SF6 sensor multi-stress acceleration test method

Abstract

The invention belongs to the technical field of sensor reliability evaluation, and relates to a multi-stress acceleration test method for an SF6 sensor. The method comprises the following steps: determining the type of acceleration stress and a stress application range; performing a single-factor limit test to determine the boundary of each independent stress, and obtaining a humidity stress index, a vibration stress index and an electric stress index; performing a double-factor collaborative superposition test to obtain a stress interaction correction factor of a synergistic effect; combining the four environmental stresses, and implementing an all-factor acceleration test to obtain corresponding stress parameters when the sample fails; inputting three stress indexes of humidity, vibration and electric stress, a stress interaction correction factor and a corresponding stress parameter when the sample fails into a multi-stress-level acceleration factor model, and outputting an acceleration factor; and obtaining the limit life of the sensor based on the acceleration factor. The problems that an existing SF6 sensor reliability evaluation test cannot simulate a real composite environment and has a large deviation from actual application are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sensor reliability evaluation, and particularly relates to a multi-stress accelerated test method for SF6 sensors. BACKGROUND

[0002] With the advancement of power grid digitization and the deepening of the intelligent complexity of power transmission and distribution equipment, more and more sensors are used in automatic control and detection systems of high-voltage electrical products, and the accuracy and reliability of the sensors are continuously improved. As a key detection device on power equipment such as gas insulated switchgear (GIS), the SF6 sensor can monitor the condition of SF6 gas and prevent equipment failure and safety hazards caused by gas leakage. Therefore, the service life and reliability of the SF6 sensor have an important influence on the safety and reliability of the power system.

[0003] Before being put into the market, the SF6 sensor will be subjected to factory test to ensure the quality and performance of the SF6 sensor and meet the requirements of actual application. However, the accelerated test of the SF6 sensor is mostly limited to single-stress environment (such as temperature or vibration only), but in the actual use process, the SF6 sensor needs to deal with complex environmental conditions such as high temperature, low temperature, humidity, vibration, electromagnetic interference and light aging. The gap between this single-stress test scheme in the laboratory and the complex environment in which the sensor is in long-term operation makes it difficult to truly simulate the multi-stress coupling working conditions that the SF6 sensor faces in actual work, resulting in failure phenomena such as false alarm and missed alarm of the SF6 sensor in the long-term operation process, which makes the user lack the ability to identify early defects and predict fault evolution of the power equipment, and it is difficult to truly realize observability, measurability and controllability. How to efficiently analyze and evaluate the reliability of the SF6 sensor under multi-stress environment has become a key problem to be solved in the power system.

[0004] In summary, the reliability evaluation of the SF6 sensor at present is mostly based on the accelerated life test under single stress, which cannot simulate the real complex environment and lacks effective research means for the failure mechanism under the synergistic action of multi-stress, resulting in a large deviation between the test results and actual application and difficulty in accurately predicting the long-term reliability. SUMMARY

[0005] The purpose of the application is to provide a multi-stress accelerated test method for SF6 sensors, which solves the problem that the existing reliability evaluation test of SF6 sensors cannot simulate the real complex environment and has a large deviation from the actual application.

[0006] The application is realized by the following technical scheme: The application discloses a multi-stress accelerated test method for SF6 sensors, which comprises the following processes: S1, determine the type and stress application range of the acceleration stress; the type of acceleration stress includes temperature, humidity, vibration and electric stress; S2, based on the type and stress application range of the acceleration stress, single factor limit test is carried out to determine the boundary of each independent stress, and humidity stress index, vibration stress index and electric stress index are obtained; S3, two-factor synergistic superposition test is carried out to obtain stress interaction correction factor for quantifying the synergistic effect between stresses; S4, referring to the boundary of independent stress obtained in S2, temperature, humidity, vibration and electric stress are combined to implement full-factor accelerated test, and stress parameters corresponding to sample failure are obtained; the stress parameters corresponding to sample failure include temperature value, humidity value, vibration value and voltage value; S5, input humidity stress index, vibration stress index and electric stress index obtained in S2, stress interaction correction factor obtained in S3, and stress parameters corresponding to sample failure obtained in S4 into the constructed multi-stress level acceleration factor model, and output acceleration factor; Based on the acceleration factor, the limit life of the sensor is obtained.

[0007] Further, in S2, based on the type and stress application range of the acceleration stress, single factor limit test is carried out to determine the boundary of each independent stress, specifically: Based on temperature limit test, low temperature limit T min , high temperature limit T max , and temperature failure cycle number L T are obtained; Based on humidity limit test, high humidity limit H max , low humidity limit H min , and humidity failure cycle number L H are obtained; Based on vibration limit test, vibration limit value V max , and vibration failure cycle number L V are obtained; Based on electric stress limit test, maximum failure voltage value E max , and electric stress failure cycle number L E are obtained.

[0008] Further, in S2, during the humidity limit test, the failure cycle number L Hi of the sensor at each humidity point is recorded; the humidity-life data is taken logarithm, and the power law relationship is fitted as: ; Wherein, C H is a constant, H i is the humidity value of a certain humidity point, and n is the humidity stress index; The slope -n is obtained by linear regression, and the value of the humidity stress index n is obtained.

[0009] Furthermore, in S2, during the vibration limit test, the number of failure cycles L of the sensor under each test vibration stress level is recorded. Vi Taking the logarithm of the vibration-life data, the fitted power-law relationship is as follows: ; Among them, C V V is a constant, m is the vibration stress exponent, and V i The vibration stress level at a certain vibration point; The value of the vibration stress index m is obtained by calculating the slope -m through linear regression.

[0010] Furthermore, in S2, during the electrical stress limit test, the number of failure cycles L of the sensor under each voltage is recorded. Ei Taking the logarithm of the electrical stress-life data, the fitted power-law relationship is as follows:

[0011] Among them, C E E is a constant. i Let p be the voltage value at a certain voltage point, and p be the electric stress index. The value of the electrical stress exponent p is obtained by calculating the slope -p through linear regression.

