Method and device for checking performance of insulating paperboard

Abstract

The invention provides a method and a device for checking the performance of an insulating paperboard. The method comprises the following steps: determining a test boundary threshold value and an acceptable reject ratio of a to-be-checked insulating paperboard; carrying out an insulating property test on the batch of insulating paperboards to be tested, and fitting test data to obtain a failure probability function; and judging a test result in the insulation performance test on the basis of the threshold value and the acceptable reject ratio of the to-be-detected insulation paperboard. In the test electrode design process, the applicability of batch test, the electric field uniformity of a test device and the equivalence of a test electric field and an actual electric field are considered at the same time, so that the test result is more accurate, and the result deviation caused by local electric field distortion of the test device is avoided; test results are judged by adopting a statistical analysis method, and the method has relatively strong adaptability to the characteristics of high oil paper insulation discharge dispersity and more batch test data; and batch testing can be conveniently carried out, and the testing efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to the field of high voltage and insulation technology, and in particular to a method and device for evaluating the performance of insulating paperboard. Background Art

[0002] Insulation materials are the core components of power transmission and transformation equipment. Taking ultra-high voltage converter transformers as an example, the highest voltage level converter transformer is worth up to 100 million yuan. It is one of the most core equipment in DC transmission and transformation projects. Product failures can cause great losses and are the most critical factor affecting the commissioning of projects.

[0003] In actual projects, with the continuous improvement of design and process levels, material problems have become more and more prominent and are the main factor leading to product defects. Power product defects are largely caused by insulation material problems, and the lack of effective assessment methods is the main reason for this problem.

[0004] The fundamental reason why the problem of insulating materials is not easy to be found is that in the national standards and various testing standards, it is impossible to simulate the operating conditions under laboratory conditions, and it is difficult to assess the true level of insulating materials. For example, the national standard requires that when insulating materials leave the factory, only the breakdown strength of small-sized samples in oil and air is tested. The initial discharge of small-sized models mostly occurs in the local discharge of high electric field strength areas, that is, the contact surface in the extremely non-uniform electric field and the tip of the wedge-shaped oil gap in the slightly non-uniform electric field formed by the column-plate electrode. Therefore, its test results depend more on the electric field strength at the "three-junction point" formed by the electrode, oil and paperboard, and are not strongly related to the physical and chemical and dielectric properties of the oil-immersed paperboard, such as the tightness, polymerization degree, embossing arrangement, moisture content, conductivity, relative dielectric constant, etc., and the surface insulation performance of the oil-immersed paperboard cannot be effectively assessed. In addition, since the creepage distance of the small-sized model is very small and the discharge development speed is very fast, it is difficult to study the large-sized discharge in the transformer using a small-sized model. Summary of the invention

[0005] In view of this, the present invention proposes an insulating paperboard performance assessment method and device, aiming to solve the problem in the prior art that the insulation performance of a large number of insulating material samples sampled for engineering sampling cannot be assessed in batches, resulting in low efficiency.

[0006] In one aspect, the present invention provides a method for evaluating the performance of insulating paperboard, comprising the following steps:

[0007] Determine the test boundary threshold and acceptable defect rate of the insulation paperboard to be tested;

[0008] Conduct insulation performance tests on batches of insulation paperboards to be tested, and fit the test data to obtain a failure probability function;

[0009] The test result in the insulation performance test is judged based on the threshold value and the acceptable defective rate of the insulating paperboard to be tested.

[0010] Furthermore, in the above-mentioned insulation paperboard performance assessment method, the expected defective properties of the insulation paperboard to be tested are

[0011] Rate P a (p) is determined by the following formula:

[0012] Where p is the defective rate of a single sample of the tested batch of insulation paperboard, X is used to represent the number of unqualified samples, P a (p) represents the acceptance probability when the defective rate of the tested batch is p, n is the number of samples, and n is greater than or equal to 1.

[0013] Furthermore, in the above-mentioned insulation paperboard performance assessment method, the fitting of the failure probability function P(E)

[0014] The formula is as follows:

[0015] in,

[0016] P(E) is the failure probability when the measured value is E, E is the surface electric field strength of the insulating paperboard located in the middle part of the insulating paperboard batch to be tested; α is the scale parameter, β is the shape parameter, and E0 is the deviation parameter.

