Cable insulation layer short circuit performance detection device and detection method thereof

Abstract

The invention discloses a cable insulation layer short circuit performance detection device and a detection method thereof, and belongs to the field of insulation material short circuit performance detection. The cable insulation layer short circuit performance detection method comprises the following steps: step S100, preparing a heating unit, and preparing a sample unit; s200, the heating unit is powered on, and the temperature of the heating unit rises to the set temperature T; the sample unit is placed on the heating unit, after the placement duration of the sample unit reaches a preset time t, the heating unit is powered off, and the heating unit is naturally cooled to the room temperature; and S300, extracting the sampling layer of the sample unit, and detecting the short-circuit performance of the cable insulation layer. According to the invention, the sample preparation cost and the detection workload in cable insulation layer short circuit performance detection can be reduced, and the anti-short circuit capability of cable insulation layers with different voltage grades and different thicknesses can be detected.

Description

Technical Field

[0001] The present invention application relates to the field of detecting the short - circuit performance of insulating materials, and particularly relates to a device and a detection method for detecting the short - circuit performance of a cable insulating layer. Background Art

[0002] As an infrastructure in modern industries, transportation, communication and other fields, the performance of a cable is directly related to the stability and safety of power and information transmission. The insulating layer of a cable is a key part to ensure the safety of power equipment and personnel. Especially under working conditions such as high voltage, high temperature and complex environments, the insulating performance of the cable is particularly important. With the continuous development of technology, especially the increasing requirements for power transmission efficiency and equipment volume, the cable insulation technology is constantly developing towards higher requirements, and the cable insulation thinning technology has become an important research direction.

[0003] Traditional cable insulating layers are usually composed of multiple layers of materials to ensure safety and stability during power transmission. However, with the growth of power transmission requirements, especially for high - voltage and high - power transmission, the volume and weight of the cable gradually increase, bringing great challenges to transportation, installation and maintenance. Therefore, thinning the cable insulating layer not only helps to reduce the volume and weight of the cable, but also improves the flexibility and adaptability of the cable. The reduction of the cable insulating layer thickness usually affects key performance indicators such as the electric shock resistance and short - circuit resistance of the cable. Especially when a short - circuit occurs, if the insulating layer of the cable does not have sufficient short - circuit resistance, the current flow rate is extremely fast, and the generated heat will rapidly accumulate, which may cause insulation damage, overheating or even fire, thus triggering serious cable safety accidents. Therefore, the research on cable insulation thinning technology not only needs to focus on the thinning of the insulating layer thickness, but also must ensure that the short - circuit performance of the cable after thinning is effectively guaranteed.

[0004] At present, in the existing cable insulation layer short-circuit performance detection technology, in order to detect the influence of different voltage levels and different thicknesses of cable insulation layers under short-term local high temperature conditions during short circuits, the existing cable insulation layer short-circuit performance detection methods include: First, multiple cable specimens with different voltage levels and different thicknesses are usually prepared; then, short-circuit tests are carried out on multiple cable specimens with different voltage levels and different thicknesses one by one; finally, samples of the insulation at different positions of multiple cable specimens with different voltage levels and different thicknesses after short circuits are taken one by one, and the microscopic characterization and electrical test methods are used to analyze and evaluate the short-circuit resistance of cables with different insulation thicknesses. However, when facing the short-circuit performance detection of all cables with different insulation thicknesses and all models, using the existing cable insulation layer short-circuit performance detection method, first, all cable specimens with different insulation thicknesses and all models are prepared separately one by one, which will not only increase the detection cost of the cable insulation layer short-circuit performance detection method, but also make the detection test process of the cable insulation layer short-circuit performance more complicated, directly increasing the workload of the cable insulation layer short-circuit performance detection; in addition, all cable specimens with different insulation thicknesses and all models are tested separately one by one. During the short-circuit test of each cable specimen, due to the large short-term impact current applied, there may also be differences in test conditions, which may lead to large test errors in different groups of tests, resulting in large errors in the detection results of the cable insulation layer short-circuit performance. Therefore, how to improve or optimize the existing cable insulation layer short-circuit performance detection method has become an urgent problem to be solved in the cable insulation layer short-circuit performance detection technology. Summary of the Invention

[0005] The purpose of this application is to provide a cable insulation layer short-circuit performance detection device and its detection method to partially or fully solve the problems existing in the above-mentioned prior art. To achieve the above purpose, the technical solution adopted in this application is as follows:

[0006] In a first aspect, a device for detecting the short-circuit performance of a cable insulating layer is characterized by comprising: a heating unit and a specimen unit. The specimen unit includes a first specimen unit, a second specimen unit, ..., an i-th specimen unit, ..., an n-th specimen unit. Along a first direction, the first specimen unit includes a first insulating layer and a first sampling layer. The first insulating layer is stacked above the heating unit, and the first sampling layer is stacked above the first insulating layer. The second specimen unit includes the first specimen unit, a second insulating layer, and a second sampling layer. The second insulating layer is stacked above the first specimen unit, and the second sampling layer is stacked above the second insulating layer, ..., the i-th specimen unit includes the (i - 1)-th specimen unit, an i-th insulating layer, and an i-th sampling layer. The i-th insulating layer is stacked above the (i - 1)-th specimen unit, and the i-th sampling layer is stacked above the i-th insulating layer, ..., the n-th specimen unit includes the (n - 1)-th specimen unit, an n-th insulating layer, and an n-th sampling layer. The n-th insulating layer is stacked above the (n - 1)-th specimen unit, and the n-th sampling layer is stacked above the n-th insulating layer. The first direction is the thickness direction of the device for detecting the short-circuit performance of the cable insulating layer, i = 2, 3, ..., n, and n is an integer greater than or equal to 2.

[0007] Optionally, along the first direction, the thickness of the first specimen unit is H1, the thickness of the first insulating layer is P1, the thickness of the first sampling layer is S1, the thickness of the second specimen unit is H2, the thickness of the second insulating layer is P2, the thickness of the second sampling layer is S2, ..., the thickness of the i-th specimen unit is Hi, the thickness of the i-th insulating layer is Pi, the thickness of the i-th sampling layer is Si, ..., the thickness of the n-th specimen unit is Hn, the thickness of the n-th insulating layer is Pn, and the thickness of the n-th sampling layer is Sn, satisfying: H1 = P1 + S1, Hi = Di - 1 + Pi + Si.

[0008] Optionally, the thicknesses S1 of the first sampling layer, S2 of the second sampling layer, ..., Si of the i-th sampling layer, ..., Sn of the n-th sampling layer are all equal; along the first direction, the first insulating layer includes M1 stacked unit layers, the second insulating layer includes M2 stacked unit layers, ..., the i-th insulating layer includes Mi stacked unit layers, ..., the n-th insulating layer includes Mn stacked unit layers, and the thickness of the unit layer is SU, satisfying: SU = S1 = Si.

