Device and method for testing electrical characteristics of composite interface of cable accessory

Abstract

The invention is suitable for the technical field of testing, and provides a device and method for testing the electrical characteristics of a composite interface of a cable accessory, and the device comprises an insulating cylinder which is of a hollow structure, and the upper end of the insulating cylinder is provided with an upper gland and a high-voltage electrode; the lower end of the insulating cylinder is correspondingly provided with a lower gland and a low-voltage electrode; the test plugging structures are respectively arranged on the inner wall of the upper gland and the inner wall of the lower gland; the insulation sample is of an annular three-dimensional contact structure and is detachably mounted in the test plugging structure; and the control circuit module is electrically connected with the high-voltage electrode and the low-voltage electrode and is used for applying voltage to the insulation sample for testing. According to the testing device, 360-degree circumferential contact between real simulation cable insulation and additional rubber insulation is simulated more truly, and it is ensured that the source of interface pressure is consistent with the actual working condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage and insulation material interface breakdown characteristic testing, in particular to a device and method for testing the electrical characteristics of a composite interface of a cable accessory. BACKGROUND

[0002] In the prior art, the use of cable insulation power cables is increasing. A large amount of field operation experience shows that the interface between the cable insulation and the joint insulation at the connection between the cable accessory and the cable is most prone to breakdown.

[0003] There are many devices in the prior art for testing the electrical characteristics of the composite interface of a cable accessory, which are used to measure and study the mechanism of breakdown voltage occurrence, so as to improve the reliability of the cable system operation. However, the current testing device has the following technical problems: 1. The flat plate test piece model is usually used in the prior art, and the pressure is mainly derived from the different pressures applied by external devices to the flat plate test piece model, which cannot truly simulate the formation mechanism of the interface pressure in actual operation, resulting in a large deviation between the test results and the actual working conditions.

[0004] 2. The elasticity of the cable insulation is closely related to the elastic modulus, hardness, tensile strength and other parameters of the material, but these parameters change with temperature. In the actual operation process, the change of temperature will cause the corresponding change of the elasticity of the cable insulation, thereby affecting the interface pressure between the cable insulation and the cable accessory joint, and finally significantly affecting the electrical performance of the interface.

[0005] 3. The shape of the high-voltage electrode and the low-voltage electrode in the flat plate test piece model in the prior art is a thin sheet, and there will be electric field distortion at the edge, resulting in inaccurate test data.

[0006] 4. In the prior art, in order to test the electrical characteristics between the composite interface of the cable accessory and the cable insulation, the corresponding insulation test samples of the cable accessory and the cable insulation are usually made, and then a fixing device is used to fix the insulation test sample. In the current fixing device, some use multiple organic glass panels to place the insulation test sample between the adjacent two organic glass panels, and use bolts to fix the two organic glass panels, and some use multiple insulation rods to clamp and fix the insulation test sample. However, the current fixing device usually adjusts the bolts manually to clamp the insulation test sample, which may cause the insulation test sample to be clamped too tightly or too loosely, resulting in inaccurate electrical characteristic test results, and the insulation test sample is inconvenient to install and disassemble, and after multiple tests, the insulation test sample may be damaged or worn out. SUMMARY

[0007] The purpose of the present application is to provide a cable accessory composite interface electrical property testing device and method to solve the above technical problems in the prior art, mainly including the following contents: The first aspect of the present application provides a cable accessory composite interface electrical property testing device, comprising: An insulating cylinder, which is a hollow structure, is provided with an upper gland at its upper end, a high-voltage electrode is installed on the upper gland, a lower gland is correspondingly provided at the lower end of the insulating cylinder, and a low-voltage electrode is installed on the lower gland; A test plug structure is installed on the inner wall of the upper gland and the inner wall of the lower gland, respectively; An insulation sample, which is a ring-shaped three-dimensional contact structure, is detachably installed in the test plug structure; A control circuit module is electrically connected to the high-voltage electrode and the low-voltage electrode, respectively, for testing the voltage applied to the insulation sample.

[0008] Further, in order to better achieve the present application, the following setting structure is particularly adopted: the insulation sample includes an accessory sample and a replaceable cable sample, the two ends of the replaceable cable sample abut against the test plug structure, The accessory sample is sleeved on the outer wall of the replaceable cable sample, and the accessory sample and the replaceable cable sample are in interference fit, and the replaceable cable sample is used to change the interface pressure between the accessory sample.

[0009] Further, in order to better achieve the present application, the following setting structure is particularly adopted: the two ends of the replaceable cable sample are conical.

[0010] Further, in order to better achieve the present application, the following setting structure is particularly adopted: the accessory sample includes a first semi-conductive tube, a second semi-conductive tube, and an additional insulation, the first semi-conductive tube and the second semi-conductive tube are spaced apart and sleeved on the outer wall of the replaceable cable sample, the additional insulation is sleeved on the outer wall of the first semi-conductive tube and the second semi-conductive tube, and the additional insulation is integrally formed with the first semi-conductive tube and the second semi-conductive tube.

[0011] Further, in order to better achieve the present application, the following setting structure is particularly adopted: the middle position of the surface of the additional insulation is a circular ring surface, the surfaces located on both sides of the circular ring surface are circular arc surfaces that transition from the circular ring surface to the end of the additional insulation.

