JP2002131349A - Method and device for measuring grounding resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily measure grounding resistance of an individual grounding electrode without separating a grounding conductor from existing equipment or using any auxiliary electrode. SOLUTION: This grounding resistance measurement device is provided with a lead wire 2, in which one end is connected to a grounding conductor 5 connecting the existing equipment 6 to the individual grounding electrode 1 buried in the ground together, a return conductive wire 3, in which one end is opened and arranged for forming capacity coupling with the ground, and a measurement apparatus 4 measuring the grounding resistance of the individual electrode from a voltage ratio measured at a time before/after impression of an alternating current signal when the alternating current signal is impressed between the other end of the lead wire and the other end of the return conductive wire. A circuit exhibiting high impedance in the vicinity of a frequency of the alternating current signal used for measurement of the grounding resistance of the individual grounding electrode while exhibiting low impedance in the vicinity of a commercial frequency is inserted between the connection point in the grounding conductor with one end of the lead wire and the existing equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground resistance measuring method and a ground resistance measuring device for measuring the ground resistance of an individual ground electrode without impairing the function as a ground.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration of a conventional ground resistance measuring apparatus for measuring the ground resistance of a ground electrode without using an auxiliary electrode. In the figure, 1 is a ground electrode buried in the ground, 2
Is a lead wire whose grounding pole is connected to the measuring instrument 4, and 3 is arranged so that one end is open and is capacitively connected to the ground,
The return conductor 4 whose other end is connected to the measuring device 4 is a measuring device for measuring the ground resistance of the ground electrode 1. The ground resistance measuring device includes a lead wire 2, a return conductor 3, and a measuring device 4.

In the conventional grounding resistance measuring device having the above-described configuration, a sine wave signal having a frequency of about several hundred kHz to 2 MHz is generated from the measuring device 4 and the signal is transmitted to the grounding pole 1 via the lead wire 2 and the return conductor 3. At this time, the ground resistance constituted by the measuring system, the lead wire 2 and the return conductor 3
The ground resistance is determined from the impedance of the series and the impedance at the resonance point of the series resonance circuit including the capacitance formed between the return conductor 3 and the ground.

[0004]

In the conventional earth resistance measuring device, it is possible to measure the earth resistance of an independent earth electrode without using an auxiliary electrode. However, when measuring the grounding resistance of individual grounding poles of existing equipment connected to other grounding bodies, the individual grounding resistance must be measured because the applied signal flows to grounding bodies other than the individual grounding poles. Was difficult.

[0005] Therefore, in order to measure the ground resistance of each ground electrode, it is necessary to separate each ground electrode from the existing equipment or the grounding body connected to the existing equipment. The present invention has been made in view of such circumstances, and a grounding device that can easily measure the grounding resistance of an individual grounding electrode without disconnecting a grounding line from existing equipment and without using an auxiliary electrode. It is an object to provide a resistance measuring method and a ground resistance measuring device.

[0006]

In order to achieve the above object, according to the present invention, there is provided a lead wire connected to a ground wire for connecting existing equipment and an individual ground electrode buried in the ground. When an AC signal is applied between one end of the return conductor and the other end of the return lead wire disposed with one end open so as to be capacitively coupled to the ground, the time before and after the AC signal is applied In the grounding resistance measuring method for obtaining the grounding resistance of the individual grounding pole from the voltage ratio measured in the above, the impedance between the connection point of the grounding wire with the other end of the lead wire and the existing equipment, the impedance of the individual equipment It is characterized in that the impedance is set to be high near the frequency of the AC signal used for measuring the ground resistance of the ground pole, and to be low near the commercial frequency to measure the ground resistance.

According to a second aspect of the present invention, a lead wire having one end connected to a ground wire connecting an existing facility and an individual ground electrode buried in the ground, and a ground wire having one end opened. A return conductor arranged to be capacitively coupled to the
When an AC signal is applied between the other end of the lead wire and the other end of the return conductor, a measurement is performed to measure the ground resistance of the individual ground electrode from a voltage ratio measured before and after the application of the AC signal. Means for measuring the grounding resistance of the individual grounding pole between the connection point of the grounding line and one end of the lead wire and the existing equipment, near the frequency of the AC signal used for measuring the grounding resistance of the individual grounding pole. It is characterized in that a circuit that becomes impedance and has low impedance near the commercial frequency is inserted.

