CN213398688U - Multifunctional tester and testing system - Google Patents
Multifunctional tester and testing system Download PDFInfo
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- CN213398688U CN213398688U CN202021262953.2U CN202021262953U CN213398688U CN 213398688 U CN213398688 U CN 213398688U CN 202021262953 U CN202021262953 U CN 202021262953U CN 213398688 U CN213398688 U CN 213398688U
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Abstract
The utility model provides a multi-functional tester and test system belongs to the electrical measurement field. The multifunctional tester comprises an excitation source, an operation processing module and a connecting module, wherein the connecting module comprises a plurality of wiring ports, the output end of the excitation source is connected with the wiring ports of the connecting module, the control end of the excitation source is connected with the operation processing module, and the operation processing module comprises a pre-amplification unit, a current-voltage conversion unit, a program-controlled amplification unit, an analog-digital conversion unit and a processing unit; the processing unit comprises an excitation source control subunit and a grounding parameter calculation subunit, the excitation source control subunit is connected with the control end of the excitation source, the grounding parameter calculation subunit is connected with the excitation source control subunit, and the output end of the analog-to-digital conversion unit is connected with the grounding parameter calculation subunit. The multifunctional tester can be used for measuring grounding parameters such as grounding resistance, soil resistivity, on-resistance, power frequency ground voltage, power frequency current and the like, and other testers are not needed.
Description
Technical Field
The disclosure relates to the technical field of electrical measurement, in particular to a multifunctional tester and a testing system.
Background
High voltage power systems such as substations and power stations often require certain electrical equipment to be connected to ground for personnel safety and normal operation. Since the earth contains an electrolyte such as moisture, it can conduct electricity. When the ground level of the power equipment is inserted into the ground, the ground field is formed by taking the ground point as the center of sphere. The current flowing into the ground electrode flows into the ground through the ground field. When the grounding device is in poor grounding and is struck by lightning, instantaneous large current can be generated, so that high voltage is formed on the grounding device, the formed high voltage can damage equipment and even cause electric shock to personnel, and therefore the grounding condition needs to be detected regularly.
At present, the grounding condition of the power equipment is usually determined by detecting grounding parameters such as grounding resistance, conducting resistance and the like, and a special test instrument can be adopted for line connection detection when the grounding parameters are detected.
SUMMERY OF THE UTILITY MODEL
The embodiment of the disclosure provides a multifunctional tester and a testing system, which can measure grounding parameters such as grounding resistance, soil resistivity, on-resistance, power frequency ground voltage, power frequency current and the like through one instrument without adopting other testers. The technical scheme is as follows:
in a first aspect, a multifunctional tester is provided, which includes an excitation source, an operation processing module and a connection module, where the connection module includes a plurality of wiring ports, an output end of the excitation source is connected with the wiring ports of the connection module, a control end of the excitation source is connected with the operation processing module, and the operation processing module includes a pre-amplification unit, a current-voltage conversion unit, a program-controlled amplification unit, an analog-to-digital conversion unit and a processing unit;
the input end of the pre-amplification unit and the input end of the current-voltage conversion unit are respectively connected with the two wiring ports of the connection module, the output end of the pre-amplification unit and the output end of the current-voltage conversion unit are both connected with the input end of the program-controlled amplification unit, the output end of the program-controlled amplification unit is connected with the input end of the analog-to-digital conversion unit, and the output end of the analog-to-digital conversion unit is connected with the processing unit;
the processing unit comprises an excitation source control subunit and a grounding parameter calculating subunit, the excitation source control subunit is connected with the control end of the excitation source, the grounding parameter calculating subunit is connected with the excitation source control subunit, and the output end of the analog-to-digital conversion unit is connected with the grounding parameter calculating subunit.
Optionally, the excitation source comprises a programmed dc current source, a programmed ac current source, and a programmed ac voltage source;
the plurality of wiring ports at least comprise a C wiring port and a CT1 wiring port, the C wiring port can be selectively connected with one of the programmable direct current source and the programmable alternating current source, and the CT1 wiring port is connected with the programmable alternating current voltage source.
Optionally, the plurality of connection ports further includes a P connection port, a CT2 connection port, an Ec connection port, and an Ep connection port, the P connection port is connected to the pre-amplification unit, the CT2 connection port is connected to the current-voltage conversion unit, and the Ec connection port and the Ep connection port are grounded.
Optionally, the multifunctional tester further comprises a test wire, wherein the test wire comprises a plurality of first test wires and a plurality of second test wires;
the C wiring port, the P wiring port, the Ec wiring port and the Ep wiring port are respectively connected with one end of one first test lead, and the other end of each first test lead is provided with a probe clamp;
the CT1 wiring port and the CT2 wiring port are respectively connected with one end of one second test lead, and the other end of each second test lead is provided with a clamp.
Optionally, the operation processing module further includes a filter unit, an input end of the filter unit is selectively connectable to one of the pre-amplification unit and the current-voltage conversion unit, and an output end of the filter unit is connected to an input end of the program-controlled amplification unit.
