JP2009216599A - Device and method for measuring earth resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply and accurately measure earth resistance by positioning a movable terminal for fixed resistance of a variable resistor and calculating the earth resistance of a first grounding electrode based on measuring current of each current detector when changing the applied voltage of each power source and the state of each switch. <P>SOLUTION: The earth resistance of the side of a device 1 for measuring the earth resistance, and a concatenated earth resistance 2 as a measuring object composes one serial circuit including the ground. The earth resistance (or its index value) of the side of the device 1 for measuring the earth resistance is specified by using a resistance R<SB>T</SB>for balancing regulation, a first auxiliary earth pole resistance R<SB>K1</SB>, a second auxiliary earth pole resistance R<SB>K2</SB>or the like provided on the device 1 for measuring the earth resistance, meanwhile the earth resistance of the whole serial circuit adding the device 1 for measuring the earth resistance and the concatenated earth resistance 2 is measured. Subsequently, the concatenated earth resistance 2 is calculated by subtracting the earth resistance of the side of the device 1 for measuring the earth resistance from the entire earth resistance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ground resistance measuring device capable of measuring a connected ground resistance.

  Conventionally, when measuring the ground resistance value of a distribution facility, a measuring instrument using a potential drop method is mainly used to maintain and manage the ground resistance value.

  By the way, depending on the geology of the location where the power distribution equipment is installed, it may be difficult to lower the grounding resistance value to the specified value. In many cases, the grounding work is performed by using an articulated grounding method (for example, an aerial joint ground wire). By using the articulated grounding method, the grounding resistance value can be lowered, and the cost can be reduced because a plurality of locations are constructed at once.

  Here, the potential drop method and the multiple grounding system earther will be described.

≪Potential drop method≫
FIG. 2 is a diagram showing a configuration of the potential drop method and a potential distribution curve. The potential drop method is one of the methods for measuring the ground resistance. FIG. 2A shows a configuration for implementing the potential drop method. The current auxiliary pole C is grounded at a predetermined distance from the main ground pole E, which is a measurement target of the ground resistance. In addition, the potential auxiliary pole P is grounded in the vicinity of an intermediate point between the main grounding electrode E and the current auxiliary pole C. At the time of measurement, a constant current I [A] is supplied to the ground by connecting a power source as a constant current generator between ECs. Subsequently, the voltage drop (potential difference) V [V] between the EPs is measured by the potential auxiliary pole P. Then, V / I [Ω] is a ground resistance value.

  FIG. 2B shows a potential distribution curve of each ground electrode used in the potential drop method. In the vicinity of the main grounding electrode E, the potential suddenly increases, the change in potential becomes slow at the intermediate point, the potential increases again in the vicinity of the current auxiliary pole C, and becomes equal to the applied voltage on the current auxiliary pole C. If this phenomenon is explained by current distribution, the change in potential increases because the current density is large near the main ground electrode E and the auxiliary current pole C, but the change in potential also decreases near the middle point because the current density is small.

FIG. 2C shows two types of potential distribution curves. Although the potential distribution curve P ₂ is a horizontal section in the center has occurred, there is no horizontal portion in the potential distribution curve P _1. If you release the current auxiliary electrode C ₂ to a horizontal portion at its center as the potential distribution curve P ₂ is generated, almost no influence of larger current density in the main ground electrode near the E and the current auxiliary electrode C ₂ It can be judged. Therefore, by dividing the potential difference Ex measured from this horizontal portion by the current value at that time, the ground resistance value of E can be obtained. However, the main ground electrode E as potential distribution curve P _1, when a current auxiliary pole C ₁ is too close, because it can not horizontal portion such as the electric potential distribution curve P _2, precise ground resistance Can no longer be sought.

FIG. 3 is a diagram showing a configuration when an attempt is made to measure the combined resistance value of the connected grounding resistance using the voltage drop method. The articulated ground resistance is composed of seven ground resistances R _{1 to} R ₇ . Then, the grounding location of the grounding resistor R ₆ is set as the main grounding electrode E, the current auxiliary electrode C and the potential auxiliary electrode E are provided, and an attempt is made to measure the grounding resistance value. However, since the current from the current auxiliary pole C does not go only to the grounding electrode of R ₆ but also goes to other connected grounding poles and is dispersed, an accurate combined resistance value cannot be measured. .

