JP2008112683A - Earthing arrangement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an earthing arrangement which can be laid in the ground without having influence on adjacent buried objects. <P>SOLUTION: An earth electrode body 11 is formed into a cylindrical body, and has a length shorter than an earthing pin, a diameter larger than that of the eathing pin, and a surface area equivalent to the surface area of the earthing pin, and a reinforcement material 13 is provided in the cavity part 12 of the earth electrode body 11. Thereby, the earth electrode body 11 is not required to be laid deep in the ground, an earthing resistance can be installed in a short time. In addition, since the earth electrode body 11 has the surface area equivalent to the surface area of the earthing pin, an earthing resistance value can be made almost equivalent to that of the earthing pin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a grounding device for grounding a device such as an electric device, a communication device, or a lightning arrester.

  In general, electrical equipment and communication equipment are grounded by a grounding rod through lead wires. For example, in grounding a cable in a power hand hole (underground concrete structure), the cable is grounded by a grounding rod through a lead wire in the manhole. In the construction of such a grounding rod, when a new manhole is constructed, the grounding rod is inserted into the ground on the ground side outside the housing so that the lead wire can be passed inside the housing. In the case of an existing manhole, the casing is drilled from the inside of the manhole and the grounding rod is inserted.

The grounding rod can be driven very easily without digging the ground even in a narrow grounding site. There is one that can perform the driving operation consistently (see, for example, Patent Document 1).
JP 2000-164321 A

  However, in new manholes buried in roads, in recent years, existing buried objects (gas pipes, water pipes, communication lines, etc.) may become congested, and it may not be possible to secure a space for installing grounding rods. Further, even if one grounding rod can be installed, if the grounding resistance value cannot fall below a desired value, a plurality of grounding rods will be placed. It may be difficult to secure a place to install the grounding rod.

  On the other hand, in existing manholes, especially in old brick manholes, the standard value set by law is satisfied due to the effects of corrosion of the grounding rod due to aging, but the grounding resistance value is higher than the original value. There are manholes that are also rising. In such a case, a ground rod is installed by drilling a part inside the manhole. However, the work space is often restricted due to the existence of an existing cable, and the construction is often difficult.

  In addition, when underground facilities such as water supply facilities and communication facilities are provided near the manhole, the grounding rod cannot be easily installed in the ground. Because the grounding rod is usually 14 to 25 mm in diameter and about 1500 mm in length, if the grounding rod is easily placed, there is a risk of damage to underground facilities such as nearby water and communication facilities. Because there is. In addition, when there is an underground buried object in the vicinity, it may be difficult to secure a space for placing the grounding rod, and it may be difficult to install while avoiding the underground buried object.

  An object of the present invention is to provide a grounding device that can be easily installed in the ground without affecting adjacent buried objects and can obtain a desired grounding resistance value.

  According to a first aspect of the present invention, there is provided a grounding device having a shorter length and a larger diameter than a grounding rod and having a surface area equivalent to a surface area of the grounding rod. And a reinforcing material provided in the case.

  According to a second aspect of the present invention, there is provided a grounding device having a shorter length and a larger diameter than a grounding rod and formed in a cylindrical body, and having a surface area equivalent to the surface area of the grounding rod; And a protrusion provided in the axial direction of the cylindrical body on the outer peripheral surface of the grounding electrode main body.

  According to a third aspect of the present invention, there is provided a grounding device that is shorter than the grounding rod and has a large diameter and is formed in a cylindrical body having a surface area equivalent to the surface area of the grounding rod; And a cut-and-raised claw cut and raised in the axial direction of the cylindrical body on the outer peripheral surface of the ground electrode.

  According to the present invention, the grounding electrode body is formed in a cylindrical body, and is shorter and larger in diameter than the grounding rod. Therefore, it is not necessary to lay the grounding electrode body deep in the ground, and can be installed in a short time. . Moreover, since the grounding electrode body has a surface area equivalent to the surface area of the grounding rod, the grounding resistance value can be made comparable to that of the grounding rod, and a desired value can be obtained.

  In addition, when a protruding part or a cut-and-raised claw is provided in the axial direction of the cylinder on the outer peripheral surface of the grounding electrode body, the shape of the protruding part or the cut-and-raised claw is pointed at the tip, so that it is easy to discharge and ground. The resistance value is also reduced. Therefore, the ground electrode body can be formed small.

(First embodiment)
FIG. 1 is a configuration diagram of a grounding device according to a first embodiment of the present invention. FIG. 1 (a) is a top view, FIG. 1 (b) is a side view, and FIG. 1 (c) is a bottom view. . The grounding electrode main body 11 is formed of a conductive member (for example, copper) in a cylindrical body, and FIG. 1 shows an octagonal cylindrical body.

