Test apparatus and method for electrical properties of composite interfaces of cable accessories

Abstract

This application relates to the field of testing technology and provides a testing device and method for the electrical characteristics of composite interfaces of cable accessories. The testing device includes: an insulating cylinder with a hollow structure; an upper pressure cap and a high-voltage electrode at the upper end of the insulating cylinder; and a lower pressure cap and a low-voltage electrode at the lower end of the insulating cylinder; test insertion / removal structures respectively installed on the inner walls of the upper and lower pressure caps; an insulating sample, which is a ring-shaped three-dimensional contact structure and can be detachably installed within the test insertion / removal structures; and a control circuit module electrically connected to the high-voltage and low-voltage electrodes for applying voltage to the insulating sample for testing. The testing device of this application more realistically simulates the 360° circumferential contact between the actual cable insulation and the additional rubber insulation, ensuring that the source of the interface pressure is consistent with actual working conditions.

Description

Technical Field

[0001] This application relates to the field of high voltage and insulation material interface breakdown characteristic testing technology, and in particular to a testing device and method for the electrical characteristics of composite interfaces of cable accessories. Background Technology

[0002] In current technology, the use of insulated power cables is increasing. Extensive field experience shows that the interface between cable accessories and cable connections—that is, between cable insulation and joint insulation—is most prone to breakdown.

[0003] Existing technologies offer numerous devices for testing the composite interface electrical characteristics of cable accessories. These devices are used to measure and study the mechanism of breakdown voltage occurrence, thereby improving the reliability of cable systems. However, current testing devices suffer from the following technical problems:

[0004] 1. In existing technologies, flat plate test models are usually used. The pressure mainly comes from external devices applying different pressures to the flat plate test model. This cannot truly simulate the formation mechanism of interface pressure in actual operation, resulting in a large deviation between the test results and the actual working conditions.

[0005] 2. The elasticity of cable insulation is closely related to parameters such as the elastic modulus, hardness, and tensile strength of its material; however, these parameters change with temperature. In actual operation, temperature variations cause corresponding changes in the elasticity of the cable insulation, which in turn affects the interfacial pressure between the cable insulation and cable accessory joints, ultimately significantly impacting the interface electrical properties.

[0006] 3. In the existing technology, the high-voltage and low-voltage electrodes in the flat plate test piece model are thin-sheet shaped, and there will be electric field distortion at their edges, resulting in inaccurate test data.

[0007] 4. In existing technologies, to test the electrical characteristics of the composite interface between cable accessories and cable insulation, insulation samples corresponding to the cable accessories and cable insulation are typically fabricated first. Then, a fixing device is used to secure the insulation sample. Some current fixing devices use multiple layers of acrylic panels, placing the insulation sample between adjacent layers and securing them with bolts. Others use multiple insulating rods to clamp and fix the insulation sample. However, existing fixing devices usually rely on manual adjustment of the bolts to clamp the insulation sample. This can lead to over- or under-clamping, resulting in inaccurate electrical characteristic test results. Furthermore, the installation and removal of the insulation sample is inconvenient, and after repeated tests, the insulation sample may be damaged or worn out. Summary of the Invention

[0008] The purpose of this application is to provide a testing device and method for the electrical characteristics of composite interfaces in cable accessories, in order to solve the above-mentioned technical problems existing in the prior art, mainly including the following:

[0009] The first aspect of this application provides a testing apparatus for the electrical characteristics of composite interfaces of cable accessories, comprising:

[0010] An insulating cylinder, wherein the insulating cylinder has a hollow structure, an upper pressure cover is provided at the upper end of the insulating cylinder, a high voltage electrode is installed on the upper pressure cover, and a lower pressure cover is correspondingly provided at the lower end of the insulating cylinder, a low voltage electrode is installed on the lower pressure cover;

[0011] A test insertion and removal structure is respectively installed on the inner wall of the upper pressure cover and the inner wall of the lower pressure cover;

[0012] An insulating specimen, wherein the insulating specimen is a ring-shaped three-dimensional contact structure, and the insulating specimen can be detachably installed within the test insertion structure;

[0013] A control circuit module is electrically connected to the high-voltage electrode and the low-voltage electrode respectively, and is used to apply voltage to the insulating sample for testing.

[0014] To further improve the implementation of this application, the following structure is specifically adopted: the insulation test specimen includes an accessory specimen and a replaceable cable specimen, wherein both ends of the replaceable cable specimen abut against the test insertion / removal structure.

[0015] The accessory sample is fitted onto the outer wall of the replaceable cable sample, and the accessory sample and the replaceable cable sample are interference-fitted. The replaceable cable sample is used to change the interface pressure between the accessory sample and the accessory sample.

[0016] To further improve the implementation of this application, the following structure is specifically adopted: the two ends of the replaceable cable sample are tapered.

[0017] To further improve the implementation of this application, the following structure is specifically adopted: the accessory sample includes a first semiconducting tube, a second semiconducting tube, and an external insulation. The first semiconducting tube and the second semiconducting tube are spaced apart and sleeved on the outer wall of the replaceable cable sample. The external insulation is sleeved on the outer wall of the first semiconducting tube and the second semiconducting tube, and the external insulation is integrally formed with the first semiconducting tube and the second semiconducting tube.

[0018] To further improve the implementation of this application, the following structure is specifically adopted: the middle position of the external insulating surface is a circular surface, the surfaces on both sides of the circular surface are circular arc surfaces transitioning from the circular surface to the end of the external insulation.

[0019] To further improve the implementation of this application, the following configuration structure is specifically adopted: In the radial direction, the opposite end structures of the first semiconducting tube and the second semiconducting tube are the same, each including a flat portion and an arc portion, wherein the flat portion is located between the arc portion and the replaceable cable sample, and in the axial direction, the top of the flat portion is lower than the top of the arc portion.

[0020] To further improve the implementation of this application, the following structure is specifically adopted: the lower pressure cover has a receiving cavity, and a heating component is provided in the receiving cavity.