Optionally, the multifunctional tester further includes a first mode selection switch and a second mode selection switch, a control end of the first mode selection switch and a control end of the second mode selection switch are both connected to the excitation source control subunit, and the first mode selection switch and the second mode selection switch are both single-pole double-throw switches having three contacts;
a first contact of the first mode selection switch is connected with the output end of the program-controlled direct current source, a second contact of the first mode selection switch is connected with the output end of the program-controlled alternating current source, and a third contact of the first mode selection switch is connected with the C wiring port;
a first contact of the second mode selection switch is connected with the output end of the pre-amplification unit, a second contact of the second mode selection switch is connected with the output end of the current-voltage conversion unit, and a third contact of the second mode selection switch is connected with the input end of the filter unit.
Optionally, the multifunctional tester comprises a housing, a display panel and a function key embedded on the housing;
the processing unit also comprises a grounding parameter storage subunit, the grounding parameter storage subunit is connected with the grounding parameter calculation subunit, the display panel is connected with the grounding parameter storage subunit and the grounding parameter calculation subunit, and the function key is connected with the grounding parameter storage subunit and the grounding parameter calculation subunit;
the excitation source and the operation processing module are both positioned in the shell, and the plurality of wiring ports in the connecting module are all arranged on the surface of the shell.
Optionally, the multifunctional tester further includes a mode selection knob disposed on the surface of the housing, the mode selection knob is connected to the excitation source control subunit and the ground parameter calculation subunit, the mode selection knob has a plurality of gears, and the plurality of gears include at least one of an on-resistance measurement mode gear, a three-pole ground resistance measurement mode gear, a single-clamp ground resistance measurement mode gear, a double-clamp ground resistance measurement mode gear, a soil resistivity measurement mode gear, a power frequency ground voltage mode gear, and a power frequency current mode gear.
Optionally, the multifunctional tester further comprises a test key arranged ON the surface of the shell, the test key is connected with the excitation source control subunit and the grounding parameter calculation subunit, and the test key has two stages of "ON" and "OFF".
In a second aspect, there is provided a multifunctional test system comprising a multifunctional test meter and a probe as described in the first aspect.
The technical scheme provided by the embodiment of the disclosure has the following beneficial effects:
by arranging the multifunctional tester, an excitation source in the multifunctional tester can generate an excitation signal to be output from the wiring port when the multifunctional tester is used specifically. And the excitation source control subunit in the operation processing module can control the excitation source to generate an excitation signal required by measurement. Meanwhile, a preamplification unit and a current-voltage conversion unit in the operation processing module can acquire voltage or current required by calculation of each grounding parameter through a wiring port, the acquired voltage or current signals are amplified or subjected to current-voltage conversion, and the processed voltage signals are amplified and subjected to analog-to-digital conversion again through a program control amplification unit and an analog-to-digital conversion unit to obtain digital signals required by the processing unit. And then the grounding parameter calculating subunit in the processing module can calculate grounding parameters such as grounding resistance, soil resistivity, on-resistance, power frequency ground voltage, power frequency current and the like according to the digital signal, so that the function is comprehensive. The grounding parameters such as grounding resistance, soil resistivity, on-resistance, power frequency ground voltage, power frequency current and the like are measured by one instrument, and other test instruments are not needed, so that the practicability of the tester is greatly improved, and different test requirements of testers can be met.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a system diagram of a multi-function test meter provided by an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of an external structure of a multifunctional tester provided in the embodiments of the present disclosure;
fig. 3 is a measurement schematic diagram of a multifunctional tester provided by the embodiment of the present disclosure, which measures a ground resistance by a three-pole method;
FIG. 4 is a schematic diagram of a measurement method for measuring ground resistance by a single clamp method in a multifunctional tester according to an embodiment of the present disclosure;
fig. 5 is a schematic diagram illustrating a measurement principle of a multifunctional tester according to an embodiment of the present disclosure, in which a double-clamp method is used to measure a ground resistance;
FIG. 6 is a schematic diagram of a multifunctional tester for measuring soil resistivity according to an embodiment of the disclosure;
FIG. 7 is a schematic diagram of a multifunctional tester for measuring on-resistance according to an embodiment of the disclosure;
fig. 8 is a measurement schematic diagram of a multifunctional tester provided by the embodiment of the disclosure for measuring power frequency ground voltage;
fig. 9 is a schematic diagram illustrating a measurement principle of a multifunctional tester for measuring a power frequency current according to an embodiment of the disclosure.
Detailed Description
To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Because various testers on the current market are generally single in function, one tester can only measure one parameter. In an actual test environment, various unexpected situations occur, and a voltage or a grounding current for measuring the working frequency is sometimes needed. At this time, additional voltmeters and ampere meters are needed to assist in testing, and manpower and material resources are consumed. When the grounding resistance, the soil resistivity, the on-resistance, the power frequency ground voltage and the power frequency current need to be measured, after one parameter is measured each time, the connecting line of the measuring instrument needs to be detached, then other measuring instruments need to be replaced, and the connecting line is connected to the next measuring point to continue to measure, so that the detection efficiency is low.