  A reinforcing member 13 is provided inside the hollow portion 12 of the ground electrode body 11 formed in the cylindrical body, and mechanical reinforcement is performed on the ground electrode body 11. An edge portion 14 that covers a part of the cavity portion 12 is provided on the upper surface of the ground electrode body 11. When the ground electrode body 11 is inserted and buried in the ground, soil enters the cavity portion 12, and the cavity portion 12. When the soil enters the entire surface, the soil abuts on the edge portion 14. Therefore, it can be known that the ground electrode main body 11 has been buried because the soil has come into contact with the edge portion 14.

  The rim portion 14 is provided with a lead wire attachment portion 15 for attaching a lead wire, and is connected to the grounding target device by the lead wire. Also, a jagged portion 16 is provided at the bottom of the grounding electrode main body 11 so that when the grounding electrode main body 11 is inserted and buried in the ground, it is easily pierced into the ground and easily discharged toward the ground. I am doing so.

  Next, the size of the ground electrode body 11 will be described. The diameter r2 of the circle inscribed in the grounding electrode main body 11 is 80 mm which is larger than the diameter 14 mm to 25 mm of the grounding rod, and the length L2 of the grounding electrode main body 11 is 150 mm shorter than the length of about 1500 mm of the grounding rod. Yes. Thereby, the surface area equivalent to the surface area of the grounding rod is ensured.

  Here, the surface area S1 of the grounding rod is represented by the approximate expression (1) where the diameter of the grounding rod is r1 and the length is L1.

S1≈πr1 × L1 (1)
On the other hand, the surface area S2 of the grounding electrode main body 11 of the present invention is such that the grounding electrode main body 11 is formed in a cylindrical body and the inner surface of the hollow portion of the cylindrical body is also in contact with the ground. When the length is L2, it is shown by the approximate expression (2).

S2≈ (πr2 × L2) × 2 (2)
As can be seen from the equations (1) and (2), as a rough estimate, when the diameter r2 of the ground electrode body 11 is about five times the diameter r1 of the ground rod, the length L2 of the ground electrode body 11 is set to the ground rod. The surface area S2 of the ground electrode body 11 is equivalent to the surface area S1 of the ground bar.

  When embedding such a grounding device in the ground, for example, a hole for embedding is drilled until the soil is exposed on the existing manhole base. Then, the grounding device is inserted through the hole and pushed into the ground. In this case, the jagged portion 16 at the bottom of the ground electrode main body 11 pierces into the ground, facilitating insertion into the ground. Further, in the process of inserting the ground electrode main body 11 into the ground, the soil enters the cavity 12, and when the soil enters the entire cavity 12, the soil contacts the rim 14. Thereby, it can be known that the burying of the ground electrode body 11 has been completed. Further, when the embedding is completed, the jagged portion 16 is directed toward the inside of the ground, and therefore, it is easy to discharge from the jagged portion 16 toward the inside of the ground.

  According to the first embodiment, the grounding electrode main body 11 is formed in a cylindrical body, the reinforcing member 13 is provided in the cavity 12 of the cylindrical body, and the jagged portion 16 is provided in the bottom of the grounding electrode main body 11. When the ground electrode body 11 is inserted and buried in the ground, the ground electrode body 11 can be easily inserted into the ground without being distorted. Further, since the length is shorter than the grounding rod, it is not necessary to lay the grounding electrode main body 11 deep in the ground, and the work time for installing the grounding resistor can be shortened. Moreover, since the grounding electrode main body 11 has a surface area equivalent to the surface area of the grounding rod, the grounding resistance value can be made comparable to that of the grounding rod.

  Even if this jagged portion 16 is not provided, a ground resistance value comparable to that of the ground bar can be obtained. However, since the effect of further reducing the ground resistance value is generated by the configuration of the jagged portion 16, it is a more preferable mode to have the configuration of the jagged portion 16.

(Second Embodiment)
FIG. 2 is a configuration diagram of a grounding device according to a second embodiment of the present invention. FIG. 2 (a) is a top view, FIG. 2 (b) is a side view, and FIG. 2 (c) is a bottom view. . The second embodiment is different from the first embodiment shown in FIG. 1 in that the cylindrical body of the grounding electrode body 11 is made circular instead of the octagonal shape, and the outer peripheral surface of the grounding electrode body 11 is cylindrical. Protrusions 17 are provided in the axial direction of the body. The same elements as those in FIG.

  As shown in FIG. 2, four projecting portions 17 are provided on the outer peripheral surface of the grounding electrode main body 11 at intervals of a quarter peripheral surface in the axial direction of the cylindrical body. The protrusion 17 is formed in a sawtooth shape, and when the ground electrode body 11 is inserted and buried in the ground, the protrusion 17 functions in the vertical direction while preventing the rotation of the ground electrode 11 and the like. Inserted. When the grounding electrode main body 11 is buried in the ground, the tip of the sawtooth of the protrusion 17 is positioned in the lateral direction in the ground.

