JPH0855645A - Earthed electrode - Google Patents

Abstract

PURPOSE:To provide a high performance earthed electrode capable of simply executing within a limited land area at low cost and obtaining specified earthing resistance. CONSTITUTION:An earthed electrode has an earthing conductive wire 11, a metal net 12 connected to the earthing conductive wire 11, and an earthed mixture 10. The mixture 10 has cement and EP ash particles mixed and dispersed to the cement. Since the contact surface with soil forms uniform mixed harmonized contact, different from the point contact with a metal electrode, contact resistance of the earthed electrode with the surrounding soil is remarkably decreased, and the surface area of the earthed electrode is increased, and the earthing resistance decreasing effect is remarkably increased. The executing area necessary for decreasing the earthing resistance is decreased, the executing amount of the earthed electrode for obtaining the low earthing resistance is also decreased, and the execution capability of the earthed electrode is enhanced. Since the low cost EP ash particles which are industrial waste is used, raw material cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground electrode used for electrically grounding electric equipment of various electric facilities.

[0002]

2. Description of the Related Art Generally, a ground electrode for grounding an electric device of this electric equipment to the ground is buried near the electric equipment such as a power station, a substation, or a steel tower in a transmission line. As such a ground electrode, a metal ground electrode mainly made of copper has been conventionally used. This metal ground electrode is buried in the ground and connected to an electric device via a ground conductor.

[0003]

When a ground electrode made of metal is used in a place where the earth resistivity is high, the limit point of the reduction ratio of the ground resistance is high. Therefore, in order to obtain a predetermined ground resistance, a construction area is required. However, there was a problem in that it was necessary to acquire a large site because of the large size of the land, and a large amount of money was required for grounding work.

Further, in recent years, a ground electrode made of conductive concrete formed by mixing carbon-based powder with cement has been proposed instead of these metal electrode rods. However, since the ground electrode made of conductive concrete described above uses expensive special sintered carbon or carbon fiber as the main raw material, there is a problem that the raw material cost of the ground electrode becomes high.

The present invention effectively solves the above problems, and provides a ground electrode which improves the workability of the ground electrode, can be constructed at a low cost, and can obtain a predetermined ground resistance. With the goal.

[0006]

The grounding electrode of the present invention has a grounding conductor connected to electric equipment of various electric facilities, and a mixture grounded while being connected to the grounding conductor. The mixture has cement and EP ash granules dispersed and mixed in the cement. It is preferable that the EP ash particles have a particle size of 2 to 6 mm. A wire mesh may be provided to connect the mixture to the ground conductor.

[0007]

In the ground electrode of the present invention, the electric equipment of the electric equipment is grounded to the ground through the grounding conductor and EP ash particles. The cement in the mixture is hardened by adding water.

The ground electrode of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the ground electrode is a wire net 11 buried in the ground near an electric facility, and a grounding wire 12 arranged in the wire net 11 and connected to the wire net 11 and electric equipment of the electric facility. And these wire mesh 1
1 and the grounding wire 12 and a mixture 10 covering the circumference thereof. This mixture has EP ash granules and cement.

Industrial waste discharged from a power plant or the like is used as the EP ash particles. Here, EP (Electron Par
Ashes are ash particles that are generated at power plants. The particles of the EP ash itself are very fine, and in order to effectively utilize 80% or more of the carbon content contained in this EP ash to enhance the conductivity, EP ash granules formed by forming EP ash into large particles are used. There is. That is, the EP ash particles have a particle size of 2 m.
If it is less than m, the conductivity is lowered, which is not preferable, and if the particle size exceeds 6 mm, it is not preferable because the workability during construction is deteriorated.

