RU220559U1 - GROUNDING CONNECTOR - Google Patents

Abstract

The utility model relates to the field of electrical engineering and can be used as a grounding conductor for grounding electrical installations, as well as lightning protection. A grounding conductor consisting of individual steel rods with chamfers at the ends, with a protective metal coating, selected taking into account the admissibility of their contact with the metal coating of the rods, with two axial holes tapering inward; between the two axial holes of the coupling there is a through hole that provides direct end contact of the connected rods when they are immersed in the ground, an annular protrusion is located inside the coupling, which ensures fixation of the relative position of the rods relative to the coupling, and the dimensions of the chamfers at the ends of the rods are selected in such a way as to guarantee direct end contact of the rods. The technical result is a simplification of the process of immersing the ground electrode into the ground. 2 ill.

Description

The utility model relates to the field of electrical engineering and can be used as a vertical grounding conductor for grounding electrical installations, as well as lightning protection.

The ground electrode is a set of vertical conductive elements (rods) interconnected along their length and in electrical contact with the ground.

The main criterion for the performance of grounding is the minimum resistance to the flow of electric current through the ground electrode into the ground during the entire period of its operation, which is ensured by:

the possibility of deepening the ground electrode into the ground to the calculated depth;

reliable electrical contact between its individual elements;

corrosion resistance of both individual grounding elements and their contact connections.

The most effective are deep vertical grounding rods (rods connected sequentially along their length by means of couplings with immersion to a depth of up to 20 m, depending on the specified value of the grounding resistance and the properties of the surrounding soils), allowing to achieve minimal resistance to the spread of electric current at the lowest cost and cost. limited area due to the use of denser and wetter layers of soil with better electrical conductivity, located at great depths.

The immersion of a vertical deep ground electrode is carried out using a vibratory impact tool (jackhammer) with a single impact energy in the range from 25 to 60 J by transferring the impact load from the striker through the overlying rods to the rods located below, up to the first of the immersed rods, overcoming the drag of the soil .

The process of immersion of a vertical ground electrode is described by the theory of penetration of solid bodies into soil environments during single and multiple impacts [1, 2], based on the following hypothesis: as a result of impacts, micro- and macrocracks appear on the soil surface, leading to loss of its strength and, as a consequence, , to reduce the drag force for the penetrating body. During the interaction of several colliding elastoplastic bodies (in this case, rods) forming an impact system, the energy of the initial impact decreases (dissipates) with distance from the place of its application to the first of the immersed rods, partially spent on local plastic deformations in their contact zones [3] . The more such contacts, the correspondingly greater the loss of energy from the initial impact. The appearance of an additional intermediary body between the individual immersed rods (for example, an insert, a partition or a gasket) will lead to additional dissipation of the energy of the initial impact into local deformation in this intermediary body, and to achieve immersion to the same depth, a large impact load will be required. Since the depth of immersion of the ground electrode into the ground can reach 20 m, the number of contact connections of individual elements (for example, rods 1.5 m long) can reach up to 12. In this case, the loss of impact energy turns out to be so significant that it is often difficult to immerse the rods to the calculated depth using available tools and requires more powerful, and therefore more expensive, equipment.

Therefore, in the case of immersion of grounding elements, the optimal method is considered when the shock load is transmitted through direct end contact of the overlying rod with the rod located below, without any additional intermediary bodies.

There is a known technical solution No. RU 176327 U1, where direct end contact of two rods is carried out by means of a coupling when they are immersed in the ground. However, in this case, the connection of the rods is made using a threaded coupling, and threads are cut at the ends of the rods, which complicates and increases the cost of ground electrodes during their production.

As for the electrical contact between the individual elements of the ground electrode. Such contact is most easily achieved by crimping [4]. In the case of immersion of grounding rods into the ground, under the influence of an axial shock load, the rods are compressed, entering the holes of the coupling, tapering inwards (conical). The essence of crimping in this case comes down to the deformation of the softest of the materials or the joint deformation of the materials of the “rod/coupling” pair with the formation of a contact zone between them.

Regarding corrosion resistance, the following should be noted. To ensure the durability of the grounding device, the materials and design of the grounding devices must be resistant to corrosion [5]. To prevent corrosion of grounding elements in the ground, during their production, either corrosion-resistant materials are used, for example, copper, brass, bronze, stainless (chromium-nickel) steel, or electrically conductive protective coatings covering carbon and low-alloy steel that are susceptible to corrosion. Due to the high price of grounding conductors made of stainless materials, which are 3 to 4 times higher than the price of coated steel grounding conductors, preference is often given to the latter.

