CN112904087A - Device and method for measuring resistance of double-end grounding loop and resistance of grounding grid - Google Patents
Device and method for measuring resistance of double-end grounding loop and resistance of grounding grid Download PDFInfo
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- CN112904087A CN112904087A CN202110080374.9A CN202110080374A CN112904087A CN 112904087 A CN112904087 A CN 112904087A CN 202110080374 A CN202110080374 A CN 202110080374A CN 112904087 A CN112904087 A CN 112904087A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
- G01R27/205—Measuring contact resistance of connections, e.g. of earth connections
Abstract
The invention discloses a device and a method for measuring resistance of a double-end grounding loop and resistance of a grounding grid, wherein the device comprises a measuring device for outputting constant current to a measuring loop, the measuring loop comprises a measured branch, a grounding bar and the grounding grid which are connected in series, a sampling clamp for measuring voltage signals of the grounding bar is arranged on the grounding bar, and the output end of the sampling clamp is connected with the input end of the measuring device; the method comprises the steps of measuring the voltage of the grounding bar by using a sampling clamp and a measuring device, obtaining a shunt proportion according to the voltage proportion, and further calculating the resistance of a branch to be measured. The invention can accurately measure the actual flowing current value of each branch without dismantling the grounding wire, thereby more accurately measuring the loop resistance or the ground screen resistance of each branch, and improving the detection accuracy and the working efficiency.
Description
Technical Field
The invention relates to the technical field of power supply detection, in particular to a device and a method for measuring double-end grounding loop resistance and grounding grid resistance.
Background
With the popularization of GIS (gas insulated substation), a disconnecting switch, a circuit breaker and the like can automatically enter a double-end grounding state under a power failure maintenance state, and due to the fact that a plurality of current loops are arranged, the traditional loop resistance measurement has the situation of overlarge error; in the measurement of the resistance of the grounding grid connected to the ground at multiple points, a plurality of current branches are formed, and the similar situation occurs.
For a double-end grounded loop resistor or a ground network resistor, a plurality of branches are connected in parallel due to double-end grounding, and the key point is to obtain the current value of each branch for measuring the resistance value of each branch, there are two schemes at present: 1) using a large current for measurement: the method is suitable for the difference of at least 1 magnitude order of the parallel branch resistance, and the measuring result is close to the measured branch resistance by using 300A or more current; whether the application condition is satisfied or not is not easy to judge, the measurement result always has errors, and the application range is limited. 2) Measuring the current of one or more branches by using an AC/DC current clamp so as to obtain the actual current value of the measured branch and further calculate the resistance value; the measurement accuracy is limited by the measurement accuracy of the current clamp, even some fields can not provide the measurement part of the current clamp, or the number of branches is too large, and the simultaneous measurement of the current clamp becomes complicated and difficult to realize.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a device and a method for measuring a double-end grounding loop resistor and a ground grid resistor, which can accurately measure the actual flowing current value of each branch without dismantling a grounding wire, thereby more accurately measuring the loop resistor or the ground grid resistor of each branch and improving the detection accuracy and the working efficiency.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows.
The utility model provides a bi-polar ground circuit resistance and counterpoise resistance measuring device, includes to measuring circuit output constant current's measuring device, measures the return circuit and includes series connection's branch road, ground connection row and counterpoise being surveyed, be provided with the sampling anchor clamps of measuring ground connection row voltage signal on the ground connection row, the input of measuring device is connected to the output of sampling anchor clamps.
The measuring device for the resistance of the double-end grounding loop and the resistance of the grounding grid comprises a microcontroller, a constant current source, a current acquisition module and a voltage acquisition module; the output end of the microcontroller is connected with the input end of the constant current source, and two current output clamps of the constant current source are respectively clamped at one end of the tested branch and the middle part of the grounding bar; the output ends of the current acquisition module and the voltage acquisition module are respectively connected with the input end of the microcontroller, and the microcontroller calculates the resistance of the measured branch according to the output constant current, the acquired voltage at the two ends of the measured branch and the actual current value in the measurement loop.