[0021] Furthermore, to better realize this application, the following configuration structure is specifically adopted: the test insertion / removal structure includes:

[0022] Mounting base;

[0023] A sleeve assembly, which is mounted on the mounting base and is movable along the axial direction of the mounting base;

[0024] Support arms, a plurality of support arms are arranged circumferentially spaced along the sleeve assembly, wherein each support arm includes a rotating end and a clamping end, and the support arm is rotatably connected to the mounting base through the rotating end;

[0025] A support joint is provided between the support arm and the sleeve assembly, with one end of the support joint rotatably connected to the support arm and the other end rotatably connected to the sleeve assembly;

[0026] When the sleeve assembly moves, it drives the support joint to rotate, and the support joint causes the clamping ends of the multiple support arms to move closer to each other for clamping the insulating sample.

[0027] The second aspect of this application provides a method for testing the electrical characteristics of composite interfaces of cable accessories, using the aforementioned testing apparatus for the electrical characteristics of composite interfaces of cable accessories, and includes the following steps:

[0028] Fill the insulating cylinder with silicone oil so that the insulating sample is immersed in the silicone oil;

[0029] At least one physical parameter is adjusted by the testing device, including interface pressure, roughness, and temperature; wherein, the interface pressure between the replaceable cable sample and the accessory sample is adjusted by replacing the replaceable cable sample with one of different diameters.

[0030] Measure and record the adjusted physical parameters and breakdown voltage to obtain test data;

[0031] An analytical model was established based on the test data to analyze the impact of the physical parameters on the composite interface breakdown of cable accessories.

[0032] Furthermore, the roughness is adjusted by replacing the cable samples with different roughnesses.

[0033] This application has at least the following technical advantages over the prior art:

[0034] 1. The testing device for the electrical properties of composite interfaces of cable accessories provided in this application includes: an insulating cylinder, which includes an upper pressure cover and a lower pressure cover; a test insertion / extraction structure respectively installed on the inner wall of the upper pressure cover and the inner wall of the lower pressure cover; an insulating sample, which is a ring-shaped three-dimensional contact structure and can be detachably installed in the test insertion / extraction structure; and a control circuit module, which is electrically connected to the high-voltage electrode and the low-voltage electrode respectively, for applying voltage to the insulating sample for testing. The insulating sample in this application is a ring-shaped three-dimensional contact structure, which replaces the flat plate test piece model, realistically simulating the 360° circumferential contact between the cable insulation and the additional rubber insulation. This ensures that the source of interface pressure is consistent with actual working conditions. Moreover, the test insertion / extraction structure not only facilitates the rapid assembly and disassembly of the insulating sample but also significantly improves testing efficiency, while reducing model wear caused by frequent replacement of the insulating sample and extending the service life of the testing device.

[0035] 2. This application can more realistically simulate the coupling effect of multiple physical factors such as temperature field, interface pressure distribution and surface morphology characteristics in actual operating conditions, and fully reveal their influence mechanism on interface electrical properties, providing important theoretical basis and technical support for the design, optimization and operation and maintenance of cable joints. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the test apparatus in this application;

[0038] Figure 2 This is a three-dimensional structural diagram of the insulating cylinder in this application;

[0039] Figure 3 Top view of the insulating cylinder in this application;

[0040] Figure 4 yes Figure 3 Cross-sectional view along the AA direction;

[0041] Figure 5This is a three-dimensional structural schematic diagram of the insulating sample in this application;

[0042] Figure 6 yes Figure 5 Cross-sectional view along the BB direction;

[0043] Figure 7 This is a three-dimensional structural schematic diagram of the replaceable cable sample in this application;

[0044] Figure 8 This is a frontal view of the specimen attached to this application;

[0045] Figure 9 yes Figure 8 Cross-sectional view along the CC direction;

[0046] Figure 10 yes Figure 9 Enlarged view of a section of part F in the middle;

[0047] Figure 11 This is a three-dimensional schematic diagram of the specimen attached to this application;

[0048] Figure 12 This is a three-dimensional structural diagram of the experimental insertion and removal structure in this application;

[0049] Figure 13 This is a top view of the experimental insertion and removal structure in this application;

[0050] Figure 14 yes Figure 13 Cross-sectional view along the GG direction;

[0051] Figure 15 This is a schematic diagram of the support frame in this application;

[0052] Figure 16 This is a schematic diagram of the clamping unit in this application;

[0053] Figure 17 This is a schematic diagram of the supporting joint structure in this application.

[0054] In the picture:

[0055] 1000. Testing equipment;

[0056] 100. Test insertion and removal structure;

[0057] 10. Mounting base;

[0058] 20. Sleeve assembly; 21. Sleeve; 211. Support rod; 212. Support component; 2121. Support cavity; 22. Support frame; 221. Connecting part; 23. Shrinkage component;

[0059] 30. Support arm; 31. Rotating end; 32. Clamping end; 33. Clamping component; 331. Clamping unit; 3311. Receiving groove; 3312. Clamping part; 3313. Limiting part; 34. Clamping cavity; 35. Bending part;

[0060] 40. Support joint; 41. Rotation groove; 42. Limiting groove;

[0061] 200. Insulation sample; 201. Accessory sample; 2011. First semiconducting tube; 20111. Flat part; 20112. Arc part; 2012. Second semiconducting tube; 2013. External insulation; 20131. Circular surface; 20132. Arc surface; 202. Replaceable cable sample;

[0062] 300. Insulating cylinder; 301. Upper pressure cap; 302. High-voltage electrode; 303. Lower pressure cap; 3031. Receiving cavity; 304. Low-voltage electrode;

[0063] 500. Control circuit module;

[0064] 600. Heating components. Detailed Implementation

[0065] The following description provides many different embodiments or examples for implementing various features of this application. The elements and arrangements described in the specific examples below are only for concise expression of this application and are merely examples, not intended to limit this application.

[0066] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to represent selected embodiments of this application.

