Ground electrode, ground resistance measuring device, and ground resistance measuring method

Abstract

To enable measurement even in a place where an auxiliary grounding rod cannot be driven.SOLUTION: A ground electrode 10 comprises: a plate-like member 60; a holding body 62 that is arranged along one face 60A of the plate-like member 60 and can hold liquid; and a metal grounding net 64 that is arranged superimposed on the holding body 62.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a grounding electrode, a grounding resistance measuring device, and a grounding resistance measuring method.

Background Art

[0002] Patent Document 1 discloses a cord winder used for measuring grounding resistance and a method for measuring grounding resistance using the cord winder.

[0003] When measuring the grounding resistance, the measurer drives a first auxiliary grounding rod into the ground at a location a certain distance away from the location where the conductor to be measured, which is the measurement target, is buried. Further, the measurer drives a second auxiliary grounding rod into the ground at a location a certain distance away from the location where the first auxiliary grounding rod is driven.

[0004] Then, the measurer connects the conductor to be measured and the grounding resistance meter using a measurement cord. Further, the measurer connects the first auxiliary grounding rod and the second auxiliary grounding rod to the grounding resistance meter using the measurement cord of the cord winder, and measures the grounding resistance with the grounding resistance meter.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In such a method for measuring grounding resistance, it is necessary to drive the first auxiliary grounding rod and the second auxiliary grounding rod into the ground.

[0007] For this reason, when the location where each auxiliary grounding rod is to be driven is formed of, for example, concrete, there is a problem that the measurer cannot drive the auxiliary grounding rod and the measurement cannot be performed.

[0008] The present invention has been made in view of the above problems, and an object thereof is to enable measurement even in a place where an auxiliary grounding rod cannot be driven in.

Means for Solving the Problems

[0009] The grounding electrode according to an aspect of the present invention includes a plate-like member, a holding body that is arranged along one surface of the plate-like member and can hold a liquid, and a metal grounding grid that is arranged on top of the holding body.

Effects of the Invention

[0010] In a certain aspect of the present invention, when performing measurement using the grounding electrode, the measurer grounds the metal grounding grid provided on the plate-like member to the ground surface. Then, the measurer supplies a liquid such as water to the grounding electrode. Then, the supplied liquid is held by the holding body. Further, the ground surface in contact with the grounding grid becomes wet with the supplied liquid, and the liquid penetrates into the ground surface. As a result, the contact resistance between the grounding grid and the ground surface is reduced.

[0011] Therefore, even in a place where an auxiliary grounding rod cannot be driven in, the grounding grid can be grounded to the ground surface penetrated by the liquid.

[0012] As a result, for example, the measurer can measure the grounding resistance. The grounding electrode includes a holding body between the plate-like member and the grounding grid, and the liquid is held in the holding body. Therefore, since the wet state of the ground surface can be maintained by the liquid held in the holding body, compared with the case where the ground surface dries out in a short time because it is composed only of the grounding grid, the change in the grounding resistance can be suppressed, and stable measurement of the grounding resistance becomes possible.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0015] Figure 1 is a perspective view showing a portable ground electrode 12 provided with a ground electrode 10 according to an embodiment of the present invention. Figure 2 is a perspective view showing a state in which the ground electrode 10 provided on the portable ground electrode 12 is deployed.

[0016] As shown in FIGS. 1 and 2, the portable ground electrode 12 includes a winder 22 that retractably winds a cable 20, and a ground electrode 10 provided on the winder 22. The ground electrode 10 of the portable ground electrode 12 is used, for example, as an auxiliary electrode when measuring the ground resistance with a ground resistance meter 514 (see FIG. 5). Examples of the method for measuring the ground resistance include the three-electrode method.

[0017] In this embodiment, the case where the ground electrode 10 is used in a state of being attached to the winder 22 will be described as an example, but the usage method of the ground electrode 10 is not limited to this. The ground electrode 10 may be removed from the winder 22 and used alone. Further, the ground electrode 10 may be used in combination with the cable 20 without using the winder 22.

[0018] (Winder) The winder 22 includes a frame 26 and a drum 28 rotatably supported on one side of the frame 26.