≪Multi-grounded earth arrestor≫
FIG. 4 is a diagram showing the measurement principle of the multiple grounding system earther. The multiple grounding system earther measures the grounding resistance of the ground which performs multiple grounding (also referred to as joint grounding). FIG. 4A shows the configuration of the grounding resistance of the ground that is multiple-grounded. Here, the ground resistance to be measured is Rx, and the other ground resistances are R ₁ , R ₂ ,..., R _n . R _{1 to} R _n are all considered to be connected in parallel, and can be regarded as one combined resistor. The combined resistance of R _{1 to} R _n is Rs. Since Rs is a combined resistance in which a plurality of resistors are connected in parallel, it can be regarded as being sufficiently small with respect to Rx. FIG. 4B shows an equivalent circuit having the configuration shown in FIG.

  FIG. 4C shows a configuration for measuring the resistance value of the equivalent circuit of FIG. When a voltage V is applied from the power source CT1 to the equivalent circuit, a current I corresponding to the ground resistance flows. If the voltage V is constant, the current I is inversely proportional to the resistance R (the combined resistance of Rx and Rs). Therefore, the current I is detected by the current detector CT2, and R is obtained by calculating V / I. be able to. At this time, the resistance R can be displayed as a measured value. However, as described above, since Rs can be considered to be sufficiently small with respect to Rx, the displayed measured value can be regarded as the measurement target Rx. it can.

However, when the number of ground resistors R1 to Rn is small, the combined resistance Rs cannot be sufficiently small with respect to Rx, and the measured value R cannot be regarded as Rx.
JP 2006-234800 A

  When grounding is performed using the articulated grounding method, it is necessary to measure the total combined resistance value. Here, since the measuring instrument of the ground resistance by the potential drop method is used for measuring a single ground resistance value, it is difficult to measure the combined resistance value. In addition, it is theoretically possible to measure the combined resistance value with two measuring devices using a multiple grounding system earthenster (clamp type), potential drop method, etc. However, since the measuring methods of the two measuring devices are different, there is an error. Becomes larger. Therefore, the combined resistance value cannot be accurately measured as described above, and the quality of the combined resistance value cannot be determined from the measured value at one connected point. Therefore, in order to obtain the combined resistance value, it is necessary to measure a plurality of connected locations, which is very complicated. Patent Document 1 discloses a ground resistance measuring device for obtaining a combined ground resistance of a joint ground system, but it is complicated because it is necessary to solve simultaneous equations.

  The present invention has been made in view of the above-mentioned problems, and its main object is to easily and accurately measure the ground resistance.

  In order to solve the above-mentioned problem, the present invention is a ground resistance measuring device, and includes a fixed resistor, first and second fixed terminals on both sides thereof, and a movable terminal that bisects the fixed resistor. A first power source and a first switch connected in series between a resistor, the movable terminal, and a first ground electrode whose ground resistance value is to be measured, and a second ground that is grounded to the ground A second power source and a second switch connected in series between the pole, the first fixed terminal, and the second ground pole, the first fixed terminal, and the second ground pole A third switch connected to bypass the second power source and the second switch, a first current detector for measuring a current flowing through the third switch, and a ground And a third ground electrode connected to the second fixed terminal, and the third ground electrode A second current detector for measuring the current flowing through, characterized in that it comprises a.

  According to this configuration, the movable terminal is positioned with respect to the fixed resistor of the variable resistor, and the first grounding electrode is based on the measured voltage of each current detector when the applied voltage of each power source and the state of each switch are switched. By calculating the grounding resistance, the grounding resistance can be measured easily and accurately.

The present invention is also a ground resistance measuring device, wherein the first switch is closed, the second switch is opened, and the third switch is set to a closed state, and the first switch Means for moving the movable terminal of the variable resistor so that the measured currents of the current detector and the second current detector are equal; the first switch is open; the second switch is closed; From the means for setting the third switch to each open state, the voltage of the second power source, and the measured current of the second current detector, the second ground electrode and the fixed of the variable resistor are fixed. Means for calculating a total resistance value of the resistor and the third grounding electrode, and storing the calculated value as a first resistance value; closing the first switch; opening the second switch; and opening the third switch Means for setting each state of the first power source From the voltage and the measured current of the second current detector, the third grounding electrode, the portion of the fixed resistance between the second fixed terminal and the movable terminal, and the entire first grounding electrode Means for calculating a resistance value and storing it as a second resistance value; subtracting a value obtained by dividing the first resistance value by 2 from the second resistance value; And a control unit including means for determining the ground resistance value of
According to this configuration, the ground resistance can be measured easily and accurately.

