"General Test Method for Temperature and Humidity Reliability of Communication Equipment" YD/T 282-2000 Introduction to Industry Standards

"General Test Method for Temperature and Humidity Reliability of Communication Equipment" YD/T 282-2000 Introduction to Industry Standards

Standard No. YD/T 282-2000 General name of general reliability test methods for communication equipment (Dongguan kowin testing equipment co.,ltd:temperature&humidity test chamber)

I. Work Overview
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The YD282 standard, "General Test Method for Reliability of Posts and Telecommunications Equipment" implemented in 1983, was formulated at a relatively early date and under the conditions of current technology and operational requirements. Therefore, some of the concepts cited in YD282-82 are Ideas have developed more than the original standards. Domestic and foreign standards have also been correspondingly developed and updated, such as MIL-STD-781D (GJB899-90), the guiding standard for reliability testing GJB 450-88, and various classification standards. All were updated or revised after 1986. After entering the 1990s, China’s communications industry has developed rapidly. The development of communications has also put forward new requirements for relevant standards, and requires more instructive test standards and more effective reliability design. Tests to ensure product quality and product reliability requirements. Through several years of reliability testing and research, combined with relevant data and testing techniques in Taiwan and abroad, combined with our actual experimental experience, we have made it more engineerable and easier to operate on traditional reliability tests. The main revised contents of the newly revised YD/T282 standard are as follows: 1. The title of the standard "General Test Method for the Reliability of Posts and Telecommunications Equipment". Based on the current development, it will be discussed and approved by the review and changed to the "General Test Method for Reliability of Communication Equipment". : Communication equipment temperature and humidity aging test; 2. Complete classification description of reliability test (temperature and humidity cycle test box); 3. According to the actual requirements of modern communication equipment on the test content, methods and failure judgments, fault classification, etc. The provisions were made to make it more engineering, practical and easy to implement. 4. According to the development trend of reliability engineering, the reliability assurance test and specific requirements were added; 5. The failures of the equipment in the test were graded; 6. Introduced the conditions and methods of field tests. ( R3 j$ m/ n y0 H
Second, the main content of the standard 's0 w, O8 `! M- M3 K

Compared with the original standard, this standard firstly introduces the GJB450-88 classification of reliability tests. That is, according to test sites, the equipment reliability test is divided into laboratory tests or field tests. The laboratory reliability test is a reliability test conducted under specified, controlled working environment conditions. The work environment can simulate or not simulate field conditions. The field reliability test is a reliability verification test or a measurement test conducted in the field. The on-site work environment, maintenance and measurement conditions need to be recorded. According to the requirements of various stages of development, production, and use of communication equipment, the reliability test consists of reliability engineering test and reliability statistical test. The reliability engineering test consists of an environmental stress screening (ESS) and a reliability growth test. It consists in exposing failures and eliminating them, usually during the development phase. Therefore, this standard only describes relevant concepts. The reliability statistical test has reliability verification test and reliability determination test. It is to verify whether the equipment meets the specified requirements and determine the reliability value it achieves. Generally, it is carried out in the development stage and the production stage. This standard applies to reliability statistical tests. Does not apply to environmental stress screening and reliability growth tests.
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This standard systematically describes reliability statistical tests. First of all, the test procedure, test plan and selection, performance testing and maintenance in the test, troubleshooting and calculation of reliability indicators, etc. are described first, and the failure classification and weighted failure numbers, and the total test time and confidence interval are emphasized. Calculations. The reliability test procedure focuses on the comprehensive environmental tests that should be performed and provides the stress conditions and time requirements that should be performed. For specific reliability appraisal tests, reliability acceptance tests, and reliability determination tests, step-by-step instructions are given according to test requirements and program selection, management of test procedures, and processing of test results, so that the test process is clear, refined, and Implementation: KOWIN temperature and humidity test box for communication equipment for high temperature test, low temperature test, high and low temperature cycle test, high and low temperature hygrothermal aging test, high temperature and humidity test, constant temperature and humidity test, temperature and humidity test and other simulation environment reliability certification.