Fig. 1 is a system schematic diagram of a multifunctional tester provided by an embodiment of the present disclosure, and as shown in fig. 1, the multifunctional tester includes an excitation source 10, an arithmetic processing module 20, and a connection module 30. The connection module 30 includes a plurality of connection ports, the output terminal of the excitation source 10 is connected to the connection port of the connection module 30, and the control terminal of the excitation source 10 is connected to the operation processing module 20. The operation processing module 20 includes a pre-amplification unit 21, a current-voltage conversion unit 22, a program-controlled amplification unit 23, an analog-to-digital conversion unit 24, and a processing unit 25.
The input end of the pre-amplification unit 21 and the input end of the current-voltage conversion unit 22 are respectively connected to two wiring ports of the connection module 30, and the output end of the pre-amplification unit 21 and the output end of the current-voltage conversion unit 22 are both connected to the input end of the program-controlled amplification unit 23. The output end of the program-controlled amplifying unit 23 is connected with the input end of the analog-to-digital conversion unit 24, and the output end of the analog-to-digital conversion unit 24 is connected with the processing unit 25.
The processing unit 25 includes an excitation source control subunit 251 and a ground parameter calculation subunit 252. The excitation source control subunit 251 is connected to the control terminal of the excitation source 10. The grounding parameter calculation subunit 252 is connected to the excitation source control subunit 251, and the output end of the analog-to-digital conversion unit 24 is connected to the grounding parameter calculation subunit 252.
The embodiment of the disclosure provides a multifunctional tester, and when the multifunctional tester is used specifically, an excitation source in the multifunctional tester can generate an excitation signal to be output from a wiring port. And the excitation source control subunit in the operation processing module can control the excitation source to generate an excitation signal required by measurement. Meanwhile, a preamplification unit and a current-voltage conversion unit in the operation processing module can acquire voltage or current required by calculation of each grounding parameter through a wiring port, the acquired voltage or current signals are amplified or subjected to current-voltage conversion, and the processed voltage signals are amplified and subjected to analog-to-digital conversion again through a program control amplification unit and an analog-to-digital conversion unit to obtain digital signals required by the processing unit. And then the grounding parameter calculating subunit in the processing module can calculate grounding parameters such as grounding resistance, soil resistivity, on-resistance, power frequency ground voltage, power frequency current and the like according to the digital signal, so that the function is comprehensive. The grounding parameters such as grounding resistance, soil resistivity, on-resistance, power frequency ground voltage, power frequency current and the like are measured by one instrument, and other test instruments are not needed, so that the practicability of the tester is greatly improved, and different test requirements of testers can be met.
Optionally, the arithmetic processing module 20 further includes a filter unit 26. An input of the filter unit 26 is selectively connectable to one of the pre-amplification unit 21 and the current-voltage conversion unit 22, and an output of the filter unit 26 is connected to an input of the programmable amplification unit 23.
The filter unit 26 is illustratively a filter, and the filter can be configured to filter the interference signal, so as to ensure the accuracy of the measured parameter.
Optionally, the excitation source 10 comprises a programmed dc current source 11, a programmed ac current source 12 and a programmed ac voltage source 13. The excitation source 10 may generate a dc current signal, an ac current signal and an ac voltage signal required for the measurement.
The plurality of wiring ports at least comprise a C wiring port and a CT1 wiring port, the C wiring port can be selectively connected with one of the programmable direct current source 11 and the programmable alternating current source 12, and the CT1 wiring port is connected with the programmable alternating current voltage source 13.
The excitation source control subunit 251 may control the programmable dc current source 11 to output a set amount of dc current from the C-connection port, control the programmable ac current source 12 to output a set amount of ac current from the C-connection port, or control the programmable ac voltage 13 to output a set amount of ac voltage from the CT1 connection port.
Illustratively, the programmable dc current source 11 may output dc currents of 10mA, 50mA and 200 mA. The programmable ac current source 12 can output ac currents of 1mA, 5mA and 10 mA. The programmable ac voltage source 13 can output an ac voltage of 20V.
In this embodiment, the programmable dc current source 11, the programmable ac current source 12, and the programmable ac voltage source 13 are all composed of an operational amplifier and a triode, and the driving source control subunit 251 can control each driving source to output a current or a voltage of a set magnitude by controlling the amplification factor of the operational amplifier in each driving source.
Optionally, the multifunctional tester further comprises a first mode selection switch S1 and a second mode selection switch S2, and a control terminal of the first mode selection switch S1 and a control terminal of the second mode selection switch S2 are both connected to the excitation source control subunit 251. The first mode selection switch S1 and the second mode selection switch S2 are each a single pole double throw switch having three contacts.
