Ground resistance measurement system and ground resistance measurement method

Abstract

To allow a general-purpose clamp sensor to be used as a clamp sensor connected to a ground resistance measuring device.SOLUTION: A ground resistance measuring system 1 has a ground resistance measuring device 3 that measures the ground resistance of a grounding electrode 9 to be measured, and a clamp sensor that measures the current of the grounding electrode 9 to be measured. The clamp sensor outputs current data to the ground resistance measuring device 3 by wireless communication, and the ground resistance measuring device 3 calculates the ground resistance of the grounding electrode 9 to be measured based on the current data. Therefore, since the current value detected by the clamp sensor is used for calculation, the clamp sensor does not need to be a dedicated apparatus that can be connected to the ground resistance measuring device 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a ground resistance measurement system and a ground resistance measurement method. [Background technology]

[0002] Grounding work performed on electrical equipment is considered essential for human safety and equipment maintenance. During grounding work, a ground resistance measurement system is used to measure the magnitude of the ground resistance of the ground electrode to be measured that is buried in the ground (see, for example, Patent Document 1). For example, as shown in FIG. 3, when measuring ground resistance using a ground resistance measurement system 100, the ground resistance of the ground electrode to be measured is repeatedly measured by the three-electrode method using a first auxiliary ground electrode and a second auxiliary ground electrode connected to a connection cable.

[0003] A conventional method for measuring ground resistance is described below. As shown in Fig. 3, a ground electrode 109 to be measured, a first auxiliary ground electrode 111 functioning as a potential electrode, and a second auxiliary ground electrode 113 functioning as a current electrode are driven into the earth 120. One ends of connection cables 115, 117, and 119 are connected to the ground electrode 109 to be measured, the first auxiliary ground electrode 111, and the second auxiliary ground electrode 113 (ground resistance X5), respectively. The other ends of connection cables 115, 117, and 119 are connected to the E terminal, P terminal, and C terminal of a ground resistance measuring device 103, respectively. Clamp meter 105 having a current detection unit (clamp sensor functioning as a current sensor) 126 is attached to the ground electrode 109 to acquire data on the current of the ground electrode 109 to be measured. The connection cable 116 is for connecting to other ground electrodes to be measured (not shown), and in the example of Figure 4, other ground electrodes to be measured corresponding to ground resistances X2 and X3 are connected to the connection cable 116.

[0004] As shown in Fig. 4, the ground resistance measuring device 103 has a signal generating unit 122 and a voltage detecting unit 124. The signal generating unit 122 generates an AC voltage of a predetermined amplitude (for example, a sine wave voltage). The output is directed to the earth electrode 109 to be measured.

[0005] The current detection unit 126 measures the current value of the AC current flowing through a current path (measurement loop) including the signal generation unit 122, the ground electrode under measurement 109, and the second auxiliary ground electrode 113. The voltage detection unit 124 measures the voltage between the ground electrode under measurement 109 and the first auxiliary ground electrode 111.

[0006] The ground resistance X1 of the ground electrode 109 under test is calculated based on the voltage obtained by the voltage detection unit 124 and the current obtained by the current detection unit 126. Note that when calculating the ground resistance X1, the complex components of the voltage and current are found and the complex ground resistance is calculated. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2014-119277 Summary of the Invention [Problem to be solved by the invention]

[0008] In the above-mentioned earth resistance measurement system, the earth resistance measuring device 103 and the clamp meter 105 are connected by wire, and current measurements are also made using the current detection unit within the earth resistance measuring device 103, so the clamp meter 105 must be a dedicated device that matches the specifications (measurement range, etc.) of the earth resistance measuring device 103.

[0009] An object of the present invention is to provide a ground resistance measurement system and a ground resistance measurement method in which a general-purpose clamp sensor can be used as a clamp sensor connected to a ground resistance measurement device. [Means for solving the problem]

[0010] In order to solve the above problem, one aspect of the ground resistance measurement system of the present invention is characterized in that it has a ground resistance measurement device that measures the ground resistance of the ground electrode being measured and a clamp sensor that measures the current of the ground electrode being measured, the clamp sensor outputs current data to the ground resistance measurement device via wireless communication, and the ground resistance measurement device calculates the ground resistance of the ground electrode being measured based on the current data.

