CN114624526A - Stepping stress accelerated life test method for evaluating reliability of electric meter - Google Patents
Stepping stress accelerated life test method for evaluating reliability of electric meter Download PDFInfo
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- CN114624526A CN114624526A CN202111565018.2A CN202111565018A CN114624526A CN 114624526 A CN114624526 A CN 114624526A CN 202111565018 A CN202111565018 A CN 202111565018A CN 114624526 A CN114624526 A CN 114624526A
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention discloses a stepping stress accelerated life test method for evaluating reliability of an ammeter, which comprises the following steps: determining the life characteristics of the batch of electric meters; determining a temperature and humidity stress level according to the temperature and humidity of the installation environment of the batch of electric meters; calculating to obtain an acceleration factor value according to the service life characteristics and the temperature, humidity and stress levels; calculating the test days corresponding to the stress level according to the acceleration factor value; placing an electric meter sample into a temperature and humidity box for testing; observing the failure condition of the electric meter sample, if no failure occurs, continuing the test until the test is finished, and judging that the service life characteristics are met by the batch electric meters; and if the service life of the batch of electric meters is invalid, judging that the service life characteristics are not met by the batch of electric meters. The invention provides a stepping stress accelerated life test method for testing the life of an ammeter, which reduces data arrangement and operation work and labor cost on one hand; on the other hand, the number of the test equipment and the number of the to-be-tested electric meters are reduced, and the test cost is saved; moreover, the testing time is greatly shortened, and the development efficiency is improved.
Description
Technical Field
The invention relates to the field of ammeter service life testing, in particular to a stepping stress accelerated service life testing method for evaluating reliability of an ammeter.
Background
The service life of the electric meter is an important index for evaluating the reliability of the electric meter, and particularly, the service life characteristics of the electric meter are predicted by an effective method. If the life characteristic parameters are obtained through the actual use condition of the electric meter, the life characteristic parameters are hardly feasible, so that the electric meter is required to be subjected to an accelerated life test for estimating the life in a short time.
Accelerated life tests accelerate the excitation failure by applying higher stress than normal use conditions, shortening the working time before failure. Temperature and humidity are two major stresses affecting the service life of the electric meter, and currently, in the field of service life test of the electric meter, the most widely applied stress is under five groups of constant temperature and humidity stress levels (T)max&RHmax、Tmax&RHmed、Tmax&RHmin、Tmed&RHmax、Tmin&RHmax) On one hand, the test needs a large amount of data arrangement and operation, and consumes more labor cost; on the other hand, at least 5 test devices and 150 tested sample machines are needed, so that the test cost is high; moreover, the testing time is long, which affects the development efficiency.
Disclosure of Invention
The invention provides a stepping stress accelerated life test method for evaluating reliability of an ammeter, aiming at overcoming the problems of higher test cost, longer test time and influence on development efficiency in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a stepping stress accelerated life test method for evaluating reliability of an ammeter comprises the following steps: s1: selecting a certain number of electric meter samples to be tested from the batch of electric meters, and determining the service life characteristics of the batch of electric meters; s2: temperature T according to installation environment of batch of electricity metersuAnd humidity RHuDetermining the stress level of the temperature and the humidity; s3: calculating to obtain an acceleration factor AF according to the service life characteristics and the temperature and humidity stress level of the batch of electric metersmaxA value; s4: according to an acceleration factor AFmaxCalculating values to obtain the corresponding stress test days D of each stress group in the temperature and humidity stress level; s5: putting a certain number of electric meter samples to be tested into a temperature and humidity box for testing; s6: observing the failure condition of the tested ammeter sample within a fixed time interval, if no failure occurs, continuing the test until the test is finished, indicating that the test result of the ammeter sample is qualified, and judging that the batch of ammeters meet the service life characteristics; if the test result is invalid, the test result of the electric meter sample is unqualified, and the batch electric meters are judged not to meet the service life characteristic. The invention provides a stepping stress accelerated life test method for evaluating the reliability of an ammeter, which specifies test conditions according to life characteristics, does not allow the occurrence of failure rate in test time, reduces data arrangement and operation work and reduces labor cost on one hand; on the other hand, the number of test equipment and electric meter samples to be tested, namely prototype machines, is reduced, and the test cost is saved; moreover, the test time is greatly shortened, and the development efficiency is improved; in general, the method is more practical, and is convenient for manufacturers to evaluate the reliability of the product.