[0067] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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 refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0068] In this application, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" a first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0069] Existing technologies offer numerous devices for testing the composite interface electrical characteristics of cable accessories. These devices are used to measure and study the mechanism of breakdown voltage occurrence, thereby improving the reliability of cable systems. However, current testing devices suffer from the following technical problems:

[0070] 1. In actual working conditions, there is a 360° circumferential three-dimensional contact between the cable insulation and the cable accessory joint. The pressure between the cable insulation and the cable accessory joint mainly comes from the elasticity of the cable accessory joint itself after the interference fit between the cable insulation and the cable accessory joint. However, the existing technology usually uses a flat plate test model, and the pressure mainly comes from the different pressures applied to the flat plate test model by external devices. This cannot truly simulate the formation mechanism of interface pressure in actual operation, resulting in a large deviation between the test results and the actual working conditions.

[0071] 2. The elasticity of cable insulation is closely related to parameters such as the elastic modulus, hardness, and tensile strength of its material; however, these parameters change with temperature. In actual operation, temperature variations cause corresponding changes in the elasticity of the cable insulation, which in turn affects the interfacial pressure between the cable insulation and cable accessory joints, ultimately significantly impacting the interface electrical properties.

[0072] 3. In the existing technology, the high-voltage and low-voltage electrodes in the flat plate test piece model are thin-sheet shaped, and there will be electric field distortion at their edges, resulting in inaccurate test data.

[0073] 4. The design of cable accessories relies heavily on empirical formulas and lacks quantitative analysis of the influence of interface micromorphology (such as rubber surface roughness), resulting in unsatisfactory partial discharge suppression effects.

[0074] 5. In existing technologies, to test the electrical characteristics of the composite interface between cable accessory joints and cable insulation, insulation samples corresponding to the cable accessory joints and cable insulation are typically fabricated first. Then, a fixing device is used to secure the insulation sample. Some current fixing devices use multiple layers of acrylic panels, placing the insulation sample between adjacent layers and securing them with bolts. Others use multiple insulating rods to clamp and fix the insulation sample. However, existing fixing devices usually rely on manual adjustment of bolts to clamp the insulation sample. This can lead to over- or under-clamping, resulting in inaccurate electrical characteristic test results. Furthermore, the installation and removal of the insulation sample is inconvenient, and after repeated tests, the insulation sample may be damaged or worn away.

[0075] In view of this, this application provides a testing device and method for the electrical characteristics of composite interfaces of cable accessories to solve the above-mentioned technical problems existing in the prior art, mainly including the following:

[0076] Example 1:

[0077] Embodiment 1 of this application provides a testing device for the electrical characteristics of composite interfaces of cable accessories, such as... Figures 1-17 As shown, it includes:

[0078] The insulating cylinder 300 is cylindrical and hollow. For example, the main body of the insulating cylinder 300 is made of epoxy fiberglass, and its outer wall is vertically arranged with alternating skirts of varying lengths made of silicone material to eliminate interference from external environmental factors on the test results. An upper pressure cap 301 is provided at the upper end of the insulating cylinder 300. The upper pressure cap 301 is disc-shaped and detachably sealed to the upper end of the insulating cylinder 300. The upper pressure cap 301 is made of a transparent material, such as acrylic sheet, allowing real-time observation of the state of the insulating sample 200 inside the insulating cylinder 300. A high-voltage electrode 302 is installed on the upper pressure cap 301 to provide the high-voltage terminal required in the test circuit. A lower pressure cap 303 is correspondingly provided at the lower end of the insulating cylinder 300. The lower pressure cap 303 is disc-shaped and made of high-temperature resistant material, such as ceramic glass or microcrystalline glass. A low-voltage electrode 304 is installed on the lower pressure cap 303, which is used to provide the grounding terminal required in the test circuit. In this application, the upper pressure cap 301 and the lower pressure cap 303 are designed to be disc-shaped to ensure a uniform distribution of the electric field at the edges and avoid the risk of sample breakdown caused by local electric field concentration.

[0079] Test insertion and removal structures 100 are respectively installed on the inner walls of the upper pressure cover 301 and the lower pressure cover 303. For example, two test insertion and removal structures 100 are installed in the insulating cylinder 300. Each test insertion and removal structure 100 includes a connecting end and a clamping end. The connecting end of one test insertion and removal structure 100 is detachably connected to the inner wall of the upper pressure cover 301, and the clamping end is used to clamp one end of the insulating sample 200. The connecting end of the other test insertion and removal structure 100 is detachably connected to the inner wall of the lower pressure cover 303, and the clamping end is used to clamp the other end of the insulating sample 200. The two test insertion and removal structures 100 and the insulating sample 200 are coaxially arranged to avoid the insulating sample 200 being subjected to other external forces that could affect the accuracy of the test results.

[0080] The insulation specimen 200 is a ring-shaped three-dimensional contact structure. This ring-shaped three-dimensional contact structure replaces the flat plate model, realistically simulating the 360° circumferential contact between the cable insulation and the additional rubber insulation, ensuring that the source of interface pressure is consistent with actual working conditions. The insulation specimen 200 is detachably installed within the test insertion / removal structure 100. For example, the clamping end 32 of the test insertion / removal structure 100 is initially in an open state. First, one end of the insulation specimen 200 is placed in the sleeve assembly 20 of the test insertion / removal structure 100, which is connected to the lower pressure cover 303. Then, the upper pressure cover 301 is closed, and both ends of the insulation specimen 200 press against the sleeve assembly 20. The sleeve assembly 20 drives the support joint 40 to rotate, thereby causing the clamping ends 32 to move closer together, thus clamping the insulation specimen 200.

[0081] The test insertion and removal structure 100 in this application is a reusable mechanical insertion and removal structure. The test insertion and removal structure 100 not only facilitates the rapid assembly and disassembly of the insulation sample 200, but also significantly improves the testing efficiency. At the same time, it reduces the model wear caused by frequent replacement of the insulation sample 200, extends the service life of the testing device, and provides a more scientific, accurate and efficient solution for testing the electrical characteristics of composite interfaces of cable accessories. It has important engineering application value.

