Partial discharge detector for cable

Abstract

The invention discloses a partial discharge detector for a cable, relates to the technical field of electrical engineering, and realizes accurate anti-interference acquisition and on-line self-calibration of sensing signals in cable partial discharge detection by virtue of the synergistic effect of a rotary electromagnetic shielding cover assembly and a mechanical pulse calibration assembly. Different from a traditional lagging low-efficiency scheme depending on electronic filtering and external calibration, partial discharge detection is more accurate and reliable, firstly, a rotary electromagnetic shielding cover assembly is utilized, through the mechanical design of synchronous opening and closing of a first shielding cover, a second shielding cover and a phase, asynchronous electromagnetic noise can be physically isolated through mechanical rotation, and partial discharge detection is more accurate and reliable; the problem of signal distortion of traditional electronic filtering is thoroughly solved, power frequency voltage phases can be dynamically adapted, synchronous discharge pulses can be accurately captured, and the measurement distortion risk and the discharge capacity estimation deviation of weak discharge signals are greatly reduced. The bottleneck that a traditional electronic calibration device is interfered by the environment is broken through.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering technology, specifically to a partial discharge detector for cables. Background Technology

[0002] A partial discharge detector for cables is a specialized electrical device used to detect partial discharge phenomena in cable insulation systems. It captures weak discharge signals generated by concentrated electric fields inside the cable insulation, analyzes the intensity, frequency, phase, and other characteristics of the discharge, and thus determines the aging degree and potential defects of the cable insulation. This provides core information for cable factory acceptance, installation and commissioning, operation and maintenance, and fault early warning.

[0003] Existing partial discharge detectors for cables, such as high-frequency current transformers (HFCTs) for partial discharge detection, rely on the sensor's electromagnetic induction signal reception and the back-end algorithm's digital filtering processing. After signal amplification, digital-to-analog conversion, and software analysis, the discharge signal is identified and quantified. This purely electronic signal processing stage has inherent background noise and is susceptible to environmental electromagnetic interference, making it difficult to accurately match the sensor's actual output signal with the real discharge pulse. In complex field testing, phenomena such as the drowning of effective signals, misjudgment of pulse polarity, and inaccurate estimation of discharge quantity often occur. Furthermore, the use of electronic filtering methods for noise reduction has inherent contradictions, and the algorithm's filtering characteristics are prone to signal distortion. It cannot adaptively match the nonlinear electromagnetic response changes caused by the diversity of field interference sources, differences in cable laying, and types of insulation defects. It is difficult to extract effective signals when dealing with strong corona interference, inaccurate pulse source identification when distinguishing noise from nearby equipment, and missed detection in the early stages of weak discharge due to insufficient signal-to-noise ratio. This leads to problems such as decreased detection reliability, misjudgment of defect types, and distortion of equipment condition assessment conclusions.

[0004] Therefore, we propose a partial discharge detector for cables to solve the problems mentioned above. Summary of the Invention

[0005] The purpose of this invention is to provide a partial discharge detector for cables. By leveraging the synergistic effect of a rotary electromagnetic shielding assembly and a mechanical pulse calibration assembly, it achieves accurate anti-interference acquisition and online self-calibration of sensor signals in partial discharge detection of cables. This is different from the traditional lag-prone and inefficient solutions that rely on electronic filtering and external calibration, making partial discharge detection more accurate and reliable.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a partial discharge detector for cables, comprising a housing, a rotary electromagnetic shielding assembly, and a mechanical pulse calibration assembly, wherein the rotary electromagnetic shielding assembly and the mechanical pulse calibration assembly are respectively installed inside the housing, and the rotary electromagnetic shielding assembly is provided on one side of the outer wall of the mechanical pulse calibration assembly;

[0007] The rotary electromagnetic shielding cover assembly includes a first shielding cover, a second shielding cover, two fan-shaped windows, and four thick beryllium copper springs. The first shielding cover is used to achieve preliminary isolation of broad-spectrum and indiscriminate electromagnetic interference. The second shielding cover is used to physically isolate asynchronous noise. The two fan-shaped windows are symmetrically arranged and are used to isolate asynchronous electromagnetic noise. The four thick beryllium copper springs are used to fill the rotation gap between the first shielding cover and the second shielding cover.

