Non-contact AC loop voltage detection device and detection method

Abstract

The invention relates to a non-contact AC loop voltage detection device and detection method, and relates to the technical field of electric power, an electromagnetic induction wire clamp in the device is located in a preset range of a to-be-detected AC loop in a non-contact manner, and is used for transmitting the sensed potential of the to-be-detected AC loop to a signal conditioning module; the signal conditioning module amplifies the potential and transmits the potential to the signal processing module; the signal conditioning module comprises a first-stage amplifier and a second-stage amplifier which are connected through a first capacitor, the input end of the first-stage amplifier is connected with the electromagnetic induction wire clamp, the output end of the second-stage amplifier is connected with the signal processing module, and the signal conditioning module comprises a current source connected with the first-stage amplifier; and the signal processing module is used for comparing the received potential with a preset electromotive force threshold value, determining that the alternating current loop to be detected is abnormal when the potential is greater than the preset electromotive force threshold value, transmitting an alarm signal to the audible and visual alarm module, and driving the audible and visual alarm module to carry out abnormal alarm so as to detect whether the alternating current loop to be detected is abnormal or not.

Description

Technical Field

[0001] The present application relates to the field of electric power technology, and in particular to a non-contact AC circuit voltage detection device and detection method. Background Art

[0002] In the power system, the existence of parasitic circuits poses a serious threat to the safety and stable operation of the system. These hidden circuit paths may cause serious consequences such as relay malfunction, circuit breaker tripping, malicious misoperation, etc. There is an obvious technical gap in the related technology for monitoring AC string AC parasitic circuits in AC systems. Especially during power outage operations, if there are undetected AC parasitic circuits in the motor power supply and control power supply circuits, safety measures or electrical interlocks will fail, increasing the risk of malicious misoperation.

[0003] Therefore, it is particularly urgent to design an AC parasitic loop detection device. Summary of the invention

[0004] Based on this, it is necessary to provide a voltage detection device that can monitor the AC string AC parasitic loop in the AC system.

[0005] In a first aspect, the present application provides a non-contact AC circuit voltage detection device, including an electromagnetic induction clamp, a signal conditioning module, a signal processing module, and an acousto-optic alarm module;

[0006] The electromagnetic induction clamp is non-contactly located within a preset range of the AC circuit to be tested and is electrically connected to the signal conditioning module, and is used to transmit the sensed potential corresponding to the AC circuit to be tested to the signal conditioning module;

[0007] The signal conditioning module is used to amplify the received electric potential and transmit the amplified electric potential to the electrically connected signal processing module; wherein the signal conditioning module includes a first-stage amplifier and a second-stage amplifier electrically connected through a first capacitor, a signal input end of the first-stage amplifier is electrically connected to the electromagnetic induction clamp, a signal output end of the second-stage amplifier is electrically connected to the signal processing module, and the signal conditioning module also includes a current source electrically connected to the first-stage amplifier;

[0008] The signal processing module is used to compare the received electric potential with a preset electromotive force threshold value. When the comparison result indicates that the electric potential is greater than the preset electromotive force threshold value, it is determined that there is an abnormality in the AC circuit to be tested, and an alarm signal is transmitted to the sound and light alarm module to drive the sound and light alarm module to issue an abnormality alarm.

[0009] In one embodiment, the first stage amplifier includes a first transistor, a second transistor, a first resistor, a second resistor, a third resistor, a fourth resistor and a first amplifier;

[0010] The control electrode of the first transistor is electrically connected to the electromagnetic induction clamp, the first electrode of the first transistor is electrically connected to the first electrode of the second transistor, and the second electrode of the first transistor is electrically connected to the first end of the first resistor and the first input end of the first amplifier;

[0011] The second electrode of the second transistor is electrically connected to the first electrode of the second resistor and the second input terminal of the first amplifier, and the control electrode of the second transistor is electrically connected to the first end of the third resistor and the first end of the fourth resistor;

[0012] The second end of the first resistor and the second end of the second resistor are electrically connected to the first power supply end;

[0013] The second end of the third resistor and the output end of the first amplifier are electrically connected to the first plate of the first capacitor;

[0014] A second end of the fourth resistor is grounded.

