Coupler for partial discharge monitoring and packaging method thereof

Abstract

The invention relates to a coupler for partial discharge monitoring and a packaging method thereof, the coupler comprises a coupler body, the coupler body comprises a plurality of coupler modules which are stacked up and down and are connected in series, and each coupler module comprises a plurality of cores which are stacked up and down and are connected in parallel; each core comprises an intermediate medium and electrode layers arranged on the two sides of the intermediate medium, and the intermediate medium comprises medium layers and metal layers which are stacked up and down and are alternately arranged. The coupler for partial discharge monitoring is low in equivalent series inductance, high in resonant frequency and resistant to high voltage.

Description

Technical Field

[0001] This invention belongs to the field of electronic devices, specifically relating to a coupler for partial discharge monitoring and its packaging method. Background Technology

[0002] The stator winding is the core component of a generator, and the performance of its insulation system directly affects the safe operation of the generator set. During long-term operation, the winding insulation material is subjected to multiple stress coupling effects, including electrical, thermal, and mechanical stresses, gradually leading to molecular chain breakage, air gap formation, and interface deterioration, which may eventually result in insulation breakdown and other accidents. Therefore, its operating status should be dynamically monitored to identify early signs of faults and to perform maintenance before equipment performance degrades to a certain level or before a fault occurs, thereby reducing losses caused by downtime.

[0003] The stator windings of the generator are connected to a high-voltage coupler via cables. When insulation failure occurs inside the generator, the high-frequency signal generated by partial discharge is collected by the high-voltage coupler and transmitted to the detection instrument. The detection instrument uses indicators such as the frequency, discharge amplitude, pulse polarity, phase, and partial discharge quantity of the signals transmitted by multiple couplers to determine the degree, trend, and location of insulation failure.

[0004] A high-voltage coupler is essentially a high-voltage, small-capacity capacitor with a capacitance of 80pF ± 5%. At low frequencies, the capacitor has a relatively high capacitive reactance. As the frequency increases, the capacitive reactance gradually decreases, while the inductive reactance gradually increases. The frequency at which the impedance is minimum is the capacitor's resonant frequency. Through appropriate dielectric material design, structural design, and process design, the capacitor can exhibit a high impedance state for the 50Hz / 60Hz power grid fundamental frequency and a low impedance state for the partial discharge frequencies from 50MHz to 250MHz. This allows for the efficient coupling and transmission of high-frequency partial discharge signals to detection instruments.

[0005] Conventional thin-film capacitors have low resonant frequencies, rarely reaching 50MHz to 250MHz. Furthermore, the generator stator windings operate in harsh environments, including high voltage, high vibration, and high temperature. During energized use, thin-film dielectric materials gradually undergo electrical and thermal aging, making it difficult to guarantee a long lifespan. Therefore, there is a need to develop a high-voltage coupler suitable for partial discharge monitoring. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides a coupler for partial discharge monitoring, comprising a coupler body, wherein the coupler body comprises a plurality of coupler modules stacked vertically and connected in series with each other, and each coupler module comprises a plurality of cores stacked vertically and connected in parallel with each other.

[0007] Each core includes an intermediate dielectric and electrode layers disposed on both sides of the intermediate dielectric. The intermediate dielectric includes dielectric layers and metal layers stacked vertically and alternately.

[0008] Preferably, the thickness of the dielectric layer is 20–50 μm, and the thickness of the metal layer is 20–100 nm.

[0009] Preferably, the dielectric layer, metal layer, and electrode layer of the core are all circular and concentrically arranged, and the diameters of the metal layer and the electrode layer are equal and smaller than the diameter of the dielectric layer.

[0010] Preferably, the outer periphery of the electrode layer is provided with an electrode lead-out portion; within each coupler module, the electrode leads-out portions of the two electrode layers of each core are bent in opposite directions to connect with each other.

[0011] Preferably, the outer periphery of the dielectric layer is provided with a pair of cuts, which are arranged opposite to each other on the outer periphery; the electrode lead-out portion of the electrode layer is rectangular, and the position of the electrode lead-out portion of each electrode layer of the core corresponds to a cut-out.

[0012] Preferably, metal connecting blocks are provided between adjacent coupler modules, above the top coupler module, and below the bottom coupler module, and the metal connecting blocks are welded to their adjacent electrode layers;

[0013] Wiring rods are provided on the metal connecting blocks above the top coupler module and below the bottom coupler module.

