CN107643440B - Detection device for human body power frequency induced current and application method thereof - Google Patents
Detection device for human body power frequency induced current and application method thereof Download PDFInfo
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Abstract
The invention discloses a detection device of human body power frequency induction current and an application method thereof, wherein the detection device comprises a current acquisition component, a signal cable, a current signal amplification detection unit and a grounding device, the current acquisition component comprises an upper layer metal plate, an intermediate layer insulating plate and a lower layer metal plate which are arranged in a stacking way, the current signal amplification detection unit comprises a metal shielding shell which is connected and conducted with a shielding shell of the signal cable, and a precise resistor Rx and an alternating current digital voltmeter which are arranged in parallel and are insulated and isolated from the metal shielding shell are arranged in the metal shielding shell; the application method comprises the step of extracting a microampere-level power frequency induction current signal under the interference of a high-frequency current signal based on the detection device. The invention can extract the microampere-level power frequency current signal with higher precision under the interference of the high-frequency current signal, and has the advantages of accurate and reliable detection, sensitive response, high resolution, strong anti-interference capability, simple wiring, low manufacturing cost and the like.
Description
Technical Field
The invention relates to the electric power engineering technology, in particular to a detection device for human body power frequency induced current and an application method thereof.
Background
The high-voltage overhead transmission line can generate an electric field in the space around the electrified conductor, and objects (especially objects with higher conductivity, including human bodies) in the power frequency electric field can generate electric potential rise of tens to tens of kilovolts under the action of the power frequency electric field. When the human body is insulated from other objects and the ground, partial free charges in the human body move to the ground through a loop formed by coupling the distributed capacitance of the human body to the human body, the human body and the distributed capacitance of the human body to the ground through a circuit, so that continuous power frequency induction current is generated in the human body; when the human body keeps contact with other induced objects, if the potential of other induced objects is higher than the potential of the human body, the free charge of the induced objects is coupled to the induced objects through a circuit to form a loop of the induced object coupling distributed capacitance, the human body and the human body to the ground distributed capacitance, and indirect induced current is generated in the human body and combined with the induced current of the human body to generate total induced current. Under the action of power frequency electric field, a potential difference of several kilovolts can be generated between human body and earth or between human body and sensed object, natural air gaps exist in the contact surface of human body and sensed object or earth, under the action of potential difference of several kilovolts, the air gaps are subjected to the cyclic reciprocating charge-discharge process of breakdown-arc extinction-charge-breakdown, and according to the size of the air gaps, the frequency of discharge current can reach hundred megahertz, so that a large amount of high-frequency components are added in the human body sensing current.
The human body surface-to-ground stray capacitance approximately corresponds to a short circuit for high-frequency current, and high-frequency current components easily form a loop through the human body surface-to-ground stray capacitance and basically do not pass through internal tissues of the human body, so that the human body is less damaged; however, the stray capacitance of the human body surface to the ground is equivalent to an open circuit, the internal resistance of the human body in kiloohms is approximately equivalent to a short circuit to the power frequency current component, and most of the power frequency current component can enter the ground only after penetrating through important organs such as heart and the like in the human body, so that the damage possibly caused by the power frequency current component to the human body is far greater than that of the high frequency component. GB/T13870.1-2008 first part of the effect of current on humans and livestock: the effect of power frequency current on human body is discussed in detail in general part, and the power frequency current with the effective value of 500 mu A is recommended to be the reaction current threshold value of the human body, and the power frequency current with the effective value of 5000 mu A is recommended to be the break-away current threshold value of the human body. Therefore, accurate and quantitative detection of human body power frequency induction current is important to ensure the safety and health of residents around the power transmission line, and has very important guiding significance to the field intensity control design of the power transmission line.
In the technical field of electrician/electronics, an alternating current effective value flowing through a certain branch can be conveniently detected through an alternating current meter; or the current transformer is used for collecting an alternating current signal of a certain branch and is connected with the oscilloscope, so that the current waveform of the branch can be conveniently observed, and the technology in the field can be used for detecting the induced current of the human body. However, in the technical field of electrician/electronics, the effective value of microampere-level alternating current can be detected by an alternating current ammeter, but high-frequency components in the induced current cannot be filtered; the power frequency signal of the branch current can be acquired through the low-pass current transformer, but the current precision of the microampere level is poor. At present, no technical proposal which can simultaneously remove the interference of high-frequency current components and accurately test the power frequency current components is disclosed in the related technical field.