[0019] (Frame) Frame 26 is provided with legs 30. The legs 30 extend from the frame 26 toward the lower part of the drum 28. The portable grounding electrode 12 can maintain an upright state by grounding the legs 30 to the ground plane G.

[0020] A handle 32 is formed on the frame 26. The handle 32 is disposed above the portable grounding electrode 12 in the upright state. The handle 32 includes a pair of columns 32A extending upward and a gripping portion 32B connecting the ends of both columns 32A. Thereby, the measurer can carry the portable grounding electrode 12 by gripping the gripping portion 32B with a hand inserted between both columns 32A.

[0021] The frame 26 is provided with a grounding rod attachment portion 36. A grounding rod 38 is detachably attached to the grounding rod attachment portion 36. Further, the frame 26 is provided with a cylindrical support portion (not shown) for rotatably supporting the drum 28.

[0022] (Drum) The drum 28 has a cylindrical body portion (not shown) rotatably supported by the frame 26 and a flange portion 42 extending outward in the circumferential direction from the end of the body portion.

[0023] Specifically, a support portion (not shown) provided on the frame 26 is inserted into the body portion (not shown) of the drum 28. The body portion (not shown) of the drum 28 is prevented from detaching from the frame 26 by a detachment prevention structure provided on the support portion (not shown) of the frame 26. The detachment prevention structure is, for example, a structure in which a claw provided at the end of the support portion (not shown) engages with the body portion (not shown) of the drum 28.

[0024] The drum 28 can wind and hold the cable 20 electrically connected to the grounding electrode 10 around the drum 28 by rotating the drum 28. The drum 28 can pull out the cable 20 wound around the drum 28 by rotating the drum 28 in the reverse direction.

[0025] (Cable) The cable 20 wound around the drum 28 is composed of a test lead in which copper wires are coated with an insulator. At one end of the cable 20, a crocodile clip 50 that can be electrically connected to and disconnected from the grounding electrode 10 is provided. At the other end of the cable 20, a banana terminal 52 that is removably connected to the terminal of a grounding resistance meter 514 (see FIG. 5) is provided. When measuring the grounding resistance using the grounding rod 38, the crocodile clip 50 is connected to the grounding rod 38.

[0026] One end of the cable 20 provided with the crocodile clip 50 is held by the flange portion 42 of the drum 28 while being hung on a hook 54 provided on the flange portion 42 of the drum 28.

[0027] (Grounding Electrode) Next, the grounding electrode 10 will be specifically described with reference to FIGS. 3 and 4. FIG. 3 is a perspective view showing the outer surface of the unfolded grounding electrode 10. FIG. 4 is a perspective view showing the inner surface of the unfolded grounding electrode 10.

[0028] As shown in FIGS. 3 and 4, the grounding electrode 10 includes a plate-like member 60, a holding body 62 (see FIG. 4) that is arranged along one surface 60A (see FIG. 4) of the plate-like member 60 and can hold a liquid, and a metal grounding grid 64 (see FIG. 4) that is arranged on top of the holding body 62.

[0029] (Plate-Like Member) The plate-like member 60 is composed of a first plate-like member 72 and a second plate-like member 74 that are connected via a plate-like hinge 70. On one surface 60A of the plate-like member 60 composed of the first plate-like member 72 and the second plate-like member 74, a flange 60B for positioning the holding body 62 and the grounding grid 64 is formed along the edge. Thereby, the first plate-like member 72 and the second plate-like member 74 have a predetermined thickness.

[0030] The first plate-shaped member 72 is pivotally supported by an extension portion 71 (see FIG. 1) extending from the inside of the first-stage portion 70A formed on one side edge of the hinge 70. The second plate-shaped member 74 is pivotally supported by an extension portion 71 (see FIG. 3) extending from the inside of the second-stage portion 70B formed on the other side edge of the hinge 70. Thereby, the hinge 70 enables the folding of the first plate-shaped member 72 and the second plate-shaped member 74 having a thickness.

[0031] The plate-shaped member 60 can form a folded state 80 (see FIG. 1) in which the first plate-shaped member 72 and the second plate-shaped member 74 overlap with each other with the hinge 70 as the center, with the surface 60A on which the holding body 62 and the grounding grid 64 are arranged facing inward. Further, the plate-shaped member 60 can form an unfolded state 82 (see FIGS. 2 to 4) in which the first plate-shaped member 72 and the second plate-shaped member 74 are unfolded with the hinge 70 as the center so that the grounding grid 64 is exposed.