As a preferable scheme of the present invention, the lifetime characteristics of the electric meter to be tested in S1 are specifically: after the electric meter works for Y years, the failure rate is lower than F%, and the confidence coefficient is CL. After the test is finished, if the ammeter samples have no failure condition, the failure rate is lower than F% after the batch of ammeters meet Y years, and the confidence coefficient is the service life characteristic of CL; if the failure condition occurs in the test process, the failure rate is lower than F% after the batch of electric meters do not meet Y years, and the confidence coefficient is the service life characteristic of CL.
As a preferable scheme of the invention, the temperature and humidity stress level in S2 comprises a plurality of temperature constant stresses&Humidity step stress set, several temperature step stresses&A humidity constant stress set; constant stress at the temperature&Humidity step stress set, i.e. temperature TmHumidity RH as constant stressmAs step stress, constant stress at a temperature&Temperature T in humidity step stress setmIs a constant value, Tmin≤Tm≤TmaxHumidity RHmFor a number of stepwise increasing step values, i.e. RHmin≤RHm1＜RHm2＜……＜RHmn≤RHmaxN is the number of steps, i.e. the number of step stresses; constant stress of the humidity&Temperature step stress set, i.e. humidity RHmAs constant stress, temperature TmAs step stress, constant stress at a humidity&Humidity RH in temperature step stress setmAt a constant value, RHmin≤RHm≤RHmaxTemperature TmFor a number of step-by-step increasing values, i.e. Tmin≤Tm1＜Tm2……＜Tmn≤TmaxAnd n is the number of steps. E.g. constant stress at a temperature&In the humidity step stress group, n is 3, and T is takenm＝Tmin，RHm1＝RHmin，RHm2＝RHmed，RHm3＝RHmaxThe temperature is constant&The humidity step stress set is: t ismin&RHmin、Tmin&RHmed、Tmin&RHmaxThree stress levels; constant stress at a humidity&In the temperature step stress set, n is 2, and RH is takenm＝RHmax，Tm1＝Tmin，Tm2＝TmaxThe humidity is constant stress&The set of temperature step stresses comprises: RH (relative humidity)max&Tmin、RHmax&TmaxTwo stress levels.
As a preferable embodiment of the present invention, the acceleration factor AF in S3 ismaxThe calculation formula is as follows:
wherein RH isuAnd RHSRelative humidity, T, under normal use conditions and stress conditions, respectivelyuAnd TSThe temperature under normal use condition and stress condition, respectively, is expressed as thermodynamic temperature, k is Boltzmann constant, EaAnd N is a modulusTwo coefficients of type, EaThe activation energy in electron volts was taken to be 0.9, and N was taken to be a constant, and 3 was taken. The service life, the temperature and the humidity of the electric meter meet the Peck temperature-humidity model, and the invention adopts common value estimation; the temperature and humidity model is not limited to the above model, other temperature and humidity models can be selected, and an acceleration factor AF is calculated for each stress levelmax。
As a preferred embodiment of the present invention, the calculation formula of the corresponding stress test days D of each stress group in the temperature and humidity stress level in S4 is as follows:
D＝Dmin/n
wherein Y is life time, F is failure rate, UCL1The confidence level CL is the unreliable estimation of the sequence number 1, C is a contribution value, the value is generally less than 15%, beta is a shape parameter, the value is obtained before 0.5-5%, and AFmaxIs the acceleration factor and n is the number of steps. In the traditional test method, when the number of samples of a certain fault phenomenon does not reach 5 required samples, the test reaches 2 times of DminStopping after time, which is longer relative to the test days of the present invention.
As a preferred embodiment of the present invention, the S5 specifically is: putting a certain amount of ammeter samples to be tested into a temperature and humidity box, selecting a stress set for testing, wherein the stepping stress is gradually increased along with the time in the testing process, and all the tested samples are loaded with a voltage UnLoaded with a current of 0.1ImaxThe power factor is 0.5-1. The power factor value is related to the test equipment and the power supply, and is usually 0.5, 0.8 or 1.