The most commonly used is a copper electrically conductive coating formed by a galvanic method on a steel product or a zinc electrically conductive anti-corrosion coating applied to a steel product by cold, galvanic, hot or thermal diffusion galvanizing. The protective electrically conductive coatings listed above are combined into the concept of “metal coatings”.

Since, by definition, a ground electrode is a set of conductive parts connected to each other, the requirement of corrosion resistance fully applies to their connections as well. In order to avoid the so-called contact corrosion, which reduces the conductivity of the connection (since the corrosion products of metals in the connection are less than the conductivity of the original metals), corrosion resistance is determined by the selection of appropriate types of metals of the rod and coupling in contact with each other, selected from the group including brass, bronze, carbon and low alloy steel with zinc or copper coating, stainless steel. The admissibility of contacts of different metals is established taking into account the difference in their own potentials [6]. For example, zinc alloys and coatings are also acceptable for contact with zinc alloy and coating. On the contrary, for example, brass is not acceptable for contact with zinc alloys and coatings.

From the description of utility model No. PL 65243 Y1, a grounding kit is known, consisting of rods coated with a layer of hot zinc and a brass coupling (see the original and translation of the description into Russian in Appendices 1 and 2).

The grounding kit consists of hot-dip galvanized rods, as well as a brass threadless coupling with two cylindrical axial blind holes with serrated side surfaces. Between the two cylindrical axial blind holes there is a partition into which the ends of the connected rods rest. According to the authors of the technical solution, reliable mechanical and electrical connection of the grounding elements is ensured by the collapse of the softer zinc coating layer of the rods, into which, when exposed to an axial shock load during their immersion, the teeth located on the side surface of the blind holes of the coupling are pierced.

One of the significant disadvantages of this technical solution is that when connecting individual rods using a coupling, there is direct contact between the galvanized surface of the rod and brass, which is unacceptable [6], since it leads to corrosion of the contact connection. In addition, there is also the possibility of damage to the zinc coating layer when it is exposed to sharp coupling teeth under the influence of a vibration-impact load, exposing the steel base, which can also lead to corrosion.

In terms of technical essence, the technical solution closest to the proposed utility model is the technical solution of the American company ERICO, which supplies grounding components under the ERITECH® brand (ERITECH Grounding & Bonding Catalog, pages 14 and 17, see the original at: http://www. ecoptions.com.au/uploads/ERITECH%20Groundinq%208i.%20Boninq%20Catalogue.pdf

see the originals on pages 14 and 17 in appendices 3 and 4, translations into Russian on pages 14 and 17 in appendices 5 and 6).

The grounding kit consists of rods and a threadless coupling with two axial blind conical holes. When exposed to shock loads when immersed in the ground, the rods entering the coupling are compressed, forming a permanent electrically conductive connection. This coupling is called a compression coupling. Between the two axial blind holes there is a partition against which the ends of the connected rods rest, and the rods themselves have points (chamfers) at the ends to compensate for plastic deformation (riveting) of the ends of the rods when exposed to impact loads. Copper-plated or galvanized steel rods, or stainless steel rods can be used as grounding rods. At the same time, in order to avoid contact corrosion, the materials of a specific contacting “rod-coupling” pair are selected taking into account the permissibility of contact of their materials. So, when using a copper-plated grounding rod, a brass coupling is used in the contact pair. When using galvanized rods, a galvanized steel coupling is used.

The disadvantages of the known technical solutions described above for connecting rods using threadless (compression) couplings is the presence of a partition in them that prevents direct contact of the rods when transmitting shock loads during their immersion into the ground, which, as discussed above, is an additional intermediary element that reduces the energy of the initial impact required to immerse the ground electrode to the calculated depth. That is, the energy of the initial impact is additionally spent on local plastic deformation in this intermediary element, which requires the use of more powerful and more expensive equipment.

The proposed utility model is designed to eliminate the shortcomings of known technical solutions and ensure the achievement of a technical result in the form of simplifying the process of immersing the ground electrode into the ground.

The proposed utility model includes a grounding device consisting of individual steel rods with a protective metal coating, a connecting coupling made of metal selected taking into account the admissibility of their contact with the metal coating of the rods, with two axial holes tapering inward, between which there is a through hole providing direct end contact of the connected rods.

The essence of the utility model is illustrated by drawings, where

in fig. 1 shows a general view of the contact connection of two rods by means of a coupling, combined with a local frontal section;

in fig. Figure 2 shows a frontal section of the coupling.