[0017] Furthermore, in the above-mentioned insulation paperboard performance assessment method, the insulation performance assessment device for conducting insulation performance tests on the batch of insulation paperboards to be tested must meet the following conditions when designed:

[0018] U lms / U lmm <1.1, and U mt / U dt <1.2; among which, U lmm is the electric field strength along the surface of the insulating paperboard to be tested in the middle part, U lms is the surface electric field strength of the insulating paperboard to be tested at the two ends; U dt is the average electric field strength in the oil gap at the end of the corresponding test electrode;

[0019] If you cannot satisfy U mt / U dt <1.2, a metal shielding sleeve should be provided at the end of the test electrode, or a metal shielding cover should be provided at the connecting rod of the test electrode.

[0020] Furthermore, in the above-mentioned insulation paperboard performance assessment method, the following formula is used to evaluate the insulation to be tested:

[0021] The batch eligibility of cardboard is determined by:

[0022] E r ≥E n ; E n is the maximum electric field component along the surface of the insulating paperboard, E r is the actual electric field strength of the tested batch of insulating paperboard; P(E)<Pa(p); it means that this batch of products is judged to be qualified.

[0023] In the design process of the test electrode in the present invention, the applicability of batch testing, the electric field uniformity of the test device, and the equivalence of the test electric field and the actual electric field are taken into consideration at the same time, so that the test result is more accurate and the result deviation introduced by the local electric field distortion of the test device is avoided; the test result is determined by a statistical analysis method, which has strong adaptability to the characteristics of large dispersion of oil-paper insulation discharge and a large amount of batch test data; it is easy to carry out batch testing and greatly improve the test efficiency.

[0024] On the other hand, the present invention also proposes an insulating paperboard performance assessment device, comprising: a test box, a first test electrode and a second test electrode; wherein:

[0025] The first test electrode and the second test electrode are arranged opposite to each other inside the test box, and two ends of the first test electrode and the second test electrode are respectively connected to the outside of the test box through lead wires;

[0026] The first test electrode and the second test electrode are provided with a plurality of groups of clamping parts corresponding to each other, and are used to clamp a plurality of insulating paperboards to be tested respectively.

[0027] Furthermore, in the above-mentioned insulating paperboard performance assessment device, the first test electrode and the second test electrode are layered structures, wherein the gaps between the layered structures form the sandwiching portion.

[0028] Furthermore, in the above-mentioned insulating paperboard performance assessment device, the first test electrode and the second test electrode are both wavy electrodes.

[0029] Furthermore, in the above-mentioned insulating paperboard performance assessment device, the ends of the first test electrode and the second test electrode are both provided with shielding sleeves, the shielding sleeves are in an elliptical ring-shaped structure, and the arc radii of the narrow sides of the shielding sleeves are R1 and R3 respectively, and R1=R3>R0+D1, wherein R0 is the single-side radius of the wavy electrode; D1 is the thickness of the shielding sleeve.

[0030] Furthermore, in the above-mentioned insulating paperboard performance assessment device, a shielding cover is provided at the position where the first test electrode and the second test electrode are connected to the lead, and the shielding cover is an annular shell with an opening on one side, R4 is the curvature radius of the shielding cover, R4>4R0, wherein R0 is the single-side radius of the wavy electrode.

[0031] In the insulating paperboard performance assessment device provided by the present invention, by providing a plurality of groups of clamping parts on the first test electrode and the second test electrode in a one-to-one correspondence, batch testing of the insulating paperboards to be tested can be achieved, thereby greatly improving the testing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0033] Figure 1 A flow chart of a method for evaluating the performance of insulating paperboard provided in an embodiment of the present invention;

[0034] Figure 2 A fitting curve diagram of failure probability in the insulation paperboard performance assessment method provided in an embodiment of the present invention;

[0035] Figure 3 A side view of a test electrode in an insulating paperboard performance assessment device provided by an embodiment of the present invention;

[0036] Figure 4 A top view of a test electrode in an insulating paperboard performance assessment device provided by an embodiment of the present invention;

[0037] Figure 5 Another structural schematic diagram of the test electrodes in the insulating paperboard performance assessment device provided by an embodiment of the present invention;