EP ash granules are manufactured by the following manufacturing method. First, EP ash is mixed with a starch-based glue or a glue-based glue to form a pellet-shaped or block-shaped molded product. By inserting this into a high-temperature furnace with air cut off and heating it, the starchy or colloidal glue is completely carbonized and E
Use P ash particles. Here, in the case of a molded product having a particle size of more than 6 mm, it is crushed to a particle size of 6 mm or less to obtain EP ash particles. As a result of the experiment, the electric resistivity values of the molded product using the starch-based glue and the molded product using the glue-based glue are almost the same, but after the cement is mixed and cured, The electrical resistivity and compressive strength of the molded product using the glue of the colloidal system are superior.

The cement used here may be a commercially available cement, for example, Portland cement, early-strength cement, alumina cement, jet cement, blast furnace cement or the like. Not limited. The blending ratio of these EP ash granules and cement is not particularly limited as long as the conductivity of these mixtures can be maintained. Also, for example, cement 50
% By weight and 50% by weight of EP ash granules may be mixed to form a mixture.

The ground electrode is provided in the excavation trench as a strip electrode having a thickness of about 2 to 4 cm, and
The method can be effectively used for both a deep-buried electrode method and a method of filling a boring hole excavated by a boring machine, but is not particularly limited to these methods.

In the ground electrode according to the present invention, the contact surface with the soil is different from the point contact state of the metal electrode, and a uniform mixed and compatible contact is obtained, so that the contact resistance between the ground electrode and the surrounding soil is extremely small. Further, since the surface area of the ground electrode can be made large, the ground resistance reducing effect is very large. Therefore, the construction area required for reducing the ground resistance can be reduced, and the construction amount of the ground electrode for obtaining the low ground resistance can be reduced, and the construction workability of the ground electrode can be improved.
The ground electrode according to the present invention uses inexpensive EP ash particles and cement, which are industrial wastes, as compared with expensive special sintered carbon, so raw material cost can be reduced and construction work cost of the ground electrode can be significantly reduced. In addition, since it does not contain harmful substances, there is no concern about environmental pollution and it can be useful for environmental protection.

The EP ash granules and cement are
Compared to metallic materials, it is less likely to rust due to oxidation or the like, and it is possible to eliminate the need for rust prevention treatment, and it is stable at room temperature, so it can withstand long-term use. Further, the specific resistance and strength of the ground electrode according to the present invention can be set to arbitrary values by changing the blending ratio of cement to be blended. Further, according to the present invention, by bringing the wire net into contact with the grounding conductor and the mixture, the grounding resistance can be further reduced as compared with the case where only the grounding conductor and the mixture are used as the ground electrode.

[0015]

【Example】

(Experimental Example 1) Next, the specific resistance and compressive strength of the ground electrode of the present invention are measured. Mixing ratio, specific resistance, and compressive strength Mixing ratio (weight ratio total amount 2,000g) EP ash granules 1,000g weight ratio 50% cement 1,000g weight ratio 50% Add 600g of water at the above mixing ratio Physical test method JIS R5201-1992 compressive strength is 4
It is 39 kg / cm ² , and the specific resistance of the same sample is 0.9 Ω / m.

(Experimental Example 2) First, EP ash granules are made into a block-molded product by using a glue of a glue type, which is heated and carbonized to form EP ash granules having a particle size of 2 to 6 mm. This E
A mixture is prepared by mixing 50% by weight of P ash granules and 50% by weight of cement. Next, as shown in FIG. 1, this mixture 10 was applied on the ground surface to a width 500 shown in the plan view of (a).
mm, thickness 30 to 50 mm, depth 1000 mm, length 1
Embed over 0000 mm. At this time, the mixture 1
220 mm wide and 10000 long at a position almost in the middle of 0
mm wire mesh 11 is arranged, and the grounding conductor 1 is placed on the wire mesh 11.
Arrange the two bonded together. As the grounding conductor 12, an annealed copper stranded wire having a sectional area of 60 mm 2 was used.

(Comparative Example 1) As a ground electrode, as shown in FIG. 2, the same grounding conductor 12 as in Experimental Example 2 was directly buried,
Buried ground line. (Comparative Example 2) As a ground electrode, as shown in FIG.
Four rod electrodes 5 of mmφ × 1.5 m are placed in parallel in a substantially vertical direction. The connecting bare copper wires 6 for four parallel connections are connected to the upper ends of the rod electrodes 5.

