KR102593291B1 - A ground resistance measurement system on energized line using ground potential of grounding electrode and the method thereof - Google Patents

Abstract

Measure the grounding resistance of electrical equipment using the ground potential of the grounding electrode, measure the GP value and the grounding current flowing through the grounding electrode while the electrical equipment is in operation, and apply a correction coefficient to these to correct the grounding resistance. It relates to a system and method for measuring ground resistance in a live state using a potential rise of a ground electrode, comprising: a ground electrode (11) buried in the ground; In order to measure ground resistance, a measuring ground electrode 16 serves as an infinitely long-distance reference potential electrode; A current sensor unit 50 that measures ground current on the ground wire 80; a voltage measuring unit that measures the voltage between the voltage measuring point (A) on the ground electrode and the voltage measuring point (B) of the measuring potential electrode serving as a reference potential; And, a configuration including an arithmetic output unit that receives the ground potential value and the ground current and calculates ground resistance is provided.
By using the system and method described above, the potential rise value of the grounding electrode is measured in a live state and corrected with a correction coefficient, so that the grounding system (grounding electrode) is operated (with power supplied) without being separated from the electrical equipment. Ground resistance can be measured even in small spaces, and in particular, it can be measured in narrow spaces without any distance restrictions on the reference potential point.

Description

{ A ground resistance measurement system on energized line using ground potential of grounding electrode and the method thereof }

The present invention measures the grounding resistance of electrical equipment by using the potential rise (Ground potential: GP or Earth potential: EP) of the ground electrode in a live state, and the potential rise of the ground electrode and the ground electrode while the electric equipment is in operation. Ground resistance measurement in a live state using the potential rise of the ground electrode, which measures the ground current flowing through the ground electrode, measures the potential rise of the ground electrode at a close distance, and applies a correction coefficient to correct the potential rise of the ground electrode. It relates to systems and methods.

Generally, grounding work is carried out in electrical facilities to prevent electric shock accidents to people and animals and disasters in power facilities. However, if the grounding resistance exceeds the specified value due to aging of the grounding point, etc., there is a risk of a safety accident, so the grounding resistance of electrical equipment must be measured regularly. In particular, the work of measuring the grounding resistance of the grounding system involves confirming the actual grounding resistance of the grounding conductor connected to the ground after construction, verifying the grounding resistance calculated by formula at the design stage, and the increase in ground potential of the grounding conductor and the change in ground potential. This is carried out to confirm, confirm the adequacy of grounding resistance for lightning protection, and confirm the results of grounding design for the protection of people and animals. In addition, grounding resistance measurement work is also performed to check the function of the grounding system while it is in operation (also called pressurized or live wire, meaning in a voltage-applied state).

At this time, when trying to measure the ground resistance to the ground installed in the enclosure of an electric device such as an electric motor installed in any factory or building, the method of using a potentiometer-type ground resistance meter using the three-pole method (or the potential drop method) is used. [Patent Documents 1, 2, 3]. The potential drop method is a method used to measure the grounding resistance of large-scale grounding electrodes (integrated grounding systems) such as substations and industrial facilities, but in order to apply it, the following conditions must be satisfied.

First, in order to obtain accurate measurements of the grounding resistance of the grounding electrode during operation, the grounding electrode must be separated from the equipment it protects. Therefore, there is currently no accurately established method for measuring the grounding resistance of the grounding system in an operating (pressurized) state. In addition, measurements must be made with a distance of at least 5 times the size of the ground electrode between the ground electrode to be measured and the current auxiliary electrode (Current Probe).

In addition, the current and potential must be measured while changing the position of the potential auxiliary electrode (Potential Probe) between the ground electrode to be measured and the current auxiliary electrode (Current Probe), and the ground resistance must be converted using Ohm's law. In addition, current in a limited frequency band supplied from the ground resistance measurement equipment is supplied, and only the voltage in that frequency band is measured to convert the ground resistance from Ohm's law. At this time, the current supplied from the measuring equipment affects only a limited part of the integrated grounding system, so it is difficult to accurately measure the grounding resistance of the integrated grounding system.

In particular, the conditions for measuring the grounding resistance of a large-scale grounding electrode (integrated grounding system) are difficult to satisfy for the following reasons.