[0082] The control circuit module 500 is electrically connected to the high-voltage electrode 302 and the low-voltage electrode 304, respectively, and is used to apply voltage to the insulating sample 200 for testing. For example, the control circuit module 500 uses an insulating material dielectric strength testing device. The device uses a variable low-voltage sinusoidal power supply to supply a step-up transformer to obtain the test voltage. The voltage is adjusted by computer control, ensuring a uniform and stable voltage increase rate. The secondary rated current of the high-voltage transformer is not less than 0.1A to ensure the device is not burned out at the moment of breakdown. The voltage regulator should be able to adjust the voltage uniformly, and its capacity should be the same as the capacity of the test transformer. Voltage measurement should be performed at the high-voltage end using a high-voltage electrostatic meter of class 2.5 or a voltage divider, with an error of less than ±4%. The control circuit is as follows: Figure 1 As shown, K1 is a power switch, T1 is a voltage regulating transformer, V is a voltmeter, T2 is a high-voltage transformer, and K2 is an overcurrent relay.

[0083] Therefore, the test device for the electrical characteristics of the composite interface of cable accessories provided in this application includes: an insulating cylinder 300, which includes an upper pressure cover 301 and a lower pressure cover 303; a test insertion and removal structure 100, which is respectively installed on the inner wall of the upper pressure cover 301 and the inner wall of the lower pressure cover 303; an insulating sample 200, which is an annular three-dimensional contact structure and can be detachably installed in the test insertion and removal structure 100; and a control circuit module 500, which is electrically connected to the high voltage electrode 302 and the low voltage electrode 304, and is used to apply voltage to the insulating sample 200 for testing. The insulation specimen 200 of this application is a ring-shaped three-dimensional contact structure. The ring-shaped three-dimensional contact structure replaces the flat plate test piece model, which truly simulates the 360° circumferential contact between the cable insulation and the additional rubber insulation. This ensures that the source of the interface pressure is consistent with the actual working conditions. Moreover, the test plug-in structure 100 not only facilitates the rapid assembly and disassembly of the insulation specimen 200, but also significantly improves the testing efficiency. At the same time, it reduces the model wear caused by frequent replacement of the insulation specimen 200 and extends the service life of the testing device.

[0084] According to some alternative embodiments, the insulation test specimen 200 includes an accessory specimen 201 and a replaceable cable specimen 202. The accessory specimen 201 is a specimen of a cable accessory joint, and the replaceable cable specimen 202 is a specimen of cable insulation. Both ends of the replaceable cable specimen 202 abut against the socket 21 in the test insertion and removal structure 100.

[0085] The accessory sample 201 is fitted onto the outer wall of the replaceable cable sample 202, and the accessory sample 201 and the replaceable cable sample 202 are interference-fitted. The replaceable cable sample 202 is used to change the interface pressure between it and the accessory sample 201.

[0086] In some alternative embodiments, the replaceable cable sample 202 is cylindrical, and the accessory sample 201 is also cylindrical. The accessory sample 201 is fitted onto the outer wall of the replaceable cable sample 202 with an interference fit to form a ring-shaped three-dimensional contact structure. Using a ring-shaped three-dimensional contact model instead of a flat plate model realistically simulates the 360° circumferential contact between the cable insulation and the additional rubber insulation, ensuring that the source of the interface pressure is consistent with actual working conditions.

[0087] For example, the replaceable cable specimen 202 has a length of 220 mm and an outer diameter ranging from 36 to 44 mm. By fabricating multiple replaceable cable specimens 202 with different diameters, different interference fit requirements between them and the accessory specimen 201 can be achieved, thus satisfying the different interface pressures that need to be simulated between the replaceable cable specimen 202 and the accessory specimen 201. In this application, the accessory specimen 201 does not need to be replaced; only the replaceable cable specimens 202 with different diameters need to be replaced to realistically simulate the different pressures between the cable insulation and the cable accessory joint, making the test data consistent with actual working conditions.

[0088] According to some alternative embodiments, the two ends of the replaceable cable sample 202 are smooth tapered, that is, the diameter of the replaceable cable sample 202 gradually decreases near the end. In this way, the accessory sample 201 can be easily fitted onto the outer wall of the replaceable cable sample 202 along the tapered surface of either end of the replaceable cable sample 202, avoiding damage to the inner wall of the accessory sample 201 by the end of the replaceable cable sample 202.

[0089] According to some optional embodiments, the accessory sample 201 includes a first semiconducting tube 2011, a second semiconducting tube 2012, and an external insulation 2013. The first semiconducting tube 2011 and the second semiconducting tube 2012 are spaced apart and fitted onto the outer wall of the replaceable cable sample 202. For example, the first semiconducting tube 2011 and the second semiconducting tube 2012 are cylindrical, and the spacing between them is set to 10.0 ± 0.1 mm. This dimensional design meets the insulation strength test requirements specified in GB / T 1408.1 and facilitates the accurate calculation of interface dielectric parameters. The external insulation 2013 is fitted onto the outer wall of the first semiconducting tube 2011 and the outer wall of the second semiconducting tube 2012, and is integrally formed with the first semiconducting tube 2011 and the second semiconducting tube 2012. For example, the external insulation 2013 wraps the opposite ends of the first semiconducting tube 2011 and the second semiconducting tube 2012 in the inner wall, and the other ends of the first semiconducting tube 2011 and the second semiconducting tube 2012 extend beyond the two ends of the external insulation 2013. The test insertion and removal structure 100 can clamp the two ends of the first semiconducting tube 2011 and the second semiconducting tube 2012 that extend beyond the external insulation 2013, so as to realize the connection between the first semiconducting tube 2011 and the second semiconducting tube 2012 and the high voltage electrode 302 and the low voltage electrode 304, respectively.

[0090] In the above scheme, the preparation of accessory sample 201 adopts a composite injection rubber molding process and a split mold design, with separate molds for the semiconducting tube and the integral accessory sample. Specifically, insulating rubber is first injected into the semiconducting tube mold to prepare the first semiconducting tube 2011 and the second semiconducting tube 2012. Then, the first semiconducting tube 2011 and the second semiconducting tube 2012 are placed and assembled in the integral accessory sample mold. A positioning pin system ensures that the integral accessory sample mold, the first semiconducting tube 2011, and the second semiconducting tube 2012 are placed coaxially. Then, cross-linked polyethylene material is injected a second time to form external insulation 2013. After the external insulation 2013 is cured, it forms an integral accessory sample 201 that fits perfectly with the first semiconducting tube 2011 and the second semiconducting tube 2012 without gaps. This type of insulating structure ensures that the electric field strength from the cable body to the inside of the joint is uniform and continuous, greatly reducing the risk of partial discharge, which is the main cause of insulation degradation and eventual breakdown.