[0012] Furthermore, S3 specifically refers to: Based on a two-factor coupled experiment involving temperature and humidity, the temperature-humidity interaction term was obtained through fitting. : Based on the temperature and vibration dual-factor coupled experiment, the temperature-vibration interaction term was obtained by fitting. ; Based on a coupled humidity and vibration experiment, the humidity-vibration interaction term was obtained through fitting. ; Based on a two-factor coupled experiment involving temperature and voltage, the temperature-voltage interaction term was obtained through fitting. ; Based on a two-factor coupling experiment involving humidity and voltage, the humidity-voltage interaction term was obtained through fitting. ; Based on the voltage and vibration dual-factor coupling test, the vibration-voltage interaction term was obtained by fitting. ; The stress interaction correction factor is calculated based on the above six interaction terms. The formula for calculating the stress interaction correction factor is as follows:

[0013] F interaction This is a correction factor for stress interaction.

[0014] Further, based on the temperature and humidity double-factor coupling test, the temperature-humidity interaction term is fitted as follows , specifically: The first actual failure cycle number is obtained based on the high-temperature and high-humidity failure cycle test; The second actual failure cycle number is obtained based on the low-temperature and low-humidity failure cycle test; The third actual failure cycle number is obtained based on the low-temperature and high-humidity failure cycle test; The fourth actual failure cycle number is obtained based on the high-temperature and low-humidity failure cycle test; The minimum value of the failure cycle number obtained when temperature is taken as a single-factor limit test and the failure cycle number obtained when humidity is taken as a single-factor limit test is taken as a prediction value; The four fitting values are obtained by calculating the above four actual failure cycle numbers and the prediction value, and the temperature-humidity interaction term is obtained by averaging the four fitting values ; The four fitting values are obtained by calculating the above four actual failure cycle numbers and the prediction value, and the temperature-humidity interaction term is obtained by averaging the four fitting values

[0015] is the actual failure cycle number, is the prediction value, and i = 1, 2, 3, 4.

[0016] Further, based on the temperature and vibration double-factor coupling test, the temperature-vibration interaction term is fitted as follows , specifically: The actual failure cycle number of the SF6 sensor in the temperature and vibration coupling test environment is recorded , and the minimum value of the failure cycle number obtained when temperature is taken as a single-factor limit test and the failure cycle number obtained when vibration is taken as a single-factor limit test is taken as a prediction value ; The actual failure cycle number and the prediction value are taken as logarithms to fit , specifically as follows: .

[0017] Further, based on the humidity and vibration double-factor coupling test, the humidity-vibration interaction term is fitted as follows , specifically: The failure cycle number of the SF6 sensor in the humidity and vibration coupling test environment is recorded , the minimum value of the failure cycle number obtained when humidity is taken as a single-factor limit test and the failure cycle number obtained when vibration is taken as a single-factor limit test is taken as a prediction value ; The actual failure cycle number is compared with the prediction value , and after taking the logarithm, the following is fitted , specifically as follows: ; Based on the temperature and voltage two-factor coupling test, the temperature-voltage interaction term is fitted, specifically as follows: The failure cycle number of the SF6 sensor in the test environment of the temperature and voltage coupling test is recorded , the minimum value of the failure cycle number obtained when temperature is taken as a single-factor limit test and the failure cycle number obtained when voltage is taken as a single-factor limit test is taken as a prediction value ; The actual failure cycle number is compared with the prediction value , and after taking the logarithm, the following is fitted , specifically as follows: ; Based on the humidity and voltage two-factor coupling test, the humidity-voltage interaction term is fitted, specifically as follows: The failure cycle number of the SF6 sensor in the test environment of the humidity and voltage coupling test is recorded , the minimum value of the failure cycle number obtained when humidity is taken as a single-factor limit test and the failure cycle number obtained when voltage is taken as a single-factor limit test is taken as a prediction value ; The actual failure cycle number is compared with the prediction value , and after taking the logarithm, the following is fitted , specifically as follows: ; Based on the voltage and vibration two-factor coupling test, the vibration-voltage interaction term is fitted, specifically as follows: The failure cycle number of the SF6 sensor in the test environment of the voltage and vibration coupling test is recorded , the minimum value of the failure cycle number obtained when voltage is taken as a single-factor limit test and the failure cycle number obtained when vibration is taken as a single-factor limit test is taken as a prediction value ; The actual failure cycle number is compared with the prediction value After taking the logarithm and fitting, we obtain The details are as follows: .

[0018] Furthermore, in S5, the expression for the multi-stress-level acceleration factor model is as follows:

[0019] in, Represents the temperature term. For humidity, For vibration terms, For electrical stress, This represents the stress interaction correction factor, which is used as an interaction term. E a The activation energy is given by k, Boltzmann constant is given by T0, reference temperature is given by H0, reference humidity is given by V0, reference vibration stress level is given by E0, reference electrical stress level is given by n, humidity stress index is given by m, vibration stress index is given by p, and electrical stress index is given by p. T represents the temperature value at which the sample fails; H represents the humidity value at which the sample fails; V represents the vibration value at which the sample fails; and E represents the voltage value at which the sample fails.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects: This invention proposes a phased, progressive multi-stress accelerated testing method, which constructs a test environment with composite environmental stresses of temperature, humidity, vibration, and electrical stress. By combining three progressive test stages, it gradually reveals the failure behavior and mechanism of SF6 sensors under different stress combinations.

[0021] The first stage is a single-factor limit test. In this stage, single-type extreme environmental stresses (such as extreme high temperature, extreme low temperature, high humidity, strong vibration, overcurrent, etc.) are applied to determine the sensor's tolerance limit and initial failure characteristics under various single stresses, and to obtain the humidity stress index, vibration stress index, and electrical stress index. The main purpose of this stage is to obtain the influence law of each single-factor stress on the sensor performance, and to provide basic data for subsequent multi-factor superposition tests.

