WO1996005631A1

WO1996005631A1 - Earth electrode

Info

Publication number: WO1996005631A1
Application number: PCT/JP1995/001623
Authority: WO
Inventors: Hisao Gozu; Haruaki Ito; Kazuhiro Toguri
Original assignee: Hokuriku Electricpower Company; Hagihara Boring Company; Tokyo Elicon Co., Ltd.
Priority date: 1994-08-16
Filing date: 1995-08-15
Publication date: 1996-02-22
Also published as: JPH0855645A

Abstract

An earth electrode has an earth conductor (11), a metal net (12) connected to the conductor, and an earthed mixture (10). This mixture (10) contains cement, and EP ash particles dispersed in and blended with the cement. As a result, the surface of the earth electrode which contacts the earth in a uniform mixed harmonized condition different from the point contact of a metal electrode. Therefore, the contact resistance between the earth electrode and the surrounding soil is very low. The surface area of the earth electrode can be large, so that the earthing resistance reduction effect is good. The work area required to reduce the earthing resistance can be small, the work of installing the earth electrode can be reduced, and the workability of the earth electrode can be improved. Moreover, since inexpensive EP ash particles, industrial waste, are used, the raw material cost can be reduced.

Description

Mei Rui Title of the invention Ground electrode Background technology

Generally, a ground electrode for grounding the electric equipment of the electric equipment to the ground is buried near a power plant, a substation, or an air facility such as a steel tower in a transmission line.

As such a grounding electrode, a metal grounding electrode mainly using copper has conventionally been used. This metal ground electrode is buried in the ground and is connected to an electrical equipment via a ground conductor.

Where the ground resistivity is high, when a metal ground electrode is used, the critical point of the reduction ratio of the ground resistance is high, and the construction area for obtaining a predetermined ground resistance becomes large. As a result, there were problems such as the necessity of acquiring a large land and the necessity of enormous costs for grounding work.

In recent years, a grounding electrode made of conductive concrete formed by mixing carbon purple powder with cement has been proposed in place of the rod-shaped electrode made of a metal material. I have. However, the above-mentioned ground electrode made of conductive concrete uses expensive waiting sintered carbon or carbon fiber as a main raw material, so that the raw material cost of the ground electrode becomes high. was there. Disclosure of the invention

The present invention effectively solves the above-mentioned problems, and provides a ground electrode capable of improving the workability of grounding electrodes, being constructed at low cost, and obtaining a predetermined ground resistance. It is intended to provide.

It is preferable that the ash granules form a grain of 2 to 6 mm.

A wire mesh may be provided for contacting the mixture and the ground conductor.

In the grounding electrode of the present invention, the air equipment of the electric equipment is grounded to the ground through a grounding conductor and EP ash particles. The cement in the mixture is cured by adding water.o Hereinafter, the ground electrode of the present invention will be described with reference to the drawings. As shown in Fig. 1, the grounding electrode is a wire mesh 11 buried in the ground near the electrical equipment, and placed in the wire mesh 11, and the wire mesh 11 and the electrical equipment It has a ground wire 12 connected to the air-conditioning equipment, and a mixture 10 surrounding the wire mesh 11 and the ground wire 12. This mixture has EP syrup and cement.

Industrial waste discharged from the source etc. is used for EP ash granules. Here, E P (Electron P art i c l e) ash is charged particles generated in the power plant.

The particles of EP ash itself are very fine, and EP ash particles, in which EP ash is formed into large particles, are used to effectively utilize the carbon content of 80% or more contained in this EP ash to increase conductivity. Have been.

That is, when the particle size of EP ash particles is 2 mm or less, the conductivity becomes low.Therefore, it is not preferable, and when the abduction exceeds 6 mm, workability at the time of construction deteriorates. Not good for that reason.

EP ash granules are manufactured by the following manufacturing method.

