JP2014115142A - Ground resistance meter, ground resistance measuring method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict the minimum value of a measurement result based on a state of an auxiliary earth pole.SOLUTION: In steps S1 to S4, the resistance value of a combined ground resistance Rep, the resistance value of a combined ground resistance Rec, the resistance value of a combined ground resistance Rpc, the resistance value of a ground resistance Rp, and the resistance value of a ground resistance Rc are calculated, respectively. In step 5, when it is determined that a measurement start is instructed, in step S6, an AC voltage V1 is applied between a measured ground body E and a second auxiliary ground pole C, and a current value injected to a second auxiliary ground pole C and a voltage value between the measured ground body E and a first auxiliary ground pole P are measured. In step S7, the resistance value of the ground resistance Re is obtained. In step S8, when both of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc are determined to be equal to or not more than a prescribed value, in step S9, the ground value is displayed, and when at least one of the ground resistance values Rp and Rc is not determined to be equal to or not more than the prescribed value, in step 10, the resistance value of the ground resistance Re is displayed by restricting the minimum value.

Description

  The present invention relates to a ground resistance meter, a ground resistance measurement method, and a program.

  Grounding work applied to electrical facilities is considered indispensable for the safety of human bodies and the maintenance of equipment. During grounding work, a grounding resistance meter is used to measure the grounding resistance of the grounding body buried in the ground. Some earth resistance meters are based on the AC potential difference method.

  When measuring the ground resistance, a measurement ground E embedded in the ground is connected to the measurement terminal E of the ground resistance meter, and the measurement terminal P and the measurement terminal C are respectively connected to the ground at different locations. The embedded auxiliary earthing poles are connected to each other.

  Conventionally, a ground resistance meter has been used that can easily determine whether the auxiliary ground resistance is good and can measure the ground resistance of a grounding body embedded in the ground with high accuracy (for example, Patent Document 1). ).

  In the above-described ground resistance meter, the ground state of the first auxiliary ground electrode is determined using the composite ground resistance Rep (= Re + Rp), and the second auxiliary ground using the composite ground resistance Rec (= Re + Rc). The grounding state of the grounding electrode is determined. For this reason, when the grounding resistance Re of the measured ground body E is large, it is determined that the grounding state is not good even though the grounding state of the first auxiliary grounding electrode and the second auxiliary grounding electrode is actually good. End up. On the other hand, a ground resistance meter that can reliably determine the ground state of at least the first auxiliary ground electrode and the second auxiliary ground electrode has been used (for example, Patent Document 2).

JP-A-11-118851 Japanese Patent Application Laid-Open No. 2011-226983

  When the ground resistance meter is used for actual measurement, as described above, the measured ground body embedded in the ground is connected to the measurement terminal E of the ground resistance meter, and the measurement terminal P and the measurement terminal are connected to the ground resistance meter. A first auxiliary grounding electrode and a second auxiliary grounding electrode embedded in the ground at different locations are connected to C, respectively.

  In the measurement of the ground resistance, a voltage is applied between the second auxiliary ground electrode connected to the measurement terminal C and the measured ground body connected to the measurement terminal E, so that the measurement terminal C is connected. The current flowing through the second auxiliary grounding electrode is measured, and the voltage between the first auxiliary grounding electrode connected to the measurement terminal P and the measured ground connected to the measurement terminal E is measured. . Using the measurement results of the current and voltage, the ground resistance of the measured ground connected to the measurement terminal E is measured, and the measurement result is displayed.

  At this time, in the case where the ground resistance of the measured ground body is good and the ground resistance meter displays a value lower than the true value, “0.00Ω” may be displayed as the measured value.

  For example, when a measured grounding object with a ground resistance of 0.1Ω is measured with a grounding resistance meter with a measurement accuracy of ± 2% rdg and ± 0.1Ω, the measured value is 0 to 0.2Ω. Although the ground resistance is not 0Ω, “0.00Ω” may be displayed as the measured value.

As described above, it is generally recognized that the measured value can be “0.00Ω” depending on the specifications of the ground resistance meter, but the ground resistance cannot be 0Ω. The accuracy of the ground resistance meter described above is hardly considered, and “0.00Ω” as a measured value is not practically accepted. The measurement result is often reported by taking a photograph of the display unit of the ground resistance meter, and the measurement result displayed as “0.00Ω” cannot be used.

  On the other hand, when the ground resistance meter is calibrated or checked for failure, the measurement result is “0Ω” when all the measurement terminals E, P, and C are short-circuited. "Is displayed. In addition, the test of whether or not the product specification is satisfied in accordance with the international standard IEC61557-5 of the ground resistance meter is performed by the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the grounding of the second auxiliary grounding pole C. It is determined to be executed under the condition that the resistance value of the resistor Rc is within a range of 100Ω ± 3%. Thus, even in a test in which measurement conditions are determined, “0Ω” must be displayed as a measurement result as necessary. That is, it is not possible to simply prohibit display of “0.00Ω” or the like on the ground resistance meter.

  Therefore, the present invention solves the above-described problem, that is, a ground resistance meter and a ground resistance measurement method capable of limiting the minimum value of the measurement result as necessary based on the state of the auxiliary ground electrode, As well as providing a program.

  In order to solve the above problems, one aspect of the ground resistance meter of the present invention includes a signal generation unit that generates an AC voltage, and a current value of a current that flows through a predetermined circuit by the AC voltage generated by the signal generation unit. Current measuring means, voltage measuring means for measuring a voltage value of a voltage applied to a predetermined circuit by the alternating voltage generated by the signal generating means, a first connection terminal, a second connection terminal, and a first Switching means for switching the circuit to which the three connection terminals are connected, switching control means for controlling switching of the circuit by the switching means, and a current value measured by the current measuring means in the predetermined circuit switched by the switching means, And based on the voltage value measured by the voltage measuring means, the ground resistance value of the first auxiliary grounding electrode and the connection of the second auxiliary grounding electrode Based on the current value measured by the current measuring means and the voltage value measured by the voltage measuring means in the predetermined circuit switched by the switching means and the first calculating means for calculating the resistance value A second calculating means for calculating a grounding resistance value of the grounding body, and a grounding resistance value of the first auxiliary grounding electrode and a grounding resistance value of the second auxiliary grounding electrode calculated by the first calculating means Based on the result of comparison and the processing result of the comparison means, the display of the ground resistance value of the measured ground body calculated by the second calculation means is controlled, or the minimum value is limited. And a display control means for controlling the display of the ground resistance value of the ground member to be measured.

  In another aspect of the present invention, the comparison unit compares the ground resistance value of the first auxiliary grounding pole calculated by the first calculation unit with a predetermined first value, and calculates by the first calculation unit. The ground resistance value of the second auxiliary ground electrode is compared with a predetermined second value, and the display means determines that the ground resistance value of the first auxiliary ground pole is a predetermined first value based on the processing result of the comparison means. If the ground resistance value of the second auxiliary grounding electrode is less than a predetermined second value, the ground resistance value of the measured ground body calculated by the second calculating means is displayed. And at least whether the ground resistance value of the first auxiliary ground electrode is equal to or greater than a predetermined first value, or the ground resistance value of the second auxiliary ground electrode is equal to or greater than a predetermined second value. If it is either, the minimum value is limited and the ground of the measured ground body calculated by the second calculation means And controlling the display of the anti-values.

  In another aspect of the present invention, the comparison unit compares the ground resistance value of the first auxiliary grounding electrode and the grounding resistance value of the second auxiliary grounding electrode calculated by the first calculation unit with a predetermined range, The display control means determines whether at least one of the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode calculated by the first calculation means is predetermined based on the processing result of the comparison means. If it is within the range, the display of the ground resistance value of the measured ground body calculated by the second calculation means is controlled, and the ground resistance value of the first auxiliary ground electrode calculated by the first calculation means When both of the ground resistance values of the second auxiliary grounding electrode and the second auxiliary grounding electrode are not within the predetermined range, the minimum value is limited to control the display of the ground resistance value of the measured ground body calculated by the second calculation means. It is characterized by doing.

  Another aspect of the present invention is characterized in that the predetermined range is 100Ω ± 3%.

