JPH01663A - Grounding materials and structures - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Field of industrial application B1 Overview of the invention C0 Prior art 1 Problems to be solved by the invention B1 Means for solving the problems F0 Effect G. Examples (G-1) Examples of grounding materials (G-2) Example of grounding structure H0 Confectionery A of the invention, industrial application field The present invention relates to a grounding material used for embedding a grounding electrode, and a grounding structure using the above-mentioned grounding material.

B0 Overview of the Invention The first invention realizes a grounding material that is harmless to humans and animals and has a low electrical resistivity by mainly using a burned product of sludge obtained through water treatment.

The second invention has a strong grounding effect (economical This realizes a grounding structure.

The third invention is a grounding material that has a large grounding effect and is economical by dissolving it in water and injecting it around the buried ground electrode to form a ground layer. This realizes a grounding structure.

C6 Conventional technology Conventionally, in various electrical equipment such as power equipment and communication equipment, electrical connection between the electrical equipment and the earth has been used. So-called grounding is used to protect the human body and the above-mentioned electrical equipment from ground faults, etc., and to improve communication clarity.

In electrical equipment where such grounding is performed, that is, grounding equipment, a grounding electrode made of a metal rod, metal plate, bare wire, etc. connected to the electrical equipment is generally buried in the ground to reduce the resistance between the grounding equipment and the earth. (so-called ground resistance) is kept sufficiently low. However, the electrical resistivity of the ground varies as shown in Table 1, and in particular, in high resistivity areas such as mountains, riverbanks, and riverbed ruins, the electrical conductivity of the soil near the grounding electrode must be improved to ground the ground. So-called ground resistance reducers are used to reduce resistance.

Table 1 Electrical resistivity of the earth [Ω-m] In the past, electrolytes such as table salt and charcoal were used as the earth resistance reducing agent, but in recent years, chemically treated conductive resins and mixtures of carbon and quicklime have been used. Proposals have been made that mainly focus on

The grounding structure using the above-mentioned grounding resistance reducing agent is, for example, as shown in FIG. After that, the groove 93 is backfilled with residual soil 94 to form a pseudo-ground body 95 with low electrical resistivity around the ground electrode 92 due to the ground resistance reducing agent, increasing the apparent size of the ground electrode 92. This increases the grounding effect.

D0 Problems to be solved by the invention By the way, the drawbacks of the above-mentioned grounding resistance reducing agent are that the charcoal corrodes the copper grounding electrode, and the electrolyte gradually diffuses into water, so the effect of reducing grounding resistance does not last. However, chemically treated conductive resins have the disadvantage of being difficult to use in fields or near water veins due to concerns about chemical damage to humans, livestock, and crops.

In addition, in the grounding structure using the above-mentioned grounding resistance reducing agent, since the grounding resistance reducing agent mainly made of the above-mentioned chemically treated conductive resin or a mixture of carbon and quicklime is expensive,
Since only a small amount of the grounding resistance reducing agent is used, it may not be possible to obtain a sufficiently low grounding resistance, or the grounding resistance reducing agent may be washed away by rainwater or underground water, losing its effect in reducing grounding resistance, and causing a ground fault in the worst case. There was a risk that it would lead to an accident.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention provides a grounding material that is harmless to humans and animals and has a low electrical resistivity, and also provides an economical grounding structure that uses the above-mentioned grounding material and has a high grounding effect. It is something.

Means for Solving E0 Problems In order to solve the above-mentioned problems, the grounding material according to the first invention is characterized in that it is mainly composed of a calcined product of sludge obtained through water treatment. In order to solve the above-mentioned problems, the grounding structure according to the second invention uses a grounding material mainly composed of burnt sludge obtained through water treatment, and a grounding electrode is added to the soil layer on the site of the grounding equipment. It is characterized by being buried.

In order to solve the above-mentioned problems, the grounding structure according to the third invention uses a grounding material mainly composed of burned sludge obtained through water treatment, which is dissolved in water and injected around the buried grounding electrode. It is characterized by forming a ground layer.

F6 effect The grounding material according to the first invention exhibits low electrical resistivity when it contains water. Furthermore, the burned sludge, which is the main component of the grounding material, is harmless to humans and animals because pollutants are removed by incineration.

