JPH06213945A - Distribution line ground resistance measuring device and distribution line ground resistance measuring method - Google Patents

Abstract

(57) [Summary] [Purpose] When measuring the ground resistance of pole transformers of distribution lines, it is not necessary to destroy the pavement on the ground surface, and the auxiliary pole can be grounded easily. [Structure] The current auxiliary electrode 10 and the potential auxiliary electrode 11 are sheet electrodes, and the capacitance C and the oscillation frequency of the power supply 7 are f
Then, the impedance Z of both auxiliary electrodes 10 and 11 is obtained, and the current I to be supplied from the power supply 7 is determined by the relationship between the performance of the power supply 7 and the impedance Z. Thereby, the oscillation voltage Vo of the power supply 7 is set, and the voltage V applied to the potential auxiliary pole 11 is measured by the voltmeter 9. The ground resistance R is measured as R = V / I.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distribution line ground resistance measuring device and a distribution line ground resistance measuring method.

[0002]

2. Description of the Related Art As is well known, the ground resistance has one ground electrode, and when the ground current I (A) flows into this, the potential of the ground electrode becomes higher by V (V) than the surrounding ground. The ground resistance R (Ω) is defined as the ratio V / I of the potential rise value and the ground current at this time. The potential drop method is currently most commonly used for the apparatus and method for measuring the ground resistance.

By the way, when measuring the grounding resistance of a pole transformer of a distribution line, various methods of potential drop method are generally used. In any case, however, the grounding resistance measuring instrument currently in practical use is used. Requires a current and potential auxiliary pole due to the measurement principle. That is, as shown in FIG. 3, one ground electrode 4 is connected to the ground wire 3 of the pole transformer 2 to which the distribution line 1 is connected, and the current auxiliary pole 5 and the potential auxiliary electrode 6 are connected in parallel to the ground wire 3. , Both auxiliary electrodes 5 and 6 are installed at an appropriate distance from the ground electrode 4, and the power supply 7 and the ammeter 8 are connected between the ground electrode 4 and the current auxiliary electrode 5, while the ground electrode and the potential auxiliary electrode 6 are connected. A voltmeter 9 is connected between the and. Then, a current is made to flow from the power supply 7 to the ground electrode 4 at an appropriate oscillation voltage Vo, the current I (A) is measured by the ammeter 8, and the drop potential V (V) between the ground electrode 4 and the potential auxiliary pole is measured by the voltmeter. Measured according to 9. The ratio V / I of the drop potential and the current becomes the ground resistance R (Ω) according to the definition already described.

[0004]

By the way, the grounding wire 3 of the pole transformer 2 may be buried at the same time when the utility pole is erected, but the auxiliary pole cannot be permanently installed and should be buried for each measurement. become. For this reason, in the present situation where the pavement of the urban area has advanced, in order to ground the auxiliary poles 5 and 6, the asphalt layer provided on the ground surface is pierced each time measurement is performed. However, if such an auxiliary pole must be set for each measurement, it will inevitably involve very troublesome destruction of the asphalt layer and restoration work for the current state. For this reason, the above-mentioned ground resistance measurement is unrealistic, especially in urban areas.

The present invention has been made in view of such conventional problems, and provides an apparatus and method capable of grounding an auxiliary electrode without destroying pavement such as asphalt and easily measuring ground resistance. The purpose is to provide.

[0006]

In order to achieve the above object, a distribution line grounding resistance measuring device according to the present invention has one grounding electrode connected to a grounding line of a distribution line and the above grounding line connected to the grounding line. From a current auxiliary electrode and a potential auxiliary electrode that are appropriately separated from the electrode, a power supply and an ammeter connected between the ground electrode and the current auxiliary electrode, and a voltmeter connected between the ground electrode and the potential auxiliary electrode. In the distribution line ground resistance measuring device, a current is supplied to the ground electrode by the power source at an appropriate oscillation voltage, and the ground resistance is measured by the current value and the potential drop value between the ground electrode and the potential auxiliary pole. The current auxiliary electrode and the potential auxiliary electrode have a sheet-like electrode having an appropriate area.

In order to achieve the above object, the distribution line grounding resistance measuring method according to the present invention connects a pair of ground electrodes to the grounding line of the distribution line, one of which is a current auxiliary electrode and the other of which is a potential auxiliary electrode. A pair of sheet-shaped electrodes having an appropriate area are connected to the ground wire and are installed at an appropriate distance from the ground electrode, and a power source and an ammeter are connected between the ground electrode and the current auxiliary electrode, and the ground electrode is connected. A voltmeter is connected between the potential auxiliary poles, a current is applied to the ground electrode by the power supply at an appropriate oscillation voltage, and the ground resistance is measured by the current value and the potential drop value between the ground electrode and the potential auxiliary pole. It has a configuration designed to do so.