[0008] The mechanical pulse calibration assembly includes a piezoelectric ceramic actuator, a striker, and a ceramic capacitor. The piezoelectric ceramic actuator is used to convert electrical signal commands into precise and controllable mechanical displacement. The striker is used to convert the micro-displacement of the piezoelectric ceramic actuator into a concentrated mechanical impact force. The ceramic capacitor is used to generate a standard charge pulse with known charge and precise amplitude by utilizing the change in electrode spacing caused by the mechanical impact.

[0009] Preferably, a channel extends between the outer walls of the housing, and a core detection component is fitted onto the outer surface of the channel.

[0010] Preferably, the rotary electromagnetic shielding cover assembly further includes two flanges and a micro stepper motor. The two flanges are connected to the two ends of the inner wall of the housing. The opposite sides of the two flanges are connected to the two sides of the outer wall of the first shielding cover. The opposite sides of the two flanges are provided with grooves.

[0011] Preferably, a deep groove ball bearing is embedded between the inner surfaces of the two grooves, three shielding support seats are connected to the opposite sides of the two flanges, and the six shielding support seats are used to conduct electromagnetic signals of the first shield. One side of the outer wall of each of the three shielding support seats is connected to the outer surface of a corresponding deep groove ball bearing, and a rotating shaft is connected to the inner surface of the two deep groove ball bearings.

[0012] Preferably, the two rotating shafts are connected to each other on opposite sides of the outer wall of the second shield, the two fan-shaped windows are symmetrically opened on the outer surface of the second shield, and each fan-shaped window is connected to two corresponding thick beryllium copper spring sheets on opposite sides.

[0013] Preferably, the top ends of the four thick beryllium copper springs are in contact with the inner surface of the first shield, a first gear is sleeved on the outer surface of one of the rotating shafts, a second gear is meshed with the outer wall of the first gear, one side of the outer wall of the micro stepper motor is bolted to one side of the outer wall of one of the flanges, and the rotating end of the micro stepper motor is rotatably connected to the second gear.

[0014] Preferably, the mechanical pulse calibration assembly further includes an annular support base and a fixed base. The outer surface of the annular support base is connected to the inner surface of the piezoelectric ceramic actuator, and a mounting base is connected to one side of the outer wall of the piezoelectric ceramic actuator.

[0015] Preferably, one side of the outer wall of the mounting base is connected to an L-shaped elastic hinge, and one side of the outer wall of the L-shaped elastic hinge is connected to one side of the outer wall of the firing pin.

[0016] Preferably, the top of the fixing base is connected to a connecting plate and a guide post, and the bottom of the fixing base is bolted to the outer surface of the channel. The outer wall of the guide post is provided with a guide hole.

[0017] Preferably, the inner surface of the guide hole and the outer surface of the striker are slidably connected, four polytetrafluoroethylene (PTFE) insulating pillars are symmetrically connected to one side of the outer wall of the connecting plate, a PCB board is connected between the outer surfaces of the four PTFE insulating pillars, and one side of the outer wall of the PCB board is welded to one side of the outer wall of the ceramic capacitor.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] In this invention, by leveraging the synergistic effect of a rotary electromagnetic shielding assembly and a mechanical pulse calibration assembly, precise anti-interference acquisition and online self-calibration of sensor signals in cable partial discharge detection are achieved. This differs from traditional, inefficient solutions relying on electronic filtering and external calibration, resulting in more accurate and reliable partial discharge detection. Firstly, the rotary electromagnetic shielding assembly, through a mechanical design involving the synchronous opening and closing of the first and second shielding covers and phase, physically isolates asynchronous electromagnetic noise through mechanical rotation, completely eliminating the signal distortion problem of traditional electronic filtering. Secondly, it dynamically adapts to the power frequency voltage phase, accurately capturing synchronous discharge pulses, thereby significantly reducing the interference of weak electromagnetic signals. The measurement of discharge signals carries the risk of distortion and the estimation of discharge quantity. At the same time, the piezoelectric ceramic actuator of the mechanical pulse calibration component works in conjunction with the mechanical striker group to overcome the bottleneck of traditional electronic calibration devices being susceptible to environmental interference. It uses an electrical signal to trigger mechanical impact, combined with the precise charge injection of the built-in ceramic capacitor, to generate a stable standard pulse. This allows the calibration process to be synchronized in situ with the sensor detection state, avoiding the installation state differences of traditional offline calibration. It enables real-time self-updating of sensitivity parameters, ensuring that the measurement accuracy remains stable and reliable throughout the entire range of scenarios from weak discharge to strong breakdown discharge. This accurately matches the requirements of the entire discharge range from weak discharge to strong breakdown. Attached Figure Description