[0011] Another aspect of the ground resistance measurement system of the present invention is that the ground resistance measurement device has a voltage detection unit that detects a second voltage between the ground electrode to be measured and an auxiliary ground electrode adjacent to the ground electrode to be measured based on a first voltage applied to the ground electrode to be measured from the signal generation unit, and a current detection unit that detects a current flowing through a current path including the ground electrode to be measured from the signal generation unit, and the ground resistance measurement device determines the phase difference between the current measured by the current detection unit and the second voltage based on the current and the second voltage, and calculates the ground resistance based on the current value and phase difference of the current output from the clamp sensor.

[0012] Another aspect of the ground resistance measurement system according to the present invention is characterized in that the clamp sensor is provided with a display unit that displays the calculated ground resistance.

[0013] Another aspect of the ground resistance measurement system of the present invention is characterized in that it has a mobile terminal connected to the ground resistance measurement device and the clamp sensor via wireless communication via a network, and the mobile terminal determines the phase difference between the current measured by the current detection unit and the second voltage based on the current and the second voltage, and calculates and displays the ground resistance based on the current value and phase difference of the current output from the clamp sensor.

[0014] Furthermore, one aspect of the ground resistance measurement method according to the present invention is characterized in that it comprises a step in which a ground resistance measurement device measures the ground resistance of the ground electrode being measured, a step in which a clamp sensor measures the current of the ground electrode being measured, a step in which the clamp sensor outputs the current data to the ground resistance measurement device via wireless communication, and a step in which the ground resistance measurement device calculates the ground resistance of the ground electrode being measured based on the current data. [Effects of the Invention]

[0015] According to the present invention, a general-purpose clamp sensor can be used as the clamp sensor connected to the ground resistance measuring device. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing the configuration of a ground resistance measurement system according to an embodiment of the present invention. [Figure 2] 1 is a diagram for explaining the operation of a ground resistance measurement system according to an embodiment of the present invention. FIG. [Figure 3] FIG. 1 is a diagram showing the configuration of a conventional ground resistance measurement system. [Figure 4] 1 is a diagram for explaining the operation of a conventional ground resistance measurement system. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] <One embodiment> A ground resistance measuring system according to an embodiment of the present invention will be described below with reference to FIGS.

[0018] FIG. 1 is a diagram showing the configuration of a ground resistance measurement system according to one embodiment of the present invention, and FIG. 2 is a diagram for explaining the operation of the ground resistance measurement system according to one embodiment of the present invention.

[0019] [Configuration of Earth Resistance Measurement System 1] Ground resistance measurement system 1 includes a ground resistance measurement device 3 and a clamp meter 5. In this embodiment, a clamp sensor with a display unit is referred to as a clamp meter, but the effects of the ground resistance measurement system according to this embodiment, described below, can also be obtained with a clamp sensor that does not have a display unit and functions as a clamp ammeter on its own, rather than clamp meter 5. This is because, as will be described later, a display unit that displays the ground resistance is also provided in ground resistance measurement device 3, and, as will be described later in the modified example, the display can also be displayed on a separate display unit of a mobile terminal.

[0020] Data is transmitted and received between the earth resistance measuring device 3 and the clamp meter 5 via wireless communication (e.g., Wi-Fi (registered trademark), Bluetooth (registered trademark), etc.). The mobile terminal 7 has the ability to wirelessly communicate various data between the earth resistance measuring device 3 and the clamp meter 5 (e.g., Wi-Fi (registered trademark), Bluetooth (registered trademark), etc.), but is an additional component rather than an essential component of the earth resistance measurement system 1, and details of this will be described later. The earth electrode 9 to be measured, the first auxiliary earth electrode 11 functioning as a potential electrode, and the second auxiliary earth electrode 13 functioning as a current electrode are driven into the ground 30. One end of a connection cable 15, a connection cable 17, and a connection cable 19 are connected to the earth electrode 9 to be measured, the first auxiliary earth electrode 11, and the second auxiliary earth electrode 13, respectively. The other ends of the connection cables 15, 17, and 19 are connected to the E terminal, P terminal, and C terminal, respectively, of the earth resistance measuring device 3.