[0032] The first plate-shaped member 72 and the second plate-shaped member 74 are formed in the same shape. The grounding electrode 10 suppresses the exposure of the grounding grid 64 when in the folded state 80 (see FIG. 1) where the first plate-shaped member 72 and the second plate-shaped member 74 overlap.

[0033] Further, the plate-shaped member 60 becomes rectangular in the unfolded state 82, and the grounding grid 64 folded inside is unfolded and exposed in a rectangular shape (see FIG. 4). Therefore, compared with the case where the plate-shaped member 60 is composed only of the first plate-shaped member 72 having the grounding grid 64, the area of the grounding grid 64 can be increased, and the contact area with the grounding surface G (see FIG. 5) with which the grounding grid 64 is in contact can be increased.

[0034] In the present embodiment, the case where the plate-shaped member 60 is composed of the first plate-shaped member 72 and the second plate-shaped member 74 connected via the hinge 70 will be described as an example, but the plate-shaped member 60 is not limited to this configuration. For example, in the present embodiment, the plate-shaped member 60 may be composed of three or more plate-shaped members connected by the hinge 70. In a structure in which the plate-shaped member 60 is composed of three or more plate-shaped members, it is possible to further increase the area of the grounding grid 64.

[0035] The plate-like member 60 is provided with a holding structure 90 for holding the folded state 80.

[0036] Specifically, the holding structure 90 is composed of a magnet 92 provided at the free end of the second plate-like member 74 and a cylindrical body 94 made of a ferromagnetic material provided at the free end of the first plate-like member 72. In the folded state 80, the magnet 92 faces the cylindrical body 94 and magnetically adheres to the cylindrical body 94. Thereby, the plate-like member 60 is held in the folded state 80.

[0037] The plate-like member 60 has a through hole 100 (see FIG. 3) that penetrates from one surface 60A where the holding body 62 and the grounding grid 64 are arranged to the other surface 60C. Specifically, a circular through hole 100 is formed in the central portion of the first plate-like member 72 formed in a rectangular shape.

[0038] Also, in the central portion of the second plate-like member 74, a rib 150 (see FIG. 3) made of a convex strip is formed in a rectangular shape. A plurality of horizontally long rectangular openings 152 (see FIG. 3) are formed inside the rib 150. Each opening 152 penetrates the second plate-like member 74. Each opening 152 constitutes another through hole that penetrates from one surface 60A where the holding body 62 and the grounding grid 64 are arranged to the other surface 60C.

[0039] The first plate-like member 72 in the plate-like member 60 has a cylindrical portion 102 (see FIG. 3) that is cylindrical and communicates with the through hole 100 and is arranged inside the central hole 101 of the drum 28.

[0040] The central hole 101 of the drum 28 is formed in the inner region of the body portion (not shown) of the drum 28. As described above, a cylindrical support portion (not shown) provided on the frame 26 is inserted into the inner region of the body portion (not shown) of the drum 28. The cylindrical portion 102 (see FIG. 3) of the first plate-like member 72 is inserted into the support portion (not shown) of the frame 26. Thereby, the cylindrical portion 102 (see FIG. 3) of the first plate-like member 72 is arranged inside the central hole 101 of the drum 28.

[0041] The cylindrical portion 102 extends from the opening edge of the through-hole 100 of the first plate-shaped member 72. At the tip of the cylindrical portion 102, flexible pieces 106 formed between a pair of slits 104 are provided at two locations. At the tip of each flexible piece 106, an engaging claw 108 protruding laterally is formed.

[0042] The cylindrical portion 102 has a size that can be inserted into a support portion (not shown) of the frame 26. When the cylindrical portion 102 is inserted into the support portion (not shown) of the frame 26, the engaging claw 108 of the flexible piece 106 engages with the end of the support portion (not shown) of the frame 26. Thereby, the cylindrical portion 102 is attached to the drum 28.

[0043] At the end of the cylindrical portion 102, there is provided a diameter-expanded portion 44 (see FIG. 1) that protrudes from the drum 28 and has an inner diameter dimension 43 that increases as it extends in the protruding direction. The cylindrical portion 102 and the diameter-expanded portion 44 are separate members.