First, the equipment to be protected cannot be separated from the ground electrode in order to measure ground resistance during operation. Separating the grounding electrode from the equipment to be protected during operation does not meet the purpose of installing the grounding system of the equipment to be protected. Therefore, it is necessary to measure the grounding resistance of the grounding system in an operating (pressurized) state without separating the equipment to be protected from the grounding system.

In addition, a method of measuring the grounding resistance of the grounding system is needed in limited areas such as urban areas and underground sections where it is impossible to secure a distance of at least 5 times the size of the grounding electrode between the grounding electrode to be measured and the current auxiliary electrode (Current Probe). do.

In addition, the integrated grounding system in operation has various waveforms such as various frequency bands and harmonics, so in order to accurately measure ground resistance, the current and voltage in all frequency bands appearing in the integrated grounding system in operation must be measured and calculated from Ohm's law. A measurement method based on the principle of converting ground resistance is needed.

Korean Patent Publication No. 10-0402062 (announced on October 17, 2003) Korean Patent Publication No. 10-1061447 (announced on September 2, 2011) Korean Patent Publication No. 10-0918515 (announced on September 24, 2009)

The purpose of the present invention is to solve the problems described above, and measure the grounding resistance of electrical equipment by using the potential rise (Ground potential: GP or Earth potential: EP) of the ground electrode in a live state. A grounding device that measures the potential rise of the grounding electrode and the grounding current flowing through the grounding electrode while in operation, measures the potential rise of the grounding electrode at a close distance, and applies a correction coefficient to these to correct the potential rise of the grounding electrode. To provide a system and method for measuring ground resistance in a live state using the potential rise of electrodes.

In order to achieve the above object, the present invention relates to a grounding resistance measurement system in a live wire state using the ground potential of the grounding electrode, where the operating protection device or the neutral point of the power system is connected to the grounding electrode buried in the ground through a grounding wire. A current sensor unit that measures the ground current before the ground to measure the ground resistance of the ground electrode in the operating state when installed; a voltage measuring unit that measures a potential rise value between the ground electrode and an infinitely distant reference potential point; It is characterized by comprising an arithmetic output unit that receives the ground potential value of the ground electrode and the ground current and calculates ground resistance.

In addition, the present invention relates to a system for measuring ground resistance in a live state using the ground potential of a ground electrode, comprising: a ground electrode (11) buried in the ground; In order to measure ground resistance, a measuring ground electrode 16 serves as an infinitely long-distance reference potential electrode; A current sensor unit 50 that measures ground current on the ground wire 80; A voltage measurement unit that measures the voltage between the voltage measurement point (A) on the ground electrode and the infinite origin voltage measurement point; and an arithmetic output unit that receives the ground potential value and the ground current and calculates ground resistance.

In addition, the present invention provides a ground resistance measurement system in a live wire state using the ground potential of the ground electrode, wherein the calculation output unit calculates the ground resistance using the ground current and the ground potential value of the ground electrode, In the process of measuring the ground potential, it is characterized by correction using a correction coefficient when measuring at a short distance rather than at an infinitely distant reference potential point.

The present invention refers to the point “B” shown in Figure 2, which is at the same potential as the measuring potential electrode that serves as a reference potential rather than an infinitely distant reference potential point in the process of measuring the ground potential of the ground electrode. The “point” is not limited to this, and any point that is at the same potential as the measurement potential electrode can be referred to as the “B” point. Hereinafter, this is referred to as the “voltage measurement point (B) of the measurement potential electrode that serves as the reference potential.”

In addition, the present invention relates to a grounding resistance measurement system in a live wire state using the ground potential of a grounding electrode, wherein the calculation output unit measures (a) the installation size of the grounding electrode and serves as a reference potential electrode at an infinite distance. A step of inputting the installation distance of the ground electrode; (b) measuring the ground current of the ground electrode and the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential and receiving the measured value; (c) calculating a correction coefficient; And, (d) calculating the ground resistance by reflecting the calibration coefficient.

In addition, the present invention is a grounding resistance measurement system in a live state using the ground potential of the grounding electrode, and in step (c), the correction coefficient C _cal (ρ,x) is calculated by the following equation 1: do.

[Formula 1]

Here, a and x are the installation radius of the ground electrode and the distance between the measurement ground electrode that serves as a reference potential electrode at an infinite distance from the center of the ground electrode, respectively.

In addition, the present invention is characterized in that in the grounding resistance measurement system in a live state using the ground potential of the grounding electrode, in step (d), the grounding resistance is calculated using the following equation 2.