[0021] As shown in FIG. 2, the ground resistance measuring device 3 includes a signal generating unit (voltage generating circuit) 20, a current detecting unit 22, a voltage detecting unit 24, a control unit 10, a memory unit 12, and a display unit 14. The signal generating unit 20 generates and outputs an AC voltage (e.g., a sinusoidal voltage) of a predetermined amplitude. The current detecting unit 22 has one end connected to the signal generating unit 20 and the other end connected to the ground electrode 9 under test. The current detecting unit 22 detects a current It that flows in accordance with the AC voltage output from the signal generating unit 20 and outputs the detected current to the control unit 10. Here, the current It is a current that flows through a current path (current measurement loop) that includes the ground electrode 9 under test and the second auxiliary grounding electrode 13. The voltage detecting unit 24 receives a detection command from the control unit 10 and detects the voltage V (voltage drop) between the ground electrode 9 under test and the first auxiliary grounding electrode 11.

[0022] The control unit 10 is configured to include, for example, a computing element such as a CPU and an internal memory, and receives a signal corresponding to a user's operation input from an operation input unit (not shown), and performs the earth resistance measurement process described below based on the measured current value supplied from the current detection unit 22 and the measured voltage value supplied from the voltage detection unit 24.

[0023] The storage unit 12 is configured by, for example, a semiconductor memory or a hard disk, and stores in advance operation programs to be executed by the arithmetic elements of the control unit 10, such as a CPU.

[0024] The display unit 14 is configured with a display device such as an LCD (Liquid Crystal Display), and displays the results of each process executed by the control unit 10 on the screen.

[0025] The clamp meter 5 has a current detection unit 26, which detects the current value of the current Ic flowing through the ground electrode 9 to be measured via a wireless connection (Ic in equation (1) described later means this current value), and outputs information on the detected current value Ic to the control unit 10.

[0026] [Calculation method for ground resistance] Zero adjustment is performed after clamping the ground electrode 9 under test with the clamp meter 5. The control unit 10 controls the signal generation unit 20 to apply a predetermined first voltage between the ground electrode 9 under test and the second auxiliary ground electrode 13. A calculation unit (not shown) constituting the control unit 10 calculates the phase difference θ between the voltage and current based on the second voltage V between the ground electrode 9 under test and the first auxiliary ground electrode 11 calculated by the voltage detection unit 24 and the current It obtained by the current detection unit 26, based on the applied predetermined first voltage. Here, because the ground resistance is calculated using the real part, the voltage amplitude can be expressed as Vcosθ when the current phase is used as the reference.

[0027] Meanwhile, the current detection unit 26 implemented in the clamp meter 5 detects the current value (Ic) of the current Ic flowing through the ground resistance X1 of the earth electrode 9 under test, and outputs the detected current value (Ic) of the current Ic to the control unit 10. Note that since the earth resistance X1 of the earth electrode 9 under test is one of the resistances of the multiple grounded earth electrodes (X1, X2, and X3 in the example of Figure 2), It ≠ Ic, but It and Ic are in phase.

[0028] The calculation unit that constitutes the control unit 10 calculates the ground resistance Rx1 (X1 in Figure 2) by calculating the following formula (1) based on the voltage (voltage value) V and phase difference θ between the measured ground electrode 9 and the first auxiliary ground electrode 11, and the current (current value) Ic. Rx1=Vcosθ / Ic (1)

[0029] In calculating the ground resistance, the ground resistance Rx1 calculated by a calculation unit (not shown) that constitutes the ground resistance measuring device 3 is displayed on the display unit 14 of the ground resistance measuring device 3.