A first contact of the first mode selection switch S1 is connected to the output of the programmable dc current source 11, a second contact of the first mode selection switch S1 is connected to the output of the programmable ac current source 12, and a third contact of the first mode selection switch S1 is connected to the C terminal port.
A first contact of the second mode selection switch S2 is connected to the output terminal of the pre-amplifying unit 21, a second contact of the second mode selection switch S2 is connected to the output terminal of the current-voltage converting unit 22, and a third contact of the second mode selection switch S2 is connected to the input terminal of the filter unit 26.
In a specific use, the excitation source control subunit 251 may also control connection between respective contacts of the first mode selection switch S1 and the second mode selection switch S2 to output dc current, ac current, or ac voltage required for measurement, respectively.
When the first contact of the first mode selection switch S1 and the third contact are controlled to be connected, the excitation source 10 outputs a dc current to the C terminal port. When the second contact of the first mode selection switch S1 and the third contact are controlled to be connected, the excitation source 10 outputs an alternating current to the C terminal port.
When the first contact and the third contact of the second mode selection switch S2 are controlled to be connected, a signal detected by the P connection port is output to the filter unit 26 through the pre-amplifying unit 21. When the second contact of the second mode selection switch S2 and the third contact are controlled to be connected, the current signal detected by the CT2 connection port is converted into a voltage signal by the current-voltage conversion unit 22 and then output to the filter unit 26.
Optionally, the plurality of connection ports further includes a P connection port connected to the pre-amplification unit 21, a CT2 connection port, an Ec connection port and an Ep connection port, the CT2 connection port is connected to the current-voltage conversion unit 22, and the Ec connection port and the Ep connection port are grounded.
The measuring personnel can realize the measurement of the ground resistance by adopting a single-clamp method, a double-clamp method and a three-level method by arranging the wiring port and connecting the wiring port to different measuring positions by adopting a lead, so that different measuring methods can be selected according to different measuring environments to measure the ground resistance.
Illustratively, the pre-amplification unit 21 amplifies the signal collected by the P wiring port and sends the signal to the program-controlled amplification unit 23, the current-voltage conversion unit 22 converts the current signal collected by the CT2 wiring port into a voltage signal and sends the voltage signal to the program-controlled amplification unit 23, the program-controlled amplification unit 23 amplifies the voltage of the received signal to a voltage required by the input of the analog-to-digital conversion module 24 and sends the voltage to the analog-to-digital conversion module 24, and the analog-to-digital conversion module 24 converts the received analog signal into a digital signal and sends the digital signal to the processing unit 25.
Fig. 2 is a schematic external structural diagram of a multifunctional tester provided in an embodiment of the present disclosure, and as shown in fig. 2, the multifunctional tester further includes a test wire 40, and the test wire 40 includes a plurality of first test wires 41 and a plurality of second test wires 42.
The C wiring port, the P wiring port, the Ec wiring port and the Ep wiring port are connected to one end of one first test wire 41, respectively, and the other end of each first test wire 41 is provided with a probe clip 41a so as to be connected to a probe.
The CT1 connection port and the CT2 connection port are respectively connected to one end of a second test wire 42, and the other end of each second test wire 42 is provided with a clamp 42a so as to be clamped on the grounding wire.
Optionally, the multifunctional tester includes a housing 50, a display panel 51 and function keys 54 embedded on the housing 50.
The processing unit 25 further includes a ground parameter storage subunit 253. The grounding parameter storage subunit 253 is connected with the grounding parameter calculation subunit 252, the grounding parameter storage subunit 253 of the display panel 51 is connected with the grounding parameter calculation subunit 252, and the function key 54 is connected with the grounding parameter storage subunit 253 and the grounding parameter calculation subunit 252.
The excitation source 10 and the arithmetic processing module 20 are both located in the housing 50, and a plurality of wiring ports in the connection module 30 are all provided on the surface of the housing 50.
The housing 50 may be protective and the display panel 51 may be used to display the calculated various grounding parameters. By using the function key 54, it is possible to instruct the grounding parameter calculation subunit 252 to store each grounding parameter into the grounding parameter storage subunit 253, and read each grounding parameter stored in the parameter storage subunit 253 to be displayed on the display panel 51.
Illustratively, the Display panel 51 is an LCD (Liquid Crystal Display) panel.
Optionally, the multifunctional tester further comprises a mode selection knob 52 disposed on the surface of the housing 50, the mode selection knob 52 being connected to the excitation source control subunit 251 and the ground parameter calculation subunit 252, the mode selection knob 52 having a plurality of gear positions.
The plurality of gears include at least one of an on-resistance measurement mode gear M1, a three-pole method ground resistance measurement mode gear M2, a single-clamp ground resistance measurement mode gear M3, a double-clamp ground resistance measurement mode gear M4, a soil resistivity measurement mode gear M5, a power frequency ground voltage mode gear M6, and a power frequency current mode gear M7.