[Formula 2]

,

Here, V _M (ρ,x) represents the measured voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential, and I _g represents the measured ground current. indicates.

In addition, the present invention provides a ground resistance measurement system in a live wire state using the ground potential of a ground electrode, wherein the calculation output unit includes an electrode size input unit that receives an installation size of the ground electrode; An inter-electrode distance input unit that receives the distance between the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as the reference potential; A voltage input unit that receives the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential; a current input unit that receives a current value of the ground current of each ground line; a calibration coefficient calculation unit that calculates a calibration coefficient using the size of the ground electrode and the distance between the electrodes; and a ground resistance calculation unit that calculates ground resistance using the voltage, current value, and correction coefficient.

In addition, the present invention is characterized in that in the ground resistance measurement system in a live wire state using the ground potential of the ground electrode, the ground resistance calculation unit calculates the ground resistance R _g according to the following equation 3.

[Formula 3]

However, C _cal (ρ,x) is the calibration coefficient, and V _M (ρ,x) is the measured voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential. value, and I _g is the ground current value.

In addition, the present invention relates to a method of measuring ground resistance in a live wire state using the ground potential of the ground electrode through a ground electrode for grounding electrical equipment and a measurement ground electrode that serves as a reference potential electrode at an infinite distance, (a) receiving the installation size of the ground electrode and the installation distance between the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential; (b) measuring the ground current of the ground electrode and the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential and receiving the measured value; (c) calculating a correction coefficient; And, (d) calculating the ground resistance by reflecting the calibration coefficient.

As described above, according to the system and method for measuring ground resistance in a live state using the ground potential of the ground electrode according to the present invention, the potential rise value of the ground electrode in the live state is measured and corrected with a correction coefficient, thereby Grounding resistance can be measured during operation (with power supplied) without disconnecting the grounding system (grounding electrode) from the equipment. In particular, the effect of being able to measure in a narrow space without limitations on the distance of the reference potential point is obtained. .

1 is a conceptual diagram of a ground resistance measurement system using the ground potential of a ground electrode for implementing the present invention.
2 and 3 are block diagrams of the overall system configuration for implementing the present invention.
Figure 4 is a diagram illustrating determining the maximum horizontal length and maximum vertical length of a ground electrode according to an embodiment of the present invention.
Figure 5 is a diagram showing correction of the measured ground potential when measuring ground resistance through the ground potential of the ground electrode according to an embodiment of the present invention.
Figure 6 is a block diagram of the configuration of an arithmetic output unit according to an embodiment of the present invention.
Figure 7 is a flowchart illustrating the measurement method of the ground resistance measurement system in a live state using the ground potential of the ground electrode according to an embodiment of the present invention.

Hereinafter, specific details for implementing the present invention will be described with reference to the drawings.

In addition, in explaining the present invention, like parts are given the same reference numerals, and repeated description thereof is omitted.

First, Figure 1 shows a conceptual diagram of measuring ground resistance using the ground potential of the ground electrode for implementing the present invention.

As shown in Figure 1, when a grounding current (leakage current, etc.) flows through a grounding wire connected to the grounding electrode buried in the ground in a live state for each purpose such as the neutral point of the system grounding, protective grounding, lightning protection grounding, etc., the grounding electrode Ground potential appears in . At this time, the ground current can be measured through a current sensor, the ground potential between an infinitely distant reference potential point and the ground electrode can be measured, and the ground resistance can be measured according to Ohm's law.

Next, the configuration of the entire system for implementing the present invention will be described with reference to FIGS. 2 and 3. Figure 2 is a grounding system installed with individual ground electrodes, and Figure 3 is a grounding system integrated by a grounding reference.

As shown in FIG. 2, the entire system for implementing the present invention consists of a ground terminal portion 20 consisting of the ground terminal 21 of the electrical equipment 90 buried in the ground, and connected to each ground terminal 21 to connect to the ground. A current sensor unit ( 50), a ground terminal for measurement consisting of a ground conductor such as a wire electrically connecting the ground electrode for measurement (16) and the ground terminal for measurement (41) or the ground electrode for measurement (16) and the ground terminal for measurement (41). (40), and an arithmetic output unit (30) that calculates and outputs ground resistance.

The ground terminal portion 20 is composed of a plurality of ground terminals 21. A plurality of ground terminals 21 are connected by an eastern bus bar 22. In addition, the ground electrode 11 is connected to each ground terminal 21 through a ground wire 80 and is buried in the ground.

