A pulse current partial discharge sensor

Abstract

This utility model discloses a pulse current partial discharge sensor. The sensor housing consists of a shell and a cover that snap together to form a receiving cavity. The shell or cover surface has magnetic attraction for easy installation. A control unit, containing the partial discharge sensor, is installed within the receiving cavity. A grounding post penetrates the shell and is electrically connected to the control unit. A resistance detector is also placed within the receiving cavity, with its detection contacts electrically connected to the grounding post. This allows for real-time acquisition of grounding resistance values, replacing traditional manual multimeter testing, avoiding missed detections, and the elastic conductive contacts can adapt to the vibration environment of switchgear, ensuring mechanical stability. An alarm unit is electrically connected to the resistance detector; when the resistance detector detects that the grounding post is not grounded, an alarm is triggered. This sensor controls grounding quality from the source, reducing the sensor failure and repair rate caused by poor grounding.

Description

Technical Field

[0001] This utility model relates to the field of power equipment condition monitoring technology, and in particular to a pulse current partial discharge sensor. Background Technology

[0002] The pulse current method is currently the mainstream technology for testing partial discharge in electrical equipment. It quantitatively assesses the insulation status of equipment by measuring the apparent discharge quantity (unit: pC). In existing technologies, pulse current partial discharge sensors typically employ a magnetic mounting structure, relying on manual operation to achieve grounding connection. However, in actual installation, the following technical drawbacks exist:

[0003] 1. Grounding status relies on manual confirmation: When the magnetic surface at the bottom of the sensor contacts the cabinet, if there is an insulating coating on the surface of the cabinet, it will cause the grounding resistance to be too high or even not grounded. However, the existing technology lacks automatic detection methods and relies entirely on the visual inspection of the installer or the detection of a multimeter, which is inefficient and prone to missed detection due to operational negligence.

[0004] 2. Hidden faults are difficult to detect: Poor grounding can cause sensor measurement reference to shift, leading to misjudgment or missed detection of partial discharge signals. Long-term operation may cause equipment insulation deterioration that is not detected in time. Utility Model Content

[0005] The purpose of this invention is to disclose a pulse current partial discharge sensor that integrates a resistance detector and an alarm unit to achieve real-time automatic detection and alarm of grounding status, thereby fundamentally solving the problems of measurement errors and equipment damage caused by poor grounding.

[0006] To achieve the above objectives, this utility model discloses a pulse current partial discharge sensor, comprising: a sensor housing, the sensor housing including a shell and a cover that are snapped together, a receiving cavity formed between the shell and the cover, and a magnetic attraction fixed to the surface of the shell or the cover; a control unit, the control unit being assembled in the receiving cavity, the control unit including the partial discharge sensor; a grounding post, the grounding post passing through the shell, the cover and the control unit, and electrically connected to the control unit; a resistance detector, the resistance detector being assembled in the receiving cavity, the resistance detector having a detection contact, the detection contact being electrically connected to the grounding post; and an alarm unit, the alarm unit being electrically connected to the resistance detector, used to trigger when the resistance detector detects that the grounding post is not grounded.

[0007] By adopting the above scheme, the resistance detector contacts the side wall of the grounding post through conductive detection contacts, and collects the grounding resistance value in real time. Real-time monitoring of grounding resistance by the resistance detector replaces traditional manual multimeter testing, avoiding missed detections due to operational negligence. The flexible conductive contacts ensure mechanical stability and adapt to the vibration environment of the switchgear. By controlling grounding quality at the source, the return rate of sensor failures due to poor grounding is reduced.

[0008] Further, the resistance detector includes: a housing, which is mounted on the control unit, with the detection contact extending out of the housing; a voltage divider unit, disposed within the housing, with one end electrically connected to the control unit and the other end electrically connected to the detection contact; a filtering unit, disposed within the housing, connected in parallel between the detection contact and the control unit; a threshold comparison unit, disposed within the housing, with its input terminal connected to both the detection contact and a preset threshold circuit, for determining the resistance state of the grounding post; and an output unit, electrically connected to the output terminal of the threshold comparison unit, for providing a trigger signal to the alarm unit.

