A method for evaluating the insulating properties of organic composite solid insulation materials

Abstract

The application provides a method for evaluating the insulation performance of organic composite solid insulation material. The application researches and finds that the porosity and electrical strength of the organic composite solid insulation material satisfy the following relation: Y = - [(M / 100000*2.52) + 0.005]X + (19 + 2); wherein Y is the electrical strength, X is the porosity, and M is the number average molecular weight of the polymer matrix. The evaluation method of the application starts from the organic composite solid insulation material, tests the porosity and electrical performance of the organic composite solid insulation material, and establishes a correlation between the porosity and the insulation performance of the organic composite solid insulation material. Using the evaluation method, on one hand, the insulation performance of the organic composite solid insulation material can be simply and quickly evaluated; on the other hand, the occurrence of unqualified electric appliance products can be reduced from the root, thereby reducing the cost and reducing the personnel casualty.

Description

Technical Field

[0001] This invention relates to the field of electrical technology, and in particular to a method for evaluating the insulation performance of organic composite solid insulating materials. Background Technology

[0002] Organic composite solid insulating materials, with their advantages of good insulation, high electric field strength, and ease of processing, are used for insulation of power equipment and are increasingly widely used in power grids. For example, epoxy resin is a thermosetting resin, and due to its excellent mechanical properties, electrical properties, and low cost, it is widely used in the electrical industry, rail transportation, new energy, and other fields.

[0003] However, during the preparation of organic composite solid insulation materials, different processes can result in pores of varying sizes and numbers within the material, affecting its mechanical and electrical properties during use. Currently, domestically produced composite solid insulation materials are mainly used for low-voltage applications. However, breakdown incidents involving composite solid insulation materials occur frequently. The discharge process is usually characterized by high energy and short duration, leading to instantaneous breakdown, fires, and explosions in electrical equipment. This makes it impossible to analyze the cause of the discharge and can also cause personal injury or death, posing a significant hazard.

[0004] Therefore, it is very important to evaluate the insulation performance of organic composite solid insulating materials. Summary of the Invention

[0005] The purpose of this invention is to provide a simple, rapid, and accurate method for evaluating the insulation performance of organic composite solid insulating materials. This invention establishes a correlation between porosity and the insulation performance (especially electrical strength) of organic composite solid insulating materials by testing their porosity. This allows for a simple and rapid assessment of the insulation performance of organic composite solid insulating materials and their suitability for manufacturing electrical products, thereby reducing the occurrence of breakdown events and minimizing personal injury.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for evaluating the insulation performance of organic composite solid insulating materials, satisfying the following relationship:

[0008] Y=-[(M / 100000×2.52)±0.005]X+(19±2)

[0009] Wherein, Y is the electrical strength of the organic composite solid insulating material, in kV / mm; M is the number-average molecular weight of the polymer matrix in the organic composite solid insulating material, in g / mol; and X is the porosity of the organic composite solid insulating material, in units of %.

[0010] The evaluation method of this invention starts with organic composite solid insulating materials. By testing the porosity and electrical properties of these materials, a correlation is established between porosity and the insulation performance (especially electrical strength) of the organic composite solid insulating materials. Using this evaluation method, on the one hand, the insulation performance of organic composite solid insulating materials can be assessed simply and quickly; on the other hand, it can reduce the occurrence of substandard electrical products at the source, thereby reducing costs and minimizing personal injury.

[0011] In this invention, the method for evaluating the insulation performance of organic composite solid insulating materials is obtained through a test comprising the following steps:

[0012] S1. Prepare organic composite solid insulating material samples for testing;

[0013] S2. Test the porosity and electrical strength of the sample prepared in step S1;

[0014] S3. Using the porosity obtained in step S2 as the abscissa and the electrical strength as the ordinate, establish a porosity-electrical strength relationship graph, and fit the curve in the relationship graph to obtain the relationship.

[0015] In this invention, step S1 includes the following steps: after mixing the raw materials for preparing the organic composite solid insulating material, vacuum treatment is performed, and the organic composite solid insulating material sample is obtained by curing.