In particular, each ground terminal 21 is connected to the eastern bus bar 22, so the potential at that point is the same. That is, each ground terminal 21 of the ground terminal portion 20 serves as one ground terminal.

The ground terminal 21 is composed of a type-specific ground terminal, a reinforced ground terminal, and a new ground terminal. Ground terminals by type are classified according to the type of electrical equipment (90), and are ground terminals according to type, such as type 1, type 2, type 3, and special type 3. The reinforced grounding terminal is a grounding terminal for reinforcing grounding to compensate for the deterioration of the original grounding function. Additionally, the new grounding terminal is a terminal for newly added grounding.

In addition, the ground electrode 21 can be divided into a type of ground electrode, a carbon ground rod for reinforcement, a new ground station for new grounding, etc., depending on the type of the ground terminal 21.

Meanwhile, as shown in FIG. 3, the ground electrodes of each type among the ground electrodes 21 may be configured to be integrated into one mesh-type ground electrode 12.

Additionally, the current sensor unit 50 is composed of a plurality of current sensors 51.

Each current sensor 51 is installed on each ground wire 80 to measure ground current. Preferably, the current sensor 51 is a CT (Current Transformer) sensor, and measures the secondary current by connecting the secondary resistance to the ground line 80. In addition, the current sensor 51 can measure current using a Hall sensor or the like.

Next, the ground terminal unit 40 for measurement is composed of a plurality of ground terminals 41 for measurement. In addition, the ground electrode 16 for measurement is connected to each ground terminal 41 for measurement through a ground wire 80 and is buried in the ground.

In addition, the voltage sensor unit 60 is installed to measure the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as a reference potential. That is, in Figure 2 or 3, the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential is measured. That is, one terminal of the voltage sensor is connected to the voltage measurement point (A) on the ground electrode, and the other terminal is connected to the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential, and the voltage is measured.

In addition, the voltage sensor of the voltage sensor unit 60 measures voltage by connecting to one of the plurality of ground terminals 21 or one measurement point of the ground line 80. Since each ground terminal 21 is connected to the copper bus bar 22 and the potential at each ground terminal is the same, the voltage of the ground terminal portion 20 can be measured by measuring any one voltage.

Next, the calculation output unit 30 receives the measured current or voltage values from each current sensor 51 and the voltage sensor unit 60, calculates the ground resistance, and outputs the result. The specific configuration is described below.

Preferably, the calculation output unit 30 is equipped with a microprocessor, receives the measured ground voltage and ground current by the processor and a pre-installed program, and calculates the ground resistance by correcting the ground resistance.

At this time, in the following method, the distance between voltage measurement point A and voltage measurement point B is x-a. Here, x is the shortest distance between the center of the ground electrode 11 and the measuring ground electrode 16 as shown in FIG. 2.

In the above, a is determined according to the shape and burial distribution of the ground electrode 11 connected to the voltage measurement point A.

In the present invention, a calculates the “ground area”, which is the area where grounding elements such as grounding electrodes 11 of equipment for measuring grounding resistance are installed, and a is the radius with the calculated “grounding area” being the area of a circle.

The reason why the “ground area” is the area of the circle and the radius is set to a is because the ground electrode is hemispherical, as shown in FIG. 4.

Therefore, the grounding area of the ground electrode is the area of the circle multiplied by the maximum horizontal length (A, A1, A2, A3) of the ground electrode and the maximum vertical length (B, B1, B2, B3), calculate r, and calculate this as the area of the circle. Let the ground electrode radius a.

An example of determining the maximum horizontal length (A, A1, A2, A3) and maximum vertical length (B, B1, B2, B3) of the ground electrode according to the type in which the ground electrode is installed is shown in the table in FIG. 4. This example is only an example of the standard for setting the area where the ground electrode is installed, and the installation area of the ground electrode is the maximum horizontal length (A, A1, A2, A3) and maximum vertical length (B, B1, B2) of the ground electrode. , B3) is not limited to the method of calculating r by multiplying the area by the area of a circle and then determining this as the ground electrode radius a, and the present invention is therefore not limited to and interpreted only by the above example method.

Next, a method of measuring ground resistance in a live wire state using an increase in ground potential according to an embodiment of the present invention will be described with reference to FIG. 5.

