JP2014153324A - Measuring method and measuring device of ground resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method and a measuring device capable of measuring a ground resistance with high accuracy.SOLUTION: The measuring method of the ground resistance includes: a ground electrode installing step of burying a ground electrode 2 connected to an AC power supply 31 under a ground; a voltage auxiliary electrode installing step of connecting a voltage auxiliary electrode 4 to the DC power supply 31 via a first inductor L1 and disposing the voltage auxiliary electrode 4 on the ground at a position away from the ground electrode 2; a current auxiliary electrode installing step of connecting a current auxiliary electrode 5 to the DC power supply 31 via a second inductor L2 and disposing the current auxiliary electrode 5 on the ground at a position away from the ground electrode 2 and the voltage auxiliary electrode 4; a measuring step of measuring a potential of the ground pole 2 and the current flowing through the current auxiliary electrode 5; and a calculation step of calculating a ratio of the potential of the ground electrode 2 measured in the measuring step to the current flowing through the current auxiliary electrode 5 as a ground resistance. The first inductor L1 and the second inductor L2 are disposed at a position away from the ground electrode 2 by a predetermined distance.

Description

  The present invention relates to a measurement method and a measurement apparatus for measuring a ground resistance from a current flowing through a ground electrode and a potential of the ground electrode.

  When the ground current I [A] flows into the ground electrode buried in the ground, the potential of the ground electrode becomes E [V] higher than the surrounding ground. The ratio E / I [Ω] of the potential rise and the ground current at this time is defined as the ground resistance.

  Generally, in order to measure the ground resistance, a measurement method called a triode method is performed. In the triode method, the current auxiliary electrode is installed at a position appropriately separated from the ground electrode (specifically, each resistance area (a position where most of the ground resistance is included around the electrode) does not interfere), The ground electrode and the current auxiliary electrode are connected through an AC power source and an ammeter. In addition, a voltage auxiliary electrode is installed at a position appropriately separated from the ground electrode (specifically, outside the respective resistance areas of the ground electrode and the current auxiliary electrode), and the ground electrode and the voltage auxiliary electrode are connected via a voltmeter. And ground resistance is calculated | required from the value which an ammeter and a voltmeter show when an electric current is sent from the AC power source to the ground electrode.

  Conventionally, in a measuring device that measures the ground resistance by the triode method, a capacitor is formed between each auxiliary electrode and the ground by placing the voltage auxiliary electrode and the current auxiliary electrode on the ground without being embedded in the ground. In other words, there are known devices that allow current to flow (see, for example, Patent Documents 1 and 2).

  Conventionally, there is also known a measuring device that measures the ground resistance by placing two return lines connected to an AC power source to which a ground electrode is connected via an inductor on the ground without being embedded in the ground (for example, And Patent Document 3). In this measuring apparatus, an RLC series resonance circuit is formed, and the ground resistance is calculated from the impedance at the time of resonance. Specifically, in this measuring apparatus, a closed loop circuit formed between a ground electrode and one return line, a closed loop circuit formed between the ground electrode and two return lines, and two The impedance at the time of resonance is measured by each of three circuits including a closed loop circuit formed between the three return lines and the ground resistance is calculated from these three values.

JP-A-50-113267 JP 52-53472 A Japanese Patent No. 4778922

  By the way, in the three-pole method, the current auxiliary electrode and the resistance area of the ground electrode must be arranged sufficiently apart from each other so that they do not interfere with each other. However, as shown in FIG. 6, the measuring devices described in Patent Documents 1 and 2 use a high frequency current so that a current flows between the current auxiliary electrode 130 and the ground. In addition, the lead wire 140 connecting the current auxiliary electrode 130 and the AC power source 120 also forms a capacitor with the ground. That is, even if the current auxiliary electrode 130 is arranged at a distance from the ground electrode 110, current flows between the lead wire 140 located closer to the ground electrode 110 than the current auxiliary electrode 130 and the ground. The flowing current and the resistance area A2 due to the current auxiliary electrode 130 may affect the resistance area A1 of the ground electrode 110, and an error may occur in the measured ground resistance.