(Experimental Example 3) Mixture 10 similar to Experimental Example 2
As shown in the sectional view of FIG. 4 (a), a width of 500 mm,
It is buried over a length of 10000 mm and is shown in FIG.
As shown in the plan view of (b), it is embedded in a thickness of 30 to 50 mm. At this time, a grounding conductor 12 similar to that of Experimental Example 2 is arranged at a position approximately in the middle of the mixture 10.

Table 1 shows the test results of the steady-state ground resistance measurement results and the ground resistance reduction rate in these Experimental Examples 2-3 and Comparative Examples 1-2, and the transient ground resistance (surge impedance).
Table 2 shows the measurement results of the reduction rate.

[0020]

[Table 1]

[0021]

[Table 2]

As is clear from the results shown in Table 1, Experimental Examples 2 and 3 showed a large reduction rate of steady ground resistance as compared with Comparative Examples 1 and 2, and in particular, the experiment using the mixture and the wire mesh together. The steady-state ground resistance reduction rate of Example 2 is large, and then decreases in the order of Experimental Example 3 using the mixture.

Further, as is clear from the results of Table 2, Experimental Examples 2 and 3 show a large reduction rate of transient earth resistance as compared with Comparative Examples 1 and 2, and in particular, the mixture and the wire mesh are used together. The reduction rate of the transient ground resistance in Experimental Example 2 is large, and then decreases in the order of Experimental Example 3 using the mixture. Although the ground resistance can be greatly reduced even when only the ground conductor and the wire mesh are used as the ground electrode, the ground resistance can be further reduced by connecting a mixture of EP ash particles and cement to this.

[0024]

As described above, according to the ground electrode of the present invention, the ground conductor connected to the electric equipment of various electric facilities and the mixture grounded while being connected to the ground conductor. This mixture has cement and EP ash granules dispersed and mixed in this cement,
Unlike the point contact state of the metal electrode, the contact surface with the soil is a uniform mixed and compatible contact, so the contact resistance between the ground electrode and the surrounding soil is extremely small. Further, since the surface area of the ground electrode can be made large, the ground resistance reducing effect is very large. Therefore, the construction area required for reducing the ground resistance can be reduced, and the construction amount of the ground electrode for obtaining the low ground resistance can be reduced, and the construction workability of the ground electrode can be improved. The ground electrode according to the present invention uses inexpensive EP ash particles and cement, which are industrial wastes, as compared with expensive special sintered carbon, so raw material cost can be reduced and construction work cost of the ground electrode can be significantly reduced. In addition, since it does not contain harmful substances, there is no concern about environmental pollution and it can be useful for environmental protection.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a ground electrode of Experimental Example 2 of the present invention.

2 is a configuration diagram showing a ground electrode of Comparative Example 1. FIG.

FIG. 3 is a configuration diagram showing a ground electrode of Comparative Example 2.

FIG. 4 is a configuration diagram showing a ground electrode of Experimental Example 3 of the present invention.

[Explanation of symbols]

 10 mixture 11 grounding wire 12 wire mesh

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Haruaki Ito 8-6 Minamisumiyoshi, Tokorozawa-shi, Saitama Prefecture (72) Inventor Kazuhiro Toguri 135-1 Kumadawa, Kushigata-cho, Nakakoma-gun, Yamanashi Prefecture

Claims (3)

[Claims] 1. A grounding conductor connected to electric equipment of various electric facilities, and a mixture grounded while being connected to the grounding conductor. The mixture is dispersed in the cement and the cement. A ground electrode comprising: a blended EP ash granule. 2. The ground electrode according to claim 1, wherein the EP ash particles have a particle size of 6 mm or less. 3. The ground electrode according to claim 1, further comprising a wire mesh connected to the mixture and the ground conductor.