[0009] By adopting the above scheme, key components such as the voltage divider unit, filtering unit, threshold comparison unit, and output unit are all integrated into the housing, which is mounted on the control unit. This integrated design makes the entire resistance detector compact, space-saving, and easy to install and layout in various devices or systems. One end of the voltage divider unit is electrically connected to the control unit, and the other end is electrically connected to the detection contact. It divides the voltage signal obtained by the detection contact according to a certain ratio, adapting it to the input voltage range of the control unit, avoiding damage to the control unit or affecting measurement accuracy due to excessively high or low voltage. The filtering unit is connected in parallel between the detection contact and the control unit, filtering out high-frequency noise and interference signals in the detection signal, making the signal transmitted to the control unit purer and more stable, thereby improving the accuracy and reliability of resistance detection. The input terminals of the threshold comparison unit are connected to the detection contact and the preset threshold circuit respectively. It compares the detected grounding post resistance signal with the preset threshold and automatically determines the resistance state of the grounding post based on the comparison result, such as whether it is normal, short-circuited, or open-circuited, realizing intelligent detection of resistance state. The output unit is electrically connected to the output terminal of the threshold comparison unit. When the threshold comparison unit determines that the grounding post resistance is abnormal, the output unit can quickly provide a trigger signal to the alarm unit, so that the alarm unit can issue an alarm in time, reminding relevant personnel to take measures to ensure the safe operation of the equipment and system.

[0010] Furthermore, the detection contact is an elastic conductive contact, including a detection element and an elastic element, wherein the detection element abuts against the side wall of the grounding post.

[0011] By employing the above scheme, the elastic element provides continuous and stable elastic force to the sensing element, ensuring a tight fit between the sensing element and the sidewall of the grounding post. This continuous pressure ensures a good electrical connection between the sensing contact and the grounding post under various operating conditions, reducing contact resistance and thus improving the accuracy of resistance detection. The sidewall of the grounding post may have uneven surfaces, oxide layers, or dirt. The elastic properties of the flexible conductive contact allow the sensing element to adapt to the surface condition of the grounding post to a certain extent, filling in minor surface irregularities through elastic deformation, ensuring an effective contact area with the grounding post, and reducing measurement errors caused by poor contact.

[0012] Furthermore, the control unit includes a power supply, the power supply outputting a voltage of 3.3V or 5V, for simultaneously powering the resistance detector and the control unit.

[0013] By adopting the above solution, which provides both 3.3V and 5V voltages, a more stable operating voltage can be provided for different circuit modules.

[0014] Furthermore, the resistor detector is electrically connected to the control unit via an optocoupler isolation circuit.

[0015] By adopting the above solution, we can address the various electromagnetic interference sources present in industrial environments or complex electronic systems, such as motors, transformers, and high-frequency equipment. These interferences may couple into the signal transmission lines between the resistor detector and the control unit via wires, affecting the accuracy and stability of the signal. Optical isolation circuits offer excellent electromagnetic isolation performance, effectively blocking external electromagnetic interference and ensuring pure signal transmission.

[0016] Furthermore, the threshold comparison unit employs an LM393 voltage comparator.

[0017] By adopting the above solution, the LM393 has an extremely short response time, enabling it to quickly capture voltage changes and output corresponding signals. In scenarios requiring real-time monitoring, such as overvoltage protection for industrial equipment, it can respond promptly to voltage surges, quickly triggering protection mechanisms to prevent equipment damage.

[0018] Furthermore, the control unit is provided with a first PCB board, and the housing is provided with a second PCB board facing the first PCB board. The second PCB board is used to integrate a voltage divider unit, a filter unit, a threshold comparison unit, and an output unit. The first PCB board and the second PCB board are electrically connected through a board-to-board connector.

[0019] By adopting the above solution, two PCB boards are used to carry different functional modules, making the structure of the entire control unit more modular.