Finally, the reliability assurance test is a more engineering test method. This standard system describes the test procedure, requirements and test time. Field tests are relatively easy to encounter in communications equipment, and the focus of on-site testing is the complete collection of data. This standard also provides a brief description. The main contents of the standard are as follows.

1. Reliability Test General Plan and Requirements
(1) Preparation before the test
Temperature and humidity aging of communication equipment (high-low temperature damp heat test) A reliability test plan shall be prepared before the reliability test. The test plan shall make full use of other tests in development and production to provide information and avoid duplication of test work. According to the requirements of the test plan and plan, test preparation is conducted, and a review of the test work is organized to determine whether the conditions for starting the test have been met and to ensure that the test equipment, test equipment, and all auxiliary equipment are all in a state ready to start testing. After the end of the test, the test results shall be reviewed in a timely manner to assess whether the test results are true and reliable. In order to ensure the smoothness of the reliability test and the accuracy of the results, the test equipment should be subjected to environmental stress screening. The test equipment and equipment shall ensure that the comprehensive environmental test conditions required for the production and maintenance of the tests are carried out, and shall be regularly checked and verified in accordance with the relevant regulations.
(2) Comprehensive environmental test conditions
The comprehensive environmental test conditions and the corresponding time shall be determined according to the on-site use requirements and task environment characteristics of the tested equipment, simulate the main stress experienced by the tested equipment during use, and simulate the environmental conditions and use conditions of the equipment used during the test. The test equipment should work under typical operating conditions and load conditions. Test conditions can be integrated with stress, or according to equipment technical standards or test environment conditions as specified in the contract.
(3) Statistical test plan and selection
This standard stipulates two kinds of test schemes: namely, the timing cut-off test scheme and the cut-off sequential test scheme. The test time of the censored test program is random, but on average it can refer to the timed censored test program.
1 Selection of test plan

General principles for the selection of test protocols:
When it is necessary to know the exact total test time and the test cost, the timing cut-off test scheme is selected.
If there is a normal producer and consumer risk rate (10% to 20%) and there is no strict requirement on the accuracy of the total test time, for equipment with good quality or with very poor quality or very few samples, Censored sequential tests can be used. Generally choose α = β.
2 The number of tested devices
The parent device of the test device must be produced according to the same design document and production process. The test device can be randomly selected from the mother device. The number of samples is generally at least two, but if the number of production is less than three, the sampling allowable amount may be one.

(4) Performance testing and maintenance in tests
Both before and after the test, performance tests shall be carried out under the standard atmospheric conditions specified in 5.3 of GB/T 2421-1989 and the requirements for the items and parameters to be tested during the test shall be specified.

1 The performance measurement of the communication equipment before the high temperature and high humidity test should be performed after the test equipment is loaded into the test equipment to avoid introducing faults during the installation. The performance test shall comply with the specifications of the EUT and be used as a benchmark for comparison with the measured performance during the test and at the end of the test.

Conditional testing should be continuous. If the performance test cannot be performed continuously during the test, the measurement interval should be specified. In principle, the test should be conducted under extreme conditions. The number of tests can not be less than twice during the entire test period.

At the end of the constant temperature and humidity test of the communications equipment, the performance of the tested equipment shall be measured and recorded to determine whether the performance of the tested equipment meets the requirements of its specification and standards.

2 Maintenance during testing
In the high-low temperature wet heat reliability verification test, the communications product may carry out the preventive maintenance procedures listed in the test procedures for the test equipment, but no additional maintenance is allowed. To ensure the completion of the test, preventive maintenance of the test equipment can be performed.
(5) Failure Analysis, Processing, and Correction
1 Fault classification is based on the mission reliability of the equipment. Faults are classified as related faults and non-associated faults. Non-associated faults are not used as the basis for the qualification of the test equipment, and associated faults should be further divided into liability faults and non-burden faults. In view of the complexity of the communication equipment, the failure situation has different effects on the equipment's fulfillment of its prescribed functions, so it can be divided into the following three levels according to the severity of the equipment's impact. The level of each type of failure shall be determined before the test in accordance with the above-mentioned principles and requirements of the functions and indicators of the tested equipment.   