In summary, the disadvantage of the existing method is that the microampere-level power frequency current signal cannot be extracted with high accuracy under the interference of the high frequency current signal.
Disclosure of Invention
The invention aims to solve the technical problems: aiming at the problems in the prior art, the invention provides the detection device for the human body power frequency induction current and the application method thereof, which can effectively filter out the high-frequency interference signal generated by the transient electric shock in the human body induction current signal under the environment of high electric field intensity, amplify the power frequency current signal of microampere level, accurately and quantitatively detect the effective value of the power frequency induction current flowing through the human body, extract the power frequency current signal of microampere level with higher precision under the interference of the high-frequency current signal, and have the advantages of accurate and reliable detection, sensitive response, high resolution, strong anti-interference capability, simple wiring, low manufacturing cost and the like.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a detection device for human body power frequency induced current, which comprises a current acquisition component, a signal cable, a current signal amplification detection unit and a grounding device, wherein the current acquisition component comprises an upper layer metal plate, an intermediate layer insulating plate and a lower layer metal plate which are sequentially and fixedly connected with each other, the signal cable comprises an inner core and a shielding shell which are mutually insulated and isolated, the inner core of the upper layer metal plate is connected and conducted with the inner core of the signal cable, the shielding shell of the lower layer metal plate is connected and conducted with the shielding shell of the signal cable and grounded, the current signal amplification detection unit comprises a metal shielding shell which is connected and conducted with the shielding shell of the signal cable, a precise resistor Rx and an alternating current digital voltmeter which are mutually and parallelly arranged and are respectively kept insulated and isolated with the metal shielding shell are arranged in the metal shielding shell, and a positive terminal of the alternating current digital voltmeter is connected and conducted with the inner core of the signal cable and a negative terminal of the alternating current digital voltmeter is grounded through a wire with an insulating surface and a grounding device.
Preferably, the dielectric constant of the interlayer insulating plate is 3-4, and the equivalent lumped parameter capacitance Cx formed by sequentially stacking the upper layer metal plate, the interlayer insulating plate and the lower layer metal plate is 100 pF-10 nF.
Preferably, the resistance value of the precision resistor Rx is between 10kΩ and 1000kΩ.
Preferably, the upper metal plate and the lower metal plate are both aluminum plates.
Preferably, the interlayer insulating plate is an epoxy insulating plate.
Preferably, the upper layer metal plate, the middle layer insulating plate and the lower layer metal plate are square plates.
Preferably, the grounding device is a grounding copper rod.
The invention provides an application method of the detection device for the human body power frequency induction current, which comprises the following implementation steps:
1) The resistance value of the precise resistor Rx is selected in advance according to the sensed object, the detection device for the human body power frequency induction current is arranged on the lower side of the three-phase high-voltage transmission line based on the precise resistor Rx with the selected resistance value, and the current acquisition assembly is placed on the ground;
2) The tester holds the sensed object standing on the current acquisition component and keeps natural contact with the sensed object;
3) The power frequency induction current which flows into the human body of the tester indirectly through the contact surface of the human body and the sensed object is collected on an upper metal plate, the induction current which flows into the human body of the tester indirectly through the contact surface of the human body and the sensed object indirectly through the coupling distribution capacitor C1 between the high-voltage transmission line and the sensed object indirectly flows into the human body of the tester indirectly through the contact surface of the human body and the sensed object, and the induction current which flows into the human body of the tester directly through the coupling distribution capacitor C2 between the high-voltage transmission line and the tester takes the power frequency component as the main component;
4) The ground capacitance Cx of the current collection assembly is approximately short-circuited to high-frequency current, most of high-frequency current components are directly led into the ground through the ground capacitance Cx, meanwhile, power frequency current components are led into the ground through a signal cable, a current signal amplification detection unit and a grounding device in sequence, and finally, the high-frequency current components flow back to the power transmission line through a neutral point of the three-phase high-voltage power transmission line;