[0020] Figure 1 This is a perspective view of the main structure of a partial discharge detector for cables according to the present invention.

[0021] Figure 2This is a three-dimensional cross-sectional view of a partial discharge detector for cables according to the present invention.

[0022] Figure 3 This is a diagram showing the positional relationship between the rotary electromagnetic shielding assembly and the mechanical pulse calibration assembly in a partial discharge detector for cables according to the present invention.

[0023] Figure 4 This is a three-dimensional structural view of a rotary electromagnetic shielding cover assembly in a partial discharge detector for cables according to the present invention.

[0024] Figure 5 This is a schematic diagram of the installation positions of the groove, shielding support, and deep groove ball bearing in a partial discharge detector for cables according to the present invention.

[0025] Figure 6 This is a schematic diagram showing the installation positions of the first gear, the micro stepper motor, and the second gear in a partial discharge detector for cables according to the present invention.

[0026] Figure 7 This is a three-dimensional structural view of the mechanical pulse calibration component in a partial discharge detector for cables according to the present invention;

[0027] Figure 8 This is a schematic diagram of the installation positions of the annular support, piezoelectric ceramic actuator, and mounting base in a partial discharge detector for cables according to the present invention.

[0028] Figure 9 This is a schematic diagram of the installation positions of the guide post, fixing base, and connecting plate in a partial discharge detector for cables according to the present invention.

[0029] Figure 10 This is a schematic diagram showing the installation positions of the polytetrafluoroethylene insulating column, PCB board, and ceramic capacitor in a partial discharge detector for cables according to the present invention.

[0030] In the diagram: 100, Housing; 200, Channel; 300, Rotary electromagnetic shielding cover assembly; 301, Flange; 302, First shielding cover; 303, Groove; 304, Shielding support base; 305, Deep groove ball bearing; 306, Rotating shaft; 307, Second shielding cover; 308, Fan-shaped window; 309, Thick beryllium copper spring; 310, First gear; 311, Micro stepper motor; 312, Second gear; 400, Mechanical pulse calibration assembly; 401, Annular support base; 402, Piezoelectric ceramic actuator; 403, Mounting base; 404, L-shaped elastic hinge; 405, Strike pin; 406, Guide post; 407, Fixing base; 408, Connecting plate; 409, PTFE insulating post; 410, PCB board; 411, Ceramic capacitor; 500, Core detection assembly. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] like Figures 1-3 As shown, this embodiment discloses a partial discharge detector for cables, comprising a housing 100, a rotary electromagnetic shielding cover assembly 300, and a mechanical pulse calibration assembly 400. The rotary electromagnetic shielding cover assembly 300 and the mechanical pulse calibration assembly 400 are respectively installed inside the housing 100, and the rotary electromagnetic shielding cover assembly 300 is provided on one side of the outer wall of the mechanical pulse calibration assembly 400.

[0033] like Figure 4 As shown, the rotary electromagnetic shielding cover assembly 300 includes a first shielding cover 302, a second shielding cover 307, two fan-shaped windows 308, and four thick beryllium copper springs 309. The first shielding cover 302 is used to achieve preliminary isolation from broad-spectrum and indiscriminate electromagnetic interference. The second shielding cover 307 is used to physically isolate asynchronous noise. The two fan-shaped windows 308 are symmetrically opened and are used to isolate asynchronous electromagnetic noise. The four thick beryllium copper springs 309 are used to fill the rotation gap between the first shielding cover 302 and the second shielding cover 307.