[0012] Further, in order to better realize the application, the following arrangement is adopted: the opposite end structures of the first semi-conductive tube and the second semi-conductive tube are the same in the radial direction, and each comprises a flat part and a circular arc part, and the flat part is located between the circular arc part and the replaceable cable sample, wherein, in the axial direction, the top of the flat part is lower than the top of the circular arc part.

[0013] Further, in order to better realize the application, the following arrangement is adopted: the lower pressing cover has a containing cavity, and the containing cavity is provided with a heating assembly.

[0014] Further, in order to better realize the application, the following arrangement is adopted: the test plug structure comprises: a mounting seat; a sleeve assembly, which is mounted on the mounting seat and can move along the axial direction of the mounting seat; a plurality of support arms, which are arranged at intervals in the circumferential direction of the sleeve assembly, wherein the support arm comprises a rotating end and a clamping end, and the support arm is rotatably connected to the mounting seat through the rotating end; a support joint, which is arranged between the support arm and the sleeve assembly, and one end of the support joint is rotatably connected to the support arm, and the other end is rotatably connected to the sleeve assembly; When the sleeve assembly moves, the support joint is driven to rotate, and the support joint drives the clamping ends of the plurality of support arms to move close to each other, so as to clamp the insulation sample.

[0015] The second aspect of the application provides a test method for the electrical characteristics of a cable accessory composite interface, which adopts the test device for the electrical characteristics of a cable accessory composite interface, and comprises the following steps: filling the insulating cylinder with silicone oil so that the insulation sample is immersed in the silicone oil; adjusting at least one physical parameter through the test device, wherein the physical parameter comprises 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 different diameters; measuring and recording the physical parameters and breakdown voltage after adjustment to obtain test data; establishing an analysis model according to the test data, and analyzing the influence of the physical parameters on the breakdown of the cable accessory composite interface.

[0016] Further, the roughness is adjusted by replacing the replaceable cable sample with different roughness.

[0017] The application has at least the following technical effects relative to the prior art: 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.

[0018] 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

[0019] 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.

[0020] Figure 1 This is a schematic diagram of the test apparatus in this application; Figure 2 This is a three-dimensional structural diagram of the insulating cylinder in this application; Figure 3 Top view of the insulating cylinder in this application; Figure 4 yes Figure 3 Cross-sectional view along the AA direction; Figure 5 This is a three-dimensional structural schematic diagram of the insulating sample in this application; Figure 6 yes Figure 5 Cross-sectional view along the BB direction; Figure 7 This is a three-dimensional structural schematic diagram of the replaceable cable sample in this application; Figure 8 This is a frontal view of the specimen attached to this application; Figure 9 is Figure 8 a sectional view along the direction of C-C in the figure; Figure 10 is Figure 9 a partial enlarged view of the F part in the figure; Figure 11 is a three-dimensional schematic view of the accessory sample in the present application; Figure 12 is a three-dimensional structural schematic view of the test plug-in structure in the present application; Figure 13 is a top view of the test plug-in structure in the present application; Figure 14 is Figure 13 a sectional view along the direction of G-G in the figure; Figure 15 is a structural schematic view of the support frame in the present application; Figure 16 is a structural schematic view of the clamping unit in the present application; Figure 17 is a structural schematic view of the support joint in the present application.

[0021] in the figure: 1000, test device; 100, test plug-in structure; 10, mounting seat; 20, sleeve assembly; 21, sleeve; 211, support rod; 212, support piece; 2121, support cavity; 22, support frame; 221, connecting part; 23, contraction piece; 30, support arm; 31, rotating end; 32, clamping end; 33, clamping piece; 331, clamping unit; 3311, containing groove; 3312, clamping part; 3313, limiting part; 34, clamping cavity; 35, bending part; 40, support joint; 41, rotating groove; 42, limiting groove; 200, insulation sample; 201, accessory sample; 2011, first semi-conductive tube; 20111, planar part; 20112, circular arc part; 2012, second semi-conductive tube; 2013, additional insulation; 20131, toric surface; 20132, circular arc surface; 202, replaceable cable sample; 300, insulation cylinder; 301, upper pressure cover; 302, high-voltage electrode; 303, lower pressure cover; 3031, containing cavity; 304, low-voltage electrode; 500, control circuit module; 600, heating assembly. DETAILED DESCRIPTION

[0022] The following description provides many different embodiments, or examples, for implementing different features of the application. Specific examples are described in the following to provide a thorough description of embodiments of the application. These examples are not intended to be limiting. Consequently, the application is not limited to the specific examples described.

[0023] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, any other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application.

[0024] In the present application, unless specifically defined and limited otherwise, the terms "mount", "connect", "connection", "fixed", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0025] In the present application, unless specifically defined and limited otherwise, the first feature above or below the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature above, above and above the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher than the second feature in horizontal height. The first feature below, below and below the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower than the second feature in horizontal height.

[0026] There are many devices for testing the electrical properties of the composite interface of cable accessories in the prior art, which are used to measure and study the mechanism of breakdown voltage occurrence, so as to improve the reliability of the operation of the cable system. However, the current testing device has the following technical problems: 1. In actual working conditions, the cable insulation and the cable accessory joint are in 360° circumferential three-dimensional contact, and the pressure between the cable insulation and the cable accessory joint is mainly derived from the elastic force of the cable accessory joint itself after the interference fit between the cable insulation and the cable accessory joint. However, the existing technology usually adopts a flat sheet model, and the pressure is mainly derived from the different pressure applied by an external device to the flat sheet model, which cannot truly simulate the formation mechanism of the interface pressure in actual operation, resulting in a large deviation between the test results and the actual working conditions.

