Method for testing voltage tolerance index of insulating silicone rubber material

Abstract

The invention discloses a method for testing the voltage tolerance index of an insulating silicone rubber material, and relates to the technical field of cable detection, and the method comprises the following steps: preparing an SIR test sample and a test electrode based on test requirements; screening test oil; placing the SIR test sample in the test oil, and carrying out a step-by-step boost test on the SIR test sample based on the test electrode to obtain test data; calculating the test data based on the damage matrix and standardized variance fitting to obtain the voltage tolerance index of the SIR test sample; by using the damage matrix and variance processing, measurement errors caused by electrode vibration in an alternating current withstand voltage test can be avoided to the greatest extent, the accuracy of a voltage withstand index is ensured, the withstand voltage test efficiency of the SIR insulating material is remarkably improved, and meanwhile, the reliability of a withstand voltage test result is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of cable detection, in particular to a voltage tolerance index testing method for an insulating silicone rubber material. Background Art

[0002] Silicone rubber (SIR) is the main insulating material widely used in AC cable connectors, which directly affects the service life of the connector and the reliability of the cable system. Therefore, dielectric strength testing of SIR materials under AC voltage is of great significance for obtaining key material parameters and optimizing cable insulation structure.

[0003] Currently, there are methods to obtain the short-term and long-term withstand voltage performance of cross-linked polyethylene (XLPE) insulation materials and the rapid breakdown characteristics of the XLPE / SIR interface from different angles. However, these methods are not applicable to the voltage withstand index test of SIR materials for cable joints and have great limitations. Due to the differences in material properties, when the XLPE material test method is applied to SIR materials for testing, it is impossible to obtain effective data to characterize the long-term withstand voltage performance of SIR materials. Therefore, it is urgent to provide a test method suitable for studying the long-term voltage withstand capability of SIR materials, so as to achieve accurate measurement of the dielectric parameters of SIR materials for AC cable joint insulation.

[0004] Chinese patent, publication number: CN118362846A, publication date: July 19, 2024, discloses a withstand voltage detection device for transformer materials for electric energy meters, including: an AC withstand voltage test instrument is connected to two test terminals, and an insulation distance for testing is formed between the second test position and the first test position of the transformer material test assembly, and multiple second test positions correspond to multiple insulation distances; during the test, the transformer material is connected to a test terminal at the first test position, and the transformer material is connected to another test terminal at the second test position. After the wiring is completed, the AC withstand voltage test instrument is operated to perform a withstand voltage test on the transformer material and observe the test phenomenon. This scheme mainly tests the minimum insulation distance of the transformer material to perform a withstand voltage test on the transformer material. The device cannot be used for withstand voltage testing of the SIR main insulation material commonly used in AC cable connectors.

[0005] Chinese patent, publication number: CN104239728A, publication date: December 24, 2014, discloses a method for estimating the steep wave voltage tolerance margin of a composite insulator, which calculates the electric field strength of the two parts of the composite insulator with the largest electric field when the composite insulator is subjected to steep wave voltage based on the average flashover voltage of the composite insulator obtained in the test and the geometric dimensions of the composite insulator, and compares it with the interface withstand voltage related to the composite insulator manufacturing process, so as to estimate the steep wave voltage tolerance margin of the composite insulator. However, the test process of this scheme is too complicated, and it is necessary to calculate cumbersome data, which makes the test efficiency low. In addition, there is a lack of control over the various test parameters of the test environment, and it is difficult to control the damage caused by the voltage to the insulating material during the test, and the applicability is poor. Summary of the invention

[0006] The invention aims at the problem that conventional insulating material withstand voltage test methods have low applicability and cannot efficiently and accurately obtain the dielectric parameters of cable joints; a voltage tolerance index test method for insulating silicone rubber materials is proposed, by preparing SIR test samples, test electrodes and test oil according to test requirements, placing the SIR test samples in the test oil and performing a step-by-step voltage boost test on them through the test electrodes, obtaining test data, and calculating a damage matrix and a standardized variance according to the test data to determine the voltage tolerance index of the SIR test samples, by utilizing the damage matrix and variance processing to avoid measurement errors caused by electrode vibration in an AC withstand voltage test to the greatest extent, ensuring the accuracy of the voltage tolerance index, significantly improving the efficiency of the SIR insulating material withstand voltage test and ensuring the reliability of the withstand voltage test results.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for testing the voltage tolerance index of an insulating silicone rubber material, comprising the following steps: Prepare SIR test samples and test electrodes based on test requirements; Screening test oil; The SIR test sample is placed in the test oil, and a step-by-step voltage boost test is performed on it based on the test electrode to obtain test data; the test data is calculated based on the damage matrix and the standardized variance fitting to obtain the voltage tolerance index of the SIR test sample.