[0044] Specifically, at the end of the cylindrical portion 102, a pair of protruding pieces 105 (see FIG. 3) protruding inward are formed. At the end of the diameter-expanded portion 44, a screw portion (not shown) that is cylindrical and has a male screw formed on its outer peripheral portion is provided. The diameter-expanded portion 44 is attached to the cylindrical portion 102 by screwing the screw portion into the end of the cylindrical portion 102 having the protruding pieces 105.

[0045] The diameter-expanded portion 44 protrudes outward beyond the flange portion 42 of the drum 28. The diameter-expanded portion 44 communicates with the cylindrical portion 102.

[0046] (Holder) As shown in FIG. 4, the holder 62 is formed in a thin plate shape that is substantially the same shape as the plate-shaped member 60 composed of the first plate-shaped member 72 and the second plate-shaped member 74. The holder 62 is provided across the first plate-shaped member 72 to the second plate-shaped member 74. The holder 62 has water retention and holds the liquid in a releasable manner. The holder 62 is composed of, for example, a sponge that absorbs and holds the liquid and can release the held liquid little by little.

[0047] The liquid is composed of, for example, water. The liquid may be other than water as long as it can reduce the contact resistance between the grounding grid 64 and the ground surface G (see FIG. 5).

[0048] In this embodiment, the case where the holding body 62 is made of sponge is taken as an example for explanation, but the holding body 62 is not limited to sponge. The holding body 62 may be any thing that can hold the liquid.

[0049] (Grounding grid) The grounding grid 64 is formed in the same shape as the holding body 62. The grounding grid 64 has a size that can be arranged from the first plate-like member 72 to the second plate-like member 74. In FIG. 4, the grounding grid 64 is shown in a state where a part of it is omitted.

[0050] The grounding grid 64 is formed by, for example, copper wires which are conductors being knitted three-dimensionally. The mesh size of the grounding grid 64 is, for example, 1 mm or less. The grounding grid 64 allows the liquid discharged from the holding body 62 to permeate slowly.

[0051] Metal bolts 110 are inserted into the corners of the grounding grid 64 on the side of the first plate-like member 72. Each bolt 110 is electrically connected to the grounding grid 64. Each bolt 110 passes through the holding body 62. Also, the screw portion of each bolt 110 is screwed into a screw hole (not shown) provided in the first plate-like member 72.

[0052] The tip of the screw portion of each bolt 110 protrudes from the other surface 60C of the plate-like member 60 (see FIG. 3). The tip of the bolt 110 protruding from the other surface 60C of the plate-like member 60 constitutes a connection portion 112 to which the alligator clip 50 is electrically connected.

[0053] At the corner on the side of the second plate-shaped member 74 in the grounding grid 64, a pin 120 is inserted. Each pin 120 passes through the holder 62. Further, each pin 120 is movably supported in a long hole 122 (see FIG. 3) formed in the second plate-shaped member 74. The long hole 122 extends in the length direction of the plate-shaped member 60. Thereby, the holder 62 and the grounding grid 64 are allowed to move in the length direction of the plate-shaped member 60 that occurs when forming the deployed state 82 or the folded state 80 by the long hole 122.

[0054] (Usage example) FIG. 5 is an explanatory diagram showing a usage state of the grounding electrode 10 (10A, 10B) according to the embodiment. A usage example of using the grounding electrode 10 (10A, 10B) of the portable grounding electrode 12 (12A, 12B) as an auxiliary electrode will be described with reference to FIG. 5.

[0055] In FIG. 5, a first portable grounding electrode 12A and a second portable grounding electrode 12B are shown as the portable grounding electrode 12. In FIG. 5, the reference numerals indicating the components of the first portable grounding electrode 12A are attached with "A" in order to make it easy to understand that they are the components of the first portable grounding electrode 12A. Further, the reference numerals indicating the components of the second portable grounding electrode 12B are attached with "B" in order to make it easy to understand that they are the components of the second portable grounding electrode 12B.

[0056] When measuring the grounding resistance, a grounding resistance measuring device 500 is used.