[0022] The second stage is a two-factor synergistic superposition experiment. Based on the results of the first stage, two stress factors with significant interaction effects are selected for combined loading, such as "high temperature + vibration" and "high humidity + electrical stress", to simulate the composite environment in typical application scenarios and obtain stress interaction correction factors for quantifying the synergistic effect between stresses. By analyzing the failure behavior under the synergistic effect of the two factors, the mutual influence mechanism between stresses is explored in depth, and key failure paths are identified.

[0023] The third stage is an all-factor accelerated test. On the basis of completing the first two stages, four environmental stresses of temperature, humidity, vibration and electric stress are applied to the SF6 sensor at the same time to construct a composite stress environment close to the actual working condition, and the stress parameters corresponding to the failure of the sample are obtained; the stress parameters corresponding to the failure of the sample include temperature value, humidity value, vibration value and voltage value; Finally, the humidity stress index, the vibration stress index, the electric stress index, the stress interaction correction factor of synergistic effect and the stress parameters corresponding to the failure of the sample are input into the constructed multi-stress level accelerated factor model, and the accelerated factor is output; the life of the sensor is predicted based on the accelerated factor, and the limit life is obtained.

[0024] Further, the present application proposes a multi-stress coupling accelerated factor model containing temperature, humidity, vibration and electric stress, integrates independent stress indexes (n, m, p) and stress interaction correction factors (F interaction ), and realizes quantitative evaluation of the influence of composite stress on life. The synergistic effect between stresses is scientifically quantified through interaction term fitting (such as a, b, g, etc.), which fills the theoretical gap of multi-stress coupling accelerated test. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A flowchart of a multi-stress accelerated test method for an SF6 sensor of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the following further detailed description is made in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application, that is, the described examples are only a part of the examples of the present application, but not all examples.

[0027] The components described and shown in the drawings and examples of the present application can be arranged and designed in various different configurations, therefore, the detailed description of the examples of the present application provided in the following drawings is not intended to limit the scope of the claimed present application, but only to represent a selected embodiment of the present application. Based on the drawings and examples of the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] It should be noted that the terms “comprising”, “including” or any other variant are intended to cover non-exclusive inclusion, so that a process, element, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed or inherent to the process, element, method, article or equipment.

[0029] The following is an explanation of relevant terms: Working limit: stress threshold at which the sensor function completely fails (e.g. physical damage, breakdown).

[0030] Multi-stress synergistic superposition: test mode in which two or more environmental stresses (e.g. temperature + vibration) are applied simultaneously or sequentially.

[0031] The present application provides a multi-stress accelerated test method for SF6 sensors. The core is to construct a test environment that can apply complex environmental stresses such as temperature, humidity, vibration, and voltage, and to fill the technical gap in the field of multi-stress superposition simulation tests for SF6 sensors. This method can more accurately simulate the actual use environment of the sensor, providing scientific and rigorous experimental basis for evaluating its performance and reliability, thereby significantly improving the on-site detection accuracy, operational efficiency, and overall safety of SF6 sensors.

[0032] As shown in Figure 1 , the present application provides a multi-stress accelerated test method for SF6 sensors, which adopts a phased progressive test strategy, including the following processes: S1, determining the types and stress application ranges of the accelerated stresses; S2, performing single-factor limit exploration testing based on S1 to determine the boundaries of each independent stress; S3, performing two-factor synergistic superposition testing to explore the interactive effects of key stress combinations; S4, referring to the test results of S2 and S3 as stress boundary benchmarks and working limit values, and implementing full-factor accelerated testing to simulate the most severe complex environment; S5, multi-stress accelerated test analysis and evaluation, obtaining the acceleration factor; based on the acceleration factor, the limit life of the sensor can be obtained.

[0033] The following mainly introduces S1.

[0034] The environmental stresses considered by the present application that affect the state of SF6 sensors include temperature, humidity, vibration, and electrical stress.

[0035] High temperature can cause the performance of the sensor to decline, and also cause thermal expansion and thermal drift of electronic components, affecting the stability of the measurement.

[0036] In a high-humidity environment, the sensor will be affected by moisture and corrosion; and moisture can increase electrical conductivity, causing electromagnetic interference, crosstalk, and signal loss problems; dry environments are prone to accumulate static electricity, and its discharge can cause permanent damage to the sensor.

[0037] Vibration can cause fluctuations or noise in the output signal of the sensor, affecting the stability and accuracy of the measurement.

[0038] Electric stress can cause material fatigue, insulation performance degradation, and further cause signal distortion, sensitivity reduction or sensor device failure.

[0039] According to the relevant standards and the parameters of the SF6 sensor factory test, the stress range of each test is set as follows: Temperature: range -25℃-75℃, step value 5℃, temperature change rate 20℃ / min.

[0040] Humidity: range 45%RH-95%RH, step value 5%RH, humidity change rate: 10%RH / min. RH is relative humidity.

[0041] Vibration: initial value 10g rms , step value 5g rms . g rms is the unit of vibration acceleration, indicating the root mean square value, used to quantify the vibration intensity.

[0042] Electric stress: initial value is rated voltage, step value is 5% of rated voltage.

[0043] The following mainly introduces the single factor independent fitting test of S2.

[0044] The purpose of this phase test is to determine the limits of SF6 sensor under the action of single factor of temperature, humidity, vibration and electric stress and their respective failure modes. The results will provide stress boundary and working limit reference for S4 multi-stress composite test, which is used to set the upper limit of environmental stress factor to avoid invalid test. The specific test process is as follows: 1. Temperature limit test: Low temperature step test: place the sample to be tested in the humidity chamber, the humidity is constant at 45%RH, start from 25℃, step down by 5℃, each step lasts for 20 minutes, and the last 5 minutes are for function test, until the low temperature limit T min is determined.

[0045] High temperature step test: place the sample to be tested in the humidity chamber, the humidity is constant at 45%RH, start from 25℃, step up by 5℃, each step lasts for 20 minutes, and the last 5 minutes are for function test, until the high temperature limit T max is determined.

[0046] Temperature failure cycle test: vibration and electric stress are fixed at 0. Set the humidity of the humidity chamber to be constant at 45%RH, and the temperature to cycle between T min and T max , each time at high and low temperature points for 5 minutes, the temperature change process takes 5 minutes, and the cycle number when the sample fails is recorded, which is the temperature failure cycle number L T .