First, the ash powder is mixed with the ash-like glue or the knee-like glue to form a pellet or block-like molded product. This is introduced into a high-temperature furnace in which the air is shut off, and heated to completely carbonize the cutting or glue paste to form EP ash granules.

In this case, if the abducted product exceeds 6 mm, it should be crushed into less than 6 mm abducted to make EP ash granules.

Experimental results show that the molded articles using these powder-killing pastes and the molded articles using the colloidal pastes have almost the same air resistivity values. The molded article using the colloidal glue has better air resistivity and compressive strength after curing. Here, the cement used can be a commercially available cement, for example, a vault land cement, an early strong cement, a mineral cement, Jet cement, Takai cement and the like can be mentioned, and the kind of these cement is not particularly limited. The mixing ratio of the EP torment and cement is not particularly limited as long as the conductivity of these mixtures can be maintained.

Further, for example, 50% by weight of cement and 50% by weight of EP ash granules may be mixed to form a mixture. In addition, this ground electrode is applied to the obi-bushi pole method, which is provided as an electrode with a thickness of about 2 to 4 cm in the digging trench, and to the boring hole excavated by a boring machine. It can be used effectively for both deep burial and polar construction methods, but it 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 uniform mixed fusion welding is performed, so that the contact resistance between the ground electrode and the surrounding soil is extremely small. .

Further, since the take rather large surface area of the ground electrode, _c therefore is very large grounding resistance reduction effect can be rather small the construction area required to low, dropping the ground resistance, In addition, since the low grounding resistance acquisition The installation of the ground electrode can be reduced, and the workability of the ground electrode can be improved.

The ground electrode according to the present invention uses inexpensive EP ash and cement, which are industrial wastes, as compared with expensive special sintered carbon and the like, so that the raw material cost can be reduced, and the ground electrode can be reduced. Construction costs can be significantly reduced. In addition, since it does not contain harmful substances, it can be used for environmental protection without concern for environmental pollution.

In addition, these EP ash bodies and cements are more susceptible to oxidation and the like than metal materials, and can eliminate the need for heat protection treatment, and are stable at room temperature. Therefore, it can withstand long-term use.

The specific resistance and strength of the ground electrode according to the present invention can be set to any numerical values by changing the mixing ratio of the cement to be mixed.

Further, in the present invention, by bringing the wire net into contact with the ground conductor and the mixture, the ground resistance can be further reduced as compared with the case where only the ground conductor and the mixture are used as the ground electrodes. BRIEF DESCRIPTION OF THE FIGURES

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

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

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

FIG. 4 is a configuration diagram showing a ground electrode of Experimental Example 3 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Experimental example 1

First, the specific resistance and compressive strength of the mixture used for the ground electrode of the present invention were measured.o

Mixing ratio, specific resistance, and compressive strength of the mixture

Mixing ratio (total weight 2,000 «)

Ρ Ρ 拉拉体 1, 0 0 0 g Weight ratio 50%

Cement l, 0 000 g Weight ratio 50%

Method of physical test of cement with ground electrode to which 600 g of water was added at the above ratio E

The compressive strength according to ISR 5201 — 1992 was AS gkg Z cm ² , and the specific resistance of the same sample was 0.9 Ω / πι.

Experimental example 2

The ep ash body was made into a block molded product using knee-like glue, which was heated and carbonized to form ep ash particles having a particle size of 2 to 6 mm. A mixture was obtained by mixing 50% by weight of this ep ash body and 50% by weight of cement.

Next, as shown in FIG. 1, this mixture 10 was placed on the ground surface at a width of 500 mm, a thickness of 30 to 50 mm, and a depth of 100 mm as shown in the plan view of (A). It was buried over a length of 0 mm and a length of 1000 mm. At this time, a wire net 11 having a width of 220 mm and a length of 1000 mm was placed at a position almost in the middle of the mixed base 10, and a ground wire 12 was placed on the wire net 11. Were placed in a state where they were attached to each other. The ground conductor 1 2 This was used钦鋼strand cross-sectional area 6 0 mm ^2.

