Insulation voltage resistance life evaluation method

Abstract

The application provides an insulation voltage endurance life evaluation method, which comprises the following steps: firstly, obtaining the values of parameters n and lgB through a dynamic voltage breakdown test or a static voltage breakdown test; secondly, obtaining a Weibull modulus under the dynamic voltage breakdown test or the static voltage breakdown test by using Weibull fitting, and calculating a related parameter m; and finally, calculating the relationship between a breakdown probability P and a time t of a material or a device to be tested when a voltage V is applied by using an equation lgt = [(n-2) / m]xlg[-ln(1-P)]+lgB-lg[Γ(1+(n-2) / m)]-nlgV, so that the insulation voltage endurance life of the material or the device to be tested can be evaluated.

Description

Technical Field

[0001] This invention belongs to the field of insulation withstand voltage testing, and in particular relates to a method for evaluating insulation withstand voltage life. Background Technology

[0002] The power and electronics industries utilize numerous materials and devices that perform insulation and withstand voltage functions, such as high-voltage insulators in high-voltage transmission systems, numerous capacitors integrated into electrical appliances, and diodes. These components must withstand certain voltage values ​​during use without breakdown. If the materials and devices cannot withstand the applied voltage, breakdown will occur. The resulting instantaneous high current often causes irreversible damage and destruction to the materials and devices, leading to complete failure and ultimately paralyzing the entire power or electronic system. Furthermore, it is crucial to correctly select materials and devices with appropriate withstand voltage properties; otherwise, product costs will increase or product quality will decline. Therefore, insulation withstand voltage testing of materials and devices is essential for the research, production, and application of insulation withstand voltage materials and devices.

[0003] Currently, insulation withstand voltage testing of materials or devices mainly involves applying a uniformly increasing voltage at a constant rate until breakdown occurs. The voltage at breakdown is defined as the voltage level the material or device can withstand, i.e., the breakdown voltage. Multiple insulation withstand voltage tests are performed on the material or device to obtain multiple breakdown voltage data; the average of these data is defined as the average breakdown voltage of the material or device. The industry often uses the average breakdown voltage as an evaluation index for the insulation withstand voltage level of materials or devices. During design, the average breakdown voltage is used as a standard, combined with engineering design factors, for material or device selection. In studies of the insulation withstand voltage level of materials or devices, statistical analysis of the breakdown voltage data is often performed to analyze the probability distribution of the breakdown voltage. The most common method is to fit the breakdown voltage data to a Weibull distribution to analyze the breakdown probability of the material or device under different voltages.

[0004] However, in practical applications, it has been found that when the applied voltage is much lower than the average breakdown voltage, the breakdown probability of materials and devices often increases with the length of time they are in use. Therefore, using the average breakdown voltage method to evaluate the performance of materials and devices used for extended periods is clearly not suitable. In recent years, the development of power and electronic technologies has placed higher demands on system lifespan. The traditional method of using the average breakdown voltage as an indicator of insulation withstand voltage level can no longer meet the current needs of power and electronic technologies for evaluating the withstand voltage level of materials and devices operating for extended periods. There is an urgent need to establish a method for evaluating the change in the breakdown probability of materials and devices with applied voltage and time—that is, an insulation withstand voltage life evaluation method—to guide the design, application, and development of materials and devices. Summary of the Invention

[0005] In view of this, the present invention proposes a new method for evaluating insulation withstand voltage lifetime. This method can obtain the law of change of the breakdown probability of materials and devices with applied voltage and time, and use this law to evaluate the insulation withstand voltage lifetime of materials or devices.

[0006] To achieve this objective, the present invention adopts the following technical solution: a method for evaluating insulation withstand voltage life, the method comprising:

[0007] S-11: Conduct multiple voltage breakdown tests at different voltage boost rates v, and obtain the average breakdown voltage V of the material or device under test at each voltage boost rate. b ;

[0008] S-12: with average breakdown voltage V b logarithm lgV b Plotting the voltage rise rate data and the average breakdown voltage data in S-11 with the logarithm of the voltage rise rate v (lgv) as the ordinate, and performing linear fitting on the voltage rise rate data and average breakdown voltage data, we obtain the fitted straight line.