[0020] Furthermore, the alarm unit is a buzzer, which is mounted on the housing and electrically connected to the second PCB board.

[0021] By adopting the above scheme, the buzzer can emit a loud and penetrating sound. When the threshold comparison unit on the second PCB board detects an abnormal signal, such as the resistance value detected by the resistance detector exceeding the safe range, it will quickly send an electrical signal to the buzzer, causing it to immediately sound an alarm.

[0022] Furthermore, the first PCB board is provided with multiple mounting holes for assembly and connection with the housing.

[0023] By adopting the above solution, the outer shell can be adjusted and assembled, and the multiple mounting holes act as multiple fixing points, which can firmly fix the first PCB board to the outer shell.

[0024] Furthermore, the outer casing is made of an insulating material.

[0025] By adopting the above solution, electronic devices generate electromagnetic fields during operation and are also subject to interference from external electromagnetic fields. Insulating materials typically possess electromagnetic shielding properties, which can reduce the impact of external electromagnetic interference on the internal signal transmission of the device, while also preventing internal electromagnetic radiation from leaking to the outside and avoiding interference with other electronic devices.

[0026] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. By integrating a resistance detector and detection contacts, the sensor can acquire the resistance value of the grounding post in real time, replacing traditional manual visual inspection or multimeter testing methods. The detection contacts of the resistance detector make elastic contact with the side wall of the grounding post, ensuring mechanical stability and adapting to the vibration environment of the switchgear. This design fundamentally solves the problems of low efficiency and easy omissions in manual testing, avoiding excessive grounding resistance or even failure to ground due to the insulating coating on the cabinet surface or operational negligence. 2. Poor grounding can cause sensor measurement reference to shift, leading to misjudgment or missed detection of partial discharge signals. This sensor ensures that measurement data is always based on a stable grounding state by monitoring the grounding resistance in real time, controlling measurement errors at the source. In long-term operation, it can effectively prevent equipment insulation degradation caused by grounding problems from going undetected, reducing equipment failure rates. 3. When the resistance detector detects that the grounding post is not grounded, the alarm unit, such as a buzzer, is immediately triggered, forming a "detection-judgment-alarm" closed loop. This instant feedback mechanism enables maintenance personnel to locate problems immediately, avoiding sensor failures or equipment damage caused by poor grounding, and significantly improving the safety and reliability of the power system; 4. Automated detection and alarm functions reduce unplanned downtime and the frequency of manual inspections, while also lowering the return rate of sensor failures due to poor grounding. Real-world application examples show that after adopting this technology, a substation experienced improved operation and maintenance efficiency and a significant reduction in fault response time. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a three-dimensional structural diagram of an embodiment of the present utility model.

[0029] Figure 2 This is a partial exploded structural diagram of an embodiment of the present invention.

[0030] Figure 3 This is a partial exploded structural diagram of an embodiment of the present invention.

[0031] Figure 4 for Figure 2 Enlarged view of area A in the middle.

[0032] Figure 5 This is a schematic diagram of a partial module connection structure according to an embodiment of the present utility model.

[0033] Key reference numerals in the attached drawings: 1. Sensor housing; 11. Housing; 12. Cover; 13. Receiving cavity; 14. Magnetic attraction; 15. Grounding post; 2. Control unit; 3. Resistance detector; 31. Housing; 32. Voltage divider unit; 33. Filtering unit; 34. Threshold comparison unit; 341. Preset threshold circuit; 35. Output unit; 36. Detection contact; 361. Detection element; 362. Elastic element; 4. Alarm unit; 5. First PCB board; 6. Second PCB board; 7. Power supply. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0035] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0036] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0037] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0038] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0039] The technical solution of this utility model will be further described below with reference to the embodiments and accompanying drawings.