[0038] Figure 6 A cross-sectional view of a shielding sleeve in an insulating paperboard performance assessment device provided by an embodiment of the present invention;

[0039] Figure 7 A cross-sectional view of a shielding cover in an insulating paperboard performance assessment device provided by an embodiment of the present invention;

[0040] Figure 8 This is a diagram of the electric field simulation results of the side-view electrodes in the insulating paperboard performance assessment device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] See also Figure 1 The insulation paperboard performance assessment method of the embodiment of the present invention comprises the following steps:

[0043] Step S1, determining the test boundary threshold and acceptable defect rate of the insulating paperboard to be tested.

[0044] Specifically, the electric field strength under actual operating conditions at the place where the tested batch of insulating paperboard is used is first calculated as the basis for selecting the applied electric field during the assessment, that is, the test boundary threshold.

[0045] In the specific implementation, according to the finite element simulation verification results of the transformer insulation structure electric field, the maximum electric field component value along the surface of the insulation cardboard in the entire transformer main insulation domain is extracted as the test boundary threshold E n This step is usually completed with the assistance of commercial finite element simulation software, such as ANSYS, COMSOL, etc. n It can be 1.3.

[0046] When determining the acceptable defective rate of the insulating paperboard to be tested, the acceptable defective rate of this batch of paperboard during the assessment is determined according to the application product type or voltage level of the batch of insulating paperboard to be tested, which is used as the basis for judging the assessment results. For insulating paperboard used in high-field strength areas of ultra-high voltage transformers, the acceptable defective rate is required to be less than 0.1%, and for conventional power transformers, the acceptable defective rate of insulating paperboard is less than 1.0%, which can be determined according to the requirements of transformer users.

[0047] In specific implementation, n products are randomly selected from the batch of insulation paperboards to be tested for sampling inspection. First, the acceptance judgment number Ac (the maximum number of unqualified products allowed in the sampling inspection) is selected according to the voltage level of the transformer. Generally speaking, the higher the voltage level, the lower the acceptance judgment number. According to the acceptance judgment number Ac, the expected defective rate Pa(p) of the product is calculated. Pa(p) is determined by the following formula:

[0048] Where p is the defective rate of a single sample of this batch of insulation paperboard, and X represents the number of unqualified samples in the sample. This number is a random variable, that is, when "X=1", "X=2", "X=3"... "X=d"... until "X=A c ", in these cases, the batch of products can be considered acceptable. Since these events are independent events, P a (p) represents the acceptance probability of a batch when the defective rate is p, n is the sampling number (n is greater than or equal to 1), and the size of n is determined by the total amount of products in this batch.

[0049] Preferably, the insulating paperboard used in the high field strength area of ​​the UHV transformer is tested, so the acceptance judgment number is Ac=0 and substituted into the above formula, that is, defective products are not accepted. For the insulating paperboard used in the high field strength area of ​​the ultra-ultra-high voltage transformer, the acceptable defect rate is required to be less than 0.1%, and for conventional power transformers, the acceptable defect rate of the insulating paperboard is less than 1.0%, which can be specifically determined according to the requirements of the transformer user.

[0050] Step S2, conducting insulation performance tests on a batch of insulating paperboards to be tested, recording the test data and fitting the test data to obtain a failure probability function P(E).

[0051] In the specific implementation, record the voltage U when the insulating cardboard to be tested breaks down, and substitute it into finite element software such as ANSYS, COMSOL and other software to assist in calculating the surface electric field strength E of the insulating cardboard in the middle part at this time (during the test, when discharge occurs, exclude the insulating cardboards at both ends, and take the test results of the middle n-2 cards as the average). Continue to carry out the test. Since the discharge is dispersed, breakdown may not occur every time at this voltage. The probability of breakdown recorded at this electric field strength is recorded as P(E). Fit the failure probability function P(E) based on the insulation performance test data. The fitting formula of the failure probability function P(E) is as follows:

[0052] in,

[0053] P(E) is the failure probability when the measured value is E, α is the scale parameter, β is the shape parameter, and E0 is the deviation parameter. This part can be fitted by commercial statistical analysis software such as SPSS, Matlab, etc.