[0009] S-13: Calculate the slope η1 of the data fitting line, taking the parameter n1 = η1 - 1; and calculate the intercept y1 of the line on the vertical axis of the coordinate system, taking the parameter B1, and taking lgB1 = y1 - lg(n1 + 1).

[0010] S-14: At any given voltage boost rate among the different voltage boost rates in S-11, perform multiple breakdown tests on the material or device under test to obtain multiple breakdown voltages;

[0011] S-15: Perform two-parameter Weibull fitting on multiple breakdown voltages to obtain the Weibull modulus m. v Take parameter m1 = m v (n1–2) / (n1+1);

[0012] S-16: Using the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV, the relationship between the breakdown probability P of the material or device under test and time t when the applied voltage is V can be calculated; where n=n1, m=m1, ln(1–P) represents the natural logarithm of 1–P, B=B1, and Γ is the gamma function;

[0013] S-17: Utilizing the applied voltage V, breakdown probability P, and time t b The relationship between the two is used to evaluate the insulation withstand voltage life of the material or device under test.

[0014] This invention employs another technical solution: a method for evaluating insulation withstand voltage life, the method comprising:

[0015] S-21: Conduct multiple voltage breakdown tests under different constant voltages and obtain the average breakdown time t under each constant voltage. b ;

[0016] S-22: Plotting the logarithm of constant voltage (lgV) on the x-axis and the logarithm of average breakdown time (lgt) on the y-axis. b Plot the vertical axis and perform linear fitting on the constant voltage data and average breakdown time data in S-21 to obtain the fitted straight line;

[0017] S-23: Calculate the slope η2 of the data fitting line, take the parameter n2 = -η2, and calculate the intercept y2 of the line on the vertical axis of the coordinate system, take the parameter B2, and take lgB2 = y2;

[0018] S-24: Under any one of the different constant voltages in S-21, perform multiple breakdown tests on the material or device under test and obtain multiple breakdown times.

[0019] S-25: Two-parameter Weibull fitting was performed on multiple breakdown times to obtain the Weibull modulus m. t Take parameter m2 = m t (n2–2);

[0020] S-26: Using the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV, the relationship between the breakdown probability P of the material or device under test and time t when the applied voltage is V can be calculated; where n=n2, m=m2, ln(1–P) represents the natural logarithm of 1–P, B=B2, and Γ is the gamma function;

[0021] S-27: Evaluation of the insulation withstand voltage life of a material or device under test by utilizing the relationship between the applied voltage V, the breakdown probability P, and the time t.

[0022] The insulation withstand voltage life evaluation method proposed in this invention can obtain the variation law of the breakdown probability of materials and devices with applied voltage and time, and evaluate the insulation withstand voltage life of materials or devices based on this law, thus achieving true insulation withstand voltage life evaluation. Attached Figure Description

[0023] Figure 1 The variation of the average breakdown voltage of the glass substrate in Example 1 with the voltage rise rate;

[0024] Figure 2 The average breakdown voltage data of the glass substrate in Example 1 is fitted using Weibull fitting.

[0025] Figure 3 The insulation withstand voltage life evaluation results of the glass substrate in Example 1;

[0026] Figure 4 The variation of the average breakdown time of the capacitor in Example 2 with the applied voltage;

[0027] Figure 5 Weibull fitting of the average breakdown time data of the capacitor device in Example 2;

[0028] Figure 6 The insulation withstand voltage life evaluation results of the capacitor components in Example 2; Detailed Implementation

[0029] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] When a voltage is applied, materials or devices that perform insulating functions may break down because they cannot withstand the voltage. Breakdown results in a through-conductive channel between the electrodes connecting the two ends of the material or device, causing the material or device to lose its insulating properties. The breakdown process is often considered to be the formation of a filamentary conductive channel. In a small region at the tip of the filamentary electrode parallel to the electric field direction, the electric field strength is proportional to the square root of the filament length, i.e., E∝E. app ·a1 / 2 Where E is the electric field strength and a is the length of the hairspring. app It is an externally applied electric field, and E app ∝V, where V is the applied voltage.