[0015] In one embodiment, the second stage amplifier includes a second amplifier, a second capacitor, a fifth resistor, a sixth resistor, and a seventh resistor;

[0016] A first end of the fifth resistor is electrically connected to the second plate of the first capacitor, and a second end of the fifth resistor is electrically connected to the first input end of the second amplifier;

[0017] After the sixth resistor and the second capacitor are connected in parallel, they are electrically connected to the first input end of the second amplifier and the output end of the second amplifier;

[0018] The output end of the second amplifier is electrically connected to the signal processing module through the seventh resistor, and the second input end of the second amplifier is grounded.

[0019] In one embodiment, the current source includes a third transistor and a fourth transistor, an eighth resistor, a ninth resistor and a tenth resistor;

[0020] The first electrode of the third transistor is electrically connected to the first power supply terminal through the eighth resistor, and the first electrode is electrically connected to the control electrode of the third transistor and the control electrode of the fourth transistor; the second electrode of the third transistor is electrically connected to the second power supply terminal through the ninth resistor;

[0021] A first electrode of the fourth transistor is electrically connected to a first electrode of the first transistor, and a second electrode of the fourth transistor is electrically connected to the second power supply terminal through the tenth resistor.

[0022] In one embodiment, at least one of the first transistor and the second transistor is a junction field effect transistor.

[0023] In one embodiment, the third transistor and the fourth transistor are triodes of the same specification;

[0024] The calculation formula of the current value of the current source is: ; Wherein, R8 is the resistance value of the ninth resistor, R9 is the resistance value of the ninth resistor, R 10 is the resistance value of the tenth resistor, V DD is the input voltage value of the first power supply terminal, V SS is the input voltage value of the second power supply terminal, U BEO is the voltage value between the control electrode and the first electrode of the third transistor.

[0025] In one embodiment, the calculation formula of the source-drain current value of the first transistor is: .

[0026] In one embodiment, a power module is also included;

[0027] The power supply module is electrically connected to the signal conditioning module, the signal processing module and the sound and light alarm module respectively.

[0028] In one of the embodiments, the sound and light alarm module includes a piezoelectric buzzer, an LED indicator light and an alarm signal output relay; the alarm signal output relay closes contacts based on the alarm signal and transmits the alarm signal to a data storage module for storage.

[0029] In a second aspect, the present application further provides a non-contact AC circuit voltage detection method, which is applied to a non-contact AC circuit voltage detection device as described in any one of the first aspects; the device includes an electromagnetic induction clamp, a signal conditioning module, a signal processing module and an acousto-optic alarm module;

[0030] The method comprises:

[0031] The AC voltage of the AC circuit to be tested is detected by the electromagnetic induction clamp. When the AC voltage is detected, an electric potential corresponding to the AC circuit to be tested is generated, and the electric potential is transmitted to the signal conditioning module for amplification, and then transmitted to the electrically connected signal processing module; the signal processing module is driven to compare the received electric potential with a preset electromotive force threshold value. When the comparison result indicates that the electric potential is greater than the preset electromotive force threshold value, it is determined that the AC circuit to be tested is abnormal, and an alarm signal is transmitted to the sound and light alarm module, driving the sound and light alarm module to alarm for abnormality.

[0032] The present application provides a non-contact AC circuit voltage detection device and detection method, the voltage detection device includes an electromagnetic induction wire clamp, a signal conditioning module, a signal processing module and an acousto-optic alarm module; the electromagnetic induction wire clamp is non-contactly located within a preset range of the AC circuit to be tested, and is electrically connected to the signal conditioning module, and is used to transmit the sensed electric potential corresponding to the AC circuit to be tested to the signal conditioning module; the signal conditioning module is used to amplify the received electric potential, and transmit the amplified electric potential to the electrically connected signal processing module; wherein the signal conditioning module includes a first-stage amplifier and a second-stage amplifier electrically connected through a first capacitor, the signal input end of the first-stage amplifier is electrically connected to the electromagnetic induction wire clamp, and the signal output end of the second-stage amplifier is electrically connected to the signal processing module, The signal conditioning module also includes a current source electrically connected to the first-stage amplifier; the signal processing module is used to compare the received potential with a preset electromotive force threshold, and when the comparison result indicates that the potential is greater than the preset electromotive force threshold, it is determined that an abnormality exists in the AC circuit to be tested, and an alarm signal is transmitted to the sound and light alarm module to drive the sound and light alarm module to issue an abnormality alarm; this device detects whether there is an abnormality in the AC circuit to be tested in a non-contact manner, which can avoid the risk of reversely affecting the normal operation of the AC circuit to be tested due to the abnormality of the detection device, and when an abnormality is detected, an abnormality alarm can be automatically issued, thereby improving the practicability and safety of the detection device, and facilitating the manager of the AC circuit to be tested to find problems in a timely manner to improve the efficiency of problem solving. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 A schematic diagram of a non-contact AC circuit voltage detection device provided in an embodiment of the present application;