[0027] 2. The elastic force of the cable insulation is closely related to the elastic modulus, hardness, tensile strength and other parameters of the material of the cable insulation, but these parameters change with temperature. In the actual operation process, the change of temperature will cause the corresponding change of the elastic force of the cable insulation, thereby affecting the interface pressure between the cable insulation and the cable accessory joint, and finally having a significant impact on the electrical performance of the interface.

[0028] 3. The high-voltage electrode and the low-voltage electrode in the flat sheet model adopted in the existing technology are in the shape of a sheet, and there will be electric field distortion at the edge thereof, resulting in unrealistic test data.

[0029] 4. The design of the cable accessory relies on empirical formula, and lacks quantitative analysis of the influence of the interface micro-morphology (such as the roughness of the rubber surface), resulting in unsatisfactory partial discharge suppression effect.

[0030] 5. In the existing technology, in order to test the electrical characteristics of the composite interface between the cable accessory joint and the cable insulation, an insulation sample corresponding to the cable accessory joint and the cable insulation is usually first made, and then a fixing device is used to fix the insulation sample. In the current fixing device, some use multiple organic glass panels to place the insulation test sample between the adjacent two layers of organic glass panels, and use bolts to fix the two layers of organic glass. Others use multiple insulation rods to clamp and fix the insulation sample. However, the existing fixing device usually adjusts the bolts manually to clamp the insulation sample, which may cause the insulation sample to be clamped too tightly or too loosely, resulting in inaccurate electrical characteristic test results. Moreover, the installation and disassembly of the insulation sample are not convenient, and after multiple tests, the insulation test sample may be damaged or worn out.

[0031] Therefore, the present application provides a test device and method for the electrical characteristics of the composite interface of the cable accessory to solve the above technical problems in the existing technology, mainly including the following contents: Embodiment one The embodiment one of the present application provides a test device for the electrical characteristics of the composite interface of the cable accessory, as shown in Figures 1-17 The test device comprises: The insulating barrel 300 is in a whole cylindrical shape and has a hollow structure. The main body of the insulating barrel 300 is made of epoxy glass fiber. The outer wall of the insulating barrel 300 is arranged in the vertical direction and alternately provided with umbrella skirts of different lengths. The umbrella skirts are made of silica gel material and can eliminate the interference of external environmental factors on the test results. The upper end of the insulating barrel 300 is provided with an upper pressing cover 301. The upper pressing cover 301 is in a disc shape and is detachably connected to the upper end of the insulating barrel 300 in a sealed manner. The upper pressing cover 301 is made of transparent material, such as acrylic plate, and can be used to observe the state of the insulating sample 200 in the insulating barrel 300 in real time. The upper pressing cover 301 is provided with a high-voltage electrode 302 for providing a high-voltage end required in a test circuit. The lower end of the insulating barrel 300 is provided with a lower pressing cover 303 corresponding thereto. The lower pressing cover 303 is in a disc shape and is made of high-temperature-resistant material, such as ceramic glass or microcrystalline glass. The lower pressing cover 303 is provided with a low-voltage electrode 304 for providing a grounding end required in the test circuit. In the present application, the upper pressing cover 301 and the lower pressing cover 303 are designed in a disc shape, so that the edge electric field is uniformly distributed and the risk of sample breakdown caused by local electric field concentration is avoided.

[0032] The test plug structure 100 is mounted on the inner wall of the upper pressing cover 301 and the inner wall of the lower pressing cover 303. Exemplarily, two test plug structures 100 are mounted in the insulating barrel 300. Each test plug structure 100 includes a connecting end and a clamping end. The connecting end of one test plug structure 100 is detachably connected to the inner wall of the upper pressing cover 301, and the clamping end is used to clamp one end of the insulating sample 200. The connecting end of the other test plug structure 100 is detachably connected to the inner wall of the lower pressing cover 303, and the clamping end is used to clamp the other end of the insulating sample 200. The two test plug structures 100 and the insulating sample 200 are coaxially arranged, so as to avoid the insulating sample 200 being affected by other external forces and affecting the correctness of the test results.

[0033] The insulating sample 200 is in a ring-shaped three-dimensional contact structure. The ring-shaped three-dimensional contact structure is used to replace the flat plate test piece model, to truly simulate the 360° circumferential contact between the cable insulation and the additional rubber insulation, and to ensure that the source of the interface pressure is consistent with the actual working condition. The insulating sample 200 is detachably mounted in the test plug structure 100. Exemplarily, the clamping end 32 of the test plug structure 100 is initially in an open state. First, one end of the insulating sample 200 is placed in the sleeve seat assembly 20 of the test plug structure 100 connected to the lower pressing cover 303, and then the upper pressing cover 301 is covered. The two ends of the insulating sample 200 press against the sleeve seat assembly 20. The sleeve seat assembly 20 drives the support joint 40 to rotate, and then drives the clamping end 32 to approach each other, so as to clamp the insulating sample 200.

[0034] The test plug structure 100 in the application is a reusable mechanical plug structure. The test plug structure 100 not only facilitates the quick assembly and disassembly of the insulation test sample 200, but also significantly improves the test efficiency, reduces the model loss caused by frequent replacement of the insulation test sample 200, prolongs the service life of the test device, and provides a more scientific, accurate and efficient solution for the test of the electrical properties of the cable accessory composite interface, which has important engineering application value.