[0091] According to some optional embodiments, the middle position of the surface of the external insulation 2013 is a ring surface 20131, and the surfaces on both sides of the ring surface 20131 transition to the end of the external insulation 2013 with an arc surface 20132. Exemplarily, the arc surface 20132 is recessed towards the replaceable cable sample 202. The diameter of the arc surface 20132 is 110mm. This configuration increases the creepage distance, greatly reducing flashover caused by external factors such as dirt and moisture, minimizing external interference, effectively suppressing surface discharge, and making the test results more accurate and reliable.

[0092] According to some alternative embodiments, in the radial direction, the opposite end structures of the first semiconducting tube 2011 and the second semiconducting tube 2012 are the same, both including a flat portion 20111 and an arc portion 20112. The flat portion 20111 is located between the arc portion 20112 and the replaceable cable sample 202. The flat portion 20111 is connected to the arc portion 20112, and a step is formed at the connection between the two. In the axial direction, the top of the flat portion 20111 is lower than the top of the arc portion 20112, that is, the arc portion 20112 protrudes from the flat portion 20111. In this way, part of the inner wall of the external insulation 2013 is embedded in the gap formed by the arc portion 20112 and the flat portion 20111, thereby enhancing the stability of the accessory sample 201 and increasing its tensile strength.

[0093] In some alternative embodiments, the radial dimension d of the planar portion 20111 is 1-1.5 mm, which facilitates external rubber injection molding.

[0094] In some alternative embodiments, the size of the planar portion 20111 is smaller than the diameter of the arc portion 20112 in the radial direction, which facilitates the secure forming between the external insulation 2013 and the first semiconducting tube 2011 and the second semiconducting tube 2012.

[0095] In some optional implementations, the plane of the flat portion 20111 is coplanar with the diameter of the arc portion 20112, which facilitates processing and adhesive injection.

[0096] According to some alternative embodiments, the lower pressure cover 303 has a receiving cavity 3031, in which a heating component 600 is disposed.

[0097] In the above scheme, the heating component 600 may include a heating wire and a switch, which are electrically connected. The heating wire is fixedly installed in the receiving cavity 3031, and the switch is installed on the side wall of the lower pressure cover 303. When a test is conducted, the heating temperature of the heating wire is controlled by the switch to heat the silicone oil in the insulating cylinder 300. The temperature range of the heated silicone oil is 20-90℃.

[0098] According to some alternative embodiments, the test insertion / removal structure 100 includes:

[0099] Mounting base 10 is used to detachably mount the test insertion and removal structure 100 in the test device 1000 for testing the electrical characteristics of the composite interface of cable accessories, wherein the test insertion and removal structure 100 clamps the insulation sample 200 in the test device 1000. For example, the mounting base 10 can be detachably mounted in the test device 1000 by means of bolts.

[0100] In some alternative embodiments, the mounting base 10 can be configured as a mounting plate structure, and the mounting base 10 can be configured as a square, rectangle, etc., without limitation. In this application, the mounting base 10 is configured as a circle to adapt to the shape of the test device 1000.

[0101] Sleeve assembly 20 is mounted on mounting base 10 and is movable along the axial direction of mounting base 10.

[0102] For example, one end of the sleeve assembly 20 is connected to the mounting base 10 via a shrink member 23, and the other end is a free end with a cavity that can accommodate the end of the insulating sample 200. The end of the insulating sample 200 can be installed in the free end of the sleeve assembly 20. During the installation of the insulating sample 200, a downward force is applied to the sleeve assembly 20, causing the sleeve assembly 20 to move closer to the mounting base 10. After the insulating sample 200 is removed, the sleeve assembly 20 moves away from the mounting base 10 under the force of the shrink member 23, returning to its initial state. In this application, the diameter of the sleeve assembly 20 is greater than or equal to the maximum diameter of the ends of multiple insulating samples 200 of different specifications, making the sleeve assembly 20 suitable for accommodating insulating samples of different specifications, thus having a wide range of applications.

[0103] Support arms 30 are arranged circumferentially around the sleeve assembly 20, meaning that multiple support arms 30 are arranged around the sleeve assembly 20, so that the sleeve assembly 20 is located within the space defined by the multiple support arms 30, facilitating the smooth entry of the insulating sample 200 into the sleeve assembly 20 through the space defined by the multiple support arms 30. Each support arm 30 includes a rotating end 31 and a clamping end 32. The support arm 30 is rotatably connected to the mounting base 10 via the rotating end 31. For example, a rotating component is mounted on the mounting base 10, and the rotating end 31 of the support arm 30 is rotatably connected to the rotating component via a pin. The clamping end 32 of the support arm 30 is a free end, located away from the mounting base 10 and above the sleeve assembly 20, used to clamp the insulating sample 200. In this application, multiple support arms 30 are used, and the clamping of the insulating sample 200 is achieved by the multiple support arms 30 being close to each other. The multiple support arms 30 can clamp insulating samples 200 of different specifications.

[0104] In some alternative embodiments, the number of support arms 30 is 2, 3, 4, etc., and in this application, the number of support arms 30 is preferably 3.

[0105] A support joint 40 is disposed between the support arm 30 and the sleeve assembly 20. One end of the support joint 40 is rotatably connected to the support arm 30, and the other end is rotatably connected to the sleeve assembly 20. For example, one end of the support joint 40 is rotatably connected to the support arm 30 near its lower end, and the other end is rotatably connected to the sleeve assembly 20 near its mounting base 10. The support joint 40 is tilted towards the mounting base 10, which allows the sleeve assembly 20 to pull the support joint 40 with a small force, thereby causing the multiple support arms 30 to move closer together to clamp the insulating sample 200. This also prevents the support joint 40 from jamming during movement.