[0008] Further, the invention described in claim 3 is based on claim 2.
In the grounding resistance measuring device according to the above, the circuit is a cylindrical body formed of a ferromagnetic material attached between the connection point of the grounding wire and one end of the lead wire and the existing equipment. Features.

The invention described in claim 4 is the same as the invention described in claim 2.
3. The grounding resistance measuring device according to item 1, wherein the circuit is an inductance.

The invention described in claim 5 is the same as the claim 2.
Wherein the circuit is a parallel circuit in which an inductance and a capacitance are connected in parallel.

According to the ground resistance measuring method of the present invention,
One end of a lead wire connected to a ground wire connecting an existing facility and an individual ground electrode buried in the ground is arranged with one end open so as to be capacitively coupled to the ground. When an AC signal is applied between the other end of the return conductor,
In the grounding resistance measuring method for obtaining the grounding resistance of the individual grounding pole from the voltage ratio measured before and after the application of the AC signal, a connection point between the ground wire and the other end of the lead wire, The impedance between the individual ground poles is set to a high impedance near the frequency of the AC signal used to measure the ground resistance of the individual ground pole, and the impedance is set to a low impedance near the commercial frequency. And the individual ground electrodes are electrically separated with high impedance. At this time, since the impedance is low at the commercial frequency, the function as the security ground is not affected. Therefore, the ground resistance of the individual ground electrode can be measured without disconnecting the ground line from the existing equipment and without using the auxiliary electrode.

According to the grounding resistance measuring device according to the present invention,
A measurement signal (AC signal) is applied to the ground electrode via the lead wire and the return conductor, and the ground resistance of the individual ground electrode can be determined from the voltage ratio between the signal application terminals of the measuring instrument before and after the application of the measurement signal. it can. At this time, the impedance becomes high near the frequency of the AC signal used for measuring the ground resistance of the individual ground electrode between the connection point of the ground wire and the lead wire and the existing equipment, and becomes low impedance near the commercial frequency. By inserting the circuit, the signal does not flow to the existing equipment via the ground line, and thus the applied signal flows to the ground electrode.

However, since the circuit has a low impedance with respect to the frequency of the commercial power supply, there is no influence on the function as a ground. Therefore, the ground resistance of the individual ground electrode can be measured without disconnecting the ground line from the existing equipment and without using the auxiliary electrode.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, the ground resistance measuring apparatus according to the first to fourth embodiments of the present invention includes an existing facility and one end of a lead wire connected to a ground wire connecting an individual ground electrode buried in the ground, When an AC signal was applied between the other end of the return conductor disposed with one end open so as to be capacitively coupled to the ground, the measurement was performed before and after the AC signal was applied. In the grounding resistance measuring method for obtaining the grounding resistance of the individual grounding pole from a voltage ratio, an impedance between a connection point of the grounding line with the other end of the lead wire and the existing equipment is set to the grounding of the individual grounding pole. A device for implementing a ground resistance measuring method, characterized in that the impedance is measured at a high impedance near the frequency of the AC signal used for measuring the resistance and at a low impedance near the commercial frequency, and the ground resistance is measured. That.

<First Embodiment> FIG. 1 shows a configuration of a ground resistance measuring apparatus according to a first embodiment of the present invention. In the figure, a ground resistance measuring device according to the present embodiment includes a lead wire 2 having one end connected to a ground wire 5 connecting an existing facility 6 and an individual ground electrode 1 buried in the ground, When an AC signal is applied between an open end of the return lead wire 3 disposed so as to be capacitively coupled to the ground and the other end of the lead wire 2 and the other end of the return lead wire 3, the AC signal And a measuring device 4 for measuring the ground resistance of the individual ground electrode 1 from the voltage ratio measured before and after the application.

Further, the earth resistance measuring apparatus according to the present embodiment is used for measuring the earth resistance of the individual earth pole 1 between the connection point between the ground wire 5 and one end of the lead wire 2 and the existing equipment 6. A circuit 8 having a high impedance near the frequency of the AC signal and a low impedance near the commercial frequency is inserted. 7 is another grounding body connected to the existing equipment.