[0054] In this embodiment, it is necessary to design corresponding test electrodes to make an assessment device, which includes a box and two test electrodes with a mounting portion. The two test electrodes can be a high-voltage electrode and a low-voltage electrode. The maximum electric field strength U in the oil gap at the end of the high-voltage electrode or the low-voltage electrode is calculated by electric field simulation. mt , test the average electric field strength U in the oil gap at the end of the high-voltage electrode or low-voltage electrode dt, and the electric field strength U along the surface of the insulating paperboard to be tested in the middle part lmm , the electric field strength U along the surface of the insulation paperboard to be tested at the two ends lms , by iteratively adjusting the structure of the high voltage electrode or the low voltage electrode, to ensure that the electric field strength of the high voltage electrode and the low voltage electrode meet the following conditions: U lms / U lmm <1.1, and U mt / U dt <1.2; if U cannot be satisfied mt / U dt <1.2, a metal shielding sleeve should be installed at the end of the corresponding test electrode, or a metal shielding cover should be installed at the electrode connecting rod, and the size of the shielding sleeve should be adjusted until the above requirements are met.

[0055] In this embodiment, the ground electrode and the high voltage electrode are consistent and symmetrically arranged, which makes it convenient to carry and wire them during the test operation.

[0056] Step S3, judging the result of the insulation performance test based on the threshold value and the acceptable defective rate of the insulating paperboard to be tested.

[0057] The batch qualification of the insulating paperboard to be tested is determined by using the following formula. It is necessary to ensure that the surface electric field strength applied to the middle layer of insulating paperboard in the test is equivalent to the actual electric field strength of the insulating paperboard to be tested, and the failure probability is less than the expected defective rate, that is,

[0058] E r ≥E n ; E n is the maximum electric field component along the surface of the insulating paperboard, E r is the actual electric field strength of the tested batch of insulating paperboard; P(E)<Pa(p) indicates that the tested batch of insulating paperboard is qualified.

[0059] See also Figure 2 , is the assessment result of a batch of insulating paperboards. Through the failure probability fitting result, when E0=2.5, E is calculated according to the actual use position of this paperboard in the transformer product. n =1.3, it is judged that the test results of this batch of samples are qualified.

[0060] It can be obviously concluded from the above that the insulation paperboard performance assessment method provided in this embodiment determines the test boundary threshold of the insulation paperboard to be tested and the acceptable defective rate to design the corresponding test electrode, so as to carry out insulation performance tests on batches of insulation paperboards to be tested and make judgment results. It can be applied to batch assessment of random inspections of converter transformer insulation materials for UHV projects, which can greatly improve the test efficiency and solve the problem of disconnection between test assessment and actual project operation.

[0061] See also Figure 3 and Figure 4 The present invention also provides an insulating paperboard performance assessment device, comprising: a test box 1, a first test electrode 2 and a second test electrode 3; wherein the first test electrode 2 and the second test electrode 3 are arranged relatively inside the test box 1, and the two ends of the first test electrode 2 and the second test electrode 3 are respectively connected to the outside of the test box 1 through leads;

[0062] The first test electrode 2 and the second test electrode 3 are provided with a plurality of groups of clamping parts corresponding to each other, for clamping a plurality of insulating paperboards 4 to be tested respectively.

[0063] Specifically, a bracket is provided on the bottom plate inside the test box 1 to fix two test electrodes. Among the first test electrode 2 and the second test electrode 3, the one connected to an external high-voltage power supply is the high-voltage electrode, and the one connected to an external grounding wire is the ground electrode.

[0064] In specific implementation, the first test electrode 2 and the second test electrode 3 may have the same shape and structure. In a specific implementation of this embodiment, the side walls of the test electrodes are provided with a plurality of grooves for placing the insulating paperboard 4 to be tested.