[0032] If a constant voltage is applied, the filamentary conductive channel grows slowly under this constant voltage. Assuming the growth rate of the filamentary conductive channel is proportional to a power function of the electric field strength at its tip, that is:

[0033]

[0034] Where t is time, and A and n are constants. If n≠2, after merging the variables in equation (1) and integrating, we can obtain:

[0035]

[0036] Among them, t f The breakdown time is given by a0, where a is the initial length of the filamentary conductive channel. f It is the length of the filamentary conductive channel at the point of final breakdown. Considering a f If it is much greater than a0, then equation (2) can be written as:

[0037]

[0038] Taking the logarithm of both sides of equation (3), we get:

[0039] lgt f =lgB-nlgV (4)

[0040] in, It is a constant related to the properties of the material or device. Once lgB and n are determined, the breakdown time t can be calculated using equation (4). f The relationship between the applied voltage V and the voltage V.

[0041] By analyzing static voltage breakdown test data, parameters n and lgB can be obtained. The specific process includes the following steps: conducting multiple breakdown tests under several constant voltage conditions, and obtaining the average breakdown time t under each constant voltage condition. b ; plot the logarithm of the constant applied voltage lgV on the x-axis, and the logarithm of the average breakdown time lgt on the y-axis. b Plot the data on the vertical axis and perform a linear fit between the constant applied voltage data and the average breakdown time data to obtain a fitted straight line. The negative value of the slope of the fitted straight line is the value of n, and the intercept of the straight line on the vertical axis of the coordinate system is the value of lgB.

[0042] If the applied voltage increases gradually at a specific rate of increase, i.e., V = vt, where v is the rate of voltage increase. If n ≠ 2, by merging the variables in equation (1) and integrating, we can obtain:

[0043]

[0044] Among them, V f For the breakdown voltage, considering a b If it is much greater than a0, then equation (5) can be written as:

[0045]

[0046] Taking the logarithm of both sides of equation (6), we get:

[0047] lgv=(n+1)lgV f -lgB-lg(n+1) (7)

[0048] In equation (7), by determining lgB and n, the breakdown voltage V can be calculated. f The relationship between the applied voltage V = vt and the voltage variation is analyzed using dynamic voltage breakdown test data to obtain parameters n and lgB. The specific process includes the following steps: conducting multiple breakdown tests under several different voltage rise rates to obtain the average breakdown voltage V under each voltage rise rate condition. b ; lgV, the logarithm of the average breakdown voltage b Plot the data with the logarithm of the voltage rise rate (lgv) on the x-axis and the logarithm of the voltage rise rate (lgv) on the y-axis. Perform linear fitting on the data to obtain the fitted line. The slope of the line minus 1 is the value of n. The negative value of the intercept of the line on the y-axis minus lg(n+1) is the value of lgB.

[0049] During application or testing, the breakdown voltage or breakdown time of materials or devices exhibits certain distribution characteristics, which are related to the initial length distribution characteristics of the filamentary conductive channel. Therefore, evaluating the insulation withstand voltage life requires assessing the breakdown probability under certain conditions. The breakdown voltage V obtained from dynamic loading breakdown testing... f The data follows a Weibull distribution:

[0050]

[0051] Among them, V f0 It is V f The Weibull eigenvalues ​​of the Weibull distribution, m v It is V f The Weibull modulus of the Weibull distribution. According to equation (6), V f The relationship with a0 can be obtained as follows:

[0052]

[0053] Among them, a 00 is the Weibull eigenvalue of the Weibull distribution of a0, and m is the Weibull modulus of the Weibull distribution of a0. According to the substitution process in equation (6), we can know that:

[0054]

[0055] According to equation (3), t f The relationship with a0 can be obtained as follows:

[0056]

[0057] Based on the substitution process of equation (3), we can know that:

[0058] m=(n-2)m t (12)

[0059] After transforming equation (11), we get:

[0060]

[0061] Based on the definition of B given above, that is, the relationship between B and a0, we know that the data of B should also satisfy the Weibull distribution.