  In the three-pole method, the voltage auxiliary electrode and the ground electrode must be sufficiently separated from each other in order to measure the potential increase of the ground electrode with respect to zero potential. However, in the measuring apparatus described in Patent Documents 1 and 2, as shown in FIG. 6, the voltage auxiliary electrode 150 and the AC power source 120 are connected in the same manner as the lead wire 140 that connects the current auxiliary electrode 130 and the AC power source 120 described above. The connecting lead wire 170 also forms a capacitor with the ground. As a result, the voltage measured by the voltmeter 160 is not only the potential difference between the voltage auxiliary electrode 150 and the ground electrode 110 disposed at a position where the potential is zero, but also the lead wire 170 disposed at a position other than the zero potential. A potential difference from the ground electrode 110 is also included. As a result, the potential rise of the ground electrode 110 with respect to zero potential cannot be measured accurately, and there is a problem that an error occurs in the measured ground resistance.

As shown in FIG. 7, if the internal impedance of the voltmeter is Z _V , the impedance of the voltage auxiliary electrode 250 is V _P , the ground resistance of the ground electrode is R ₀ , and the current flowing through the ground electrode is i, the voltmeter 260 The voltage V _V measured at
V _V = {Z _V / (Z _V + Z _P )} × R ₀ × i
It is represented by Therefore, the ground resistance R ₀ of the ground electrode is
R ₀ = {(Z _V + Z _P ) / Z _V } × (V _V / i)
It becomes. That is, when the ground resistance is calculated from the measured value of the voltmeter 260 and the measured value of the ammeter 220 (when the ground resistance R ₀ is calculated as R ₀ = V _V / i), the impedance Z _P of the voltage auxiliary electrode 250 is be sufficiently smaller than the internal impedance Z _V of the voltmeter 260, a large error in the grounding resistance and the calculated and the actual ground resistance occurs. However, the measuring apparatus described in Patent Documents 1 and 2, can not be ignored impedance Z _P of the voltage auxiliary electrode 250, there is a possibility that measurement error increases.

  The measuring apparatus described in Patent Document 3 can measure at a lower frequency than the measuring apparatus described in Patent Documents 1 and 2 by using an RLC series resonance circuit. However, the measuring method using this measuring apparatus does not use the triode method. This measurement method also takes into account the measurement error due to the capacitance between each return line and the ground and the ground return impedance, but the ground potential due to the ground resistivity that must be taken into account most. The effect of the rise is not taken into account. That is, this measurement method does not include the concept of resistance area interference in ground resistance measurement. Therefore, no mention is made of the location of the inductor.

  Therefore, an object of the present invention is to provide a measurement method and a measurement apparatus that can improve the measurement accuracy of ground resistance.

  In order to achieve the above-described object, the ground resistance measuring method according to the present invention includes a ground electrode installation step in which a ground electrode connected to an AC power source is buried in the ground and a voltage auxiliary electrode between the AC power source and the first. A voltage auxiliary electrode installation step of connecting to the AC power supply via an inductor and disposing the auxiliary voltage electrode on the ground at a position away from the ground electrode, and a current auxiliary electrode between the AC power supply and a second inductor. In this state, the current auxiliary electrode is disposed on the ground at a position away from the ground electrode and the voltage auxiliary electrode, and the electric potential of the ground electrode and the current flowing through the current auxiliary electrode And measuring the ground resistance by calculating a ratio of the potential of the grounding electrode measured in the measuring step and the current flowing through the current auxiliary electrode as a grounding resistance. A measuring method, the first inductor and the second inductor, characterized in that arranged at a position a predetermined distance away from the earth electrode.

  According to such a measurement method, since the first inductor and the second inductor are separated from the ground electrode by a predetermined distance, the ground electrode and the first inductor at a position where they interfere with the resistance area of the ground electrode during measurement, and The leakage of current between the ground electrode and the second inductor is negligible and does not interfere with the resistance area of the ground electrode, so that the measurement accuracy of the ground resistance can be improved.

  Note that the predetermined distance is desirably 10 m or more, which is a separation distance that is generally considered to prevent interference between the ground electrode and the resistance area of each electrode.

  The second inductor is preferably attached to the current auxiliary electrode. The first inductor may be attached to the voltage auxiliary electrode.

  The measuring method includes a first current confirmation step of adjusting an inductance of the second inductor, a ground area of the current auxiliary electrode, or a frequency of the AC power supply so that a current flows through the current auxiliary electrode. It is desirable to provide.