In addition, the present invention is a ground resistance measuring device, wherein the first power source and the second power source are integrated.
According to this configuration, since one power source is used to flow current to two locations, the manufacturing cost of the ground resistance measuring device can be suppressed.
In addition, the present invention is a ground resistance measurement device, wherein the first current detector and the second current detector are integrated.
According to this configuration, since one current detector is used to measure the current flowing in two places, the manufacturing cost of the ground resistance measuring device can be suppressed.

  The present invention is also a ground resistance measuring device, wherein the third grounding electrode is a connected grounding electrode or a single grounding electrode.

The present invention is also a ground resistance measuring method for measuring ground resistance using a ground resistance measuring device, wherein the first switch is closed, the second switch is opened, and the third switch is closed. Setting each state, moving the movable terminal of the variable resistor so that the measured currents of the first current detector and the second current detector are equal, and the first From the step of setting the switch to the open circuit, the second switch to the closed circuit, and the third switch to the open circuit, the voltage of the second power source and the measured current of the second current detector, Calculating a total resistance value of the second grounding pole, the fixed resistance of the variable resistor, and the third grounding pole and storing it as a first resistance value; closing the first switch; Open the switch of the first And setting the second switch among the fixed resistance from the voltage of the first power supply and the measured current of the second current detector. A step of calculating a total resistance value of a portion between the terminal and the movable terminal and the first ground electrode and storing it as a second resistance value; and from the second resistance value, the first resistance value Subtracting a value obtained by dividing the value by 2 and determining the value as a grounding resistance value of the first grounding electrode.
According to this method, the ground resistance can be measured easily and accurately.

  In addition, the problems disclosed in the present application and the solutions thereof will be clarified by the column of the best mode for carrying out the invention and the drawings.

  According to the present invention, the ground resistance can be measured easily and accurately.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. In the embodiment of the present invention, the ground resistance on the ground resistance measuring device side and the connected ground resistance to be measured constitute one series circuit including the ground. Then, the ground resistance (or its index value) on the ground resistance measuring device side is measured using the variable resistor and two auxiliary grounding poles provided in the ground resistance measuring device, while the ground resistance measuring device and the connected ground resistance are combined. Measure the ground resistance of the entire series circuit. Subsequently, the connection ground resistance is calculated by subtracting the ground resistance on the ground resistance measuring device side from the entire ground resistance. According to this, it is possible to efficiently and accurately measure the ground resistance of the object to be measured regardless of the connection ground or the single ground.

<< Device configuration >>
FIG. 1 is a diagram showing a circuit configuration of a ground resistance measuring apparatus according to an embodiment of the present invention. FIG. 1A shows a basic circuit of the ground resistance measuring apparatus 1. FIG. 1B shows an equivalent circuit of the basic circuit of FIG. In FIG. 1A, a connected grounding resistor 2 to be measured is configured by connecting grounding resistors R ₁ , R ₂ ,..., R _n−1 , R _n in parallel. For example, each ground resistance corresponds to one utility pole and is connected by an overhead wire. Each ground resistance is a value including the resistance value of the ground electrode and the influence of the ground. The ground resistance measuring device 1 for measuring the articulated ground resistance 2 includes a balancing adjustment resistance R _T , a first auxiliary grounding pole Q1, a second auxiliary grounding pole Q2, connection switches S1, S2, S3, a power source CT1, and a current detector. CT2 is connected.

Specifically, the balancing adjustment resistor _RT includes fixed terminals F1 and F2 on both sides and a movable terminal T in the middle. The fixed terminal F1 is connected to the first auxiliary grounding pole Q1 via the connection switch S2 and the power supply CT1, and further bypasses the connection switch S2 and the power supply CT1 between the fixed terminal F1 and the first auxiliary grounding pole Q1. A bypass path is provided, and a connection switch S3 is provided in the bypass path. The second auxiliary grounding electrode Q2 is connected to the fixed terminal F2. The movable terminal T is connected to the connection ground resistor 2 via the power source CT1 and the connection switch S1. The connection switch S1 is provided between the power supply CT1 and the connection ground resistor 2, but may be provided between the power supply CT1 and the movable terminal T. The connection switch S2 is provided between the power supply CT1 and the fixed terminal F1, but may be provided between the power supply CT1 and the first auxiliary grounding electrode Q1. A current detector CT2 is provided in the bypass path. Similarly, a current detector CT2 is provided between the fixed terminal F2 and the second auxiliary ground electrode Q2.