As a preferred embodiment of the present invention, the S6 specifically is: observing the failure condition of the tested ammeter sample within a fixed time interval, if no failure occurs, continuing the test until the test is finished, indicating that the test result of the ammeter sample is qualified, and judging that the failure rate is lower than F% after Y years is met by batch ammeters, wherein the confidence coefficient is the life characteristic of CL; if the test result of the ammeter sample is unqualified, the batch ammeter judges that the fault rate is lower than F% after Y years are not met, and the confidence coefficient is the life characteristic of CL. Displaying, communicating, storing and reading data, and judging the test failure of the electric meter sample when any one of the abnormal conditions occurs.
Therefore, the invention has the following beneficial effects: the invention provides a stepping stress accelerated life test method for evaluating the reliability of an ammeter, which reduces data arrangement and operation work and labor cost on one hand; on the other hand, the number of test equipment and the number of electric meters to be tested, namely prototype machines, are reduced, and the test cost is saved; moreover, the testing time is greatly shortened, and the development efficiency is improved; in general, the method is more practical and is convenient for manufacturers to evaluate the reliability of the products.
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FIG. 1 is a flow chart of a method of the present invention;
fig. 2 is a annual temperature and humidity map of a certain city in accordance with an embodiment of the present invention.
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings.
As shown in FIG. 1, a stepping stress accelerated life test method for evaluating reliability of an ammeter comprises the steps of firstly, drawing up life characteristic requirements such as product life age, failure rate and confidence level, and carrying out stepping stress accelerated life test under test conditions required by the requirements, wherein the successful test indicates that the product life meets the initially drawn up requirements. The test conditions comprise stress level, loading voltage, current, minimum test days and the like; the criterion for test success was that no failed samples were produced in all tests.
S1: determining the service life characteristics, wherein the failure rate is lower than F% after Y years, and the confidence coefficient is CL;
s2: temperature T according to installation environmentuAnd humidity RHuDetermining the temperature and humidity stress level, including a plurality of temperature constant stresses&Set of humidity step stresses and plurality of temperature step stresses&A humidity constant stress set;
s3: respectively substituting the corresponding stress in each group of corresponding groups into the following formula to obtain the acceleration factor A of each corresponding stressFmaxThe value:
in the formula, RHuAnd RHSRelative humidity under normal use conditions and stress conditions, respectively; t isuAnd TSTemperatures in normal use and stress conditions, respectively, expressed in K; k is Boltzmann's constant, 8.617x10-5eV/K；EaAnd n are two coefficients of the model, EaThe typical value of the activation energy expressed by electron voltage is 0.9, and the typical value of n as a constant is 3;
s4: AF to be obtainedmaxThe number of test days D for the corresponding stress level can be calculated by substituting the values into the following equation:
D＝Dmin/n
y, F for age and failure rate; UCL1The reliability of sequence number 1 is estimated for confidence CL; c is a contribution value, and the value is generally less than 15%; beta is taken before 0.5-5, beta is a shape parameter, AFmaxIs the acceleration factor and n is the number of steps. In the traditional test method, when the number of samples of a certain fault phenomenon does not reach 5 required, the test reaches 2 times of DminStopping after time, takes longer relative to the test days of the present invention.
S5: putting a certain amount of ammeter samples to be tested into a temperature and humidity box, selecting a stress set for testing, wherein the stepping stress is gradually increased along with the time in the testing process, and all the tested samples are loaded with a voltage UnLoaded with a current of 0.1ImaxThe power factor is 0.5-1, and the value of the power factor is related to test equipment and a power supply, and is usually 0.5, 0.8 or 1;
s6: observing the failure condition of the tested sample in a fixed time interval, if no failure occurs, continuing the test until the test is finished, and judging that the failure rate is lower than F% after Y years is met and the confidence coefficient is the life characteristic of CL by the batch of electric meters; if the fault exists, the test fails, and the batch ammeter judges that the fault rate is lower than F% after the fault rate does not meet Y years and the confidence coefficient is the life characteristic of CL. And displaying, communicating, storing and reading data, and judging the test failure when any one of the abnormalities appears.