In the grounding structure according to the second aspect of the invention, a layer of soil in which the grounding material is made of soil and a grounding electrode is buried therein acts as a pseudo-grounding body.

In the grounding structure according to the third aspect of the invention, a grounding layer formed by dissolving the above-mentioned grounding material in water and injecting it around the buried grounding electrode acts as a pseudo-grounding body.

G. Examples The present invention will be explained below using specific examples, but it goes without saying that the present invention is not limited to these examples.

(G-1) Example of grounding material Sample 1 of the grounding material according to the first invention was a burned product of sludge obtained by sludge treatment in a water purification plant, which will be described later.

When the electrical resistivity characteristics of Sample 1 were measured when it contained water, the results shown in FIG. 1(A) were obtained.

Sample 1 has a moisture content of 20% (dry state) to 50% (normal) when buried in the ground.
As is clear from the results shown in ), the electrical resistivity in this case is 100 [Ω-m] or less, and in particular, about 10 (Ω-m) in a normal state. The electrical resistivity of Sample 1 is very low compared to the electrical resistivity of high resistivity areas such as mountains, riverbanks, and riverbed ruins shown in Table 1.

In addition, when sample 1 is buried in the ground, it has water retention properties and not only maintains the water content at a normal level for a long period of time, but even if the electrical resistivity increases due to drying, the electrical resistivity decreases again due to water absorption. It was confirmed that

Furthermore, in the sample 1, as a result of a pollutant detection test, alkyl mercury, total mercury, cadmium, lead, organic phosphorus, hexavalent chromium, arsenic, and cyanide were found.

No pollutants such as PCBs or organic chlorine compounds are detected.
It has been confirmed that there is no risk of pollution even if it is buried underground.

In addition, when we conducted a component analysis on the above sample 1, we found that the second
The results shown in the table were obtained.

As is clear from the component analysis results shown in Table 2, Sample 1 is composed mainly of stable inorganic substances such as silicic acid (Stow) and aluminum oxide (AItoz), which are common soil components. Even if buried in the surrounding area, it will easily blend into the surrounding soil (and will not change easily).

Next, sample 2 of the grounding material according to the first invention was prepared by mixing 25% (weight ratio) of Portland cement or 29% (weight ratio) of carbon powder based on the above-mentioned sample 1. This was designated as sample 3.

Sample 2 above. Sample 3 is obtained by mixing non-polluting substances such as Portland cement or carbon powder with Sample 1, and therefore, like Sample 1, there is no concern about pollution.

The electrical resistivity characteristics of Samples 2 and 3 when they were hydrated were measured and are shown in FIG. 1(B).

The results shown in (C) were obtained.

As is clear from the measurement results in Figures 1 (B) and (C),
The above sample 2 and the above sample 3 have an electrical resistivity of 50 (Ω-m) or less when the water content is 20%, and an electrical resistivity of about 5 [Ω-m] when the water content is 50%, The electrical resistivity was approximately half that of Sample 1 with the same water content.

Here, the reason why Sample 2 and Sample 3 have low electrical resistivity when hydrated is not limited to the case where Portland cement or carbon powder is mixed in at the above-mentioned ratio, but when the mixing ratio is changed. As is clear from Figures 2 and 3, which show the electrical resistivity, as the proportion of Portland cement or carbon powder in the sample increases, the electrical resistivity of each of the above samples decreases, and this tendency is consistent with each of the above samples. The lower the water content, the more noticeable it becomes.

From the above results, Sample 1 has a low electrical resistivity when hydrated, and by mixing Sample 2 with Sample 2, an even lower electrical resistivity can be obtained.Moreover, there is no need to worry about pollution even if buried underground. Because it has properties such as being easy to blend in with the surrounding soil and being resistant to deterioration, it can be expected to be extremely effective when used as a grounding material.

Here, the above sample 1. The calcined sludge used in Samples 2 and 3 was obtained by sludge treatment as shown in FIG. 4 at a water purification plant. In the sludge treatment at this water treatment plant,
The sludge containing a large amount of water, which has settled in sedimentation ponds etc. through water treatment, is made into thick muddy water through concentration process 2, and flocculant etc. The resulting product is incinerated 5a with natural gas 6 in a direct-fired furnace 5 and dried 5b to obtain a fired product 7. Note that the water separated in the concentration treatment step 2 is discharged. The exhaust gas generated from the direct-fired furnace 5 is discharged into the atmosphere after dust is removed by a dust removal device 8. Also,
The above-mentioned fired product 7 is usually disposed of as a scrap car, so it can be obtained at low cost.