[0047] 2. Humidity limit test Humidity step-up test (humidification): the sample to be tested is placed in a temperature and humidity chamber, the temperature is constant at 25℃, starting from 45%RH, the humidity is increased by 5%RH step by step, each step lasts for 20 minutes, and the last 5 minutes are for function test, until the high humidity limit H is determined max .

[0048] Humidity step-down test (dehumidification): the sample to be tested is placed in a temperature and humidity chamber, the temperature is constant at 25℃, starting from 95%RH, the humidity is decreased by 5%RH step by step, each step lasts for 20 minutes, and the last 5 minutes are for function test, until the low humidity limit H is determined min .

[0049] Humidity failure cycle test: the fixed vibration and electrical stress is 0. The temperature of the temperature and humidity chamber is constant at 25℃, and the humidity is cycled between H min and H max , each time at the high humidity and low humidity point for 5 minutes, the humidity change process takes 5 minutes, and the cycle number when the test sample fails is recorded, that is, the humidity failure cycle number L H .

[0050] Humidity stress index fitting test: other stresses are fixed as temperature 25℃, vibration and electrical stress 0. In the humidity range H min to H max , test points are set with 5%RH as the gradient interval. For each humidity point H i , if H i is positive, cycle H i to H max ; if H i is negative, cycle H i to H min , record the cycle number L Hi until the sample fails. Take H i as the horizontal coordinate and L Hi as the vertical coordinate to establish the humidity-life relationship curve, take the logarithm, and fit the power law relationship as: .

[0051] where C H is a constant, and n is the humidity stress index.

[0052] The slope-n is obtained by linear regression, and the value of the humidity stress index n is obtained.

[0053] 3. Vibration limit test The sample to be tested is installed on a vibration generator to generate three-axis six-degree-of-freedom pseudo-random vibration excitation, starting from 10g rms , increasing by 5g rmsStep up the vibration, each step lasting 20 minutes, and perform a function test for the last 5 minutes, until the vibration limit value V is determined max .

[0054] Vibration failure cycle test: the fixed temperature is 25℃, and the humidity is 45%RH. Set the vibration to cycle between 10g rms and V max , each holding for 5 minutes at the high and low points, and the vibration change process takes 5 minutes. Record the cycle number when the sample fails, which is the vibration failure cycle number L V .

[0055] Vibration stress index fitting test: other stresses are fixed at temperature 25℃, humidity 45%RH, and electric stress is 0. Within the vibration range 10g rms to V max , set the test points with a gradient interval of 5g rms . For each vibration point V i , cycle between V i and V max , and record the cycle number L Vi until the sample fails. Take V i as the horizontal coordinate and L Vi as the vertical coordinate to establish the vibration-life relationship curve, take the logarithm, and fit the power law as follows: .

[0056] where C V is a constant, and m is the vibration stress index.

[0057] Obtain the value of the vibration stress index m by linear regression of the slope-m.

[0058] 4. Electric stress limit test: Connect the sample to be tested to an adjustable power supply device, start from the rated voltage, and increase the voltage by 5% steps, each step lasting 20 minutes, until the sample fails, and record the maximum failure voltage value E max .

[0059] Electric stress failure cycle test: the fixed temperature is 25℃, and the humidity is 45%RH. Set the electric stress to cycle between the rated voltage and E max , each holding for 5 minutes at the high and low points, and the voltage change process takes 5 minutes. Record the cycle number when the sample fails, which is the electric stress failure cycle number L E .

[0060] Electric stress index fitting test: other stresses are fixed at temperature 25℃, humidity 45%RH, and vibration is 0. Between the rated voltage and E max , set the test points with a gradient interval of 5% of the rated voltage. For each voltage point Ei E i To E max The cycle is repeated, and the number of cycles L until the sample fails is recorded. Ei With E i L is the x-axis. Ei Using the vertical axis as the ordinate, establish the electrical stress-life relationship curve. Taking the logarithm of the curve, the power-law relationship is fitted as follows:

[0061] Among them, C E is a constant, and p is the electric stress exponent.

[0062] The value of the electrical stress exponent p is obtained by calculating the slope -p through linear regression.

[0063] The data obtained in this stage of the experiment are used as fitting parameters, which will be directly used in the multi-stress coupling acceleration factor model analysis method.

[0064] Experimental data analysis: The single-factor stress test results obtained from S2 can provide clear stress boundary benchmarks and working limit value references for the multi-stress composite test in S4, such as the low-temperature limit T. min Vibration limit V max These parameters will be used as the basis for setting the upper limit of each environmental stress factor in the S4 test, avoiding invalid tests due to unreasonable test interval settings. At the same time, by analyzing the performance changes of the sensor under different stress step conditions in the S2 data (such as the functional degradation trend of each gradient), the gradient setting of stress increase in the S4 test can be verified and optimized to prevent skipping potential failure critical points due to excessively large steps.

[0065] Based on the S2 data, it is helpful to identify the most significant single-factor environmental stress that affects the performance of SF6 sensors. By comparing the failure thresholds under different single stress conditions, weak points in the sensor structure or materials can be located, thus providing a basis for the focus of the S3 and S4 combined stress tests. For example, if the maximum failure voltage value of the electrical stress limit test is significantly lower than other limit values, it indicates that the SF6 sensor is electrically stress sensitive, and the S3 and S4 tests should focus on test items related to electrical stress coupling.

[0066] The following mainly introduces S3.

[0067] Based on the preliminary results of S2, this phase investigates the impact of the synergistic effect of two key environmental stresses on the reliability of SF6 sensors. The two-factor synergistic superposition test is specifically divided into the following six cases: I. Temperature and humidity coupling test: High temperature and high humidity combined step: Place the sample to be tested in a temperature and humidity chamber, starting from 25℃ and 45%RH, and increase the temperature and humidity in 5℃ and 5%RH steps for 20 minutes each, and perform sensor function testing in the last 5 minutes until the sample fails, and record the temperature value T at this time. max@HI and humidity value H max@TI .