In specific use, different grounding parameters can be measured by rotating the mode selection knob 52 to select different gears. The on-resistance can be measured in the on-resistance measurement mode gear M1, and the ground resistance can be measured in the three-pole method ground resistance measurement mode gear M2, the single-clamp ground resistance measurement mode gear M3 and the double-clamp ground resistance measurement mode gear M4.
The method can measure the soil resistivity in the soil resistivity measurement mode gear M5, the power frequency ground voltage in the power frequency ground voltage mode gear M6 and the power frequency current in the power frequency current mode gear M7.
When the mode selection knob 52 is rotated to a certain shift position, the excitation source control subunit 251 controls the excitation source 10 to output a current or voltage of a set magnitude required in the shift position mode based on a trigger signal generated by the shift position. And the excitation source control subunit 251 may also control the connection between the respective contacts of the first mode selection switch S1 based on the trigger signal generated by the shift position so that the excitation source 10 outputs the dc current, the ac current, or the ac voltage required in the shift position mode, while controlling the connection between the respective contacts of the second mode selection switch S2 so that the pre-amplification unit 21 or the current-voltage conversion unit 22 is connected to the filter unit 26. Then, the ground parameter calculating subunit 252 may calculate the magnitude of the ground parameter in the shift mode according to the magnitude of the current or voltage output by the excitation source 10 and the signal detected by each connection port.
For example, when the mode selection knob 52 is rotated to the on-resistance measurement mode shift position M1, the excitation source control subunit 251 controls the connection of the first contact and the third contact of the first mode selection switch S1 based on the trigger signal generated by the shift position, so that the excitation source 10 is the program-controlled dc current source 11, outputting a dc current. Meanwhile, the excitation source control subunit 251 controls the first contact and the third contact of the second mode selection switch S2 to be connected based on the trigger signal generated by the shift position, so that the pre-amplification unit 21 is connected to the filter unit 26. The detailed procedure can be seen in the following description relating to the specific measurement procedure.
Optionally, the multifunctional tester further comprises a test button 53 disposed on the surface of the housing 50. The test key 53 is connected to the excitation source control subunit 251 and the ground parameter calculation subunit 252, and the test key 53 has two stages of "ON" and "OFF".
The test is started when the test button 53 is in the "ON" position. When the test button 53 is in the OFF position, the test is stopped.
For example, the following brief description explains a specific measurement process when the multifunctional tester provided by the embodiment of the present disclosure is used to measure each grounding parameter:
first, measure the earth resistance
The grounding resistance is applied between the shell of the tested device and the safety grounding end thereof by outputting alternating current or direct current, the voltage drop generated when the current flows through the tested device is measured, and then the grounding conduction resistance value is calculated according to the voltage-current ratio.
Among them, the test method of the ground resistance generally includes a three-pole method, a single clamp method, a double clamp method, and the like. The tripolar method has accurate test results, but needs to be provided with auxiliary probes. The single clamp method is an extension of the three-pole method, and in a ground grid system with a plurality of grounding electrodes at the same time, the grounding state of each grounding stage can be qualitatively analyzed by the single clamp method. The double-clamp method can measure the grounding resistance without disconnecting the grounding electrode, is also suitable for the occasion of multipoint grounding, and has the defect of low precision.
Fig. 3 is a schematic diagram illustrating a measurement principle of a three-pole method for measuring a ground resistance of the multifunctional ground resistance tester according to the embodiment of the present disclosure, as shown in fig. 3, at this time, the mode selection knob 52 is rotated to a three-pole method ground resistance measurement mode gear position M2, and the multifunctional ground resistance tester is in a three-pole method ground resistance measurement mode. The first mode selection switch S1 is controlled by the excitation source control subunit 251 to switch the excitation source 10 to the programmed ac current source 12. And the excitation source control subunit 251 controls the program-controlled alternating current source 12 to output alternating currents with different magnitudes, so as to achieve the purpose of outputting different test current signals, thereby improving the test precision. The current signal outputs a current through the C connection port and the Ec connection port. The pre-amplifying unit 21 is connected to the filter unit 26 by controlling the second mode selection switch S2 through the excitation source control subunit 251. The voltages obtained by the P wiring port and the Ep wiring port can be measured through the pre-amplification unit 21, the filter unit 26, the program control amplification unit 23 and the analog-to-digital conversion unit 24. Finally, the grounding resistance can be calculated by the grounding parameter calculating subunit 252, that is, the obtained voltage value is divided by the current value output by the program-controlled ac current source.
