between the laths;

other things that are in the earth metal structures that argue.

Piece earthing machines can be made of black or galvanized steel or midi with a cross section: round, straight-cut, ducted, trumpet and bagatodrotyanim mid-rope. Vіdpovіdno to PUE fallow, depending on the type of material and the profile of the cut, the diameters, the area of the transverse cut and the thickness of the walls (at pipes) of the grounding are installed.

Quantity, geometrical sizing and method of roztashuvannya zaglyuvachivnі zabezpechuvat at the same support of the soil, the size of the support of the zakhisnogo grounding is necessary.

Vіdpovіdno to GOST R 50571.3-94 and PUE zakhisne zahіdno vykonuvatі vіkonuvatіv vіdnіvіh vіdnyh vypadki.

At a rated voltage greater than 50 V in a variable struma and greater than 120 V in a permanent (vacuum-rectified) struma - in all electrical installations;

At a rated voltage of 25 V in a replacement struma and more than 60 V in a permanent (rectified) struma - only in areas with a moving unsafe, especially unsafe and ovnishnіh electrical installations;

At a nominal voltage of up to 25 V of a permanent stream and up to 60 V of a permanent stream - only in vibration-prone areas and electrical installations.

Application from promoted by unsafe are characterized by the presence of one of the five advancing minds, which create an increase in the security of the electric shock:

water content, if water content is visible again, 75%; such apparitions are called sirimi;

the temperature is high, if the temperature rises again and again with a surge of different thermal vibrations, it is constant or periodically (more than 1 doby) exceeds +35 0 С; such applications are called speculators;

streum-conducting saws, if behind the minds of virobnitstva one sees technological saws, which can settle on the streum-conducting parts, penetrate into the middle of machines and devices too thin; such applications are called smoking;

strumoprovidna pіdloga (metal, earthen, concrete, concrete, thin);

the possibility of a one-hour dotik of a person to a metal structure budіvel, which can be lifted from the earth, technological devices, mehanіzmami just. from one side, and to the metal buildings of the electric power supply (in the middle of the conductive parts), from the other.

The premises are especially unsafe and are characterized by the presence of one of the advancing three minds, which create especially unsafe electric shock:

especially moisture, if the water content is again close to 100% (stele, wall, pillow and objects that are in the surroundings, covered with water);

chemically more active or organic middle ground, if aggressive vapors, gasses, radiants are calmed down for a long time, settle down in the deposit or color, which destroys the insulation and stream-conducting parts of the electric power;

one hour the appearance of two or more minds of the promoted insecurity.

The territory where electrical installations are exposed to the danger of injuring people with an electric jet is equated to a particularly unsafe place.

Other occupants can be taken to accommodating without any further insecurity.

Zahisny grounding is provided with cases of electrical machines, transformers, lamps; bring electric devices; frameworks rose shields, control panels, shields, closet thinly; metal structures of separate outbuildings, cable structures, cable couplings, sleeves and pipes of electrical wiring, trays, boxes, metal structures, on which electrical control is installed; metal shells and control armor power cables; metal cases and transferable and portable electrical appliances; electric power, installed on ruhomy parts, workbenches, machines and mehanizmіv just.

It's easy to send your harn to the robot to the basics. Vikoristovy form, raztastovanu below

Students, graduate students, young adults, like victorious base of knowledge in their trained robots, will be your best friend.

Placed on http://www.allbest.ru/

Ministry of Education and Science of the Russian Federation

federal state installation lighting higher professional education "Bilgorod State Technological University named after. V.G. Shukhov"

Three disciplines: BJD

Theme: "Zahistno grounding"

Wickonaw: student

PSZ group - 51

Agranov Kirilo

Accepted by: Nosatova E.A.

Bilgorod 2014

Zakhisne grounding (zeroing) is the main approach to the protection of metal structures. The main meta approach is to protect against a possible blow with a strum of a coristuvach, when it flickers on the body in that case, for example, an electric strum strikes at the time of a phase dart flickering, if the insulation is damaged. In other words, grounding is a stand-in for the protection functions. There is no need to ground all electrical equipment that is in the booth: most of them may have an overhead plastic case, which by itself protects the enemy with an electric jet. It is not necessary to ground the ground because of the fact that the bodies of machines and devices are not connected to the "earth", but from the grounded zero drotom, which goes to the transformer substation along the choti-ri-wire power transmission lines. For the safety of the new safety of the people, the earthing opir (at once from the circuit) is not guilty of changing 4 ohms. For the purposes of the method of transfer to the river (collection and collection), a control check is carried out by a special laboratory.

Grounding - the price of navmisne electrical installation, whether it is a point of an electrical fence, electrical installations or a possession, from a grounding outbuilding.