  In another aspect of the present invention, the comparison unit compares the ground resistance value of the first auxiliary grounding pole calculated by the first calculation unit with a predetermined first value, and calculates by the first calculation unit. The ground resistance value of the second auxiliary grounding electrode is compared with a predetermined second value, and the grounding resistance value of the first auxiliary grounding electrode and the second auxiliary grounding calculated by the first calculating means The ground resistance value of the pole is compared with a predetermined range, and the display control means determines the ground resistance value of the first auxiliary ground pole calculated by the first calculation means based on the processing result of the comparison means. Is less than 1 and the ground resistance value of the second auxiliary ground electrode calculated by the first calculation means is less than a predetermined second value, or is calculated by the first calculation means. The ground resistance value of the first auxiliary grounding electrode and the grounding resistance value of the second auxiliary grounding electrode are small. If either of them is within the predetermined range, the display of the ground resistance value of the measured ground body calculated by the second calculation means is controlled, and the ground resistance value of the first auxiliary ground electrode is the predetermined first value. 1 or more, or the ground resistance value of the second auxiliary earthing pole is at least a predetermined second value, and the first calculation means calculated by the first calculation means When both the ground resistance value of the auxiliary grounding electrode and the grounding resistance value of the second auxiliary grounding electrode are not within the predetermined range, the minimum value is limited and the measured grounding body calculated by the second calculating means The display of the ground resistance value is controlled.

  Another aspect of the present invention is characterized in that the predetermined range is 100Ω ± 3%.

  In another aspect of the present invention, the switching control unit calculates the ground resistance value of the first auxiliary grounding electrode and the grounding resistance value of the second auxiliary grounding electrode by the first calculation unit, When the ground resistance value of the grounded body to be measured is calculated by the calculation means of 2, the circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected is different. Thus, the switching means is controlled.

  One aspect of the ground resistance measuring method of the present invention is to generate an alternating voltage, a first switching step of switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected. A first signal generation step, a first current measurement step for measuring a current value of a current flowing in a predetermined circuit by an AC voltage generated by the processing of the first signal generation step, and a first signal generation step In the first voltage measurement step for measuring the voltage value of the voltage applied to the predetermined circuit by the alternating voltage generated by the processing, and the predetermined circuit switched by the processing of the first switching step, the first current Based on the current value measured by the process of the measurement step and the voltage value measured by the process of the first voltage measurement step, the ground resistance value of the first auxiliary ground electrode, and A first calculation step of calculating a ground resistance value of the second auxiliary ground electrode, and a second switching for switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected A second signal generating step for generating an AC voltage; a second current measuring step for measuring a current value of a current flowing in a predetermined circuit by the AC voltage generated by the processing of the second signal generating step; The second voltage measurement step for measuring the voltage value of the voltage applied to the predetermined circuit by the AC voltage generated by the processing of the second signal generation step and the predetermined voltage switched by the processing of the second switching step In this circuit, the grounding resistance of the measured ground body is determined based on the current value measured in the second current measuring step and the voltage value measured in the second voltage measuring step. And a comparison for comparing the ground resistance value of the first auxiliary grounding electrode and the ground resistance value of the second auxiliary grounding electrode calculated by the first calculation step with a predetermined value. Based on the processing results of the step and the comparison step, the display of the grounding resistance value of the measured ground body calculated by the second calculation step is controlled, or the minimum value is limited, and the second calculation step And a display control step for controlling display of the grounding resistance value of the grounded body to be measured calculated by the above.

  One aspect of the program of the present invention is a first switching step of switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected, and a first switching circuit that generates an AC voltage. Generated by the signal generation step, the first current measurement step of measuring the current value of the current flowing through the predetermined circuit by the AC voltage generated by the processing of the first signal generation step, and the processing of the first signal generation step In the first voltage measurement step for measuring the voltage value of the voltage applied to the predetermined circuit by the alternating current voltage and the predetermined circuit switched by the processing of the first switching step, the first current measurement step Based on the current value measured by the process and the voltage value measured by the process of the first voltage measurement step, the ground resistance value of the first auxiliary ground electrode, and the second A first calculation step of calculating a ground resistance value of the auxiliary grounding electrode; a second switching step of switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected; A second signal generation step for generating an AC voltage; a second current measurement step for measuring a current value of a current flowing in a predetermined circuit by the AC voltage generated by the processing of the second signal generation step; A second voltage measurement step for measuring a voltage value of a voltage applied to a predetermined circuit by an AC voltage generated by the signal generation step processing, and a predetermined circuit switched by the second switching step processing Based on the current value measured in the second current measurement step and the voltage value measured in the second voltage measurement step, the ground resistance value of the measured ground body is calculated. And a comparison step of comparing the ground resistance value of the first auxiliary grounding electrode and the grounding resistance value of the second auxiliary grounding electrode calculated by the first calculation step with a predetermined value. Based on the processing result of the comparison step, the display of the ground resistance value of the measured ground body calculated by the second calculation step is controlled, or the minimum value is limited and the calculation is performed by the second calculation step. And a display control step for controlling display of the ground resistance value of the measured grounding body.

  According to the present invention, the minimum value of the measurement result can be limited as necessary based on the state of the auxiliary ground electrode.

It is a figure which shows the 1st structural example of a grounding resistance meter. It is a functional block diagram for demonstrating the function which a control part has. 5 is a flowchart for explaining a ground resistance measurement process 1; It is a figure which shows the 2nd structural example of a grounding resistance meter. It is a functional block diagram for demonstrating the function which a control part has. 10 is a flowchart for explaining a ground resistance measurement process 2;

  First, referring to FIG. 1, FIG. 2, and FIG. 3, in the first example of a ground resistance meter capable of limiting the minimum value of the measurement result as required based on the state of the auxiliary ground electrode. A certain earth resistance meter 1 will be described.

  With reference to FIG. 1, the configuration of the ground resistance meter 1 will be described.

  The ground resistance meter 1 includes a signal generation unit 11, a current measurement unit 12, a voltage measurement unit 13, a control unit 14, a storage unit 15, a display unit 16, an operation input unit 17, a switching processing unit 18, and connection terminals 31 and 32. , 33. The ground resistance meter 1 uses the first auxiliary grounding pole P connected to the connection terminal 31 and the second auxiliary grounding pole C connected to the connection terminal 32 to measure the ground resistance. The ground resistance Re of the measured ground body E connected to is repeatedly measured by the three-electrode method.

  The signal generation unit 11 generates an alternating voltage (a sine wave voltage as an example) V1 having a constant frequency (known frequency) and a constant amplitude based on control of the control unit 14 to be described later, and a pair of output terminals. (Not shown). In the signal generation unit 11, the first output terminal of the pair of output terminals is connected to the current measurement unit 12 described later, and the second output terminal is connected to the switch 42 of the switching processing unit 18 described later. .

  The current measuring unit 12 is configured by an AC ammeter as an example, a first input terminal of a pair of input terminals (not shown) is connected to a first output terminal of the signal generation unit 11, and a second Are connected to a switch 41 of the switching processing unit 18 to be described later, so that the AC current I1 is connected in series to the signal generation unit 11 and flows through the current path (measurement loop) including the signal generation unit 11. The current value is measured at a predetermined cycle (as an example, a cycle synchronized with the cycle of the AC voltage V1). Further, each time the current measurement unit 12 measures the current value, the current measurement unit 12 outputs the measured current value (hereinafter also referred to as “measurement current value”) to the control unit 14 described later.

  The voltage measuring unit 13 is configured by an AC voltmeter as an example, and a first input terminal of a pair of input terminals (not shown) is connected to a switch 43 of the switching processing unit 18 to be described later, and the second Is connected to a second input terminal of the current measuring unit 12 (a terminal connected to a switch 41 of the switching processing unit 18 described later), and the voltage value of the AC voltage generated at both ends thereof is determined in advance. Measurement is performed at a cycle (as an example, a cycle synchronized with the cycle of the AC voltage V1). In addition, each time the voltage measurement unit 13 measures the voltage value, the voltage measurement unit 13 outputs the measured voltage value (hereinafter also referred to as “measurement voltage value”) to the control unit 14 described later.