[0014] Preferably, the electrode leads of the electrode layer above the intermediate medium are bent upwards, and the electrode leads of the electrode layer below are bent downwards; the upwardly bent electrode leads of each core of each coupler module are welded to the metal connecting block above the coupler module, and the downwardly bent electrode leads are welded to the metal connecting block below the coupler module.

[0015] Preferably, the material of the dielectric layer is mica or glass; and / or

[0016] The metal layer is made of one or two of silver, zinc, aluminum, and copper; the metal layer is formed by vapor deposition on the surface of the dielectric layer, or by printing electrode paste on the surface of the dielectric layer and then sintering.

[0017] Preferably, epoxy resin is provided between adjacent cores, and the outside of the coupler body is wrapped with epoxy resin.

[0018] Another aspect of the present invention provides a packaging method for packaging the aforementioned coupler for partial discharge monitoring, comprising:

[0019] The coupler body is placed in an impregnation device and heated and dried.

[0020] The coupler body is impregnated by injecting a first epoxy resin into the impregnation device under vacuum conditions.

[0021] Pressurize the coupler body and maintain pressure for a predetermined time;

[0022] The coupler body is moved into an oven and heated to cure the first epoxy resin;

[0023] The coupler body is placed in a potting mold, and a second epoxy resin is poured into the potting mold so that the second epoxy resin encapsulates the coupler body.

[0024] The potting mold containing the coupler body is moved into an oven and heated to cure the second epoxy resin.

[0025] The beneficial effects of this invention are as follows: Each coupler module and each core of the coupler is arranged along the normal direction of the dielectric layer and electrode layer. This arrangement allows for shorter lead connection distances, reducing the equivalent series inductance (ESL) of the coupler and thus increasing its resonant frequency. The intermediate dielectric of the core comprises alternating dielectric and metal layers stacked vertically, which hinders the migration of high-energy electrons within the intermediate dielectric, increases the breakdown electric field of the intermediate dielectric, and effectively avoids the drawback of the breakdown electric field strength decreasing with increasing thickness, significantly improving the coupler's high-voltage withstand capability. Furthermore, using a multilayered material for the intermediate dielectric effectively prevents electrical weaknesses from overlapping in the same location, improving the coupler's reliability. Moreover, mica and glass, as dielectric materials, possess the characteristics of high voltage resistance and long lifespan.

[0026] Tests show that the epoxy resin-impregnated coupler for partial discharge monitoring maintains a low impedance state in the range of 40MHz to 350MHz, completely covers the high voltage partial discharge frequency band, and maintains a high impedance to signals in other frequency bands, which can effectively detect and filter high voltage partial discharge signals.

[0027] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0028] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0029] Figure 1 A schematic diagram of the appearance of a coupler for partial discharge monitoring according to an embodiment of the present invention is shown.

[0030] Figure 2 A schematic diagram of the internal structure of a coupler for partial discharge monitoring according to an embodiment of the present invention is shown.

[0031] Figure 3 An exploded schematic diagram of the core of a coupler for partial discharge monitoring according to an embodiment of the present invention is shown.

[0032] Figure 4 A schematic diagram of a coupler module for partial discharge monitoring according to an embodiment of the present invention is shown.

[0033] Figure 5 A perspective view of a coupler for partial discharge monitoring according to an embodiment of the present invention is shown.

[0034] Figure 6 The test results of the monitoring frequency of a coupler for partial discharge monitoring according to an embodiment of the present invention are shown.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Coupler module; 2. Core; 3. Dielectric layer; 4. Metal layer; 5. Electrode layer; 6. Electrode lead-out part; 7. Cutout; 8. Metal connecting block; 9. Connecting rod; 10. Base; 11. Wire hole; 12. Annular protrusion. Detailed Implementation

[0037] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0038] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] refer to Figures 1 to 5 As shown, the present invention provides a coupler for partial discharge monitoring, including a coupler body, the coupler body including a plurality of coupler modules 1 stacked vertically and connected in series with each other, and each coupler module 1 including a plurality of cores 2 stacked vertically and connected in parallel with each other.

[0041] Each core 2 includes an intermediate dielectric and electrode layers 5 disposed on both sides of the intermediate dielectric. The intermediate dielectric includes dielectric layers 3 and metal layers 4 stacked on top of each other and arranged alternately.

[0042] The coupler for partial discharge monitoring of the present invention has each coupler module and each core arranged along the normal direction (i.e., the up and down direction) of the dielectric layer and electrode layer. This arrangement structure has a shorter lead connection distance, which can reduce the equivalent series inductance (ESL) of the coupler and thus improve its resonant frequency.