Incidentally, it is also possible to use a burned product of sludge mixed with wood chips activated carbon for the purpose of deodorizing or the like during water treatment in a water purification plant as the grounding material according to the first invention.

In the above-mentioned example, a sample of a calcined sludge obtained from a water treatment plant and a sample in which Portland cement or carbon powder was mixed into the calcined sludge was used. It is not limited to a fired product that mainly consists of the fired sludge obtained from other water treatment facilities, but it is also possible to use a fired product that has been incinerated from sludge obtained from other water treatment equipment. For the purpose of increasing or maintaining various grounding material properties such as corrosion protection or increasing compressive strength, substances other than the above-mentioned Portland cement and carbon powder may be mixed into the above-mentioned fired product, or the particle size and shape of the above-mentioned fired product or mixed materials may be changed. It may be changed.

(C-2) Example of grounding structure An embodiment of the grounding structure according to the second invention is shown in FIG.

In FIG. 5, the grounding structure 50 includes a soil layer 5 made by adding, for example, the above-mentioned sample 1 to the site of the grounding equipment 51 as a grounding material mainly composed of burned sludge obtained by water treatment.
2, and a linear or plate-shaped ground electrode 53 connected to the grounding equipment 51 and buried in the soil layer 52.

Here, in the grounding structure 50, a very large pseudo-grounding body layer covering the grounding electrode 53 is formed of the above-mentioned soil layer 5 having a low electrical resistivity.
2, the grounding equipment 51 can be grounded with a sufficiently low grounding resistance, and there is no risk of the pseudo grounding layer being washed away by rainwater or groundwater, and the grounding resistance can be maintained at a sufficiently low level for a long period of time. The grounding effect is great as it can be obtained over a wide area.

Furthermore, since the soil layer 52 is formed using the sample 1, it is economical and there is no concern about pollution.

Here, in order to form the above-mentioned soil N52, a hole dug for burying the above-mentioned grounding electrode 53 and the above-mentioned grounding equipment 51 are required.
Sample 1 is a large backfill excavated for foundation work, etc.
Alternatively, the samples 1 may be piled up on the site of the grounding equipment 51.

Another embodiment of the grounding structure according to the second invention is shown in FIG.

In FIG. 6, a grounding structure 60 includes a linear or plate-shaped grounding electrode 62 connected to a grounding equipment 61, a first soil layer 63 in which the grounding electrode 62 is buried, and a first soil layer 63 in which the grounding electrode 62 is buried. A second layer of soil was added to the site of the grounding equipment 61 to cover the layer.
It is composed of a layer of soil 64. For the first and second soil layers 63 and 64, for example, Sample 1 is used as a grounding material mainly composed of burned sludge obtained by water treatment. Grounding materials with small particle diameters that have been pulverized using a ball mill or the like are used.

Here, the grounding structure 60 uses a grounding material with a small particle size for the first soil N63 to improve the adhesion of the ground electrode 62 and increase the grounding effect, and furthermore, the first soil By forming a very large pseudo-grounding layer with the second soil M64 having a low electrical resistivity covering the layer 63, the grounding equipment 61 can be grounded with sufficiently low grounding resistance, and rainwater There is no risk of the pseudo-grounding layer being washed away by water or groundwater, and sufficiently low grounding resistance can be obtained over a long period of time, resulting in great grounding effects. In addition, the first and second soil layers 63.64 include the sample 1 and the sample 1.
It goes without saying that it is economical and there is no concern about pollution because it uses a grounding material with a small particle size that has been pulverized.

In addition, the above-mentioned first and second land J! At 63.64,
As mentioned above, various grounding materials can be used without departing from the spirit of the invention. especially,
The grounding material used for the first soil layer 64 may be a grounding material different from that of the second soil layer 63 that has been pulverized. Grounding materials mixed with various substances or having different particle sizes and shapes may also be used.

Next, an embodiment of the grounding structure according to the third invention is shown in FIG.

