JP2004247240A

JP2004247240A - Graph for indicating relationship between increasing rate in equivalent semispherical body radius of ground electrode and decreasing rate in ground resistance

Info

Publication number: JP2004247240A
Application number: JP2003038044A
Authority: JP
Inventors: Masami Fujii; 正視藤井
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-02-17
Filing date: 2003-02-17
Publication date: 2004-09-02

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a graph capable of directly indicating the relationship between an increasing rate in the equivalent semispherical body radius of a ground electrode and a decreasing rate in ground resistance in the ground construction of an induction prevention measure in facilities for electric power and communication. <P>SOLUTION: A graduation of 1r-100r is made in one of the abscissa and ordinate of logarithmic coordinates, a graduation of 0.01-1.0 is made in the other as the decreasing rate in the ground resistance, and the relationship between the increasing rate in the equivalent semispherical body radius of the ground electrode and the decreasing rate of the ground resistance is indicated by a straight line for connecting the coordinates point of a value 100 of the abscissa and a value 0.01 of the ordinate to that of a value 1r of the abscissa and a value 1.0 of the ordinate. Additionally, a value that is 1.25 times larger than 1r-100r is graduated in one of the abscissa and ordinate of logarithmic coordinates, a value that is 0.8 times larger than 0.01-1.0 is graduated in the other as the decreasing rate in the ground resistance, and the relationship is indicated by a straight line for connecting the coordinates point of a value 80r of the abscissa and a value 0.008 of the ordinate to that of a value 0.8r of the abscissa and a value 1.25 of the ordinate. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係表示グラフ、特に、対数座標を用いた接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係表示グラフに関するものである。
【０００２】
【従来の技術】
接地抵抗の電圧波及間隔等を計算した整数倍（自然数）の対数グラフは既知である（例えば特許文献１）。
【０００３】
【特許文献１】
特開２００１−１４８２７４号公報（第４，６，９頁、図３，図５，図８，図１１）。
【０００４】
従来、電力、通信用施設の誘導防止策用接地工事等において、着工に先立って接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係を推定する必要がある。
【０００５】
【発明が解決しようとする課題】
然しながら上記の関係を直続できるグラフは得られていない。
【０００６】
本発明は上記のグラフを得るようにしたものである。
【０００７】
【課題を解決するための手段】
本発明の接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係表示グラフは、対数座標のグラフの横軸と縦軸の何れか一方に１ｒ〜１００ｒ（ここでｒは等価半球体の半径）を目盛り、何れか他方に接地抵抗の低減率として０．０１〜１．０を目盛り、横軸の値１００と縦軸の値０．０１との座標点と、横軸の値１ｒと縦軸の値１．０との座標点とを結んだ直線によって接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係を示すようにしたことを特徴とする。
【０００８】
また、本発明の接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係表示グラフは、対数座標のグラフの横軸と縦軸の何れか一方に１ｒ〜１００ｒ（ここでｒは等価半球体の半径である）の１．２５倍の値を目盛り、何れか他方に０．０１〜１．０の０．８倍の値を接地抵抗の低減率として目盛り、横軸の値８０ｒと縦軸の値０．００８との座標点と、横軸の値０．８ｒと縦軸の値１．２５との座標点とを結んだ直線によって接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係を示すようにしたことを特徴とする。
【０００９】
【発明の実施の形態】
以下図面によって本発明の実施例を説明する。
【００１０】
図１の半径ｒの半球体（椀形状）接地１の中心から接地極の等価半径ｒ_１迄に含まれる地中接地抵抗をＲ_１、大地３の抵抗率をρとすると、接地抵抗Ｒ_１は次のように計算される。
【００１１】
Ｒ_１＝ρ／２π（（１／ｒ）−（１／ｒ_１））又、半径ｒの半球体状接地電極の接地抵抗Ｒは、Ｒ＝ρ／（２πｒ）となる。
【００１２】
また、図２の深埋設接地電極２の場合、その等価半径ｒは次式で求められる。
【００１３】
ｒ＝Ｌ／（Ｌｎ（（４Ｌ／ｄ）−１））
【００１４】
ここでＬは接地電極の埋設長さ（深さ）、ｄは接地電極断面の等価半径である。
【００１５】
この接地電極に接地電流が流れた時、埋設した地中の大地抵抗率ρが一様で接地極の形状が棒状の場合、接地抵抗Ｒ（Ω）は次のように計算できる。
【００１６】
Ｒ＝（ρ／（２πＬ））・（Ｌｎ（４Ｌ／ｄ）−１）
【００１７】
この接地電極に大きな接地電流が通電した場合、即ち、大きな接地電圧が印加された場合、土中放電の作用もありその接地抵抗Ｒ’（Ω）はＲの８０％程度に低減する。
【００１８】
Ｒ’＝Ｒ×０．８
【００１９】
また、このときの等価半径ｒも次のように大きくなったと見做せる。
【００２０】
ｒ’＝ｒ／０．８＝１．２５・ｒ
【００２１】
図３はこの関係を普通座標のグラフで示したものである。
【００２２】
本発明においては普通座標のグラフに代えて対数座標のグラフを用いると上記の関係を直読できることを見出した。
【００２３】
即ち、本発明においては、図４に示すように対数座標のグラフの横軸と縦軸の何れか一方例えば横軸に１ｒ〜１００ｒ（ここでｒは等価半球体の半径）を目盛り、何れか他方例えば縦軸に接地抵抗の低減率として０．０１〜１．０を目盛り、横軸の値１００と縦軸の値０．０１との座標点と、横軸の値１ｒと縦軸の値１．０との座標点とを結んだ直線によって接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係を示すようにする。
【００２４】
また、本発明においては、同じく対数座標のグラフの横軸と縦軸の何れか一方例えば横軸に１ｒ〜１００ｒ（ここでｒは等価半球体の半径である）の１．２５倍の値を目盛り、何れか他方例えば縦軸に０．０１〜１．０の０．８倍の値を接地抵抗の低減率として目盛り、横軸の値８０ｒと縦軸の値０．００８との座標点と、横軸の値０．８ｒと縦軸の値１．２５との座標点とを結んだ直線によって接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係を示すようにする。
【００２５】
【発明の効果】
上記のように本発明の図４に示すグラフを用いると接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係表示グラフを極めて容易に誤差なく判定できるようになる大きな利益がある。
【図面の簡単な説明】
【図１】椀形接地電極の概念図である。
【図２】深埋設接地電極の概念図である。
【図３】等価半球体からの距離と地表面の電位の関係を示すグラフである。
【図４】本発明の接地電極の等価半球体半径の増加率と接地抵抗の低減率の関係表示グラフである。
【符号の説明】
１接地
２深埋設接地電極
３大地[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a graph showing the relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance, and in particular, the relation display of the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance using logarithmic coordinates. It is about a graph.
[0002]
[Prior art]
2. Description of the Related Art A logarithmic graph of an integral multiple (natural number) of calculating a voltage spreading interval of a ground resistance and the like is known (for example, Patent Document 1).
[0003]
[Patent Document 1]
JP 2001-148274 A (pages 4, 6, 9; FIGS. 3, 5, 8, and 11).
[0004]
2. Description of the Related Art Conventionally, in grounding work for preventing electric power and communication facilities from guiding, it is necessary to estimate the relationship between the rate of increase in the equivalent hemispherical radius of the ground electrode and the rate of reduction in grounding resistance before grounding.
[0005]
[Problems to be solved by the invention]
However, a graph that can directly continue the above relationship has not been obtained.
[0006]
In the present invention, the above-mentioned graph is obtained.