Example (b): for a batch of rated voltages Un230V, maximum current ImaxThe electric meter which is 100A is installed in a certain city, whether the service life of the electric meter can meet the requirement of 10 years needs to be evaluated, the failure rate is lower than 5 percent, and the confidence coefficient is 50 percent; the annual humiture conditions of a certain city are obtained by searching, and T is obtained as shown in figure 2 (the humiture of the region where the ammeter is actually installed and used is selected, and the annual humiture of the region can be inquired through a website), and the annual humiture of the region is obtainedu＝20℃，RHu75%, the present example determines a set of temperature-constant stresses&Humidity step stress set and temperature step stress set&Constant humidity stress set and constant temperature stress&The step number n of the humidity step stress set is 2, and is as follows: t ismax&RHmin、Tmax&RHmedTemperature step stress&The stepping number n of the humidity constant stress set is 3, and the stepping number n is as follows: t is a unit ofmin&RHmax、Tmed&RHmax、Tmax&RHmaxCan determine Tmin＝70℃；Tmed＝75℃；Tmax＝80℃；RHmin＝85％；RHmed＝90％；RHmax95%, substituting the above parameters into the acceleration factor AFmaxObtaining acceleration factors AF under each group of stress levels by a calculation formulamaxAs shown in the second column of table 1; AF to be obtainedmaxValue substitution into minimum number of test days D for corresponding stress levelminCalculating to obtain the theoretical minimum test days D of the corresponding stress levelminAs shown in the third column of table 1, again according to D ═ DminAnd calculating to obtain the corresponding stress testing days D in each stress group in the temperature and humidity stress level by adopting a/n calculation method, wherein the calculation result of D is a decimal and is further normalized into an integer as shown in a fourth column in the table 1.
TABLE 1 theoretical minimum days of testing at each stress level set
According to the test conditions, 2 temperature and humidity boxes are prepared, 60 tested sample tables are prepared (the sample tables and the sample tables installed on the site are the same production process), 30 sample tables are installed in each box, the voltage is 230V, the current is 10A, and the power factor is 0.8. The No. 1 box is tested according to the stress conditions of the temperature constant stress and humidity step stress group, the temperature is constant as the constant stress, the humidity is gradually increased from small to large as the step stress, the temperature is set to be 80 ℃, the humidity is initially set to be 85 percent, the humidity is adjusted to be 90 percent after the test is carried out for 28 days, the test is carried out for 24 days, and the test of the group is finished; the No. 2 box is tested according to the stress conditions of the temperature stepping stress and humidity constant stress group, the humidity is constant as the constant stress, the temperature is gradually increased from small to large as the stepping stress, the humidity is set to be 95%, the temperature is initially set to be 70 ℃, the temperature is increased to 75 ℃ after the test is operated for 32 days, the test is operated for 21 days, the temperature is increased to 80 ℃ after the test is finished, and the test is operated for 14 days, so that the group of tests are finished; and observing the failure condition of the tested sample every 24 hours, and if the failure phenomena of abnormal display, communication failure, data storage and reading failure or over-poor precision do not occur in the two groups of tests, judging that the failure rate of the batch of electric meters is lower than 5% after 10 years, and the confidence coefficient is the service life characteristic of 50%.
The invention provides an optimization test method on the basis of a constant stress accelerated life test and a stepping stress accelerated life test, wherein test conditions are specified according to life characteristics, and stepping stress is gradually increased from small to large, so that data arrangement and operation work is reduced, and labor cost is reduced; on the other hand, the test cost is saved by reducing 150 prototypes to 2 test devices and 60 prototypes from at least 5 test devices; moreover, the testing time is shortened from 94 days to 67 days at most, so that the development efficiency is improved; in general, the method is more practical and is convenient for manufacturers to evaluate the reliability of the products.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that are not thought of through the inventive work should be included in the scope of the present invention.
Claims (7)
1. A stepping stress accelerated life test method for evaluating reliability of an ammeter is characterized by comprising the following steps:
s1: selecting a certain number of electric meter samples to be tested from the batch of electric meters, and determining the service life characteristics of the batch of electric meters;
s2: temperature T according to batch ammeter installation environmentuAnd humidity RHuDetermining the stress level of the temperature and the humidity;
s3: calculating to obtain an acceleration factor AF according to the service life characteristics and the temperature and humidity stress level of the batch of electric metersmaxA value;
s4: according to an acceleration factor AFmaxCalculating the value to obtain the corresponding stress testing days D in each stress group in the temperature and humidity stress level;
s5: putting a certain number of electric meter samples to be tested into a temperature and humidity box for testing;
s6: observing the failure condition of the tested ammeter sample within a fixed time interval, if no failure occurs, continuing the test until the test is finished, indicating that the test result of the ammeter sample is qualified, and judging that the batch of ammeters meet the service life characteristics; if the test result is invalid, the test result of the electric meter sample is unqualified, and the batch electric meters are judged not to meet the service life characteristics.