[0009] Optionally, the materials of the first sampling layer, the second sampling layer, ..., the i-th sampling layer, ..., the n-th sampling layer, the first insulating layer, the second insulating layer, ..., the i-th insulating layer, ..., the n-th insulating layer are all the same.

[0010] Optionally, along the first direction, a first anti-sticking layer is disposed between the top surface of the first sampling layer and the bottom surface of the second insulating layer, a second anti-sticking layer is disposed between the top surface of the second sampling layer and the bottom surface of the third insulating layer, ..., an i-th anti-sticking layer is disposed between the top surface of the i-th sampling layer and the bottom surface of the i + 1 insulating layer, ..., an n-th anti-sticking layer is disposed on the top surface of the n-th sampling layer.

[0011] In a second aspect, a method for detecting the short-circuit performance of a cable insulating layer uses any one of the cable insulating layer short-circuit performance detection devices described in the first aspect above and includes:

[0012] Step S100: Prepare a heating unit and a specimen preparation unit;

[0013] Step S200: Connect the heating unit to the power supply, and raise the temperature of the heating unit to the set temperature T; place the specimen unit on the heating unit. After the placement time of the specimen unit reaches the preset time t, disconnect the power supply of the heating unit, and let the heating unit cool naturally to room temperature;

[0014] Step S300: Extract the sampling layer of the specimen unit and detect the short-circuit performance of the cable insulating layer.

[0015] Optionally, step S100 includes:

[0016] Step S101: Prepare a heating unit;

[0017] Step S102: Prepare a specimen unit;

[0018] Step S102 includes:

[0019] Step S1021: Along the first direction, the first specimen unit includes a first insulating layer and a first sampling layer. The first insulating layer is stacked above the electrothermal unit, and the first sampling layer is stacked above the first insulating layer. The first direction is the thickness direction of the cable insulating layer short-circuit performance detection device.

[0020] Step S1022: Along the first direction, the second specimen unit includes the first specimen unit, a second insulating layer, and a second sampling layer. The second insulating layer is stacked above the first specimen unit, and the second sampling layer is stacked above the second insulating layer;..., along the first direction, the i-th specimen unit includes the i - 1 specimen unit, an i-th insulating layer, and an i-th sampling layer. The i-th insulating layer is stacked above the i - 1 test unit, and the i-th sampling layer is stacked above the i-th insulating layer;..., along the first direction, the n-th specimen unit includes the n - 1 specimen unit, an n-th insulating layer, and an n-th sampling layer. The n-th insulating layer is stacked above the n - 1 specimen unit, and the n-th sampling layer is stacked above the n-th insulating layer, where i = 2, 3,..., n, and n is an integer greater than or equal to 2.

[0021] Optionally, step S300 includes:

[0022] Step S301: Extract the sampling layer of the sample unit;

[0023] Step S302: Detect the short - circuit performance of the cable insulation layer;

[0024] Step S301 includes: Extract at least one of the first sampling layer of the first sample unit, the second sampling layer of the second sample unit,..., the i - th sampling layer of the i - th sample unit,..., the n - th sampling layer of the n - th sample unit, and correspondingly extract at least one of the first sample of the first sampling layer, the second sample of the second sampling layer,..., the i - th sample of the i - th sampling layer,..., the n - th sample of the n - th sampling layer.

[0025] Optionally, step S302 includes:

[0026] Step S3021: According to extracting at least one of the first sample of the first sampling layer, the second sample of the second sampling layer,..., the i - th sample of the i - th sampling layer,..., the n - th sample of the n - th sampling layer, correspondingly detect the surface topography of at least one of the first sample, the second sample,..., the i - th sample,..., the n - th sample, and compare and analyze the surface topography of at least one of the first sample, the second sample,..., the i - th sample,..., the n - th sample with the original surface topography of at least one of the corresponding first sample, the second sample,..., the i - th sample,..., the n - th sample to evaluate the short - circuit resistance ability of the cable insulation layer.

[0027] Optionally, step S302 further includes:

[0028] Step S3022: According to extracting at least one of the first sample of the first sampling layer, the second sample of the second sampling layer,..., the i - th sample of the i - th sampling layer,..., the n - th sample of the n - th sampling layer, correspondingly conduct power - frequency breakdown tests on at least one of the first sample, the second sample,..., the i - th sample,..., the n - th sample.

[0029] The beneficial effects brought by the technical solution provided by this application at least include:

[0030] (1) In the application of the present invention, the cable insulation layer short-circuit performance detection device includes a first specimen unit, a second specimen unit,..., an i-th specimen unit,..., an n-th specimen unit. The second specimen unit includes the first specimen unit, the i-th specimen unit includes the (i - 1)-th specimen unit,..., and the n-th specimen unit includes the (n - 1)-th specimen unit. This not only optimizes the structural design of the cable insulation layer specimens, reduces the time cost and material cost in the preparation process of the cable insulation layer specimens, and reduces the redundancy of the number of specimens in the cable insulation layer short-circuit performance detection test, thus significantly reducing the specimen preparation cost and detection workload in the cable insulation layer short-circuit performance detection;

[0031] (2) In the application of the present invention, a short-time high-temperature resistance test can be carried out on insulation specimens with different voltage levels and different thicknesses through a single test. It can not only detect the short-time high-temperature resistance of specimens with different thicknesses, but also simulate and detect the differences and variation laws of the short-circuit resistance capabilities of cable insulation layers with different voltage levels and different thicknesses under short-circuit conditions, providing an important reference basis for exploring the short-circuit resistance capabilities before and after the cable insulation is thinned. At the same time, it also helps researchers comprehensively evaluate the short-circuit performance of the insulation layers of cables with different thicknesses and different models in the test environment, providing technical support for the improvement and optimization of subsequent cable insulation materials. Description of the Drawings

[0032] The drawings are used to provide a further understanding of the present application and constitute a part of the specification. They are used together with the embodiments of the present application to explain the present application and do not constitute a limitation to the present application. In the drawings:

[0033] Figure 1 is a structural schematic diagram of a cable insulation layer short-circuit performance detection device of the present invention application Figure 1 ;

[0034] Figure 2 is a structural schematic diagram of a cable insulation layer short-circuit performance detection device of the present invention application Figure 2 ;

[0035] Figure 3 is a flowchart of a cable insulation layer short-circuit performance detection method of the present invention application;

[0036] Figure 4 is a structural schematic diagram of a specimen unit including a first specimen unit A, a second specimen unit B, and a third specimen unit C of the present invention application;

[0037] Figure 5 is an enlarged structural schematic diagram at position o of the present invention application;

[0038] Figure 6Schematic diagram for comparison of the surface morphologies of the first specimen, the second specimen, the third specimen, and the original specimen D under scanning electron microscope observation in the present invention application ( Figure 6 In (a), it is a schematic diagram of the surface morphology of the first specimen under scanning electron microscope observation, Figure 6 in (b), it is a schematic diagram of the surface morphology of the second specimen under scanning electron microscope observation, Figure 6 in (c), it is a schematic diagram of the surface morphology of the third specimen under scanning electron microscope observation, Figure 6 and in (d), it is a schematic diagram of the surface morphology of the original specimen D under scanning electron microscope observation);

[0039] Figure 7 Schematic diagram for comparison of the power frequency breakdown test results of the first specimen unit A, the second specimen unit B, the third specimen unit C, and the original specimen D in the present invention application; Detailed implementation manners

[0040] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention application. However, it is obvious to those skilled in the art that the present invention application can be implemented without one or more of these details. In other examples, some well-known technical features in the art are not described to avoid confusion with the present invention application.