  The control unit 14 includes, for example, an arithmetic element such as a CPU, an internal memory, and the like. The control unit 14 receives an input of a signal corresponding to a user operation input from the operation input unit 17 to be described later and supplies the signal from the current measurement unit 12. Based on the measured current value and the measured voltage value supplied from the voltage measuring unit 13, processing including ground resistance measurement processing 1 described later with reference to FIG. 3 is executed. In this case, the internal memory functions as a work memory for the CPU.

  That is, the control unit 14 controls the signal generation unit 11 and the switching processing unit 18 to connect the ground resistance Rp of the first auxiliary grounding pole P connected to the connection terminal 31 and the connection terminal 32. After measuring the grounding resistance Rc of the two auxiliary grounding poles C, the grounding resistance Re of the measured ground body E connected to the connection terminal 33 is measured by the three-electrode method. When the ground resistance Rp of the first auxiliary grounding pole P and the grounding resistance Rc of the second auxiliary grounding pole C are both lower than a predetermined value, the control unit 14 The measured value of the ground resistance Re is displayed on the display unit 16, and at least one of the ground resistance Rp of the first auxiliary ground pole P and the ground resistance Rc of the second auxiliary ground pole C is higher than a predetermined value. In this case, the measured value of the ground resistance Re of the measured ground E is prohibited from being displayed as 0Ω on the display unit 16, and for example, the minimum value of the measurement result is limited to a value such as “0.01Ω”, The measured value of the grounding resistance Re of the measured ground E is displayed on the display unit 16.

  Details of the functions of the control unit 14 will be described later using the functional blocks of FIG.

  The storage unit 15 is composed of, for example, a semiconductor memory or a hard disk, and is used in an operation program executed by an arithmetic element of the control unit 14 such as a CPU and a ground resistance measurement process described with reference to FIG. The ground resistance Rp of the auxiliary ground pole P, the threshold value of the ground resistance Rc of the second auxiliary ground pole C, and the like are stored in advance.

  The display unit 16 is composed of a display device such as an LCD (Liquid Crystal Display), for example, and displays the results of each process executed by the control unit 14 on the screen.

  The operation input unit 17 includes input devices such as buttons, levers, dials, and touch panels, for example, receives an operation input from the user, and supplies a signal indicating the operation input from the user to the control unit 14.

  The switching processing unit 18 includes a switch 41, a switch 42, and a switch 43. The switching processing unit 18 includes, for example, a single-pole double-throw (one circuit, two-contact type) changeover switch based on the control of the control unit 14. The switch 41, the switch 42, and the switch 43 that are being switched are switched. Specifically, the switch 41 controls the second input terminal of the current measurement unit 12 and the second input terminal of the voltage measurement unit 13 connected to the first common contact com1 based on the control of the control unit 14. Then, the connection terminal 31 or the connection terminal 33 is connected. The switch 42 connects the second output terminal of the signal generation unit 11 connected to the second common contact com2 and the switch 43 to the connection terminal 31 or the connection terminal 32 based on the control of the control unit 14. The switch 43 connects the first input terminal of the voltage measuring unit 13 connected to the third common contact com3 to the switch 42 or the connection terminal 31 based on the control of the control unit 14.

  A first auxiliary grounding pole P is connected to the connection terminal 31, a second auxiliary grounding pole C is connected to the connection terminal 32, and a measured ground body E is connected to the connection terminal 33.

  FIG. 2 is a functional block diagram for explaining the functions of the control unit 14.

  The control unit 14 has functions including a voltage application control unit 51, a switching control unit 52, an auxiliary earthing pole grounding resistance calculation unit 53, a comparison unit 54, a measured grounded body grounding resistance calculation unit 55, and a display control unit 56. doing.

  The voltage application control unit 51 controls the signal generation unit 11 to apply the voltage V1 to both ends thereof.

  The switching control unit 52 controls switching of circuits by the switching processing unit 18.

  The auxiliary earthing pole grounding resistance calculation unit 53 is based on the measured current value measured by the current measuring unit 12 and the measured voltage value measured by the voltage measuring unit 13, and the earthing resistance Rp of the first auxiliary earthing electrode P. And the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C are calculated and output to the comparison unit 54.

  Specifically, the auxiliary grounding electrode grounding resistance calculating unit 53 determines the resistance value of the combined grounding resistor Rep, the combined grounding resistance based on the measured current value and the measured voltage value obtained in a predetermined circuit switched by the switching processing unit 18. The resistance value of Rec and the resistance value of the composite ground resistance Rpc are calculated. Then, the auxiliary grounding pole grounding resistance calculating unit 53 solves the simultaneous equations shown in the following formulas (1), (2), and (3), thereby grounding resistance of the first auxiliary grounding pole P. The resistance value of Rp and the resistance value of the ground resistance Rc of the second auxiliary grounding pole C are calculated and supplied to the comparison unit 54.

Rep = Re + Rp
(1)
Rec = Re + Rc
(2)
Rpc = Rp + Rc
(3)

  The comparison unit 54 compares the resistance value of the ground resistance Rp of the first auxiliary ground pole P calculated by the auxiliary ground pole ground resistance calculation unit 53 with the first threshold value stored in the storage unit 15. The resistance value of the ground resistance Rc of the second auxiliary earthing pole C calculated by the auxiliary earthing pole earthing resistance calculating unit 53 is compared with the second threshold value stored in the storage unit 15, and the comparison result is obtained. This is supplied to the display control unit 56.

  The to-be-measured grounded body ground resistance calculating unit 55 is configured to measure the second auxiliary grounding electrode C measured by the current measuring unit 12 in a state where the voltage V1 is applied between the to-be-measured grounding body E and the second auxiliary grounding electrode C. And the voltage value between the measured grounding body E and the first auxiliary grounding pole P measured by the voltage measuring unit 13 is acquired. Then, the measured grounded body ground resistance calculating unit 55 calculates the resistance value of the grounded resistance Re of the measured grounded body E by the three-electrode method based on the acquired measured current value and measured voltage value, and the display control unit 56.

  The display control unit 56 performs the processing of the comparison unit 54 so that the resistance value of the ground resistance Rp of the first auxiliary grounding pole P is less than the first threshold value and the grounding resistance Rc of the second auxiliary grounding pole C is reduced. When the resistance value is less than the second threshold value, the display unit 16 controls the display of the resistance value of the ground resistance Re of the measured grounded body E calculated by the measured grounded body grounded resistance calculating unit 55; The resistance value of the ground resistance Rp of the first auxiliary grounding pole P is at least a first threshold value, or at least one of the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C is at least a second threshold value. In order to avoid 0Ω, for example, “0.01Ω” or “0.001Ω” is used to limit the minimum value with the number of digits corresponding to the resolution of the grounding ohmmeter 1, and to measure the grounding object to be measured. The resistance value of the ground resistance Re of the measured ground body E calculated by the resistance calculator 55 , It controls the display on the display unit 16.

  Next, the ground resistance measurement process 1 executed by the ground resistance meter 1 will be described with reference to the flowchart of FIG.

  In the ground resistance measurement process 1, the user of the ground resistance meter 1 drives the first auxiliary grounding pole P and the second auxiliary grounding pole C into predetermined positions on the ground, and the connection terminal 31 has the first resistance The auxiliary grounding electrode P is connected, the connection terminal 32 is connected to the second auxiliary grounding electrode C, and the connection terminal 33 is connected to the grounding object E to be measured. In order to check and calibrate the operation of the ohmmeter 1, the operation is performed in a state where the connection terminal 31, the connection terminal 32, and the connection terminal 33 are short-circuited.

  In step S <b> 1, the control unit 14 calculates the resistance value of the composite ground resistance Rep by applying the AC voltage V <b> 1 between the measured ground body E and the first auxiliary ground pole P.

  Specifically, the switching control unit 52 of the control unit 14 controls the switching processing unit 18 to connect the first common contact com1 of the switch 41 to the connection terminal 33, and the second common contact com2 of the switch 42. Is connected to the connection terminal 31, and the third common contact com 3 of the switch 43 is connected to the switch 42. And the voltage application control part 51 applies the alternating voltage V1 between the to-be-measured body E and the 1st auxiliary | assistant ground pole P by making the signal generation part 11 output alternating voltage V1. At this time, a series circuit including the signal generation unit 11, the current measurement unit 12, the switch 41, the measured ground body E connected to the connection terminal 33, and the first auxiliary ground pole P connected to the connection terminal 31 is used. An alternating current I1 flows. The current measuring unit 12 measures the current value of the alternating current I1 and supplies it to the auxiliary grounding electrode ground resistance calculating unit 53 of the control unit 14. The voltage measuring unit 13 measures the voltage value of the AC voltage Vep applied between the measured ground body E and the first auxiliary grounding electrode P, and supplies it to the auxiliary grounding electrode grounding resistance calculating unit 53 of the control unit 14.