[0057] The grounding resistance measuring device 500 includes the grounding electrode 10 (10A, 10B) described above. Further, the grounding resistance measuring device 500 is electrically connected to the grounding grid 64 (64A, 64B) of the grounding electrode 10 (10A, 10B) and is also electrically connected to a measurement object 512 buried in the ground 510, and includes a grounding resistance meter 514 that measures the grounding resistance of the measurement object 512.

[0058] By using this grounding resistance measuring device 500, a grounding resistance measuring method for measuring the grounding resistance of the measurement object 512 buried in the ground 510 using the grounding electrode 10 (10A, 10B) is realized.

[0059] In FIG. 5, a measurement object 512 for measuring the ground resistance is buried in the ground 510 for measuring the ground resistance. The ground resistance indicates the contact resistance between the measurement object 512 and the earth.

[0060] The measurement object 512 constitutes a ground electrode [E]. The banana terminal 522 of the electric wire 520 connected to the measurement object 512 is connected to the E terminal 524 of the ground resistance meter 514.

[0061] When measuring the ground resistance with the ground resistance meter 514, the user prepares a first portable ground electrode 12A and a second portable ground electrode 12B.

[0062] The user transports the first portable ground electrode 12A to a location, for example, more than 5 m and less than 10 m away from the measurement object 512.

[0063] Also, the measurer unfolds the first plate-like member 72 (see FIG. 2) and the second plate-like member 74 of the ground electrode 10A to form an unfolded state 82. Then, the ground grid 64A arranged along the first plate-like member 72 and the second plate-like member 74 is exposed in the unfolded state.

[0064] Then, the measurer tilts the first portable ground electrode 12A so that the drum 28A is on the upper side. Then, the unfolded ground grid 64A contacts the ground surface G. Note that the measurer may remove the ground electrode 10A from the drum 28A of the first portable ground electrode 12A and arrange the ground electrode 10A on the ground surface G so that the ground grid 64A of the ground electrode 10A contacts the ground surface G.

[0065] Next, the measurer pours a liquid such as water into the enlarged diameter portion 44A of the first portable ground electrode 12A. Then, the liquid is supplied to the ground plane G through the cylindrical portion 102 (see FIG. 3), the through hole 100 of the plate-like member 60, the holding body 62A provided on the plate-like member 60, and the ground grid 64A, and penetrates the ground plane G. Thereby, the contact resistance between the ground grid 64A and the ground plane G is reduced. When the ground is covered with concrete, it is desirable for the measurer to supply the liquid until the liquid that has penetrated the concrete reaches the ground covered with concrete. The ground grid 64A of the first portable ground electrode 12A constitutes a potential electrode [S] as a measurement auxiliary electrode.

[0066] Here, the measurer may sprinkle the liquid around the ground electrode 10A to penetrate the liquid into the ground plane G and hold the liquid by the holding body 62A.

[0067] Then, the user electrically connects the alligator clip 50 (see FIG. 2) provided at one end of the cable 20A of the first portable ground electrode 12A to the connection portion 112 (see FIG. 3) of the ground electrode 10A. Also, the measurer pulls out the cable 20A from the drum 28A of the first portable ground electrode 12A and connects the banana terminal 52A provided at the other end of the cable 20A to the first connection portion 526 of the ground resistance meter 514.

[0068] Also, the user transports the second portable ground electrode 12B to a location, for example, more than 5 m and less than 10 m away from the location where the first portable ground electrode 12A is arranged.

[0069] Also, the measurer expands the first plate-like member 72 (see FIG. 2) and the second plate-like member 74 of the ground electrode 10B to form an expanded state 82. Then, the ground grid 64B arranged along the first plate-like member 72 and the second plate-like member 74 is exposed in the expanded state.

[0070] Then, the measurer tilts the second portable grounding electrode 12B so that the drum 28B is on the upper side. Then, the deployed grounding grid 64B contacts the grounding surface G. Note that the measurer may remove the grounding electrode 10B from the drum 28B of the second portable grounding electrode 12B and arrange the grounding electrode 10B on the grounding surface G so that the grounding grid 64B of the grounding electrode 10B contacts the grounding surface G.

[0071] Thereby, the grounding grid 14B of the grounding electrode 10B of the second portable grounding electrode 12B is grounded to the grounding surface G at a position on a straight line passing through the position where the measurement object 512 is buried and the position where the grounding grid 64A of the first portable grounding electrode 12A is grounded to the grounding surface G.