In the above configuration, since the circuit 8 has a high impedance in the frequency band of the AC signal for measuring the ground resistance of the individual ground pole 1, that is, in the measurement frequency band, the individual ground pole 1 and the existing equipment have a high impedance. (However, since the impedance is low at the commercial frequency, it does not affect the function as the safety ground). Therefore, only the ground resistance value of the individual ground electrode 1 can be evaluated in the measurement of the ground resistance of the individual ground electrode 1. As described above, according to the present embodiment, the ground resistance of the individual ground electrode can be measured without disconnecting the ground line from the existing equipment and without using the auxiliary electrode.

<Second Embodiment> FIG. 2 shows a configuration of a ground resistance measuring apparatus according to a second embodiment of the present invention. The ground resistance measuring apparatus according to the present embodiment differs from the ground resistance measuring apparatus according to the first embodiment in configuration in that the ground resistance measuring apparatus is connected to one end of the lead wire 2 in the ground line 5 instead of the circuit 8 in FIG. This is the point that a cylindrical body 9 made of a ferromagnetic material is mounted between the connection point and the existing equipment, and the other configuration is the same as that of the first embodiment, and thus the duplicated description will be omitted.

In the grounding resistance measuring apparatus according to the present embodiment having the above-described configuration, the cylindrical body 9 formed of a ferromagnetic material inserted into the grounding line 5 has the same characteristics as the circuit 8 and has the individual grounding pole. 1 has a characteristic that the impedance becomes high at the measurement frequency of the ground resistance and becomes low at the commercial frequency.

Therefore, in the measurement frequency band, the cylindrical body 9 made of a ferromagnetic material has a high impedance, so that the individual grounding pole 1 and the existing equipment 6 are electrically separated (however, at the commercial frequency, Since the cylindrical body 9 formed of a ferromagnetic material has low impedance, it does not affect the function as a security ground.) Therefore, only the ground resistance value of the ground electrode can be evaluated in the ground resistance measurement. As described above, according to the present embodiment, similarly to the first embodiment, it is possible to measure the ground resistance of the individual ground electrode without disconnecting the ground line from the existing equipment and without using the auxiliary electrode. it can.

<Third Embodiment> FIG. 3 shows a configuration of a ground resistance measuring apparatus according to a third embodiment of the present invention. The ground resistance measuring apparatus according to the present embodiment differs from the ground resistance measuring apparatus according to the first embodiment in configuration in the circuit 8 in FIG.
Instead of this, an inductance 10 having the same characteristics as the circuit 8 exhibiting high impedance characteristics at the measurement frequency is inserted into the ground line 5, and the other configuration is the same as that of the first embodiment. Duplicate description will be omitted. At this time, the ground line 5 in the section where the inductance 10 is inserted is once disconnected, but there is no problem in the function as the security ground.

In the ground resistance measuring apparatus according to the present embodiment having the above-described configuration, since the inductance 10 has a high impedance in the measurement frequency band, the individual ground electrode 1 and the existing equipment 6 are electrically separated ( However, since the inductance 10 has a low impedance at a commercial frequency, the inductance 10 does not affect the function as a security ground.) For this reason, the individual ground electrode 1
Can be evaluated only. As described above, according to the present embodiment, similarly to the first embodiment, it is possible to measure the ground resistance of the individual ground electrode without disconnecting the ground line from the existing equipment and without using the auxiliary electrode. it can.

<Fourth Embodiment> FIG. 4 shows the configuration of a ground resistance measuring apparatus according to a fourth embodiment of the present invention. The ground resistance measuring apparatus according to the present embodiment differs from the ground resistance measuring apparatus according to the first embodiment in configuration in the circuit 8 in FIG.
Instead of this, a parallel circuit 11 in which an inductance and a capacitance having characteristics similar to those of the circuit 8 showing high impedance characteristics at the measurement frequency are connected in parallel to the ground line 5 is inserted. Are the same as in the first embodiment, and a duplicate description will be omitted. At this time, the ground line 5 in the section where the parallel circuit 11 is inserted is once disconnected, but there is no problem in the function as the security ground.

In the ground resistance measuring apparatus according to the present embodiment having the above configuration, the parallel circuit 11 in which the inductance and the capacitance are connected in parallel has a high impedance in the measurement frequency band. The equipment 6 is electrically isolated (however, at commercial frequency,
Since the parallel circuit 11 has a low impedance, it does not affect the function as a security ground). Therefore, only the ground resistance value of the individual ground electrode 1 can be evaluated in the ground resistance measurement. Thus, according to the present embodiment,
As in the first embodiment, the ground resistance of the individual ground electrode can be measured without disconnecting the ground line from the existing equipment and without using an auxiliary electrode.