[0062] According to equation (4), we can obtain:

[0063]

[0064] Where B0 is the Weibull eigenvalue of the Weibull distribution of B. In actual testing, the measured value of B should be the average value of B, which is equal to B0 × Γ(1 + (n–2) / m). The relationship between the applied voltage V, the breakdown probability P, and the time t can be obtained by solving for the average value according to the Weibull distribution:

[0065] lgt = [(n – 2) / m] × lg[–ln(1 – P)] + lgB – lg[Γ(1 + (n – 2) / m)] –nlgV (15)

[0066] In equation (15), B refers to the average value of B, and Γ is the gamma function. Equation (15) is the theoretical basis for evaluating the relationship between the breakdown probability P and time t when a voltage V is applied, i.e., the insulation withstand voltage life. The insulation withstand voltage life evaluation method includes the following steps: conducting dynamic voltage breakdown tests or static voltage breakdown tests, fitting the data to obtain the values ​​of parameters n and lgB; conducting dynamic voltage breakdown tests or static voltage breakdown tests, performing Weibull fitting analysis on the data to obtain the Weibull modulus m; based on the above values ​​of n, lgB and m, using equation (15) to calculate the relationship between the breakdown probability P and time t when a voltage V is applied.

[0067] Equation (10) is the theoretical basis for obtaining parameter m through Weibull fitting analysis of dynamic voltage breakdown test data. The specific process includes the following steps: conducting multiple breakdown tests under a specific voltage boosting rate condition to obtain multiple breakdown voltage data; performing two-parameter Weibull fitting on the breakdown voltage data to obtain the Weibull modulus equal to m. v The value of m is equal to m v Multiply by (n–2) / (n+1).

[0068] Equation (12) is the theoretical basis for obtaining parameter m through Weibull fitting analysis of static voltage breakdown test data. The specific process includes the following steps: conducting multiple breakdown tests under a constant voltage condition to obtain multiple breakdown time data; performing two-parameter Weibull fitting on the breakdown time data to obtain the Weibull modulus equal to m. t The value of m is equal to m t Multiply by (n–2).

[0069] Based on the above derivation, this application proposes a method for evaluating insulation withstand voltage lifetime. This method includes first obtaining the values ​​of parameters n and lgB through dynamic or static voltage breakdown testing; then using Weibull fitting to obtain the Weibull modulus under dynamic or static voltage breakdown testing, and calculating the relevant parameter m; finally, using the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV, calculating the relationship between the breakdown probability P and time t of the material or device under test when the applied voltage is V. This relationship can be used to evaluate the insulation withstand voltage lifetime of the material or device under test. Specifically, the insulation withstand voltage lifetime evaluation method using dynamic voltage breakdown testing includes:

[0070] S-11: Conduct multiple voltage breakdown tests at different voltage boost rates v, and obtain the average breakdown voltage V of the material or device under test at each voltage boost rate.b ;

[0071] S-12: with average breakdown voltage V b logarithm lgV b Plot a graph with the logarithm of the voltage rise rate v (lgv) as the ordinate, and perform linear fitting on the voltage rise rate and average breakdown voltage data in S-11 to obtain the fitted straight line.

[0072] S-13: Calculate the slope η1 of the data fitting line, taking the parameter n1 = η1 - 1; and calculate the intercept y1 of the line on the vertical axis of the coordinate system, taking the parameter B1, and taking lgB1 = y1 - lg(n1 + 1).

[0073] S-14: At any given voltage boost rate among the different voltage boost rates in S-11, perform multiple breakdown tests on the material or device under test to obtain multiple breakdown voltages;

[0074] S-15: Perform two-parameter Weibull fitting on multiple breakdown voltages to obtain the Weibull modulus m. v Take parameter m1 = m v (n1–2) / (n1+1);

[0075] S-16: Using the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV, the relationship between the breakdown probability P of the material or device under test and time t when the applied voltage is V can be calculated; where n=n1, m=m1, ln(1–P) represents the natural logarithm of 1–P, B=B1, and Γ is the gamma function;

[0076] S-17: Evaluation of the insulation withstand voltage life of a material or device under test by utilizing the relationship between the applied voltage V, the breakdown probability P, and the time t.

[0077] Insulation withstand voltage life evaluation methods using static voltage breakdown testing include:

[0078] S-21: Conduct multiple voltage breakdown tests under different constant voltages and obtain the average breakdown time t under each constant voltage. b ;

[0079] S-22: Plotting the logarithm of constant voltage (lgV) on the x-axis and the logarithm of average breakdown time (lgt) on the y-axis. b Plot the vertical axis and perform linear fitting on the constant voltage and average breakdown time data in S-21 to obtain the fitted straight line;

[0080] S-23: Calculate the slope η2 of the data fitting line, take the parameter n2 = -η2, and calculate the intercept y2 of the line on the vertical axis of the coordinate system, take the parameter B2, and take lgB2 = y2;

[0081] S-24: Under any one of the different constant voltages in S-21, perform multiple breakdown tests on the material or device under test and obtain multiple breakdown times.