[0041] Cable Insulation Layer Short-Circuit Performance Detection Device

[0042] In a first aspect, a device for detecting the short-circuit performance of a cable insulation layer includes: a heating unit and a specimen unit. The specimen unit includes a first specimen unit 100, a second specimen unit 200,..., an i-th specimen unit 300,..., an n-th specimen unit 400. Along a first direction, the first specimen unit includes a first insulation layer 101 and a first sampling layer 102. The first insulation layer is stacked above the heating unit, and the first sampling layer is stacked above the first insulation layer. The second specimen unit includes the first specimen unit, a second insulation layer 201, and a second sampling layer 202. The second insulation layer is stacked above the first specimen unit, and the second sampling layer is stacked above the second insulation layer,..., the i-th specimen unit 300 includes the (i - 1)-th specimen unit, an i-th insulation layer 301, and an i-th sampling layer 302. The i-th insulation layer 301 is stacked above the (i - 1)-th test unit, and the i-th sampling layer 302 is stacked above the i-th insulation layer 301,..., the n-th specimen unit 400 includes the (n - 1)-th specimen unit, an n-th insulation layer 401, and an n-th sampling layer 402. The n-th insulation layer 401 is stacked above the (n - 1)-th specimen unit, and the n-th sampling layer 402 is stacked above the n-th insulation layer 401. The first direction is the thickness direction of the device for detecting the short-circuit performance of the cable insulation layer. i = 2, 3,..., n, and n is an integer greater than or equal to 2.

[0043] In some embodiments, the heating unit may include a cast aluminum constant temperature electric heating plate, which is analogous to the semiconductor shielding layer of a cable and provides a stable heat source to simulate the working environment of the cable at high temperatures. The semi-heating unit includes a matrix material containing propylene group and conductive carbon black filler. The matrix material containing propylene group and the conductive carbon black filler achieve a semi-conductive effect through a blending method. According to the regulations on the nominal thickness of the conductor shielding for rated voltage U0 / U in GB / T12706.2 - 2020 (Extruded Insulated Power Cables and Accessories with Rated Voltages from 1 kV to 35 kV) m The following conductor shielding nominal thickness regulations: In 6 - 35 kV medium voltage cables, the nominal thickness of the conductor shielding of the medium voltage cable is 0.8 mm. Thus, when the heating unit serves as the semiconductor shielding layer of the cable, the thickness of the heating unit can be 0.8 mm to correspondingly simulate the nominal thickness of the conductor shielding of the above medium voltage cable and ensure the accuracy of the detection result of the short-circuit performance of the cable insulation layer. Of course, those skilled in the art can also adjust the heating unit material and thickness according to the actual situation to meet the requirements of different cable types and working conditions. This invention application does not make special restrictions on this.

[0044] In some embodiments, the material of the specimen unit can be polypropylene. As an excellent insulating material, polypropylene has good heat resistance and anti-electric shock performance and is suitable for use as a cable insulation layer, providing a good insulation basis for detecting the short-circuit performance of the cable insulation layer.

[0045] Thus, in the cable insulation layer short-circuit performance detection device of the present invention application, first of all, the cable insulation layer short-circuit performance detection device includes a first sample unit, a second sample unit,..., an i-th sample unit,..., an n-th sample unit. The second sample unit includes the first sample unit, the (i + 1)-th sample unit includes the i-th sample unit,..., and the n-th sample unit includes the (n - 1)-th sample unit. This not only optimizes the structural design of the cable insulation layer sample, reduces the time cost and material cost in the preparation process of the cable insulation layer sample, and reduces the redundancy of the number of samples in the cable insulation layer short-circuit performance detection test, thereby greatly reducing the sample preparation cost and detection workload in the cable insulation layer short-circuit performance detection; in addition, short-time temperature resistance tests can be carried out on insulation samples with different voltage levels and different thicknesses through one test. It can not only detect the short-time high-temperature resistance of samples with different thicknesses, but also simulate the differences and variation laws of the short-circuit resistance capabilities of cable insulation layers with different voltage levels and different thicknesses under short-circuit conditions, providing an important reference basis for exploring the short-circuit resistance capabilities before and after the cable insulation is thinned. At the same time, it also helps researchers comprehensively evaluate the short-circuit performance of the insulation layers of cables with different thicknesses and different models in the test environment, providing technical support for the improvement and optimization of subsequent cable insulation materials.

[0046] Optionally, along the first direction, the thickness of the first sample unit is H1, the thickness of the first insulation layer is P1, the thickness of the first sampling layer is S1, the thickness of the second sample unit is H2, the thickness of the second insulation layer is P2, the thickness of the second sampling layer is S2,..., the thickness of the i-th sample unit is Hi, the thickness of the i-th insulation layer is Pi, the thickness of the i-th sampling layer is Si,..., the thickness of the n-th sample unit is Hn, the thickness of the n-th insulation layer is Pn, and the thickness of the n-th sampling layer is Sn, satisfying: H1 = P1 + S1, Hi = Hi-1 + Pi + Si.

[0047] In some embodiments, along the first direction, the thickness H1 of the first sample unit is the distance from the top surface of the first sampling layer to the top surface of the electrothermal unit, the thickness H2 of the second sample unit is the distance from the top surface of the second sampling layer to the top surface of the electrothermal unit,..., the thickness Hi of the i-th sample unit is the distance from the top surface of the i-th sampling layer to the top surface of the electrothermal unit,..., and the thickness Hn of the n-th sample unit is the distance from the top surface of the n-th sampling layer to the top surface of the electrothermal unit.

[0048] In some embodiments, along the first direction, the thickness P1 of the first insulating layer is the distance from the top surface of the first insulating layer to the top surface of the electrothermal unit, and the thickness S2 of the first sampling layer is the distance from the top surface of the first sampling layer to the top surface of the first insulating layer. Since the top surface of the electrothermal unit and the bottom surface of the first insulating layer can be considered to coincide basically, and the top surface of the first insulating layer and the bottom surface of the first sampling layer can be considered to coincide basically, the thickness H1 of the first sample unit and the thickness Hi of the i-th sample unit satisfy: H1 = P1 + S1, Di = Hi-1 + Pi + Si.