  Then, the auxiliary grounding electrode ground resistance calculating unit 53 of the control unit 14 calculates (measured voltage value / measured current value) based on the measured current value by the current measuring unit 12 and the measured voltage value by the voltage measuring unit 13. Thus, the resistance value of the combined ground resistance Rep is calculated and stored in the internal memory. Thereafter, the voltage application controller 51 of the controller 14 causes the signal generator 11 to stop outputting the AC voltage V1.

  In step S <b> 2, the control unit 14 calculates the resistance value of the combined ground resistance Rec by applying the AC voltage V <b> 1 between the measured ground body E and the second auxiliary ground pole C.

  Specifically, the switching control unit 52 of the control unit 14 controls the switching processing unit 18 to connect the first common contact com1 of the switch 41 to the connection terminal 33, and the second common contact com2 of the switch 42. Is connected to the connection terminal 32, and the third common contact com 3 of the switch 43 is connected to the switch 42. And the voltage application control part 51 applies the alternating voltage V1 between the to-be-measured body E and the 2nd auxiliary earthing pole C by making the signal generation part 11 output alternating voltage V1. At this time, a series circuit including the signal generation unit 11, the current measurement unit 12, the switch 41, the measured ground body E connected to the connection terminal 33, and the second auxiliary ground electrode C connected to the connection terminal 32 is provided. An alternating current I1 flows. The current measuring unit 12 measures the current value of the alternating current I1 and supplies it to the auxiliary grounding electrode ground resistance calculating unit 53 of the control unit 14. The voltage measuring unit 13 measures the voltage value of the AC voltage Vec applied between the measured ground E and the second auxiliary grounding electrode C, and supplies it to the auxiliary grounding electrode grounding resistance calculating unit 53 of the control unit 14.

  Then, the auxiliary grounding electrode ground resistance calculating unit 53 of the control unit 14 calculates (measured voltage value / measured current value) based on the measured current value by the current measuring unit 12 and the measured voltage value by the voltage measuring unit 13. Thus, the resistance value of the combined ground resistance Rec is calculated and stored in the internal memory. Thereafter, the applied voltage control unit 51 of the control unit 14 causes the signal generation unit 11 to stop outputting the AC voltage V1.

  In step S3, the control unit 14 applies the AC voltage V1 between the first auxiliary grounding electrode P and the second auxiliary grounding electrode C, and calculates the resistance value of the combined grounding resistance Rpc.

  Specifically, the switching control unit 52 of the control unit 14 controls the switching processing unit 18 to connect the first common contact com1 of the switch 41 to the connection terminal 31 and the second common contact com2 of the switch 42. Is connected to the connection terminal 32, and the third common contact com 3 of the switch 43 is connected to the switch 42. Then, the voltage application control unit 51 applies the AC voltage V1 between the first auxiliary grounding electrode P and the second auxiliary grounding electrode C by causing the signal generation unit 11 to output the AC voltage V1. At this time, a series including the signal generation unit 11, the current measurement unit 12, the switch 41, the first auxiliary grounding pole P connected to the connection terminal 31, and the second auxiliary grounding pole C connected to the connection terminal 32. An alternating current I1 flows through the circuit. The current measuring unit 12 measures the current value of the alternating current I1 and supplies it to the auxiliary grounding electrode ground resistance calculating unit 53 of the control unit 14. The voltage measuring unit 13 measures the voltage value of the AC voltage Vpc applied between the first auxiliary grounding electrode P and the second auxiliary grounding electrode C, and supplies the voltage value to the auxiliary grounding electrode grounding resistance calculating unit 53 of the control unit 14. To do.

  Then, the auxiliary grounding electrode ground resistance calculating unit 53 of the control unit 14 calculates (measured voltage value / measured current value) based on the measured current value by the current measuring unit 12 and the measured voltage value by the voltage measuring unit 13. Thus, the resistance value of the combined ground resistance Rpc is calculated and stored in the internal memory. Thereafter, the voltage application controller 51 of the controller 14 causes the signal generator 11 to stop outputting the AC voltage V1.

  In step S4, the control unit 14 calculates the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc.

  Specifically, the auxiliary grounding electrode ground resistance calculating unit 53 of the control unit 14 includes the resistance value of the combined grounding resistor Rep, the resistance value of the combined grounding resistor Rec stored in the internal memory by the processing of Step S1 to Step S3, Then, by using the resistance value of the combined grounding resistor Rpc, the simultaneous equations shown in the above-described formulas (1), (2), and (3) are solved to ground the first auxiliary grounding pole P. The resistance value of the resistor Rp and the resistance value of the grounding resistor Rc of the second auxiliary grounding pole C are calculated and supplied to the comparison unit 54.

  The measurement preparation is completed by the processing from step 1 to step S4 described above, and actual measurement is possible. At this time, for example, by displaying on the display unit 16 that measurement preparation is completed, the user is instructed to start actual measurement such as pressing the “Measure” button provided on the operation input unit 17, for example. The user may be prompted to perform an operation input.

  In step S <b> 5, the control unit 14 determines whether measurement start is instructed based on a signal supplied from the operation input unit 17 and indicating a user operation input. When it is determined in step S5 that the measurement start is not instructed, the process in step S5 is repeated until it is determined that the measurement start is instructed.

  If it is determined in step S5 that the measurement start has been instructed, in step S6, the control unit 14 applies the AC voltage V1 between the measured ground body E and the second auxiliary grounding electrode C, and the current measurement unit. 12 measures the current value of the alternating current I1 injected into the second auxiliary grounding pole C, and the voltage measuring unit 13 measures the voltage value between the measured ground E and the first auxiliary grounding pole P. .

  Specifically, the switching control unit 52 of the control unit 14 controls the switching processing unit 18 to connect the first common contact com1 of the switch 41 to the connection terminal 33, and the second common contact com2 of the switch 42. Is connected to the connection terminal 32, and the third common contact com 3 of the switch 43 is connected to the connection terminal 31. And the voltage application control part 51 applies the alternating voltage V1 between the to-be-measured body E and the 2nd auxiliary earthing pole C by making the signal generation part 11 output alternating voltage V1. The current measuring unit 12 measures the current value of the alternating current I1 injected into the second auxiliary grounding pole C and supplies it to the measured grounded body ground resistance calculating unit 55 of the control unit 14. The voltage measuring unit 13 measures the AC voltage Vep generated between the ground E to be measured and the first auxiliary grounding pole P due to the alternating current I1 flowing through the ground G. The measured grounding body grounding resistance calculation unit 55 is supplied.

  In step S7, the measured grounded body ground resistance calculating unit 55 of the control unit 14 calculates the current value injected into the second auxiliary grounded pole C obtained by the processing in step S6, and the measured grounded body E-1st. Using the voltage value Vep between the auxiliary grounding electrodes P, the resistance value of the grounding resistance Re of the grounded body E to be measured is obtained by the three-electrode method and supplied to the display control unit 56.

  In step S8, the comparison unit 54 of the control unit 14 determines that both the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc obtained by the process of step S4 are equal to or less than a predetermined value stored in the storage unit 15. Is determined, and the determination result is supplied to the display control unit 56. The predetermined value stored in the storage unit 15, that is, the first threshold value and the second threshold value described above may be the same value or different values, and the value is, for example, about 10Ω. It is preferable that

  In step S8, when it is determined that both the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc are equal to or less than the predetermined value stored in the storage unit 15, this measurement is performed on the ground resistance meter 1. Since it is presumed to be an operation check or calibration, in step S9, the display control unit 56 of the control unit 14 controls the display unit 16 to display the resistance value of the ground resistance Re of the measured ground E as it is. The process is terminated.