The measuring device further comprises a human-computer interaction module consisting of a liquid crystal display and a key board, and the human-computer interaction module is communicated with the microcontroller.
Above-mentioned bi-polar ground return circuit resistance and counterpoise resistance measuring device, the sampling anchor clamps include the casing, and the fixed magnet that is convenient for adsorb on the ground connection row that is provided with on the bottom face of casing, is located and sets up a scalable probe on the casing bottom face of magnet both sides respectively, be provided with the input in the casing and be connected with scalable probe, be used for signal conversion's circuit board, the voltage signal line on the casing is fixed to the output connection one end of circuit board.
A method for measuring the resistance of a double-end grounding loop and the resistance of a grounding grid is realized based on the measuring device and specifically comprises the following steps:
A. the measured branch, the grounding bar and the ground network are connected in series to form a measuring loop;
B. respectively clamping two current output clamps of a measuring host at one end of a measured branch and the middle part of a grounding bar, adsorbing a sampling clamp on the grounding bar, and connecting a voltage signal wire to a measuring device;
C. the measuring device outputs constant current to the measuring loop, and collects the current value of the measured branch, the voltage values at two ends of the measured branch, the voltage value from the current injection point on the grounding bar to the endpoint of the measured branch and the voltage value from the current injection point on the grounding bar to the endpoint of the grounding grid;
D. and C, calculating the resistance of the branch to be tested according to the data collected in the step C.
In the step B, two sampling clamps are used for respectively collecting voltages of the upper part and the lower part of the grounding bar, or one clamp is used for respectively measuring the voltages of the upper part and the lower part so as to calculate the shunt ratio.
Due to the adoption of the technical scheme, the technical progress of the invention is as follows.
The invention is used for measuring the loop resistance of double-end grounding and the earth screen resistance of double-end grounding, can accurately measure the actually flowing current value of each branch without using multiple heavy current or current clamp under the condition of not removing the grounding wire, further more accurately measure the loop resistance or the earth screen resistance of each branch, and greatly improves the detection accuracy and the working efficiency.
Drawings
FIG. 1 is a functional block diagram of the present invention;
FIG. 2 is a block diagram of a test apparatus according to the present invention;
FIG. 3 is a schematic diagram of the measurement of the present invention;
FIG. 4 is a schematic view of the current flow during the measurement process of the present invention;
FIG. 5 is a schematic view of a sampling fixture according to the present invention;
FIG. 6 is a schematic diagram of the current flow when two sampling jigs are used to measure the calibration factor.
Wherein: 1. the method comprises the steps of measuring a resistance of a circuit to be measured, 2, a sampling clamp, 21, a shell, 22, a magnet, 23, a telescopic probe, 24, a voltage signal line, 3, a measuring device, 4, a ground grid and 5, a grounding bar.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The utility model provides a bi-polar ground circuit resistance and counterpoise resistance measuring device, includes measuring device 3 and sampling anchor clamps 2, and measuring device is used for exporting the constant current to measuring circuit, and measuring circuit includes by survey branch road 1, ground bar 5 and counterpoise 4 of series connection, as shown in figure 1, and sampling anchor clamps 2 adsorbs on ground bar, measures and measures ground bar voltage signal, and measuring device's input is connected to sampling anchor clamps 2's output.
The structure of the measuring device is shown in fig. 2, and the measuring device comprises a microcontroller, a constant current source, a current acquisition module, a voltage acquisition module and a human-computer interaction module, wherein the human-computer interaction module consists of a liquid crystal display and a key board. The output end of the microcontroller is connected with the input end of the constant current source, and two current output clamps of the constant current source are respectively clamped at one end of the tested branch and the middle part of the grounding bar; the output ends of the current acquisition module and the voltage acquisition module are respectively connected with the input end of the microcontroller, and the microcontroller calculates the resistance of the measured branch according to the output constant current, the acquired voltage at the two ends of the measured branch and the actual current value in the measurement loop; the man-machine interaction module is communicated with the microcontroller, the key board inputs a control instruction to the microcontroller, and the liquid crystal screen is used for displaying a measurement result.