[0034] like Figure 8 as well as Figure 10 As shown, the mechanical pulse calibration component 400 includes a piezoelectric ceramic actuator 402, a striker 405, and a ceramic capacitor 411. The piezoelectric ceramic actuator 402 is used to convert electrical signal commands into precise and controllable mechanical displacement. The striker 405 is used to convert the micro-displacement of the piezoelectric ceramic actuator 402 into a concentrated mechanical impact force. The ceramic capacitor 411 is used to generate a standard charge pulse with known charge and precise amplitude by utilizing the change in the electrode spacing caused by the mechanical impact.

[0035] This embodiment primarily addresses existing partial discharge detectors for cables, such as high-frequency current transformers (HFCTs) for partial discharge detection. Their core detection process relies on the sensor's electromagnetic induction signal reception and the back-end algorithm's digital filtering. After signal amplification, digital-to-analog conversion, and software analysis, the discharge signal is identified and quantified. This purely electronic signal processing stage inherently suffers from background noise and susceptibility to environmental electromagnetic interference. This makes it difficult to accurately match the sensor's actual output signal with the real discharge pulse. In complex field detection processes, phenomena such as the effective signal being submerged, pulse polarity misjudgment, and inaccurate discharge quantity estimation frequently occur. Furthermore, the use of electronic filtering methods for noise reduction has inherent contradictions; the algorithm's filtering characteristics easily lead to signal distortion. It cannot adaptively match the nonlinear electromagnetic response changes caused by the diversity of field interference sources, differences in cable laying, and types of insulation defects. It struggles to extract effective signals when dealing with strong corona interference, misidentifies pulse sources when distinguishing noise from nearby equipment, and misses weak discharges in the initial detection phase due to insufficient signal-to-noise ratio. These issues lead to decreased detection reliability, misjudgment of defect types, and distorted equipment condition assessment conclusions.

[0036] This embodiment addresses the problems of existing technologies by utilizing the synergistic effect of a rotary electromagnetic shielding assembly 300 and a mechanical pulse calibration assembly 400 to achieve accurate anti-interference acquisition and online self-calibration of sensor signals in cable partial discharge detection. This differs from traditional, inefficient solutions relying on electronic filtering and external calibration, resulting in more accurate and reliable partial discharge detection. Firstly, the rotary electromagnetic shielding assembly 300, through its mechanical design of a first shielding cover 302, a second shielding cover 307, and phase-synchronized opening and closing, physically isolates asynchronous electromagnetic noise through mechanical rotation, completely eliminating the signal distortion problem of traditional electronic filtering. Secondly, it dynamically adapts to the power frequency voltage phase, accurately capturing synchronous discharge pulses. This significantly reduces the risk of measurement distortion and discharge quantity estimation deviation in weak discharge signals. At the same time, the piezoelectric ceramic actuator 402 and mechanical striker 405 of the mechanical pulse calibration component 400 work together to overcome the bottleneck of traditional electronic calibration devices being susceptible to environmental interference. The mechanical impact is triggered by an electrical signal, and the precise charge injection of the built-in ceramic capacitor 411 generates a stable standard pulse. This allows the calibration process to be synchronized in situ with the sensor detection state, avoiding the installation state differences of traditional offline calibration. It enables real-time self-updating of sensitivity parameters, ensuring that the measurement accuracy remains stable and reliable throughout the entire range of scenarios from weak discharge to strong breakdown discharge. This accurately matches the requirements of the entire discharge range from weak discharge to strong breakdown.

[0037] according to Figures 1-2 As shown, a channel 200 extends between the outer walls of the housing 100, and a core detection component 500 is fitted onto the outer surface of the channel 200.