[0016] This invention allows for the preparation of organic composite solid insulating materials with varying porosities by modifying the preparation process, such as vacuuming time, curing temperature, and curing time. Preferably, the vacuuming time is 0-2 hours; the curing temperature is 20-150°C; and the curing time is 2-15 hours.

[0017] Preferably, the raw materials in step S1 include a polymer matrix, a curing agent, and a functional filler.

[0018] Preferably, the polymer matrix is ​​epoxy resin; the curing agent is a commonly used curing agent in the art, specifically including but not limited to aliphatic amines, cyclic amines, aromatic amines, polyamides, and acid anhydrides; the functional filler is a reinforcing filler, specifically silica powder.

[0019] In the organic composite solid insulating material of the present invention, the amount of the functional filler added is 50-60% based on the total weight of the organic composite solid insulating material.

[0020] Preferably, the size of the sample to be tested in step S1 is Ф100mm×1mm (meaning diameter×thickness).

[0021] In this invention, the porosity test in step S2 includes the following steps:

[0022] After drying the sample obtained in step S1 to constant weight, weigh it and record it as m1; then immerse the sample in deionized water at 23℃±2℃ until saturated, wipe the water off the sample surface, and measure the weight of the sample at this point, recording it as m3; immerse the water-saturated sample in water and weigh it, recording it as m2; calculate the porosity K(100%) = V 孔 / V 样 ×100%=(m3-m1) / (m3-m2)×100%.

[0023] Preferably, the drying temperature is 40~60℃, more preferably 50℃.

[0024] In this invention, the electrical strength described in step S2 is tested according to Part 1 (Test under power frequency) of the standard GB / T 1408.1-2016, Electrical Strength Test Method for Insulating Materials, and the test parameters are as follows:

[0025] Test medium: Transformer oil (such as 25# transformer oil);

[0026] Electrode system: Φ25mm / Φ75mm cylindrical electrode system;

[0027] Method of applying voltage: Apply AC voltage at a boost rate of 2kV / s;

[0028] Frequency of applied voltage: 50Hz;

[0029] The test temperature was 23℃±2℃.

[0030] Test pressure: 1 ± 0.02 atm.

[0031] Preferably, the polymer matrix is ​​epoxy resin.

[0032] Preferably, the number-average molecular weight M of the polymer matrix is ​​100,000 to 250,000 g / mol.

[0033] When the above-mentioned relationship of the present invention is applied to the calculation of the electrical strength of organic composite solid insulating materials, the error between the electrical strength of the organic composite solid insulating materials calculated according to the relationship and the actual electrical strength is <5.5%.

[0034] The evaluation method of the present invention can also be applied to the following conditions:

[0035] (1) The number average molecular weight M of the polymer matrix is ​​100,000~150,000 g / mol. When the porosity is <3.5%, the insulation performance of the organic composite solid insulating material is deemed qualified.

[0036] (2) The number average molecular weight M of the polymer matrix is ​​150,000~200,000 g / mol. When the porosity is <2.5%, the insulation performance of the organic composite solid insulating material is deemed qualified.

[0037] (3) The number average molecular weight M of the polymer matrix is ​​200,000~250,000 g / mol. When the porosity is <1.7%, the insulation performance of the organic composite solid insulating material is deemed qualified.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] The evaluation method of this invention starts with organic composite solid insulating materials. By testing the porosity and electrical properties of these materials, a correlation is established between porosity and the insulation performance (especially electrical strength) of the organic composite solid insulating materials. Using this evaluation method, on the one hand, the insulation performance of organic composite solid insulating materials can be assessed simply and quickly; on the other hand, it can reduce the occurrence of substandard electrical products at the source, thereby reducing costs and minimizing personal injury. Attached Figure Description

[0040] Figure 1 The graph shows the relationship between porosity and electrical strength of the insulating material obtained by fitting the organic composite solid insulating material of Example 1. Detailed Implementation