Comparative example 1

As shown in Fig. 2, a grounding conductor 12 similar to that in Experimental Example 2 was directly buried as the grounding electrode, and was used as a buried ground wire.

Example 2

As shown in Fig. 3, four 14 mm?> Xl .5 m poles 5 are placed almost vertically in parallel with each other as the ground 接地, and the upper ends of these poles 5 The connection was made with a bare copper wire 6 for connection for four parallel connections.

Example 3 As shown in the cross-sectional view of FIG. 4 (A), a mixture 10 similar to that of Experimental Example 2 was embedded over a width of 500 mtn and a length of 100 mm, and the mixture 10 As shown in the plan view of (B), it was embedded to a thickness of 30 to 50 mm. At this time, the ground conductor 12 similar to that of the experimental example 2 was EE at a position almost in the middle of the mixture 10.

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

Table 1 Steady grounding Steady grounding resistance reduction rate (%)

Resistance (Ω)

Comparative example 1 Comparative example 2 Experimental example 3 Comparative example 1 1 8.4 Comparative example 2 1 7. 3.5.9 8 Experimental example 3 6. 8 6 3. 0 4 6 0, 6 9 Experimental example 2 4. 6 7 5, 0 0 7 3. 4 1 3 2. 3 5

Table 2

As is evident from the results in Table 1, Experimental Examples 2 and 3 show a large ground-fault steady contact resistance reduction rate compared to Comparative Examples 11 and 2, and in particular, the results obtained when the mixture and wire mesh were used together. steady ground resistance low减率of联例2 large active, then混台was small Ku of the order of experiment example 3 using ₀

In addition, as is clear from the results in Table 2, Experimental Examples 2 and 3 showed a large reduction rate of the transient grounding resistance as compared with Comparative Examples 1 and 2, and in particular, experiments using the mixture and the wire mesh The transient grounding resistance low frequency ratio in Example 2 was large, and then decreased in Experimental Example 3 using the mixture.

The grounding resistance can be greatly reduced by using only the grounding conductor and the wire mesh as the grounding electrode, but this can be achieved by contacting a mixture of limestone and cement. Further, the ground resistance can be reduced.

As described above, the ground electrode of the present invention has a ground conductor connected to electrical equipment of various electric facilities, and a mixture connected to the ground conductor and grounded. Has cement and ash granules dispersed and blended in the cement. As a result, the contact surface with the soil is different from the point contact state of the metal electrode, The contact resistance between the ground electrode and the surrounding soil becomes very small due to mixed hydrated contact. <Also, since the surface area of the ground electrode is large, the effect of reducing the ground resistance is very large, and therefore, The work area required to reduce the ground resistance can be reduced, and the installation of the ground electrode for obtaining a low ground resistance can be reduced, and the workability of the ground electrode can be improved. .

In addition, the ground electrode according to the present invention uses inexpensive EP ash and cement, which are industrial wastes, as compared with expensive special sintered carbon and the like, so that the raw material cost can be reduced and the ground electrode can be reduced. The construction cost can be greatly reduced, and since it does not contain harmful substances, there is no need to worry about environmental pollution and it can be used for environmental conservation.

Claims

The scope of the claims

1. It has a grounding conductor connected to the S equipment of various electric facilities, and a mixture that is connected to the grounding conductor and is grounded. A grounding electrode characterized by having EP ash granules dispersed and blended in the cement.

2. The above-mentioned EP ash granules are characterized in that their diameter is formed to 6 mm or less.

3. The ground electrode as described in Paragraph 1 or 2 above, wherein the kidnapping body is characterized in that the kidnapping is formed to 2 mm or more.

4. The ground electrode according to any one of claims 1 to 3, wherein a wire mesh is provided for contacting the mixture with a ground conductor.

5. The method according to any one of claims 1 to 4, wherein the EP ash body is a charged abduct discharged from a power plant or the like as industrial waste. Ground electrode as described.