As shown in Figure 5, in an operating power system, a certain amount of current flows to the ground through the ground line. Because of this, the ground potential decreases as the distance from the ground electrode increases. In other words, the ground potential measured according to the distance between the ground electrode and the infinite origin is called GP (ground potential), and appears as a curve shown in FIG. 5.

In Figure 5, Ig represents the current flowing to the ground through the ground wire. In addition, a is the radius of the ground electrode, which is the distance from the center of the ground electrode to the outermost edge of the ground electrode depending on the shape of the ground electrode. Additionally, x is the shortest distance from the center of the ground electrode to the ground electrode for measurement.

It represents the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential. The corresponding voltage is measured as ground potential (GP) value.

A method of measuring the grounding resistance of an integrated grounding system in operation according to an embodiment of the present invention is roughly as follows.

First, measure the ground potential (GP) value V _GP [V] that appears at the ground electrode of the integrated grounding system under operation and the ground current I _g [A] flowing through the ground electrode.

Next, the grounding resistance (R _g ) of the integrated grounding system is converted to Ohm's Law. In other words, calculate the ground resistance R _g using the following equation 1.

[Equation 1]

Here, V _GP represents the ground potential (GP) value, and I _g represents the ground current at the ground electrode.

However, at this time, the ground potential (GP) appearing on the ground electrode of the integrated grounding system that is being measured is between the ground electrode and the reference potential electrode (Remote Earth Probe), which includes various frequency bands and harmonics generated by the integrated grounding system in operation. It is measured as a voltage value of . Therefore, a reference potential electrode must be installed.

Here, the reference potential electrode is a measuring potential electrode for measuring ground resistance and refers to an electrode located at the infinite origin. Therefore, the reference potential electrode must be installed at an infinite distance (at least 5 times the size of the ground electrode).

However, it is difficult to install the reference potential electrode in limited areas such as urban areas and underground sections. Therefore, the rise in ground potential of the grounding electrode is measured by installing it at a distance that allows installation according to field conditions, and then converted to the value measured at an infinite distance (a distance of at least 5 times the size of the grounding electrode) and corrected. In other words, the rise in ground potential of the grounding electrode is measured by installing it according to field conditions, and converted to a value measured at an infinite distance (at least 5 times the size of the grounding electrode).

Next, the calibration method will be explained.

More specifically, as shown in Figure 5, when the radius of the equivalent hemispherical ground electrode of a ground electrode installed on the ground with a ground resistivity of ρ [Ohm-m] is a [m], the distance x [m] from the center of the ground electrode is The calculated ground potential value V(ρ,x) at a distance of

[Equation 2]

In addition, the calculated value V(ρ,x) (=V _GP ) of the ground potential rise at a distance a from the center of the hemispherical ground electrode is calculated as follows (x≤a).

[Equation 3]

Then, the ground potential measurement value V _M (ρ,x) at a distance x from the ground electrode is defined as follows. In other words, V _M (ρ,x) represents the voltage between the ground electrode and the measurement location.

[Equation 4]

In addition, the ground potential measurement value V _M ( _ρ ,x) at a distance of

At this time, the calibration coefficient (Calibrating Constant) C _cal (ρ,x) for correcting from the measured value V _M (ρ,x) to the ground potential rise V _GP is defined as follows.

[Equation 5]

Here, ρ is reflected in the resistance value measured by the measuring equipment when measuring V _M. That is, V _M (ρ,x) is the resistance value measured by the measuring equipment.

By applying the correction coefficient C _cal (ρ,x) from the measured value V _M (ρ,x), the ground potential rise V _GP is corrected as follows.

[Equation 6]

In addition, the ground potential rise V _GP by applying the correction coefficient C _cal (ρ,x) to the measured value V _M (ρ,x) and the ground current I _g flowing through the measured ground electrode are applied to Ohm's law to create an integrated grounding system. Calculate the ground resistance R _g of .

[Equation 7]

Next, the configuration of the calculation output unit 30 according to an embodiment of the present invention will be described in more detail with reference to FIG. 6.

As shown in Figure 6, the calculation output unit 30 according to an embodiment of the present invention includes an electrode size input unit 31 that receives the installation size of the ground electrode, and an inter-electrode distance that receives the distance between the ground electrode and the measurement electrode. Input unit 32, a voltage input unit 33 that receives the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as the reference potential, and a current input unit that receives the current value of the ground current. (34), a calibration coefficient calculation unit 35 that calculates the calibration coefficient, and a ground resistance calculation unit 36 that calculates the ground resistance.