Fig. 4 is a schematic diagram illustrating a measurement principle of a multifunctional tester according to an embodiment of the present disclosure, in which a single-clamp method is used to measure a ground resistance, and as shown in fig. 4, the mode selection knob 52 is rotated to a single-clamp ground resistance measurement mode shift position M3, so that the multifunctional tester is in a single-clamp ground resistance measurement mode. The first mode selection switch S1 is controlled by the excitation source control subunit 251 to switch the excitation source 10 to the programmed ac current source 12. And the excitation source control subunit 251 controls the program-controlled alternating current source 12 to output alternating currents with different magnitudes, so as to achieve the purpose of outputting different test current signals, thereby improving the test precision. The current signal outputs a current through the C connection port and the Ec connection port. A voltage drop is generated across the ground electrode being measured. The excitation source control subunit 251 controls the second mode selection switch S2 to connect the pre-amplification unit 21 with the filter unit 26, and the voltage drop across the P connection port and the Ep connection port measured by the pre-amplification unit 21, the filter unit 26, the program control amplification unit 23, and the analog-to-digital conversion unit 24 can be measured. The second mode selection switch S2 is then controlled by the excitation source control subunit 251 to connect the current-voltage conversion unit 22 with the filter unit 26. The current flowing through the branch to be tested induces an induced current in the CT2 connection port, and the induced current is converted into a voltage signal by the current-voltage conversion unit 22. The power frequency interference signal is filtered by the filter unit 26, the voltage signal is amplified by the program control amplifying unit 23, the analog-to-digital conversion unit 24 converts the analog signal into a digital signal, and finally the grounding parameter calculating subunit 252 divides the measured voltage between the P wiring port and the Ep wiring port by the measured branch current to calculate the branch grounding resistance.
Fig. 5 is a schematic diagram illustrating a measurement principle of a multifunctional tester using a double-clamp method to measure ground resistance according to an embodiment of the present disclosure, and as shown in fig. 5, the mode selection knob 52 is rotated to a double-clamp ground resistance measurement mode shift position M4, and the multifunctional tester is in a double-clamp ground resistance measurement mode. The first mode selection switch S1 is controlled by the excitation source control subunit 251 to switch the excitation source 10 to the programmed ac voltage source 13. The programmed ac voltage source 13 may output a sine wave signal to the CT1 wiring port. The pliers at the other end of the second test wire 42 connected to the CT1 clamp the down lead of the tested grounding body, the jaws of the pliers will generate an excitation voltage in the test loop, and the excitation voltage is the voltage signal output by the excitation source divided by the turn ratio of the jaws (i.e. the turn ratio of the primary coil to the secondary coil). And the excitation current is generated by a jaw test circuit externally connected with a CT2 wiring port. The excitation source control subunit 251 controls the second mode selection switch S2, so that the current-voltage conversion unit 22 is connected to the filter unit 26, the excitation current is converted into a voltage signal by the current-voltage conversion unit 22, the voltage signal is output to the grounding parameter calculation subunit 252 through the filter unit 26, the program control amplification unit 23 and the analog-to-digital conversion unit 24, and finally the grounding resistance is calculated by dividing the excitation voltage by the excitation current by the grounding parameter calculation subunit 252.
Secondly, measuring the resistivity of the soil
Fig. 6 is a schematic diagram illustrating a measurement principle of the multifunctional ground resistance tester according to the embodiment of the present disclosure, as shown in fig. 6, when the mode selection knob 52 is rotated to the soil resistivity measurement mode shift position M5, the multifunctional ground resistance tester is in the soil resistivity measurement mode. And arranging auxiliary probes M at equal intervals a on a straight line, and sequentially connecting the auxiliary probes M with the Ec, Ep, P and C wiring ports through test wires. The first mode selection switch S1 is controlled by the excitation source control subunit 251 to switch the excitation source 10 to output the program-controlled ac current source 12, and the current is output through the C connection port and the Ec connection port. The pre-amplifying unit 21 is connected to the filter unit 26 by controlling the second mode selection switch S2 through the excitation source control subunit 251. The voltages obtained by the P wiring port and the Ep wiring port are measured by the pre-amplification unit 21, the filter unit 26, the program control amplification unit 23 and the analog-to-digital conversion unit 24, and the apparent resistance is calculated by the grounding parameter calculation subunit 252, that is, the obtained voltage value is divided by the current value output by the program control alternating current power supply. And then, according to the apparent resistance R and the distance a obtained by measurement and calculation, the soil resistivity can be calculated by the following formula.
ρ＝2πaR
Where ρ represents the resistivity of the soil, a represents the spacing between two adjacent probes, and R represents the apparent resistance.
It should be noted that the apparent resistance here means the visible resistance displayed on the display panel of the multifunctional tester, and is an intermediate parameter and has no practical meaning.
Thirdly, measuring the on-resistance
The on-resistance refers to the on-resistance between the grounding belt and the safety grounding terminal on the same floor or at intervals of the building. When a fault current occurs inside the electrical equipment, there is a risk of electric shock if the electrical equipment is not properly connected to the earth grid.