  The measuring method may include a second current confirmation step of adjusting an inductance of the first inductor, a ground area of the voltage auxiliary electrode, or a frequency of the AC power supply so that a current flows through the voltage auxiliary electrode. It is desirable to provide.

  By having such a first current confirmation step and a second current confirmation step, it is possible to confirm that the impedance of the voltage auxiliary electrode is an appropriate value for the measurement, and therefore it is possible to reduce measurement errors. .

  And in the measurement method described above, in the voltage auxiliary electrode installation step or the current auxiliary electrode installation step, a straight line connecting the ground electrode and the voltage auxiliary electrode, and a straight line connecting the ground electrode and the current auxiliary electrode, It is desirable to arrange the voltage auxiliary electrode and the current auxiliary electrode so as to form 90 to 180 degrees.

  According to such a measuring method, since the first lead wire and the second lead wire are separated from each other, when a current flows, a capacitor is formed between the lead wires, and the current is prevented from flowing between them. can do.

  The measuring device for measuring the ground resistance according to the present invention includes a grounding electrode embedded in the ground, an AC power source connected to the grounding electrode by a first lead wire, and a position away from the grounding electrode. A voltage auxiliary electrode disposed on the ground and connected to the AC power source by a second lead wire, and disposed on the ground at a position away from the ground electrode and the voltage auxiliary electrode, and connected to the AC power source by a third lead wire A measuring device for measuring a ground resistance used for calculating a ratio of a potential of the ground electrode and a current flowing through the current auxiliary electrode as a ground resistance. The voltage auxiliary electrode is connected to the AC power source via a first inductor, the current auxiliary electrode is connected to the AC power source via a second inductor, and the first inductor is Two lead wires or the voltage auxiliary electrode is provided at a position that can be separated from the ground electrode by a predetermined distance or more, and the second inductor is provided at a predetermined distance from the ground electrode in the third lead wire or the current auxiliary electrode. It is provided in the position which can be separated.

  According to the measuring apparatus configured as described above, the first inductor disposed between the AC power source and the voltage auxiliary electrode, and the second inductor disposed between the AC power source and the current auxiliary electrode are separated from the ground electrode. It is possible to arrange them at positions separated by a predetermined distance. Thus, during measurement, current leakage between the ground electrode and the first inductor, and between the ground electrode and the second inductor at a position that interferes with the resistance region of the ground electrode is negligible. Therefore, the measurement accuracy of the ground resistance can be improved.

  Note that the predetermined distance is desirably 10 m or more, which is a separation distance that is generally considered to prevent interference between the ground electrode and the resistance area of each electrode.

  The second inductor is preferably attached to the current auxiliary electrode.

  With this configuration, the installation of the second inductor and the current auxiliary electrode is simplified.

  The first inductor may be attached to the voltage auxiliary electrode.

  With this configuration, the installation of the first inductor and the voltage auxiliary electrode is simplified.

  In addition, it is desirable that at least one of the first inductor and the second inductor has variable inductance.

  With this configuration, by adjusting the inductance of the inductor, it is possible to adjust according to the measurement environment so that a current flows through a circuit provided with the inductance. That is, when the inductance of the first inductor is variable, the inductance of the first inductor can be adjusted according to the measurement environment so that a current flows between the ground electrode and the voltage auxiliary electrode. When the inductance of the second inductor is variable, the inductance of the second inductor can be adjusted according to the measurement environment so that a current flows between the ground electrode and the current auxiliary electrode.

  In the measuring apparatus, the AC power source and the voltage auxiliary electrode are connected, the AC power source and the voltage auxiliary electrode are connected, and the AC power source and the current auxiliary electrode are connected. It is desirable to provide a switcher capable of switching the circuits.

  According to the measuring apparatus configured in this way, it is not necessary to reconfigure the circuit manually for each measurement stage, so that work efficiency is good.

  According to the present invention, since the first inductor and the second inductor are separated from each other by a predetermined distance, the ground electrode, the first inductor, and the ground electrode at a position where they interfere with the resistance area of the ground electrode during measurement. The leakage of current between the second inductor and the second inductor is negligible and does not interfere with the resistance area of the ground electrode, so that the measurement accuracy of the ground resistance can be improved.