[0040] Please refer to Embodiment 1 of this utility model. Figures 1 to 5 As shown, a pulse current partial discharge sensor is provided, including a sensor housing 1, a control unit 2, a grounding post 15, a resistance detector 3, and an alarm unit 4. The sensor housing 1 consists of a shell 11 and a cover 12 that are snapped together, forming a receiving cavity 13 to accommodate other key components. This sensor, by integrating the resistance detector 3 and the alarm unit 4, achieves real-time automatic detection of the grounding status and provides alarms for abnormalities, effectively solving the measurement errors and equipment damage problems caused by poor grounding in existing technologies.

[0041] In this embodiment 1, the housing 11 and cover 12 of the sensor housing 1 are made of high-strength insulating engineering plastic, such as PC or ABS. This material not only has good insulation performance, which can effectively reduce the impact of external electromagnetic interference on the signal transmission inside the device, but also prevents the electromagnetic radiation inside the device from leaking to the outside, avoiding interference with other electronic devices; it also has high mechanical strength, which can withstand certain external impacts and vibrations, protecting the internal components from damage.

[0042] The housing 11 and the cover 12 are connected by a snap-fit ​​structure or bolts. The snaps are evenly distributed on the edges of the housing 11 and the cover 12 to ensure a tight and secure connection. A magnet 14 is fixed to the surface of the housing 11 or the cover 12. The magnet 14 is made of a strong magnetic material, such as a neodymium iron boron magnet, which has a strong attraction force and can firmly attach the sensor to metal cabinets such as switch cabinets, facilitating installation and removal.

[0043] The control unit 2 is assembled within the receiving cavity 13 of the sensor housing 1, and its core component is the first PCB board 5. The first PCB board 5 adopts a multi-layer printed circuit board design, which has good electrical and heat dissipation performance. The board is provided with multiple mounting holes for assembly and connection with the housing 31. These mounting holes are evenly distributed along the edge of the first PCB board 5, and the first PCB board 5 is firmly fixed to the housing 31 with screws to ensure that it will not loosen due to vibration during equipment operation.

[0044] The control unit 2 includes a power supply 7, which outputs either 3.3V or 5V, capable of simultaneously powering both the resistance detector 3 and the control unit 2 itself. This dual-voltage output design provides a more stable operating voltage for different circuit modules, meeting the power supply requirements of various components. The power supply 7 utilizes a high-efficiency switching power supply module, offering advantages such as small size, high efficiency, and good stability.

[0045] Control unit 2 also includes a partial discharge sensor for measuring the apparent discharge of electrical equipment. Its measurement accuracy is ±1 pC, enabling accurate assessment of the equipment's insulation status. The partial discharge sensor is connected to a signal processing circuit on the first PCB board. The signal processing circuit amplifies and filters the signal collected by the partial discharge sensor, then transmits the processed signal to subsequent circuits for analysis and judgment. The partial discharge sensor is existing technology and will not be described in detail here.

[0046] The grounding post 15 penetrates the housing 11, cover 12, and control unit 2 of the sensor housing 1, and is made of a highly conductive metal material, such as copper alloy. One end of the grounding post 15 is electrically connected to the control unit 2, and the other end extends to the outside of the sensor housing 1 for grounding to a metal cabinet such as a switch cabinet. The grounding post 15 is isolated from the housing 11 and cover 12 by an insulating sleeve to ensure good insulation between the grounding post 15 and the housing and to prevent short circuit faults.

[0047] The resistance detector 3 is mounted on the first PCB board 5 of the control unit 2. A second PCB board 6 is disposed on its housing 31 facing the first PCB board 5. The second PCB board 6 integrates a voltage divider unit 32, a filter unit 33, a threshold comparison unit 34, and an output unit 35. The first PCB board 5 and the second PCB board 6 are electrically connected via a board-to-board connector. This connection method has advantages such as reliable connection and stable signal transmission.

[0048] The outer casing 31 of the resistance detector 3 is made of the same insulating engineering plastic as the sensor housing 1, possessing good insulation performance and mechanical strength. The housing 31 is mounted on the first PCB board 5 of the control unit 2 and secured with screws to ensure a firm installation. The housing 31 is provided with a detection contact 36 protrusion hole, through which the detection contact 36 protrudes from the housing 31 and is electrically connected to the grounding post 15.