[0043] Furthermore, conventional capacitors often employ a relatively thick dielectric material between two electrode layers. According to the dielectric thin-layer strengthening effect, the thinner the dielectric layer, the higher the breakdown field strength. That is, as the dielectric layer thickness increases, the breakdown field strength decreases rapidly. The core of this invention comprises alternating dielectric and metal layers stacked vertically. Electrons travel a short distance within the dielectric layer before colliding with the metal layer, their speed decreasing, requiring them to re-accelerate from the metal layer until colliding with the next metal layer. Therefore, by alternating dielectric and metal layers, the migration of high-energy electrons within the intermediate dielectric can be hindered, increasing the breakdown electric field of the intermediate dielectric and effectively avoiding the drawback of the breakdown electric field strength decreasing with increasing thickness. This significantly improves the high-voltage withstand capability of the coupler. In addition, using a multilayered material for the intermediate dielectric can effectively prevent electrical weaknesses from overlapping in the same location, improving the reliability of the coupler.

[0044] Preferably, the dielectric layer is made of mica or glass, as mica and glass are characterized by high pressure resistance and long service life.

[0045] Figure 3 An exploded view of the core is shown to clearly illustrate its layered structure. (Reference) Figure 3As shown, the thickness of the dielectric layer 3 is 20–50 μm, preferably 30 μm. The metal layer 4 is made of one or two of silver, zinc, aluminum, and copper. The metal layer 4 can be formed by vapor deposition on the surface of the dielectric layer 3, or by printing electrode paste on the surface of the dielectric layer 3 and then sintering it. Figure 3 In this embodiment, a metal layer 4 is formed only on the upper surface of the dielectric layer 3. Alternatively, a metal layer 4 may be formed only on the lower surface of the dielectric layer 3. In other embodiments, to achieve more precise alignment of the metal layers 4 and smaller capacity differences, metal layers may be formed on both sides of the dielectric layer 3. These embodiments are all within the scope of the present invention. In any case, the total thickness of the metal layers between adjacent dielectric layers is 20–100 nm, preferably 30 nm. Figure 3 In this drawing, the thickness of metal layer 4 is not depicted to scale to better illustrate its thickness. The electrode layer 5 is made of one or two of the following materials: silver, zinc, aluminum, copper, and silver.

[0046] The dielectric layer 3, metal layer 4, and electrode layer 5 of the core 2 are all circular and concentrically arranged. The diameters of the metal layer 4 and the electrode layer 5 are basically equal and smaller than the diameter of the dielectric layer 3.

[0047] Electrode layers 5 cover both sides of the intermediate medium, and electrode leads 6 are provided on their outer periphery, preferably rectangular. Within each coupler module 1, the electrode leads 6 of the two electrode layers 5 of each core 2 are bent in opposite directions to connect with each other. Specifically, the electrode leads 6 of the electrode layers 5 above the intermediate medium of each core 2 are bent upwards and connected to each other; the electrode leads 6 of the electrode layers 5 below the intermediate medium of each core 2 are bent downwards and connected to each other. Alternatively, the electrode leads 6 of the electrode layers 5 above the intermediate medium of each core 2 are bent downwards and connected to each other; the electrode leads 6 of the electrode layers 5 below the intermediate medium of each core 2 are bent upwards and connected to each other. In this way, the parallel connection of the cores within the coupler module is achieved. Figure 4 In the embodiment shown, the electrode leads 6 of the electrode layer 5 above the intermediate medium of each core 2 are all bent upward, covering and connecting with each other, and the electrode leads 6 of the electrode layer 5 below the intermediate medium of each core 2 are all bent downward, covering and connecting with each other.

[0048] A pair of notches 7 are provided on the outer periphery of the dielectric layer 3, and the pair of notches 7 are arranged opposite each other on the outer periphery, that is, at both ends of a diameter. There is an electrode layer 5 on both the top and bottom of the core 2, and the position of the electrode lead-out portion 6 of each electrode layer 5 corresponds to a notch 7. In this way, the bent electrode lead-out portion 6 fits exactly against the notch 7.

[0049] Metal connecting blocks 8 are provided between adjacent coupler modules 1, above the top coupler module, and below the bottom coupler module. The metal connecting blocks 8 are made of one or two of silver, zinc, aluminum, and copper. The metal connecting blocks 8 are cylindrical, with a diameter equal to the diameter of the electrode layer 5.