5) The precise resistor Rx converts the flowing current into voltage signals at two ends and amplifies the voltage signals at two ends, the voltage signals are respectively connected into the positive terminal and the negative terminal of the alternating current digital voltmeter through annealed copper wires with insulating skins, and the effective value U of the alternating current voltage is detected through the alternating current digital voltmeter x And displaying the output;
6) According to the resistance value of the precision resistor Rx, the effective value U of the alternating voltage is obtained x Effective value I converted into power frequency induction current flowing through human body of tester x 。
Preferably, the specific step of selecting the resistance value of the precision resistor Rx according to the sensed object in step 1) includes:
1.1 Connecting the sensed object with the positive terminal of the alternating current digital ammeter, connecting the negative terminal of the alternating current digital ammeter with a grounding device, and reading the effective value of the short-circuit current of the sensed object;
1.2 Selecting the resistance value of the precision resistor Rx according to the effective value of the short-circuit current of the sensed object: when the short-circuit current test value of the sensed object is smaller than 0.1mA, selecting the resistance value of the precision resistor Rx to be 1000kΩ; when the short-circuit current test value of the sensed object is 0.1-1 mA, selecting the resistance value of the precision resistor Rx to be 100kΩ; when the short-circuit current test value of the sensed object is larger than 1mA, the resistance value of the precision resistor Rx is selected to be 10kΩ.
Preferably, in step 5), the effective value U of the alternating voltage is set x Effective value I converted into power frequency induction current flowing through human body of tester x When the resistance value of the precision resistor Rx is 1000kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is Ux; if the resistance value of the precision resistor Rx is 100kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is 10 XUx; if the resistance value of the precision resistor Rx is 10kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is 100 XUx, wherein U x Is an effective value of an alternating voltage output by an alternating digital voltmeter (32).
The detection device for the human body power frequency induction current has the following advantages: the detection device for the human body power frequency induction current can accurately amplify and collect the power frequency current signal of microampere level from the high-frequency and power frequency mixed current, the effective value of the power frequency current measured by the detection device can provide accurate and quantitative data reference for the safety evaluation of a human body in a strong power frequency electric field, can effectively filter out high-frequency interference signals generated by transient electric shock in the human body induction current signal in a high-electric field strength environment, can amplify the power frequency current signal of microampere level, can accurately and quantitatively detect the effective value of the power frequency induction current flowing through the human body, can extract the power frequency current signal of microampere level with higher accuracy under the interference of the high-frequency current signal, and has the advantages of strong anti-interference capability, high detection accuracy, high resolution, convenience in carrying, low manufacturing cost and the like.
The application method of the detection device for the human body power frequency induction current is the application of the detection device for the human body power frequency induction current, can accurately amplify and collect the power frequency current signal of microampere level from the high-frequency and power frequency mixed current, can provide accurate and quantitative data reference for the safety evaluation of the human body under the strong power frequency electric field, can effectively filter out the high-frequency interference signal generated by transient electric shock in the human body induction current signal under the high electric field intensity environment, can amplify the power frequency current signal of microampere level, can accurately and quantitatively detect the effective value of the power frequency induction current flowing through the human body, can extract the power frequency current signal of microampere level with higher precision under the interference of the high-frequency current signal, and has the advantages of strong anti-interference capability, accurate detection, high resolution and the like.
Drawings
Fig. 1 is a schematic diagram of an application principle of a detection device according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a detection device according to an embodiment of the invention.
Fig. 3 is a basic flow chart of an application method of the embodiment of the invention.
Fig. 4 is a waveform of a total current flowing through a human body according to an embodiment of the present invention.
Fig. 5 is a waveform of a test of a current flowing through a human body power frequency induction current according to an embodiment of the present invention.
Detailed Description
The device for detecting the human body power frequency induction current and the application method thereof are further described in detail below by taking an induced charged object as an example of a metal skeleton umbrella positioned right below a 500kV compact power transmission line.