[0038] In this embodiment of the invention, the channel 200 is designed as a cylindrical through hole that matches the outer diameter of the cable to be tested, allowing the cable to pass directly into the housing 100 without disassembling the sensor or adjusting the cable laying. During on-site installation, the core detection component 500 and the cable can be coaxially aligned simply by passing the cable through the channel 200. This effectively avoids the problem of poor electromagnetic coupling caused by the misalignment of the sensor and the cable in traditional testing. At the same time, the core detection component 500 is fitted outside the channel 200, forming a closed detection space with the rotary electromagnetic shielding cover component 300 and the mechanical pulse calibration component 400 inside the housing 100. This reduces the direct impact of external environmental interference on the detection component and further ensures the stability of signal acquisition.

[0039] according to Figure 5 As shown, the rotary electromagnetic shielding cover assembly 300 also includes two flanges 301 and a micro stepper motor 311. The two flanges 301 are connected to the inner walls of the housing 100 at both ends. The opposite sides of the two flanges 301 are connected to the outer walls of the first shielding cover 302. The opposite sides of the two flanges 301 are provided with grooves 303.

[0040] In this embodiment of the invention, firstly, the flange 301 is made of 304 stainless steel, which provides a stable support frame for the first shield 302, avoiding axial displacement of the traditional shield due to transportation bumps or on-site vibrations of the housing 100, and ensuring the integrity of the first shield 302. The micro stepper motor 311 is a 42 stepper motor with a step angle of 1.8° and a torque of 0.5 N·m, and is bolted to one of the flanges 301. During disassembly and assembly, only the bolts need to be removed to replace the micro stepper motor 311, without disassembling the entire shield assembly, thus solving the problems of difficult maintenance and high replacement cost of traditional integrated structures. Secondly, the groove 303 opened on the flange 301 is a circular stepped groove, and its inner diameter is tolerant to the outer ring diameter of the deep groove ball bearing 305, which can firmly fit and fix the deep groove ball bearing 305, preventing radial movement of the deep groove ball bearing 305 during rotation, laying the foundation for the precise rotation of the second shield 307.

[0041] according to Figure 5 As shown, deep groove ball bearings 305 are embedded between the inner surfaces of the two grooves 303. Three shielding support seats 304 are connected to the opposite side of the two flanges 301. The six shielding support seats 304 are used to conduct electromagnetic signals of the first shielding cover 302. One side of the outer wall of every three shielding support seats 304 is connected to the outer surface of a corresponding deep groove ball bearing 305. The inner surfaces of the two deep groove ball bearings 305 are connected to a rotating shaft 306.

[0042] In this embodiment of the invention, the deep groove ball bearing 305 is selected as a (608ZZ high-precision silent model), which can significantly reduce the resistance when the rotating shaft 306 rotates, enabling the micro stepper motor 311 to drive the second shield 307 to rotate smoothly. This reduces the energy consumption of the micro stepper motor 311 and avoids step loss due to excessive friction, ensuring the accuracy of phase synchronization. The shield support seats 304 are made of (H62 brass) and are evenly distributed at 120° on the inner side of the flange 301. Every three support seats are fixed to the outer ring of the deep groove ball bearing 305 by spot welding. The length protrudes 1mm beyond the outer ring of the bearing, which not only provides stable support for the bearing but also transmits the electromagnetic shielding effectiveness of the first shield 302 to the deep groove ball bearing 305, preventing the shielding structure from forming a break point and thus further improving the anti-interference capability. Secondly, the rotating shaft 306 is made of 45 steel (heat treated, with a hardness of HRC28-32) and has an interference fit with the inner ring of the deep groove ball bearing 305 to ensure that the two rotate synchronously without relative slippage, avoiding phase deviation caused by the gap between the rotating shaft 306 and the deep groove ball bearing 305, which can provide a guarantee for the precise alignment of the subsequent sector window 308.

[0043] according to Figure 5 As shown, the two rotating shafts 306 are connected to each other on opposite sides and the outer walls of the second shield 307. Two fan-shaped windows 308 are symmetrically opened on the outer surface of the second shield 307, and each fan-shaped window 308 is connected to two corresponding thick beryllium copper springs 309 on opposite sides.