It is a circuit diagram which shows the measuring apparatus which concerns on one Embodiment of this invention. It is a figure which shows the measurement apparatus when measuring ground resistance, and is a figure which shows arrangement | positioning of a ground electrode, a voltage auxiliary electrode, and a current auxiliary electrode when measuring ground resistance. It is a circuit diagram which shows the state which switched the circuit with the switch from the state of FIG. It is a figure which shows the measuring apparatus in a 1st modification. It is a figure which shows the measuring apparatus in a 2nd modification. It is a figure which shows the interference of the resistance area in a prior art. It is an equivalent circuit schematic of the measuring apparatus in a prior art.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

<Measurement device>
The measuring device 1 of the present invention is a device for measuring the ground resistance by the triode method. The measuring apparatus 1 includes a ground electrode 2, a measuring instrument 3, a voltage auxiliary electrode 4, a current auxiliary electrode 5, a first inductor L1, and a second inductor L2.

  The ground electrode 2 is an electrode embedded in the ground when measuring the ground resistance. The ground electrode 2 can be connected to the AC power supply 31 by being connected to a terminal E of the measuring instrument 3 described later by the first lead wire 6. The first lead wire 6 is preferably about 1 m long in order to minimize the influence of the impedance of the first lead wire 6 itself on the measurement.

  For example, the measuring device 3 measures a grounding resistance by passing a current through a connected electrode by pressing a button provided on the main body, and displays the value of the grounding resistance on a display provided on the main body. It is.

  The measuring instrument 3 includes an AC power supply 31 capable of changing the frequency, an ammeter 32 connected to the AC power supply 31, a voltmeter 33, a switch 34 for switching circuits, and a control unit 35. Has been. Further, the measuring instrument 3 is provided with a terminal E, a terminal P and a terminal C to which a lead wire can be connected from the outside. The voltmeter 33 is connected to the terminal E.

  The switch 34 operates, for example, by operating a lever provided on the main body of the measuring instrument 3 so that the terminal E and the terminal P are connected to the AC power source 31 (the state shown in FIG. 1), the terminal E and The circuit can be switched to a second state (the state shown in FIG. 3) in which the terminal P is connected to the AC power supply 31 and the terminals E and P are connected to the voltmeter 33.

  Specifically, the switch 34 includes a first contact 34A connected to the ammeter 32, a second contact 34B connected to the AC power supply 31, a third contact 34C connected to the voltmeter 33, and a terminal C. A fourth contact 34D connected to the terminal E, a fifth contact 34E connected to the terminal E, and a sixth contact 34F connected to the terminal P.

  In the first state, the switch 34 connects the first contact 34A and the fifth contact 34E, and the second contact 34B and the sixth contact 34F. In the second state, the switch 34 connects the first contact 34A and the fourth contact 34D, the second contact 34B and the fifth contact 34E, and the third contact 34C and the sixth contact 34F.

  The control unit 35 includes a recording device that records the frequency of the current output from the AC power supply 31, the current value measured by the ammeter 32, and the voltage measured by the voltmeter 33, and the ground resistance based on the value recorded by the recording device. And a processing / arithmetic unit for computing When the current value measured by the ammeter 32 is I [A] and the voltage measured by the voltmeter 33 is E [V], the processing / arithmetic unit calculates the ratio E / I [Ω] as the ground resistance. To do.

  The measuring instrument 3 is a display for confirming that the current has flowed in the main body so that the person who performs the measurement can change the measurement conditions while confirming that the current is flowing in the circuit. It is desirable that a section is provided. This display unit can be constituted by, for example, a meter that displays the current value measured by the ammeter 32, a lamp that emits light when a current flows through the circuit, and the like.

  The voltage auxiliary electrode 4 is a sheet-like electrode arranged on the ground at a position away from the ground electrode 2. This voltage auxiliary electrode 4 can be connected to a terminal P of the measuring instrument 3 by a second lead wire 7 described later.

  The first inductor L1 is an inductor having a variable inductance, and is directly attached to the voltage auxiliary electrode 4 (see FIG. 2). The first inductor L1 is connected to the terminal P of the measuring instrument 3 by the second lead wire 7. Thereby, the voltage auxiliary electrode 4 is connected to the AC power supply 31 by the second lead wire 7 through the first inductor L1.

  The second lead wire 7 is arranged such that the first inductor L1 and the voltage auxiliary electrode 4 are separated from the ground electrode 2 by a predetermined distance, more specifically, a separation distance or more according to the scale (size or amount of embedding) of the ground electrode 2. For example, it has a length of 10 m or more.