[0035] The control circuit module 500 is electrically connected with the high-voltage electrode 302 and the low-voltage electrode 304 respectively, and is used for applying voltage to the insulation test sample 200 for testing. For example, the control circuit module 500 adopts an insulation material withstand voltage test device. The device is supplied with a test voltage obtained by a booster transformer through a variable low-voltage sinusoidal power supply. The voltage is controlled by a computer, and the boosting speed is uniform and stable. The secondary rated current of the high-voltage transformer is not less than 0.1A, which ensures that the device is not burned out at the moment of breakdown. The voltage regulator should be able to uniformly regulate the voltage, and its capacity should be the same as that of the test transformer. The voltage measurement should be carried out at the high-voltage end by using a high-voltage static voltmeter with a level not greater than 2.5, or by using a voltage divider to measure, with an error of less than ±4%. The control circuit is as shown in Figure 1 , wherein K1 is a power switch, T1 is a voltage regulator transformer, V is a voltmeter, T2 is a high-voltage transformer, and K2 is an overcurrent relay.

[0036] Therefore, the test device for the electrical properties of the cable accessory composite interface provided by the application comprises: an insulation cylinder 300, the insulation cylinder 300 comprising an upper pressure cover 301 and a lower pressure cover 303, a test plug structure 100 being mounted on the inner wall of the upper pressure cover 301 and the inner wall of the lower pressure cover 303 respectively, an insulation test sample 200, the insulation test sample 200 being a ring-shaped three-dimensional contact structure and being detachably mounted in the test plug structure 100, and a control circuit module 500, the control circuit module 500 being electrically connected with a high-voltage electrode 302 and a low-voltage electrode 304 respectively and being used for applying voltage to the insulation test sample 200 for testing. The insulation test sample 200 in the application is a ring-shaped three-dimensional contact structure, which replaces the flat plate test piece model to truly simulate the 360° circumferential contact between the cable insulation and the additional rubber insulation, ensures that the source of the interface pressure is consistent with the actual working condition, and the test plug structure 100 not only facilitates the quick assembly and disassembly of the insulation test sample 200, but also significantly improves the test efficiency, reduces the model loss caused by frequent replacement of the insulation test sample 200, and prolongs the service life of the test device.

[0037] According to some optional embodiments, the insulation sample 200 comprises an accessory sample 201 and a replaceable cable sample 202, the accessory sample 201 is a sample of a cable accessory joint, and the replaceable cable sample 202 is a sample of cable insulation, and the two ends of the replaceable cable sample 202 abut against the sleeve 21 in the test plug structure 100.

[0038] 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 to change the interface pressure between the accessory sample 201.

[0039] In some optional embodiments, the replaceable cable sample 202 is cylindrical, and the accessory sample 201 is also cylindrical as a whole, and the accessory sample 201 is sleeved on the outer wall of the replaceable cable sample 202 in interference fit to form an annular three-dimensional contact structure. The annular three-dimensional contact model is used to replace the flat plate sample model to truly simulate the 360° circumferential contact between the cable insulation and the additional rubber insulation, and to ensure that the source of the interface pressure is consistent with the actual working condition.

[0040] For example, the length of the replaceable cable sample 202 is 220 mm, and the diameter of the outer diameter ranges from 36 mm to 44 mm. Different interference fit requirements between the replaceable cable sample 202 and the accessory sample 201 are achieved by manufacturing a plurality of replaceable cable samples 202 with different diameters, that is, different interface pressures between the replaceable cable sample 202 and the accessory sample 201 need to be simulated. In this application, the accessory sample 201 does not need to be replaced, and only the replaceable cable sample 202 with different diameters needs to be replaced to truly simulate the different pressures between the cable insulation and the cable accessory joint, so that the test data is consistent with the actual working condition.

[0041] According to some optional embodiments, the two ends of the replaceable cable sample 202 are smooth and tapered, that is, the diameter of the replaceable cable sample 202 gradually decreases along the end portion, so that the accessory sample 201 is easily sleeved on the outer wall of the replaceable cable sample 202 along the taper of any one end of the replaceable cable sample 202, avoiding damage to the inner wall of the accessory sample 201 by the end portion of the replaceable cable sample 202.

[0042] According to some optional embodiments, the accessory sample 201 comprises a first semi-conductive tube 2011, a second semi-conductive tube 2012 and an additional insulation 2013, the first semi-conductive tube 2011 and the second semi-conductive tube 2012 are coaxially sleeved on the outer wall of the replaceable cable sample 202. For example, the first semi-conductive tube 2011 and the second semi-conductive tube 2012 are cylindrical, and the interval distance between the first semi-conductive tube 2011 and the second semi-conductive tube 2012 is 10.0±0.1mm, which meets the requirements of insulation strength test specified in GB / T 1408.1 and facilitates the accurate calculation of interface dielectric parameters. The additional insulation 2013 is sleeved on the outer wall of the first semi-conductive tube 2011 and the outer wall of the second semi-conductive tube 2012, and the additional insulation 2013 is integrally formed with the first semi-conductive tube 2011 and the second semi-conductive tube 2012. For example, the additional insulation 2013 wraps the opposite ends of the first semi-conductive tube 2011 and the second semi-conductive tube 2012 in the inner wall, and the other ends of the first semi-conductive tube 2011 and the second semi-conductive tube 2012 exceed the two ends of the additional insulation 2013, and the test plug structure 100 can hold the two ends of the first semi-conductive tube 2011 and the second semi-conductive tube 2012 which exceed the additional insulation 2013, so as to realize the communication of the first semi-conductive tube 2011 and the second semi-conductive tube 2012 with the high-voltage electrode 302 and the low-voltage electrode 304 respectively.