[0008] In this scheme, by screening the test oil, the swelling phenomenon and performance change of the sample can be avoided, ensuring the accurate measurement of the voltage tolerance index of the SIR sample; through the step-by-step voltage boost breakdown test method, the breakdown of the SIR sample at different voltages can be clearly understood, so as to obtain more comprehensive test data and ensure the reliability of the final voltage tolerance index calculation results; through damage matrix and variance processing, the thickness change of the sample caused by electrode vibration, which leads to the problem of thickness measurement error, can be avoided to the greatest extent, ensuring the accuracy, reliability and efficiency of the voltage tolerance index.

[0009] Preferably, the preparation of the test sample and the test electrode environment based on the test requirements includes: Square or round SIR sheet specimens with uniform thickness are used as SIR test samples after secondary sulfurization, and test electrodes are made based on standard size electrodes.

[0010] Preferably, the SIR flake sample comprises: A square SIR sheet-like specimen whose side length meets the first threshold interval; or, A circular SIR flake specimen having a thickness within the second threshold interval and a diameter within the first threshold interval.

[0011] Preferably, the screening test oil comprises the following sub-steps: According to the swelling effect characteristics of SIR, insulating oil with lower swelling effect than SIR is selected as the test oil.

[0012] Preferably, the screening test oil further comprises: Randomly selecting a plurality of samples based on the SIR test sample, and obtaining a first mass of the plurality of samples, wherein the first mass represents an average mass of the plurality of samples; Immersing multiple samples in the candidate oil, applying a first breakdown voltage to the multiple samples according to the test electrode to perform a breakdown electric shock test, and obtaining a second mass of the multiple samples after the test, wherein the second mass represents an average mass of the multiple samples after the test, wherein the first breakdown voltage ranges from [30%, 50%]; The mass change rate of the plurality of test pieces is calculated based on the first mass and the second mass, and the test oil is determined according to the mass change rate.

[0013] Preferably, the step-by-step voltage boost test is performed on the test electrode to obtain test data, including: Applying several levels of second breakdown voltage to several of the SIR test samples in the test oil based on the test electrode; A time-limited breakdown electric shock test is performed on the SIR test sample based on the second breakdown voltage to obtain test data.

[0014] Preferably, the level of the second breakdown voltage increases step by step according to set time steps and voltage steps.

[0015] Preferably, the calculation of the test data based on the damage matrix and variance fitting to obtain the voltage tolerance index of the SIR test sample includes: Calculate the aging accumulation of a single SIR test sample based on the test data; Establishing a damage matrix corresponding to the step-by-step voltage boost breakdown test based on the accumulated aging amount of each of the SIR test samples; A standardized variance value is calculated based on the damage matrix, and a voltage tolerance index of the SIR test sample is obtained based on the standardized variance value.

[0016] Preferably, the calculation formula of the aging accumulation amount is as follows: Where D represents the cumulative amount of AC aging of the sample, t k represents the time step / s, w represents the withstand voltage level, E j It represents the electric field strength value of each level that has been subjected to the complete time step / kV·mm-1, n represents the voltage tolerance index, t f Indicates the duration of the final electric field / s, E f represents the final electric field strength value / kV·mm-1, E0 represents the initial electric field strength value / kV·mm-1, k v1 It indicates the voltage increasing rate from zero to the starting voltage, d indicates the sample thickness / mm, k v2 Indicates the voltage increase rate between each voltage level.

[0017] Preferably, determining the voltage tolerance index of the SIR test sample based on the standardized variance value comprises: A plurality of variance values ​​are calculated with the goal of minimizing the standardized variance value, and the voltage tolerance index corresponding to the minimum standardized variance value is used as the voltage tolerance index of the SIR test sample.