[0068] High temperature and high humidity combined step-down: Place the sample to be tested in a temperature and humidity chamber, starting from 25℃ and 45%RH, and then decrease the temperature and humidity in 5℃ and 5%RH steps for 20 minutes each. Perform sensor function testing in the last 5 minutes until the sample fails, and record the temperature value T at this time. min@HD and humidity value H min@TD .

[0069] Low temperature and high humidity combined step: Place the sample to be tested in a temperature and humidity chamber, starting from -25℃ and 95%RH, and increase the temperature in 5℃ steps and decrease the humidity in 5%RH steps, each step lasting 20 minutes. Perform sensor function testing in the last 5 minutes until the sample fails, and record the temperature value T at this time. max@HD and humidity value H min@TI .

[0070] High temperature and low humidity combined step: Place the sample to be tested in a temperature and humidity chamber, starting from 75℃ and 45%RH, then decrease the temperature in 5℃ steps and increase the humidity in 5%RH steps, each step lasting 20 minutes. Perform sensor function testing in the last 5 minutes until the sample fails, and record the temperature value T at this point. min@HI and humidity value H max@TD .

[0071] High temperature and high humidity failure cycle test: Vibration and electrical stress are fixed at 0. The temperature and humidity chamber is set between 25℃ and T. max@H The system cycles between 45%RH and H. max@TI The sample is cycled between high and low humidity, with each cycle lasting 5 minutes. The total time for the temperature and humidity change is 5 minutes. The number of cycles until the sample fails is recorded, which is the number of high-temperature and high-humidity failure cycles, n. Tmax@HI&Hmax@TI This serves as the first actual failure cycle count.

[0072] Low temperature and low humidity failure cycle test: Vibration and electrical stress are fixed at 0. The temperature and humidity chamber is set between 25℃ and T. min@HD The system cycles between 45%RH and H. min@TD The sample is cycled between high and low humidity, maintaining each temperature and humidity level for 5 minutes. The total time for the temperature and humidity change process is 5 minutes. The number of cycles until the sample fails is recorded, which is the number of low-temperature and low-humidity failure cycles, n. Tmin@HD&Hmin@TD This serves as the second actual failure cycle count.

[0073] Low temperature high humidity failure cycle test: fixed vibration and electrical stress is 0. Set the temperature of the temperature and humidity chamber to cycle between 25°C and T max@HD , and the humidity to cycle between 45% RH and H min@TI , each for 5 minutes, with a 5 minute ramp time. Record the number of cycles at which the test specimen fails, which is the low temperature high humidity failure cycle number n Tmax@HD&Hmin@TI , as the third actual failure cycle number.

[0074] High temperature low humidity failure cycle test: fixed vibration and electrical stress is 0. Set the temperature of the temperature and humidity chamber to cycle between 25°C and T min@HI , and the humidity to cycle between 45% RH and H max@TD , each for 5 minutes, with a 5 minute ramp time. Record the number of cycles at which the test specimen fails, which is the low temperature high humidity failure cycle number n Tmin@HI&Hmax@TD , as the fourth actual failure cycle number.

[0075] II. Temperature + vibration coupling test (mechanical thermal fatigue) Fast temperature cycling with vibration step-up: Set the temperature and humidity chamber to cycle between -25°C and 75°C at a rate of 20°C / min, with each high and low temperature point held for 5 minutes. Start the vibration level at 10g rms and increase by 5g rms per step, with each step lasting 20 minutes, and perform sensor function tests during the last 5 minutes, until the test specimen fails. Record the cycle number n T@VI and the vibration value V max@T at that time. The humidity is constant at 45% RH.

[0076] Fast temperature cycling with vibration cycling: cycle the temperature between -25°C and 75°C, and cycle the vibration stress from 10g rms to the failure limit value, as follows: a) Phase A (low temperature + low vibration): temperature is -25°C and the vibration acceleration is 10g rms for 10 minutes; b) Phase B (low temperature + vibration limit): hold the temperature at -25°C and increase the vibration acceleration to the vibration limit value V max for 10 minutes; c) Phase C (high temperature + vibration limit): increase the temperature to 75°C and hold the vibration at the vibration limit value V max for 10 minutes; d) Phase D (high temperature + low vibration): hold the temperature at 75°C and decrease the vibration acceleration to 10g rms for 10 minutes; e) Phase E (recovery and test): decrease the temperature to 25°C and decrease the vibration acceleration to 0grms , keep 10 minutes, and perform sensor function test in the last 5 minutes.

[0077] f) Repeat a) to e) to constitute a complete cycle until the test piece fails, and record the cycle number n T&V , humidity is kept constant at 45% RH.

[0078] Three, humidity + vibration coupling test Fast humidity change cycle superimposed vibration step: set the temperature and humidity chamber to cycle between 45% RH and 95% RH at a rate of 10% RH / min, each at the high and low temperature points for 5 minutes; vibration level starts to increase from 10g rms , with a step value of 5g rms , each step lasts for 20 minutes, and sensor function test is performed in the last 5 minutes until the test piece fails; record the cycle number n H@VI and the vibration value V at this time max@H , temperature is kept constant at 25°C.

[0079] Fast humidity change cycle superimposed vibration cycle: humidity cycles between 45% RH and 95% RH, vibration stress cycles from 10g rms to the failure limit value, as follows: a) Stage A (low humidity + low vibration): humidity 45% RH, vibration 10g rms , keep 10 minutes; b) Stage B (low humidity + vibration limit): keep 45% RH, vibration increased to vibration limit value V max , keep 10 minutes; c) Stage C (high humidity + vibration limit): humidity increased to 95% RH, keep vibration at vibration limit value V max , keep 10 minutes; d) Stage D (high humidity + low vibration): keep 95% RH, vibration decreased to 10g rms , keep 10 minutes; e) Stage E (recovery and test): humidity decreased to 60% RH, vibration decreased to 0g rms , keep 10 minutes, and perform sensor function test in the last 5 minutes.