Fig. 7 is a schematic diagram of the multifunctional ground resistance tester provided in the embodiment of the present disclosure for measuring on-resistance, as shown in fig. 7, when the mode selection knob 52 is rotated to the on-resistance measurement mode shift position M1, the multifunctional ground resistance tester is in the on-resistance measurement mode. The C wiring port and the Ec wiring port are connected to two ends of the tested grounding band and the grounding terminal, the excitation source control subunit 251 controls the first mode selection switch S1 to switch the excitation source 10 to the program-controlled direct current source 11, and the program-controlled direct current source 11 has a current-limiting protection function. The current is output from the C wiring port and the Ec wiring port. A voltage drop occurs when current flows through the resistor under test. The pre-amplifying unit 21 is connected to the filter unit 26 by controlling the second mode selection switch S2 through the excitation source control subunit 251. The voltage signals acquired through the P wiring port and the Ep wiring port are input into the preamplification unit 21 and the filter unit 26, the filter unit 26 filters power frequency interference, the program control amplification unit 23 amplifies the voltage signals to a proper range and sends the amplified voltage signals to the analog-to-digital conversion unit 24, and finally the grounding parameter calculation subunit 252 calculates the on-resistance, namely, the acquired voltage value is divided by the current value output by the program control alternating current source.
Fourthly, measuring power frequency ground voltage
The power frequency ground voltage is the potential difference between the shell, the ground wire and the like of the grounding device and a zero potential point when the electrical device has a ground fault.
Fig. 8 is a schematic diagram of the multifunctional ground resistance tester provided by the embodiment of the present disclosure for measuring power frequency ground voltage, and as shown in fig. 8, at this time, the mode selection knob 52 is rotated to the power frequency ground voltage mode shift position M6, and the multifunctional ground resistance tester is in the power frequency ground voltage mode. An auxiliary probe is used, and an Ep wiring port is connected with the auxiliary probe through a lead, and a P wiring port is connected with the tested grounding body through a lead. The pre-amplifying unit 21 is connected to the filter unit 26 by controlling the second mode selection switch S2 through the excitation source control subunit 251. The voltage on the grounding electrode to be measured is measured by the preamplification unit 21, the filter unit 26, the program control amplification unit 23 and the analog-to-digital conversion unit 24, and then the grounding parameter calculation subunit 252 calculates and displays the power frequency ground voltage, namely, the measured voltage on the grounding electrode to be measured is multiplied by a coefficient k, so that the power frequency ground voltage can be obtained.
In the present embodiment, the coefficient k may be determined according to gain multiples of the preamplification unit 21, the filter unit 26, and the program-controlled amplification unit 23.
Illustratively, the coefficient k is 100.
Fifth, measuring the power frequency current
The power frequency current is the current flowing into the ground due to equipment failure and can be generally measured by a power frequency ammeter.
Fig. 9 is a schematic diagram illustrating a measurement principle of the multifunctional ground resistance tester according to the embodiment of the present disclosure, and as shown in fig. 9, at this time, the mode selection knob 52 is rotated to the power frequency current mode shift M7, and the multifunctional ground resistance tester is in the power frequency current mode. The CT2 connection port is externally connected with a second test lead, a tested ground wire is clamped into the jaw by using a clamp, the ground current generates an induced current in the CT2 connection port current, and the magnitude of the current is the ground current divided by the transformation ratio of the induced jaw. The second mode selection switch S2 is controlled by the excitation source control subunit 251 to connect the current-voltage conversion unit 22 with the filter unit 26. The exciting current is converted into a voltage signal by the current-voltage conversion unit 22, and the induced current can be measured by the filter unit 26, the program-controlled amplification unit 23 and the analog-digital conversion unit 24. The same applies to the measurement of the operating current.
The embodiment of the disclosure also provides a multifunctional test system, which comprises the multifunctional tester and the probe according to the embodiment.
The above description is intended to be exemplary only and not to limit the present disclosure, and any modification, equivalent replacement, or improvement made without departing from the spirit and scope of the present disclosure is to be considered as the same as the present disclosure.
Claims (10)
1. The multifunctional tester is characterized by comprising an excitation source (10), an operation processing module (20) and a connecting module (30), wherein the connecting module (30) comprises a plurality of wiring ports, the output end of the excitation source (10) is connected with the wiring ports of the connecting module (30), the control end of the excitation source (10) is connected with the operation processing module (20), and the operation processing module (20) comprises a pre-amplification unit (21), a current-voltage conversion unit (22), a program control amplification unit (23), an analog-to-digital conversion unit (24) and a processing unit (25);
the input end of the pre-amplification unit (21) and the input end of the current-voltage conversion unit (22) are respectively connected with the two wiring ports of the connection module (30), the output end of the pre-amplification unit (21) and the output end of the current-voltage conversion unit (22) are both connected with the input end of the program-controlled amplification unit (23), the output end of the program-controlled amplification unit (23) is connected with the input end of the analog-to-digital conversion unit (24), and the output end of the analog-to-digital conversion unit (24) is connected with the processing unit (25);
the processing unit (25) comprises an excitation source control subunit (251) and a grounding parameter calculating subunit (252), wherein the excitation source control subunit (251) is connected with the control end of the excitation source (10), the grounding parameter calculating subunit (252) is connected with the excitation source control subunit (251), and the output end of the analog-to-digital conversion unit (24) is connected with the grounding parameter calculating subunit (252).