[0018] Beneficial effects of the present invention: 1. Through the optimization of electrode structure and the screening of test oil, the test data abnormality caused by the bending deformation of SIR specimens and the swelling with the test insulating oil is avoided, ensuring the accuracy and reliability of the test results; 2. The SIR test samples are subjected to a time-limited step-by-step voltage test through the time step and the voltage step, which avoids the data being incompatible with the long-time withstand voltage test when the test time is too short, and the data deviation caused by the accumulation of thermal effects when the test time is too long, further ensuring the accuracy of the test results; 3. This application can be expanded to evaluate the long-term voltage tolerance capability of SIR materials used for insulation of AC cable joints at any operating frequency and any voltage level, thereby improving the adaptability of the test method. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. Also, the same reference symbols are used throughout the drawings to represent the same parts.

[0020] Figure 1 This is a flow chart of a voltage tolerance index testing method for an insulating silicone rubber material of this embodiment.

[0021] Figure 2 The present invention is a flow chart of a voltage tolerance index test of an AC cable connector insulation SIR material according to a specific embodiment.

[0022] Figure 3 It is a schematic diagram of the overall structure of an electrode according to a specific embodiment.

[0023] Figure 4 The figure is a schematic diagram of the circuit principle of a step-by-step voltage boost test of a specific embodiment. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Example 1: Figure 1 As shown, a method for testing the voltage tolerance index of an insulating silicone rubber material comprises the following steps: Prepare SIR test samples and test electrodes based on test requirements; Screening test oil; The SIR test sample is placed in the test oil, and a step-by-step voltage boost test is performed on it based on the test electrode to obtain test data; the test data is calculated based on the damage matrix and the standardized variance fitting to obtain the voltage tolerance index of the SIR test sample.

[0026] Specifically, the preparation of the test sample and the test electrode environment based on the test requirements includes: Square or round SIR sheet specimens with uniform thickness are used as SIR test samples after secondary sulfurization, and test electrodes are made based on standard size electrodes.

[0027] Furthermore, the diameter of the standard size electrode pair is 25 mm, and there is a supporting platform near the lower electrode that is flush with the electrode and has a large enough area to prevent the sample from bending and deforming.

[0028] In this embodiment, after the SIR thin sheet sample is subjected to secondary vulcanization treatment, the dielectric properties of the SIR thin sheet sample will be improved, and the change of dielectric strength with withstand voltage time will be more significant, which is more conducive to obtaining the voltage withstand index. The secondary vulcanization treatment process can be flexibly selected according to the user's test conditions, such as baking in a high temperature oven at 120℃ to 200℃ for 0.5 to 2h.

[0029] Specifically, the SIR flake sample comprises: A square SIR sheet-like specimen whose side length meets the first threshold interval; or, A circular SIR flake specimen having a thickness within the second threshold interval and a diameter within the first threshold interval.

[0030] In this embodiment, it is recommended that the first threshold interval is [100 mm, 200 mm] and the second threshold interval is [0.5 mm, 2.0 mm], and the thickness of the SIR thin sheet sample is required to be uniform, which ensures the consistency of the test conditions and improves the accuracy and comparability of the test.

[0031] Specifically, the screening test oil comprises the following sub-steps: According to the swelling effect characteristics of SIR, insulating oil with lower swelling effect than SIR is selected as the test oil.

[0032] It is understandable that by selecting insulating oil that has no obvious swelling effect with SIR as the test oil, the influence of external factors on the test results is avoided, making the test results more real and reliable. For example, using FR3 vegetable oil or silicone oil with a viscosity of 12500 (no heating requirement) can avoid the interference of insulating oil on the performance of SIR samples and ensure the accuracy of test results.

[0033] Specifically, the screening test oil also includes: Randomly selecting a plurality of samples based on the SIR test sample, and obtaining a first mass of the plurality of samples, wherein the first mass represents an average mass of the plurality of samples; Immersing multiple samples in the candidate oil, applying a first breakdown voltage to the multiple samples according to the test electrode to perform a breakdown electric shock test, and obtaining a second mass of the multiple samples after the test, wherein the second mass represents an average mass of the multiple samples after the test, wherein the first breakdown voltage ranges from [30%, 50%]; The mass change rate of the plurality of test pieces is calculated based on the first mass and the second mass, and the test oil is determined according to the mass change rate.

[0034] Specifically, the calculation formula of the mass change rate is as follows: Where η represents the mass change rate, m t It represents the second mass of multiple samples after the breakdown voltage is applied for t time, and m0 represents the first mass of multiple samples.