[0050] The metal connecting block 8 is welded to the electrode lead-out portion 6 of the electrode layer 5 of the core 2. Specifically, in the coupler module 1, the upwardly bent electrode lead-out portion 6 of each core 2 extends to the lower surface of the metal connecting block 8 above the coupler module for welding, and the downwardly bent electrode lead-out portion 6 extends to the upper surface of the metal connecting block 8 below the coupler module for welding, thereby realizing the parallel connection of each core 2 inside the coupler module 1.

[0051] The metal connecting block 8 is also welded to the electrode layer 5 of the two adjacent cores 2, thereby connecting the two adjacent coupler modules 1 in series, and thus realizing the series connection of multiple coupler modules 1.

[0052] The metal connecting block 8 above the top coupler module and the metal connecting block 8 below the bottom coupler module are provided with connecting rods 9 for connecting to external devices via leads.

[0053] The coupler used for partial discharge monitoring also includes a base 10, which is disc-shaped with a through hole in the center for the connecting rod 9 to pass through, and an annular protrusion 12 on the outer periphery, with a wire hole 11 for the lead wire to pass through.

[0054] The height of the annular protrusion 12 is greater than the length of the bottom connecting rod, so that the coupler can be placed vertically and stably. The wire holes 11 can be n-shaped, and there can be multiple holes, evenly arranged along the circumference of the annular protrusion 12.

[0055] Epoxy resin is provided between adjacent cores 2 for insulation. The outside of the coupler body is wrapped with insulating materials such as epoxy resin.

[0056] The present invention also provides a method for packaging a coupler for partial discharge monitoring, comprising the following steps:

[0057] Step 1: Place the coupler body in an impregnation device and heat it to dry;

[0058] Step 2: Inject the first epoxy resin into the impregnation equipment under vacuum conditions to impregnate the coupler body;

[0059] Step 3: Apply pressure to the coupler body and maintain it for a predetermined time;

[0060] Step 4: Move the coupler body into the oven and heat it to cure the first epoxy resin;

[0061] Step 5: Place the coupler body in the potting mold and pour the second epoxy resin into the potting mold so that the second epoxy resin encapsulates the coupler body.

[0062] Step 6: Move the potting mold containing the coupler body into the oven for heating to cure the second epoxy resin.

[0063] Preferably, in step 1, the coupler body is placed laterally in the impregnation equipment, that is, the stacking direction of the coupler modules is horizontal, and the normal directions of the dielectric layer and metal layer of the core are set horizontally. This can save epoxy resin required for impregnation. The coupler body can be fixed in the impregnation equipment using special tooling. The heating and drying temperature is 125℃~180℃, preferably 150℃, and the time is 8~10 hours.

[0064] In step 2, the temperature inside the impregnation equipment is first lowered to 80°C, and then a vacuum of 1 Pa is achieved using a vacuum pump. This vacuum is maintained for 30–90 minutes before the first epoxy resin is injected into the impregnation equipment. The first epoxy resin must have a viscosity < 7000 Pa·s and a breakdown voltage > 20 kV / mm. Under vacuum conditions, the coupler body is impregnated for 4–8 hours.

[0065] In step 3, apply a gas pressure of 0.1–4 MPa and maintain it for 4–8 hours.

[0066] In step 4, the coupler body is moved into an oven for heating at a temperature of 125℃ to 180℃, preferably 150℃, for 8 to 10 hours. The coupler body is placed vertically inside the oven.

[0067] In step 5, the coupler body is placed in the center of the potting mold to ensure that the second epoxy resin can evenly coat the coupler body after potting. Positioning can be achieved using the connector rods on the coupler body. The second epoxy resin must meet the following requirements: breakdown voltage > 35kV / mm, water absorption rate < 0.1%.

[0068] In step 6, the heating temperature is 150℃~210℃, preferably 150℃, and the time is 8~10 hours.

[0069] As a preferred embodiment, in step 5, before injecting the second epoxy resin into the potting mold, the potting mold containing the coupler body can be preheated. The preheating temperature is 85℃~120℃, preferably 105℃, and the time is 15~60 minutes, preferably 30 minutes. After the injection is completed, ultrasonic vibration is performed for 5~30 minutes, preferably 15 minutes.

[0070] Example 1

[0071] The coupler for partial discharge monitoring in this embodiment includes a coupler body, which includes 15 coupler modules 1 stacked vertically and connected in series with each other. Each coupler module 1 includes 10 cores 2 stacked vertically and connected in parallel with each other.