  Here, the protrusion 17 is provided in order to further reduce the ground resistance value. In general, as a flow of electricity, discharge tends to occur in a shape portion having a sharp tip. For example, the arc horn for preventing lightning strike on the power transmission tower has a sharp tip, and discharge is performed at this portion to protect the insulator by reverse flashover. Therefore, the cylindrical grounding electrode body 11 is also provided with a serrated projection 17 having a sharp tip so that the charge amount on the surface of the cylindrical grounding electrode body 11 can be easily discharged by the projection 17. The ground resistance value of the pole 11 is made small.

  According to the second embodiment, in addition to the effects of the first embodiment, the protruding portion 17 having a sharp tip is provided on the outer peripheral surface of the ground electrode body 11, and the ground electrode body 11 is embedded in the ground. In some cases, the tip of the projecting portion 17 is positioned in the horizontal direction in the ground, so that it is easy to discharge in the horizontal direction in the ground, and the ground resistance value can be further reduced.

(Third embodiment)
FIG. 3 is a block diagram of a grounding device according to a third embodiment of the present invention, FIG. 3 (a) is a top view, FIG. 3 (b) is a side view, and FIG. 3 (c) is a bottom view. . In the third embodiment, the claw 18 is cut and raised in the axial direction of the cylindrical body on the outer peripheral surface of the ground electrode body 11 with respect to the first embodiment shown in FIG. The same elements as those in FIG.

  As shown in FIG. 3, two cut and raised claws 18 are cut and raised on the outer peripheral surface of the ground electrode body 11 in the vertical direction on the octagonal surface in the axial direction of the cylindrical body. The cut and raised claw 18 is formed in a triangular shape, and when the ground electrode body 11 is inserted and buried in the ground, the cut and raised claw 18 is inserted while scratching the ground. When the grounding electrode main body 11 is buried in the ground, the tip of the cut and raised claw 18 is in a position facing obliquely downward in the ground. The reason why the cut-and-raised claw 18 is provided in the ground electrode body 11 is to further reduce the ground resistance value.

  According to the third embodiment, in addition to the effects of the first embodiment, the cut-and-raised claw 18 having a sharp tip is provided on the outer peripheral surface of the ground electrode body 11, and the ground electrode body 11 is embedded in the ground. In this case, since the tip of the cut and raised claw 18 is located in the obliquely downward direction in the ground, it is easy to discharge in the obliquely downward direction in the ground, and the ground resistance value can be further reduced.

Here, the ground resistance value between the grounding rod and the grounding device in the embodiment of the present invention is compared. First, a grounding rod having the specifications shown in Table 1 was prepared, embedded as shown in FIG. 4, and the grounding resistance value was measured. FIG. 4 is an explanatory diagram of a state where the grounding rod 19 is buried in the ground, and FIG. 4A is an explanatory diagram of a state where the grounding rod 19 is installed near the ground surface in parallel to the ground surface, FIG. 4B is an explanatory view showing a state in which the grounding rod 19 is buried by being driven into the ground in a direction substantially perpendicular to the ground surface.

  That is, a grounding rod having a diameter of 23.7 mm and a length of 1530 mm is used as the grounding rod, and the measurement location is embedded in 150 mm of the ground surface as shown in FIG. The grounding resistance value was measured both in the case where it was placed in the ground as shown in FIG. In this case, the ground resistance is measured by using a ground resistance measuring device disclosed in Japanese Patent Laid-Open No. 2006-234800 that can measure the ground resistance value without laying the P electrode and C power at an interval of 10 m. did. As shown in Table 1, when the ground surface was buried as shown in FIG. 4A, the grounding resistance value of the grounding rod was 29.5Ω. In addition, as shown in FIG. 4 (b), when ground and buried in the ground, the grounding resistance value of the grounding rod was 20.0Ω.

Next, as the grounding device of the present invention, with respect to the specifications shown in Table 2, the grounding device of the first embodiment (without projections) and the grounding device of the second embodiment (with projections) are prepared. As shown in FIG. 5, it was embedded and the ground resistance value was measured. FIG. 5 is an explanatory diagram of a state in which the grounding device 20 of the present invention is buried in the ground. FIG. 5A shows the grounding device (without projections) 20a of the first embodiment to 150 mm near the ground surface. FIG. 5B is an explanatory diagram of a state in which the grounding device (with protrusions) 20b of the second embodiment is embedded in 150 mm near the ground surface.