[0035] As an implementation method, randomly select 3 samples, weigh the sample mass with a balance, immerse the sample in the alternative oil, apply 30%-50% of the expected short-time breakdown voltage to the sample, during which the sample does not breakdown or flashover, maintain the voltage for 1-2 hours, remove the sample, take out and wipe it clean, weigh the sample mass again, if the mass change rate before and after the voltage test is less than 1%, the oil can be used for the test.

[0036] In this embodiment, 30%-50% of the expected short-time breakdown voltage is applied to the sample in order to simulate the voltage level that may be encountered in the actual working environment, while not causing the sample to immediately break down or flash over; during the process of applying the voltage, it is maintained for 1-2 hours to facilitate the observation of the stability of the sample under the combined action of the alternative oil and the voltage; through this method, the insulating oil that has no obvious swelling effect on the SIR sample can be screened out to ensure the accuracy of the test results. Because if the alternative oil has a significant swelling effect on the SIR sample, it may change the physical and chemical properties of the sample, thereby affecting the reliability of the test results. By controlling the mass change rate to less than 1%, the influence of external factors on the test results can be further reduced, which helps to more accurately evaluate the voltage tolerance performance of the SIR sample.

[0037] Specifically, the step-by-step voltage boost test is performed on the test electrode to obtain test data, including: Applying several levels of second breakdown voltage to several of the SIR test samples in the test oil based on the test electrode; A time-limited breakdown electric shock test is performed on the SIR test sample based on the second breakdown voltage to obtain test data.

[0038] Specifically, the level of the second breakdown voltage increases step by step according to the set time step and voltage step.

[0039] As an implementation method, a number of samples are taken, placed in test oil, and a step-by-step voltage increase test is performed. 50%-70% of the expected short-time breakdown voltage is applied to the sample as the starting first-level voltage, and the voltage is increased step by step according to a certain time step and voltage step until the sample breaks down. For example, the voltage step is 0.5-1kV, and the time step is 120s, 360s, and 900s respectively, and it is required that the breakdown of the sample occurs at level 6 or above and the total withstand voltage time does not exceed 3 hours in each test.

[0040] In this embodiment, through the step-by-step voltage boost test, the voltage applied to the SIR sample can be gradually increased to observe its performance at different voltage levels, thereby evaluating its voltage tolerance performance; wherein, it is required that the sample breakdown occurs at level 6 or above and the total withstand voltage time does not exceed 3 hours in each test, which can ensure that the sample receives sufficient voltage stimulation for a sufficiently long time, thereby more accurately evaluating its voltage tolerance performance. At the same time, it also avoids errors caused by too long a test time or insufficient voltage stimulation. The recommended voltage step is 0.5-1kV, and the time step is 120s, 360s, and 900s, respectively. The settings of these parameters can be adjusted according to the characteristics of the sample and the test requirements, thereby optimizing the test process. By step-by-step voltage boosting, multiple sample tests can be completed in a shorter time, thereby improving the test efficiency. Since each voltage boost is based on the voltage level of the previous level, controlling the voltage to increase step by step can avoid sample damage or test failure caused by voltage mutations.

[0041] The time step and voltage step can be set adaptively according to the user's test conditions, which improves the adaptability of the test method. In addition, reasonable voltage step and time step can ensure that the sample has enough adaptation time during the step-by-step voltage increase process, and can also reduce test time and cost.

[0042] Specifically, the calculation of the test data based on the damage matrix and variance fitting to obtain the voltage tolerance index of the SIR test sample includes: Calculate the aging accumulation of a single SIR test sample based on the test data; Establishing a damage matrix corresponding to the step-by-step voltage boost breakdown test based on the accumulated aging amount of each of the SIR test samples; A standardized variance value is calculated based on the damage matrix, and a voltage tolerance index of the SIR test sample is obtained based on the standardized variance value.

[0043] Specifically, the calculation formula of the aging accumulation amount is as follows: Where D represents the cumulative amount of AC aging of the sample, t k represents the time step / s, w represents the withstand voltage level, Ej It represents the electric field strength value of each level that has been subjected to the complete time step / kV·mm-1, n represents the voltage tolerance index, t f Indicates the duration of the final electric field / s, E f represents the final electric field strength value / kV·mm-1, E0 represents the initial electric field strength value / kV·mm-1, k v1 It indicates the voltage increasing rate from zero to the starting voltage, d indicates the sample thickness / mm, k v2 Indicates the voltage increase rate between each voltage level.

