TB/T 2468-2018 in English
VALIDEvaluation methods of railway signal product reliability
- Issued on:2018-06-05
- Implemented on:2019-01-01
- File Format:PDF
- Delivery:Via email within 5 business days
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| Standard No: | TB/T 2468-2018 |
| Document status: | VALID |
| Title in English: | Evaluation methods of railway signal product reliability |
| Title in Chinese: | 铁路信号产品可靠性要求评定方法 |
| Language: | English |
| File Format: | Electronic (PDF) |
| Delivery: | Via email within 5 business days |
| Issued on: | 2018-06-05 |
| Implemented on: | 2019-01-01 |
| Superseding: |
TB/T 2468-1993 Assessment Method for Reliability Requirements of Railway Signal Product
|
| Professional Classification: | TB-Railway Transport |
| Related Topics: | product reliability
product reliability TB/T 3474.2-2018 Swimming Reliability Test Method for Electronic Products tb/t3539-2018 |
Introduction
Interpretation of the core content of the standard
This standard replaces TB/T2468-1993. The main technical changes include: adding 22 new term definitions, optimizing the test plan calculation method, introducing statistical tools such as the χ² distribution table, and refining the test methods for special products such as electronic equipment and relays.
Key Terminology
| Terminology | Definition | Application Scenarios |
|---|---|---|
| MTBF | Mean time between failures, a core reliability indicator for repairable equipment | Repairable products such as relays and switches |
| MTTF | Mean time before failure, a reliability indicator for non-repairable equipment | Disposable products such as signal light bulbs |
| Failure rate λ | The ratio of the failure probability density function to the reliability per unit time | Grade assessment of electronic components |
Comparison of Reliability Test Schemes
| Test Type | Applicable Scenarios | Advantages | Risk Control |
|---|---|---|---|
| Timed Truncation Test | Mandatory certification requiring a fixed verification cycle | Accurate calculation of confidence intervals | α,β≤10% |
| Sequential Truncation Test | Rapid verification in the R&D phase | Save an average of 30% testing time | Actual risks may exceed the standard |
Note: The selection of a solution requires a comprehensive consideration of the discrimination ratio (D) (recommended 1.5-3), risk level, and cost.
MTBF Calculation Method
MTBF point estimate formula for a timed censored test:
θ̂ = T*/r
Where T* is the total test time and r is the number of associated failures. The confidence interval is calculated using the quantile of the chi-squared distribution, using a chi-squared distribution with 2r degrees of freedom for rejection and 2r+2 degrees of freedom for acceptance.
Key points for on-site data statistics
- At least 11 basic data items must be recorded, including equipment ID, commissioning time, failure mode, etc.
- Calculation of cumulative working time: T* = Σti (i=1→n)
- Only fatal/serious failures are counted, and non-correlated failures caused by external factors are excluded.
Specific product test requirements
Electronic equipment
Temperature cycling requirements: Each cycle includes 2h high temperature (85%RH) and 2h low temperature stages, with a rate of change ≤1℃/min
Signal relays
Perform failure rate test according to GJB2649A, with the number of samples n=T/ti (ti≥2 times the index value)
Signal Light Bulbs
Accelerated test formula: C=(13.2/12)14≈3.8. Test time can be shortened to 26% at 110% voltage.
Standard Implementation Recommendations
- Sequential test plan (Scheme 3, D=3) is preferred for new product development.
- A high-risk control plan with α=β=10% is recommended for key equipment.
- A standardized collection system should be established for field data to ensure data traceability.
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