2 Determine the time required for failure
When the test device finds the same fault in discontinuous detection, if the fault cannot be accurately determined, it should be considered that the fault occurred within the last detection time.
3 Failure Report, Analysis and Correction
Closed-loop systems should be used to collect reliability verification, all failure data that occurred during the test, analyze the causes of these failures, take corrective measures and verification of these failures, and make a record.

(6) Calculation of total test time and reliability index
When the time-based censoring test scheme is adopted, the total test time of the test equipment will stop when the time specified in the specified test plan is reached; or the total test time does not reach the time specified in the plan, but the number of failures is greater than or equal to the specified in the table. If you reject the decision, you can also stop the trial.
Sequential test time should be designed based on the maximum allowable test time (truncated time). According to the total test time and cumulative failures and the table in the provisions of the acceptance, rejection criteria for comparison, if you can make a decision to accept or reject, you can stop the test.

For the censored number test, when the number of failures is determined, the test stops when the specified number of failures is reached.

1 Calculation of weighted failures
According to the classification of liability fault severity, if theoretically a weighted value can be derived, it is weighted according to the theoretical value. If there is no other basis, the following weighting values ​​are recommended:
A failure: W1=1;
Secondary failure: W2=0.2~0.5;
Level 3 failure: W3=0.01~0.1.
2 Calculation of total test time
The total time T for the equipment test is generally calculated as follows: n samples taken are subjected to a life test under the specified conditions, and are stopped at the specified time t. The total time is then n times the total sample test time t. If there is a failure in the sample during the test, immediately after the repair, continue the test, such as formula 1; if not repair and remove the fault sample, other samples continue to test, stop at the specified time t, the total time as formula 2.
T=nt (1) %
T=(nr)t+ (2)
Where: n - total number of samples tested
t - Test cut-off time
r - number of failed samples
ti——Time before fault sample failure
3 Mean Time Between Failures (MTBF) Estimates
If a fault occurs, the MTBF observation can be calculated by dividing the total test time by the number of weighted faults.
MTBF=T/rW (3)
Where: T - total test time  
rW - Weighted Failures

(7) Test records and test reports
In the reliability verification test, the relevant test data should be completely recorded. The test records shall include equipment descriptions, test data and results before and after the test, and failure records, maintenance records, and corrective action reports.
2. Reliability test
According to the method and purpose of reliability statistical test, reliability statistical test can be divided into reliability verification test and reliability test. A reliability test is a test that is performed to determine reliability characteristics or their magnitude. It is usually used to provide reliability data. The reliability verification test is a test used to verify whether the reliability characteristic value of the equipment meets its specified reliability requirements. Generally, the reliability identification and acceptance test are collectively referred to as reliability verification tests.
(1) Reliability qualification test
In order to verify that the equipment design meets the requirements of the specified reliability index, the equipment used to represent the approved technical status shall be subjected to the reliability identification test under the specified comprehensive environmental test conditions. The reliability qualification test is a test performed after the design is completed to determine whether the equipment meets the specified reliability index under the specified environment and working conditions. Contents include test requirements, test environment conditions, requirements of test equipment, determination of test plans, management of test procedures, troubleshooting, classification and discrimination of faults, and judgments of passing or not.
(2) Reliability acceptance test
The reliability acceptance test is to test the delivered batch equipment under the specified conditions to verify that the delivered equipment meets the specified reliability requirements. The inspection lot is constituted according to the production conditions, and the equipment is randomly selected from the inspection lot, and the reliability acceptance test is performed under the same comprehensive environmental test conditions as the reliability qualification test. Including the test requirements, test environment conditions, test equipment requirements, the determination of the test program, the management of the test process, fault classification and discrimination, data processing after the test, batch receiving and batch rejection.
(3) Reliability Test 8
The purpose of the reliability test is to measure the reliability of the equipment. The content includes test requirements, performance testing and maintenance during test, test plan, and estimation method of reliability characteristic values. That is, regardless of the repair or replacement of faulty equipment, the failure rate, average time before failure, and average failure can be obtained through tests. Point estimates and confidence intervals for intervals. According to the test time and the number of failures, the observed value of MTBF can be calculated according to formula (3). If the reliability determination test is to put some equipment into a test that does not specify a predetermined cut-off procedure, the reliability is estimated at any time based on cumulative test time and number of failures.