  That is, as the grounding device of the present invention, a grounding device having a diameter of 80 mm and a length of 150 mm is used, and as shown in FIG. 5A, the grounding device (without projections) 20a of the first embodiment is grounded. Ground resistance in both the case of embedding 150 mm near the surface and the case where the grounding device (with protrusions) 20 b of the second embodiment is embedded in 150 mm near the ground surface as shown in FIG. The value was measured. The ground resistance in this case was also measured using a ground resistance measuring device disclosed in Japanese Patent Application Laid-Open No. 2006-234800. As a result of the measurement, as shown in Table 2, the grounding resistance value of the grounding device (no protrusion) of the first embodiment was 30.0Ω. The grounding resistance value of the grounding device (with protrusions) of the second embodiment was 26.2Ω.

  Comparing the cases where they are buried in 150 mm near the ground surface, the grounding resistance values (30.0Ω and 26.2Ω) of the grounding device of the present invention are almost the same as the grounding resistance value (29.5Ω) of the grounding rod. You can see that it is somewhat small. In this case, the grounding rod has a diameter of 23.7 mm, and the surface area is larger than the surface area of the grounding device of the present invention. Therefore, when viewed relatively, the grounding resistance value of the grounding device of the present invention is highly effective. I can say that. In particular, in the case of the grounding device of the present invention provided with the protrusions 17, it can be seen that the grounding resistance value is clearly reduced as compared with the grounding rod embedded in 150 mm near the ground surface.

  On the other hand, when comparing the case where the grounding rod is placed in the ground and embedded in 1530 mm with the case where the grounding device of the present invention is installed on the ground surface, the grounding resistance value (20.0Ω) of the grounding rod is small. However, the grounding device of the present invention can be sufficiently used as a grounding resistance because the grounding resistance value can be reduced without being buried deep to 1530 mm in the ground.

  If the desired grounding resistance value cannot be obtained due to the soil properties at the location where the grounding device is installed, multiple grounding devices can be installed, or the grounding resistance reducing agent can be added to the backfill soil of the grounding device. Will be used together. Even when a plurality of grounding devices are installed, the grounding device of the present invention does not need to be buried deeply like a grounding rod, and can be easily installed. For this reason, work time is not required significantly.

  Further, when the ground resistance reducing agent is used in combination, the ground resistance value is further reduced. This is because, since the ground resistance reducing agent acts as a pseudo electrode, it acts in a direction in which the diameter of the ground electrode body 11 becomes pseudo-large, so that the ground resistance value is reduced and a desired ground resistance value can be obtained. This is considered to be. When using a grounding rod when using a grounding resistance reducing agent, it is necessary to excavate the soil around the grounding rod to the depth of the grounding rod so that the grounding resistance reducing agent is present around the grounding rod. It took a lot of labor and work time, and it was extremely difficult especially in a place where it was difficult to secure a work space. However, in the present invention, since the ground resistance reducing agent only needs to be present near the ground surface, a large amount of work and work time are not required.

  As described above, when the present invention is used, it is possible to obtain a desired ground resistance value very easily as compared with the prior art.

  Needless to say, this grounding device can be used effectively not only for manholes but also for any underground objects such as caves, troughs, and pipes. It can also be used for grounding an electric work or the like existing on the ground surface.

  In addition, the grounding rod is not limited to the dimensions described in this specification, and the same effect can be obtained by using the device according to the idea of the present invention for the grounding rod having a dimension required conventionally. Needless to say.

The block diagram of the grounding apparatus concerning the 1st Embodiment of this invention. The block diagram of the grounding apparatus concerning the 2nd Embodiment of this invention. The block diagram of the grounding apparatus concerning the 3rd Embodiment of this invention. Explanatory drawing of the state where the grounding rod is buried in the ground. Explanatory drawing of the underground state of the grounding apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Grounding electrode main body, 12 ... Cavity part, 13 ... Reinforcing material, 14 ... Border part, 15 ... Lead wire attaching part, 16 ... Jagged part, 17 ... Projection part, 18 ... Cut-and-raised claw, 19 ... Grounding rod, 20 ... Grounding device

Claims (3)

A grounding pole body having a surface area equivalent to the surface area of the grounding rod, which is shorter than the grounding rod and has a large diameter and is formed into a cylindrical body,
A grounding device comprising: a reinforcing member provided in a cavity of the grounding electrode main body. A grounding pole body having a surface area equivalent to the surface area of the grounding rod, which is shorter than the grounding rod and has a large diameter and is formed into a cylindrical body,
A reinforcing material provided in the cavity of the ground electrode body;
A grounding device comprising: a projecting portion provided in an axial direction of a cylindrical body on an outer peripheral surface of the grounding electrode main body. A grounding pole body having a surface area equivalent to the surface area of the grounding rod, which is shorter than the grounding rod and has a large diameter and is formed into a cylindrical body,
A reinforcing material provided in the cavity of the ground electrode body;
A grounding device comprising: a cut-and-raised claw cut and raised in the axial direction of the cylindrical body on the outer peripheral surface of the grounding electrode.

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