[0035] Figure 2 A circuit structure diagram of a signal conditioning module provided in an embodiment of the present application;

[0036] Figure 3 A schematic diagram of the working principle of the electromagnetic induction clamp provided in an embodiment of the present application;

[0037] Figure 4 A diagram showing the amplification effect of the signal conditioning module provided in an embodiment of the present application on the induced potential;

[0038] Figure 5 A working principle diagram of a non-contact AC circuit voltage detection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0042] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0043] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least part of an element” means part or all of an element.

[0044] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0045] In the power system, a parasitic circuit refers to a hidden circuit that should not exist in the secondary circuit due to design errors, improper wiring operations, moisture on relay contacts and terminals, or damaged circuit insulation. This abnormal circuit is difficult to detect during the normal operation of the power system.

[0046] The existence of parasitic circuits poses a serious threat to the system safety and stable operation of the power system. These hidden circuit paths may cause serious consequences such as relay malfunction, circuit breaker false tripping, malicious misoperation, etc. Although the existing DC insulation detection device can monitor the abnormal situation of AC series DC, there is an obvious technical gap in the monitoring of AC series AC parasitic circuits in low-voltage AC systems. Especially during power outage operations, if there are undetected AC parasitic circuits in the motor power supply and control power supply circuits, the safety measures or electrical interlocks will fail, which will increase the risk of malicious misoperation. In addition, in the related art, for the existing online monitoring devices for electrical quantities, their monitoring circuits often need to be directly connected to the secondary circuit of the equipment through wires, which increases the risk of grounding of the secondary circuit due to abnormal insulation of the device, which may affect the normal operation of the equipment.

[0047] Therefore, it is particularly urgent to design a non-contact AC parasitic circuit detection device, which can not only improve the operation and maintenance safety of the power system, but also provide key technical support for the operation and maintenance of unmanned substations.

[0048] Based on this, the present application provides a new type of non-contact detection device based on the principle of electromagnetic induction, which aims to timely discover hidden defects in the AC control circuit, thereby ensuring the reliable operation of the power system.

[0049] Please refer to Figure 1 and Figure 2 , In an exemplary embodiment, the present application provides a non-contact AC circuit voltage detection device, including an electromagnetic induction clamp 11, a signal conditioning module 12, a signal processing module 13 and an acousto-optic alarm module 14;

[0050] The electromagnetic induction clamp 11 is non-contactly located within a preset range of the AC circuit to be tested and is electrically connected to the signal conditioning module 12, and is used to transmit the sensed potential corresponding to the AC circuit to be tested to the signal conditioning module 12;

[0051] The signal conditioning module 12 is used to amplify the received electric potential and transmit the amplified electric potential to the electrically connected signal processing module 13; wherein the signal conditioning module 12 includes a first-stage amplifier 121 and a second-stage amplifier 122 electrically connected through a first capacitor C1, a signal input end of the first-stage amplifier 121 is electrically connected to the electromagnetic induction clamp 11, a signal output end of the second-stage amplifier 122 is electrically connected to the signal processing module 13, and the signal conditioning module 12 also includes a current source 123 electrically connected to the first-stage amplifier 121;

[0052] The signal processing module 13 is used to compare the received electric potential with the preset electromotive force threshold. When the comparison result indicates that the electric potential is greater than the preset electromotive force threshold, it is determined that there is an abnormality in the AC circuit to be tested, and an alarm signal is transmitted to the sound and light alarm module 14 to drive the sound and light alarm module 14 to issue an abnormal alarm.

[0053] Specifically, the contactless AC circuit voltage detection device provided in the present application may include an electromagnetic induction clamp 11, a signal conditioning module 12, a signal processing module 13 and an sound and light alarm module 14, wherein the signal output end of the electromagnetic induction clamp 11 is electrically connected to the signal input end of the signal conditioning module 12, the signal output end of the signal conditioning module 12 is electrically connected to the signal input end of the signal processing module 13, and the signal output end of the signal processing module 13 is electrically connected to the signal input end of the sound and light alarm module 14.