[0007]
[Means for Solving the Problems]
The graph showing the relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance of the ground electrode according to the present invention is 1r to 100r (where r is the equivalent hemisphere) on either the horizontal axis or the vertical axis of the logarithmic coordinate graph. The radius of the body) as a scale, 0.01 to 1.0 as the reduction rate of the ground resistance on either of the scales, a coordinate point of 100 on the horizontal axis and 0.01 on the vertical axis, and the value on the horizontal axis The relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance is represented by a straight line connecting 1r and the coordinate point of the value 1.0 on the vertical axis.
[0008]
In addition, the graph showing the relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance of the ground electrode according to the present invention is 1r to 100r (where r is one of the horizontal axis and the vertical axis of the logarithmic coordinate graph). A value of 1.25 times the scale of the equivalent hemisphere) is graduated, and a value of 0.8 times of 0.01 to 1.0 is graduated as a reduction ratio of the ground resistance, and the value of the horizontal axis is 80r. And the increase rate of the equivalent hemisphere radius of the ground electrode by a straight line connecting the coordinate point of the vertical axis value 0.008 and the coordinate point of the horizontal axis value 0.8r and the vertical axis value 1.25. The relationship of the reduction rate of the ground resistance is shown.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
Assuming that an underground ground resistance included from the center of the hemispherical (bowl-shaped) ground 1 having a radius r of FIG. 1 to the equivalent radius r _{1 of the} ground pole is R ₁ and a resistivity of the ground 3 is ρ, the ground resistance R ₁ Is calculated as follows:
[0011]
R ₁ = ρ / 2π ((1 / r) − (1 / r ₁ )) Further, the ground resistance R of the hemispherical ground electrode having the radius r is R = ρ / (2πr).
[0012]
In the case of the deeply buried ground electrode 2 in FIG. 2, the equivalent radius r is obtained by the following equation.
[0013]
r = L / (Ln ((4L / d) -1))
[0014]
Here, L is the buried length (depth) of the ground electrode, and d is the equivalent radius of the cross section of the ground electrode.
[0015]
When a ground current flows through this ground electrode, if the ground resistivity ρ in the buried ground is uniform and the shape of the ground electrode is a rod, the ground resistance R (Ω) can be calculated as follows.
[0016]
R = (ρ / (2πL)) · (Ln (4L / d) −1)
[0017]
When a large ground current is applied to the ground electrode, that is, when a large ground voltage is applied, the ground resistance R ′ (Ω) is reduced to about 80% of R due to the action of earth discharge.
[0018]
R ′ = R × 0.8
[0019]
In addition, it can be considered that the equivalent radius r at this time has also increased as follows.
[0020]
r ′ = r / 0.8 = 1.25 · r
[0021]
FIG. 3 shows this relationship in a graph of ordinary coordinates.
[0022]
In the present invention, it has been found that the above relationship can be directly read by using a graph of logarithmic coordinates instead of a graph of ordinary coordinates.
[0023]
That is, in the present invention, as shown in FIG. 4, one of the horizontal axis and the vertical axis of the graph of the logarithmic coordinate is, for example, 1r to 100r (where r is the radius of the equivalent hemisphere) on the horizontal axis. On the other hand, for example, the vertical axis indicates a scale of 0.01 to 1.0 as the reduction rate of the ground resistance, the coordinate point of the horizontal axis value 100 and the vertical axis value 0.01, the horizontal axis value 1r and the vertical axis value The relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance is represented by a straight line connecting the coordinate point of 1.0 and the coordinate point.
[0024]
Further, in the present invention, one of the horizontal axis and the vertical axis of the graph of logarithmic coordinates, for example, the horizontal axis represents a value of 1.25 times 1r to 100r (where r is the radius of the equivalent hemisphere). Scale, one of the other scales, for example, a value of 0.8 times 0.01 to 1.0 on the vertical axis as a reduction rate of the ground resistance, a coordinate point of a value 80r on the horizontal axis and a value 0.008 on the vertical axis. The relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance is represented by a straight line connecting the coordinate point of the value 0.8r on the horizontal axis and the value 1.25 on the vertical axis.
[0025]
【The invention's effect】
As described above, the use of the graph shown in FIG. 4 of the present invention has a great advantage that a graph showing the relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance can be determined very easily without error. .
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a bowl-shaped ground electrode.
FIG. 2 is a conceptual diagram of a deeply buried ground electrode.
FIG. 3 is a graph showing a relationship between a distance from an equivalent hemisphere and a potential on the ground surface.
FIG. 4 is a graph showing the relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance of the ground electrode according to the present invention.
[Explanation of symbols]
1 Ground 2 Deeply buried ground electrode 3 Earth