[0044] The damage matrix Λ is expressed as follows: In this embodiment, by constructing a damage matrix, a more in-depth and comprehensive evaluation of the voltage tolerance performance of the sample can be performed. For example, it can be observed whether the aging accumulation D of the sample shows an increasing trend as the voltage increases, thereby judging whether the performance of the sample gradually decreases, which helps to compare the performance of different samples under the same conditions.

[0045] Specifically, determining the voltage tolerance index of the SIR test sample based on the standardized variance value includes: A plurality of variance values ​​are calculated with the goal of minimizing the standardized variance value, and the voltage tolerance index corresponding to the minimum standardized variance value is used as the voltage tolerance index of the SIR test sample.

[0046] Specifically, the standardized variance value calculation formula is as follows: In the formula, σ represents the standardized variance, represents the average value of the aging accumulation of each column of the damage matrix, v represents the column of the damage matrix, u represents the row of the damage matrix, i represents the row element of each row in the damage matrix, and j represents the column element of each column in the damage matrix.

[0047] In this embodiment, the degree of proximity of the aging accumulation amount D is described by the standardized variance σ, and the value of n that minimizes σ is found to be the desired voltage tolerance index.

[0048] Embodiment 2, as Figure 2 As shown in the figure, the test process of measuring the voltage withstand index of the insulation SIR material of the AC cable connector using this scheme is as follows: Step 1: Prepare a SIR sheet specimen by injection molding using Wacker 745 two-component liquid silicone rubber, with a size of 100 mm × 100 mm and a thickness of (0.94 ± 0.02) mm. The secondary vulcanization temperature is 120 ° C and the time is 2 hours; Step 2: Make ball-cylindrical electrodes with a diameter of 25 mm. The upper electrode is a ball electrode and the lower electrode is a cylindrical electrode. There is a circle of resin platforms of equal height or slightly lower around the cylinder to prevent the SIR sample from bending and deforming during the test, which may lead to deviation of the results. Figure 3 As shown; Step 3: Select 4 test oils (including transformer oil, 100 viscosity silicone oil, 12500 viscosity silicone oil and FR3 vegetable oil) for oil selection test to obtain the quality change rate. The specific data are shown in Table 1. Table 1 Statistics of four test oils It can be seen from Table 1 that FR3 vegetable oil and silicone oil with a viscosity of 12500 meet the oil selection criteria. Considering the influence of mass change rate and viscosity, FR3 vegetable oil was selected for subsequent tests; Step 4: Figure 4 As shown, 15 random samples were immersed in the test insulating oil, and a voltage of 14.6 kV (short-time breakdown field strength is about 25.6 kV / mm) with a frequency of 20 Hz was applied to the samples. The voltage step was 0.5 kV, and the time steps were 120 s, 360 s, and 900 s respectively for step-by-step voltage boosting test. The test data are shown in Table 2. Table 2 Test data statistics Step 5: Based on 15 sets of test data, using Formula 2, Formula 3, Formula 4 and Formula 5, the voltage tolerance index of the SIR sample under 20 Hz voltage is obtained to be 16.55.

[0049] Beneficial effects of the embodiment: By optimizing the electrode structure and screening the test oil, the test data anomalies caused by the bending deformation of the SIR sample and the swelling with the test insulating oil are avoided, ensuring the accuracy and reliability of the calculation results of the voltage tolerance index of the SIR sample. Through the step-by-step breakdown test method, the breakdown of the SIR sample at different voltages can be clearly understood, so as to obtain more comprehensive test data and ensure the reliability of the final calculation results of the voltage tolerance index; wherein, the SIR test sample is subjected to a time-limited step-by-step step-by-step test through the time step and the voltage step, which avoids the data being not equivalent to the long-time withstand voltage test when the test time is too short, and the data deviation caused by the accumulation of thermal effects when the test time is too long, further ensuring the accuracy of the test results. Through damage matrix and variance processing, the problem of thickness measurement error caused by the change of sample thickness due to electrode vibration can be avoided to the greatest extent, ensuring the accuracy, reliability and efficiency of the voltage tolerance index. In addition, the present application can be extended to the long-term voltage tolerance capacity evaluation of SIR materials for insulation of AC cable joints at any operating frequency and any voltage level, improving the adaptability of the test method.