  If it is determined in step S8 that at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is not less than or equal to the predetermined value stored in the storage unit 15, this measurement is an actual measurement. Therefore, in step S10, the display control unit 56 of the control unit 14 controls the display unit 16 to limit the resistance value of the ground resistance Re of the measured ground body E to the minimum value. Display, and the process ends.

  Specifically, the display control unit 56 of the control unit 14 determines that at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is a predetermined value stored in the storage unit 15, that is, When it is not less than or equal to the first threshold value or the second threshold value, the display unit 16 is controlled even when the resistance value of the ground resistance Re of the measured ground body E obtained as a result of the calculation is “0Ω”. Then, for example, a value such as “0.01Ω” or “0.001Ω” is displayed according to the resolution.

  When actually measuring the resistance value of the grounding resistor Re of the grounded body E to be measured, the value of the grounding resistance Rp of the first auxiliary grounding resistor P or the value of the grounding resistance Rc of the second grounding resistor C is: It is assumed to take a certain value. On the other hand, in the calibration and operation check of the ground resistance meter 1, the connection terminals 31, 32, and 33 are short-circuited, so that the value of the ground resistance Rp of the first auxiliary ground resistance P or the second The value of the ground resistance Rc of the ground resistance C is assumed to be a value close to 0Ω.

  Therefore, by executing such processing, values such as “0.00Ω” and “0.000Ω” can be obtained depending on the accuracy of the ground resistance meter when measuring the resistance value of the ground resistance Re of the actual ground body E to be measured. Can be prevented from being displayed on the display unit 16, so that the user does not fall into a situation in which the measurement result of the resistance value of the grounding resistance Re of the grounded body E to be measured cannot be reported. When the connection terminals 31, 32, and 33 are short-circuited for calibration of the ground resistance meter 1 and operation check, values such as “0.00Ω” and “0.000Ω” can be displayed on the display unit 16. Therefore, it is not determined that there is a failure.

  Further, by such processing, the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode are obtained by combining the composite ground resistance Rep (= Re + Rp) and the composite ground resistance Rec (= Re + Rc). It becomes possible to obtain more accurately without using.

  By the way, the test of whether or not the product specification is satisfied in accordance with the international standard IEC61557-5 of the ground resistance meter is performed by the resistance value of the ground resistance Rp of the first auxiliary ground pole P and the ground of the second auxiliary ground pole C. It is determined to be executed under the condition that the resistance value of the resistor Rc is within a range of 100Ω ± 3%. Therefore, the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the grounding resistance Rc of the second auxiliary grounding pole C are not misrecognized as a failure in the test of whether or not the product specifications are satisfied. For example, when at least one of the resistance values is within a predetermined range defined in a test condition such as 100Ω ± 3%, the calculated resistance value of the grounding resistance Re of the measured ground body E is It is preferable to display without limiting the minimum value.

  Next, referring to FIGS. 4, 5, and 6, a second example of a grounding ohmmeter that can limit the minimum value of the measurement result as necessary based on the state of the auxiliary grounding pole. The grounding resistance meter 71 will be described.

  In addition to the case where the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C are both equal to or less than a predetermined value, the ground resistance meter 71 When at least one of the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C is within a predetermined range such as 100Ω ± 3%, for example The calculated resistance value of the ground resistance Re of the measured ground body E can be displayed without limiting the minimum value, and the resistance value of the ground resistance Rp of the first auxiliary ground pole P and the first resistance value can be displayed. At least one of the resistance values of the ground resistance Rc of the two auxiliary grounding poles C is equal to or greater than a predetermined value, and the resistance value of the grounding resistance Rp of the first auxiliary grounding pole P and the second auxiliary grounding pole C Both of the resistance values of the ground resistance Rc are, for example, 10 When the value is not within a predetermined range such as 0Ω ± 3%, the calculated resistance value of the ground resistance Re of the measured ground E can be displayed with its minimum value being limited. Hereinafter, as an example, a case where the predetermined range is 100Ω ± 3% will be described.

  The configuration of the ground resistance meter 71 will be described with reference to FIG.

  In addition, the same number is attached | subjected to the part same as the ground resistance meter 1 of FIG. 1, and the detailed description is abbreviate | omitted. That is, the ground resistance meter 71 of FIG. 4 is provided with a control unit 81 instead of the control unit 14. The other configuration is the same as that of the ground resistance meter 1 shown in FIG.

  The control unit 81 includes, for example, an arithmetic element such as a CPU, an internal memory, and the like, receives a signal corresponding to a user operation input from the operation input unit 17, and is supplied from the current measurement unit 12. Based on the measured current value and the measured voltage value supplied from the voltage measuring unit 13, a process including a ground resistance measuring process 2 described later with reference to FIG. 6 is executed. In this case, the internal memory functions as a work memory for the CPU.

  That is, the control unit 81 controls the signal generation unit 11 and the switching processing unit 18 to connect the ground resistance Rp of the first auxiliary grounding pole P connected to the connection terminal 31 and the connection terminal 32. After measuring the grounding resistance Rc of the two auxiliary grounding poles C, the grounding resistance Re of the measured ground body E connected to the connection terminal 33 is measured by the three-electrode method. Then, in addition to the case where the ground resistance Rp of the first auxiliary grounding pole P and the grounding resistance Rc of the second auxiliary grounding pole C are both lower than a predetermined value, the control unit 81 When at least one of the resistance value of the grounding resistance Rp of the auxiliary grounding electrode P and the resistance value of the grounding resistance Rc of the second auxiliary grounding electrode C is within a range of 100Ω ± 3%, The measured value of the resistance Re is displayed on the display unit 16, and at least one of the ground resistance Rp of the first auxiliary grounding pole P and the grounding resistance Rc of the second auxiliary grounding pole C is higher than a predetermined value, and When the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C are not within the range of 100Ω ± 3%, The measured value of ground resistance Re is prohibited from being displayed as 0Ω on the display unit 16. For example, the minimum value of the measurement result is limited to a value such as “0.01Ω” and the measured value of the grounding resistance Re of the grounded body E to be measured is displayed on the display unit 16.

  Details of the functions of the control unit 81 will be described with reference to FIG.

  FIG. 4 is a functional block diagram for explaining functions of the control unit 81 of the ground ohmmeter 71 of FIG. 2 that are the same as those of the control unit 14 in FIG. 2 are assigned the same reference numerals, and detailed descriptions thereof are omitted. That is, the control unit 81 is provided with a comparison unit 91 instead of the comparison unit 54, and a display control unit 92 instead of the display control unit 56. Other functions are the same as those of the control unit 14 shown in FIG.

  The comparison unit 91 compares the resistance value of the ground resistance Rp of the first auxiliary ground electrode P calculated by the auxiliary ground electrode ground resistance calculation unit 53 with the first threshold value stored in the storage unit 15. The resistance value of the ground resistance Rc of the second auxiliary earthing pole C calculated by the auxiliary earthing pole earthing resistance calculating unit 53 is compared with the second threshold value stored in the storage unit 15, and the comparison result is obtained. This is supplied to the display control unit 92. Further, the comparison unit 91 calculates the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C calculated by the auxiliary grounding pole grounding resistance calculation unit 53. , 100Ω ± 3%, and the comparison result is supplied to the display control unit 92.

  Based on the comparison result obtained by the processing of the comparison unit 91, the display control unit 92 has a resistance value of the ground resistance Rp of the first auxiliary grounding pole P that is equal to or lower than the first threshold value and the second auxiliary grounding. The resistance value of the ground resistance Rc of the pole C is equal to or smaller than the second threshold value, or the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C When at least one of them is within a range of 100Ω ± 3%, the resistance value of the grounding resistance Re of the measured grounded body E calculated by the measured grounded body grounded resistance calculating unit 55 is displayed on the display unit 16. Control the display. Further, the display control unit 92 determines whether the resistance value of the ground resistance Rp of the first auxiliary ground pole P is equal to or lower than the first threshold based on the comparison result obtained by the processing of the comparison unit 91. The resistance value of the ground resistance Rc of the ground pole C is at least one of the second threshold value and the resistance value of the ground resistance Rp of the first auxiliary ground pole P and the second auxiliary ground pole C. Depending on the resolution of the ground resistance meter 71, for example, “0.01Ω” or “0.001Ω” so that the resistance value of the ground resistance Rc is not 0Ω when both are not within the range of 100Ω ± 3%. By limiting the minimum value with the number of digits, the display unit 16 controls the display of the resistance value of the grounding resistance Re of the grounding object E measured by the grounding object grounding resistance calculation unit 55.