[0080] f) Repeat a) to e) to constitute a complete cycle until the test piece fails, and record the cycle number n H&V , temperature is kept constant at 25°C.

[0081] Four, voltage + temperature coupling test Overvoltage condition superimposed temperature cycling: humidity constant at 45% RH, constant limit voltage of 120% rated voltage applied to the sample; set the temperature and humidity chamber to cycle between -25°C and 75°C at a rate of 20°C / min, each hold at the high and low temperature points for 5 minutes; record the number of cycles n to failure of the test article T@E .

[0082] V. Voltage + humidity coupling test Overvoltage condition superimposed humidity cycling: temperature constant at 25°C, constant limit voltage of 120% rated voltage applied to the sample; set the temperature and humidity chamber to cycle between 45% RH and 95% RH at a rate of 10% RH / min, each hold at the high and low humidity points for 5 minutes; record the number of cycles n to failure of the test article H@E .

[0083] VI. Voltage + vibration coupling test Overvoltage condition superimposed vibration stepping: temperature constant at 25°C, humidity constant at 45% RH. Constant limit voltage of 120% rated voltage applied to the sample; vibration level starts at 10g and increases by steps of 5g rms rms , each step lasting 20 minutes, and sensor function test is performed in the last 5 minutes, until the test article fails, record the vibration value V at this time max@E .

[0084] Vibration overvoltage failure cycle test: fixed temperature 25°C, humidity 45% RH, electrical stress is 120% rated voltage. Set the vibration to cycle between 10g rms and V max , each hold at the high and low for 5 minutes, the vibration change process takes 5 minutes, record the number of cycles when the test article fails, that is, the vibration overvoltage failure cycle number n V@E .

[0085] The data obtained from this stage of two-factor synergistic superimposed test is the interaction correction factor, which will be directly used in the multi-stress coupling acceleration factor model analysis method. The stress interaction correction factor F interaction is used to quantify the synergistic effect between stresses, the fitting formula is as follows:

[0086] coefficient obtained by fitting the temperature and humidity two-factor test, obtained by fitting the temperature + vibration, obtained by fitting the humidity + vibration, obtained by fitting the temperature + voltage, obtained by fitting the humidity + voltage, obtained by fitting the vibration + voltage. ​

[0087] Temperature-humidity interaction term : Record the actual failure cycle number of SF6 sensor in each group of temperature and humidity test environment , high temperature and high humidity (T max@HI , H max@TI ) L α实际1 =n Tmax@HI&Hmax@TI , low temperature and low humidity (T min@HD , H min@TD ) L α实际2 =n Tmin@HD&Hmin@TD , low temperature and high humidity (T max@HD , H min@TI ) L α实际3 =n Tmax@HD&Hmin@TI , high temperature and low humidity (T min@HI , H max@TD ) L α实际4 =n Tmin@HI&Hmax@TD .

[0088] And compare the predicted value obtained by single factor test Take the logarithm and fit , as follows:

[0089] The values of the four test combinations of , , , are calculated, and the average value of the interaction term is obtained.

[0090] Temperature-vibration interaction term : Record the actual failure cycle number of SF6 sensor in temperature + vibration coupling test environment , , the single factor model prediction value is . Take the logarithm and fit , as follows:

[0091] Humidity-vibration interaction term : Record the failure cycle number of SF6 sensor in humidity + vibration coupling test environment , , the single factor model prediction value is . Take the logarithm and fit , as follows:

[0092] Temperature-voltage interaction term : At this time, the failure cycle number is , the single-factor model prediction value is After taking the logarithm, the fitting is as follows:

[0093] Humidity-voltage interaction term : the failure cycle number of SF6 sensor at this time , the single-factor model prediction value is After taking the logarithm, the fitting is as follows:

[0094] Vibration-voltage interaction term : the failure cycle number of SF6 sensor at this time , the single-factor model prediction value is After taking the logarithm, the fitting is as follows:

[0095] The following mainly introduces the full-factor accelerated test of S4. In this phase, temperature, humidity, vibration and electrical stress are combined to simulate the most severe combined working conditions, and the sensor acceleration test is implemented. During the experiment, the synchronous superimposed multi-stress step test or the sequential superimposed multi-stress test can be selected.

[0096] Synchronous superimposed multi-stress step test: that is, when the four kinds of acceleration stresses are applied at the same time, it is possible to change the failure mechanism and excite new failure modes. The purpose of this test is to simulate the extreme working condition that the stresses are simultaneously increased to the limit. The initial values are temperature-25℃, humidity 45%RH, vibration 10g rms , 20% of the rated voltage. Each step increases the stress (temperature +5℃, humidity +5%RH, vibration +5g rms , voltage +5%), each stress level is maintained for 20 minutes, and the function is tested for the last 5 minutes. Repeat until the sample fails to determine the stress parameters corresponding to the sample failure, including temperature value, humidity value, vibration value and voltage value.

[0097] Sequential superimposed multi-stress test: that is, temperature, humidity, vibration and voltage are gradually superimposed in a fixed order and time interval until the limit of each stress is reached, and the performance damage and critical point under the cumulative effect are observed to determine the stress parameters corresponding to the sample failure. The order of the four stresses can be combined at will. The purpose of this test is to observe the cumulative damage of performance when the stresses are applied in a specific order.

[0098] The all-factor accelerated test constructs a comprehensive stress field closer to the real use environment. The stress parameters corresponding to the failure of the sample obtained by S4 are input into the multi-stress level acceleration factor model of S5, and the ultimate life of the sensor can be obtained based on the acceleration factor. The test results show that the influence of multi-stress interaction is much smaller than that of double-factor interaction, and the interaction effect of the latter is more critical and has a stronger dominant effect on the failure mechanism of the product. Therefore, the correction factor of the multi-stress high-order interaction term can be reasonably ignored in engineering modeling to simplify the analysis model. The core value of the all-factor accelerated test focuses on identifying the key stress or sensitive factor that still continues to play a dominant role in the multi-stress environment and clearly identifying the key stress combination that truly affects the life of the product, thereby providing priority basis for design optimization.