[0072] Next, the measurer pours a liquid such as water into the diameter-expanded portion 44B of the second portable grounding electrode 12B. Then, the liquid is supplied to the grounding surface G through the cylindrical portion 102 (see FIG. 3), the through-hole 100 of the plate-like member 60, the holding body 62B provided on the plate-like member 60, and the grounding grid 64B, and penetrates the grounding surface G. Thereby, the contact resistance between the grounding grid 64B and the grounding surface G is reduced. When the ground is covered with concrete, it is desirable for the measurer to supply the liquid until the liquid that has penetrated the concrete reaches the ground covered with concrete. The grounding grid 64B of this second portable grounding electrode 12B constitutes the current electrode [H] as a measurement auxiliary electrode.

[0073] Here, the measurer may sprinkle the liquid around the grounding electrode 10B to penetrate the liquid into the grounding surface G and hold the liquid by the holding body 62.

[0074] Then, the user electrically connects the alligator clip 50 (see FIG. 2) provided at one end of the cable 20B of the second portable grounding electrode 12B to the connection portion 112 (see FIG. 3) of the grounding electrode 10B. Also, the measurer pulls out the cable 20B from the drum 28B of the second portable grounding electrode 12B and connects the banana terminal 52B provided at the other end of the cable 20B to the second connection portion 528 of the grounding resistance meter 514.

[0075] In this state, the user operates the ground resistance meter 514, and the ground resistance meter 514 causes a current to flow, for example, between the ground grid 64B (current electrode [H]) of the second portable ground electrode 12B and the measurement target 512 (ground electrode [E]). Then, the user measures the voltage between the ground grid 64A (potential electrode [S]) of the first portable ground electrode 12A and the measurement target 512 (ground electrode [E]) with the ground resistance meter 514 to measure the ground resistance.

[0076] (Function and Effect) Next, the function and effect of this embodiment will be described.

[0077] The ground electrode 10 in this embodiment includes a plate-like member 60, a holding body 62 that is arranged along one surface 60A of the plate-like member 60 and can hold a liquid, and a metal ground grid 64 that is arranged on top of the holding body 62.

[0078] In this configuration, when using the ground electrode 10, the measurer grounds the metal ground grid 64 provided on the plate-like member 60 to the ground surface G. Then, the measurer supplies a liquid such as water to the ground electrode 10. Then, the supplied liquid is held by the holding body 62.

[0079] Also, the liquid discharged from the holding body 62 passes through the meshes of the ground grid 64 and reaches the ground surface G. Then, the ground surface G in contact with the ground grid 64 becomes wet with the liquid, and the liquid penetrates into the ground surface G. As a result, the contact resistance between the ground grid 64 and the ground surface G is reduced.

[0080] Therefore, even when the ground surface G is made of, for example, concrete where a ground rod 38 cannot be driven in, the measurer can reduce the contact resistance between the ground surface G and the ground grid 64 by allowing the liquid to penetrate into the ground surface G, and it becomes possible to measure the ground resistance.

[0081] And the ground electrode 10 includes a holding body 62 between the plate-like member 60 and the ground grid 64, and the holding body 62 holds the liquid. Also, the holding body 62 has a water retention capacity and discharges the held liquid little by little.

[0082] As a result, the ground electrode 10 can keep the ground plane G in a wetted state by the liquid held by the holding member 62. Therefore, the ground electrode 10 according to the present embodiment can suppress changes in the ground resistance during measurement and enable stable measurement of the ground resistance, as compared with the case where the ground plane G dries out in a short time by adopting a structure without the holding member 62.

[0083] In addition, the ground resistance measuring device 500 of the present embodiment includes a ground electrode 10 and a ground resistance meter 514 that is electrically connected to the ground grid 64 of the ground electrode 10 and electrically connected to a measurement target 512 buried in the ground 510 to measure the ground resistance of the measurement target 512.

[0084] And the ground resistance measuring method of the present embodiment measures the ground resistance of the measurement target 512 buried in the ground 510 using the ground electrode 10.