(4) Reliability Assurance Test
When the equipment reliability index is quite high, or the sample size of the equipment is relatively small, when the reliability test is conducted, the schedule and the expenses cannot be arranged. Or when the equipment has considerable maturity and the quality is very stable, the reliability acceptance test can be replaced by a reliability assurance test plan, with the consent of the user.
The reliability assurance test is a reliability acceptance test performed after the equipment has passed Environmental Stress Screening (ESS). Contents include test conditions, time to failure (t) determination and test procedures.
(5) Field test
In communications equipment, some tests must be conducted under field conditions and environmental conditions. Field tests can be used. The field use was used as a field test to statistically analyze the operating data of the equipment and verify the reliability of the equipment. Content includes test conditions, data collection, and data processing.

Third, the main reference standards and literature:
"Reliability verification method for ship system and equipment *XXXX" June 1993
"Reliability Design Handbook"  
"Credibility Engineering" He Guowei March 1997
"Reliability Maintenance Standard Application Guidance" 1995
GB 5080.1-86 Equipment Reliability Test General Requirements
GB 5080.4-86 equipment reliability test Point estimation and interval estimation method for reliability determination test (exponential distribution)  
GB 5081-85 Data Collection Guide for Reliability, Validity, and Maintainability of On-site Electronic Products
GB 4798.1-86~4798.10-91 Electrical and Electronic Products Application Environment Conditions
GB/T 13426-92 reliability requirements and test methods for digital communication equipment
GJB 150.1~150.20-86 Military Equipment Environmental Testing Methods
GJB 450-88 General Outline for Reliability of Equipment Development and Production
GJB 451-90 Reliability Maintainability Terms
GJB 841-90 Fault Reporting, Analysis and Corrective Action System (FRACAS)
GJB 899-90 Reliability Qualification and Acceptance Test
GJB 1032-90 Electronic Product Environmental Stress Screening Method
GJB 1407-92 Reliability Growth Test
Compared with the above standards, this standard pays more attention to the implementability of the test method to ensure the correctness of the standard content. The discussion of the test method is combined with relevant information and experience, making the reliability test method can have a positive guiding significance. . ,

Fourth, the implementation of the standard recommendations
Because the content of YD282 has not been updated for a long time, the role of the document as a guide has not been truly reflected. The current development of the communications industry is very rapid, and the requirements for the use of equipment are getting higher and higher. Actually, there are different opinions on the determination of reliability indicators. The reliability of some manufacturers' equipment is still blank. Therefore, the implementation of this standard proposes to first increase the assessment of comprehensive environmental testing in the new network inspection to ensure that the basic use of communication products can meet the requirements of the telecommunications network, and that all manufacturers will gradually carry out reliability verification tests according to this standard development plan. Improve product stability. At the same time, more explicit guidance should be given for the determination of reliability indicators of communications equipment and related maintenance requirements. In conjunction with the implementation of this standard, the requirements of telecommunications networks can be truly satisfied.

Fifth, other instructions
Because there are many types of communication equipment, this standard only provides general reliability test methods and results determination instructions. However, for specific communication equipment, its determination standards and requirements cannot be described. Therefore, specific communication equipment must be developed accordingly. Working conditions and detailed requirements for invalidation decisions.