  The test of whether or not the product specifications are satisfied in accordance with the international standard IEC61557-5 of the ground resistance meter is performed by the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the grounding resistance Rc of the second auxiliary grounding pole C. The resistance value is determined so as to be executed under the condition that the resistance value is within a range of 100Ω ± 3%. Therefore, in the ground resistance meter 71, the resistance value of the grounding resistance Rp of the first auxiliary grounding pole P and the second auxiliary resistance 71 are not misrecognized as a failure in the test of whether or not the product specifications are satisfied. When at least one of the resistance values of the grounding resistance Rc of the grounding pole C is within the range of 100Ω ± 3%, the grounding resistance Re of the measured grounding body E calculated by the measured grounding body grounding resistance calculating unit 55 The resistance value is displayed on the display unit 16 without limiting the minimum value. In other words, in the ground resistance meter 71, at least one of the resistance value of the ground resistance Rp of the first auxiliary ground pole P and the resistance value of the ground resistance Rc of the second auxiliary ground pole C is 100Ω ± 3%. If it is within the range and “0.00Ω” is the measurement result, the measurement value is displayed on the display unit 16 as it is.

  Next, the ground resistance measurement process 2 executed by the ground resistance meter 71 will be described with reference to the flowchart of FIG.

  In the ground resistance measurement process 2, the user of the ground resistance meter 71 drives the first auxiliary grounding pole P and the second auxiliary grounding pole C into predetermined positions on the ground, and the connection terminal 31 has the first resistance The auxiliary grounding electrode P is connected, the connection terminal 32 is connected to the second auxiliary grounding electrode C, and the connection terminal 33 is connected to the grounding object E to be measured. In order to check or calibrate the operation of the ohmmeter 71, the test is performed in a state where the connection terminal 31, the connection terminal 32, and the connection terminal 33 are short-circuited or whether the specification of the product is satisfied. Therefore, the process is executed under the condition that the resistance value of the ground resistance Rp of the first auxiliary grounding pole P and the resistance value of the grounding resistance Rc of the second auxiliary grounding pole C are within a range of 100Ω ± 3%.

  In step S21 to step S27, the same process as step S1 to step S7 of the ground resistance measurement process 1 described with reference to FIG. 3 is executed.

  That is, in step S21, the control unit 81 calculates the resistance value of the combined grounding resistor Rep by applying the AC voltage V1 between the measured ground body E and the first auxiliary grounding pole P.

  In step S <b> 22, the control unit 81 applies the AC voltage V <b> 1 between the measured ground body E and the second auxiliary grounding pole C, and calculates the resistance value of the combined grounding resistance Rec.

  In step S23, the control unit 81 applies the AC voltage V1 between the first auxiliary grounding pole P and the second auxiliary grounding pole C, and calculates the resistance value of the combined grounding resistance Rpc.

  In step S24, the control unit 81 calculates the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc.

  In step S <b> 25, the control unit 81 determines whether measurement start is instructed based on a signal supplied from the operation input unit 17 and indicating a user operation input. If it is determined in step S25 that the measurement start is not instructed, the process in step S25 is repeated until it is determined that the measurement start is instructed.

  If it is determined in step S25 that the measurement start has been instructed, in step S26, the control unit 81 applies the AC voltage V1 between the measured ground body E and the second auxiliary grounding electrode C, and the current measurement unit. 12 measures the current value of the alternating current I1 injected into the second auxiliary grounding pole C, and the voltage measuring unit 13 measures the voltage value between the measured ground E and the first auxiliary grounding pole P. .

  In step S27, the measured grounded body ground resistance calculating unit 55 of the control unit 81 calculates the current value injected into the second auxiliary grounded pole C obtained by the process of step S6, and the measured grounded body E-first. Using the voltage value Vep between the auxiliary grounding electrodes P, the resistance value of the grounding resistance Re of the grounded body E to be measured is obtained by the three-electrode method and supplied to the display control unit 92.

  In step S28, the comparison unit 91 of the control unit 81 determines whether the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc obtained by the process of step S4 are both stored in the storage unit 15. It is determined whether or not the value is equal to or less than the value, and the determination result is supplied to the display control unit 92. The predetermined value stored in the storage unit 15, that is, the first threshold value and the second threshold value described above may be the same value or different values, and the value is, for example, about 10Ω. It is preferable that

  If it is determined in step S28 that at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is not less than or equal to the predetermined value stored in the storage unit 15, the control is performed in step S29. The display control unit 92 of the unit 81 determines whether or not at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is within a range of 100Ω ± 3%.

  If it is determined in step S29 that at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is within the range of 100Ω ± 3%, the process proceeds to step S31.

  If it is determined in step S29 that both of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc are not within the range of 100Ω ± 3%, this measurement is estimated to be an actual measurement. In step S30, the display control unit 92 of the control unit 81 controls the display unit 16 to display the resistance value of the grounding resistance Re of the grounded body E to be measured while limiting the minimum value, and the processing is completed. The

  Specifically, the display control unit 92 of the control unit 81 controls the display unit 16 even when the resistance value of the ground resistance Re of the measured ground E obtained as a result of the calculation is “0Ω”. Then, for example, a value such as “0.01Ω” or “0.001Ω” is displayed according to the resolution.

  In step S28, when it is determined that the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc are both equal to or less than the predetermined value stored in the storage unit 15, this measurement is performed by the ground resistance meter 71. Presumed to be operation check and calibration. If it is determined in step S29 that at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is within the range of 100Ω ± 3%, whether or not the product specification is satisfied. May have been tested. Therefore, in step S31, the display control unit 92 of the control unit 81 controls the display unit 16 to display the resistance value of the ground resistance Re of the measured ground body E as it is, and the processing is ended.

  When actually measuring the resistance value of the grounding resistor Re of the grounded body E to be measured, the value of the grounding resistance Rp of the first auxiliary grounding resistor P or the value of the grounding resistance Rc of the second grounding resistor C is: It is assumed to take a certain value. On the other hand, in the calibration and operation check of the ground resistance meter 71, the connection terminals 31, 32, and 33 are short-circuited, so the value of the ground resistance Rp of the first auxiliary ground resistance P or the second The value of the ground resistance Rc of the ground resistance C is assumed to be a value close to 0Ω. In addition, when at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is within a range of 100Ω ± 3%, a test is performed to determine whether or not the product specifications are satisfied. there is a possibility.

  Therefore, by executing such processing, values such as “0.00Ω” and “0.000Ω” can be obtained depending on the accuracy of the ground resistance meter when measuring the resistance value of the ground resistance Re of the actual ground body E to be measured. Can be prevented from being displayed on the display unit 16, so that the user does not fall into a situation in which the measurement result of the resistance value of the grounding resistance Re of the grounded body E to be measured cannot be reported. When the connection terminals 31, 32, and 33 are short-circuited in the calibration or operation check of the ground resistance meter 71, the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc are within the range of 100Ω ± 3%. When a test is performed to determine whether or not the product specifications are satisfied, values such as “0.00Ω” and “0.000Ω” can be displayed on the display unit 16, so that it is determined as a failure. There is nothing.

  Further, by such processing, the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode are obtained by combining the composite ground resistance Rep (= Re + Rp) and the composite ground resistance Rec (= Re + Rc). It becomes possible to obtain more accurately without using.

  Here, in step S28, it is determined whether or not at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is equal to or less than a predetermined value stored in the storage unit 15. In step S29, it has been described that it is determined whether or not at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is within the range of 100Ω ± 3%. After determining whether at least one of the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc is within a range of 100Ω ± 3%, the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc are determined. Needless to say, it may be determined whether at least one of the resistance values is equal to or less than a predetermined value stored in the storage unit 15.

  Further, without determining whether at least one of the resistance value of the grounding resistor Rp and the resistance value of the grounding resistor Rc is equal to or less than a predetermined value stored in the storage unit 15, The resistance value of the ground resistance Rp and the ground resistance Rc are determined only depending on the determination result of whether or not at least one of the resistance value of the resistance Rp and the resistance value of the ground resistance Rc is within the range of 100Ω ± 3%. The resistance value of the grounding resistor Re of the grounded body E to be measured may be displayed with a minimum value limited, unless at least one of the resistance values is within a range of 100Ω ± 3%. .