[0049] Preferably, the detection contact 36 is a resilient conductive contact, comprising a detection element 361 and a resilient element 362. The detection element 361 is made of a highly conductive metal material, such as copper, and its surface is gold-plated to improve conductivity and oxidation resistance. The resilient element 362 is made of spring steel, possessing good elasticity and durability. The elastic coefficient of the resilient element 362 is k = 0.5 N / mm ± 10%, and the initial contact pressure is ≥ 1 N. For example, the contact pressure generated by the resilient element 362 when it abuts against the side wall of the grounding post 15 is ≥ 1 N. The resilient element 362 provides continuous and stable elastic force to the detection element 361, ensuring that the detection element 361 is tightly abutted against the side wall of the grounding post 15. This resilient contact method ensures a good electrical connection between the detection contact 36 and the grounding post 15 under various operating conditions, reducing contact resistance and thus improving the accuracy of resistance detection. Meanwhile, the elastic properties of the elastic conductive contact enable the detection element 361 to adapt to the surface condition of the grounding post 15 to a certain extent, fill the small unevenness of the surface through elastic deformation, ensure the effective contact area with the grounding post 15, and reduce the measurement error caused by poor contact.

[0050] The voltage divider unit 32 is located inside the outer casing 31 of the resistance detector 3. One end of it is electrically connected to the first PCB board of the control unit 2, and the other end is electrically connected to the detection contact 36. The voltage divider unit 32 adopts a resistor voltage divider circuit, which consists of two high-precision resistors with a resistance accuracy of ±0.1%. The resistor voltage divider circuit is a conventional circuit, and specific connection details are not provided here. By appropriately selecting the resistor values, the voltage divider unit 32 can divide the voltage signal obtained by the detection contact 36 according to a certain ratio, making it compatible with the input voltage range of the control unit 2, thus avoiding damage to the control unit 2 or affecting the measurement accuracy due to excessively high or low voltage.

[0051] The filter unit 33 is located inside the housing 31 of the resistance detector 3 and connected in parallel between the detection contact 36 and the control unit 2. The filter unit 33 employs an RC filter circuit, composed of resistors and capacitors. The RC filter circuit achieves a common-mode rejection ratio (CMRR) ≥60dB and an attenuation slope ≥-40dB / dec in the 10MHz-100MHz frequency band. The test conditions for CMRR ≥60dB are: signal source output impedance 50Ω, load impedance 1MΩ, and a network analyzer. The RC filter circuit is a conventional circuit structure and is not specifically limited here. The filter circuit can filter out high-frequency noise and interference signals in the detection signal, making the signal transmitted to the control unit 2 purer and more stable, thereby improving the accuracy and reliability of the resistance detection. The parameters of the resistors and capacitors are selected according to actual needs to ensure that the filtering effect meets the requirements.

[0052] The threshold comparison unit 34 is located inside the outer casing 31 of the resistance detector 3 and uses an LM393 voltage comparator. The LM393 features an extremely short response time, enabling it to quickly capture voltage changes and output corresponding signals. Its inputs are connected to the detection contact 36 and the preset threshold circuit 341, respectively. The preset threshold circuit 341 sets different thresholds through resistor voltage division to determine the resistance state of the grounding post 15. When the detected resistance signal of the grounding post 15 is greater than or less than the preset threshold, the LM393 outputs a corresponding level signal, achieving intelligent detection of the resistance state.

[0053] The output unit 35 is electrically connected to the output terminal of the threshold comparison unit 34. Preferably, an optocoupler isolation circuit can be used. In other embodiments, other circuits can be used as long as they achieve the desired anti-interference effect. The optocoupler isolation circuit has good electromagnetic isolation performance, which can effectively block the intrusion of external electromagnetic interference and ensure the pure transmission of signals. In industrial environments or complex electronic systems, there are various sources of electromagnetic interference, such as motors, transformers, and high-frequency equipment. These interferences may couple into the signal transmission line between the resistance detector 3 and the control unit 2 through wires, affecting the accuracy and stability of the signal. The optocoupler isolation circuit can electrically isolate the input and output signals to avoid the influence of interference signals. When the threshold comparison unit 34 determines that the resistance state of the grounding post 15 is abnormal, the output unit 35 provides a trigger signal to the alarm unit 4 through the optocoupler isolation circuit.