[0106] When the sleeve assembly 20 moves, it drives the support joint 40 to rotate. The support joint 40 causes the clamping ends 32 of the multiple support arms 30 to move closer or further apart to clamp the insulating sample 200. For example, when the test insertion / removal structure 100 is in its initial state, the sleeve assembly 20 is positioned away from the mounting base 10, and the multiple support arms 30 are in an open state away from the sleeve assembly 20. When it is necessary to clamp the insulating sample 200, the end of the insulating sample 200 enters the cavity of the end of the sleeve assembly 20 away from the mounting base 10. The insulating sample 200 then exerts a downward force on the sleeve assembly 20. Under this force, the sleeve assembly 20 moves closer to the mounting base 10, simultaneously driving the multiple support joints 40 to move closer to the mounting base 10. The multiple support joints 40 drive the corresponding multiple support arms 30 to move closer to the sleeve assembly 20, clamping the insulating sample 200. The disassembly process of the insulating sample 200 is the reverse of the installation process and will not be described in detail here.

[0107] Therefore, the test insertion and removal structure 100 provided in this application is used to clamp an insulating sample 200, including a mounting base 10, a sleeve assembly 20, multiple support arms 30, and multiple support joints 40. The sleeve assembly 20 is disposed on the mounting base 10, and the multiple support arms 30 are arranged at intervals along the circumference of the sleeve assembly 20, and each support arm 30 is connected to the sleeve assembly 20 through a corresponding support joint 40. When it is necessary to clamp the insulating sample 200, the end of the insulating sample 200 enters the cavity of the sleeve assembly 20, and the sleeve assembly 20 is moved towards the mounting base 10. Then, by driving the support joints 40 to move, the multiple support arms 30 are moved closer to each other, thereby clamping the insulating sample 200. The sleeve assembly 20 and support arm 30 in the test insertion and removal structure 100 of this application can be used to clamp insulation samples 200 of different specifications without damaging the surface of the insulation sample 200. At the same time, the test insertion and removal structure 100 not only facilitates the quick assembly and disassembly of the insulation sample 200, but also significantly improves the testing efficiency, reduces the damage and wear of the insulation sample 200 caused by frequent operation, and extends the service life of the insulation sample 200 and the test insertion and removal structure 100. It provides a more scientific, accurate and efficient solution for testing the electrical characteristics of composite interfaces of cable accessories, and avoids affecting the accuracy of test results.

[0108] According to some alternative embodiments, the sleeve assembly 20 is vertically mounted on the mounting base 10 and coaxially arranged with the mounting base 10. The sleeve assembly 20 includes: a sleeve 21, a support frame 22, and a shrink member 23, with the support frame 22 located between the sleeve 21 and the shrink member 23, and the three are coaxially arranged. The sleeve 21 has a cavity in the direction away from the mounting base 10 for accommodating the end of the insulating sample 200.

[0109] One end of the shrink member 23 is fixedly connected to the mounting base 10, and the other end is fixedly connected to the lower surface of the support frame 22. The shrink member 23 can extend and retract axially. The initial height of the shrink member 23 in the vertical direction is the movable stroke of the sleeve assembly 20 relative to the mounting base 10. The upper surface of the support frame 22 is connected to the sleeve 21 to provide support force to the sleeve 21 to support the insulating sample 200. The side wall of the support frame 22 is rotatably connected to one end of the support joint 40. When the sleeve 21 moves, the support frame 22 can drive the support joint 40 to move closer or further away from each other. For example, the side wall of the support frame 22 is the wall close to the support joint 40. The support frame 22 is a disc, and multiple connecting parts 221 are provided on the side wall of the disc. Each connecting part 221 is correspondingly provided with the support joint 40. When the support frame 22 moves axially, it can ensure that multiple support joints 40 are also driven to move axially at the same time, thereby driving multiple support arms 30 to move closer or further away from each other.

[0110] According to some alternative embodiments, a plurality of connecting portions 221 are provided on the side wall of the support frame 22, and the plurality of connecting portions 221 are rotatably connected to each support joint 40.

[0111] In some alternative embodiments, the number of connecting portions 221 corresponds to the number of supporting joints 40. Each connecting portion 221 is a connecting rod, with one end fixedly connected to the lower end of the sleeve 21 and the other end rotatably connected to the end of the supporting joint 40. The connecting portions 221 extend horizontally, ensuring that the supporting joint 40 has sufficient rotational space and avoiding interference with the sleeve 21 or the retractable member 23.

[0112] According to some alternative embodiments, the shrink member 23 includes a first shrink member and a second shrink member;

[0113] The first shrinkable member is fixedly connected to the mounting base 10. The first shrinkable member has a shrinkage cavity in which an elastic element is installed. One end of the second shrinkable member is inserted into the shrinkage cavity and connected to the elastic element, and the other end of the second shrinkable member is connected to the lower surface of the support frame 22. For example, both the first and second shrinkable members can be tubular, and the elastic element is a spring. The second shrinkable member moves up and down along the shrinkage cavity of the first shrinkable member, thereby realizing the axial movement of the sleeve 21 and enabling the sleeve 21 to automatically return to its initial state.

[0114] In some alternative embodiments, the retractor 23 may be a spring.

[0115] According to some optional embodiments, a clamping unit 331 is installed on the clamping end 32 of the support arm 30. The clamping unit 331 has a receiving groove 3311. When multiple support arms 30 are close together, multiple clamping units 331 are spliced ​​to form a clamping member 33. Multiple receiving grooves 3311 form the clamping cavity 34 of the clamping member 33. The insulating sample 200 passes through the clamping cavity 34 and is clamped by the clamping member 33. The clamping member 33 formed by splicing multiple clamping units 331 and the clamping cavity 34 of the clamping member 33 formed by multiple receiving grooves 3311 can clamp insulating samples 200 of different specifications, and has a wide range of applications.

[0116] In the above scheme, multiple clamping units 331 are joined together to form a clamping member 33, which is circular, and the clamping cavity 34 is also circular. In some optional embodiments, the shapes of the clamping member 33 and the clamping cavity 34 match the shape of the outer wall of the clamping position of the insulating sample 200.