2. The multifunctional test meter according to claim 1, characterized in that the excitation source (10) comprises a programmed direct current source (11), a programmed alternating current source (12) and a programmed alternating voltage source (13);
the plurality of wiring ports at least comprise a C wiring port and a CT1 wiring port, the C wiring port can be selectively connected with one of the programmable direct current source (11) and the programmable alternating current source (12), and the CT1 wiring port is connected with the programmable alternating current voltage source (13).
3. The multi-function tester as recited in claim 2, wherein the plurality of wiring ports further includes a P wiring port connected to the pre-amplification unit (21), a CT2 wiring port, an Ec wiring port, and an Ep wiring port, the CT2 wiring port being connected to the current-voltage conversion unit (22), the Ec wiring port and the Ep wiring port being grounded.
4. The multifunctional test meter according to claim 3, further comprising a test wire (40), said test wire (40) comprising a plurality of first test wires (41) and a plurality of second test wires (42);
the C wiring port, the P wiring port, the Ec wiring port and the Ep wiring port are respectively connected with one end of one first test lead (41), and the other end of each first test lead (41) is provided with a probe clip (41 a);
the CT1 wiring port and the CT2 wiring port are respectively connected with one end of one second test lead (42), and the other end of each second test lead (42) is provided with a clamp (42 a).
5. The multifunctional tester according to claim 2, characterized in that the arithmetic processing module (20) further comprises a filter unit (26), an input of the filter unit (26) being selectively connectable to one of the pre-amplification unit (21) and the current-voltage conversion unit (22), an output of the filter unit (26) being connected to an input of the programmable amplification unit (23).
6. The multi-function tester of claim 5, further comprising a first mode selection switch (S1) and a second mode selection switch (S2), a control terminal of the first mode selection switch (S1) and a control terminal of the second mode selection switch (S2) both being connected to the stimulus source control subunit (251), the first mode selection switch (S1) and the second mode selection switch (S2) both being single-pole double-throw switches having three contacts;
a first contact of the first mode selection switch (S1) is connected to an output of the programmable dc current source (11), a second contact of the first mode selection switch (S1) is connected to an output of the programmable ac current source (12), and a third contact of the first mode selection switch (S1) is connected to the C connection port;
a first contact of the second mode selection switch (S2) is connected to the output of the pre-amplifying unit (21), a second contact of the second mode selection switch (S2) is connected to the output of the current-voltage conversion unit (22), and a third contact of the second mode selection switch (S2) is connected to the input of the filter unit (26).
7. Multifunction tester according to claim 6, characterized in that it comprises a housing (50), a display panel (51) and function keys (54) embedded on the housing (50);
the processing unit (25) further comprises a grounding parameter storage subunit (253), the grounding parameter storage subunit (253) is connected with the grounding parameter calculation subunit (252), the display panel (51) is connected with the grounding parameter storage subunit (253) and the grounding parameter calculation subunit (252), and the function key (54) is connected with the grounding parameter storage subunit (253) and the grounding parameter calculation subunit (252);
the excitation source (10) and the arithmetic processing module (20) are both located in the housing (50), and the plurality of wiring ports in the connection module (30) are both disposed on the surface of the housing (50).
8. The multi-function tester of claim 7, further comprising a mode selection knob (52) disposed on a surface of the housing (50), the mode selection knob (52) being connected to the excitation source control subunit (251) and the ground parameter calculation subunit (252), the mode selection knob (52) having a plurality of gear positions including at least one of an on-resistance measurement mode gear position (M1), a three-pole ground resistance measurement mode gear position (M2), a single-clamp ground resistance measurement mode gear position (M3), a double-clamp ground resistance measurement mode gear position (M4), a soil resistivity measurement mode gear position (M5), a power frequency ground voltage mode gear position (M6), and a power frequency current mode gear position (M7).
9. The multifunctional tester according to claim 7, further comprising a test key (53) disposed ON a surface of the housing (50), wherein the test key (53) is connected to the excitation source control subunit (251) and the grounding parameter calculation subunit (252), and the test key (53) has two stages of "ON" and "OFF".
10. A multifunctional test system comprising a multifunctional test meter according to any one of claims 1 to 9 and a probe.
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| CN202021262953.2U CN213398688U (en) | 2020-06-30 | 2020-06-30 | Multifunctional tester and testing system |
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| CN202021262953.2U CN213398688U (en) | 2020-06-30 | 2020-06-30 | Multifunctional tester and testing system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114325115A (en) * | 2021-12-29 | 2022-04-12 | 中国铁道科学研究院集团有限公司通信信号研究所 | Grounding performance detection device and method for building grounding system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114325115A (en) * | 2021-12-29 | 2022-04-12 | 中国铁道科学研究院集团有限公司通信信号研究所 | Grounding performance detection device and method for building grounding system |
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