[0049] In some embodiments, along the first direction, the insulation thickness D1 of the first sample unit is the distance from the middle position of the first sampling layer to the top surface of the electrothermal unit, the insulation thickness D2 of the second sample unit is the distance from the middle position of the second sampling layer to the top surface of the electrothermal unit,..., the insulation thickness Di of the i-th sample unit is the distance from the middle position of the i-th sampling layer to the top surface of the electrothermal unit,..., and the insulation thickness Dn of the n-th sample unit is the distance from the middle position of the n-th sampling layer to the top surface of the electrothermal unit. Since the top surface of the electrothermal unit and the bottom surface of the first insulating layer can be considered to coincide basically, and the top surface of the first insulating layer and the bottom surface of the first sampling layer can be considered to coincide basically, and taking the middle position of the first sampling layer as a reference, correspondingly, the distance from the middle position of the first sampling layer to the top surface of the electrothermal unit is the sum of the thickness of the first insulating layer and half of the thickness of the first sampling layer, that is, the insulation thickness D1 of the first sample unit satisfies:

[0050] D1 = P1 + S1 / 2; the distance from the middle position of the i-th sampling layer to the top surface of the electrothermal unit is the sum of the insulation thickness Di-1 of the i-1-th sample unit, half of the thickness Si-1 / 2 of the i-1-th sampling layer, the thickness Pi of the i-th insulating layer, and half of the thickness Si / 2 of the i-th sampling layer, that is, the insulation thickness Di of the i-th sample unit satisfies: Di = Di-1 + Pi + (Si-1 + Si) / 2.

[0051] In the application of the present invention, first, a multi-layer stacked sample unit design is adopted. In each test, it is not necessary to separately prepare multiple groups of samples with different thicknesses. Instead, multiple sample units can be prepared by means of hierarchical stacking, reducing the cost and workload of sample unit preparation. In addition, clear mathematical relationships are set for the thickness of each sample unit and the thicknesses of each layer of materials. The mathematical relationships among the thickness of each sample unit, the thickness of each insulating layer, and the thickness of each sampling layer are as follows: H1 = P1 + S1, Hi = Hi-1 + Pi + Si. This can accurately simulate the actual situation of different cable insulating layers in the short-term high-temperature test of the cable insulating layer, detect the differences and variation laws of the short-circuit resistance capabilities of cable insulating layers with different voltage levels and different thicknesses in the short-term high-temperature test environment, providing more accurate data for the detection of the short-circuit resistance performance of the cable insulating layer. In addition, through one test, the short-circuit performance detection data of cable insulating layers with different voltage levels and different thicknesses can be obtained simultaneously. Furthermore, the short-circuit resistance performance after the cable insulating layer is thinned can be effectively and comprehensively evaluated, avoiding the cumbersome process of multiple tests, improving the detection efficiency of the short-circuit resistance performance of the cable insulating layer, and shortening the detection cycle of the short-circuit resistance performance of the cable insulating layer.

[0052] Optionally, the thicknesses S1 of the first sampling layer, S2 of the second sampling layer,..., Si of the i-th sampling layer,..., Sn of the n-th sampling layer are all equal; along the first direction, the first insulating layer includes M1 stacked unit layers, the second insulating layer includes M2 stacked unit layers,..., the i-th insulating layer includes Mi stacked unit layers,..., the n-th insulating layer includes Mn stacked unit layers, and the thickness of the unit layer is SU, satisfying: SU = S1 = Si.

[0053] In some embodiments, the thicknesses S1 of the first sampling layer, S2 of the second sampling layer,..., Si of the i-th sampling layer,..., Sn of the n-th sampling layer are all set to be equal, which means that the sampling materials of each sampling layer have a consistent thickness, ensuring the consistency of the sampling layer and avoiding the inconsistency caused by the thickness difference of the sampling layer. Thus, it is ensured that the physical properties and structures of each sampling layer are the same in the short-term high-temperature test environment of the cable insulating layer, providing a good sampling basis for the comparability of the short-circuit performance detection data of cable insulating layers with different voltage levels and different thicknesses.

[0054] In some embodiments, the first sampling layer, the second sampling layer,..., the i-th sampling layer,..., the n-th sampling layer all include multiple sub-sampling layers. The number of sub-sampling layers of each sampling layer can be set according to the specific requirements and test standards of the short-term high-temperature test of the cable insulating layer. The stacking method of the multiple sub-sampling layers ensures that the electrical performance and heat conduction characteristics of each sampling layer are consistent in the short-term high-temperature test of the cable insulating layer.

[0055] In some embodiments, along the first direction, the first insulating layer includes M1 stacked unit layers, the second insulating layer includes M2 stacked unit layers, ..., the ith insulating layer includes Mi stacked unit layers, ..., and the nth insulating layer includes Mn stacked unit layers. The number of unit layers of each insulating layer can be set according to the specific requirements and test standards of the short-time high-temperature resistance test of the cable insulating layer. The stacking method of multiple unit layers ensures that the electrical performance and heat conduction characteristics of the unit layers of each layer can be accurately reflected in the short-time high-temperature resistance test of the cable insulating layer.

[0056] In some embodiments, the value range of the thickness S1 of the first sampling layer is 50 mm - 1000 mm, and the value range of the thickness Si of the ith sampling layer is 50 mm - 1000 mm. Of course, in this application of the present invention, the thickness S1 of the first sampling layer and the thickness Si of the ith sampling layer can also be set to other values or other value ranges, and this application of the present invention does not make special restrictions on this.

[0057] In this application of the present invention, the thickness SU of each unit layer is equal to the thickness S1 of the first sampling layer and the thickness Si of the ith sampling layer, that is, SU = S1 = Si. The design of the thickness relationship between the unit layer and the sampling layer ensures the consistency of the thickness between the sampling layer and the unit layer, making the thickness of each layer of the specimen unit exactly the same, improving the standardization degree of the specimen unit, simplifying the preparation process of the specimen unit, and also facilitating the rapid measurement of the thicknesses of the first specimen unit, the second specimen unit, ..., the ith specimen unit, ..., the nth specimen unit. Moreover, the heat conduction, insulation performance, etc. between adjacent layers can also be compared and detected under the same conditions, reducing the detection complexity caused by the layer differences of the specimen unit.

[0058] Optionally, the materials of the first sampling layer, the second sampling layer, ..., the ith sampling layer, ..., the nth sampling layer, the first insulating layer, the second insulating layer, ..., the ith insulating layer, ..., the nth insulating layer are all the same.