As shown in fig. 1 and 2, the detection device for human body power frequency induced current of the present embodiment includes a current collecting component 1, a signal cable 2, a current signal amplifying detection unit 3 and a grounding device 4, the current collecting component 1 includes an upper layer metal plate 11, an intermediate layer insulating plate 12 and a lower layer metal plate 13 which are sequentially stacked and fastened and connected with each other, the signal cable 2 includes an inner core and a shielding shell which are insulated and isolated from each other, the inner core connection of the upper layer metal plate 11 and the signal cable 2 is conducted, the lower layer metal plate 13 and the shielding shell connection of the signal cable 2 is conducted and grounded, the current signal amplifying detection unit 3 includes a metal shielding shell 31 which is connected and conducted with the shielding shell connection of the signal cable 2, a precision resistor Rx and an ac digital voltmeter 32 which are arranged in parallel and are all kept insulated and isolated from the metal shielding shell 31 are arranged in the metal shielding shell 31, a positive terminal of the ac digital voltmeter 32 is connected and conducted with the inner core connection of the signal cable 2, and a negative terminal is grounded through a wire 321 with an insulating skin, and the grounding device 4. In fig. 1, C1 represents a coupling distribution capacitance between the high-voltage power transmission line and the induced object, C2 represents a coupling distribution capacitance between the high-voltage power transmission line and the human body, C3 represents a ground distribution capacitance of the induced charged object, C4 represents a human body equivalent circuit (which cannot be quantified and is therefore represented by a black box model), C5 represents a human body and induced object contact surface equivalent circuit (which cannot be quantified and is therefore represented by a black box model), cx represents a ground equivalent capacitance of the current acquisition module 1, and Rx represents a precision resistance of the current signal amplification detection unit 3. It is noted that all lumped capacitance parameters in fig. 1 represent in principle only equivalent electrical characteristics of the system and do not represent the actual loop of the system.
As shown in fig. 2, the current collecting assembly 1 includes an upper metal plate 11, an intermediate insulating plate 12 and a lower metal plate 13 which are sequentially stacked and fastened to each other, and the upper metal plate 11, the intermediate insulating plate 12 and the lower metal plate 13 are fastened by screws at four corners to form an equivalent capacitance Cx and simultaneously serve as a mechanical support structure. The dielectric constant of the intermediate insulating plate 12 is generally 3-4, in this embodiment, the dielectric constant of the intermediate insulating plate 12 is 4, and the equivalent lumped parameter capacitance Cx formed by sequentially stacking the upper layer metal plate 11, the intermediate insulating plate 12 and the lower layer metal plate 13 is 100 pF-10 nF. The upper metal plate 11 and the lower metal plate 13 are both aluminum plates. In this embodiment, the interlayer insulating plate 12 is an epoxy insulating plate. The upper layer metal plate 11, the middle layer insulating plate 12 and the lower layer metal plate 13 are square plates with specific thickness of 2.5mm, the areas of the upper layer metal plate 11 and the lower layer metal plate 13 are 336mm multiplied by 336mm,
in this embodiment, the resistance of the precision resistor Rx is between 10kΩ and 1000kΩ.
In this embodiment, the ac digital voltmeter 32 is a Fluke digital multimeter ac mA gear.
In this embodiment, the grounding device 4 is a grounding copper rod.
The working principle of the detection device for human body power frequency induction current of the embodiment is as follows: the tester stands on the upper aluminum metal plate of the current collection assembly 1 and keeps natural contact with the induced charged object, see figure 1, three parts of power frequency induction current which flows through the human body of the tester are gathered on the upper metal plate 11 through the power frequency induction current which flows through the coupling distributed capacitance C1 (equivalent lumped parameter) between the high voltage transmission line and the induced object and indirectly flows into the human body of the tester through the contact surface of the human body and the induced object, and the power frequency induction current which flows into the human body of the tester through the coupling distributed capacitance C2 (equivalent lumped parameter) between the high voltage transmission line and the tester, the coupling distributed capacitance C1 indirectly flows into the human body of the tester through the contact surface of the human body and the induced object, the induced current which directly flows into the human body of the tester through the coupling distributed capacitance C2 takes the power frequency component as the main component, the grounding capacitance Cx (equivalent lumped parameter) of the current collection component 1 approximately short-circuits the high-frequency current to the ground, most of the high-frequency current component can be directly led into the ground through Cx, the power frequency current component enters the ground through the precise resistor Rx (concentrated parameter element) of the current signal amplification detection unit 3 and is collected and converted and amplified into a voltage signal with proper size for being detected and displayed by the AC digital voltmeter 32, thus the power frequency signal with microampere level can be accurately amplified and collected from the high-frequency and power frequency mixed current, and the coupling distributed capacitance C1 has strong anti-interference capability and accurate detection, the power frequency current effective value measured by the detection device can provide accurate and quantitative data reference for the safety evaluation of human bodies in a strong power frequency electric field.