In FIG. 7, a grounding structure 70 is composed of a rod-shaped grounding electrode 80 connected to a grounding equipment 71, and a grounding layer 72 in which the grounding electrode 80 is vertically buried.

Here, as shown in FIG. 8(A), the ground electrode 80 is attached to the rear end of a single ground rod 83, which is hollow and has a number of protrusions 82 around its circumference, and has a conical plunge member 81 attached to its tip. A lead wire deriving member 85 is attached to which a lead wire 84 connected to the grounding equipment 71 is connected, and as shown in FIG. A single ground rod 83, which is hollow and has a number of holes 87 around its circumference, is connected in communication with the ground rod 83 to change its length. In addition, the ground layer 72
In the process of driving the grounding electrode 80 almost vertically into the site of the grounding equipment 71 with an electric hammer or the like, for example, the rear end of the samples 1 and 88 is used as a grounding material mainly composed of burned sludge obtained by water treatment. It is formed by pouring it into the ground around the ground electrode 80 through the holes 82, 87 around the ground rod 83, 88.

Therefore, in the grounding structure 70, the grounding electrode 80
A very large pseudo-grounding layer covering the grounding layer 72 having a low electrical resistivity is formed, and the grounding equipment 71 can be grounded with sufficiently low grounding resistance, and can maintain sufficiently low grounding resistance for a long period of time. It has a great grounding effect. Furthermore, since the sample 1 is used for the ground layer 72, it goes without saying that it is economical and there is no concern about pollution.

The ground structure 70 is constructed by forming the ground 11i72 while performing poling using a grounding material prepared by dissolving the sample 1 in water and making it fluid, as a lubricant, and inserting a rod-shaped ground electrode into the hole made by the poling. It can also be formed by inserting.

The grounding material used for the grounding layer is not limited to Sample 1, and as described above, various materials can be used without departing from the spirit of the present invention. Effect of the H1 Invention In the first invention, water treatment By using the fired sludge obtained as the main ingredient, it is possible to obtain a grounding material that exhibits low electrical resistivity when hydrated and is harmless to humans and animals.

In the second aspect of the invention, grounding can be performed effectively and economically by burying a grounding electrode using a grounding material mainly composed of burned sludge obtained through water treatment.

In the third invention, a grounding material mainly composed of burned sludge obtained through water treatment is dissolved in water and injected around a buried grounding electrode to form a grounding layer, thereby effectively and economically grounding. It can be carried out.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the electrical resistivity of a sample used in an example of the first invention when it contains water, and Figure 2 shows the relationship between the proportion of Portland cement mixed in the sample and the electrical resistivity. Figure 3 is a characteristic diagram showing the relationship between the proportion of carbon powder mixed in a sample and electrical resistivity, Figure 4 is a process diagram explaining sludge treatment at a water treatment plant, and Figure 5 is FIG. 6 is a grounding structure diagram showing an embodiment of the second invention; FIG. 7 is a grounding structure diagram showing another embodiment of the second invention; FIG. 7 is a grounding structure diagram showing an embodiment of the third invention. Structure diagram, FIG. 8 is a schematic diagram showing the structure of the rod-shaped electrode used in the embodiment shown in the seventh leap,
FIG. 9 is a schematic diagram showing a conventional grounding structure. 51.61.71...Grounding equipment 53.62.80...Grounding electrode 52.63.64...Soil layer 72...Ground layer Patent applicant Murata Electric Manufacturing Co., Ltd. Agent Patent attorney Small Ike Mima 1) Village Article - Figure 1 Figure 2 Figure 3 Figure 5 / Same Day Al”!
Circle Figure 6 Figure 9

Claims (6)

[Claims] (1) Grounding material mainly made of burned sludge obtained through water treatment. (2) The grounding material according to claim 1, characterized in that portland cement is mixed into the fired product. (3) The grounding material according to claim 1, wherein carbon is mixed into the fired product. (4) A grounding structure characterized in that a grounding electrode is buried in a layer of grounding material made mainly of burned sludge obtained through water treatment at the site of the grounding equipment. (5) The grounding structure according to claim 4, wherein a grounding material having a small particle size obtained by pulverizing the fired product is used around the grounding electrode. (6) A grounding structure characterized in that a grounding layer is formed by dissolving a grounding material mainly composed of burned sludge obtained through water treatment and injecting it around a buried grounding electrode.