[0054] When using the non-contact AC circuit voltage detection device provided by the present application to perform voltage detection on the AC circuit, the electromagnetic induction clamp 11 can be placed next to the AC circuit to be tested, specifically, the electromagnetic induction clamp 11 can be placed within a preset range of the AC circuit to be tested, and the preset range is specifically a distance range in which the electric potential in the AC circuit to be tested can be sensed by the electromagnetic induction clamp 11. At the same time, the electromagnetic induction clamp 11 is not in direct contact with the AC circuit to be tested, so as to avoid the risk of grounding of the running AC circuit to be tested (secondary circuit) due to an abnormality in the voltage detection device, which may affect the normal operation of the power equipment corresponding to the AC circuit to be tested.

[0055] The signal conditioning module 12 is used to receive the potential in the AC circuit to be tested detected by the electromagnetic induction clamp 11 and perform signal conditioning such as amplification, and then transmit the potential after amplification and conditioning by the signal conditioning module 12 to the signal processing module 13 electrically connected to the signal conditioning module 12. Figure 2As shown, the present application also provides an optional implementation of a signal conditioning module, wherein the signal conditioning module 12 at least includes a first capacitor C 1、 The first stage amplifier 121, the second stage amplifier 122 and the current source 123 are electrically connected to both sides of the first capacitor C1, respectively, wherein the signal input end of the first stage amplifier 121 is electrically connected to the signal output end of the electromagnetic induction clamp 11, the signal output end of the second stage amplifier 122 is electrically connected to the signal processing module 13, and the current source 123 is electrically connected to the first stage amplifier 121. The current source 123 can at least provide a stable and appropriate static operating point for the transistor in the first stage amplifier 121, and can also improve the common mode rejection ratio of the first stage amplifier circuit.

[0056] The signal processing module 13 is used to receive the electric potential amplified and regulated by the signal conditioning module 12, and further compare the received electric potential (electromotive force) with a preset electromotive force threshold value, and the comparison result includes that the amplified electric potential corresponding to the measured AC circuit to be tested is greater than the preset electromotive force threshold value, or the amplified electric potential corresponding to the measured AC circuit to be tested is less than the preset electromotive force threshold value, or the amplified electric potential corresponding to the measured AC circuit to be tested is equal to the preset electromotive force threshold value; further, when the comparison result obtained indicates that the amplified electric potential corresponding to the measured AC circuit to be tested is greater than the preset electromotive force threshold value, it indicates that there is an abnormality in the AC circuit to be tested, and an alarm signal is generated at the same time, and the alarm signal is transmitted to the sound and light alarm module 14 electrically connected to the signal output end of the signal processing module 13, thereby driving the sound and light alarm module 14 to perform an abnormal alarm for the abnormality of the AC circuit to be tested, so that the manager of the power system of the AC circuit to be tested can find the problem in time, thereby improving the efficiency of solving abnormal problems.

[0057] The present application provides a non-contact AC circuit voltage detection device and detection method, the voltage detection device includes an electromagnetic induction clamp 11, a signal conditioning module 12, a signal processing module 13 and an acousto-optic alarm module 14; the electromagnetic induction clamp 11 is non-contactly located within a preset range of the AC circuit to be tested, and is electrically connected to the signal conditioning module 12, and is used to transmit the sensed electric potential corresponding to the AC circuit to be tested to the signal conditioning module 12; the signal conditioning module 12 is used to amplify the received electric potential and transmit the amplified electric potential to the electrically connected signal processing module 13; wherein the signal conditioning module 12 includes a first-stage amplifier 121 and a second-stage amplifier 122 electrically connected through a first capacitor C1, the signal input end of the first-stage amplifier 121 is electrically connected to the electromagnetic induction clamp 11, and the signal output end of the second-stage amplifier 122 is electrically connected to the The signal processing module 13 is electrically connected, and the signal conditioning module 12 also includes a current source 123 electrically connected to the first-stage amplifier 121; the signal processing module 13 is used to compare the received potential with a preset electromotive force threshold, and when the comparison result indicates that the potential is greater than the preset electromotive force threshold, it is determined that there is an abnormality in the AC circuit to be tested, and an alarm signal is transmitted to the sound and light alarm module 14 to drive the sound and light alarm module 14 to alarm for an abnormality; this device detects whether there is an abnormality in the AC circuit to be tested in a non-contact manner, which can avoid the risk of reversely affecting the normal operation of the AC circuit to be tested due to the abnormality of the detection device, and when an abnormality is detected, an abnormality alarm can be automatically issued, thereby improving the practicality and safety of the detection device, and facilitating the manager of the AC circuit to be tested to find problems in a timely manner to improve the efficiency of problem solving.