[0099] Locking the key stress aspects in the actual working condition, through dynamic monitoring of the sensor performance parameters during the all-factor test process, the key stress or sensitive factor that still continues to drive performance degradation in the comprehensive environment can be identified. For example, a certain sensor shows significant temperature-vibration coupling effect in the double-factor test, but in the all-factor test, it is found that high humidity environment is the root cause of insulation failure.

[0100] In terms of resource design, the all-factor test clearly identifies which stresses and their interactions truly affect the life of the product through empirical methods, thereby providing priority basis for design optimization. Designers can accordingly concentrate key resources on the core stress links verified as sensitive, and appropriately relax the design margin for non-sensitive factors with weak impact, achieving the best balance between reliability and economy.

[0101] The samples used in the above test process are SF6 sensors produced by the same manufacturer and from the same batch. The test sample size is generally selected to be at least 5 at each stress level. The SF6 sensor is placed in the test environment and continuously tested without interruption according to the corresponding accelerated stress level. The health status parameters of the sample are monitored in real time and recorded during the test until the end of the test. The following mainly introduces the multi-stress accelerated test analysis and evaluation of S5.

[0102] The multi-stress coupling acceleration factor model quantifies the acceleration effect of the composite environment on the life of the SF6 sensor by integrating the independent effects of each stress and their interaction effects, and establishes a multi-stress level acceleration factor model:

[0103] wherein, represents the temperature term, is the humidity term, is the vibration term, is the electrical stress term, The stress interaction correction factor is represented as an interaction term, and the specific letter meaning and physical meaning are shown in the following table:

[0104] Wherein, the values of n, m and p are calculated in the single-factor independent fitting test, F interaction The value of T is the temperature value corresponding to the failure of the sample, H is the humidity value corresponding to the failure of the sample, V is the vibration value corresponding to the failure of the sample, and E is the voltage value corresponding to the failure of the sample.

[0105] Based on the test data of S2 and S3, a multi-stress level acceleration factor model is constructed, and according to the experimental results of S4, the most critical sensitive factor and main failure combination under the action of multiple stresses are determined, and the priority order for design improvement is determined.

[0106] According to the test data, engineering improvement guidance can be carried out. For example, the S4 data shows that the failure rate of the “voltage + humidity” combination is too high, so the moisture-proof packaging process of the sensor needs to be improved; if the vibration stress causes a high reduction rate of the working limit in the multi-factor test, it indicates that the mechanical structure needs to be strengthened to resist fatigue design. Therefore, the joint analysis of the test data not only verifies the effectiveness of the acceleration test method, but also forms a closed-loop reliability evaluation system from the failure threshold, coupling mechanism to design optimization, which provides a scientific basis for the design, production and operation of SF6 sensors.

[0107] The present application proposes a multi-stress acceleration test process in stages, that is, starting from single-factor limit test, gradually transitioning to double-factor synergistic superposition test, and finally entering full-factor comprehensive acceleration test, forming a failure exposure path from simple to complex, layer by layer, so as to effectively identify the performance degradation law and key failure mode under the action of different stresses, and systematically reveal the failure mechanism of SF6 sensor under the action of multiple stress coupling. Through the gradual approximation of real working conditions by stage tests, the problem that the traditional single-factor or simple multi-factor test cannot simulate the complex stress interaction is solved; The present application proposes a multi-stress coupling acceleration factor model containing temperature, humidity, vibration and electric stress, which integrates independent stress indexes (n, m, p) and interaction correction factors (F interaction ), and realizes the quantitative evaluation of the influence of composite stress on life. Through the fitting of interaction terms (such as α, β, γ, etc.), the synergistic effect between stresses is scientifically quantified, filling the theoretical gap of multi-stress coupling acceleration test.

[0108] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement should be covered in the protection scope of the claims of the present application.

Claims

1. A multi-stress accelerated testing method for SF6 sensors, characterized in that, The process includes the following: S1. Determine the type of accelerating stress and the range of stress application; Accelerating stresses include those caused by temperature, humidity, vibration, and electrical stress. S2. Based on the type of accelerating stress and the stress application range, single-factor limit tests are conducted to determine the boundaries of each independent stress and obtain the humidity stress index, vibration stress index and electrical stress index. S3. Conduct a two-factor synergistic superposition test to obtain a stress interaction correction factor for quantifying the synergistic effect between stresses; S4. Referring to the boundary of the independent stress obtained in S2, the four environmental stresses of temperature, humidity, vibration and electrical stress are combined and a full-factor accelerated test is carried out to obtain the stress parameters corresponding to the sample failure. The stress parameters corresponding to the sample failure include temperature value, humidity value, vibration value and voltage value. S5. Input the humidity stress index, vibration stress index, and electrical stress index obtained in S2, the stress interaction correction factor obtained in S3, and the stress parameters corresponding to sample failure obtained in S4 into the constructed multi-stress level acceleration factor model, and output the acceleration factor. The sensor's ultimate lifetime is determined based on the acceleration factor.

2. The multi-stress accelerated testing method for an SF6 sensor according to claim 1, characterized in that, In S2, single-factor limit tests are performed based on the type and range of accelerated stress to determine the boundaries of each independent stress, specifically: The low-temperature limit T was obtained based on temperature limit test experiments. min High temperature limit T max Temperature failure cycle count L T ; The high humidity limit H was obtained based on humidity limit test experiments. max Low humidity limit H min Humidity failure cycle count L H ; The vibration limit value V is obtained based on the vibration limit test. max Vibration failure cycle count L V ; The maximum failure voltage value E was obtained based on the electrical stress limit test. max Number of electrical stress failure cycles L E .

3. The multi-stress accelerated testing method for an SF6 sensor according to claim 1, characterized in that, In S2, during the humidity limit test, the number of sensor failure cycles L at each humidity point is recorded. Hi Taking the logarithm of the humidity-lifetime data, the fitted power-law relationship is as follows: ; Among them, C H H is a constant. i Let be the humidity value at a certain humidity point, and n be the humidity stress index; The slope -n is obtained by linear regression, and the value of the humidity stress index n is obtained.