[0072] Each core 2 includes an intermediate dielectric and electrode layers 5 disposed on both sides of the intermediate dielectric. The intermediate dielectric includes 15 dielectric layers 3, with metal layers 4 disposed between adjacent dielectric layers 3, i.e., the dielectric layers 3 and metal layers 4 form a stacked and alternating structure. The dielectric layer 3 is made of mica, has a thickness of 30 μm, and is circular with a diameter of 80 mm. A pair of symmetrical notches 7 are provided on the outer periphery of the dielectric layer 3, with a width l of 5 mm. The metal layer 4 has a thickness of 30 nm, a diameter of 70 mm, and is made of copper. The metal layer 4 is formed on the surface of the dielectric layer 3 by metal vapor deposition. The electrode layer 5 has a diameter of 70 mm, is made of copper foil, and has electrode leads 6 on its outer periphery. The electrode leads 6 are rectangular and have a width of 5 mm.

[0073] Metal connecting blocks 8 are provided between adjacent coupler modules, above the top coupler module, and below the bottom coupler module. The metal connecting blocks 8 are cylindrical, with a diameter of 70mm and a height of 2mm. The metal connecting blocks 8 are welded to the bent electrode leads 6 and to the electrode layers 5 of the two adjacent coupler modules, thus achieving parallel connection of the cores within the coupler module and series connection between the coupler modules. Connecting rods 9 are provided on the metal connecting blocks 8 above the top coupler module and below the bottom coupler module.

[0074] Example 2

[0075] The coupler for partial discharge monitoring in this embodiment includes a coupler body, which includes 20 coupler modules 1 stacked vertically and connected in series with each other. Each coupler module 1 includes 15 cores 2 stacked vertically and connected in parallel with each other.

[0076] Each core 2 includes an intermediate dielectric and electrode layers 5 disposed on both sides of the intermediate dielectric. The intermediate dielectric includes 20 dielectric layers 3, with metal layers 4 disposed between adjacent dielectric layers 3, i.e., the dielectric layers 3 and metal layers 4 form a stacked and alternating structure. The dielectric layer 3 is made of glass, has a thickness of 50 μm, is circular, and has a diameter of 80 mm. A pair of symmetrical notches 7 are provided on the outer periphery of the dielectric layer 3, with a width l of 10 mm. The metal layer 4 has a thickness of 50 nm, a diameter of 55 mm, and is made of silver. The metal layer 4 is formed on the surface of the dielectric layer 3 by printing electrode paste and then sintering. The electrode layer 5 has a diameter of 55 mm, is made of aluminum foil, and has electrode leads 6 on its outer periphery. The electrode leads 6 are rectangular and have a width of 10 mm.

[0077] Specifically, a 50nm thick silver paste layer is prepared by printing on the surface of dielectric layer 3, and these dielectric layers 3 are stacked to form an intermediate dielectric. Then, an electrode layer 5 made of aluminum foil is placed on the intermediate dielectric to obtain a core semi-finished product. The core semi-finished product is sintered at high temperature to sinter the silver paste, glass sheet, and aluminum foil into a monolithic structure, thus obtaining a usable core.

[0078] Metal connecting blocks 8 are provided between adjacent coupler modules, above the top coupler module, and below the bottom coupler module. The metal connecting blocks 8 are cylindrical, with a diameter of 55mm and a height of 3mm. The metal connecting blocks 8 are welded to the bent electrode leads 6 and to the electrode layers 5 of the two adjacent coupler modules, thus achieving parallel connection of the cores within the coupler modules and series connection between the coupler modules. Connecting rods 9 are provided on the metal connecting blocks 8 above the top coupler module and below the bottom coupler module.

[0079] Example 3

[0080] This embodiment provides a packaging method for packaging the couplers for partial discharge monitoring of embodiments 1 and 2, including the following steps:

[0081] Step 1: Place the coupler body sideways in the immersion equipment and heat it to dry at 150°C for 8 hours;

[0082] Step 2: Slowly cool down to 80℃, evacuate to 1Pa, maintain for 30 minutes, and then inject the first epoxy resin into the impregnation equipment under vacuum conditions to impregnate the coupler body. The impregnation time is 4 hours. The viscosity of the first epoxy resin is less than 7000Pa·s, and the breakdown voltage is greater than 20kV / mm.