[0044] In this embodiment of the invention, the rotating shaft 306 and the second shielding cover 307 are integrated by welding, which ensures that the second shielding cover 307 can rotate synchronously with the rotating shaft 306, thus ensuring no loose gaps and ensuring the accurate rotation trajectory of the fan-shaped window 308. Secondly, the two fan-shaped windows 308 are symmetrically opened on the cylindrical surface of the second shielding cover 307, and the window angle is designed to be 30°. This 30° design can match the ±15° peak value of the power frequency voltage in the high-incidence phase range of partial discharge of the cable. Furthermore, two thick beryllium copper spring sheets 309 are fixed on the upper and lower sides of each fan-shaped window 308 to ensure that the pressure of the thick beryllium copper spring sheets 309 when in contact with the inner wall of the first shielding cover 302 is uniform. This will not increase the rotational resistance due to excessive pressure, and it can also fit tightly to fill the gaps. The symmetrical design of the fan-shaped windows 308 allows the cable discharge signal to enter the core detection component 500 evenly from both sides of the second shielding cover 307, ensuring that the induced signal intensity of each turn of the HFCT coil is consistent and reducing the error in the discharge quantity estimation.

[0045] according to Figures 5-6As shown, the tops of the four thick beryllium copper springs 309 are in contact with the inner surface of the first shield 302. The outer surface of one of the rotating shafts 306 is fitted with a first gear 310. The outer wall of the first gear 310 is meshed with a second gear 312. One side of the outer wall of the micro stepper motor 311 is bolted to one side of the outer wall of one of the flanges 301, and the rotating end of the micro stepper motor 311 is rotatably connected to the second gear 312.

[0046] In this embodiment of the invention, firstly, the thick beryllium copper spring 309 is made of QBe2 beryllium copper alloy with an elastic modulus of 130 GPa. Its top is polished and makes sliding contact with the inner wall of the first shielding cover 302, thereby ensuring that the second shielding cover 307 rotates without jamming. The continuous contact between the thick beryllium copper spring 309 and the first shielding cover 302 can fill the rotation gap between them in real time, blocking asynchronous electromagnetic noise from seeping in through the gap and further improving the shielding effectiveness. Secondly, both the first gear 310 and the second gear 312 are made of POM engineering plastic material, and the module design is as follows: The gears have 14 and 7 teeth respectively, with a transmission ratio of 2:1. For every 2 revolutions of the micro stepper motor 311, the rotating shaft 306 rotates only 1 revolution. This reduction transmission design can solve the problem of phase misalignment caused by traditional non-reduction transmission. The meshing clearance between the first gear 310 and the second gear 312 is controlled at 0.02-0.03mm, and special grease is applied to the meshing point of the first gear 310 and the second gear 312 to reduce gear wear and avoid meshing noise affecting signal acquisition, ensuring that the shield can still work stably in extreme temperature environments.

[0047] according to Figure 7 As shown, the mechanical pulse calibration assembly 400 also includes an annular support 401 and a fixed base 407. The outer surface of the annular support 401 is connected to the inner surface of the piezoelectric ceramic actuator 402, and a mounting base 403 is connected to one side of the outer wall of the piezoelectric ceramic actuator 402.

[0048] In this embodiment of the invention, firstly, the annular support 401 is made of 6061 aluminum alloy. The inner diameter of the annular support 401 is fitted with the outer diameter of the channel 200 with a clearance and is fixed to the outer wall of the channel 200 by screws. This design allows the piezoelectric ceramic actuator 402 to be in close contact with the core detection component 500, thereby shortening the transmission path of the calibration pulse and reducing signal loss during transmission. Secondly, the mounting base 403 is made of 304 stainless steel. One end is connected to the output end of the piezoelectric ceramic actuator 402 by bolts, and the other end is fixed to the L-shaped elastic hinge 404 by laser welding. This allows the micro-displacement of the piezoelectric ceramic actuator 402 to be accurately transmitted to the striker 405, avoiding loss or deviation during force transmission.

[0049] according to Figure 10As shown, an L-shaped elastic hinge 404 is connected to one side of the outer wall of the mounting base 403, and one side of the outer wall of the L-shaped elastic hinge 404 is connected to one side of the outer wall of the firing pin 405.