  The current auxiliary electrode 5 is a sheet-like electrode disposed on the ground at a position away from the ground electrode 2 and the voltage auxiliary electrode 4. The current auxiliary electrode 5 can be connected to a terminal C of the measuring instrument 3 by a third lead wire 8 described later.

  The second inductor L2 is an inductor having a variable inductance, and is directly attached to the current auxiliary electrode 5 (see FIG. 2). The second inductor L2 is connected to the terminal C of the measuring device 3 by the third lead wire 8. Thereby, the current auxiliary electrode 5 is connected to the AC power supply 31 by the third lead wire 8 through the second inductor L2.

  Similar to the second lead wire 7, the third lead wire 8 is a predetermined distance from the ground electrode 2, and more specifically, a separation distance corresponding to the scale of the ground electrode 2, from the second inductor L 2 and the current auxiliary electrode 5. For example, it has a length of 10 m or more so that it can be separated as described above.

<Measurement method>
Next, a measurement method for measuring the ground resistance by the triode method using the measurement apparatus 1 configured as described above will be described.

  First, as shown in FIG. 2 (a), the ground electrode 2 is connected to the terminal E of the measuring instrument 3 by the first lead wire 6, and installed on the ground at a target point (ground electrode installation step).

  And the 2nd lead wire 7 is connected to the terminal P of the measuring device 3, and the voltage auxiliary electrode 4 is connected to the alternating current power supply 31 via the 1st inductor L1 between the alternating current power supplies 31. Then, the voltage auxiliary electrode 4 is installed on the ground at a position away from the ground electrode 2 (voltage auxiliary electrode installation step). At this time, the first inductor L1 is disposed at a position away from the ground electrode 2 by a predetermined distance (10 m or more), and the voltage auxiliary electrode 4 is disposed at a position farther from the ground electrode 2 than the first inductor L1.

  Further, the third lead wire 8 is connected to the terminal C of the measuring instrument 3, and the current auxiliary electrode 5 is connected to the AC power source 31 with the second inductor L <b> 2 between the AC power source 31. Then, the current auxiliary electrode 5 is disposed on the ground at a position away from the ground electrode 2 and the voltage auxiliary electrode 4 (current auxiliary electrode installation step). At this time, the second inductor L2 is disposed at a position away from the ground electrode 2 by a predetermined distance (10 m or more), and the current auxiliary electrode 5 is disposed at a position farther from the ground electrode 2 than the second inductor L2. Further, as shown in FIG. 2B, the ground electrode 2 is formed such that a straight line A connecting the ground electrode 2 and the voltage auxiliary electrode 4 and a straight line B connecting the ground electrode 2 and the current auxiliary electrode 5 form 180 degrees. 2, the third lead wire 8 is extended to the opposite side of the voltage auxiliary electrode 4, and the current auxiliary electrode 5 is disposed on the third lead wire 8.

  When the installation of the ground electrode 2, the voltage auxiliary electrode 4 and the current auxiliary electrode 5 is completed, the measuring device 3 is operated to set the switch 34 to the first state. Thereby, as shown in FIG. 1, the alternating current power supply 31 and the voltage auxiliary electrode 4 are connected. More specifically, when the switch 34 is in the first state, the ground electrode 2 is connected to the AC power source 31 via the ammeter 32, and the voltage auxiliary electrode 4 is connected to the AC power source 31 via the first inductor L1. Is done. That is, a circuit in which the ammeter 32, the AC power supply 31, and the first inductor L1 are connected in series is formed between the ground electrode 2 and the auxiliary voltage electrode 4.

  Next, in order to determine the frequency when measuring the ground resistance, the frequency of the AC power supply 31 is adjusted while confirming the display unit of the measuring instrument 3 so as to resonate and the current flows through the voltage auxiliary electrode 4 (first). 2 current confirmation process). At this time, the inductance of the first inductor L1 and the ground area of the voltage auxiliary electrode 4 are fixed.