[0043] In the above scheme, the preparation of the accessory sample 201 adopts a composite injection rubber molding process, and a split mold design scheme is adopted, that is, a special molding mold for semi-conductive tubes and a whole accessory sample molding mold are designed respectively. Specifically, first, the insulation rubber is injected into the special molding mold for semi-conductive tubes to complete the preparation of the first semi-conductive tube 2011 and the second semi-conductive tube 2012, then the first semi-conductive tube 2011 and the second semi-conductive tube 2012 are placed and assembled in the whole accessory sample molding mold, the coaxial placement of the whole accessory sample molding mold, the first semi-conductive tube 2011 and the second semi-conductive tube 2012 is ensured through the positioning pin system, then the additional insulation 2013 is formed by twice injection of cross-linked polyethylene material, and after the additional insulation 2013 is cured, the integrated accessory sample 201 with no gap is formed, which perfectly matches the first semi-conductive tube 2011 and the second semi-conductive tube 2012. This accessory sample 201 with insulation structure ensures that the electric field strength is uniform and continuous from the cable body to the joint inside, which greatly reduces the risk of partial discharge, which is the main reason for insulation deterioration and final breakdown.

[0044] According to some optional embodiments, the middle position of the surface of the external insulation 2013 is a torus surface 20131, the surfaces on both sides of the torus surface 20131 are transitioned to the end of the external insulation 2013 along the torus surface 20131 as a circular arc surface 20132. Exemplarily, the circular arc surface 20132 is concave towards the replaceable cable sample 202. The diameter of the circular arc surface 20132 is 110 mm, and by such setting, the creepage distance is increased, the flashover phenomenon caused by external factors such as contamination and moisture is greatly reduced, external interference is maximally excluded, the surface discharge phenomenon is effectively inhibited, and the test result is more accurate and reliable.

[0045] According to some optional embodiments, along the radial direction, the opposite end structures of the first semiconductive tube 2011 and the second semiconductive tube 2012 are the same, and each includes a flat portion 20111 and a circular arc portion 20112. The flat portion 20111 is located between the circular arc portion 20112 and the replaceable cable sample 202, and the flat portion 20111 is connected with the circular arc portion 20112, and a step is formed at the connection position of the two. Along the axial direction, the top of the flat portion 20111 is lower than the top of the circular arc portion 20112, that is, the circular 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 circular arc portion 20112 and the flat portion 20111, so that the stability of the accessory sample 201 is enhanced, and the tensile strength is increased.

[0046] In some optional embodiments, the radial dimension d of the flat portion 20111 is 1-1.5 mm, which facilitates the injection molding of the external rubber.

[0047] In some optional embodiments, along the radial direction, the size of the flat portion 20111 is smaller than the diameter of the circular arc portion 20112. In this way, the external insulation 2013 is firmly formed with the first semiconductive tube 2011 and the second semiconductive tube 2012.

[0048] In some optional embodiments, the plane of the flat portion 20111 is coplanar with the diameter of the circular arc portion 20112, which facilitates processing and glue injection.

[0049] According to some optional embodiments, the lower pressing cover 303 has a containing cavity 3031, and the containing cavity 3031 is provided with a heating assembly 600.

[0050] In the above scheme, the heating assembly 600 can include a heating wire and a switch piece. The heating wire and the switch piece are electrically connected. The heating wire is fixedly installed in the containing cavity 3031, and the switch piece is installed on the side wall of the lower pressing cover 303. When the test is performed, the heating temperature of the heating wire is controlled through the switch piece, so as to heat the silicone oil in the insulation cylinder 300. The temperature range of the heated silicone oil is 20-90℃.

[0051] According to some optional embodiments, the test plug structure 100 comprises: A mounting seat 10, the mounting seat 10 is used for detachably mounting the test plug structure 100 in a test device 1000 for testing electrical characteristics of a cable accessory composite interface, and the test plug structure 100 clamps an insulation test sample 200 in the test device 1000. For example, the mounting seat 10 can be detachably mounted in the test device 1000 by a bolt structure.

[0052] In some optional embodiments, the mounting seat 10 can be provided as a mounting plate structure, and the mounting seat 10 can be provided as a square, a rectangle, etc., which is not limited herein. In this application, the mounting seat 10 is provided as a circle to adapt to the shape of the test device 1000.

[0053] A sleeve assembly 20, the sleeve assembly 20 is mounted on the mounting seat 10, and the sleeve assembly 20 is movable along the axial direction of the mounting seat 10.

[0054] For example, one end of the sleeve assembly 20 is connected to the mounting seat 10 by a contraction member 23, and the other end is a free end, which has a cavity capable of accommodating an end portion of the insulation test sample 200. The end portion of the insulation test sample 200 can be mounted in the free end of the sleeve assembly 20, and a downward force is applied to the sleeve assembly 20 during the mounting of the insulation test sample 200. Under the action of the force, the sleeve assembly 20 moves towards the mounting seat 10. After the insulation test sample 200 is dismounted, the sleeve assembly 20 moves away from the mounting seat 10 under the action of the contraction member 23 and returns to the initial state. In this application, the diameter of the sleeve assembly 20 is greater than or equal to the maximum diameter of the end portion of the insulation test sample 200 of different specifications, so that the sleeve assembly 20 can be used to accommodate insulation test samples of different specifications, and the application range is wide.