[0041] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0042] Example 1

[0043] This embodiment provides a method for evaluating the insulation performance of organic composite solid insulating materials, including the following steps:

[0044] S1. Preparation of organic composite solid insulating material samples for testing:

[0045] One part by weight of epoxy resin (bisphenol A type epoxy resin, number average molecular weight of 100,000 g / mol, obtained by GPC test, referring to standard QJ 1870-90; epoxy value of 4.4~5.0 Eg / kg; flash point of about 150℃), one part by weight of curing agent (LH9218, purchased from Shanghai Wenyou Industrial Co., Ltd.), and three parts by weight of silica powder (particle size of 35μm, purchased from Shanghai Wenyou Industrial Co., Ltd.) were added to a high-speed mixer and mixed evenly (30 min). The mixed raw material was then poured into a mold, vacuumed, and then cured at high temperature. The curing procedure is shown in Table 1.

[0046] Table 1 Curing procedures for different samples

[0047]

[0048] After complete curing, a test sample with dimensions of Ф100mm×1mm was obtained. Three test samples were prepared according to this method and labeled as 1-1, 1-2, and 1-3, respectively.

[0049] S2. The porosity and electrical strength of the three samples obtained in step S1 are tested respectively:

[0050] Porosity: After drying the sample obtained in step S1 to constant weight, weigh it and record it as m1; then immerse the sample in deionized water at 23℃±2℃ until it is saturated (i.e., the sample volume no longer changes within 24 hours), wipe the water off the sample surface, and measure the weight of the sample at this point, recording it as m3; immerse the water-saturated sample in water and weigh it, recording it as m2; calculate the porosity K=V 孔 / V 样 = (m3-m1) / (m3-m2);

[0051] The electrical strength was tested according to Part 1 (Test at Power Frequency) of the standard GB / T 1408.1-2016, Electrical Strength Test Method for Insulating Materials. The test parameters are as follows:

[0052] Test medium: 25# transformer oil;

[0053] Electrode system: Φ25mm / Φ75mm cylindrical electrode system;

[0054] Method of applying voltage: Apply AC voltage at a boost rate of 2kV / s;

[0055] Frequency of applied voltage: 50Hz;

[0056] The test temperature was 23℃±2℃.

[0057] Test pressure: 1 atm.

[0058] The test results of porosity and electrical strength of each sample are shown in Table 2:

[0059] Table 2 shows the test results of porosity and electrical strength of each sample in Example 1.

[0060]

[0061] S3. Based on the test results in Table 2, establish a porosity-electrical strength relationship graph with porosity (X) as the abscissa and the measured electrical strength (Y) as the ordinate (see Table 2). Figure 1 The curve in the relationship graph was fitted to obtain the relationship Y = -2.5211X + 18.856. The porosity was substituted into the formula to calculate the electrical strength Y' of each sample. The electrical strength Y' was compared with the measured electrical strength Y (i.e., the actual electrical strength). The standard deviation of the error (|Y' - Y| / Y*100%, in %) was 0.445.

[0062] Example 2

[0063] This embodiment provides a method for evaluating the insulation performance of organic composite solid insulating materials. The test is performed according to the steps of Example 1, except that the selection of epoxy resin and the preparation process (vacuum time, curing procedure) are different in step S1. See Table 3 for details.

[0064] Table 3. Epoxy resin parameters and curing procedures used to prepare the test samples.

[0065]

[0066] Samples with different porosities were prepared according to the above process; the fitted relationship obtained in step S3 is Y=-2.877X+19.628. The electrical strength Y' of each sample was calculated and compared with the electrical strength Y obtained by testing. The standard deviation of the error (|Y'-Y| / Y*100%, in %) is 0.355 (see Table 4 for detailed test results).

[0067] Table 4 shows the test results of porosity and electrical strength of each sample in Example 2.