The balancing adjustment resistor _RT is a variable resistor for equalizing the currents flowing through the first auxiliary grounding electrode Q1 and the second auxiliary grounding electrode Q2, and is a fixed resistor (= R having fixed terminals F1 and F2 on both sides. _T) is the resistance _{R T1} of the fixed terminals F1 side by the movable terminal T, it is divided into a resistor _{R T2} of the stationary terminal F2 side _{(R T = R T1 + R} T2). The first auxiliary grounding electrode Q1 is connected to the balancing adjustment resistor _RT and the second auxiliary grounding electrode Q2 via the fixed terminal F1 when the connection switch S2 or S3 is closed.

Incidentally, the ground resistance R _K2 of the grounding resistor R _K1 and the second auxiliary ground electrode Q2 of the first auxiliary earth electrode Q1 is on the ground when installing the ground resistance measurement device 1 at the site to measure the articulation ground resistance 2 This is a grounding resistance of the auxiliary electrode to be provided, and has a value including the resistance value of the auxiliary electrode itself and the influence of the ground. Then, the ground resistance on the ground resistance measuring device 1 side (auxiliary ground electrode) is specified by balancing the ground resistance of both auxiliary ground electrodes using the balancing adjustment resistor _RT to absorb the influence. Can do. Details will be described later.

The connection switch S1 switches between a state in which current is supplied from the power source CT1 to the connected grounding resistor 2 and a state in which no current is supplied. The connection to the connection ground resistor 2 and the supply (injection) of current are performed through an overhead wire, for example. The connection switch S2 switches between a state in which current is supplied from the power source CT1 to the second auxiliary grounding electrode Q2 via the balancing adjustment resistor _RT and a state in which no current is supplied. The connection switch S3 switches between a state in which the first auxiliary grounding electrode Q1 and the balancing adjustment resistor _RT are short-circuited and an open state.

  The power source CT1 may be divided into a power source (first power source) for flowing current from the movable terminal T to the connected grounding resistor 2 and a power source (second power source) for flowing current to the first auxiliary grounding electrode Q1. Good. The power source CT1 is a constant current source, and the voltage value V can be calculated by integrating the current value and the internal resistance value. However, a constant voltage source may be used as the power source CT1. The current detector CT2 measures the difference between the currents flowing through the connection switch S3 and the second auxiliary grounding electrode Q2. If the current equal to the connection switch S3 and the second auxiliary grounding electrode Q2 is flowing, “0A Is shown. The current detector CT2 measures the current flowing through the connection switch S3 (first current detector), and measures the current flowing through the second auxiliary grounding electrode Q2 (second current detector). It may be divided into In that case, the currents indicated by the two current detectors are compared to determine whether they are equal. The power source CT1 and the current detector CT2 are mainly composed of a CT (Current Transformer).

≪Measurement method by the device and its principle≫
Next, a method for measuring the connection ground resistance and its principle will be described with reference to FIG. The following operation is performed by a control unit that controls the ground resistance measuring apparatus 1. The control unit is realized by a CPU (Central Processing Unit) executing a program stored in a predetermined memory. The control unit is additionally provided with a storage unit that stores data.

First, by setting the connection switch S1 to the closed state, S2 to the open state, and S3 to the closed state, the power source CT1 and the connected grounding resistor 2 are connected, and further, the first auxiliary grounding pole Q1 and the resistor _RT1 The second auxiliary grounding electrode Q2 and the resistor _RT2 are connected in parallel. In this connection state, the current flows from the power source CT1 to the connected grounding resistor 2, and is shunted to the first auxiliary grounding electrode Q1 and the second auxiliary grounding electrode Q2 through the ground, and the balancing adjustment resistor _RT and the movable terminal T To return to the power supply CT1. Therefore, the balancing adjustment resistance _RT is adjusted to equalize the currents flowing through the first auxiliary grounding electrode Q1 and the second auxiliary grounding electrode Q2. Specifically, the current detector CT2 to indicate 0A, moves the movable terminal T of the balanced-up adjusting resistor R _T. In this case, the first auxiliary ground electrode Q1, formed by balanced-up adjustment R _T resistor and the second auxiliary ground electrode Q2 is connected, out of the total resistance including a ground resistance, the first auxiliary ground electrode Q1 side resistor R _K1 '(= R _K1 + R _T1 ) is equal to the resistance R _K2 ' (= R _K2 + R _T2 ) on the second auxiliary grounding pole Q2 side (R _K1 + R _T + R _K2 = R _K1 '+ R _K2 ', R _K1 '= R _K2 ').