[0050] The above specific embodiments are preferred embodiments of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the present specific embodiments. All equivalent changes made in accordance with the shape, structure, and method of the present invention are within the protection scope of the present invention.

Claims

1. A method for testing the voltage tolerance index of an insulating silicone rubber material, characterized in that: The steps include: Prepare SIR test samples and test electrodes based on test requirements; Screening test oil; The SIR test sample is placed in the test oil, and a step-by-step pressure test is performed on it based on the test electrode to obtain test data; The test data is calculated based on the damage matrix and the standardized variance fitting to obtain the voltage tolerance index of the SIR test sample.

2. The voltage tolerance index testing method of an insulating silicone rubber material according to claim 1, characterized in that: The method of preparing the test sample and the test electrode environment based on the test requirements includes: Square or round SIR sheet specimens with uniform thickness are used as SIR test samples after secondary sulfurization, and test electrodes are made based on standard size electrodes.

3. The voltage tolerance index testing method of an insulating silicone rubber material according to claim 2, characterized in that: The SIR flake specimen comprises: A square SIR sheet-like specimen whose side length meets the first threshold interval; or, A circular SIR flake specimen having a thickness within the second threshold interval and a diameter within the first threshold interval.

4. The voltage tolerance index testing method of an insulating silicone rubber material according to claim 1, characterized in that: The screening test oil comprises the following sub-steps: According to the swelling effect characteristics of SIR, insulating oil with lower swelling effect than SIR is selected as the test oil.

5. The voltage tolerance index testing method of an insulating silicone rubber material according to claim 3, characterized in that: The screening test oil also includes: Randomly selecting a plurality of samples based on the SIR test sample, and obtaining a first mass of the plurality of samples, wherein the first mass represents an average mass of the plurality of samples; Immersing multiple samples in the candidate oil, applying a first breakdown voltage to the multiple samples according to the test electrode to perform a breakdown electric shock test, and obtaining a second mass of the multiple samples after the test, wherein the second mass represents an average mass of the multiple samples after the test, wherein the first breakdown voltage ranges from [30%, 50%]; The mass change rate of the plurality of test pieces is calculated based on the first mass and the second mass, and the test oil is determined according to the mass change rate.

6. The voltage tolerance index testing method of an insulating silicone rubber material according to claim 1, characterized in that: The step-by-step voltage boost test is performed on the test electrode to obtain test data, including: Applying several levels of second breakdown voltage to several of the SIR test samples in the test oil based on the test electrode; A time-limited breakdown electric shock test is performed on the SIR test sample based on the second breakdown voltage to obtain test data.

7. A method for testing the voltage tolerance index of an insulating silicone rubber material according to claim 6, characterized in that: The level of the second breakdown voltage increases step by step according to the set time step and voltage step.

8. The voltage tolerance index testing method of an insulating silicone rubber material according to claim 7, characterized in that: The test data is calculated based on the damage matrix and the standardized variance fitting to obtain the voltage tolerance index of the SIR test sample, including: Calculate the aging accumulation of a single SIR test sample based on the test data; Establishing a damage matrix corresponding to the step-by-step voltage boost breakdown test based on the accumulated aging amount of each of the SIR test samples; A standardized variance value is calculated based on the damage matrix, and a voltage tolerance index of the SIR test sample is obtained based on the standardized variance value.

9. A method for testing the voltage tolerance index of an insulating silicone rubber material according to claim 8, characterized in that: The calculation formula of the aging accumulation is as follows: Where D represents the cumulative amount of AC aging of the sample, t k represents the time step / s, w represents the withstand voltage level, E j It represents the electric field strength value of each level that has been subjected to the complete time step / kV·mm-1, n represents the voltage tolerance index, t f Indicates the duration of the final electric field / s, E f represents the final electric field strength value / kV·mm-1, E0 represents the initial electric field strength value / kV·mm-1, k v1 It indicates the voltage increasing rate from zero to the starting voltage, d indicates the sample thickness / mm, k v2 Indicates the voltage increase rate between each voltage level.

10. The voltage tolerance index testing method of an insulating silicone rubber material according to claim 8, characterized in that: Determining a voltage tolerance index of the SIR test sample based on the standardized variance value includes: A plurality of variance values ​​are calculated with the goal of minimizing the standardized variance value, and the voltage tolerance index corresponding to the minimum standardized variance value is used as the voltage tolerance index of the SIR test sample.

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