[0055] A plurality of support arms 30 are arranged at intervals along the circumference of the sleeve assembly 20, i.e. the plurality of support arms 30 are arranged around the four sides of the sleeve assembly 20, so that the sleeve assembly 20 is located in the space defined by the plurality of support arms 30, and the insulation test sample 200 can smoothly enter the sleeve assembly 20 through the space defined by the plurality of support arms 30. The support arm 30 comprises a rotating end 31 and a clamping end 32, and the support arm 30 is rotatably connected to the mounting seat 10 by the rotating end 31. For example, a rotating member is mounted on the mounting seat 10, and the rotating end 31 of the support arm 30 is rotatably connected to the rotating member by a pin shaft. The clamping end 32 of the support arm 30 is a free end, which is away from the mounting seat 10 and located above the sleeve assembly 20, and is used for clamping the insulation test sample 200. In this application, the support arm 30 is provided as a plurality of support arms, which are close to each other to clamp the insulation test sample 200. The plurality of support arms 30 can clamp insulation test samples 200 of different specifications.

[0056] In some alternative embodiments, the number of support arms 30 is 2, 3, 4, etc. In the present application, the number of support arms 30 is preferably 3.

[0057] A support joint 40 is arranged 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 the lower position, and the other end is rotatably connected to the sleeve assembly 20 near the mounting base 10. The support joint 40 is arranged to be inclined towards the mounting base 10, which facilitates the movement of the sleeve assembly 20 to pull the support joint 40, thereby bringing the plurality of support arms 30 closer to each other to clamp the insulation test sample 200, and also avoids the situation that the support joint 40 is stuck during movement.

[0058] 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 closer to or away from each other, for clamping the insulation test sample 200. For example, when the test plug-in structure 100 is in the initial state, the sleeve assembly 20 is at a position away from the mounting base 10, and the plurality of support arms 30 are away from the sleeve assembly 20 in an open state. When it is necessary to clamp the insulation test sample 200, the end of the insulation test sample 200 enters the cavity at the end of the sleeve assembly 20 away from the mounting base 10, and the insulation test sample 200 exerts a downward force on the sleeve assembly 20. Under the action of the force, the sleeve assembly 20 moves towards the mounting base 10, and at the same time drives the plurality of support joints 40 to move towards the mounting base 10. The plurality of support joints 40 drive the corresponding plurality of support arms 30 to move towards the sleeve assembly 20, and clamp the insulation test sample 200. The disassembly process of the insulation test sample 200 is opposite to the installation process, which will not be described here.

[0059] Therefore, the test plug structure 100 provided by the application is used for clamping the insulation test sample 200, and includes a mounting seat 10, a sleeve assembly 20, a plurality of support arms 30 and a plurality of support joints 40. The sleeve assembly 20 is arranged on the mounting seat 10, the plurality of support arms 30 are arranged in a circumferential direction of the sleeve assembly 20, and each support arm 30 is connected to the sleeve assembly 20 through a corresponding support joint 40. When the insulation test sample 200 needs to be clamped, the end of the insulation test sample 200 enters the cavity of the sleeve assembly 20, and the sleeve assembly 20 is moved towards the mounting seat 10, so that the plurality of support arms 30 are driven to move by driving the support joints 40 to move, thereby clamping the insulation test sample 200. The sleeve assembly 20 and the support arms 30 in the test plug structure 100 provided by the application can be used for clamping insulation test samples 200 of different specifications, without damaging the surface of the insulation test sample 200. In addition, the test plug structure 100 not only facilitates the quick assembly and disassembly of the insulation test sample 200, but also significantly improves the test efficiency, reduces the damage and loss of the insulation test sample 200 caused by frequent operation, prolongs the service life of the insulation test sample 200 and the test plug structure 100, provides a more scientific, accurate and efficient solution for the test of the electrical properties of the cable accessory composite interface, and avoids affecting the accuracy of the test results.

[0060] According to some optional embodiments, the sleeve assembly 20 is vertically arranged on the mounting seat 10 and coaxially arranged with the mounting seat 10. The sleeve assembly 20 includes a sleeve 21, a support frame 22 and a contraction member 23, and the support frame 22 is located between the sleeve 21 and the contraction member 23 and coaxially arranged with the sleeve 21 and the contraction member 23. The sleeve 21 is provided with a cavity for accommodating the end of the insulation test sample 200 away from the mounting seat 10.

[0061] One end of the contraction member 23 is fixedly connected to the mounting seat 10, and the other end is fixedly connected to the lower surface of the support frame 22. The contraction member 23 can be axially extended and retracted. The initial height of the contraction member 23 in the vertical direction is the movable stroke of the sleeve assembly 20 relative to the mounting seat 10. The upper surface of the support frame 22 is connected to the sleeve 21, and is used for providing a support force to the sleeve 21 to support the insulation test sample 200. The side wall of the support frame 22 is rotationally connected to one end of the support joint 40. When the sleeve 21 moves, the support frame 22 can drive the support joints 40 to move close to or 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, the side wall of the disc is provided with a plurality of connecting portions 221, each connecting portion 221 is arranged corresponding to the support joint 40, and when the support frame 22 moves in the axial direction, the plurality of support joints 40 can be driven to move in the axial direction at the same time, thereby driving the plurality of support arms 30 to move close to or away from each other.