[0068]

[0069] Example 3

[0070] This embodiment provides a method for evaluating the insulation performance of organic composite solid insulating materials. The test is performed according to the steps of Example 1, except that the type of epoxy resin and the preparation process (vacuum time, curing procedure) are different in step S1. See Table 5 for details:

[0071] Table 5. Parameters and curing procedures of the epoxy resin used to prepare the test samples.

[0072]

[0073] Samples with different porosities were prepared according to the above process; the fitted relationship obtained in step S3 is Y=-3.2956X+19.895. The electrical strength Y' of each sample was calculated and compared with the measured electrical strength Y. The standard deviation of the error (|Y'-Y| / Y*100%, in %) is 0.850. The test results are shown in Table 6.

[0074] Table 6 shows the test results of porosity and electrical strength of each sample in Example 3.

[0075]

[0076] Example 4

[0077] This embodiment provides a method for evaluating the insulation performance of organic composite solid insulating materials. The test is performed according to the steps of Example 1, except that the selection of epoxy resin and the preparation process (vacuum time, curing procedure) are different in step S1. See Table 7 for details:

[0078] Table 7. Epoxy resin parameters and curing procedures used to prepare the test samples.

[0079]

[0080] Samples with different porosities were prepared according to the above process; the relationship obtained by fitting in step S3 is Y=-3.7234X+18.382. The electrical strength Y' of each sample was calculated and compared with the electrical strength Y obtained by testing. The standard deviation of the error (|Y'-Y| / Y*100%, in %) is 0.035. The test results are shown in Table 8.

[0081] Table 8 shows the test results of porosity and electrical strength of each sample in Example 4.

[0082]

[0083] Example 5

[0084] This embodiment provides a method for evaluating the insulation performance of organic composite solid insulating materials. The test is performed according to the steps of Example 1, except that the selection of epoxy resin and the preparation process (vacuum time, curing procedure) are different in step S1. See Table 9 for details.

[0085] Table 9. Epoxy resin parameters and curing procedures used to prepare the test samples.

[0086]

[0087] Samples with different porosities were prepared according to the above process; the relationship obtained by fitting in step S3 is Y=-6.1914X+20.061. The electrical strength Y' of each sample was calculated and compared with the electrical strength Y obtained by testing. The standard deviation of the error (|Y'-Y| / Y*100%, in %) is 1.361. The test results are detailed in Table 10.

[0088] Table 10 shows the test results of porosity and electrical strength of each sample in Example 5.

[0089]

[0090] Example 6

[0091] This embodiment provides a method for evaluating the insulation performance of organic composite solid insulating materials. The test is conducted according to the steps of Example 1. The difference from Example 1 is that in step S1, the type of epoxy resin is replaced with phenolic epoxy resin with a number average molecular weight of 100,000 g / mol. In step S3, the fitted formula is Y = -2.5208X + 18.435. The electrical strength Y' of each sample is calculated and compared with the electrical strength Y obtained from the test. The standard deviation of the error (|Y' - Y| / Y*100%, in %) is 0.757. The test results are detailed in Table 11.

[0092] Table 11 shows the test results of porosity and electrical strength of each sample in Example 6.

[0093]

[0094] The results of Examples 1-6 show that the intercept terms in the formulas for different epoxy resin composite solid insulating materials are all within the range of 19±2, which can be considered as normal fluctuations. However, the slopes of the solid insulating materials prepared by different epoxy resins show significant fluctuations. The only difference between Examples 1 and 6 is the type of epoxy resin, while the molecular weight is the same. The slopes in the fitted curve equations are also similar, indicating that there is a significant correlation between the slope value in the curve equation and the molecular weight of the epoxy resin. Therefore, the relationship between the slope value in the curve equation and the molecular weight of the epoxy resin was further obtained. Finally, it was substituted into the fitting formula for the porosity and electrical strength of the solid insulating materials prepared by the above six epoxy resins with different molecular weights, resulting in Y=-[(M / 100000×2.52)±0.005]X+(19±2).