[0059] In this application of the present invention, the material consistency of all sampling layers and all insulating layers means that: the physical properties such as thermal conductivity, electrical conductivity, and insulation of each layer of material remain consistent throughout the test process, and the property differences between different layers have been minimized, reducing the inconsistencies in aspects such as the coefficient of thermal expansion and resistivity caused by material mismatch. During the short-time high-temperature resistance test of the cable insulating layer, technicians do not need to consider the errors caused by different material types and can focus on the effects of different voltage levels, different thicknesses, etc. on the insulation performance and short-circuit resistance of the cable, reducing the complexity of the short-time high-temperature resistance test of the cable insulating layer.

[0060] Optionally, along the first direction, a first anti-sticking layer is disposed between the top surface of the first sampling layer and the bottom surface of the second insulating layer, a second anti-sticking layer is disposed between the top surface of the second sampling layer and the bottom surface of the third insulating layer, ..., an i-th anti-sticking layer is disposed between the top surface of the i-th sampling layer and the bottom surface of the (i + 1)-th insulating layer, ..., an n-th anti-sticking layer is disposed on the top surface of the n-th sampling layer.

[0061] In some embodiments, in the short-term high-temperature resistance test of the cable insulating layer, in order to prevent adhesion between adjacent test units, the first anti-sticking layer can prevent adhesion between the first specimen unit and the second specimen unit, the second anti-sticking layer can prevent adhesion between the second specimen unit and the third specimen unit, ..., the i-th anti-sticking layer can effectively prevent adhesion between the i-th specimen unit and the (i + 1)-th specimen unit, ..., the (n - 1)-th anti-sticking layer can effectively prevent adhesion between the (n - 1)-th specimen unit and the n-th specimen unit. The first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer ensure the independence of each specimen unit during the experiment; at the same time, the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer can also ensure that the first sampling layer is flat and does not deform, the second sampling layer is flat and does not deform, ..., the i-th sampling layer is flat and does not deform, ..., the (n - 1)-th sampling layer is flat and does not deform, and the n-th sampling layer is flat and does not deform, improving the operability, stability, and repeatability of the short-term high-temperature resistance test of the cable insulating layer.

[0062] In some embodiments, the materials of the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer are all polyester films, and the thickness of the polyester film is 10 μm - 60 μm. The thickness of the polyester film is selected as thin as possible to minimize the error caused by the thickness of the polyester film in the short-term high-temperature resistance test of the cable insulating layer. Preferably, the thickness of the polyester film is 50 μm, and the length and width of the polyester film match the sizes of the corresponding insulating layer and sampling layer.

[0063] Obviously, after the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer are provided, the calculation formulas for the thickness H1 of the first specimen unit, the thickness H2 of the second specimen unit, ..., the thickness Hi of the i-th specimen unit, ..., and the thickness Hn of the n-th specimen unit will change. The applicant further proposes the following calculation update scheme for the thickness H1 of the first specimen unit, the thickness H2 of the second specimen unit, ..., the thickness Hi of the i-th specimen unit, ..., and the thickness Hn of the n-th specimen unit.

[0064] In some embodiments, since the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer are very thin, without considering their influence on the calculation of the thickness H1 of the first sample unit, the thickness H2 of the second sample unit, ..., the thickness Hi of the i-th sample unit, ..., the thickness Hn of the n-th sample unit, the formulas: H1 = P1 + S1, Hi = H i-1 + Pi + Si are still used for calculation and are taken as the thickness H1 of the first sample unit, the thickness H2 of the second sample unit, ..., the thickness Hi of the i-th sample unit, ..., the thickness Hn of the n-th sample unit.

[0065] In some embodiments, considering the influence of the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer, the thicknesses of the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer are all H. Correspondingly, the thicknesses HH1 of the first sample unit, HH2 of the second sample unit, ..., HHi of the i-th sample unit, ..., HHn of the n-th sample unit are respectively:

[0066] HH1 = P1 + S1;

[0067] HH2 = H + D1 + P2 + S2;

[0068] HHi = H + Di-1 + Pi + Si;

[0069] HHn = H + Dn-1 + Pn + Sn.

[0070] In some embodiments, considering the influence of the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer, the thicknesses of the first anti-sticking layer, the second anti-sticking layer, ..., the i-th anti-sticking layer, ..., the (n - 1)-th anti-sticking layer, and the n-th anti-sticking layer are all H. Correspondingly, the insulation thicknesses DH1 of the first sample unit, DH2 of the second sample unit, ..., DHi of the i-th sample unit, ..., DHn of the n-th sample unit are respectively:

[0071] DH1 = P1 + S1 / 2;

[0072] DH2 = H + D1 + P2 + (S1 + S2) / 2;

[0073] DHi = H + Di-1 + Pi + (Si-1 + Si) / 2;

[0074] DHn = H + Dn-1 + Pn + (Sn-1 + Sn) / 2.

[0075] It should be understood that in the present invention application, with the introduction of the i-th anti-sticking layer, those skilled in the art can either consider its impact on the thickness of the specimen unit or approximately ignore or completely disregard its impact on the thickness of the specimen unit. Those skilled in the art can make reasonable settings according to the actual situation, and the present invention application does not make special restrictions on this.

[0076] In some embodiments, when considering the impact of the i-th anti-sticking layer on the thickness of the specimen unit, first of all, by updating the calculation formula, the true thickness of each specimen unit can be calculated more accurately, improving the operation efficiency during the test, enabling the true thickness of the specimen unit to be obtained more quickly, reducing the time waste caused by inaccurate calculation during the experiment, enabling the experimenter to prepare and test the specimen more efficiently, and enhancing the convenience of the overall specimen unit preparation process; in addition, considering the impact of the i-th anti-sticking layer can ensure that the physical size of the specimen unit in the test is more in line with the actual situation, avoiding experimental deviations caused by inconsistent interlayer thicknesses, and thus can more truly simulate the performance of the cable insulation layer under different conditions; furthermore, whether it is a specimen unit with a relatively thin thickness or a relatively thick one, it can adapt to the design and operating conditions of the anti-sticking layer, thereby improving the compatibility and flexibility of the short-time high-temperature test of the entire cable insulation layer, and can be applicable to different test requirements and more test scenarios and test conditions.

[0077] Cable Insulation Layer Short-Circuit Performance Detection Method

[0078] In a second aspect, the present invention application provides a cable insulation layer short-circuit performance detection method, which adopts or does not adopt any of the cable insulation layer short-circuit performance detection devices described in the first aspect above, and includes:

[0079] Step S100: Prepare a heating unit and prepare a specimen unit;

[0080] Step S200: Connect the heating unit to the power supply, and raise the temperature of the heating unit to the set temperature T; place the specimen unit on the heating unit, and after the placement duration of the specimen unit reaches the preset time t, disconnect the power supply of the heating unit, and let the heating unit cool naturally to room temperature;

[0081] Step S300: Extract the sampling layer of the specimen unit and detect the short-circuit performance of the cable insulation layer.