[0058] It should be explained that the electromagnetic induction clamp 11 uses the electromagnetic induction principle to detect the existence of a parasitic loop by inducing changes in the magnetic field. The schematic diagram is shown in FIG. Figure 3 As shown, according to Faraday's law, the alternating magnetic field will induce an electric potential in the electromagnetic induction clamp 11. The number of turns of the clamp induction coil affects the magnitude of the electric potential. By adjusting the number of turns of the coil and the position of the electromagnetic induction clamp 11, the sensitivity of the AC voltage detection in the parasitic loop can be improved.

[0059] In an exemplary embodiment, Figure 2As shown, a circuit structure design that can be selected for a signal conditioning module is provided, specifically, the first-stage amplifier 121 includes a first transistor J1, a second transistor J2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first amplifier U1; the control electrode of the first transistor J1 is electrically connected to the electromagnetic induction clamp 11, the first electrode of the first transistor J1 is electrically connected to the first electrode of the second transistor J2, and the second electrode of the first transistor J1 is electrically connected to the first end of the first resistor R1 and the first input end of the first amplifier U1; the second electrode of the second transistor J2 is electrically connected to the first electrode of the second resistor R2 and the second input end of the first amplifier U1, and the control electrode of the second transistor J2 is electrically connected to the first end of the third resistor R3 and the first end of the fourth resistor R4; the second end of the first resistor R1 and the second end of the second resistor R2 are electrically connected to the first power supply terminal V DD The second end of the third resistor R3 and the output end of the first amplifier U1 are electrically connected to the first plate of the first capacitor C1; the second end of the fourth resistor R4 is grounded.

[0060] The second-stage amplifier 122 includes a second amplifier U2, a second capacitor C2, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7; the first end of the fifth resistor R5 is electrically connected to the second plate of the first capacitor C1, and the second end of the fifth resistor R5 is electrically connected to the first input end of the second amplifier U2; after the sixth resistor R6 and the second capacitor C2 are connected in parallel, they are electrically connected to the first input end of the second amplifier U2 and the output end of the second amplifier U2; the output end of the second amplifier U2 is electrically connected to the signal processing module 13 through the seventh resistor R7, and the second input end of the second amplifier U2 is grounded.

[0061] The current source 123 includes a third transistor Q1, a fourth transistor Q2, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R 10 The first electrode of the third transistor Q1 is connected to the first power supply terminal V through the eighth resistor R8. DD The first electrode of the third transistor Q1 is electrically connected to the control electrode of the third transistor Q1 and the control electrode of the fourth transistor Q2; the second electrode of the third transistor Q1 is electrically connected to the second power supply terminal V through the ninth resistor R9. SS The first electrode of the fourth transistor Q2 is electrically connected to the first electrode of the first transistor J1, and the second electrode of the fourth transistor Q2 is electrically connected to the first electrode of the first transistor J1 through the tenth resistor R 10 The second power supply terminal V SS Electrical connection.

[0062] In an exemplary embodiment, at least one of the first transistor J1 and the second transistor J2 is a junction field effect transistor. The third transistor Q1 and the fourth transistor Q2 are triodes of the same specification.

[0063] For the signal conditioning module 12 provided in the present application, the present application also provides an optional implementation mode, in which the signal conditioning module 12 uses a low-noise preamplifier circuit to amplify the potential induced by the induction clamp to ensure that the detected weak voltage can be accurately analyzed by the subsequent signal processing module 13. The amplification circuit structure diagram is shown in FIG. Figure 2 As shown, the magnification effect is as follows Figure 4 shown.