[0083] Step 3: Pressurize the coupler body to 1 MPa and maintain it for 4 hours;

[0084] Step 4: Move the coupler body into the oven and heat it to cure the first epoxy resin. The heating temperature is 150℃ and the time is 8 hours.

[0085] Step 5: Place the coupler body in the potting mold and preheat it to 105℃ for 30 minutes. Then, inject the second epoxy resin into the potting mold to coat the coupler body. The second epoxy resin has a breakdown voltage greater than 35kV / mm and a water absorption rate of less than 0.1%. After potting, perform ultrasonic vibration for 15 minutes.

[0086] Step 6: Move the potting mold containing the coupler body into the oven for heating to cure the second epoxy resin. The heating temperature is 150℃ and the time is 8 to 10 hours.

[0087] After packaging, a coupler for partial discharge monitoring is obtained. Performance testing was performed on this coupler for partial discharge monitoring, and the test results are shown below. Figure 6 As shown in the figure, its detection frequency can completely cover the high-voltage partial discharge frequency band, and it maintains high impedance to other frequency bands, effectively detecting and filtering high-voltage partial discharge signals. This coupler for partial discharge monitoring can meet the requirements of 90kV~150kV lightning impulse; at 1.5 times the rated voltage, the partial discharge of the capacitor is less than 1pC.

[0088] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A coupler for partial discharge monitoring, characterized in that, The system includes a coupler body, which comprises multiple coupler modules stacked vertically and connected in series, and each coupler module comprises multiple cores stacked vertically and connected in parallel. Each core includes an intermediate dielectric and electrode layers disposed on both sides of the intermediate dielectric. The intermediate dielectric includes dielectric layers and metal layers stacked vertically and alternately.

2. The coupler for partial discharge monitoring according to claim 1, characterized in that, The thickness of the dielectric layer is 20–50 μm, and the thickness of the metal layer is 20–100 nm.

3. The coupler for partial discharge monitoring according to claim 1, characterized in that, The dielectric layer, metal layer, and electrode layer of the core are all circular and concentrically arranged. The diameters of the metal layer and the electrode layer are equal and smaller than the diameter of the dielectric layer.

4. The coupler for partial discharge monitoring according to claim 1, characterized in that, The outer periphery of the electrode layer is provided with electrode leads; within each coupler module, the electrode leads of the two electrode layers of each core are bent in opposite directions to connect with each other.

5. The coupler for partial discharge monitoring according to claim 4, characterized in that, The dielectric layer has a pair of cuts on its outer periphery, and the pair of cuts are arranged opposite to each other on the outer periphery; the electrode leads of the electrode layer are rectangular, and the position of the electrode lead of each electrode layer of the core corresponds to a cut.

6. The coupler for partial discharge monitoring according to claim 5, characterized in that, Metal connecting blocks are provided between adjacent coupler modules, above the top coupler module, and below the bottom coupler module. The metal connecting blocks are welded to their adjacent electrode layers. Wiring rods are provided on the metal connecting blocks above the top coupler module and below the bottom coupler module.

7. The coupler for partial discharge monitoring according to claim 6, characterized in that, The electrode leads of the electrode layer above the intermediate medium are bent upwards, and the electrode leads of the electrode layer below are bent downwards; the upwardly bent electrode leads of each core of each coupler module are welded to the metal connecting block above the coupler module, and the downwardly bent electrode leads are welded to the metal connecting block below the coupler module.

8. The coupler for partial discharge monitoring according to claim 1, characterized in that, The material of the dielectric layer is mica or glass; and / or The metal layer is made of one or two of silver, zinc, aluminum, and copper; the metal layer is formed by vapor deposition on the surface of the dielectric layer, or by printing electrode paste on the surface of the dielectric layer and then sintering.

9. The coupler for partial discharge monitoring according to claim 1, characterized in that, Epoxy resin is provided between adjacent cores, and the outside of the coupler body is wrapped with epoxy resin.

10. A packaging method for packaging a coupler for partial discharge monitoring according to any one of claims 1 to 9, characterized in that, include: The coupler body is placed in an impregnation device and heated and dried. The coupler body is impregnated by injecting a first epoxy resin into the impregnation device under vacuum conditions. Pressurize the coupler body and maintain pressure for a predetermined time; The coupler body is moved into an oven and heated to cure the first epoxy resin; The coupler body is placed in a potting mold, and a second epoxy resin is poured into the potting mold so that the second epoxy resin encapsulates the coupler body. The potting mold containing the coupler body is moved into an oven and heated to cure the second epoxy resin.

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