[0082] In some embodiments, in step S100, step S100 includes:

[0083] Step S101: Prepare the heating unit. Exemplarily, the heating unit can be a heating plate, which can provide a stable heat source through electrical energy or other heating methods. First, check whether the power connection of the heating plate is normal and ensure that the temperature control system is operating stably; then, ensure that the surface of the heating plate is clean, without foreign objects or damage, so as not to affect the heating effect. After completing the above preparatory work, subsequent experimental operations can be carried out.

[0084] Step S102: Prepare the specimen unit.

[0085] In some embodiments, step S102 includes:

[0086] Step S1021: Along the first direction, the first specimen unit includes a first insulating layer and a first sampling layer. The first insulating layer is stacked above the electrothermal unit, and the first sampling layer is stacked above the first insulating layer. The first direction is the thickness direction of the cable insulation layer short-circuit performance detection device;

[0087] Step S1022: Along the first direction, the second specimen unit includes the first specimen unit, a second insulating layer, and a second sampling layer. The second insulating layer is stacked above the first specimen unit, and the second sampling layer is stacked above the second insulating layer;..., along the first direction, the i-th specimen unit includes the (i - 1)-th specimen unit, an i-th insulating layer, and an i-th sampling layer. The i-th insulating layer is stacked above the (i - 1)-th test unit, and the i-th sampling layer is stacked above the i-th insulating layer;..., along the first direction, the n-th specimen unit includes the (n - 1)-th specimen unit, an n-th insulating layer, and an n-th sampling layer. The n-th insulating layer is stacked above the (n - 1)-th specimen unit, and the n-th sampling layer is stacked above the n-th insulating layer, where i = 2, 3,..., n, and n is an integer greater than or equal to 2.

[0088] In some implementations, in step S1021, along the first direction, the first specimen unit is composed of a first insulating layer and a first sampling layer. The first insulating layer is stacked above the electrothermal unit, and the first sampling layer is stacked above the first insulating layer. Here, the first direction refers to the thickness direction of the cable insulation layer short-circuit performance detection device. In step S1021, it is necessary to ensure that the stacking relationship between the first insulating layer and the first sampling layer is correct, and their physical positions meet the design requirements of the specimen unit. The material selection and thickness of the first insulating layer need to meet the predetermined standards of the test to ensure that the working state of the cable insulation layer can be accurately simulated.

[0089] In some embodiments, in step S1022, first, continue to construct the second specimen unit in the first direction. The second specimen unit includes the first specimen unit, the second insulating layer, and the second sampling layer. The second insulating layer needs to be stacked above the first specimen unit, and the second sampling layer is to be stacked above the second insulating layer. To ensure that the materials and dimensions of each layer of the second specimen unit meet the expectations, the thickness and physical properties of each layer must be set so that the stacking of the second specimen unit can also simulate the performance of the cable at different thicknesses. Then, according to the actual needs of the short-time high-temperature test of the cable insulating layer, by analogy, the number of specimen units can be gradually increased and stacked step by step to the i-th specimen unit. The i-th insulating layer will be stacked above the (i - 1)-th specimen unit, and the i-th sampling layer will be stacked above the i-th insulating layer. Continuing this analogy, step S1022 continues and can be further extended to more specimen units until finally the n-th specimen unit is constructed. The n-th specimen unit is composed of the (n - 1)-th specimen unit, the n-th insulating layer, and the n-th sampling layer, and the n-th insulating layer is stacked above the (n - 1)-th specimen unit, and the n-th sampling layer is stacked above the n-th insulating layer. This multi-layer stacking process ensures that between the first specimen unit and the n-th specimen unit, the insulating layers and sampling layers are all stacked, forming a specimen unit with a multi-layer stacking structure as a whole. The specimen unit can have good integrity and diversity, and thus can meet the requirements for detecting the short-circuit performance of cable insulating layers with different voltage levels and different thicknesses.

[0090] In some embodiments, the set temperature T is 250 degrees, and the preset time t is 30 s.

[0091] Optionally, in step S300, step S300 includes:

[0092] Step S301: Extract the sampling layer of the specimen unit;

[0093] Specifically, step S301 includes: extracting at least one of the first sampling layer of the first specimen unit, the second sampling layer of the second specimen unit,..., the i-th sampling layer of the i-th specimen unit,..., the n-th sampling layer of the n-th specimen unit, and correspondingly extracting at least one of the first specimen of the first sampling layer, the second specimen of the second sampling layer,..., the i-th specimen of the i-th sampling layer,..., the n-th specimen of the n-th sampling layer.

[0094] Step S302: Detect the short-circuit performance of the cable insulating layer.

[0095] Specifically, step S302 includes:

[0096] Step S3021: Extract at least one of the first specimen from the first sampling layer, the second specimen from the second sampling layer, ..., the i-th specimen from the i-th sampling layer, ..., the n-th specimen from the n-th sampling layer. Correspondingly, detect the surface topography of at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen. Compare and analyze the surface topography of at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen with the original surface topography of at least one of the corresponding first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen to evaluate the short-circuit resistance of the cable insulation layer;

[0097] In some embodiments, it is possible to extract the first specimen from the first sampling layer, the second specimen from the second sampling layer, ..., the i-th specimen from the i-th sampling layer, ..., the n-th specimen from the n-th sampling layer. It is possible to detect at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen. Correspondingly, detect the surface topography of at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen. Furthermore, it is possible to compare and analyze the surface topography of at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen detected with the original surface topography of at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen, and then evaluate the short-circuit resistance of the cable insulation layer.

[0098] Step S3022: Extract at least one of the first specimen from the first sampling layer, the second specimen from the second sampling layer, ..., the i-th specimen from the i-th sampling layer, ..., the n-th specimen from the n-th sampling layer. Correspondingly, perform a power-frequency breakdown test on at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen.

[0099] In some embodiments, in step S3022, correspondingly, a power-frequency breakdown test can be performed on at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen. The power-frequency breakdown test is used to detect the voltage withstand performance of the cable insulation layer at the conventional voltage frequency. During the power-frequency breakdown test, a power-frequency voltage is applied to gradually increase the voltage to the breakdown point of at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen, thereby recording the breakdown voltage of at least one of the first specimen, the second specimen, ..., the i-th specimen, ..., the n-th specimen, and obtaining data such as the breakdown resistance ability of the cable insulation layer at different thicknesses. This helps to analyze and evaluate the electrical stability and electrical insulation performance of the cable insulation layer in the power transmission environment under different thicknesses of the cable insulation layer, providing valuable data references for optimizing the cable insulation layer design, improving the cable's voltage breakdown resistance ability, and ensuring the safe operation of the cable.

[0100] Cable insulation shorts of the first sample unit A, the second sample unit B, and the third sample unit C Example of Road Performance Detection

[0101] (1) Prepare a heating unit and a sample preparation unit.

[0102] Prepare the heating unit: Prepare a hot plate.