  In the second current confirmation step, when it is confirmed that a current has flowed through the voltage auxiliary electrode 4, the measuring device 3 is operated to switch the switch 34 to the second state. Thereby, as shown in FIG. 3, the AC power supply 31 and the voltage auxiliary electrode 4 are connected, and the AC power supply 31 and the current auxiliary electrode 5 are connected. More specifically, when the switch 34 is in the second state, the ground electrode 2 is connected to the AC power source 31, and the current auxiliary electrode 5 is connected to the AC power source 31 via the second inductor L 2 and the ammeter 32. . The ground electrode 2 and the voltage auxiliary electrode 4 are connected to each other via the voltmeter 33 and the first inductor L1. That is, the second inductor L 2, the ammeter 32 and the AC power supply 31 are connected in series between the current auxiliary electrode 5 and the ground electrode 2, and the voltmeter 33 connected to the voltage auxiliary electrode 4 is connected to the ground electrode 2. A circuit connected in parallel is formed.

  Next, in a state where the frequency of the AC power supply 31 is fixed to the frequency when the current flows through the voltage auxiliary electrode 4 in the second current confirmation step, the measuring device is configured to resonate and flow the current through the current auxiliary electrode 5. 3 is adjusted while adjusting the inductance of the second inductor L2 (first current confirmation step).

  In the first current confirmation step, when it is confirmed that a current has flowed through the current auxiliary electrode 5, the button of the measuring device 3 is pressed to start measurement. At this time, the potential of the ground electrode 2 is measured by the voltmeter 33 in the measuring instrument 3, and the current flowing through the current auxiliary electrode 5 is measured by the ammeter 32 (measuring process). Then, based on these measurement results, the control unit 35 determines the ground resistance (the ratio E / I [Ω] of the potential E [V] of the ground electrode 2 measured in the measurement process and the current I [A] flowing through the current auxiliary electrode 5). ]) Is calculated (calculation step), and the calculated ground resistance is displayed on the display of the measuring instrument 3.

  The following actions and effects can be obtained by performing the ground resistance measurement method using the measuring apparatus 1 as described above.

  Since the first inductor L1 and the second inductor L2 are separated from the grounding electrode 2 by a predetermined distance (generally, a separation distance of 10 m or more that the resistance area of the grounding electrode 2 and each electrode does not interfere with each other), The leakage of current between the grounding electrode 2 and the first inductor L1 and the grounding electrode 2 and the second inductor L2 at a position interfering with the resistance area of the grounding electrode 2 is negligible. Since it does not interfere with the area, the measurement accuracy of the ground resistance can be improved.

  In addition, by performing the first current confirmation step and the second current confirmation step, it is possible to confirm that the impedance of the voltage auxiliary electrode 4 is an appropriate value for measurement, so that measurement errors can be reduced.

  In the current auxiliary electrode installation step, the voltage auxiliary electrode 4 and the voltage auxiliary electrode 4 so that the straight line A connecting the ground electrode 2 and the voltage auxiliary electrode 4 and the straight line B connecting the ground electrode 2 and the current auxiliary electrode 5 form 180 degrees. Since the current auxiliary electrode 5 is disposed, it is possible to suppress a gap between the second lead wire 7 and the third lead wire 8 from being a capacitor.

  Further, since the first inductor L1 is attached to the voltage auxiliary electrode 4 and the second inductor L2 is attached to the current auxiliary electrode 5, the installation is simpler than the case where these are provided as separate parts. become.

  Since the circuit 34 can be switched between the first state and the second state by the switch 34 provided in the measuring device 3, it is not necessary to manually reconfigure the circuit at each measurement stage, and the working efficiency is improved. Good.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the said embodiment, although the 1st inductor L1 was attached to the voltage auxiliary electrode 4, this invention is not limited to this. For example, as shown in FIG. 4, the first inductor L <b> 1 and the voltage auxiliary electrode 4 are separate components, and may be connected by a fourth lead wire 9. The length of the fourth lead wire 9 connected to the first inductor L1 and the voltage auxiliary electrode 4 is not particularly limited. The first inductor L1 is connected to the measuring instrument 3 by a second lead wire 7 having a length of 10 m or more so that the first inductor L1 can be disposed at a position away from the ground electrode 2 by a predetermined distance (10 m or more).

  Thus, even when the first inductor L1 and the voltage auxiliary electrode 4 are connected by the fourth lead wire 9, the first inductor L1 and the voltage auxiliary electrode 4 are separated from the ground electrode 2 by a predetermined distance (10 m or more). Since the current can leak from the fourth lead wire 9, the leaked current does not affect the resistance area of the ground electrode 2. Thereby, the measurement accuracy of the ground resistance can be improved.