  Further, here, as an example of the predetermined range, 100Ω ± 3% has been described, but it is determined whether or not the resistance value of the grounding resistor Re of the grounded body E to be measured is displayed with a minimum value limited. The predetermined range for performing the above is not limited to this, and it goes without saying that any other range of values may be used.

  As described above, an AC voltage is generated, and a current value of a current flowing in a predetermined circuit is measured by the generated AC voltage, and a voltage value of a voltage applied to the predetermined circuit is measured by the generated AC voltage. Then, by switching the circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected, based on the measured current value and the measured voltage value in a predetermined circuit Thus, the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode are calculated. Then, in a predetermined circuit, the ground resistance value of the measured ground body is calculated based on the measured current value and the measured voltage value. Then, the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode are compared with a predetermined value, and based on the comparison result, the calculated ground resistance value of the measured grounding body The display is controlled or the minimum value is limited so that the display of the ground resistance value of the measured grounding body is controlled. The minimum result can be limited.

  Further, the ground resistance value of the first auxiliary grounding electrode is compared with a predetermined first value, and the grounding resistance value of the second auxiliary grounding electrode is compared with a predetermined second value. On the basis of the ground resistance value of the first auxiliary grounding electrode is less than the predetermined first value and the grounding resistance value of the second auxiliary grounding electrode is less than the predetermined second value. The display of the ground resistance value of the measured grounded body is controlled, and the ground resistance value of the first auxiliary ground electrode is greater than or equal to a predetermined first value, or the ground resistance value of the second auxiliary ground electrode is When it is at least one of the predetermined second value and above, the minimum value is limited, and the display of the calculated grounding resistance value of the grounded object to be measured is controlled. Even if the resistance value of the grounding resistance Re of the obtained grounded object E to be measured is “0Ω”, the actual measured object At the time of measuring the resistance value of the grounding resistor Re of the grounding body E, a value whose minimum value is limited according to the resolution, that is, a value such as “0.01Ω” or “0.001Ω”, for example, is displayed. In the case where the connection terminal 31, the connection terminal 32, and the connection terminal 33 are short-circuited to check whether or not the ground resistance meter 71 has failed or to perform calibration, “0” is displayed. A value such as “.00Ω” or “0.000Ω” can be displayed on the display unit 16.

  The ground resistance value of the first auxiliary grounding electrode is compared with a predetermined first value, the grounding resistance value of the second auxiliary grounding electrode is compared with a predetermined second value, and the first The ground resistance value of the auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode are compared with a predetermined range, and based on the comparison result, the ground resistance value of the first auxiliary ground electrode is a predetermined first value. And the ground resistance value of the second auxiliary ground electrode is less than a predetermined second value, or the ground resistance value of the first auxiliary ground electrode and the ground resistance of the second auxiliary ground electrode When at least one of the values is within a predetermined range, the display of the calculated ground resistance value of the measured grounded body is controlled, and the ground resistance value of the first auxiliary ground electrode is a predetermined first value. Or at least whether the ground resistance value of the second auxiliary grounding electrode is equal to or greater than a predetermined second value. If both of the ground resistance value of the first auxiliary grounding electrode and the grounding resistance value of the second auxiliary grounding electrode calculated by the first calculation means are not within the predetermined range, the minimum value And the display of the ground resistance value of the measured ground body calculated by the second calculation means is controlled, so that the resistance of the ground resistance Re of the measured ground body E obtained as a result of the calculation is controlled. Even when the value is “0Ω”, when measuring the resistance value of the ground resistance Re of the actual ground E to be measured, the minimum value is limited according to the resolution, that is, for example, “ A value such as “0.01Ω” or “0.001Ω” is displayed on the display unit 16, and the connection terminal 31, the connection terminal 32, and the connection terminal 33 are short-circuited, and the ground resistance meter 71 is not broken. Check if it is In the case where the resistance value of Rp and the resistance value of grounding resistance Rc are tested within a predetermined range determined by a test condition such as 100Ω ± 3%, for example, whether or not the product specification is satisfied. , “0.00Ω” or “0.000Ω” can be displayed on the display unit 16.

  The ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode are compared with a predetermined range, and the ground resistance value of the first auxiliary ground electrode and the ground of the second auxiliary ground electrode are compared. When at least one of the resistance values is within a predetermined range, the display of the calculated ground resistance value of the measured ground body is controlled, and the first auxiliary ground electrode calculated by the first calculation means is controlled. When both the ground resistance value and the ground resistance value of the second auxiliary ground electrode are not within the predetermined range, the minimum value is limited, and the ground resistance value of the measured ground body calculated by the second calculation means is limited. When the display is controlled, even if the resistance value of the ground resistance Re of the measured ground body E obtained as a result of the calculation is “0Ω”, the actual ground resistance of the measured ground body E When measuring the resistance value of Re, the minimum value depends on the resolution. A limited value, for example, a value such as “0.01Ω” or “0.001Ω” is displayed on the display unit 16, and the resistance value of the ground resistance Rp and the resistance value of the ground resistance Rc are, for example, When a test is performed to determine whether the product specifications are satisfied within a predetermined range set for test conditions such as 100Ω ± 3%, values such as “0.00Ω” and “0.000Ω” Can be displayed on the display unit 16.

  Therefore, when the connection terminal 31, the connection terminal 32, and the connection terminal 33 are short-circuited to check whether the ground ohmmeter 71 has failed, when calibration is performed, or whether the product specifications are satisfied. In the case where the test of whether or not the test is performed, “0.00Ω” is determined by the accuracy of the ground resistance meter when measuring the resistance value of the ground resistance Re of the actual grounded body E without being erroneously recognized as a failure. And a value such as “0.000Ω” can be prevented from being displayed on the display unit 16, so that the user cannot report the measurement result of the resistance value of the grounding resistance Re of the grounded body E to be measured. You will not fall into

  Further, the first resistance ground and the second auxiliary grounding electrode are calculated in the first and second grounding resistance values, and the first and second grounding resistance values of the measured grounding body are calculated. Since the switch is controlled so that the circuit to which the connection terminal, the second connection terminal, and the third connection terminal are connected is different, the ground resistance value of the first auxiliary ground electrode, In addition, the ground resistance value of the second auxiliary ground electrode can be obtained more accurately without using the composite ground resistance Rep (= Re + Rp) and the composite ground resistance Rec (= Re + Rc).

  The series of processes described above can be executed by hardware or can be executed by software. When a series of processing is executed by software, a program constituting the software executes various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a program recording medium in a general-purpose personal computer or the like.

  The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

  The embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

1 ... Ground resistance meter,
11 ... Signal generator (signal generator),
12: Current measuring unit (current measuring means),
13: Voltage measuring unit (voltage measuring means),
14 ... control unit,
15 ... storage part,
16 ... display part,
17 ... operation input part,
18 ... switching processing part (switching means),
31, 32, 33 ... connection terminals,
41, 42, 43 ... switches,
51 ... Voltage application control unit,
52. Switching control unit (switching control means),
53 ... Auxiliary earthing pole earthing resistance calculating part (first calculating means),
54. Comparison unit (comparison means)
55: Grounding resistance measurement unit to be measured (second calculation means),
56. Display control unit (display control means)
71: Ground resistance meter,
81. Control unit,
91 ... comparison unit (comparison means),
92: Display control unit (display control means)

Claims (9)