[0103] The sample preparation unit includes:

[0104] Step S11: Along the first direction, the first sample unit A includes a first insulating layer and a first sampling layer. The first insulating layer is stacked above the electric heating unit, and the first sampling layer is stacked above the first insulating layer. The first direction is the thickness direction of the cable insulating layer short-circuit performance detection device.

[0105] Step S12: Along the first direction, the second sample unit B includes the first sample unit, a second insulating layer and a second sampling layer. The second insulating layer is stacked above the first sample unit, and the second sampling layer is stacked above the second insulating layer; along the first direction, the third sample unit C includes the second sample unit, a third insulating layer and a third sampling layer. The third insulating layer is stacked above the second sample unit, and the third sampling layer is stacked above the third insulating layer.

[0106] In the example of this invention application, in the extruded insulation power cables and accessories with rated voltages from 1 kV to 35 kV according to GB / T 12706.2-2020, the rated voltage U0 / U m The specified nominal thickness of the lower insulation: The nominal thickness of the insulation of 3.6 / 6 kV cables is 2.5 mm; the nominal thickness of the insulation of 8.7 / 15 kV cables is 4.5 mm; the nominal thickness of the insulation of 26 / 35 kV cables is 10.5 mm. Thus, the insulation thickness of the first sample unit A is D1 = 2.5 mm, the insulation thickness of the second sample unit B is D2 = 4.5 mm, the insulation thickness of the third sample unit C is D3 = 10.5 mm, the voltage class of the first sample unit A is 6 kV, the voltage class of the second sample unit B is 15 kV, and the voltage class of the third sample unit C is 35 kV.

[0107] In the example of the present invention application, the material of the specimen unit is polypropylene, that is, the materials of the first specimen unit A, the second specimen unit B, and the third specimen unit C are the same, all being polypropylene. Along the first direction, the first insulating layer of the first specimen unit A includes 2 unit layers, the second insulating layer of the second specimen unit B includes 1 unit layer, the third insulating layer of the third specimen unit C includes 5 unit layers, the thickness of each unit layer is 1 mm, the thickness of the first sampling layer is 1 mm, the thickness of the second sampling layer is 1 mm, the thickness of the third sampling layer is 1 mm, the first sampling layer includes 5 sub-sampling layers, the second sampling layer includes 5 sub-sampling layers, the third sampling layer includes 5 sub-sampling layers, the thickness of each sub-sampling layer is 200 um, and the thickness of the unit layer, the first sampling layer, the second sampling layer, and the third sampling layer are all equal.

[0108] (2) Connect the heating plate to the power supply, and raise the temperature of the heating plate to the detection temperature of 250 °C; place the specimen unit on the heating plate. After the placement duration of the specimen unit reaches the preset time of 7 s, disconnect the power supply of the heating plate, and let the heating plate cool naturally to room temperature.

[0109] (3) Extract the sampling layers of the specimen unit to detect the short-circuit performance of the cable insulating layer.

[0110] Step S31: Extracting the sampling layers of the specimen unit includes: extracting the first sampling layer of the first specimen unit A, the second sampling layer of the second specimen unit B, and the third sampling layer of the third specimen unit C, and correspondingly extracting the first specimen of the first sampling layer, the second specimen of the second sampling layer, and the third specimen of the third sampling layer.

[0111] Step S32: Detect the short-circuit performance of the cable insulating layer.

[0112] Specifically, step S32 includes:

[0113] Step S321: According to the extraction of the first specimen of the first sampling layer, the second specimen of the second sampling layer, and the third specimen of the third sampling layer, detect the surface morphologies of the first specimen of the first sampling layer, the second specimen of the second sampling layer, and the third specimen of the third sampling layer, and respectively compare and analyze the surface morphologies of the first specimen, the second specimen, and the third specimen with the original surface morphologies of the first specimen, the second specimen, and the third specimen to evaluate the short-circuit resistance ability of the cable insulating layer.

[0114] In the examples of the present invention application, since the materials of the first specimen unit A, the second specimen unit B, and the third specimen unit C are the same, correspondingly, the original surface morphologies of the first specimen, the second specimen, and the third specimen can be considered the same, and the original surface morphology of the original specimen D can be used as the original surface morphologies of the first specimen, the second specimen, and the third specimen.

[0115] As Figure 6 shown, under the scanning observation of an electron microscope, spherical protrusions and rough surface morphologies with depressions appear on the surface morphologies of the first specimen, the second specimen, and the third specimen. The reason is that polypropylene PP is a copolymer material, and the elastomers present in it are spherically dispersed in the PP matrix. Protrusions will form when approaching the brittle fracture surface, and depressions will form when they fall off during brittle fracture.

[0116] Step S322: According to the first specimen extracted from the first sampling layer, the second specimen extracted from the second sampling layer, and the third specimen extracted from the third sampling layer, correspondingly, perform power frequency breakdown tests on the first specimen extracted from the first sampling layer, the second specimen extracted from the second sampling layer, and the third specimen extracted from the third sampling layer.

[0117] As Figure 7 shown, in order to compare the power frequency breakdown test results, the original specimen D also undergoes a power frequency breakdown test. Under the condition of short-term high temperature resistance of the cable insulation layer, due to the recrystallization effect of polypropylene PP, part of the amorphous region converts to the crystalline region, the crystallinity increases slightly, the crystal structure tends to be perfect, the molecular chains of polypropylene PP are arranged more regularly, and the interface between the crystalline region and the amorphous region decreases. During the AC breakdown process, the higher crystalline region hinders the injection of charges and the transportation of carriers, making it difficult for carriers to accelerate under the action of the electric field to obtain sufficient energy to cause impact ionization. The power frequency breakdown field strength of polypropylene PP slightly increases under the condition of short-term high temperature resistance, playing a positive role.

[0118] Those skilled in the art of the present technology can understand that the various operations, methods, steps, measures, and solutions in the processes discussed in the present invention application can be alternated, changed, combined, or deleted; further, other steps, measures, and solutions in the various operations, methods, and processes discussed in the present invention application can also be alternated, changed, rearranged, decomposed, combined, or deleted; further, those in the prior art having the steps, measures, and solutions in the various operations, methods, and processes disclosed in the present invention application can also be alternated, changed, rearranged, decomposed, combined, or deleted. The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the various technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as the scope described in this specification;

[0119] The embodiments described above only represent several implementation manners of the embodiments of the present disclosure. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the embodiments of the present disclosure. It should be noted that for those of ordinary skill in the art, without departing from the concept of the embodiments of the present disclosure, several modifications and improvements can still be made, and these all belong to the protection scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure shall be subject to the appended claims.