  Moreover, in the said embodiment, although the 2nd inductor L2 was attached to the current auxiliary electrode 5, this invention is not limited to this. For example, as shown in FIG. 4, the second inductor L <b> 2 and the current auxiliary electrode 5 are separate components, and may be connected by a fifth lead wire 10. Note that the length of the fifth lead wire 10 connected to the second inductor L2 and the current auxiliary electrode 5 is not particularly limited. The second inductor L2 is connected to the measuring instrument 3 by a third lead wire 8 having a length of 10 m or more so that the second inductor L2 can be disposed at a position away from the ground electrode 2 by a predetermined distance (10 m or more).

  Even in such a case, since the second inductor L2 and the current auxiliary electrode 5 can be arranged at a predetermined distance (10 m or more) from the ground electrode 2, even if current leaks from the fifth lead wire 10. The leaked current does not affect the resistance area of the ground electrode 2. Thereby, the measurement accuracy of the ground resistance can be improved.

  And in the said embodiment, although the 1st current check process was performed after the 2nd current check process, the present invention is not limited to this, and after performing the 1st current check process, the 2nd current check process is performed. May be.

  In the embodiment, in the second current confirmation step, the frequency of the AC power supply 31 is adjusted in a state where the inductance of the first inductor L1 and the ground area of the voltage auxiliary electrode 4 are fixed so that the current flows through the voltage auxiliary electrode 4. However, the present invention is not limited to this. For example, the inductance of the first inductor L1 may be adjusted in a state where the frequency of the AC power supply 31 and the ground area of the voltage auxiliary electrode 4 are fixed, or the frequency of the AC power supply 31 and the inductance of the first inductor L1 are fixed. In the state, the ground area of the voltage auxiliary electrode 4 may be adjusted.

  In the first embodiment, in the first current confirmation step, the inductance of the second inductor L2 is fixed with the frequency of the AC power supply 31 and the ground area of the current auxiliary electrode 5 fixed so that the current flows through the current auxiliary electrode 5. However, the present invention is not limited to this. For example, the ground area of the current auxiliary electrode 5 may be adjusted in a state where the inductance of the second inductor L2 and the frequency of the AC power supply 31 are fixed, or the first current confirmation step is performed before the second current confirmation step. When performing, the frequency of the AC power supply 31 may be adjusted in a state where the inductance of the second inductor L2 and the ground area of the current auxiliary electrode 5 are fixed.

  In the embodiment, the voltage auxiliary electrode 4 and the current auxiliary electrode 5 are sheet-like electrodes. However, the present invention is not limited to this, and the voltage auxiliary electrode 4 and the current auxiliary electrode 5 have a certain thickness (rigidity). A certain plate-like electrode may be sufficient.

  In the embodiment, in the current auxiliary electrode installation step, the voltage auxiliary is performed so that the straight line A connecting the ground electrode 2 and the voltage auxiliary electrode 4 and the straight line B connecting the ground electrode 2 and the current auxiliary electrode 5 form 180 degrees. Although the electrode 4 and the current auxiliary electrode 5 are arranged, the present invention is not limited to this, and the voltage auxiliary electrode 4 and the current auxiliary electrode 5 may be arranged so that the straight lines A and B are 90 degrees or more. .

  In the above embodiment, the measuring device 3 is configured to calculate the ground resistance from the measured potential of the ground electrode 2 and the current flowing through the current auxiliary electrode 5 and display it on the display. It is not limited. For example, the measuring device may only display the current value measured by the ammeter and the voltage measured by the voltmeter. That is, the calculation step of calculating the ground resistance may be performed by the person who performs the measurement by calculating the ratio of the potential of the ground electrode 2 displayed on the display and the current flowing through the current auxiliary electrode 5.

  In the above embodiment, the measurement of the ground resistance is started by pressing the button of the measuring device 3, but the present invention is not limited to this, and the measuring device includes the switch 34 as the first. When the two states are set, the ground resistance may be calculated and displayed on the display.

  In the above-described embodiment, the display unit for confirming that a current has flowed in the circuit is provided in the measuring instrument 3, but the present invention is not limited to this, and the lamp that emits light when the current flows is voltage-assisted. It may be provided on the electrode 4 or the current auxiliary electrode 5.