Referring to fig. 1, in the testing process of the embodiment, the high-voltage transmission line indirectly transmits a part of induction current to the human body through coupling capacitances C11, C12 and C13 between the line and the sensed object, the contact surface between the human body and the sensed object, the human body of the tester and a loop formed by the ground; in the process, because a large number of tiny air gaps exist at the contact surface between the human body and the sensed object, the induced current cannot pass through an effective contact point and can be transmitted into the human body through a contact gap capacitor, and the tiny air gaps continuously generate a breakdown-arc quenching-charging-breakdown charging and discharging process (namely a transient electric shock phenomenon) under the action of the potential difference between the human body and the sensed object, so that a large amount of high-frequency components are doped in the induced current; the currents of the high-frequency components and the indirect power frequency induction currents are respectively converged into an upper aluminum metal plate 11 of the current acquisition assembly 1 through human body ground stray capacitance and human body internal tissues; in addition, the high-voltage transmission line directly transmits the other part of induced current to the human body through coupling capacitors C21, C22 and C23 between the line and the tester, and the human body of the tester and a loop formed by the ground, and the induced current is converged into the upper-layer aluminum metal plate 11 of the current acquisition assembly 1 through the internal tissue of the human body; therefore, the upper aluminum metal plate 11 of the current collection assembly 1 collects three components including direct power frequency induction current, indirect power frequency induction current and high-frequency transient electric shock current. The numerical value of the equivalent capacitance Cx formed by the current acquisition component 1 can be adjusted by reasonably designing the area of the upper aluminum metal plate 11 and the lower aluminum metal plate 13, the thickness, the dielectric constant and other parameters of the middle epoxy resin insulating plate 12, so that the equivalent capacitance Cx leads most of high-frequency components in the three parts of current to be short-circuited and then led into the ground; by reasonably setting the value of the precision resistor Rx 22 in the current signal amplification detection unit 3, the power frequency current component of the residual microampere level can be accurately converted and amplified into a voltage signal with proper size for detection and display by the alternating current digital voltmeter 32. The equivalent circuit formed by connecting the equivalent capacitance Cx and the precise resistor Rx in parallel is in series connection with the C1, C2, the equivalent circuit of the contact gap between the human body and the sensed object and the equivalent circuit of the human body of the tester, and only the total current of the ground is screened.