[0054] Alarm unit 4 consists of a buzzer mounted on the outer casing 31 of the resistance detector 3 and electrically connected to the second PCB board. The buzzer is a piezoelectric buzzer, which has advantages such as small size, loud sound, and low power consumption. When the threshold comparison unit 34 on the second PCB board detects an abnormal signal, such as the resistance value detected by the resistance detector 3 exceeding the safe range, it will quickly send an electrical signal to the buzzer, causing it to immediately sound an alarm. The buzzer's sound frequency is 2kHz-4kHz, and the volume can reach over 85dB, producing a loud and penetrating sound to alert maintenance personnel to take timely measures.

[0055] When the pulse current partial discharge sensor is magnetically attached to a metal cabinet such as a switchgear by magnetic attraction 14, the grounding post 15 is grounded to the cabinet. The detection contact 36 of the resistance detector 3 makes elastic contact with the side wall of the grounding post 15, acquiring the resistance value of the grounding post 15 in real time. The voltage divider unit 32 divides the voltage signal acquired by the detection contact 36, and the filter unit 33 filters out high-frequency noise and interference signals in the signal, and then transmits the processed signal to the threshold comparison unit 34. The threshold comparison unit 34 compares the detected resistance signal with a preset threshold to determine the resistance status of the grounding post 15. If the grounding post 15 is not grounded or the grounding resistance is too high, the threshold comparison unit 34 outputs an abnormal signal, which triggers the alarm unit 4 through the output unit 35 and the optocoupler isolation circuit. The buzzer sounds an alarm to remind maintenance personnel to deal with the grounding problem in time. At the same time, the partial discharge sensor in the control unit 2 normally measures the apparent discharge of the electrical equipment, providing accurate data for the equipment insulation status assessment.

[0056] Specifically, in this embodiment 1, the preset threshold circuit 341 only requires two resistors R2 and R3 and one capacitor C2. The voltage divider resistors R2 and R3 are connected in series between the low-voltage power supply 7 of the sensor control unit 2 and the connecting post, that is, between VCC and GND. Vth = VCC × [R3 / (R2 + R3)]. When VCC = 5V, and R2 = 4kΩ and R3 = 1kΩ are selected, Vth = 5V × (1kΩ / (4kΩ + 1kΩ)) = 1V. This threshold is suitable for grounding detection requirements. The circuit structure of the voltage divider detection unit consists of a reference resistor R1 and a detection resistor R grounded. The power supply voltage VCC is connected to the detection terminal through R1. Under normal grounding: R ground ≤ 100Ω. Taking VCC = 5V as an example, the voltage at the voltage divider point (TEST) ≈ (R ground / (R1 + R ground)) × VCC ≈ 0.05V. When not grounded / malfunctioning: R ground ≥ 1MΩ, voltage divider point (TEST) ≈ (1M / (10k + 1M))×VCC ≈ 4.95V (close to VCC). When TEST voltage < Vth (normal grounding): comparator output low level (0V). When TEST voltage ≥ Vth (not grounded / malfunctioning): comparator output high level (VCC). When the comparator outputs high level, the buzzer sounds, and the duration can be selected from 3-5s according to the actual situation. To achieve graded alarm, two-stage LM393 comparators can be set. The first stage threshold corresponds to 100Ω (Vth1=0.5V), and the second stage threshold corresponds to 1kΩ (Vth2=2.5V), and the buzzer output mode is either a continuous sound or an intermittent short sound.