Next, the principle of the apparatus and method of the present invention will be described with reference to FIG. Note that, in FIG. 2, the same reference numerals are given to the portions common to the respective constituent elements in FIG. In the figure, 10 is a current auxiliary electrode, 11 is a potential auxiliary electrode, and both auxiliary electrodes 10 and 11 are sheet electrodes having the same area. Both auxiliary poles 1
Area S of 0 and 11, vacuum permittivity εo, thickness of asphalt layer on the ground surface d, relative permittivity of asphalt εs
Then, the capacitance C when both auxiliary poles 10 and 11 are on the ground surface is

## EQU1 ## It is expressed as C = S.εo.εs / d (F). When the impedance Z of both auxiliary poles 10 and 11 is calculated with the oscillation frequency of the power source 7 as f,

## EQU2 ## It is expressed as Z = 1 / 2.pi.fC (Ω). Then, the current I that should flow from the power source 7
If the oscillation voltage Vo of the power supply 7 is set and the voltage applied to the potential auxiliary pole 11 is measured by the voltmeter 9,

## EQU00003 ## The ground resistance is measured by Z = V / I. For example, if the oscillator frequency f is several hundred kHz, the impedance Z of both auxiliary poles 10 and 11 will be several hundred Ω to several kΩ depending on their areas, and if the oscillation voltage Vo of the power supply 7 is several hundred V, several Ten meters
A current I of A to several hundred mA can be passed through the circuit, and sufficient ground resistance can be measured.

[0009]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram conceptually showing one embodiment of the distribution line grounding resistance measuring device according to the present invention. Note that parts common to those of the conventional example of FIG. 3 and the principle explanatory diagram of FIG.

The current auxiliary pole 10 and the potential auxiliary pole 11 are vertically arranged in 1
A sheet-like electrode having m, a width of 5 m, and an area S of 5 m ² .
Vacuum dielectric constant εo a 8.86 × 10- ^12, the thickness d of 5 × 10 ^-2 m asphalt layer, the dielectric constant of asphalt εs
Is 1, the capacitance C when both auxiliary poles 10 and 11 are on the ground surface is

## EQU4 ## C = 8.86 × 10 ^-10 (F) = 886 (pF). Considering this to be about 1000 pF, when the oscillation frequency f of the power supply 7 is set to 100 kHz and the impedance Z of both auxiliary poles 10 and 11 is calculated,

## EQU00005 ## Z = 1.6.times.10.sup.- ³ (.OMEGA.) = 1.6 (k.OMEGA.). If the current I to be supplied from the power supply 7 is 0.1 (A), the oscillation voltage Vo of the power supply 7 is

## EQU6 ## Vo> 0.1 × 1.6 × 10 ³ = 160 (V). Then, if the voltage V applied to the potential auxiliary pole 11 is measured by the voltmeter 9, the ground resistance Z is measured by the above-mentioned formula 3.

Here, what should be taken into consideration in the actual measurement of the ground resistance is that the capacitance C of the distribution line 1 enters in parallel as shown in FIG. Further, since the voltage / current circuit has a high impedance, the voltage / current indicator may be distorted due to radio waves or transmission current. As a known measure, a voltmeter 9 or an ammeter 8 may be connected via a filter or a synchronous rectifier so as to remove a current or a voltage that causes an error.

[0012]

Since the distribution line ground resistance measuring device and the distribution line ground resistance measuring method according to the present invention have been described above, they are formed on the ground surface when measuring the ground resistance of the pole transformer of the distribution line. There is no need to destroy the pavement such as asphalt, and the auxiliary pole can be grounded easily.
In addition to being able to measure sufficient ground resistance, there is no need to recover the current state due to the removal of the auxiliary electrode, so there is an effect that work time and work cost can be significantly saved.

[Brief description of drawings]

FIG. 1 is a circuit diagram conceptually showing one embodiment of a distribution line grounding resistance measuring device according to the present invention.

FIG. 2 is a circuit diagram showing the principle of a distribution line ground resistance measuring device and a distribution line ground resistance measuring method according to the present invention.

FIG. 3 is a circuit diagram conceptually showing an example of a conventional distribution line grounding resistance measuring device.

[Explanation of symbols]

 1 distribution line 2 pole transformer 3 ground wire 4 ground electrode 5 current auxiliary pole 6 potential auxiliary pole 7 power supply 8 ammeter 9 voltmeter 10 current auxiliary pole 11 potential auxiliary pole

Claims (2)

[Claims] 1. A ground electrode connected to a ground line of a distribution line, a current auxiliary electrode and a potential auxiliary electrode connected to the ground line and appropriately separated from the ground electrode, the ground electrode and the current auxiliary. It consists of a power supply and an ammeter connected between the poles, and a voltmeter connected between the ground electrode and the potential auxiliary pole, and a current is passed to the ground electrode by the power supply with an appropriate oscillation voltage, and the current value and the Distribution line for measuring the ground resistance by the potential drop value between the ground electrode and the potential auxiliary electrode In the ground resistance measuring device, the current auxiliary electrode and the potential auxiliary electrode are sheet electrodes having appropriate areas. Ground resistance measuring device. 2. A pair of sheet-shaped electrodes, each having a proper area in which a pair of ground electrodes are connected to a ground wire of a distribution line, one of which serves as a current auxiliary electrode and the other of which serves as a potential auxiliary electrode, and the ground wire is connected to the ground wire. It is installed at an appropriate distance from the ground electrode, a power source and an ammeter are connected between the ground electrode and the current auxiliary pole, a voltmeter is connected between the ground electrode and the potential auxiliary pole, and the above is applied at an appropriate oscillation voltage. A distribution line ground resistance measuring method, in which a current is caused to flow to the ground electrode by a power supply, and the ground resistance is measured based on the current value and the potential drop value between the ground electrode and the potential auxiliary electrode.