[0030] According to the above-described ground resistance measurement system and method, the current value Ic detected by current detection unit 26 of clamp meter 5 is used in the calculation, so clamp meter 5 does not need to be a dedicated device that can be connected to ground resistance measurement device 3. In other words, in the past, the choice of clamp meter was limited to those that could be connected to ground resistance measurement device 3 by wire, resulting in little freedom of choice. However, according to the ground resistance measurement system and method of this embodiment, the selected clamp meter 5 is not limited to dedicated devices that can be connected to ground resistance measurement device 3, so the freedom of choice of clamp meter 5 is improved.

[0031] Furthermore, because the phase difference θ between the detected voltage V and the detected current It is determined on the ground resistance measuring device 3 side, the ground resistance can be determined regardless of the phase characteristics of the clamp meter side. Even when a current due to external noise (such as eddy current) is flowing, the zero adjustment function of the clamp meter 5 can be executed to cancel the noise, improving the accuracy of the ground resistance measurement.

[0032] [Variations] According to the embodiment described above, the calculation of ground resistance Rx1 is performed by a calculation unit constituting control unit 10 of ground resistance measuring device 3, and the calculation result is displayed on display unit 14 of ground resistance measuring device 3. However, a calculation unit (not shown) may be provided within clamp meter 5 to calculate ground resistance Rx1 there, or a calculation unit (not shown) may be provided within mobile terminal 7 (see FIG. 1) to calculate ground resistance Rx1 there. The calculation result may also be displayed on display unit 6 of clamp meter 5, or on display unit 8 of mobile terminal 7 (see FIG. 1).

[0033] According to the above-described modified example, the calculation results can be checked on a device other than the display unit 14 of the earth resistance measuring device 3, so that the calculation results can be checked quickly regardless of the location, and measurement processing can be performed efficiently.

[0034] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0035] [Summary of effects] The ground resistance measurement system 1 of this embodiment has a ground resistance measurement device 3 that measures the ground resistance Rx1 of the ground electrode 9 to be measured, and a clamp sensor that measures the current of the ground electrode 9 to be measured, and the clamp sensor outputs current data to the ground resistance measurement device 3 via wireless communication, and the ground resistance measurement device 3 calculates the ground resistance Rx1 of the ground electrode 9 to be measured based on the current data. Therefore, according to the above configuration, the current value Ic detected by the current detection unit 26 of the clamp sensor (clamp meter 5 (clamp sensor with display unit)) is used for calculation, so the clamp sensor does not need to be a dedicated device that can be connected to the earth resistance measuring device 3.

[0036] In the ground resistance measurement system 1 according to this embodiment, the ground resistance measurement device 3 includes a voltage detection unit 24 that detects a second voltage V between the measured ground electrode 9 and the auxiliary ground electrode (first auxiliary ground electrode) 11 adjacent to the measured ground electrode 9 based on a first voltage applied to the measured ground electrode 9 from the signal generation unit 20, and a current detection unit 22 that detects a current It flowing from the signal generation unit 20 through a current path including the measured ground electrode 9. The ground resistance measurement device 3 determines a phase difference θ between the current It measured by the current detection unit 22 and the second voltage V, and calculates the ground resistance Rx1 based on the current value Ic of the current output from the clamp sensor and the phase difference θ. According to the above configuration, the ground resistance Rx1 is calculated based on the current value Ic detected by the current detection unit 26 of the clamp sensor (clamp meter 5 (clamp sensor with display unit)) and the phase difference θ. Therefore, the ground resistance Rx1 can be calculated without depending on the phase characteristics of the clamp sensor.

[0037] In the ground resistance measurement system 1 according to this embodiment, the clamp sensor is provided with a display unit 6 that displays the calculated ground resistance. Therefore, according to the above configuration, the calculated ground resistance can be displayed on the display unit 6 provided in the clamp sensor (clamp meter 5 (clamp sensor with display unit)), allowing the calculation results to be quickly confirmed.