Claims

1. A device for detecting the short - circuit performance of a cable insulation layer, characterized in that, Comprising: An electrothermal unit and a specimen unit. The specimen unit includes a first specimen unit, a second specimen unit,..., an i-th specimen unit,..., an n-th specimen unit. Along the first direction, the first specimen unit includes a first insulating layer and a first sampling layer. The first insulating layer is stacked above the electrothermal unit, and the first sampling layer is stacked above the first insulating layer. The second specimen unit includes the first specimen unit, a second insulating layer, and a second sampling layer. The second insulating layer is stacked above the first specimen unit, and the second sampling layer is stacked above the second insulating layer,... The i-th specimen unit includes the (i - 1)-th specimen unit, an i-th insulating layer, and an i-th sampling layer. The i-th insulating layer is stacked above the (i - 1)-th specimen unit, and the i-th sampling layer is stacked above the i-th insulating layer,... The n-th specimen unit includes the (n - 1)-th specimen unit, an n-th insulating layer, and an n-th sampling layer. The n-th insulating layer is stacked above the (n - 1)-th specimen unit, and the n-th sampling layer is stacked above the n-th insulating layer. The first direction is the thickness direction of the cable insulating layer short-circuit performance detection device. i = 2, 3,..., n, and n is an integer greater than or equal to 2.

2. The cable insulation layer short-circuit performance detection device according to claim 1, wherein, Along the first direction, the thickness of the first specimen unit is H1, the thickness of the first insulating layer is P1, the thickness of the first sampling layer is S1, the thickness of the second specimen unit is H2, the thickness of the second insulating layer is P2, the thickness of the second sampling layer is S2,... The thickness of the i-th specimen unit is Hi, the thickness of the i-th insulating layer is Pi, the thickness of the i-th sampling layer is Si,... The thickness of the n-th specimen unit is Hn, the thickness of the n-th insulating layer is Pn, and the thickness of the n-th sampling layer is Sn, satisfying: H1 = P1 + S1, Hi = Hi - 1 + Pi + Si.

3. The cable insulation layer short-circuit performance detection device according to claim 1, characterized in that, The thicknesses S1 of the first sampling layer, S2 of the second sampling layer,..., Si of the i-th sampling layer,..., Sn of the n-th sampling layer are all equal; along the first direction, the first insulating layer includes M1 stacked unit layers, the second insulating layer includes M2 stacked unit layers,... The i-th insulating layer includes Mi stacked unit layers,... The n-th insulating layer includes Mn stacked unit layers. The thickness of the unit layer is SU, satisfying: SU = S1 = Si.

4. A cable insulation layer short-circuit performance detection device according to claim 1, characterized in that, The materials of the first sampling layer, the second sampling layer,..., the i-th sampling layer,..., the n-th sampling layer, the first insulating layer, the second insulating layer,... The i-th insulating layer,... The n-th insulating layer are all the same.

5. The cable insulation layer short-circuit performance detection device according to claim 1, wherein, Along the first direction, a first anti-sticking layer is provided between the top surface of the first sampling layer and the bottom surface of the second insulating layer, a second anti-sticking layer is provided between the top surface of the second sampling layer and the bottom surface of the third insulating layer,... An i-th anti-sticking layer is provided between the top surface of the i-th sampling layer and the bottom surface of the (i + 1)-th insulating layer,... A n-th anti-sticking layer is provided on the top surface of the n-th sampling layer.

6. A method for detecting the short - circuit performance of a cable insulation layer, using the device for detecting the short - circuit performance of a cable insulation layer according to any one of claims 1 - 5 above, characterized in that, Comprising: Step S100: Prepare a heating unit and fabricate a specimen unit; Step S200: The heating unit is powered on, and the temperature of the heating unit rises to the set temperature T; the specimen unit is placed on the heating unit. After the placement duration of the specimen unit reaches the preset time t, the heating unit is powered off, and the heating unit cools naturally to room temperature; Step S300: Extract the sampling layer of the specimen unit and detect the short - circuit performance of the cable insulation layer.

7. A method for detecting the short - circuit performance of a cable insulation layer according to claim 6, characterized in that, Step S100 includes: Step S101: Prepare the heating unit; Step S102: Prepare the specimen unit; Step S102 includes: Step S1021: Along the first direction, the first specimen unit includes a first insulation layer and a first sampling layer. The first insulation layer is stacked above the electro - thermal unit, and the first sampling layer is stacked above the first insulation layer. The first direction is the thickness direction of the cable insulation layer short - circuit performance detection device. Step S1022: Along the first direction, the second specimen unit includes the first specimen unit, a second insulation layer, and a second sampling layer. The second insulation layer is stacked above the first specimen unit, and the second sampling layer is stacked above the second insulation layer;..., along the first direction, the i - th specimen unit includes the (i - 1) - th specimen unit, an i - th insulation layer, and an i - th sampling layer. The i - th insulation layer is stacked above the (i - 1) - th test unit, and the i - th sampling layer is stacked above the i - th insulation layer;..., along the first direction, the n - th specimen unit includes the (n - 1) - th specimen unit, an n - th insulation layer, and an n - th sampling layer. The n - th insulation layer is stacked above the (n - 1) - th specimen unit, and the n - th sampling layer is stacked above the n - th insulation layer, where i = 2, 3,..., n, and n is an integer greater than or equal to 2.

8. A method for detecting the short-circuit performance of a cable insulation layer according to claim 7, wherein Step S300 includes: Step S301: Extract the sampling layer of the specimen unit; Step S302: Detect the short - circuit performance of the cable insulation layer; Step S301 includes: Extract at least one of the first sampling layer of the first specimen unit, the second sampling layer of the second specimen unit,..., the i - th sampling layer of the i - th specimen unit,..., the n - th sampling layer of the n - th specimen unit, and correspondingly extract at least one of the first specimen of the first sampling layer, the second specimen of the second sampling layer,..., the i - th specimen of the i - th sampling layer,..., the n - th specimen of the n - th sampling layer.

9. A method for detecting the short - circuit performance of a cable insulating layer according to claim 8, characterized in that, Step S302 includes: Step S3021: According to extracting at least one of the first specimen of the first sampling layer, the second specimen of the second sampling layer,..., the i - th specimen of the i - th sampling layer,..., the n - th specimen of the n - th sampling layer, correspondingly detect the surface morphology of at least one of the first specimen, the second specimen,..., the i - th specimen,..., the n - th specimen, and compare and analyze the surface morphology of at least one of the first specimen, the second specimen,..., the i - th specimen,..., the n - th specimen with the original surface morphology of at least one of the corresponding first specimen, the second specimen,..., the i - th specimen,..., the n - th specimen to evaluate the short - circuit resistance ability of the cable insulation layer.

10. A method for detecting the short - circuit performance of a cable insulation layer according to claim 9, characterized in that, Step S302 also includes: Step S3022: At least one of the first sample from the first sampling layer, the second sample from the second sampling layer, ..., the i-th sample from the i-th sampling layer, ..., the n-th sample from the n-th sampling layer is extracted, and correspondingly, at least one of the first sample, the second sample, ..., the i-th sample, ..., the n-th sample is subjected to a power frequency breakdown test.

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