Next, the first auxiliary earthing pole Q1, the balancing adjustment resistor _RT and the second auxiliary earthing pole Q2 are connected in series by setting the connection switch S1 to open, S2 to closed, and S3 to open. Is done. In this connection state, the current returns from the power source CT1 to the power source CT1 through the balancing adjustment resistor R _T , the second auxiliary grounding electrode Q2, the ground, and the first auxiliary grounding electrode Q1. In this case, the resistance value of the series circuit is calculated from the applied voltage V from the power source CT1 and the measured current I from the current detector CT2, and stored in the storage unit. The measured value D1 of the resistance value is expressed by the following formula 1.
Measured value D1 = V / I = R _K1 + R _T + R _K2 = 2R _K1 '= 2R _K2 ' ... Formula 1

Subsequently, by setting the connection switch S1 to the closed state, S2 to the open state, and S3 to the open state, the power source CT1 and the connected grounding resistor 2 are connected, and further, the power source CT1 through the movable terminal T, The resistor _RT2 on the fixed terminal F2 side and the second auxiliary grounding electrode Q2 are connected. In this connected state, the current returns from the power source CT1 to the power source CT1 via the connection ground resistor 2, the ground, the second auxiliary grounding electrode Q2, and the resistor _RT2 on the fixed terminal F2 side. That is, the resistance R _T2 (R _K2 + R _T2 = R _K2 ′) on the second auxiliary grounding pole Q2 and the fixed terminal F2 side and the connection ground resistance R _S (R _S = 1 / (Σ1 / R _i [i = 1 to n]) ]) = 1 / (1 / R ₁ + 1 / R ₂ +... + 1 / R _n )). In this case, the resistance value of the entire circuit is calculated from the applied voltage V ′ by the power source CT1 and the measured current I ′ by the current detector CT2, and stored in the storage unit. The measured value D2 of the resistance value is expressed by the following equation 2.
Measurement value D2 = V ′ / I ′ = R _K2 + R _T2 + R _S = R _K2 '+ R _S ... Formula 2

From Equation 1 and Equation 2, the connected grounding resistance _RS can be obtained from the two measured values D1 and D2 as in Equation 3 below. Then, the obtained value may be output (displayed on a screen, transmitted to a network, etc.).
R _S = R _K2 ′ + R _S −R _K2 ′ = D2−D1 / 2 Equation 3

According to the above, since the resistance value _{RS of the} entire connected grounding resistance can be obtained from the difference in the measured value, not only the combined resistance value but also the single resistance value can be measured.

  Although the embodiment of the present invention has been described above, a recording medium that can be read by a computer by a program executed by the control unit in order to make each component in the ground resistance measuring apparatus 1 shown in FIG. It is assumed that the ground resistance measuring apparatus 1 according to the embodiment of the present invention is realized by recording the program on the computer and causing the computer to read and execute the recorded program. Note that the program may be provided to the computer via a network such as the Internet, or a semiconductor chip or the like in which the program is written may be incorporated in the computer.

  According to the embodiment of the present invention described above, it is possible to efficiently and accurately measure the combined resistance value of the entire grounding resistance in the connected grounding method. In addition, the combined resistance value and the single resistance value of the ground resistance can be easily and accurately measured by using one measuring device regardless of the connection ground or the single ground. Furthermore, not only the ground resistance to be measured, but also the ground resistance of the measuring device that is the basic data for the resistance value calculation is measured on site, and the procedure of the measurement method is concise, so the ground resistance can be measured at the facility location and measurer. The measurement error caused can be reduced.

  Although the best mode for carrying out the present invention has been described above, the above embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and equivalents thereof are also included in the present invention.