[0085] Also in this configuration, similar to the above, even in a place formed of concrete where the ground rod 38 cannot be driven, by infiltrating the liquid into the ground plane G, the contact resistance between the ground plane G and the ground grid 64 can be reduced, so that the ground resistance can be measured.

[0086] In addition, since the ground plane G can be kept in a wetted state by the liquid held by the holding member 62, similar to the above, changes in the ground resistance during measurement can be suppressed, and stable measurement of the ground resistance becomes possible.

[0087] In addition, in the present embodiment, the plate-like member 60 includes a first plate-like member 72 and a second plate-like member 74 connected via a hinge 70.

[0088] In this configuration, by expanding the first plate-like member 72 and the second plate-like member 74 around the hinge 70, the area of the ground grid 64 arranged along the plate-like member 60 can be increased compared to the case where the plate-like member 60 is composed of only the first plate-like member 72. As a result, the contact resistance between the ground grid 64 and the ground plane G can be reduced.

[0089] In addition, in the present embodiment, the plate-shaped member 60 can form a folded state 80 in which the first plate-shaped member 72 and the second plate-shaped member 74 overlap with the grounding grid 64 on the inside, with the hinge 70 as the center. Further, the plate-shaped member 60 can form an unfolded state 82 in which the first plate-shaped member 72 and the second plate-shaped member 74 are unfolded with the hinge 70 as the center so that the grounding grid 64 is exposed. The plate-shaped member 60 includes a holding structure 90 for holding the folded state 80.

[0090] In this configuration, the grounding electrode 10 can change the plate-shaped member 60 in the unfolded state 82 to the folded state 80 during use. Therefore, the grounding electrode 10 can be made compact during storage while maintaining the area of the grounding grid 64 in the use state.

[0091] Further, the grounding electrode 10 can sandwich the grounding grid 64 with the first plate-shaped member 72 and the second plate-shaped member 74 with the grounding grid 64 on the inside in the folded state 80, and can hold the folded state 80 by the holding structure 90. Therefore, the grounding electrode 10 can be stored in a state where dirt and the like are hidden as compared with the case where the grounding grid 64 in a dirty and wet state remains exposed during use.

[0092] In addition, in the present embodiment, the plate-shaped member 60 has a through hole 100 (opening 152) penetrating from one surface 60A to the other surface 60C.

[0093] In this configuration, the grounding electrode 10 can supply a liquid to the holding body 62 through the through hole 100 from the other surface 60C side of the plate-shaped member 60 in a state where the grounding grid 64 provided on the one surface 60A side of the plate-shaped member 60 is in contact with the ground plane G.

[0094] Therefore, even when the ground plane G is dry, the ground electrode 10 can supply liquid to the ground plane G through the liquid holding body 62 and the ground grid 64 in a measurement state where the ground grid 64 is grounded to the ground plane G. For this reason, the convenience of the ground electrode 10 is improved as compared with the case where the ground grid 64 has to be wound when wetting the ground plane G.

[0095] In this embodiment, a through hole 100 is formed in the central portion of the first plate-like member 72. For this reason, the ground electrode 10 of this embodiment can uniformly supply the liquid supplied from the through hole 100 over a wide range of the liquid holding body 62 and the ground grid 64 provided on the first plate-like member 72.

[0096] Also, in this embodiment, a plurality of openings 152 are formed in the central portion of the second plate-like member 74. For this reason, the ground electrode 10 of this embodiment can uniformly supply the liquid supplied from each opening 152 over a wide range of the liquid holding body 62 and the ground grid 64 provided on the second plate-like member 74.

[0097] And in this embodiment, on the second plate-like member 74, ribs 150 formed of ridges are formed so as to surround the openings 152. For this reason, in this embodiment, when supplying liquid from the openings 152, it is possible to suppress the outflow of the liquid to the outside of the ribs 150.

[0098] Further, the ground electrode 10 of this embodiment further includes a drum 28 that winds and holds a cable 20 that can be electrically connected to the ground grid 64. The plate-like member 60 is cylindrical and communicates with the through hole 100 and has a cylindrical portion 102 disposed in the central hole 101 of the drum 28.

[0099] In this configuration, the ground electrode 10 can ground the ground grid 64 at a location away from the ground resistance meter 514 by using the cable 20 wound around the drum 28.