[0038] The ground resistance measurement system 1 according to this embodiment includes a mobile terminal 7 that is wirelessly connected to the ground resistance measurement device 3 and the clamp sensor via a network, and the mobile terminal 7 determines the phase difference between the current It measured by the current detection unit and the second voltage V, and calculates and displays the ground resistance Rx1 based on the current value Ic of the current output from the clamp sensor and the phase difference θ. Therefore, according to the above configuration, the calculation results can be confirmed on places other than the display unit 14 of the earth resistance measuring device 3, so the calculation results can be quickly confirmed regardless of the location, and measurement processing can be performed efficiently.

[0039] The ground resistance measurement method of this embodiment includes a step in which the ground resistance measurement device 3 measures the ground resistance Rx1 of the ground electrode being measured, a step in which the clamp sensor measures the current of the ground electrode being measured, a step in which the clamp sensor outputs current data to the ground resistance measurement device 3 via wireless communication, and a step in which the ground resistance measurement device 3 calculates the ground resistance Rx1 of the ground electrode being measured based on the current data. Therefore, according to the above configuration, the current value Ic detected by the current detection unit 26 of the clamp sensor (clamp meter 5 (clamp sensor with display unit)) is used for calculation, so the clamp sensor does not need to be a dedicated device that can be connected to the earth resistance measuring device 3. [Explanation of symbols]

[0040] 1. Ground resistance measurement system 3 Earth resistance measuring device 5. Clamp meter (clamp sensor with display) 6 Display section 7. Mobile devices 8 Display 9 Ground electrode to be measured 10 Control Unit 11 1st auxiliary ground electrode 12 Storage section 13 2nd auxiliary ground electrode 14 Display section 15, 17, 19 Connection cables 20 Signal generation unit (voltage generation circuit) 22 Current detection section 24 Voltage detection section 30 Earth

Claims

1. a ground resistance measuring device for measuring the ground resistance of the ground electrode to be measured; a clamp sensor for measuring the current of the ground electrode to be measured; and The clamp sensor outputs the current data to the ground resistance measuring device via wireless communication, The ground resistance measurement device is a ground resistance measurement system that calculates the ground resistance of the ground electrode to be measured based on the current data, The ground resistance measuring device is a voltage detection unit that detects a second voltage between the ground electrode to be measured and an auxiliary ground electrode adjacent to the ground electrode to be measured based on a first voltage applied to the ground electrode to be measured from a signal generation unit; a current detection unit that detects a current that flows from the signal generation unit through a current path that includes the ground electrode under test and is based on the first voltage; and a phase difference between the current measured by the current detection unit and the second voltage is determined, and a ground resistance is calculated based on the current value of the current output from the clamp sensor and the phase difference; A ground resistance measurement system characterized by:

2. The clamp sensor is provided with a display unit that displays the calculated ground resistance.

2. The ground resistance measuring system according to claim 1.

3. A mobile terminal is connected to the ground resistance measuring device and the clamp sensor by wireless communication via a network, The mobile terminal determines a phase difference between the current measured by the current detection unit and the second voltage, and calculates and displays a ground resistance based on the current value of the current output from the clamp sensor and the phase difference.

3. The ground resistance measuring system according to claim 1 or 2.

4. A step in which a ground resistance measuring device measures the ground resistance of a ground electrode to be measured; a clamp sensor measuring the current of the ground electrode to be measured; and The clamp sensor outputs the current data to the ground resistance measuring device by wireless communication; The ground resistance measuring device includes a step of calculating the ground resistance of the ground electrode to be measured based on the current data, The ground resistance measuring device has a voltage detection unit and a current detection unit, the voltage detection unit detects a second voltage between the measured ground electrode and an auxiliary ground electrode adjacent to the measured ground electrode based on a first voltage applied to the measured ground electrode from the signal generation unit; the current detection unit detects a current flowing from the signal generation unit through a current path including the ground electrode under test, the current being based on the first voltage; The ground resistance measuring device determines a phase difference between the current measured by the current detection unit and the second voltage, and calculates the ground resistance based on the current value of the current output from the clamp sensor and the phase difference. A method for measuring ground resistance.

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