Additionally, it further includes a first AD converter 33b that converts the input voltage into a digital signal, and a second AD converter 34b that converts the input current into a digital signal. Alternatively, a display unit 37a for displaying ground resistance, etc., a control unit 37b for operating buttons or a touch panel, a communication unit 38 for communication, or a power supply unit 39 for supplying power, etc. It can be configured to include.

First, the electrode size input unit 31 receives the installation size of the ground electrode. The installation size of the ground electrode is input as 2a as the installation diameter of the entire ground electrode. You can receive the radius a directly. In addition, the electrode size input unit 31 receives the maximum horizontal length (A, A1, A2, A3) and maximum vertical length (B, B1, B2, B3) of the ground electrode and calculates the area of the circle by multiplying the installation area of the ground electrode. You can calculate r using the area.

Next, the inter-electrode distance input unit 32 receives the distance between the ground electrode and the measurement electrode. The installation distance of the measuring electrode represents the distance x between the center of the ground electrode and the ground terminal or ground electrode for measurement. Preferably, the distance L between the ground electrode for measurement and the point opposite the ground electrode can be input. At this time, L further includes the installation radius a of the ground electrode, so it is equal to x = L-a.

Next, the voltage input unit 33 receives the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential. The measurement voltage is the voltage measured by the voltage sensor unit 60, and represents the voltage V _M between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential. That is, in FIG. 3, the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as the reference potential is measured and received.

Next, the current input unit 34 receives the current value of the ground current. The ground current I _g is a current value measured by the current sensor unit 50. Preferably, the current value is input from the current sensor 51 installed on each of the ground electrode 21 or the ground wire 80. That is, the currents I ₁ , I ₂ , ..., I _n measured at each current sensor 51 are input.

These can be added up in the correction coefficient calculation unit 35. That is, the current input unit 34 receives current from each current sensor 51, adds up the corresponding currents, and outputs the sum.

Or, as another embodiment, the summed current value may be input from the current input unit 34.

Next, the calibration coefficient calculation unit 35 calculates the calibration coefficient.

In particular, the calibration coefficient calculation unit 35 calculates the calibration coefficient using the installation size (a) of the ground electrode output from the electrode size input unit 31 and the inter-electrode distance (x) output from the inter-electrode distance input unit 32. do.

That is, the correction coefficient is calculated according to Equation 5 above. In Equation 5, a and x represent the installation radius of the ground electrode and the distance between the measurement electrode from the center of the ground electrode, respectively.

Preferably, the correction coefficient calculation unit 35 is composed of a circuit that receives x and a as input and calculates Equation 5, such as x/(x-a).

Next, the ground resistance calculation unit 36 calculates the ground resistance.

In particular, the ground resistance calculation unit 36 calculates the measured voltage (V _M ) output from the voltage input unit 33 or the first AD converter 33b, and the ground current output from the power input unit 34 or the second AD converter 34b. I _g , the ground resistance is calculated using the calibration coefficient output from the calibration coefficient calculation unit 35.

At this time, the ground current I _g is a current value obtained by adding up the currents I ₁ , I ₂ , ..., I _n measured at each current sensor.

In other words, the calibration coefficient is input and used to calculate the ground resistance. Ground resistance is calculated using equations 6 and 7. V _M (ρ,x) in Equation 6 represents the measured voltage, and I _g represents the measured ground current.

In addition, the calibration coefficient C _cal (ρ,x) in Equation 6 is a value previously output from the calibration coefficient calculation unit 35.

In other words, the ground resistance calculation unit 36 is composed of a circuit that receives the measured voltage V _M , the ground current I _g , and the correction coefficient C _cal (ρ,x) and calculates the following equation 8.

[Equation 8]

Next, the first AD converter 33b and the second AD converter 34b are circuits that receive analog values and convert them into digital signals or digital values.

Next, a method of measuring ground resistance performed by the calculation output unit 30 according to an embodiment of the present invention will be described with reference to FIG. 7.

As shown in FIG. 7, the calculation output unit 30 receives the installation size of the ground electrode and the installation distance of the measurement electrode (S10).