Referring to fig. 3, the implementation steps of the application method of the detection device for human body power frequency induction current in this embodiment include:
1) The resistance value of the precise resistor Rx is selected in advance according to the sensed object, the detection device for the human body power frequency induction current of the embodiment is arranged on the lower side of the three-phase high-voltage transmission line based on the precise resistor Rx with the selected resistance value, and the current acquisition assembly 1 is placed on the ground;
2) The tester holds the sensed object standing on the current acquisition component 1 and keeps natural contact with the sensed object;
3) Referring to fig. 1, three current components of the power frequency induction current flowing through the upper metal plate 11 are collected, the induction current flowing through the contact surface of the human body and the induced object indirectly into the human body of the tester contains a power frequency component and a high frequency component, and the induction current flowing through the contact surface of the human body and the induced object indirectly into the human body of the tester directly passes through the coupling distribution capacitor C2 (equivalent lumped parameter) between the high voltage transmission line and the induced object, and the coupling distribution capacitor C2 directly passes through the induction current flowing through the human body of the tester mainly comprises the power frequency component;
4) The approximate short circuit of the grounding capacitance Cx of the current collection assembly (1) to the high-frequency current leads most of the high-frequency current component to the ground directly through the grounding capacitance Cx, and simultaneously leads the power frequency current component to the ground sequentially through the signal cable 2, the current signal amplification detection unit 3 and the grounding device 4, and finally flows back to the power transmission line through the neutral point of the three-phase high-voltage power transmission line;
5) The precision resistor Rx converts the flowing current into a voltage signal at two endsThe voltage signals at the two ends are respectively connected into the positive terminal and the negative terminal of the alternating current digital voltmeter 32 through the annealed copper wires with insulating skins, and the effective value U of the alternating current voltage is detected through the alternating current digital voltmeter 32 x And displaying the output;
6) According to the resistance value of the precision resistor Rx, the effective value U of the alternating voltage is obtained x Effective value I converted into power frequency induction current flowing through human body of tester x 。
It should be noted that the equivalent lumped parameter may be generally understood as an equivalent parameter. Countless stray distributed capacitances exist between the three phases of the high-voltage transmission line and the human body and between the high-voltage transmission line and an object to be sensed (such as an umbrella with a metal framework), and the capacitances cannot be calculated quantitatively and are not well described even in qualitative analysis. Considering that an umbrella of a power transmission line and a metal framework is a metal object, after the umbrella is divided into a plurality of parts, the electric potentials of the parts are equal, which is the inherent characteristic of metal; the human body is not metal, but in practice, the electric potential difference of the parts on the surface of the human body is not large, and it is also possible to approximate the parts on the surface of the human body as equipotential. Under the assumption, a certain phase lead of the power transmission line, an umbrella with a metal framework and a human body can be directly equivalent to 3 nodes with different electric potentials in the circuit, and the capacitance between the nodes is the so-called lumped parameter capacitance. Since the detection of the present device does not depend on the assumptions above, the test results are not approximate, but accurate.
Referring to fig. 3, the specific step of selecting the resistance value of the precision resistor Rx according to the sensed object in step 1) includes:
1.1 Connecting the sensed object with the positive terminal of the alternating current digital ammeter, connecting the negative terminal of the alternating current digital ammeter with a grounding device, and reading the effective value of the short-circuit current of the sensed object;
1.2 Selecting the resistance value of the precision resistor Rx according to the effective value of the short-circuit current of the sensed object: when the short-circuit current test value of the sensed object is smaller than 0.1mA, selecting the resistance value of the precision resistor Rx to be 1000kΩ; when the short-circuit current test value of the sensed object is 0.1-1 mA, selecting the resistance value of the precision resistor Rx to be 100kΩ; when the short-circuit current test value of the sensed object is larger than 1mA, the resistance value of the precision resistor Rx is selected to be 10kΩ.
In the present embodiment, in step 5), the effective value U of the alternating voltage is set x Effective value I converted into power frequency induction current flowing through human body of tester x When the resistance value of the precision resistor Rx is 1000kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is Ux; if the resistance value of the precision resistor Rx is 100kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is 10 XUx; if the resistance value of the precision resistor Rx is 10kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is 100 XUx, wherein U x Is an effective value of an alternating voltage output by an alternating digital voltmeter (32).
In the embodiment, a Fluke digital multimeter alternating current mA gear is adopted as an alternating current digital voltmeter 32 to test the short-circuit current of the sensed object, and the effective value of the short-circuit current of the sensed object is measured to be 0.124mA, namely 124 mu A; selecting a resistance value of the precision resistor Rx as rx=100 k Ω; in the present embodiment, the display data of the ac digital voltmeter 32 is U x The test value (effective value) of the power frequency induction current actually flowing through the tester is I x =10 3 ×U x /R x =10 3 X 15.63/100=156.3 μa. Therefore, the detection device for the human body power frequency induction current and the application method thereof can overcome the high-frequency current interference and accurately collect the power frequency current signal, and have the advantages of accuracy, reliability, sensitive response and high resolution.