The structure of the sampling clamp is shown in fig. 5, and comprises a casing 21, a magnet 22 which is convenient to be adsorbed on the grounding bar is fixedly arranged on the bottom end face of the casing, a telescopic probe 23 is respectively arranged on the bottom end faces of the casings positioned at two sides of the magnet, a circuit board is arranged in the casing, the input end of the circuit board is connected with the telescopic probe and used for signal conversion, and the output end of the circuit board is connected with a voltage signal wire 24, one end of the voltage signal wire is fixed on the.
The method is realized based on the measuring device, wherein the grounding bar is used as a sampling resistor, the length and the voltage of the grounding bar at two sides of a current injection point are respectively measured, and the current flowing to two ends can be obtained, the principle is shown in figure 3, in the figure, Rx is the resistance of a branch to be measured, Rg is the resistance of the grounding bar of the branch to be measured, Rw is the resistance of the grounding bar of the branch to be measured, and Ux is the voltage of the branch to be measured.
The on-site grounding bar is generally made of iron or copper materials, the resistivity and the cross-sectional area are constant, the middle part of the grounding bar is selected to apply current, and as shown in figure 4, the length L of an upper part and a lower part of an application point are respectively taken1、L2Two sections are respectively measured to obtain the voltage u1And u2Assuming that its resistance value is R1And R2Then, the first step is executed,
it is known that I ═ I1+I2，
u1＝I1*R1＝I1*ρL1/S，
u2＝I2*R2＝I2*ρL2S，
Then it is determined that,
namely, it is
Substituting the formula into I ═ I1+I2So as to obtain the compound with the characteristics of simple process,
wherein L is1、L2、u1And u2Measured separately.
I1The current value of the section of the grounding bar connected to the measured branch is the current value, namely, the current value flowing through the measured branch in the measurement loop can be obtained, and then the resistance of the measured branch can be calculated according to the measured voltage Ux of the measured branch.
The method for measuring the resistance of the branch to be measured by adopting the two sampling clamps specifically comprises the following steps.
A. The measured branch 1, two grounding bars 5 and the ground screen 4 are connected in series to form a measuring loop, as shown in fig. 1.
B. The two current output clamps of the measuring host are respectively clamped at one end of a measured branch and the middle part of a grounding bar connected with the other end of the measured branch, and two sampling clamps are respectively adsorbed at the upper part and the lower part of the grounding bar, namely one current output clamp of the measuring host is positioned on the grounding bar between the two sampling clamps; and connecting the voltage signal line to the measuring device.
When two sampling clamps are used for measurement, calibration coefficients of the two sampling clamps need to be calculated due to certain difference between the two sampling clamps. The specific method comprises the following steps: the sampling jig is placed on one side of the ground bar current injection point, and as shown in fig. 6, the calibration coefficient k of the two sampling jigs is calculated.
Wherein L is10、L20Respectively two sampling clamps of length u10And u20The collected voltages for the two sampling clamps.
C. The measuring device outputs constant current to the measuring loop, and collects the current value of the measured branch, the voltage values at two ends of the measured branch, the voltage value from the current injection point on the grounding bar to the endpoint of the measured branch and the voltage value from the current injection point on the grounding bar to the endpoint of the grounding grid.
D. C, calculating the current i actually flowing into the branch to be measured according to the data collected in the step Cx：
The measured branch resistance Rx is calculated by the following formula:
when the invention adopts a sampling clamp to measure the resistance of the branch to be measured, the clamp calibration condition does not exist, the voltage values (equivalent to the calibration coefficient k of 1) on the upper and lower grounding bars of the current injection point are directly obtained by twice measurement, and then the current of the branch to be measured and the resistance of the branch to be measured are obtained by calculation.