[0082] S-25: Two-parameter Weibull fitting was performed on multiple breakdown times to obtain the Weibull modulus m. t Take parameter m2 = m t (n2–2);

[0083] S-26: Using the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV, the relationship between the breakdown probability P of the material or device under test and time t when the applied voltage is V can be calculated; where n=n2, m=m2, ln(1–P) represents the natural logarithm of 1–P, B=B2, and Γ is the gamma function;

[0084] S-27: Evaluation of the insulation withstand voltage life of a material or device under test by utilizing the relationship between the applied voltage V, the breakdown probability P, and the time t.

[0085] Example 1

[0086] This embodiment evaluates the insulation withstand voltage life of a certain type of glass substrate with a thickness of 0.5 mm and a DC high voltage. The glass substrate was cut into samples with a diameter of 30 mm. On each sample, gold-coated electrodes with a diameter of 8 mm were deposited on two circular surfaces, concentric with the circular surfaces. During the breakdown test, two hemispherical electrodes with a diameter of 5 mm were clamped between the two gold electrodes, holding the sample in place. The sample and electrodes were fully immersed in insulating oil. The insulation withstand voltage life of this glass substrate was then evaluated.

[0087] First, in this embodiment, parameters n and lgB are obtained by fitting dynamic pressure breakdown test data. The specific process is as follows:

[0088] a. Multiple breakdown tests were conducted at voltage boost rates of 50V / s, 100V / s, 200V / s, 500V / s, 1000V / s and 2000V / s respectively, with 8 test samples for each voltage boost rate, and the average breakdown voltage under each voltage boost rate condition was obtained.

[0089] b. Using the logarithm of the average breakdown voltage, lgV bPlot a graph with the average breakdown voltage data on the x-axis and the logarithm of the voltage rise rate (lgv) on the y-axis. Perform a linear fit on the average breakdown voltage data and the voltage rise rate data, such as... Figure 1 As shown, the fitted line is obtained, where the slope of the fitted line minus 1 is the value of n, and the negative value of the intercept of the fitted line on the vertical axis of the coordinate system minus lg(n+1) is the value of lgB. The values ​​of n and lgB obtained are 17.00 and 73.64, respectively.

[0090] Next, the parameter m was obtained using Weibull fitting analysis of the dynamic pressure breakdown test data. The specific process is as follows:

[0091] a. Multiple breakdown tests were conducted at a voltage rise rate of 1000V / s, with 18 samples tested, and data on the breakdown voltages of 18 samples were obtained.

[0092] b. Perform two-parameter Weibull fitting on the breakdown voltage data, such as... Figure 2 As shown, the Weibull modulus m is obtained. v The value of m is equal to 41.14. v Multiplying by (n–2) / (n+1), the value of m is 34.28.

[0093] The insulation withstand voltage life of the glass substrate was evaluated, and the specific process is as follows:

[0094] Based on the previously obtained values ​​of n, lgB, and m, the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV is used to calculate the relationship between the breakdown probability P and time t when voltage V is applied, as follows: Figure 3 As shown.

[0095] Through the Figure 3 Analysis shows that when the breakdown probability of the glass substrate after 10 years of use is less than 0.001, the applied voltage cannot exceed 5720V.

[0096] Example 2

[0097] This embodiment evaluates the insulation withstand voltage life of a capacitor with a nominal rated voltage of 180V under DC voltage conditions. The method in this embodiment includes the following steps:

[0098] First, the parameters n and lgB are obtained by fitting static pressure breakdown test data. The specific process is as follows:

[0099] a. Multiple breakdown tests were conducted under constant applied voltage conditions of 210V, 200V, 190V and 180V respectively, and the average breakdown time under each constant applied voltage condition was obtained;

[0100] b. Plot the logarithm of the constant applied voltage lgV on the x-axis, and the logarithm of the average breakdown time lgt. b Plot the data on the ordinate and perform a linear fit to obtain the fitted line, as shown below. Figure 4 As shown, the negative value of the slope of the line is the value of n, and the intercept of the line on the vertical axis of the coordinate system is the value of lgB. The calculated values ​​of n and lgB are 23.19 and 53.69, respectively.