It is a figure which shows the circuit structure of the ground resistance measuring apparatus which concerns on embodiment of this invention, (a) shows the basic circuit of a ground resistance measuring apparatus, (b) shows the equivalent circuit of (a). It is a figure which shows the structure of an electric potential drop method, and an electric potential distribution curve, (a) shows the structure for implementing an electric potential drop method, (b) shows the electric potential distribution curve of each ground electrode used by an electric potential drop method. , (C) shows two types of potential distribution curves. It is a figure which shows the structure at the time of trying to measure the synthetic | combination resistance value of a connection grounding resistance using a voltage drop method. It is a figure which shows the measurement principle of a multiple earthing | grounding system earthenster, (a) shows the structure of the earthing | grounding resistance of the earth grounded by multiple earthing, (b) shows the equivalent circuit of the structure of (a), (c) is The structure for measuring the resistance value of the equivalent circuit of (b) is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ground resistance measuring apparatus 2 Articulated ground resistance _RT Resistance for balance adjustment (variable resistor, fixed resistance)
R _T1 fixed terminal F1 side resistance R _T2 fixed terminal F2 side resistance (the portion of the fixed resistance between the second fixed terminal and the movable terminal)
F1 fixed terminal (first fixed terminal)
F2 fixed terminal (second fixed terminal)
T Movable terminal Q1 First auxiliary grounding electrode (second grounding electrode)
Q2 Second auxiliary grounding electrode (third grounding electrode)
R _K1 earth resistance R ₁ to R _n articulating ground resistance according to the ground resistance R _K2 second auxiliary ground electrode Q2 of the first auxiliary ground electrode Q1 (the first ground electrode)
S1 connection switch (first switch)
S2 connection switch (second switch)
S3 connection switch (third switch)
CT1 power supply (first power supply, second power supply)
CT2 current detector (first current detector, second current detector)

Claims (6)

A variable resistor comprising a fixed resistor, first and second fixed terminals on both sides thereof, and a movable terminal that bisects the fixed resistor;
A first power source and a first switch connected in series between the movable terminal and a first grounding electrode whose ground resistance value is to be measured;
A second grounding electrode grounded to the ground;
A second power source and a second switch connected in series between the first fixed terminal and the second ground electrode;
A third switch connected between the first fixed terminal and the second grounding electrode so as to bypass the second power source and the second switch;
A first current detector for measuring a current flowing through the third switch;
A third grounding electrode grounded to the ground and connected to the second fixed terminal;
A second current detector for measuring a current flowing through the third ground electrode;
A ground resistance measuring apparatus comprising: The ground resistance measuring device according to claim 1,
Means for setting the first switch to a closed state, the second switch to an open circuit, and the third switch to a closed state;
Means for moving the movable terminal of the variable resistor so that the measured currents of the first current detector and the second current detector are equal;
Means for setting the first switch to an open state, the second switch to a close state, and the third switch to an open state;
From the voltage of the second power supply and the measured current of the second current detector, calculate the total resistance value of the second ground electrode, the fixed resistor of the variable resistor, and the third ground electrode, Means for storing as a first resistance value;
Means for setting the first switch to a closed state, the second switch to an open state, and the third switch to an open state;
From the voltage of the first power supply and the measured current of the second current detector, the third grounding electrode, the portion of the fixed resistance between the second fixed terminal and the movable terminal, and the first Means for calculating a total resistance value of one grounding electrode and storing it as a second resistance value;
Means for subtracting a value obtained by dividing the first resistance value by 2 from the second resistance value and determining the value as a ground resistance value of the first ground electrode;
A grounding resistance measuring apparatus, further comprising a control unit including: The ground resistance measuring device according to claim 1 or 2,
The first power supply and the second power supply are integrated with each other. The ground resistance measuring apparatus according to claim 1, wherein the first power supply and the second power supply are integrated. The ground resistance measuring device according to claim 1 or 2,
The ground resistance measuring device, wherein the first current detector and the second current detector are integrated. The ground resistance measuring device according to any one of claims 1 to 4,
The third grounding electrode is a connected grounding electrode or a single grounding electrode. A ground resistance measurement method for measuring ground resistance using the ground resistance measurement device according to claim 1,
Setting the first switch to a closed state, the second switch to an open circuit, and the third switch to a closed state;
Moving the movable terminal of the variable resistor so that the measured currents of the first current detector and the second current detector are equal;
Opening the first switch, setting the second switch closed, and setting the third switch open;
From the voltage of the second power supply and the measured current of the second current detector, calculate the total resistance value of the second ground electrode, the fixed resistor of the variable resistor, and the third ground electrode, Storing as a first resistance value;
Setting the first switch to a closed state, the second switch to an open state, and the third switch to an open state;
From the voltage of the first power supply and the measured current of the second current detector, the third grounding electrode, the portion of the fixed resistance between the second fixed terminal and the movable terminal, and the first Calculating an overall resistance value of one grounding electrode and storing it as a second resistance value;
Subtracting a value obtained by dividing the first resistance value by 2 from the second resistance value, and determining the value as a ground resistance value of the first ground electrode;
A method of measuring ground resistance, characterized in that

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