The core of the invention lies in that the shunt resistance is measured by using the grounding bar, including but not limited to the two measurement methods; the method of obtaining the shunt ratio by measuring the voltage of the ground bar in voltage ratio by using one or more sampling clamps or any other voltage measuring device in a single or multiple times belongs to the scope of the method.
Claims (6)
1. The utility model provides a bi-polar ground return circuit resistance and counterpoise resistance measuring device which characterized in that: the device comprises a measuring device for outputting constant current to a measuring circuit, wherein the measuring circuit comprises a measured branch (1), a grounding bar (5) and a ground grid (4) which are connected in series, the grounding bar is provided with a sampling clamp (2) for measuring a voltage signal of the grounding bar, and the output end of the sampling clamp (2) is connected with the input end of the measuring device.
2. The double-ended ground loop resistance and counterpoise resistance measurement device of claim 1, wherein: the measuring device comprises a microcontroller, a constant current source, a current acquisition module and a voltage acquisition module; the output end of the microcontroller is connected with the input end of the constant current source, and two current output clamps of the constant current source are respectively clamped at one end of the tested branch and the middle part of the grounding bar; the output ends of the current acquisition module and the voltage acquisition module are respectively connected with the input end of the microcontroller, and the microcontroller calculates the resistance of the measured branch according to the output constant current, the acquired voltage at the two ends of the measured branch and the actual current value in the measurement loop.
3. The double-ended ground loop resistance and counterpoise resistance measurement device of claim 2, wherein: the measuring device also comprises a man-machine interaction module consisting of a liquid crystal screen and a key board, and the man-machine interaction module is communicated with the microcontroller.
4. The double-ended ground loop resistance and counterpoise resistance measurement device of claim 1, wherein: the sampling fixture comprises a shell (21), a magnet (22) convenient to adsorb on a grounding bar is fixedly arranged on the bottom end face of the shell, a telescopic probe (23) is respectively arranged on the bottom end faces of the shells positioned on two sides of the magnet, a circuit board used for signal conversion and connected with the telescopic probe and an input end is arranged in the shell, and a voltage signal line (24) fixed on the shell is connected with one end of the output end of the circuit board.
5. A method for measuring the resistance of a double-end grounding loop and the resistance of a grounding grid is realized based on the measuring device of any one of claims 1 to 4, and comprises the following steps:
A. the measured branch (1), the grounding bar (5) and the ground screen (4) are connected in series to form a measuring loop;
B. respectively clamping two current output clamps of a measuring host at one end of a measured branch and the middle part of a grounding bar, adsorbing a sampling clamp on the grounding bar, and connecting a voltage signal wire to a measuring device;
C. the measuring device outputs constant current to the measuring loop, and collects the current value of the measured branch, the voltage values at two ends of the measured branch, the voltage value from the current injection point on the grounding bar to the endpoint of the measured branch and the voltage value from the current injection point on the grounding bar to the endpoint of the grounding grid;
D. and C, calculating the resistance of the branch to be tested according to the data collected in the step C.
6. The method as claimed in claim 5, wherein in step B, two sampling jigs are used to collect voltages of the upper and lower parts of the ground bar respectively or one voltage sampling jig is used to measure voltages of the upper and lower parts of the ground bar respectively so as to calculate the shunt ratio.
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| CN202110080374.9A CN112904087A (en) | 2021-01-21 | 2021-01-21 | Device and method for measuring resistance of double-end grounding loop and resistance of grounding grid |
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| CN202110080374.9A CN112904087A (en) | 2021-01-21 | 2021-01-21 | Device and method for measuring resistance of double-end grounding loop and resistance of grounding grid |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113917235A (en) * | 2021-10-19 | 2022-01-11 | 广东电网有限责任公司广州供电局 | Resistance comprehensive measurement system based on intelligent current-voltage clamp meter |
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2021
- 2021-01-21 CN CN202110080374.9A patent/CN112904087A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113917235A (en) * | 2021-10-19 | 2022-01-11 | 广东电网有限责任公司广州供电局 | Resistance comprehensive measurement system based on intelligent current-voltage clamp meter |
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