The grounded heaps are stored by the lands (the proceedings of the sub -pepper of the sennes of the proceedings, it is found in the electric contact with the land of the unzipersedno aboa through the industrial of the middle official) I providnik, the Z'ydnnuulyuna (the point). The grounding device can be simple with a metal shear (mostly steel, usually medium) or with a foldable complex of elements in a special form. The amount of grounding depends on the value of the support of the grounding outbuilding, which can be lowered, increasing the area of the grounding, or the conductor of the middle - the vicorist, the impersonal shear, moving the salts near the earth thinly. Electric Opir grounding outbuilding is designated as a PUE

Before the technical methods and the benefits of protection, one can see: isolation of the streak-conducting parts with an annex of uninterrupted control; fence; electric hem; stagnation of a small voltage; electrical protection (blocking); signalization and security signs; zahisne grounding; nulling; shut down; zahist vіd nebezpeki pіd hour to the transition of the voltage from the upper side to the lower; compensation of strums zamikannya on the sinful earth. grounding grounding metal construction insulation

Zanulennya - navmisne electric z'ednannya with a zero drotom of metal non-current-carrying parts, as they can be supported by a voltage. The physical reality of the zero is for the one who zavdyaks are navmisno vykonan with the help of zero good guide metal connection of the body in the possession of a dead-earthed neutral dzherel livelihood, whether it is a flicker on the body, is transformed on a single-phase short chirp coming automatic dismissal emergency plot vіd merezhі apparatami zakhistu (zapobіzhniki, automatic vimics and in.).

Shut-off switch systems - all special electrical appliances, designated for switching on electrical installations in case of breakdown on the hull. If the main reason for the interference of the jet-conducting parts on the body is the possession and damage to the insulation, then the systems of the shut-off connection will have a permanent control over the insulation support, or the jets of the coil between the jet-conducting and non-streum parts of the structure.

One of the approaches for the provision of electrical safety for an hour of work on electrically controlled and grounded grounding.

Zahisnym grounding is called navmisne elektrichne z'єdnannya іz the earth or z її equivalent of metal invisible parts, yakі can opinitisya under the pressure. The defender is reachable by the path of changing the voltage of the dotik for the fluctuations of the potential when the stream flows from the electrical installation to the ground when the phase is broken on the installation body. The jet is rozt_kaєtsya vіd zemlyuvacha evenly on all sides on the surface and in the depths of the earth. At the world, in the distance, the grounding space of the strum is changing, to that which will increase across the globe of the earth, through which the strum will pass. It was established by Rozrakhunkovy way that the potential of the surface soil changes with distance from the grounding according to the law of hyperbole: from the maximum value (on the grounding) to zero at a distance of approximately 20 m.

At the zone of expansion of the strum, a person can be used with a difference of potentials, for example, on a large scale. The tension between two points of the lancet of the struma, which is one in the same on the same rock, on which a person stands at one hour, is called a tense crock.

The value of the voltage of the rock to fall on the width of the crop and the distance of the people from the place of the earth. In the world, in the distance, in the mist of the world, the voltage is changing. The voltage depends on the shape of the potential curve.

Grounding is structurally an attachment that is made up of grounding conductors and grounding conductors. Grounding devices can be natural and piece. Like natural grounding, vicorous metal elements are laid, laid in the ground, for example: metal elements (reinforcement) of concrete structures and spores, water supply and other metal pipelines (crym of combustible gases, rivers, as well as pipelines, covered with insulation), metal insulation. . If natural grounding devices are daily or their opir is not enough, piece grounding devices should be used.

Fallow in the field of roztashuvannya zemlyuvachіv schodo zagryuvannye ob'ektіv piece zemlyulyuvannya pod_lyayutsya on contour and vineyards. Sound the grounding electrodes, grounded vertically or horizontally into the ground. Most often, group grounding extensions are installed, which are made up of vertical shears, connected between themselves by a female or round steel. In order to improve the effect of vibrating the potential, the contour grounding is vibudovuetsya at the sight of the grid that is grounded.

Piece grounding devices are made from steel of a different profile. To ensure mechanical, thermal and corrosion resistance, it is recommended to take the following dimensions: diameter - 40 ... 80 mm, length - 2 ... 3 m.

Grounding conductors sounding are made from steel of straight-cut and round cross-section. At fencing with a voltage of up to 1000, the conductivity of the grounding conductors is less than 1/3 of the conductivity of the phase conductors. When laying a grounding bus in the middle of the bus, the smallest cut of a straight-cut bus may become 24 mm 2 for a round bus, the smallest diameter is 5 mm.

Vymogi to the power of the zahisnoy grounding and zeroing of the electric power are assigned to the PUE, it is obvious to such a stench it is the fault of the power rated voltage 380 and more than a vicious struma, and also 440 and more than a fast struma. Works in the premises with increased insecurity and especially insecure duties are installed in installations with an elastic life of more than 42 In a change and more than 119 In a permanent stream. Zahisnomu grounding and zeroing are supported by the metal parts of electrical installations, accessible to the dotik of people, as they can be supported under the voltage U In what vipadka strum, scho to pass through the people,

I 1 \u003d U cf / (R 4 + R ЗІЗ), (8.2)

de R 4 - Opir body of a person; R ЗІЗ opir koshtiv individual zakhistu, For їх vacancies R ЗІЗ = 0.