[0062] According to some optional embodiments, a plurality of connecting portions 221 are arranged on the side wall of the support frame 22, and each connecting portion 221 is rotationally connected with each support joint 40.

[0063] In some optional embodiments, the number of the connecting portions 221 corresponds to the number of the support joints 40, and each connecting portion 221 is a connecting rod, one end of which is fixedly connected with the lower end of the sleeve 21, and the other end is rotationally connected with the end of the support joint 40. The connecting portion 221 is arranged in the horizontal direction, and the rotation space of the support joint 40 can be ensured by such arrangement of the connecting portion 221, so as to avoid interference with the sleeve 21 or the contraction member 23.

[0064] According to some optional embodiments, the contraction member 23 includes a first contraction member and a second contraction member. The first contraction member is fixedly connected with the mounting base 10, and has a contraction cavity in which an elastic member is arranged. One end of the second contraction member is inserted into the contraction cavity and connected with the elastic member, and the other end of the second contraction member is connected with the lower surface of the support frame 22. For example, the first contraction member and the second contraction member can both be tubular, and the elastic member can be a spring. The second contraction member moves up and down along the contraction cavity of the first contraction member, so as to realize the axial movement of the sleeve 21 and the automatic recovery of the sleeve 21 to the initial state.

[0065] In some optional embodiments, the contraction member 23 can be a spring.

[0066] According to some optional embodiments, the clamping end 32 of the support arm 30 is provided with a clamping unit 331, and the clamping unit 331 has a receiving groove 3311. When a plurality of support arms 30 are close to each other, a plurality of clamping units 331 are spliced to form a clamping member 33, and a plurality of receiving grooves 3311 form a clamping cavity 34 of the clamping member 33. The insulation test sample 200 passes through the clamping cavity 34 and is clamped by the clamping member 33. The clamping member 33 formed by splicing a plurality of clamping units 331, and the clamping cavity 34 formed by a plurality of receiving grooves 3311 can clamp insulation test samples 200 of different specifications, and has a wide range of applications.

[0067] In the above scheme, a plurality of clamping units 331 are abutted and spliced together to form a clamping member 33, and the clamping member 33 and the clamping cavity 34 are circular. In some optional embodiments, the shape of the clamping member 33 and the clamping cavity 34 matches the shape of the outer wall of the clamping position of the insulation test sample 200.

[0068] According to some optional embodiments, the clamping unit 331 comprises a clamping portion 3312 and a limiting portion 3313, the outer wall of the clamping portion 3312 is fixedly connected with the clamping end 32, and the lower end of the clamping portion 3312 is connected with the limiting portion 3313 perpendicularly to define a containing groove 3311. The lower end of the clamping portion 3312 is connected with the limiting portion 3313 perpendicularly to form a limiting step.

[0069] In the above scheme, the clamping portion 3312 has a ring structure, which is suitable for the outer wall shape of the insulation sample 200. The limiting portion 3313 can abut against the protruding portion on the outer wall of the insulation sample 200, so as to avoid that the force applied by the insulation sample 200 on the sleeve assembly 20 is too large, thereby causing the sleeve assembly 20 to be unable to recover to the initial state.

[0070] In some optional embodiments, the clamping portion 3312 and the limiting portion 3313 are integrally formed.

[0071] According to some optional embodiments, the sleeve 21 comprises a support rod 211 and a support piece 212, one end of the support rod 211 is connected with the upper surface of the support frame 22, the other end is fixedly connected with the support piece 212, the end of the support piece 212 away from the support rod 211 has an opening, the support piece 212 has a support cavity 2121, the support cavity 2121 is communicated with the clamping cavity 34, so that the insulation sample 200 can pass through the clamping cavity 34 to enter the support cavity 2121, so that the insulation sample 200 is subjected to the clamping force in the horizontal direction in the clamping cavity 34 and the supporting force in the vertical direction by the support cavity 2121, which together ensure the stability of the insulation sample 200 in the test device 1000 and ensure the smooth progress of the test.

[0072] In some optional embodiments, the support rod 211 and the support piece 212 can be detachably connected, or can be integrally formed, which is not limited herein.

[0073] According to some optional embodiments, one end of the support joint 40 is provided with a rotating groove 41, one end of the connecting portion 221 is inserted into the rotating groove 41, the other end of the support joint 40 is provided with a limiting groove 42, and the support arm 30 passes through the limiting groove 42 and can rotate relative to the limiting groove 42, which also limits the rotation range of the support arm 30, thereby avoiding the situation that the rotation is too large and cannot be reset.

[0074] In the above scheme, one end of the connecting portion 221 can be connected with the support joint 40 through a rotating shaft, and the end of the support joint 40 can also be connected with the support arm 30 through a rotating shaft.

[0075] According to some optional embodiments, the support arm 30 has a bending portion 35 connected with the support joint 40. The support arm 30 is in the shape of a less-than sign, and the setting of the bending portion 35 makes the clamping end 32 of the support arm 30 close to the sleeve assembly 20, so that the sleeve assembly 20 only needs to move a small distance in the axial direction to realize the clamping of the insulation sample 200 by the clamping units 331 of the plurality of clamping ends 32.