[0117] According to some alternative embodiments, the clamping unit 331 includes a clamping part 3312 and a limiting part 3313. The outer wall of the clamping part 3312 is fixedly connected to the clamping end 32. The lower end of the clamping part 3312 is perpendicularly connected to the limiting part 3313 to define a receiving groove 3311. The perpendicular connection between the lower end of the clamping part 3312 and the limiting part 3313 will form a limiting step.

[0118] In the above scheme, the clamping part 3312 is a ring structure, which is suitable for the outer wall shape of the insulating sample 200. The limiting part 3313 can abut against the protrusion on the outer wall of the insulating sample 200 to avoid the insulating sample 200 applying too much force to the sleeve assembly 20, causing the sleeve assembly 20 to be unable to return to the initial state.

[0119] In some alternative embodiments, the clamping part 3312 and the limiting part 3313 are integrally formed.

[0120] According to some optional embodiments, the sleeve 21 includes a support rod 211 and a support member 212. One end of the support rod 211 is connected to the upper surface of the support frame 22, and the other end is fixedly connected to the support member 212. The end of the support member 212 away from the support rod 211 has an opening. The support member 212 has a support cavity 2121, which communicates with the clamping cavity 34. This allows the insulating sample 200 to enter the support cavity 2121 through the clamping cavity 34, so that the insulating sample 200 is subjected to a horizontal clamping force in the clamping cavity 34 and a vertical supporting force from the support cavity 2121. Together, these forces ensure the stability of the insulating sample 200 in the testing device 1000 and ensure the smooth progress of the test.

[0121] In some alternative embodiments, the support rod 211 and the support member 212 can be detachably connected or integrally formed, and there is no limitation on this.

[0122] According to some optional embodiments, a rotation groove 41 is provided at one end of the support joint 40, and one end of the connecting part 221 is inserted into the rotation groove 41. A limiting groove 42 is provided at the other end of the support joint 40. The support arm 30 passes through the limiting groove 42 and can rotate relative to the limiting groove 42. At the same time, the rotation range of the support arm 30 is limited to avoid excessive rotation and failure to reset.

[0123] In the above scheme, one end of the connecting part 221 can be connected to the support joint 40 through a rotating shaft, and the end of the support joint 40 can also be connected to the support arm 30 through a rotating shaft.

[0124] According to some alternative embodiments, the support arm 30 has a bent portion 35 connected to the support joint 40. The support arm 30 is in the shape of a less than sign. By providing the bent portion 35, the clamping end 32 of the support arm 30 is brought close to the sleeve assembly 20. In this way, the sleeve assembly 20 only needs to move a small distance axially to achieve clamping of the insulating sample 200 by the clamping units 331 of the multiple clamping ends 32.

[0125] Example 2:

[0126] Embodiment 2 of this application provides a method for testing the electrical characteristics of composite interfaces of cable accessories, using the aforementioned testing device for the electrical characteristics of composite interfaces of cable accessories, and includes the following steps:

[0127] Fill the insulating cylinder 300 with silicone oil so that the insulating sample 200 is immersed in the silicone oil. For example, a high-performance silicone oil with a viscosity of 10,000 can be used to ensure the accuracy of the test data.

[0128] At least one physical parameter, including interface pressure, roughness, and temperature, is adjusted using a testing device. Specifically, the interface pressure between the replaceable cable sample 202 and the accessory sample 201 is adjusted by replacing the replaceable cable sample 202 with samples of different diameters. The silicone oil in the insulating cylinder 300 is heated electrically by a heating system and kept constant at a preset temperature. The influence of physical parameters such as pressure and roughness on the composite interface breakdown of the cable accessory at this preset temperature is studied. A voltage is applied to the insulating sample 200 through a control circuit module 500 to simulate the effect of an electric field. When the breakdown voltage is less than 20kV, the voltage is increased by 1kV / s; when the breakdown voltage is greater than or equal to 20kV, the voltage is increased by 2kV / s.

[0129] A voltage is applied until the interface breaks down, and the breakdown voltage is recorded. The withstand voltage per unit length of the interface is calculated. After the voltage is applied, an electric field is formed between the first semiconducting tube 2011 and the second semiconducting tube 2012. Since the spacing between the insulating surfaces of the first semiconducting tube 2011 and the second semiconducting tube 2012 is very small, the electric field on the composite interface between the external insulation 2013 and the replaceable cable sample 202 is approximately uniformly distributed. Therefore, the interface breakdown field strength can be calculated using the following formula, thereby determining the electrical characteristics of the cable accessory interface under the combined influence of different temperatures, interface pressures, and surface roughness.

[0130]

[0131] Where U is the breakdown voltage, D is the distance between the high-voltage electrode and the low-voltage electrode, and E is the interface breakdown field strength.

[0132] External insulation 2013, first semiconducting tube 2011 and second semiconducting tube 2012 are spaced and sleeved on the outer wall of replaceable cable sample 202.

[0133] In the above scheme, the operating range of temperature adjustment can be 20℃~90℃, with an interval of 10℃~20℃. For example, the temperature can be 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 20℃, 40℃, 60℃, 80℃, and so on.

[0134] The interface pressure can be changed by replacing the replaceable cable sample 202 with one of different diameters to alter the interface pressure between the replaceable cable sample 202 and the accessory sample 201. For example, the pressure between the replaceable cable sample 202 and the accessory sample 201 can be set to 0.1 MPa, 0.3 MPa, 0.5 MPa, etc. The pressure between the two can be obtained by measuring the pressure sensor.

[0135] Surface roughness can be used to prepare replaceable cable samples 202 with different surface roughnesses, such as 0.2μm, 0.5μm, 1.0μm, and 2.0μm.

[0136] Orthogonal experimental design: using L934 or L164 3 Orthogonal arrays reduce the number of experiments and cover all combinations of variables.

[0137] Measure and record physical parameters and breakdown voltage to obtain test data;

[0138] An analytical model was established based on the test data to analyze the impact of physical parameters on the breakdown of composite interfaces in cable accessories.