Zahisne grounding zastosovuєtsya to secure the zakhistu of people in the presence of an electric streak at the dot to metal non-strium parts of the object, so that they can oppose under the pressure of the shock of the insulation. It is not necessary to ground the ground with a path of a navmisny z'ednanny (metal conductors) of non-current-carrying parts of electrical installations from the "ground" (Fig. 8.1) or with a її equivalent (GOST 12.1.030-81).

The principle of dії zahisnogo grounding - reduction to safe values of the voltage of the dot and the crock of the voltage, which is blamed when the phase is shorted to the case. It is within reach of the change in the potential of the possession, which is grounded, \u003d I 3 R 3 (due to the small support of the grounding outbuilding - 4 ... 10 Ohm), as well as the change in the potentials of the grounded possession.

Grounding workers can be natural and piece. Metallic and reinforced concrete constructions will be built before us, as if they were guilty of making it uninterrupted. electric lanceug from metal. Natural grounding can be laid in the ground water supply and other metal pipelines,

switching off pipelines of combustible and vibukhovy gases and sumishes; metal zalezobetonnі konstruktsії budіvel ta sporud, scho to be found in the middle of the ground; lead sheaths of cables laid near the ground, thin. For piece earthing machines sound the vertical and horizontal electrodes.

Rice. 1. Scheme of zahisnogo grounding: a - important; b - equivalent

Like vertical electrodes vicorate steel pipes with a wall thickness of not less than 3.5 mm (sound pipe with a diameter of 50 ... 60 mm) such a steel edge with a wall thickness of not less than 4 mm (sound with a wall thickness of steel with a diameter of 40x40 to 60x60 mm) and a length of 2.5 ... 3.0 m. Widely zastosovuєtsya also bar steel with a diameter of not less than 10 mm, a length of up to 10 m, and sometimes more. As a horizontal electrode for the connection of vertical electrodes, strip steel with a cross section of not less than 4x12 mm and steel of a round cut with a diameter of not less than 6 mm are installed.

Separate contour and wine grounding extensions. At contour grounding single grounding devices are installed evenly along the perimeter of the Maidan, where the installation is placed, for grounding. In the middle of the circuit, which is protected, it reaches the potential of the earth, which indicates the minimum value of the voltage of the dot and the crock of the voltage.

The wine-grounding annex is placed in a pose of a Maidan, the possession is de-roofed, which is grounded, to which the potential of the earth and the buildings of the grounded possession reach the lesser world. It is not good for grounding to stop at small values of the struma to ground in installations with a voltage of up to 1000 V, the potential of the grounding device is not higher than the voltage that is allowed, dotik.

1. Grunt - div. for the variant, the view of the soil in the table. 1 with pet support, Ohm m

Table 1

2. how to ground steel pipes d = 0.08 m and length l = 2.0 m (from the 1st to the 10th option), length l = 2.5 m - іnshі, roztashovanny vertically and z'єdnі on zvaryuvannі steel swarm 40 * 4 mm;

3. the transformer pressure is up to 90 kVA, which is necessary for the norms of permissible support for the grounding facility [r h]< 10 Ом.

4. An electric motor with concrete mixing expansion in another climatic zone 1-10 options for normal, reshta - increased moisture.

Minimum amount of smuga, which is used for single grounding L = 2 l (n-1) a de a = 2 l

The opir of a single vertical grounding device R B, Ohm is determined by the formula:

de t - distance from the middle of the earthing machine to the surface of the ground, m;

l,d - depth and diameter of shear grounder, m.

z rozrachunkom = ssh,

de sh - seasonality coefficient, which is a good opportunity to promote the support of the soil by stretching the rock; h - nursery opir soil.

Rosrakhunkovy pytomy opir ґruntu vyznaєmo for the formula:

with rozrahunkom = 50 ohm * 1.5 = 75 ohm.

Known required quantity vertical grounders:

de - admissible for the norms of the opir of the grounding device; - Coefficient of variation of vertical grounding devices.

The minimum amount of smuga that can be obtained by single grounding

L= 2 l (n-1) a ,

L = 2 * 2 (4-2) * 4 = 32m,

Calculate the basis of the steel smuga Om, which is the grounding shearer:

de l - Dovzhina smuga, m; t - distance from smuga to the surface of the earth, m;

d=0.5b(b - line width).

Significantly, the rozrahunkovy pytomy opir ґruntu in case of successful smog at the sight of a horizontal electrode:

Calculation of the deep rozrakhankovy opir of the grounding outbuilding R with the improvement of a happy smog:

Is it correct to cover the grounding of the attachment to the responsibility of the minds of R? .

As a rule, it is necessary to increase the number of vertical ground electrodes (electrodes).

Placed on Allbest.ru

Zahisne grounding appointment. Zahisne grounding

4.2. Theoretical part

4.2.1. Zagalni vіdomostі

4.2.2. Appointment, validity, that sphere of zastosuvannya

It's easy to send your harn to the robot to the basics. Vikoristovy form, raztastovanu below

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