A first connection terminal connected to the first auxiliary grounding electrode; a second connection terminal connected to the second auxiliary grounding electrode; and a third connection terminal connected to the measured grounding body. In the ground resistance meter that measures the ground resistance of the grounded object to be measured,
Signal generating means for generating an alternating voltage;
Current measuring means for measuring a current value of a current flowing in a predetermined circuit by the AC voltage generated by the signal generating means;
Voltage measuring means for measuring a voltage value of a voltage applied to a predetermined circuit by the AC voltage generated by the signal generating means;
Switching means for switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected;
Switching control means for controlling switching of the circuit by the switching means;
Based on the current value measured by the current measuring means and the voltage value measured by the voltage measuring means in the predetermined circuit switched by the switching means, the first auxiliary grounding electrode is grounded. A first calculation means for calculating a resistance value and a ground resistance value of the second auxiliary ground electrode;
In the predetermined circuit switched by the switching means, based on the current value measured by the current measuring means and the voltage value measured by the voltage measuring means, the ground resistance value of the grounded body to be measured A second calculating means for calculating
Comparing means for comparing the ground resistance value of the first auxiliary grounding electrode and the grounding resistance value of the second auxiliary grounding electrode calculated by the first calculating means with a predetermined value;
Based on the processing result of the comparison means, the display of the ground resistance value of the grounded body to be measured calculated by the second calculation means is controlled, or the minimum value is limited and the second calculation is performed. And a display control means for controlling the display of the ground resistance value of the measured ground body calculated by the means. The ground resistance meter according to claim 1,
The comparison means compares the ground resistance value of the first auxiliary grounding pole calculated by the first calculation means with a predetermined first value, and the first calculation means calculated by the first calculation means. Comparing the ground resistance value of the two auxiliary ground electrodes with a predetermined second value;
The display means has a ground resistance value of the first auxiliary grounding electrode less than a predetermined first value and a grounding resistance value of the second auxiliary grounding electrode based on the processing result of the comparing means. Is less than a predetermined second value, the display of the grounding resistance value of the measured grounding body calculated by the second calculating means is controlled, and the grounding resistance value of the first auxiliary grounding electrode is controlled. If it is at least one of a predetermined first value and a ground resistance value of the second auxiliary grounding electrode is a predetermined second value or more, the minimum value is limited, and the first A ground resistance meter characterized by controlling the display of the ground resistance value of the grounded body to be measured calculated by the calculating means of 2. The ground resistance meter according to claim 1,
The comparison means compares the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode calculated by the first calculation means with a predetermined range;
The display control means is configured to calculate the ground resistance value of the first auxiliary ground electrode and the ground resistance of the second auxiliary ground electrode based on the processing result of the comparison means or by the first calculation means. When at least one of the values is within the predetermined range, the display of the ground resistance value of the measured ground body calculated by the second calculation unit is controlled and calculated by the first calculation unit. Further, when both the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode are not within the predetermined range, the minimum value is limited by the second calculation means. Controlling the display of the calculated grounding resistance value of the measured grounded body. The ground resistance meter according to claim 3,
The predetermined range is 100Ω ± 3%. The ground resistance meter according to claim 1,
The comparison means compares the ground resistance value of the first auxiliary grounding pole calculated by the first calculation means with a predetermined first value, and the first calculation means calculated by the first calculation means. The ground resistance value of the two auxiliary grounding poles is compared with a predetermined second value, and the grounding resistance value of the first auxiliary grounding pole calculated by the first calculating means and the second auxiliary grounding are calculated. Compare the ground resistance value of the pole with the predetermined range,
The display control means has a ground resistance value of the first auxiliary grounding pole calculated by the first calculation means based on a processing result of the comparison means that is less than a predetermined first value, and When the grounding resistance value of the second auxiliary grounding pole calculated by the first calculating unit is less than a predetermined second value, or the first auxiliary unit calculated by the first calculating unit When at least one of the ground resistance value of the ground electrode and the ground resistance value of the second auxiliary ground electrode is within the predetermined range, the ground resistance of the measured ground body calculated by the second calculation means The display of the value is controlled, and the ground resistance value of the first auxiliary grounding electrode is greater than or equal to a predetermined first value, or the grounding resistance value of the second auxiliary grounding electrode is greater than or equal to a predetermined second value. And at least one of the first and second When both the ground resistance value of the first auxiliary grounding electrode and the ground resistance value of the second auxiliary grounding electrode calculated by the calculating means are not within the predetermined range, the minimum value is limited, and the first A ground resistance meter characterized by controlling the display of the ground resistance value of the grounded body to be measured calculated by the calculating means of 2. The ground resistance meter according to claim 5,
The predetermined range is 100Ω ± 3%. The ground resistance meter according to claim 1,
In the switching control means, the first calculation means calculates the ground resistance value of the first auxiliary ground electrode and the ground resistance value of the second auxiliary ground electrode, and the second calculation The circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected is different from the case where the ground resistance value of the measured ground body is calculated by the means. The ground resistance meter is characterized by controlling the switching means. A first connection terminal connected to the first auxiliary grounding electrode; a second connection terminal connected to the second auxiliary grounding electrode; and a third connection terminal connected to the measured grounding body. In the ground resistance measuring method of the ground resistance meter that measures the ground resistance of the grounding object to be measured,
A first switching step of switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected;
A first signal generating step for generating an alternating voltage;
A first current measurement step of measuring a current value of a current flowing in a predetermined circuit by an AC voltage generated by the processing of the first signal generation step;
A first voltage measuring step of measuring a voltage value of a voltage applied to a predetermined circuit by an alternating voltage generated by the processing of the first signal generating step;
In the predetermined circuit switched by the processing of the first switching step, the current value measured by the processing of the first current measuring step and the measured by the processing of the first voltage measuring step A first calculation step of calculating a ground resistance value of the first auxiliary ground electrode and a ground resistance value of the second auxiliary ground electrode based on a voltage value;
A second switching step for switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected;
A second signal generating step for generating an alternating voltage;
A second current measurement step of measuring a current value of a current flowing in a predetermined circuit by an AC voltage generated by the processing of the second signal generation step;
A second voltage measuring step of measuring a voltage value of a voltage applied to a predetermined circuit by the alternating voltage generated by the processing of the second signal generating step;
Based on the current value measured by the second current measurement step and the voltage value measured by the second voltage measurement step in the predetermined circuit switched by the processing of the second switching step. A second calculation step of calculating a ground resistance value of the measured ground body;
A comparison step of comparing the ground resistance value of the first auxiliary grounding pole and the grounding resistance value of the second auxiliary grounding pole calculated by the first calculation step with a predetermined value;
Based on the processing result of the comparison step, the display of the ground resistance value of the measured ground body calculated by the second calculation step is controlled, or the minimum value is limited, and the second calculation is performed. A display control step of controlling display of the ground resistance value of the grounded object to be measured calculated in the step. A first connection terminal connected to the first auxiliary grounding electrode; a second connection terminal connected to the second auxiliary grounding electrode; and a third connection terminal connected to the measured grounding body. And a program executed by a ground ohmmeter that measures the ground resistance of the measured ground body,
A first switching step of switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected;
A first signal generating step for generating an alternating voltage;
A first current measurement step of measuring a current value of a current flowing in a predetermined circuit by an AC voltage generated by the processing of the first signal generation step;
A first voltage measuring step of measuring a voltage value of a voltage applied to a predetermined circuit by an alternating voltage generated by the processing of the first signal generating step;
In the predetermined circuit switched by the processing of the first switching step, the current value measured by the processing of the first current measuring step and the measured by the processing of the first voltage measuring step A first calculation step of calculating a ground resistance value of the first auxiliary ground electrode and a ground resistance value of the second auxiliary ground electrode based on a voltage value;
A second switching step for switching a circuit to which the first connection terminal, the second connection terminal, and the third connection terminal are connected;
A second signal generating step for generating an alternating voltage;
A second current measurement step of measuring a current value of a current flowing in a predetermined circuit by an AC voltage generated by the processing of the second signal generation step;
A second voltage measuring step of measuring a voltage value of a voltage applied to a predetermined circuit by the alternating voltage generated by the processing of the second signal generating step;
Based on the current value measured by the second current measurement step and the voltage value measured by the second voltage measurement step in the predetermined circuit switched by the processing of the second switching step. A second calculation step of calculating a ground resistance value of the measured ground body;
A comparison step of comparing the ground resistance value of the first auxiliary grounding pole and the grounding resistance value of the second auxiliary grounding pole calculated by the first calculation step with a predetermined value;
Based on the processing result of the comparison step, the display of the ground resistance value of the measured ground body calculated by the second calculation step is controlled, or the minimum value is limited, and the second calculation is performed. A display control step for controlling display of a grounding resistance value of the grounded body to be measured calculated in the step.

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