[0050] In this embodiment of the invention, firstly, the L-shaped elastic hinge 404 is made of 65Mn spring steel, and its corner is machined into a 1mm radius arc transition, which can ensure the elastic reset performance of the hinge and avoid breakage caused by stress concentration. When the piezoelectric ceramic actuator 402 is energized and extends to push the striker 405 to strike the ceramic capacitor 411, the L-shaped elastic hinge 404 can drive the striker 405 to quickly reset by its own elasticity, without the need for an additional reset spring, which simplifies the component structure. Secondly, the connection between the hinge and the striker 405 is laser welded to ensure that there is no relative looseness between the two. The striker 405 is made of tungsten steel with a hardness of HRC65-68, and its top is machined into a hemispherical shape to avoid scratching the plates of the ceramic capacitor 411 during impact, thereby extending the service life of the ceramic capacitor 411.

[0051] according to Figure 9 As shown, the top of the fixing base 407 is connected to the connecting plate 408 and the guide post 406, and the bottom of the fixing base 407 is bolted to the outer surface of the channel 200. The outer wall of the guide post 406 is provided with a guide hole.

[0052] In this embodiment of the invention, firstly, the fixing base 407 is made of nylon 66 material, and its bottom is connected to the outer surface of the channel 200 by bolts. The connecting plate 408 is an epoxy glass cloth board, which is connected to the fixing base 407 by bolts and can provide stable support for the PCB board 410. Secondly, the guide post 406 is made of 45 steel, and the inner diameter of its guide hole is clearance-fitted with the outer diameter of the striker 405, which can forcibly restrict the striker 405 to move only along the axial direction, avoid the striker 405 from radially deviating during the impact, and ensure that the impact force is completely applied to the center of the plate of the ceramic capacitor 411.

[0053] according to Figure 10 As shown, the inner surface of the guide hole and the outer surface of the striker 405 are slidably connected. Four polytetrafluoroethylene insulating pillars 409 are symmetrically connected to one side of the outer wall of the connecting plate 408. A PCB board 410 is connected between the outer surfaces of the four polytetrafluoroethylene insulating pillars 409. One side of the outer wall of the PCB board 410 is welded to one side of the outer wall of the ceramic capacitor 411.

[0054] In this embodiment of the invention, firstly, the polytetrafluoroethylene insulating pillars 409 are made of pure polytetrafluoroethylene and are symmetrically fixed on the connecting plate 408. Their excellent insulation performance completely blocks the electromagnetic coupling between the PCB board 410 and the connecting plate 408 and the fixing base 407, preventing interference signals from the housing 100 or other metal parts from entering the ceramic capacitor 411. This ensures that the standard charge pulse generated by the ceramic capacitor 411 is pure and free of noise. Secondly, the PCB board 410 is made of FR-4 epoxy board with a solder resist layer printed on the surface. It is suspended and fixed by four insulating pillars to reduce contact interference between the PCB board 410 and other components. At the same time, the ceramic capacitor 411 is made of NPO high-frequency low-loss capacitor and is soldered onto the PCB board 410 using the 0402 surface mount technology. This allows the charge pulse generated by the ceramic capacitor 411 to be transmitted to the signal input terminal of the core detection component 500 without loss.

[0055] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A partial discharge detector for cables, characterized in that: The housing (100), the rotary electromagnetic shielding cover assembly (300), and the mechanical pulse calibration assembly (400) are respectively installed inside the housing (100). The rotary electromagnetic shielding cover assembly (300) and the mechanical pulse calibration assembly (400) are provided on one side of the outer wall of the mechanical pulse calibration assembly (400). The rotary electromagnetic shield assembly (300) includes a first shield (302), a second shield (307), two fan-shaped windows (308), and four thick beryllium copper springs (309). The first shield (302) is used to achieve preliminary isolation from broad-spectrum and indiscriminate electromagnetic interference. The second shield (307) is used to physically isolate asynchronous noise. The two fan-shaped windows (308) are symmetrically arranged and are used to isolate asynchronous electromagnetic noise. The four thick beryllium copper springs (309) are used to fill the rotation gap between the first shield (302) and the second shield (307). The mechanical pulse calibration component (400) includes a piezoelectric ceramic actuator (402), a striker (405), and a ceramic capacitor (411). The piezoelectric ceramic actuator (402) is used to convert electrical signal commands into precise and controllable mechanical displacement. The striker (405) is used to convert the micro-displacement of the piezoelectric ceramic actuator (402) into a concentrated mechanical impact force. The ceramic capacitor (411) is used to generate a standard charge pulse with known charge and precise amplitude by utilizing the change in electrode spacing caused by mechanical impact.