[0065] In another specific implementation of this embodiment, the first test electrode 2 and the second test electrode 3 are layered structures, such as wavy plate-shaped, multi-layer circular ring electrodes, multi-layer disc electrodes, multi-layer mesh structures and other similar layered structures. When a high voltage is applied externally, the local electric field strength in the wedge-shaped oil gap can be reduced, and at the same time, multiple layers of insulating paperboard can be measured under the same conditions. In this embodiment, the test electrode is preferably a wavy plate structure, which has a simple structure, saves materials, and is convenient for batch testing, greatly improving the test efficiency. More specifically, the test electrode is pressed into a wavy shape from a copper plate or an aluminum plate, such as Figure 5 As shown. Each wave is approximately a semicircle, with a single-side radius of R0. Assuming that the thickness of the insulating paperboard 4 to be tested is d, 6d≤R0≤10d is taken to ensure that there are enough oil channels after the insulating paperboard sample is placed at the wave position, and the electric field will not be seriously distorted due to the local wedge-shaped oil gap, thereby interfering with the test results.

[0066] During actual testing, each insulating paperboard 4 to be tested is placed between the clamping portions a formed by two opposite wave crests of the corrugated plate.

[0067] In order to reduce the electric field distortion during testing, preferably, both ends of the first test electrode 2 and the second test electrode 3 are provided with 5 .

[0068] In practice, the shielding sleeve 5 may be an elliptical ring-shaped shell with an opening, and the size of the opening may be sufficient to accommodate the end of the test electrode.

[0069] See also Figure 6 The shielding sleeve at the edge of the test electrode can be integrally pressed from an aluminum plate with chamfered edges. R1 and R3 are the arc radii of the narrow side of the shielding sleeve, and D1 is the thickness of the shielding sleeve. When designed, R1=R3>R0+D1.

[0070] Further preferably, a shielding cover 6 is provided at the portion where the first test electrode 2 and the second test electrode 3 are connected to the lead 7 .

[0071] In practice, the shielding cover 6 may be an annular shell with an opening on one side, and the opening may be arranged toward the side wall of the box.

[0072] In this embodiment, the shielding cover and the shielding sleeve are provided to make the electric field in the oil gap around the electrode uniform.

[0073] like Figure 7 As shown, R4 is the curvature radius of the shielding cover, R4>4R0.

[0074] In this embodiment, a shielding sleeve is provided at the end of the test electrode, and a shielding cover is provided at both ends of the lead wire, which can reduce the electric field distortion at the end of the electrode during the test and make the test result more accurate.

[0075] The installation and testing method of the test device in this embodiment is as follows:

[0076] 1) Fix the corrugated plate on the bracket 8 at the bottom of the test box 1;

[0077] 2) Shielding sleeve for the end of the test electrode

[0078] 3) Fix the leads connecting the two ends of the test electrodes;

[0079] 4) Install the lead shield;

[0080] 5) Insert the insulating cardboard sample to be tested, and record the number of samples as n;

[0081] 6) During the test, when discharge occurs, the cardboards at both ends are excluded and the test results of the middle n-2 cards are taken as the average.

[0082] The electric field strength in the vicinity of the test electrode is calculated, such as Figure 8 The electric field intensity cloud diagram in this example is shown, and the U in this embodiment is calculated. lms / U lmm =1.05, and U mt / U dt =1.18, U lms =1.58kV / mm; U lmm=1.50kV / mm; U mt =6.89kV / mm; U dt =5.84 kV / mm. From the results, it can be seen that the test device of this embodiment meets the design requirements.

[0083] It should be noted that the two electrodes in this embodiment are arranged left and right, and the insulating paperboard 4 to be tested is placed vertically. The same test effect can be achieved by adopting other arrangement directions, such as placing the test electrodes and the insulating paperboard 4 to be tested horizontally.

[0084] The insulating paperboard performance assessment device provided by the present invention reasonably sets the shape and curvature of the test electrode, and uses the clamping portion a of the first test electrode 2 and the second test electrode 3 and the insulating paperboard to divide the insulating oil space into oil gaps to reduce the electric field strength in the insulating oil. The design of a batch assessment device suitable for random inspection of converter transformer insulation materials for ultra-high voltage projects can be carried out, which greatly improves the test efficiency and solves the problem of disconnection between test assessment and actual project operation.