The ground electrode consists of separate steel rods 1 and 2 with a protective metal coating and a connecting coupling 3 with two axial holes 4, tapering inward; between the two axial holes of the coupling there is a through hole 5, providing direct end contact of the connected rods 6, while inside the coupling there is an annular protrusion 7, which ensures fixation of the relative position of the rods relative to the coupling, and the dimensions of the chamfers 8 at the ends of the rods are selected in such a way as to guarantee their direct end contact.

When the ground electrode is immersed in the ground, the connecting coupling 3 is pushed onto the upper end of the first of the immersed rods 2 by impact with a force sufficient to compress the rod in the coupling until it rests with the side surface of the chamfer on the annular protrusion 7 inside the coupling. The next grounding rod 1 is inserted into a free hole on the opposite side of the coupling and, during the immersion process, is driven in by an axial impact with a force sufficient to compress the rod in the coupling until it stops at the end of the previous rod 2. The rods entering the coupling during the impact load form a one-piece electrically conductive connection. In this case, the coupling is fixed from axial displacement relative to the underlying rod 2 by an annular protrusion 7.

From the stated essence of the proposed utility model, it obviously follows that eliminating the brass partition and ensuring direct end contact of the steel grounding rods when transferring the impact load from the overlying rod to the rod located below without any intermediary elements during the immersion process reduces the loss of the initial impact energy, simplifying the immersion of the ground electrode into the ground.

The quantitative effect of using the proposed utility model, which consists in eliminating the brass partition and ensuring direct end contact of the connected steel rods, can be assessed by comparing the values of the elastic moduli of brass and steel. As is known, the modulus of elasticity of a material characterizes its resistance to compression during elastic deformation, or its ability to deform along the axis when exposed to a longitudinal force. The lower the elastic modulus in the compared options, the more the material is deformed under the influence of the applied force, which means that most of this force is spent on deformation (crushing). And, on the contrary, the greater the elastic modulus of the material, the less it deforms, i.e. is more elastic and therefore, when transmitting an impact load, most of it is transmitted in the form of an elastic impulse and less is spent on its deformation.

In the proposed utility model, the brass partition is eliminated and direct end contact of the connected steel rods is ensured.

From publicly available sources [7, 8], it is known:

modulus of elasticity of steel E _st =200000 MPa,

modulus of elasticity of brass E _lat = 116000 MPa, i.e. the difference between these values is about 40%.

Bibliographic data

1. Koronatov V.A. Elementary theory of penetration of a striker into solid soil media during a single impact, taking into account emerging cracks // Systems Methods Technologies. 2021. No. 1 (49). pp. 25-33.

2. Koronatov V.A. Modeling of pile immersion and the process of soil compaction during multiple impacts // Systems Methods Technologies. 2021. No. 1 (49). pp. 34-40.

3. Manzhosov V.K. Models of longitudinal impact / V.K. Manzhosov. - Ulyanovsk: UlSTU, 2006. - 160 p. ISBN 5-89146-811-5.

4. GOST 10434-82. Electrical contact connections. Classification. General technical requirements.

5. GOST P 50571.5.54-2013 Low-voltage electrical installations. Selection and installation of electrical equipment. Grounding devices, protective conductors and potential equalization conductors.

6. GOST 9.005-72. Unified system of protection against corrosion and aging. Metals, alloys, metallic and non-metallic inorganic coatings. Acceptable and unacceptable contacts with metals and non-metals.

7. Brand of steels and alloys. 2nd ed., corrected. And additional / Zubchenko A.S., Koloskov M.M., Kashirsky Yu.V. and others. Ed. A.S. Zubchenko. M.: Mechanical Engineering, 2003. 784 p.

8. Mechanical engineering. Encyclopedia. T. II-3. Non-ferrous metals and alloys. Composite metal materials. / Under the general editorship of I.N. Friedlander. M.: Mechanical Engineering, 2001. 880 p.

Claims (1)

A grounding conductor consisting of individual steel rods with chamfers at the ends, with a protective metal coating, a connecting coupling made of metal selected taking into account the admissibility of their contact with the metal coating of the rods, with two axial holes tapering inward, characterized in that between the two axial The coupling holes have a through hole that ensures direct end contact of the connected rods when they are immersed in the ground; inside the coupling there is an annular protrusion that ensures fixation of the relative position of the rods relative to the coupling, and the dimensions of the chamfers at the ends of the rods are selected in such a way as to guarantee direct end contact of the rods.