2. The method as claimed in claim 1, wherein the lifetime characteristics of the electric meter to be tested in S1 are: after the electric meter works for Y years, the failure rate is lower than F%, and the confidence coefficient is CL.
3. The method of claim 1, wherein the temperature-humidity stress level in S2 includes a plurality of constant temperature stresses&Humidity step stress set, several temperature step stresses&A humidity constant stress set; constant stress at the temperature&Temperature T of humidity step stress setmHumidity RH as constant stressmAs step stress, constant stress at a temperature&Temperature T in humidity step stress setmIs a constant value, Tmin≤Tm≤TmaxHumidity RHmFor a number of stepwise increasing step values, i.e. RHmin≤RHm1＜RHm2＜……＜RHmn≤RHmaxN is the number of steps, i.e. the number of step stresses; constant stress of humidity&Humidity RH of temperature step stress setmAs constant stress, temperature TmAs step stress, constant stress at a humidity&Humidity RH in temperature step stress setmAt a constant value, RHmin≤RHm≤RHmaxTemperature T ofmFor a number of step-by-step increasing values, i.e. Tmin≤Tm1＜Tm2……＜Tmn≤TmaxAnd n is the number of steps.
4. The method as claimed in claim 1, wherein the acceleration factor AF in S3 is an acceleration factor AFmaxThe calculation formula is as follows:
wherein RH isuAnd RHSRelative humidity, T, under normal use conditions and stress conditions, respectivelyuAnd TSTemperatures under normal use conditions and stress conditions, respectively, expressed as thermodynamic temperatures, k being the Boltzmann constant, EaAnd N are two coefficients of the model, EaThe activation energy in electron volts was taken to be 0.9, and N was taken to be a constant, and 3 was taken.
5. The method for testing the accelerated lifetime of the stepping stress for evaluating the reliability of the electricity meter according to the claim 1 or 3, wherein the calculation formula of the corresponding stress testing days D of each stress group in the temperature and humidity stress level in S4 is as follows:
D＝Dmin/n
wherein Y is age, F is failure rate, UCL1Unreliable estimate of sequence number 1 for confidence CL, C is the contribution, β is the shape parameter, AFmaxIs the acceleration factor and n is the number of steps.
6. The method according to claim 1, wherein the step stress accelerated life test method for evaluating reliability of an electricity meter comprises the following steps of: putting a certain amount of ammeter samples to be tested into a temperature and humidity box, selecting a stress set for testing, wherein the stepping stress is gradually increased along with the time in the testing process, and all the tested samples are loaded with a voltage UnLoaded with a current of 0.1ImaxThe power factor is 0.5-1.
7. The method according to claim 2, wherein the step stress accelerated life test method for evaluating reliability of an electricity meter comprises the following steps of: observing the failure condition of the tested ammeter sample within a fixed time interval, if no failure occurs, continuing the test until the test is finished, indicating that the test result of the ammeter sample is qualified, and judging that the failure rate is lower than F% after Y years is met by batch ammeters, wherein the confidence coefficient is the life characteristic of CL; if the test result of the ammeter sample is unqualified, the batch ammeter judges that the fault rate is lower than F% after Y years are not met, and the confidence coefficient is the life characteristic of CL.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114966294A (en) * | 2022-07-27 | 2022-08-30 | 北京智芯微电子科技有限公司 | Reliability test system of power equipment, control method, device and medium |
| CN116804697A (en) * | 2023-06-25 | 2023-09-26 | 武汉敏芯半导体股份有限公司 | Aging condition acquisition method and system for laser chip and chip screening method |
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2021
- 2021-12-20 CN CN202111565018.2A patent/CN114624526A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114966294A (en) * | 2022-07-27 | 2022-08-30 | 北京智芯微电子科技有限公司 | Reliability test system of power equipment, control method, device and medium |
| CN116804697A (en) * | 2023-06-25 | 2023-09-26 | 武汉敏芯半导体股份有限公司 | Aging condition acquisition method and system for laser chip and chip screening method |
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