In order to verify the detection performance of the detection device for the human body power frequency induced current in the embodiment, the output signal comparison test of the current signal amplification device is performed in the embodiment:
s1) short-circuiting the positive terminal and the negative terminal of a current signal amplification detection unit 3, sleeving a broadband current transformer on a annealed copper wire 321 with an insulating surface, collecting an original current signal waveform of the total current flowing through a human body when the detection device of the human body power frequency induction current in the embodiment is not connected with the detection device through an oscilloscope, wherein the original current signal waveform contains a large amount of high-frequency interference components due to the influence of high-frequency current components in the human body induction current, namely a large amount of burrs appear on the waveform as shown in FIG. 4;
s2) normally accessing the detection device for the human body power frequency induction current of the embodiment according to the steps 1) and 2), accessing a signal of the positive terminal of the current signal amplification detection unit 3 to an oscilloscope through a voltage probe, collecting a voltage signal waveform of the positive terminal of the detection device for the human body power frequency induction current of the embodiment, reducing the voltage signal waveform into an actual power frequency induction current waveform according to amplification factors, comparing the actual power frequency induction current waveform with the actual power frequency induction current waveform shown in fig. 5, and finding that the standard sinusoidal power frequency induction current waveform is shown in fig. 5, wherein high-frequency current components in the human body induction current are basically eliminated;
s3) carrying out subsequent analysis according to the data acquired by the oscilloscope, wherein the effective value of the waveform corresponding to FIG. 4 is 744.2 mu A, which is far greater than the value 156.3 mu A measured by the induction current detection device, and the effective value of the waveform corresponding to FIG. 5 is 156.1 mu A, which is basically consistent with the value 156.3 mu A measured by the human body power frequency induction current detection device in the embodiment.
Through verification, the detection device for the human body power frequency induction current can effectively eliminate high-frequency current components in the human body induction current, can effectively filter high-frequency interference signals generated by transient electric shock in human body induction current signals under a high electric field intensity environment, amplifies the microampere-level power frequency current signals, can accurately and quantitatively detect effective values of the flowing human body power frequency induction current, and has the advantages of being accurate in detection, high in resolution, strong in anti-interference capability, simple in wiring, low in manufacturing cost and the like.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.
Claims (9)
1. An application method of a detection device for human body power frequency induction current is characterized in that: the detection device for the human body power frequency induced current comprises a current acquisition component (1), a signal cable (2), a current signal amplification detection unit (3) and a grounding device (4), wherein the current acquisition component (1) comprises an upper metal plate (11), an intermediate insulating plate (12) and a lower metal plate (13) which are sequentially arranged in a stacked mode and are mutually and tightly connected, the signal cable (2) comprises an inner core and a shielding shell which are mutually insulated and isolated, the inner core of the upper metal plate (11) and the inner core of the signal cable (2) are connected and conducted, the lower metal plate (13) and the shielding shell of the signal cable (2) are connected and conducted and grounded, the current signal amplification detection unit (3) comprises a metal shielding shell (31) which is connected and conducted with the shielding shell of the signal cable (2), a precise resistor and an alternating current digital voltmeter (32) which are mutually and tightly arranged in parallel and are respectively kept insulated and isolated with the metal shielding shell (31) are arranged in the metal shielding shell (31), and a positive terminal and a negative terminal of the alternating current digital voltmeter (32) are connected and conducted with the inner core of the signal cable (2) and conducted, a negative terminal of the shielding shell is connected and grounded through a wire (321) and a grounding device (4); the application method comprises the following implementation steps:
1) The method comprises the steps that the resistance value of a precision resistor Rx is selected in advance according to an object to be sensed, a detection device for the human body power frequency induction current is arranged on the lower side of a three-phase high-voltage transmission line based on the precision resistor Rx with the selected resistance value, and a current acquisition assembly (1) is placed on the ground;
2) The tester holds the sensed object to stand on the current acquisition component (1) and keeps natural contact with the sensed object;