[0139] In some alternative embodiments, when analyzing the effect of a single variable on interface breakdown, the remaining parameters in the physical parameters can be fixed, the effect of one physical parameter on dielectric strength can be studied, a physical parameter-breakdown voltage curve can be plotted, and the effect of each physical parameter on dielectric strength can be analyzed through this curve.

[0140] In some alternative embodiments, when analyzing the impact of multivariate interactions on interface breakdown, a quadratic polynomial model can be established, and the optimal combination of physical parameters can be obtained through visualization analysis.

[0141] This application achieves a comprehensive simulation of the coupling effects of multiple physical factors: First, by fitting the accessory sample 201 onto replaceable cable samples 202 with different diameters and surface roughnesses, the influence of interfacial contact states under different interfacial pressures and surface morphologies on the interfacial electrical properties is simulated. This design can more realistically reflect the diversity of interfacial pressure distribution in actual operation and its impact on electrical performance. Second, by simulating different temperature conditions and controlling temperature changes, this application studies the law of elasticity of cable rubber insulation components changing with temperature, and then analyzes its influence on interfacial pressure and electrical performance.

[0142] Through the above improvements, this application can more realistically simulate the coupling effect of multiple physical factors such as temperature field, interface pressure distribution and surface morphology characteristics in actual operating conditions, and fully reveal their influence mechanism on interface electrical properties, providing important theoretical basis and technical support for the design, optimization and operation and maintenance of cable joints.

[0143] Furthermore, the roughness is adjusted by replacing the replaceable cable sample 202 with different roughnesses. In this application, the roughness between the 360° circumferential contact interface between the actual cable insulation and the additional rubber insulation is simulated by roughening the surface of the replaceable cable sample 202. For example, the surface roughness treatment of the replaceable cable sample 202 can be performed by mechanical processing, such as sandpaper grinding or sandblasting, with a roughness range of 0.1-2 μm.

[0144] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0145] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A device for testing the electrical properties of a composite interface of a cable accessory, characterized in that, The utility model relates to an insulation test device, including: An insulation cylinder (300) is a hollow structure, the upper end of the insulation cylinder (300) is equipped with an upper gland (301), a high voltage electrode (302) is installed on the upper gland (301), the lower end of the insulation cylinder (300) is correspondingly provided with a lower gland (303), a low voltage electrode (304) is installed on the lower gland (303); A test plug structure (100) is installed on the inner wall of the upper gland (301) and the inner wall of the lower gland (303) respectively; An insulation sample (200) is a ring three-dimensional contact structure, and the insulation sample (200) is detachably installed in the test plug structure (100); A control circuit module (500) is electrically connected with the high voltage electrode (302) and the low voltage electrode (304) respectively, and is used for testing the voltage applied to the insulation sample (200); The insulation sample (200) includes an accessory sample (201) and a replaceable cable sample (202), the two ends of the replaceable cable sample (202) abut against the test plug structure (100), The accessory sample (201) is sleeved on the outer wall of the replaceable cable sample (202), and the accessory sample (201) and the replaceable cable sample (202) are in interference fit, and the replaceable cable sample (202) is used for changing the interface pressure between the accessory sample (201).

2. The test device of claim 1, wherein, The two ends of the replaceable cable sample (202) are conical.

3. The test device of claim 1, wherein, The accessory sample (201) includes a first semiconductive tube (2011), a second semiconductive tube (2012) and an additional insulation (2013), the first semiconductive tube (2011) and the second semiconductive tube (2012) are sleeved on the outer wall of the replaceable cable sample (202) at intervals, the additional insulation (2013) is sleeved on the outer wall of the first semiconductive tube (2011) and the outer wall of the second semiconductive tube (2012), and the additional insulation (2013) is integrally formed with the first semiconductive tube (2011) and the second semiconductive tube (2012).

4. The test device of claim 3, wherein, The middle position of the surface of the additional insulation (2013) is a toric surface (20131), the surfaces located on both sides of the toric surface (20131) are circular arc surfaces (20132) in transition from the toric surface (20131) to the end of the additional insulation (2013).

5. The test device of claim 3, wherein, In the radial direction, the opposite end structures of the first semiconductive tube (2011) and the second semiconductive tube (2012) are the same and both include a flat part (20111) and a circular arc part (20112), the flat part (20111) is located between the circular arc part (20112) and the replaceable cable sample (202), wherein, in the axial direction, the top of the flat part (20111) is lower than the top of the circular arc part (20112).

6. The test device of claim 1, wherein, The lower cover (303) has a containing cavity (3031) therein, and a heating assembly (600) is arranged in the containing cavity (3031).

7. The test device of claim 1, wherein, The test plug structure (100) comprises: a mounting base (10); a sleeve assembly (20) mounted on the mounting base (10) and movable along the axial direction of the mounting base (10); a plurality of support arms (30) arranged at intervals along the circumference of the sleeve assembly (20), wherein each support arm (30) comprises a rotating end (31) and a clamping end (32), and the rotating end (31) of each support arm (30) is rotatably connected to the mounting base (10); a support joint (40) arranged between each support arm (30) and the sleeve assembly (20), one end of the support joint (40) being rotatably connected to the support arm (30) and the other end being rotatably connected to the sleeve assembly (20); when the sleeve assembly (20) moves, the support joint (40) is driven to rotate, and the support joint (40) drives the clamping ends (32) of the plurality of support arms (30) to move towards each other, so as to clamp the insulation sample (200).

8. A method of testing the electrical properties of a cable accessory composite interface using a device for testing the electrical properties of a cable accessory composite interface as claimed in any one of claims 1 to 7, characterised in that, The method comprises the following steps: filling the insulation cylinder (300) with silicone oil so that the insulation sample (200) is immersed in the silicone oil; adjusting at least one physical parameter by the test device, the physical parameter comprising interfacial pressure, roughness, and temperature; wherein the interfacial pressure is adjusted by replacing the part of the insulation sample (200) with different diameters; measuring and recording the physical parameter and the breakdown voltage after adjustment to obtain test data; establishing an analysis model according to the test data to analyze the influence of the physical parameter on the breakdown of the composite interface of the cable accessory.

9. The test method of claim 8, wherein, The roughness is adjusted by replacing the part of the insulation sample (200) with different roughness.

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