[0064] The amplifier circuit is designed based on JFET (Junction Field-Effect Transistor), and the first-stage amplifier 121 is a differential amplifier circuit composed of two JFET differential pairs (J1 and J2) and an integrated operational amplifier (first amplifier U1). The sources of the two JFET differential pairs are connected to a current source 123 of Is, which not only provides a stable and suitable static operating point for the JFET, but also plays a role in improving the common-mode rejection ratio of the amplifier circuit.

[0065] In the input stage amplifier circuit (first stage amplifier 121), when transistors Q1 and Q2 are completely consistent and their current amplification factors are large, the current value of the current source 123 is calculated as follows: ; Wherein, R8 is the resistance value of the eighth resistor, R9 is the resistance value of the ninth resistor, R 10 is the resistance value of the tenth resistor, V DD The first power supply terminal (V DD ) input voltage value, V SS The second power supply terminal (V SS ) input voltage value, U BEO is the voltage value between the control electrode and the first electrode of the third transistor Q1, that is, the voltage between the base and the emitter of the transistor.

[0066] There is also provided an optional implementation mode in which the calculation formula of the current source 123 is: .

[0067] The calculation formula of the source-drain current value of the first transistor J1 is: .

[0068] Specifically, the source-drain current corresponding to the quiescent operating point of the JFET is: .

[0069] Furthermore, the input stage amplifier (first stage amplifier 121) adopts a series voltage negative feedback method to obtain a fixed 50-fold linear gain, while enhancing the stability of the amplifier circuit. The second stage amplifier 122 is an active low-pass filter based on an integrated operational amplifier. This stage amplifier circuit can provide a fixed gain of 20 times while filtering out high-frequency noise. The input stage amplifier (first stage amplifier 121) and the output stage amplifier (second stage amplifier 122) are coupled by a capacitor (first capacitor C1) to reduce the influence of the DC voltage of the input stage amplifier on the output stage amplifier. The signal conditioning module 12 is characterized by high input impedance and low noise, which is particularly important for processing weak signals.

[0070] In the second stage amplifier 122, the high-pass filter formed by the fifth resistor R5 and the first capacitor C1, and the low-pass filter formed by the sixth resistor R6, the second capacitor C2, and the second amplifier U2 form a band-pass filter, and the calculation formula of the lower limit cut-off frequency is: , the upper cut-off frequency is calculated as: , and the calculation formula of the gain of this stage amplifier circuit at the flat point is: .

[0071] It can be calculated that the lower cutoff frequency of the amplifier circuit is f L =100Hz (Hertz), the upper cutoff frequency is f H =1MHz (megahertz), that is, the theoretical bandwidth of the amplifier circuit is 100Hz~1MHz, and it provides a stable gain of 60dB (decibel) within the bandwidth, and the amplification factor can reach 100 times.

[0072] In an exemplary embodiment, the signal processing module 13 can be a single-chip microcomputer that performs signal processing, compares the amplified electromotive force with the nominal electric field measurement value, and determines whether the potential value exceeds a threshold value. If it exceeds, it indicates that the detected circuit is abnormally energized, and there may be an electrical fault or a parasitic circuit. At this time, the signal processing module 13 triggers the sound and light alarm module 14.

[0073] In an exemplary embodiment, the sound and light alarm module 14 is composed of a piezoelectric buzzer, a high-brightness LED (Light Emitting Diode) indicator light, and an alarm signal output relay. The piezoelectric buzzer can produce clear sound alarms in various environments due to its low power consumption and high sound pressure characteristics, while the high-brightness LED light ensures visual prominence, especially under strong light. When the sound and light alarm module 14 is activated, it will drive the alarm signal output relay, and after the contacts of the relay are closed, the alarm signal will be transmitted to the corresponding measurement and control device (data storage module). Among them, the measurement and control device is used to collect data.

[0074] In an exemplary embodiment, the contactless AC circuit voltage detection provided by the present application further includes a power module 15; the power module 15 is electrically connected to the signal conditioning module 12, the signal processing module 13 and the sound and light alarm module 14. The power module 15 can be composed of a rechargeable battery for powering the device.

[0075] It can be understood that the specific circuit structure involved in the above-mentioned non-contact AC circuit voltage detection device can also adopt other forms, and is not limited to the forms mentioned in the above embodiments, as long as it can achieve the function of detecting abnormal conditions in the AC circuit to be tested.

