JPH09329632A - Method for measuring ground resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring ground resistance capable of simply measuring even in a narrow place. SOLUTION: A resistance measuring device 10 capable of frequency sweep is terminated in a fixed or variable impedance, one electrode is connected to the ground pole 1 of an object to be measured through inductance L, and ground resistance is found by calculation on the basis of an impedance value during resonance of a circuit. In addition, the resistance measuring device whose frequency is constant is terminated in variable impedance, the other electrode is connected to the ground pole 1 of the object to be measured through variable inductance, and the ground resistance is found by calculation on the basis of the impedance value during the resonance of the circuit.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for measuring ground resistance.

A conventional method of measuring ground resistance will be described with reference to FIG. In FIG. 1, 1 is a ground electrode, 2 and 3 are auxiliary electrodes, 4, 5 and 6 are lead wires, 7 is a ground resistance meter, E,
P and D are terminals of the ground resistance meter 7. In the conventional measurement method, the auxiliary electrodes 2 and 3 are connected to the ground electrode 1 from 50 m to 100
Drive into the ground at a distance of about m and apply a voltage from the oscillator OSC between electrodes 1 and 3,
Then, the measured voltage V with respect to the applied voltage and the current A at the time of application are measured, and the ground resistance is obtained from the ratio of the two.

[0003]

In such a conventional method, when measuring the ground resistance, it is necessary to drive two auxiliary electrodes apart from the ground electrode. At this time, the ground resistance depends on the position of the auxiliary electrode or the soil,
There is a problem that it is difficult to select a place to obtain an accurate ground resistance. In addition, there is no problem if a large space can be secured, but there is a problem that it is difficult to measure the ground resistance in urban areas or high-rise buildings.

An object of the present invention is to provide a ground resistance measuring method which can be easily measured even in a narrow space.

[0005]

In order to achieve the above object, the ground resistance measuring method of the present invention has a resistance measuring device capable of frequency sweeping, which is terminated with a fixed or variable impedance, and one electrode of which is connected via an inductance. It is characterized in that it is connected to a grounding electrode to be measured and the grounding resistance is calculated by calculation based on the impedance value at the time of resonance of the circuit.

Further, another ground resistance measuring method of the present invention is
Terminate a resistance measuring instrument with a constant frequency with a variable impedance, connect one of its electrodes to the ground electrode of the measurement target via a variable inductance, and calculate the ground resistance based on the impedance value at the circuit resonance. Characterize.

According to the present invention as described above, the ground resistance can be easily calculated by measuring the resonance frequency. An embodiment of the present invention will be described below with reference to the drawings.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment will be described with reference to FIG. In FIG. 2, 1 is a ground electrode, 8 is a variable frequency resistance measuring instrument, and 9 is a measuring cable. Here, r is the terminal resistance, L is the inductance, and C is the capacitance of the earth return circuit. When the frequency characteristic of impedance is measured by such a device, the result as shown in FIG. 3 is obtained. That is,
The impedance Z exhibits the minimum value Zo at the resonance frequency wo.

On the other hand, the equivalent circuit for FIG. 2 is as shown in FIG. In FIG. 4, R represents the ground resistance to be measured. In this case, the impedance Z of the equivalent circuit is given as follows.

[Equation 1]

Where w is the angular frequency. At this time, when the equivalent circuit is resonated, the imaginary part of the equation (1) disappears, and the equation (1) becomes as follows.

[Equation 2]

As a result, regardless of the inductance L and the capacitance C, the target ground resistance R is obtained from the impedance Zo at resonance obtained from the ground resistance measuring device and the terminating resistance r (known) using the equation (2). You can ask.

Next, a second embodiment will be described with reference to FIG. The structure of this embodiment is basically the same as the structure shown in FIG. 2 except that the frequency of the resistance measuring device 10 is constant and the inductance L and the terminating resistance r are variable. When the relationship between the impedance Z and the inductance L is measured by such a device, the result as shown in FIG. 6 is obtained. That is, at the value of the inductance Lo at which the resonance of the LCR circuit occurs, the impedance Z exhibits the minimum value Zo, and the ground resistance R can be obtained from this value and the value of the terminating resistance r using equation (2).

[0013]

As described above, when the ground resistance is measured using the ground resistance measuring method of the present invention, it is not necessary to use an auxiliary electrode as in the conventional case, and therefore the measurement can be easily performed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a conventional ground resistance measuring method.

FIG. 2 is a diagram illustrating a first embodiment of the present invention.

FIG. 3 is a diagram showing an example of frequency characteristics of impedance measured by the measuring method of FIG.

FIG. 4 is a diagram showing an equivalent circuit of the configuration shown in FIG.

FIG. 5 is a diagram illustrating a second embodiment of the present invention.

6 is a diagram showing an example of a relationship between impedance and inductance measured by the measuring method of FIG.

[Explanation of symbols]

 1 Ground electrode 2, 3 Auxiliary electrodes 4, 5, 6 Lead wire 7 Ground resistance meter 8 Frequency variable resistance measuring instrument 9 Measurement cable 10 Resistance measuring instrument E, P, D Ground resistance meter 7 terminal OSC oscillator r Termination resistance L Inductance C Ground return circuit capacity

Claims (2)

[Claims] 1. A frequency sweepable resistance measuring device is terminated with a fixed or variable impedance, one electrode of which is connected to a ground electrode to be measured through an inductance, and calculation is performed based on the impedance value at the time of resonance of the circuit. A method for measuring ground resistance, characterized in that the ground resistance is obtained by. 2. A resistance measuring device having a constant frequency is terminated by a variable impedance, one electrode of which is connected to a ground electrode of a measuring object through a variable inductance, and is grounded by calculation based on an impedance value at the time of resonance of the circuit. A method for measuring ground resistance, characterized by obtaining resistance.