[0076] Embodiment two: The embodiment two of the application provides a test method for electrical characteristics of a cable accessory composite interface, using the test device for electrical characteristics of the cable accessory composite interface, and the method comprises the following steps: The insulation cylinder 300 is filled with silicone oil, so that the insulation sample 200 is immersed in the silicone oil. For example, high-performance silicone oil with a viscosity of 10000 can be used to ensure the accuracy of the test data.

[0077] The test device is used to adjust at least one physical parameter, and the physical parameter includes an interface pressure, a roughness and a temperature. The interface pressure between the replaceable cable sample 202 and the accessory sample 201 is adjusted by replacing the replaceable cable sample 202 with different diameters. The silicone oil in the insulation cylinder 300 is heated in an electric heating manner by a heating system, and the silicone oil is heated to a preset temperature and kept at the current temperature. The influence of the physical parameters such as the pressure and the roughness on the breakdown of the cable accessory composite interface at the preset temperature is studied. The control circuit module 500 is used to apply a voltage to the insulation sample 200 to simulate the influence of an electric field. When the breakdown voltage is less than 20 kV, the voltage is increased at a rate of lkV / s. When the breakdown voltage is greater than or equal to 20 kV, the voltage is increased at a rate of 2 kV / s.

[0078] The voltage is applied until the interface breaks down, and the breakdown voltage is recorded. The withstand voltage level of the unit length interface is calculated. An electric field is formed between the first semiconductive tube 2011 and the second semiconductive tube 2012 after the voltage is applied. Since the distance between the insulation surfaces of the first semiconductive tube 2011 and the second semiconductive 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 following formula can be used to calculate the interface breakdown field strength, so as to determine the electrical characteristics of the cable accessory interface under the combined influence of different temperatures, interface pressures and surface roughnesses.

[0079]

[0080] Wherein, 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.

[0081] The external insulation 2013, the first semiconductive tube 2011 and the second semiconductive tube 2012 are spacedly sleeved on the outer wall of the replaceable cable sample 202.

[0082] In the above scheme, the operating range of the temperature adjustment can be 20-90℃, with an interval of 10-20℃, such as the temperature can take values of 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or values of 20℃, 40℃, 60℃, 80℃, and so on.

[0083] The interface pressure value can be changed by replacing the replaceable cable sample 202 with different diameters to change the interface pressure between the accessory sample 201, such as the pressure between the replaceable cable sample 202 and the accessory sample 201 being set to 0.1 MPa, 0.3 MPa, 0.5 MPa, etc., and the pressure between the two can be measured by a pressure sensor.

[0084] The surface roughness can be prepared with replaceable cable samples 202 of different surface roughness, such as roughness can be set to 0.2 μm, 0.5 μm, 1.0 μm, 2.0 μm.

[0085] Orthogonal test design: L934 or L164 3 Orthogonal table, reducing the number of experiments and covering the full variable combination.

[0086] Measure and record physical parameters, breakdown voltage, and obtain test data; According to the test data, an analysis model is established to analyze the influence of physical parameters on the breakdown of the cable accessory composite interface.

[0087] In some optional embodiments, when analyzing the influence of single variable on interface breakdown, the remaining parameters in the physical parameters can be fixed to study the influence of one physical parameter on dielectric strength, and a physical parameter-breakdown voltage curve is drawn to analyze the influence of each physical parameter on dielectric strength.

[0088] In some optional embodiments, when analyzing the influence of multi-variable interaction on interface breakdown, a quadratic polynomial model can be established, and the optimal physical parameter combination is obtained through visual analysis.

[0089] The present application realizes comprehensive simulation of the coupling of multiple physical factors: first, by fitting the accessory sample 201 on replaceable cable samples 202 of different diameter specifications and different surface roughness, the influence of interface contact state under different interface pressures and different surface topographies on interface electrical properties is simulated. This design can more realistically reflect the diversity of interface pressure distribution in actual operation and its influence on electrical performance. Second, the present application simulates different temperature conditions by controlling temperature changes to study the law of cable rubber insulation piece elasticity changing with temperature, and further analyzes its influence on interface pressure and electrical performance.

[0090] Through the above improvements, the application can more truly simulate the coupling of multiple physical factors such as temperature field, interface pressure distribution and surface topography characteristics in actual operating conditions, and comprehensively reveal the influence mechanism of the multiple physical factors on the electrical characteristics of the interface, thereby providing important theoretical basis and technical support for the design, optimization and operation and maintenance of the cable joint.

[0091] Further, the roughness is adjusted by replacing the replaceable cable sample 202 with different roughness. In the application, the surface of the replaceable cable sample 202 is roughened to simulate the roughness between the 360° circumferential contact interface between the actual cable insulation and the additional rubber insulation. For example, the surface roughness of the replaceable cable sample 202 can be treated by mechanical processing, such as sandpaper polishing, sandblasting, etc. The roughness range is 0.1-2 μm.

[0092] It should be noted that in this document, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusions, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the application is not limited to the order of performing the functions as shown or discussed, but can also include performing the functions in a substantially simultaneous manner or in reverse order, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0093] The above only describes the preferred embodiments of the application and is not intended to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the 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).

2. The test device of claim 1, wherein, 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).

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

4. The test device of claim 2, 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).

5. The test device of claim 4, 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).

6. The test device of claim 4, 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).

7. 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).

8. 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).

9. A method of testing the electrical properties of a cable accessory composite interface using a device as claimed in any one of claims 1 to 8, 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.

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

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