[0076] Based on the same inventive concept, the present application also provides a non-contact AC circuit voltage detection method, which is applied to the non-contact AC circuit voltage detection device provided in any of the above embodiments; the device includes an electromagnetic induction clamp 11, a signal conditioning module 12, a signal processing module 13 and an audible and visual alarm module 14;

[0077] The method includes: detecting the AC voltage of the AC circuit to be tested by an electromagnetic induction clamp 11, generating an electric potential corresponding to the AC circuit to be tested when the AC voltage is detected, transmitting the electric potential to a signal conditioning module 12 for amplification, and then transmitting it to an electrically connected signal processing module 13; driving the signal processing module 13 to compare the received electric potential with a preset electromotive force threshold, and when the comparison result indicates that the electric potential is greater than the preset electromotive force threshold, determining that an abnormality exists in the AC circuit to be tested, transmitting an alarm signal to the sound and light alarm module 14, and driving the sound and light alarm module 14 to issue an abnormality alarm.

[0078] Specifically, the non-contact AC circuit voltage detection device provided by the present application is also a non-contact AC parasitic circuit detection device, and its working principle diagram can be shown as follows: Figure 5 As shown in the figure, when the motor power supply (AC) and control power supply (AC) air switches of a device to be detected are in the disconnected state, the normally closed auxiliary contacts of the air switch are closed, so that the power supply of the non-contact AC parasitic circuit detection device is connected and the device starts working. The device detects the AC voltage of the AC secondary circuit to be detected through an electromagnetic induction clamp. If the AC voltage is detected, the electromagnetic induction clamp will induce a small induced electromotive force. The electromotive force is amplified by the signal conditioning module, and the signal processing module compares the amplified electromotive force with the nominal electric field measurement value. If the potential value exceeds the threshold, it indicates that the detected circuit is abnormally energized, and there may be an electrical fault or a parasitic circuit. At this time, the signal processing module triggers the sound and light alarm module and outputs an sound and light signal to remind the operator to take emergency safety measures. At the same time, it will drive the alarm signal output relay to operate, so that the alarm signal is transmitted to the corresponding measurement and control device, prompting the operator that the device has a parasitic circuit.

[0079] in, Figure 5 The load in the transformer substation refers to the motors of some isolating switches, grounding switches, and AC relays of the control circuits. NL is the live wire, the live wire is marked with L (Live Wire), and the neutral wire is marked with N (Neutralwire). Figure 5 51 in the figure can be an air switch.

[0080] It can be seen that this application has developed a non-contact AC parasitic circuit detection device based on the principle of electromagnetic induction. The detection device can meet the requirements of accurate, efficient and reliable real-time detection and alarm of AC parasitic circuits. By designing a highly sensitive electromagnetic induction wire clamp and a low-noise amplifier circuit, it successfully realizes the accurate detection of abnormal AC voltage in a non-contact state, and exhibits excellent anti-interference performance in a complex electromagnetic environment. Finally, the practicality and safety of the detection device are effectively improved through the sound and light alarm module. The device can accurately detect AC parasitic circuits in a non-contact manner and improve the overall detection capability of the system.

[0081] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0082] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A non-contact AC circuit voltage detection device, characterized in that: It includes an electromagnetic induction clamp, a signal conditioning module, a signal processing module and an audible and visual alarm module; The electromagnetic induction clamp is non-contactly located within a preset range of the AC circuit to be tested and is electrically connected to the signal conditioning module, and is used to transmit the sensed potential corresponding to the AC circuit to be tested to the signal conditioning module; The signal conditioning module is used to amplify the received electric potential and transmit the amplified electric potential to the electrically connected signal processing module; wherein the signal conditioning module comprises a first-stage amplifier and a second-stage amplifier electrically connected through a first capacitor, a signal input end of the first-stage amplifier is electrically connected to the electromagnetic induction clamp, a signal output end of the second-stage amplifier is electrically connected to the signal processing module, and the signal conditioning module further comprises a current source electrically connected to the first-stage amplifier; The signal processing module is used to compare the received electric potential with a preset electromotive force threshold value. When the comparison result indicates that the electric potential is greater than the preset electromotive force threshold value, it is determined that there is an abnormality in the AC circuit to be tested, and an alarm signal is transmitted to the sound and light alarm module to drive the sound and light alarm module to issue an abnormality alarm.