As shown in Figure 5, preferably, the installation size of the ground electrode is input as 2a as the installation diameter of the entire ground electrode. You can receive the radius a directly. In addition, the electrode size input unit 31 receives the maximum horizontal length (A, A1, A2, A3) and maximum vertical length (B, B1, B2, B3) of the ground electrode and calculates the area of the circle by multiplying the installation area of the ground electrode. You can calculate r using the area.

In addition, the installation distance of the measuring electrode represents the distance x between the center of the ground electrode and the ground terminal or ground electrode for measurement. Preferably, the distance L between the ground electrode for measurement and the point opposite the ground electrode can be input. At this time, L further includes the installation radius a of the ground electrode, so it is equal to x = L-a.

Next, the calculation output unit 30 measures the ground current of the ground electrode and the voltage between the ground electrode and the measurement electrode and receives the measured value (S20).

The ground current I _g is a current value measured by the current sensor unit 50. Preferably, all current values are input from the current sensors 51 installed on each of the ground electrode 21 or the ground wire 80, and these are added together, or the summed current value is input, and the corresponding current value is calculated as the ground current. do.

In addition, the measurement voltage is the voltage measured by the voltage sensor unit 60, and represents the voltage V _M between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as the reference potential.

Next, the calculation output unit 30 calculates the correction coefficient (S30). According to Equation 5, the correction coefficient is calculated. In Equation 5, a and x represent the installation radius of the ground electrode and the distance between the measurement electrode from the center of the ground electrode, respectively.

Next, the calculation output unit 30 calculates the ground resistance by reflecting the calibration coefficient (S40). Ground resistance is calculated using equations 6 and 7. V _M (ρ,x) in Equation 6 represents the measured voltage, and I _g represents the measured ground current.

Above, the invention made by the present inventor has been described in detail based on examples, but the present invention is not limited to the examples and, of course, can be changed in various ways without departing from the gist of the invention.

11: ground electrode 12: mesh type ground electrode
16: Ground electrode for measurement
20: ground terminal 21: ground terminal
22: Long bus bar
30: calculation output unit 31: electrode size input unit
32: Inter-electrode distance input unit 33: Voltage input unit
34: current input unit 33b: first AD converter
34b: second AD converter 35: correction coefficient calculation unit
36: Ground resistance calculation unit
37a: display unit 37b: control unit
38: communication unit 39: power supply unit
40: Ground terminal for measurement 41: Ground terminal for measurement
50: current sensor unit 51: current sensor
60: voltage measuring unit 80: ground wire
90: Electrical equipment
A: Voltage measurement point on ground electrode
B: Voltage measurement point of the measurement potential electrode that serves as the reference potential

Claims (8)

delete delete delete In the ground resistance measurement system in a live state using the ground potential of the ground electrode,
A ground electrode (11) buried in the ground;
In order to measure ground resistance, a measuring ground electrode 16 serves as an infinitely long-distance reference potential electrode;
A current sensor unit 50 that measures the ground current on the ground wire 80 connecting the ground electrode 11;
a voltage measuring unit that measures the voltage between the voltage measuring point (A) on the ground electrode and the voltage measuring point (B) of the measuring potential electrode serving as a reference potential; and,
Comprising an arithmetic output unit that receives the ground potential value and the ground current and calculates ground resistance,
The calculation output unit calculates ground resistance using the ground current and ground potential values, and corrects it using a correction coefficient,
The calculation output unit,
(a) receiving the installation size of the ground electrode and the installation distance of the measurement ground electrode serving as the infinitely distant reference potential electrode;
(b) measuring the ground current of the ground electrode and the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential and receiving the measured value;
(c) calculating a correction coefficient; and,
(d) performing the step of calculating ground resistance by reflecting the calibration coefficient,
In step (c), the calibration coefficient C _cal (ρ,x) is calculated by the following equation 1. A ground resistance measurement system in a live state using the ground potential of the ground electrode.
[Formula 1]