[0025]

As described above, according to the ground resistance measuring method of the present invention, one end of a lead wire connected to a ground wire connecting existing equipment and an individual ground electrode buried in the ground. When an AC signal is applied between the other end of the return lead wire disposed with one end open so as to be capacitively coupled to the ground, measurement is performed before and after the AC signal is applied. The ground resistance of the individual ground pole from the voltage ratio obtained, the impedance between the connection point of the ground wire and the other end of the lead wire and the existing equipment, the individual ground pole The ground resistance is measured at a high impedance near the frequency of the AC signal used to measure the ground resistance of the AC signal, and at a low impedance near the commercial frequency. There are electrically isolated by high impedance. At this time, since the impedance is low at the commercial frequency, the function as the security ground is not affected. Therefore, the ground resistance of the individual ground electrode can be measured without disconnecting the ground line from the existing equipment and without using the auxiliary electrode.

Further, according to the ground resistance measuring apparatus of the present invention, a lead wire having one end connected to a ground wire connecting an existing facility and an individual ground electrode buried in the ground, When an AC signal is applied between the other end of the lead wire and the other end of the return lead wire, the return lead wire is disposed so as to be capacitively coupled therebetween. A measuring means for measuring a ground resistance of the individual ground electrode from the measured voltage ratio, wherein the individual equipment is provided between a connection point of the ground wire with one end of the lead wire and the existing equipment. Since a circuit with high impedance near the frequency of the AC signal used for measuring the grounding resistance of the grounding pole and low impedance near the commercial frequency was inserted, do not disconnect the grounding line from the existing equipment. , Without using the auxiliary electrode, it is possible to measure the ground resistance of individual earth electrode.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a grounding resistance measuring device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a grounding resistance measuring device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a grounding resistance measuring device according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a grounding resistance measuring device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional ground resistance measuring device.

[Description of Signs] 1 Individual grounding pole 2 Lead wire 3 Return wire 4 Measuring instrument 5 Ground wire 6 Existing equipment 7 Other grounding body 8 High impedance circuit 9 Cylindrical body formed of ferromagnetic material 10 Inductance 11 Inductance and electrostatic Capacity parallel circuit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Mitsuo Hattori Inventor F-term (reference) 2G028 AA01 BC06 CG02 DH05 FK09 HN02 MS01 in Nippon Telegraph and Telephone Corporation 3-9-1-2 Nishishinjuku, Shinjuku-ku, Tokyo

Claims (5)

[Claims] 1. One end of a lead wire connected to a ground wire connecting an existing facility and an individual ground electrode buried in the ground,
When an AC signal was applied between the other end of the return conductor disposed with one end open so as to be capacitively coupled to the ground, the measurement was performed before and after the AC signal was applied. In a ground resistance measuring method for obtaining a ground resistance of the individual ground pole from a voltage ratio, a connection point of the ground wire with the other end of the lead wire;
Impedance between the existing equipment, high impedance near the frequency of the AC signal used to measure the ground resistance of the individual grounding pole, high impedance near the commercial frequency, to measure the ground resistance by low impedance. Ground resistance measurement method. 2. A lead wire having one end connected to a ground wire connecting an existing facility and an individual ground electrode buried in the ground,
A return conductor, one end of which is open and disposed so as to be capacitively coupled to the ground, and an AC signal applied between the other end of the lead wire and the other end of the return conductor. A ground resistance measuring device having measuring means for measuring a ground resistance of the individual ground electrode from a voltage ratio measured before and after signal application, wherein a connection point of the ground wire with one end of the lead wire and the existing equipment A circuit having a high impedance near the frequency of the AC signal used for measuring the ground resistance of the individual ground electrode and a low impedance near the commercial frequency. 3. The circuit according to claim 2, wherein the circuit is a ferromagnetic cylinder formed between the connection point of the ground wire and one end of the lead wire and the existing equipment. Item 3. The earth resistance measuring device according to Item 2. 4. The ground resistance measuring apparatus according to claim 2, wherein the circuit is an inductance. 5. The ground resistance measuring device according to claim 2, wherein the circuit is a parallel circuit in which an inductance and a capacitance are connected in parallel.