[0100] Further, when the drum 28 tilts at the grounding location, the grounding grid 64 contacts the grounding surface G for the grounding electrode 10. Therefore, the measurer can easily ground the grounding grid 64 to the grounding surface G.

[0101] In the grounded state, the load of the drum 28 and the cable 20 held by the drum 28 is applied to the grounding grid 64. Thereby, the grounding electrode 10 can reduce the contact resistance between the grounding grid 64 and the grounding surface G as compared with the case where only the grounding grid 64 is disposed on the grounding surface G.

[0102] And, since the liquid can be supplied to the holder 62 of the plate-like member 60 and the grounding grid 64 through the cylindrical portion 102 disposed in the central hole 101 of the tilted drum 28, the convenience is improved.

[0103] In addition, the grounding electrode 10 of the present embodiment is integrated with the drum 28 by disposing the cylindrical portion 102 of the plate-like member 60 having the grounding grid 64 in the central hole 101 of the drum 28. Therefore, the grounding electrode 10 can save the trouble of tidying up as compared with the case where it is separated from the drum 28.

[0104] Furthermore, since the cylindrical portion 102 of the plate-like member 60 is disposed in the central hole 101 of the drum 28, the plate-like member 60 can be set on the drum 28 without hindering the rotation of the drum 28 for the grounding electrode 10 of the present embodiment.

[0105] In addition, in the present embodiment, a diameter-expanded portion 44 that protrudes from the drum 28 and has an inner diameter dimension 43 that increases as it goes in the protruding direction is provided at the end of the cylindrical portion 102.

[0106] In this configuration, when supplying the liquid, since the liquid can be supplied to the grounding electrode 10 through the diameter-expanded portion 44 whose inner diameter dimension 43 increases as it goes in the direction protruding from the drum 28, it is possible to suppress the spillage of the liquid.

[0107] The embodiments of the present invention have been described above. However, the above embodiments merely show some application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Explanation of Reference Numerals

[0108] 10 Ground electrode 20 Cable 28 Drum 40 Shaft portion 43 Inner diameter dimension 44 Diameter-expanded portion 60 Plate-like member 60A One surface 60C The other surface 62 Holder 64 Grounding grid 70 Hinge 72 First plate-like member 74 Second plate-like member 80 Folded state 82 Expanded state 90 Holding structure 100 Through hole 102 Cylindrical portion 500 Ground resistance measuring device 510 Underground 512 Measurement target 514 Ground resistance meter G Ground surface

Claims

1. A plate-shaped member, a holding body arranged along one surface of the plate-shaped member and capable of holding a liquid, a grounding grid made of metal and arranged on top of the holding body, and a grounding electrode comprising the same.

2. The grounding electrode according to Claim 1, wherein the plate-shaped member comprises a first plate-shaped member and a second plate-shaped member connected via a hinge. Grounding electrode.

3. The grounding electrode according to Claim 2, wherein the plate-shaped member can form a folded state in which the first plate-shaped member and the second plate-shaped member are folded around the hinge so that the grounding grid is inside and they overlap, and an unfolded state in which the first plate-shaped member and the second plate-shaped member are unfolded around the hinge so that the grounding grid is exposed, and the plate-shaped member comprises a holding structure for holding the folded state. Grounding electrode.

4. The grounding electrode according to Claim 1, wherein the plate-shaped member has a through hole penetrating from one surface to the other surface. Grounding electrode.

5. The grounding electrode according to Claim 4, further comprising a drum for winding and holding a cable electrically connectable to the grounding grid, wherein the plate-shaped member has a cylindrical portion communicating with the through hole and arranged inside the central hole of the drum. Grounding electrode.

6. The grounding electrode according to Claim 5, wherein an enlarged diameter portion is provided at an end of the cylindrical portion, which protrudes from the drum and has an inner diameter that increases in the protruding direction. Grounding electrode.

7. The grounding electrode according to any one of Claims 1 to 6, and a grounding resistance meter electrically connected to the grounding grid of the grounding electrode and electrically connected to a measurement object buried in the ground for measuring the grounding resistance of the measurement object. Grounding resistance measuring device comprising the same.

8. A grounding resistance measuring method for measuring the grounding resistance of a measurement object buried in the ground using the grounding electrode according to any one of Claims 1 to 6. Grounding resistance measuring method.

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