Here, a and x are the installation radius of the ground electrode and the distance between the measurement ground electrode that serves as a reference potential electrode at an infinite distance from the center of the ground electrode, respectively.
In the ground resistance measurement system in a live state using the ground potential of the ground electrode,
A ground electrode (11) buried in the ground;
In order to measure ground resistance, a measuring ground electrode 16 serves as an infinitely long-distance reference potential electrode;
A current sensor unit 50 that measures the ground current on the ground wire 80 connecting the ground electrode 11;
a voltage measuring unit that measures the voltage between the voltage measuring point (A) on the ground electrode and the voltage measuring point (B) of the measuring potential electrode serving as a reference potential; and,
Comprising an arithmetic output unit that receives the ground potential value and the ground current and calculates ground resistance,
The calculation output unit calculates ground resistance using the ground current and ground potential values, and corrects it using a correction coefficient,
The calculation output unit,
(a) receiving the installation size of the ground electrode and the installation distance of the measurement ground electrode serving as the infinitely distant reference potential electrode;
(b) measuring the ground current of the ground electrode and the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential and receiving the measured value;
(c) calculating a correction coefficient; and,
(d) performing the step of calculating ground resistance by reflecting the calibration coefficient,
In step (d), the grounding resistance is calculated using the following equation 2. A grounding resistance measurement system in a live state using the ground potential of the grounding electrode.
[Formula 2]
,
Here, V _M (ρ,x) represents the measured voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential, and I _g represents the measured ground current. indicates.
In the ground resistance measurement system in a live state using the ground potential of the ground electrode,
A ground electrode (11) buried in the ground;
In order to measure ground resistance, a measuring ground electrode 16 serves as an infinitely long-distance reference potential electrode;
A current sensor unit 50 that measures the ground current on the ground wire 80 connecting the ground electrode 11;
a voltage measuring unit that measures the voltage between the voltage measuring point (A) on the ground electrode and the voltage measuring point (B) of the measuring potential electrode serving as a reference potential; and,
Comprising an arithmetic output unit that receives the ground potential value and the ground current and calculates ground resistance,
The calculation output unit calculates ground resistance using the ground current and ground potential values, and corrects it using a correction coefficient,
The calculation output unit,
An electrode size input unit that receives the installation size of the ground electrode;
an inter-electrode distance input unit that receives the distance between the ground electrode and the measuring welding ground electrode that serves as the reference potential electrode of the infinite distance;
A voltage input unit that receives the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential;
a current input unit that receives a current value of the ground current of each ground line;
a calibration coefficient calculation unit that calculates a calibration coefficient using the size of the ground electrode and the distance between the electrodes; and,
A ground resistance calculation unit that calculates ground resistance using the voltage, current value, and correction coefficient,
The grounding resistance calculation unit calculates the grounding resistance R _g according to the following equation 3. A grounding resistance measurement system in a live state using the ground potential of the grounding electrode.
[Formula 3]

However, C _cal (ρ,x) is the calibration coefficient, and V _M (ρ,x) is the measured voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential. is the voltage value, and I _g is the ground current value.
In the method of measuring ground resistance in a live wire state using the ground potential of the ground electrode through a ground electrode for grounding electrical equipment and a measurement ground electrode that serves as a reference potential electrode at an infinite distance,
(a) receiving the installation size of the ground electrode and the installation distance of the measurement ground electrode serving as the infinitely distant reference potential electrode;
(b) measuring the ground current of the ground electrode and the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential and receiving the measured value;
(c) calculating a correction coefficient; and,
(d) performing the step of calculating ground resistance by reflecting the calibration coefficient,
In step (c), the calibration coefficient C _cal (ρ,x) is calculated using the following equation 1. A method of measuring ground resistance in a live state using the ground potential of the ground electrode.
[Formula 1]

Here, a and x are the installation radius of the ground electrode and the distance between the measurement ground electrode that serves as a reference potential electrode at an infinite distance from the center of the ground electrode, respectively.
In the method of measuring ground resistance in a live wire state using the ground potential of the ground electrode through a ground electrode for grounding electrical equipment and a measurement ground electrode that serves as a reference potential electrode at an infinite distance,
(a) receiving the installation size of the ground electrode and the installation distance of the measurement ground electrode serving as the infinitely distant reference potential electrode;
(b) measuring the ground current of the ground electrode and the voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode serving as a reference potential and receiving the measured value;
(c) calculating a correction coefficient; and,
(d) performing the step of calculating ground resistance by reflecting the calibration coefficient,
In step (d), the grounding resistance is calculated using the following equation 2. A method of measuring grounding resistance in a live state using the ground potential of the grounding electrode.
[Formula 2]
,
Here, V _M (ρ,x) represents the measured voltage between the voltage measurement point (A) on the ground electrode and the voltage measurement point (B) of the measurement potential electrode that serves as the reference potential, and I _g represents the measured ground current. indicates.

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