4. The multi-stress accelerated testing method for an SF6 sensor according to claim 1, characterized in that, In S2, during the vibration limit test, the number of failure cycles L of the sensor under each test vibration stress level is recorded. Vi Taking the logarithm of the vibration-life data, the fitted power-law relationship is as follows: ; Among them, C V V is a constant, m is the vibration stress exponent, and V i The vibration stress level at a certain vibration point; The value of the vibration stress index m is obtained by calculating the slope -m through linear regression.

5. The multi-stress accelerated testing method for an SF6 sensor according to claim 1, characterized in that, In S2, during the electrical stress limit test, the number of failure cycles L of the sensor under each voltage is recorded. Ei Taking the logarithm of the electrical stress-life data, the fitted power-law relationship is as follows: Among them, C E E is a constant. i Let p be the voltage value at a certain voltage point, and p be the electric stress index. The value of the electrical stress exponent p is obtained by calculating the slope -p through linear regression.

6. The multi-stress accelerated testing method for an SF6 sensor according to claim 1, characterized in that, S3 specifically refers to: Based on a two-factor coupled experiment involving temperature and humidity, the temperature-humidity interaction term was obtained through fitting. : Based on the temperature and vibration dual-factor coupled experiment, the temperature-vibration interaction term was obtained by fitting. ; Based on a coupled humidity and vibration experiment, the humidity-vibration interaction term was obtained through fitting. ; Based on a two-factor coupled experiment involving temperature and voltage, the temperature-voltage interaction term was obtained through fitting. ; Based on a two-factor coupling experiment involving humidity and voltage, the humidity-voltage interaction term was obtained through fitting. ; Based on the voltage and vibration dual-factor coupling test, the vibration-voltage interaction term was obtained by fitting. ; The stress interaction correction factor is calculated based on the above six interaction terms. The formula for calculating the stress interaction correction factor is as follows: F interaction This is a correction factor for stress interaction.

7. The multi-stress accelerated testing method for an SF6 sensor according to claim 6, characterized in that, Based on a temperature and humidity dual-factor coupling experiment, the temperature-humidity interaction term was obtained through fitting. Specifically: The first actual number of failure cycles was obtained based on the high temperature and high humidity failure cycle test; The second actual number of failure cycles was obtained based on the low temperature and low humidity failure cycle test; The third actual failure cycle number was obtained based on the low temperature and high humidity failure cycle test; The fourth actual failure cycle number was obtained based on the high temperature and low humidity failure cycle test; The minimum of the failure cycle counts obtained from temperature and humidity in the single-factor limit test is used as the predicted value. The four actual failure cycles were compared with the predicted values ​​to obtain four fitted values. The average of the four fitted values ​​was then used to obtain the temperature-humidity interaction term. ; The four actual failure cycles were compared with the predicted values ​​to obtain four fitted values. The specific calculation formulas used are as follows: This represents the actual number of failure cycles. For the predicted values, i = 1, 2, 3, 4.

8. The multi-stress accelerated testing method for an SF6 sensor according to claim 6, characterized in that, Based on the temperature and vibration dual-factor coupled experiment, the temperature-vibration interaction term was obtained by fitting. Specifically: Record the actual number of failure cycles of the SF6 sensor under the test environment of temperature and vibration coupling test. The minimum of the failure cycle counts obtained from single-factor limit testing (temperature and vibration) is used as the predicted value. ; The actual number of failure cycles Compared with the predicted value After taking the logarithm and fitting, we obtain The details are as follows: 。 9. The multi-stress accelerated testing method for an SF6 sensor according to claim 6, characterized in that, Based on a coupled humidity and vibration experiment, the humidity-vibration interaction term was obtained through fitting. Specifically: Record the number of failure cycles of the SF6 sensor under the test environment of humidity and vibration coupling test. The minimum of the failure cycle counts obtained from humidity and vibration in the single-factor limit test is used as the predicted value. ; The actual number of failure cycles Compared with the predicted value After taking the logarithm and fitting, we obtain The details are as follows: ； Based on a two-factor coupled experiment involving temperature and voltage, the temperature-voltage interaction term was obtained through fitting. Specifically: Record the number of failure cycles of the SF6 sensor under the test environment of temperature and voltage coupling test. The minimum of the failure cycle counts obtained from the single-factor limit test (temperature and voltage) is taken as the predicted value. ; The actual number of failure cycles Compared with the predicted value After taking the logarithm and fitting, we obtain The details are as follows: ； Based on a two-factor coupling experiment involving humidity and voltage, the humidity-voltage interaction term was obtained through fitting. Specifically: Record the number of failure cycles of the SF6 sensor under the test environment of humidity and voltage coupling test. The minimum of the failure cycle counts obtained from humidity and voltage during the single-factor limit test was used as the predicted value. ; The actual number of failure cycles Compared with the predicted value After taking the logarithm and fitting, we obtain The details are as follows: ； Based on the voltage and vibration dual-factor coupling test, the vibration-voltage interaction term was obtained by fitting. Specifically: Record the number of failure cycles of the SF6 sensor under the test environment of voltage and vibration coupling test. The minimum of the failure cycle counts obtained from single-factor limit testing (voltage) and vibration is taken as the predicted value. ; The actual number of failure cycles Compared with the predicted value After taking the logarithm and fitting, we obtain The details are as follows: 。 10. The multi-stress accelerated testing method for an SF6 sensor according to claim 1, characterized in that, In S5, the expression for the multi-stress-level acceleration factor model is as follows: in, Represents the temperature term. For humidity, For vibration terms, For electrical stress, This represents the stress interaction correction factor, which is used as an interaction term. E a The activation energy is given by k, Boltzmann constant is given by T0, reference temperature is given by H0, reference humidity is given by V0, reference vibration stress level is given by E0, reference electrical stress level is given by n, humidity stress index is given by m, vibration stress index is given by p, and electrical stress index is given by p. T represents the temperature value at which the sample fails; H represents the humidity value at which the sample fails; V represents the vibration value at which the sample fails; and E represents the voltage value at which the sample fails.

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