[0057] It should be noted that the voltage divider resistors R2 and R3 must be metal film resistors with an accuracy of ±1% and a temperature coefficient of ±50ppm. Their resistance ranges must meet the following requirements: R2 = 3kΩ-5kΩ, R3 = 0.8kΩ-1.2kΩ, ensuring Vth = 0.8V-1.2V. They must also pass a temperature drift test from 20℃ to 80℃, with a threshold drift rate <±0.1V. After temperature and humidity cycling tests (-40℃~85℃ / 95%RH, 48h) and vibration tests (10Hz-500Hz / 5Grms), the threshold drift rate must still remain <±0.1V. The RC filter circuit must be designed with a cutoff frequency fc = 1MHz (-3dB), resistor R = 1kΩ ±5%, capacitor C = 160pF ​​±10%, and NPO material.

[0058] The technical means disclosed in this utility model are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications are also considered within the scope of protection of this utility model.

Claims

1. A pulsed current partial discharge sensor characterized by, include: The sensor housing (1) includes a shell (11) and a cover (12) that are fastened together. A receiving cavity (13) is formed between the shell (11) and the cover (12). A magnetic attraction (14) is fixed on the surface of the shell (11) or the cover (12). Control unit (2), which is assembled in the receiving cavity (13), includes a partial discharge sensor; A grounding post (15) passes through the housing (11), the cover (12) and the control unit (2), and is electrically connected to the control unit (2); A resistance detector (3) is assembled in the receiving cavity (13), and the resistance detector (3) has a detection contact (36) which is electrically connected to the grounding post (15). An alarm unit (4) is electrically connected to the resistor detector (3) and is used to trigger the alarm when the resistor detector (3) identifies that the grounding post (15) is not grounded.

2. A pulsed current PD sensor according to claim 1, characterised in that, The resistance detector (3) includes: The outer casing (31) is mounted on the control unit (2), and the detection contact (36) extends out of the outer casing (31); The voltage divider unit (32) is located inside the housing (31). One end of the voltage divider unit (32) is electrically connected to the control unit (2), and the other end is electrically connected to the detection contact (36). A filter unit (33) is disposed inside the outer casing (31) and is connected in parallel between the detection contact (36) and the control unit (2). A threshold comparison unit (34) is located inside the outer casing (31). The input terminals of the threshold comparison unit (34) are connected to the detection contact (36) and the preset threshold circuit (341) respectively, and are used to determine the resistance state of the grounding post (15). The output unit (35) is electrically connected to the output terminal of the threshold comparison unit (34) and is used to provide a trigger signal to the alarm unit (4).

3. A pulsed current PD sensor according to claim 2, wherein, The detection contact (36) is an elastic conductive contact, including a detection element (361) and an elastic element (362), wherein the detection element (361) abuts against the side wall of the grounding post (15).

4. A pulsed current PD sensor according to claim 1, wherein The control unit (2) includes a power supply (7), which outputs a voltage of 3.3V or 5V to simultaneously power the resistor detector (3) and the control unit (2).

5. A pulse current partial discharge sensor according to claim 1, characterized in that, The resistor detector (3) is electrically connected to the control unit (2) through an optocoupler isolation circuit.

6. A pulse current partial discharge sensor according to claim 2, characterized in that, The threshold comparison unit (34) uses an LM393 voltage comparator.

7. A pulse current partial discharge sensor according to claim 2, characterized in that, The control unit (2) is provided with a first PCB board (5), and the outer shell (31) is provided with a second PCB board (6) facing the first PCB board (5). The second PCB board (6) is used to integrate a voltage divider unit (32), a filter unit (33), a threshold comparison unit (34), and an output unit (35). The first PCB board (5) and the second PCB board (6) are electrically connected through a board-to-board connector.

8. A pulse current partial discharge sensor according to claim 7, characterized in that, The alarm unit (4) is a buzzer, which is mounted on the outer casing (31) and electrically connected to the second PCB (6) board.

9. A pulse current partial discharge sensor according to claim 7, characterized in that, The first PCB board (5) is provided with a plurality of mounting holes for assembly and connection with the outer casing (31).

10. A pulse current partial discharge sensor according to claim 2, characterized in that, The outer shell (31) is made of insulating material.

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