2. The non-contact AC circuit voltage detection device according to claim 1, characterized in that: The first stage amplifier includes a first transistor, a second transistor, a first resistor, a second resistor, a third resistor, a fourth resistor and a first amplifier; The control electrode of the first transistor is electrically connected to the electromagnetic induction clamp, the first electrode of the first transistor is electrically connected to the first electrode of the second transistor, and the second electrode of the first transistor is electrically connected to the first end of the first resistor and the first input end of the first amplifier; The second electrode of the second transistor is electrically connected to the first electrode of the second resistor and the second input terminal of the first amplifier, and the control electrode of the second transistor is electrically connected to the first end of the third resistor and the first end of the fourth resistor; The second end of the first resistor and the second end of the second resistor are electrically connected to the first power supply end; The second end of the third resistor and the output end of the first amplifier are electrically connected to the first plate of the first capacitor; A second end of the fourth resistor is grounded.

3. The non-contact AC circuit voltage detection device according to claim 2, characterized in that: The second stage amplifier includes a second amplifier, a second capacitor, a fifth resistor, a sixth resistor and a seventh resistor; A first end of the fifth resistor is electrically connected to the second plate of the first capacitor, and a second end of the fifth resistor is electrically connected to the first input end of the second amplifier; After the sixth resistor and the second capacitor are connected in parallel, they are electrically connected to the first input end of the second amplifier and the output end of the second amplifier; The output end of the second amplifier is electrically connected to the signal processing module through the seventh resistor, and the second input end of the second amplifier is grounded.

4. The non-contact AC circuit voltage detection device according to claim 3, characterized in that: The current source includes a third transistor, a fourth transistor, an eighth resistor, a ninth resistor and a tenth resistor; The first electrode of the third transistor is electrically connected to the first power supply terminal through the eighth resistor, and the first electrode is electrically connected to the control electrode of the third transistor and the control electrode of the fourth transistor; the second electrode of the third transistor is electrically connected to the second power supply terminal through the ninth resistor; A first electrode of the fourth transistor is electrically connected to a first electrode of the first transistor, and a second electrode of the fourth transistor is electrically connected to the second power supply terminal through the tenth resistor.

5. The non-contact AC circuit voltage detection device according to claim 2, characterized in that: At least one of the first transistor and the second transistor is a junction field effect transistor.

6. The non-contact AC circuit voltage detection device according to claim 4, characterized in that: The third transistor and the fourth transistor are triodes of the same specification; The calculation formula of the current value of the current source is: ; Wherein, R8 is the resistance value of the ninth resistor, R9 is the resistance value of the ninth resistor, R 10 is the resistance value of the tenth resistor, V DD is the input voltage value of the first power supply terminal, V SS is the input voltage value of the second power supply terminal, U BEO is the voltage value between the control electrode and the first electrode of the third transistor.

7. The non-contact AC circuit voltage detection device according to claim 6, characterized in that: The calculation formula of the source-drain current value of the first transistor is: .

8. The non-contact AC circuit voltage detection device according to claim 1, characterized in that: Also includes a power module; The power supply module is electrically connected to the signal conditioning module, the signal processing module and the sound and light alarm module respectively.

9. The non-contact AC circuit voltage detection device according to claim 1, characterized in that: The sound and light alarm module includes a piezoelectric buzzer, an LED indicator light and an alarm signal output relay; the alarm signal output relay closes contacts based on the alarm signal and transmits the alarm signal to the data storage module for storage.

10. A non-contact AC circuit voltage detection method, characterized in that: A non-contact AC circuit voltage detection device as described in any one of claims 1 to 9; the device comprises an electromagnetic induction clamp, a signal conditioning module, a signal processing module and an audible and visual alarm module; The method comprises: The AC voltage of the AC circuit to be tested is detected by the electromagnetic induction clamp. When the AC voltage is detected, an electric potential corresponding to the AC circuit to be tested is generated, and the electric potential is transmitted to the signal conditioning module for amplification, and then transmitted to the electrically connected signal processing module; the signal processing module is driven to compare the received electric potential with a preset electromotive force threshold value. When the comparison result indicates that the electric potential is greater than the preset electromotive force threshold value, it is determined that the AC circuit to be tested is abnormal, and an alarm signal is transmitted to the sound and light alarm module, driving the sound and light alarm module to alarm for abnormality.

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