Claims

1r to 100r (where r is the radius of the equivalent hemisphere) is graduated on either the horizontal axis or the vertical axis of the graph of logarithmic coordinates, and 0.01 to 1.0 is used as the reduction rate of the grounding resistance on one of the other. The equivalent hemisphere radius of the ground electrode by a straight line connecting the coordinate point of the horizontal axis value 100 and the vertical axis value 0.01 and the coordinate point of the horizontal axis value 1r and the vertical axis value 1.0. A graph showing the relationship between the increase rate of the equivalent hemispherical radius of the ground electrode and the reduction rate of the ground resistance, wherein the relation between the increase rate of the ground resistance and the reduction rate of the ground resistance is shown.

One of the horizontal axis and the vertical axis of the graph of logarithmic coordinates is a scale of 1.25 times 1r to 100r (where r is the radius of the equivalent hemisphere), and 0.01 to 1 is plotted on the other side. 0.8 is set as the reduction ratio of the ground resistance, the coordinate point of the horizontal axis value 80r and the vertical axis value 0.008, the horizontal axis value 0.8r and the vertical axis value 1 .25, which indicates the relationship between the increase rate of the equivalent hemisphere radius of the ground electrode and the reduction rate of the ground resistance by a straight line connecting the coordinate points of .25. Is a graph showing the relationship between the resistance and the reduction rate of the grounding resistance.