[0095] Application examples

[0096] Following the sample preparation methods described in Examples 1-6 above, 100 samples of each type were prepared. The electrical pass rate (A (%) = number of qualified samples / total number of samples * 100%) of these samples was then tested according to GB / T 19519-2014. When the pass rate A < 5%, the insulating material was considered qualified and could be used to manufacture electrical products. This application yielded the following conclusions:

[0097] (1) The number average molecular weight M of the polymer matrix is ​​100,000~150,000 g / mol. When the porosity is <3.5%, the insulation performance of the organic composite solid insulating material is deemed qualified.

[0098] (2) The number average molecular weight M of the polymer matrix is ​​150,000~200,000 g / mol. When the porosity is <2.5%, the insulation performance of the organic composite solid insulating material is deemed qualified.

[0099] (3) The number average molecular weight M of the polymer matrix is ​​200,000~250,000 g / mol. When the porosity is <1.7%, the insulation performance of the organic composite solid insulating material is deemed qualified.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for evaluating the insulation performance of organic composite solid insulating materials, characterized in that, Perform the test according to the following steps: S1. Prepare organic composite solid insulating material samples for testing; S2. Test the porosity and electrical strength of the sample prepared in step S1; S3. Using the porosity obtained in step S2 as the abscissa and the electrical strength as the ordinate, establish a porosity-electrical strength relationship graph, and fit the curve in the graph to obtain the following relationship: Y=-[(M / 100000×2.52)±0.005]X+(19±2) Wherein, Y is the electrical strength of the organic composite solid insulating material, in kV / mm; M is the number-average molecular weight of the polymer matrix in the organic composite solid insulating material, in g / mol; and X is the porosity of the organic composite solid insulating material, in units of %.

2. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 1, characterized in that, Step S1 includes the following steps: after mixing the raw materials for preparing the organic composite solid insulation material, vacuum treatment is performed, and the organic composite solid insulation material sample is obtained after curing.

3. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 1, characterized in that, The porosity K in step S2 is calculated using the following formula: K = V 孔 / V 样 ×100%.

4. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 3, characterized in that, The porosity K test includes the following steps: After drying the sample obtained in step S1 to constant weight, weigh it and record it as m1; then immerse the sample in deionized water at 23℃±2℃ until saturated, wipe the water off the sample surface, and measure the weight of the sample at this point, recording it as m3; immerse the water-saturated sample in water and weigh it, recording it as m2; finally, calculate the porosity K=V 孔 / V 样 ×100%=(m3-m1) / (m3-m2)×100%.

5. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 1, characterized in that, The electrical strength mentioned in step S2 is obtained according to the standard GB / T 1408.1-2016, and the test parameters are as follows: Test medium: Transformer oil; Electrode system: Φ25mm / Φ75mm cylindrical electrode system; Method of applying voltage: Apply AC voltage at a boost rate of 2kV / s; Frequency of applied voltage: 50Hz; The test temperature was 23℃±2℃. Test pressure: 1 ± 0.02 atm.

6. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 1, characterized in that, The polymer matrix is ​​epoxy resin.

7. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 1, characterized in that, The number-average molecular weight M of the polymer matrix is ​​100,000 to 250,000 g / mol.

8. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 1, characterized in that, The error between the electrical strength of the organic composite solid insulating material calculated according to the above formula and the actual electrical strength is less than 5.5%.

9. The method for evaluating the insulation performance of organic composite solid insulating materials according to claim 1, characterized in that, It also satisfies at least one of the following conditions: (1) The number average molecular weight M of the polymer matrix is ​​100,000~150,000 g / mol. When the porosity is <3.5%, the insulation performance of the organic composite solid insulating material is deemed qualified. (2) The number average molecular weight M of the polymer matrix is ​​150,000~200,000 g / mol. When the porosity is <2.5%, the insulation performance of the organic composite solid insulating material is deemed qualified. (3) The number average molecular weight M of the polymer matrix is ​​200,000~250,000 g / mol. When the porosity is <1.7%, the insulation performance of the organic composite solid insulating material is deemed qualified.

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