2. The partial discharge detector for cables according to claim 1, characterized in that: A channel (200) runs through the outer walls of the housing (100), and a core detection component (500) is fitted onto the outer surface of the channel (200).

3. The partial discharge detector for cables according to claim 2, characterized in that: The rotary electromagnetic shield assembly (300) also includes two flanges (301) and a micro stepper motor (311). The two flanges (301) are connected to the inner walls of the housing (100) at both ends. The opposite sides of the two flanges (301) are connected to the outer walls of the first shield (302). The opposite sides of the two flanges (301) are provided with grooves (303).

4. The partial discharge detector for cables according to claim 3, characterized in that: A deep groove ball bearing (305) is embedded between the inner surfaces of the two grooves (303). Three shielding support seats (304) are connected to the opposite sides of the two flanges (301). The six shielding support seats (304) are used to conduct electromagnetic signals of the first shield (302). One side of the outer wall of each of the three shielding support seats (304) is connected to the outer surface of a corresponding deep groove ball bearing (305). A rotating shaft (306) is connected to the inner surface of each of the two deep groove ball bearings (305).

5. The partial discharge detector for cables according to claim 4, characterized in that: The two rotating shafts (306) are connected to each other on opposite sides of the outer wall of the second shield (307), and the two fan-shaped windows (308) are symmetrically opened on the outer surface of the second shield (307), and each fan-shaped window (308) is connected to two corresponding thick beryllium copper springs (309) on opposite sides.

6. The partial discharge detector for cables according to claim 5, characterized in that: The top ends of the four thick beryllium copper springs (309) are in contact with the inner surface of the first shield (302). A first gear (310) is fitted on the outer surface of one of the rotating shafts (306). A second gear (312) is meshed with the outer wall of the first gear (310). One side of the outer wall of the micro stepper motor (311) is bolted to one side of the outer wall of one of the flanges (301), and the rotating end of the micro stepper motor (311) is rotatably connected to the second gear (312).

7. The partial discharge detector for cables according to claim 2, characterized in that: The mechanical pulse calibration assembly (400) also includes an annular support (401) and a fixed base (407). The outer surface of the annular support (401) is connected to the inner surface of the piezoelectric ceramic actuator (402), and a mounting base (403) is connected to one side of the outer wall of the piezoelectric ceramic actuator (402).

8. The partial discharge detector for cables according to claim 7, characterized in that: An L-shaped elastic hinge (404) is connected to one side of the outer wall of the mounting base (403), and one side of the outer wall of the L-shaped elastic hinge (404) is connected to one side of the outer wall of the firing pin (405).

9. The partial discharge detector for cables according to claim 8, characterized in that: The top of the fixed base (407) is connected to a connecting plate (408) and a guide post (406), and the bottom of the fixed base (407) is bolted to the outer surface of the channel (200). The outer wall of the guide post (406) is provided with a guide hole.

10. The partial discharge detector for cables according to claim 9, characterized in that: The inner surface of the guide hole is slidably connected to the outer surface of the striker (405). Four polytetrafluoroethylene insulating pillars (409) are symmetrically connected to one side of the outer wall of the connecting plate (408). A PCB board (410) is connected between the outer surfaces of the four polytetrafluoroethylene insulating pillars (409). One side of the outer wall of the PCB board (410) is welded to one side of the outer wall of the ceramic capacitor (411).

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