[0101] Next, the parameter m was obtained using Weibull fitting analysis of the static pressure breakdown test data. The specific process is as follows:

[0102] a. Conduct multiple breakdown tests under a constant voltage of 210V to obtain data on multiple breakdown times;

[0103] b. Perform a two-parameter Weibull fit on the breakdown time data, such as... Figure 5 As shown, the Weibull modulus m is obtained. t It equals 1.54, and further calculations show that the value of m is equal to m. t Multiply by (n–2) to get 32.63.

[0104] Finally, the insulation withstand voltage life of the glass substrate was evaluated, and the specific process is as follows:

[0105] Based on the previously obtained values ​​of n, lgB, and m, the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV is used to calculate the relationship between the breakdown probability P and the breakdown time t when a voltage V is applied. Figure 6 As shown.

[0106] Through the Figure 6 Analysis shows that if the breakdown probability of this glass substrate is less than 0.001 after 1000 minutes of use, the applied voltage should not exceed 90V. When used at 180V, to ensure the breakdown probability remains below 0.001, the usage time should not exceed 1.3 × 10⁻⁶. -4 minute.

Claims

1. A method for evaluating insulation withstand voltage life, characterized in that, The method includes: S-11: Perform multiple voltage breakdown tests at different voltage ramping rates v, and obtain the average breakdown voltage V of the material or device under test corresponding to each voltage ramping rate b ; S-12: with average breakdown voltage V b logarithm lgV b Plotting the voltage rise rate data and the average breakdown voltage data in S-11 with the logarithm of the voltage rise rate v (lgv) as the ordinate, and performing linear fitting on the voltage rise rate data and average breakdown voltage data, we obtain the fitted straight line. S-13: Calculate the slope η1 of the fitted line, taking the parameter n1 = η1 - 1; and calculate the intercept y1 of the fitted line on the vertical axis of the coordinate system, taking the parameter B1, and taking lgB1 = y1 - lg(n1 + 1). S-14: At any given voltage boost rate among the different voltage boost rates in S-11, perform multiple breakdown tests on the material or device under test to obtain multiple breakdown voltages; S-15: Perform two-parameter Weibull fitting on multiple breakdown voltages to obtain the Weibull modulus m. v Take parameter m1 = m v (n1–2) / (n1+1); S-16: Using the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV, the relationship between the breakdown probability P of the material or device under test and time t when the applied voltage is V is calculated; where n=n1, m=m1, B=B1, ln(1–P) represents the natural logarithm of 1–P, and Γ is the gamma function; S-17: Evaluation of the insulation withstand voltage life of a material or device under test by utilizing the relationship between the applied voltage V, the breakdown probability P, and the time t.

2. A method for evaluating insulation withstand voltage life, characterized in that, The method includes: S-21: Conduct multiple voltage breakdown tests under different constant voltages and obtain the average breakdown time t under each constant voltage. b ; S-22: Plotting the logarithm of constant voltage (lgV) on the x-axis and the logarithm of average breakdown time (lgt) on the y-axis. b Plot the vertical axis and perform linear fitting on the constant voltage data and average breakdown time data in S-21 to obtain the fitted straight line; S-23: Calculate the slope η2 of the data fitting line, take the parameter n2 = -η2, and calculate the intercept y2 of the line on the vertical axis of the coordinate system, take the parameter B2, and take lgB2 = y2; S-24: Under any one of the different constant voltages in S-21, perform multiple breakdown tests on the material or device under test and obtain multiple breakdown times. S-25: Two-parameter Weibull fitting was performed on multiple breakdown times to obtain the Weibull modulus m. t Take parameter m2 = m t (n2–2); S-26: Using the equation lgt=[(n–2) / m]×lg[–ln(1–P)]+lgB–lg[Γ(1+(n–2) / m)]–nlgV, the relationship between the breakdown probability P of the material or device under test and time t when the applied voltage is V is calculated; where n=n2, m=m2, B=B2, ln(1–P) represents the natural logarithm of 1–P, and Γ is the gamma function; S-27: Evaluation of the insulation withstand voltage life of a material or device under test by utilizing the relationship between the applied voltage V, the breakdown probability P, and the time t.

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