[0085] In summary, the insulation paperboard performance assessment method provided by the present invention has the following beneficial effects:

[0086] A more reasonable acceptable defective rate selection scheme is proposed for large quantities of insulating paperboard; in the process of designing the test electrode, the applicability of batch testing, the electric field uniformity of the test device, and the equivalence of the test electric field and the actual electric field are taken into consideration at the same time, so that the test results are more accurate and the result deviation introduced by the local electric field distortion of the test device is avoided; the test results are determined by statistical analysis methods, which has strong adaptability to the characteristics of large discharge dispersion of oil-paper insulation and large amount of batch test data; it is easy to carry out batch testing and greatly improve the test efficiency.

[0087] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for evaluating the performance of insulating paperboard, characterized in that: The following steps are involved: Determine the test boundary threshold and acceptable defect rate of the insulation paperboard to be tested; Conduct insulation performance tests on batches of insulation paperboards to be tested, and fit the test data to obtain a failure probability function; The test result in the insulation performance test is judged based on the threshold value and the acceptable defective rate of the insulating paperboard to be tested.

2. The insulation paperboard performance assessment method according to claim 1 is characterized in that: The expected defective rate P of the insulating paperboard to be tested a (p) is determined by the following formula: Where p is the defective rate of a single sample of the tested batch of insulation paperboard, X is used to represent the number of unqualified samples, P a (p) represents the acceptance probability when the defective rate of the tested batch is p, n is the number of samples, and n is greater than or equal to 1.

3. The insulation paperboard performance assessment method according to claim 1, characterized in that: The fitting formula of the failure probability function P(E) is as follows: in, P(E) is the failure probability when the measured value is E, E is the surface electric field strength of the insulating paperboard located in the middle part of the insulating paperboard batch to be tested; α is the scale parameter, β is the shape parameter, and E0 is the deviation parameter.

4. The insulation paperboard performance assessment method according to claim 1, characterized in that: The insulation performance assessment device for conducting insulation performance tests on the batch of insulation paperboards to be tested must meet the following conditions when being designed: U lms / U lmm <1.1, and U mt / U dt <1.2; among which, U lmm is the electric field strength along the surface of the insulating paperboard to be tested in the middle part, U lms is the surface electric field strength of the insulating paperboard to be tested at the two ends; U dt is the average electric field strength in the oil gap at the end of the corresponding test electrode; If you cannot satisfy U mt / U dt <1.2, a metal shielding sleeve should be provided at the end of the test electrode, or a metal shielding cover should be provided at the connecting rod of the test electrode.

5. The insulation paperboard performance assessment method according to claim 1, characterized in that: The batch eligibility of the insulating paperboard to be tested is determined by the following formula: E r ≥E n ; E n is the maximum electric field component along the surface of the insulating paperboard, E r is the actual electric field strength of the batch of insulating paperboard to be tested; P(E)<Pa(p); it means that this batch of insulating paperboard is judged to be qualified.

6. An insulating paperboard performance assessment device, characterized in that: include: A test box, a first test electrode and a second test electrode; wherein, The first test electrode and the second test electrode are arranged opposite to each other inside the test box, and two ends of the first test electrode and the second test electrode are respectively connected to the outside of the test box through lead wires; The first test electrode and the second test electrode are provided with a plurality of groups of clamping parts corresponding to each other, and are used to clamp a plurality of insulating paperboards to be tested respectively.

7. The insulating paperboard performance assessment device according to claim 6 is characterized in that: The first test electrode and the second test electrode are layered structures, wherein the gaps between the layered structures form the sandwich portion.

8. The insulating paperboard performance assessment device according to claim 7 is characterized in that: The first test electrode and the second test electrode are both wavy electrodes.

9. The insulating paperboard performance assessment device according to claim 8, characterized in that: The ends of the first test electrode and the second test electrode are both provided with shielding sleeves, and the shielding sleeves are in an elliptical ring-shaped structure. The arc radii of the narrow sides of the shielding sleeves are R1 and R3 respectively, and R1=R3>R0+D1, wherein R0 is the single-side radius of the wavy electrode; and D1 is the thickness of the shielding sleeve.

10. The insulating paperboard performance assessment device according to claim 8, characterized in that: A shielding cover is provided at the position where the first test electrode and the second test electrode are connected to the lead. The shielding cover is an annular shell with an opening on one side. R4 is the curvature radius of the shielding cover, R4>4R0, wherein R0 is the single-side radius of the wavy electrode.

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