  In the above embodiment, the measuring instrument 3 is provided with three terminals (terminal C, terminal E, terminal P) to which lead wires are connected. However, the present invention is not limited to this, and for example, FIG. As shown in FIG. 3, the measuring instrument 3A may be provided with four terminals (terminal C, terminal E1, terminal E2, and terminal P).

  In this measuring instrument 3A, the terminal E1 is connected to the fifth contact 34E, and the terminal E2 is connected to the voltmeter 33. The ground electrode 2 is connected to the terminal E1 of the measuring instrument 3A by the sixth lead wire 61, and is connected to the sixth lead wire 61 in the vicinity of the ground electrode 2 by the seventh lead wire 62. Connected to E2. Thereby, since the voltmeter 33 is connected in parallel with the ground electrode 2 in the vicinity of the ground electrode 2, the potential in the vicinity of the ground electrode 2 can be measured by the voltmeter 33. Therefore, even if the sixth lead wire 61 connecting the ground electrode 2 and the measuring instrument 3A is longer than 1 m, the ground resistance can be measured without being affected by the impedance of the sixth lead wire 61 itself.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 2 Ground electrode 4 Voltage auxiliary electrode 5 Current auxiliary electrode 6 1st lead wire 7 2nd lead wire 8 3rd lead wire 31 AC power supply 34 Switch L1 1st inductor L2 2nd inductor

Claims (6)

A grounding electrode installation process in which a grounding electrode connected to an AC power source is buried in the ground;
A voltage auxiliary electrode installation step of connecting the voltage auxiliary electrode to the AC power source through a first inductor between the AC power source and disposing the voltage auxiliary electrode on the ground at a position away from the ground electrode;
A current auxiliary electrode installation step of connecting the current auxiliary electrode to the AC power source via a second inductor between the AC power source and disposing the current auxiliary electrode on the ground at a position away from the ground electrode and the voltage auxiliary electrode When,
A measurement step of measuring the potential of the ground electrode and the current flowing through the current auxiliary electrode;
A calculation step of calculating a ratio of a potential of the ground electrode measured in the measurement step and a current flowing through the current auxiliary electrode as a ground resistance, and measuring the ground resistance,
The method for measuring ground resistance, wherein the first inductor and the second inductor are arranged at a position away from the ground electrode by a predetermined distance.   The method of claim 1, further comprising a first current confirmation step of adjusting an inductance of the second inductor, a ground area of the current auxiliary electrode, or a frequency of the AC power supply so that a current flows through the current auxiliary electrode. The method for measuring ground resistance according to 1.   The method further comprises a second current confirmation step of adjusting an inductance of the first inductor, a ground area of the voltage auxiliary electrode, or a frequency of the AC power supply so that a current flows through the voltage auxiliary electrode. The method for measuring a ground resistance according to claim 1 or 2. A grounding electrode buried in the earth,
An AC power supply connected to the grounding electrode by a first lead wire;
A voltage auxiliary electrode disposed on the ground at a position away from the ground electrode and connected to the AC power source by a second lead wire;
A current auxiliary electrode disposed on the ground at a position away from the ground electrode and the voltage auxiliary electrode, and connected to the AC power source by a third lead wire,
A measuring device for measuring a ground resistance used for calculating a ratio of a potential of the ground electrode and a current flowing through the current auxiliary electrode as a ground resistance,
The voltage auxiliary electrode is connected to the AC power source via a first inductor,
The current auxiliary electrode is connected to the AC power source via a second inductor,
The first inductor is provided at a position that can be separated from the ground electrode by a predetermined distance or more in the second lead wire or the voltage auxiliary electrode.
The measurement device for measuring ground resistance, wherein the second inductor is provided at a position that can be separated from the ground electrode by a predetermined distance in the third lead wire or the current auxiliary electrode.   The measuring device for measuring ground resistance according to claim 1, wherein an inductance of at least one of the first inductor and the second inductor is variable.   Switch capable of switching the circuit between a state where the AC power source and the voltage auxiliary electrode are connected, and a state where the AC power source and the voltage auxiliary electrode are connected and the AC power source and the current auxiliary electrode are connected The measuring apparatus for measuring the ground resistance according to claim 1, further comprising a measuring device.

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