3) The power frequency induction current which flows into the human body of the tester through the coupling distribution capacitor C1 between the high-voltage transmission line and the induced object and indirectly flows into the human body of the tester through the contact surface of the human body and the induced object, the high-frequency induction current which flows into the human body of the tester through the coupling distribution capacitor C1 between the high-voltage transmission line and the induced object and indirectly flows into the human body of the tester through the contact surface of the human body and the induced object, the power frequency induction current which flows into the human body of the tester through the coupling distribution capacitor C2 between the high-voltage transmission line and the induced object is concentrated on an upper metal plate (11), the induction current which flows into the human body of the tester through the contact surface of the human body and the induced object indirectly contains a power frequency component and a high frequency component, and the induction current which flows into the human body of the tester through the coupling distribution capacitor C2 is mainly the power frequency component;
4) The method comprises the steps that the ground capacitor Cx of a current collection assembly (1) is approximately short-circuited for high-frequency current, most of high-frequency current components are directly led into the ground through the ground capacitor Cx, meanwhile, power frequency current components are sequentially led into the ground through a signal cable (2), a current signal amplification detection unit (3) and a grounding device (4), and finally, the high-frequency current components flow back to a power transmission line through a neutral point of the three-phase high-voltage power transmission line;
5) The precision resistor Rx converts the flowing current into voltage signals at two ends and amplifies the voltage signals at two ends, the voltage signals are respectively connected into the positive terminal and the negative terminal of the alternating current digital voltmeter (32) through annealed copper wires with insulating skins, and the effective value U of the alternating current voltage is detected through the alternating current digital voltmeter (32) x And displaying the output;
6) According to the resistance value of the precision resistor Rx, the effective value U of the alternating voltage is obtained x Effective value I converted into power frequency induction current flowing through human body of tester x 。
2. The application method of the human body power frequency induction current detection device according to claim 1, wherein the application method is characterized in that: the dielectric constant of the middle-layer insulating plate (12) is 3-4, and the equivalent lumped parameter capacitance Cx formed by sequentially stacking the upper-layer metal plate (11), the middle-layer insulating plate (12) and the lower-layer metal plate (13) is 100 pF-10 nF.
3. The application method of the human body power frequency induction current detection device according to claim 1, wherein the application method is characterized in that: the resistance value of the precision resistor Rx is 10k omega-1000 k omega.
4. The application method of the human body power frequency induction current detection device according to claim 1, wherein the application method is characterized in that: the upper layer metal plate (11) and the lower layer metal plate (13) are both aluminum plates.
5. The application method of the human body power frequency induction current detection device according to claim 1, wherein the application method is characterized in that: the interlayer insulating board (12) is an epoxy resin insulating board.
6. The application method of the human body power frequency induction current detection device according to claim 1, wherein the application method is characterized in that: the upper layer metal plate (11), the middle layer insulating plate (12) and the lower layer metal plate (13) are square plates.
7. The application method of the human body power frequency induction current detection device according to claim 1, wherein the application method is characterized in that: the grounding device (4) is a grounding copper rod.
8. The method for applying the device for detecting human body power frequency induction current according to claim 1, wherein the specific step of selecting the resistance value of the precision resistor Rx according to the sensed object in step 1) comprises the following steps:
1.1 Connecting the sensed object with the positive terminal of the alternating current digital ammeter, connecting the negative terminal of the alternating current digital ammeter with a grounding device, and reading the effective value of the short-circuit current of the sensed object;
1.2 Selecting the resistance value of the precision resistor Rx according to the effective value of the short-circuit current of the sensed object: when the short-circuit current test value of the sensed object is smaller than 0.1mA, selecting the resistance value of the precision resistor Rx to be 1000kΩ; when the short-circuit current test value of the sensed object is 0.1-1 mA, selecting the resistance value of the precision resistor Rx to be 100kΩ; when the short-circuit current test value of the sensed object is larger than 1mA, the resistance value of the precision resistor Rx is selected to be 10kΩ.
9. The method of claim 8, wherein in step 5), the effective value U of the alternating voltage is set to x Conversion into effective power frequency induction current flowing through human body of testerValue I x When the resistance value of the precision resistor Rx is 1000kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is Ux; if the resistance value of the precision resistor Rx is 100kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is 10 XUx; if the resistance value of the precision resistor Rx is 10kΩ, the effective value Ix of the power frequency induction current flowing through the human body of the tester is 100 XUx, wherein U x Is an effective value of an alternating voltage output by an alternating digital voltmeter (32).
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