Application of IEC61508 in Railway
The author of this article was taken from the home of electromechanics
1 Application of Foreign Railways to IEC61508
While promoting and introducing the IEC61508 international standard, Western developed countries develop their own industry standards based on the IEC61508 international standard. The SC9XA committee of the European Commission for Electrification Standardization (CENELEC) has developed a railway signal standard (Figure 1) that uses a computer-controlled signal system as its object. It includes the following four parts:
(1) EN-50126 Railway Applications: Specifications, Specifications for Reliability, Availability, Maintainability, and Security (RAMS).
(2) EN-50129 Railway applications: Safety-related electronic systems.
(3) EN-50128 Railway applications: Software for railway control and protection systems.
(4) EN-50159-1 Railway applications: communication, signal and processing systems. Japan has already taken the lead in applying IEC61508. It first converted the IEC61508 international standard into the JIS-C-0508 national standard, and then the experts from the Japanese railway department, who have extensive experience in safety technology, formed the Train Security Control Security Technical Discussion Committee. A Safety Technical Guide for Train Security Control Systems was developed.
It can be seen that this railway safety standard is based on IEC61508 and has drawn on the experience of Japanese railway experts.
2 Application of IEC61508 in Railway Safety Related Systems
Our country should first absorb the essence of IEC61508, combine relevant international railway safety standards and railway safety standards and evaluation standards actually formulated by our country, and then establish a national railway safety assessment system. The following uses IEC61508 to conduct research on the development and development of railway safety-related systems and related safety document system and safety assessment system. There are two very important concepts in IEC61508, one is the level of safety and integrity, and the other is the safety life cycle. The determination of the level of safety and integrity requires the analysis of safety system risks. It is the goal and basis for system development and is the basis for assessing whether the system can guarantee safety. The safety life cycle describes how safety-related systems should be developed.
Figure 2 is a flow chart of IEC 61508 regarding the safety life cycle. It has important guiding significance for the development process of railway safety systems.
The Phase 1 concept has a certain degree of understanding of the safety-related system and its environment.
Phase 2 Overall Overview 1 Determine the boundaries of the control equipment and control system; 2 Describe the scope of the hazard and risk analysis.
Stage 3 Risk and Risk Analysis 1 Anticipate hazards and risk events; 2 Determine the severity of the events that lead to the hazards; 3 Determine the risk probabilities of controlling hazardous events.
Phase 4 defines the overall safety requirements. The requirements of each E/E/PE safety-related system are specified in detail based on the required safety function and safety integrity in order to complete the required safety functions.
Phase 5 Safety Requirements Assignment 1 Assign safety functions to designated E/E/PE safety-related systems; 2 Assign safety integrity levels to each safety function.
Phase 6 Develop an Overall Operation and Maintenance Plan Develop an operation and maintenance plan for the E/E/PE safety-related system to ensure that all required safety functions can be achieved in operation and maintenance.
The following items should be described in the plan: 1 General measures for realizing safety functions; 2 Countermeasures and requirements in special circumstances to prevent unsafe conditions; 3 Documents related to dangerous events; 4 Scope of maintenance; Necessary measures taken; 6 Directory of running and maintenance files written in chronological order.
Phase 7 Develop an overall safety verification plan Develop a plan for the E/E/PE safety-related system to carry out overall system safety verification.
Stage 8 Development of an overall installation and commissioning plan A plan is established for the installation and commissioning of the E/E/PE safety-related system to ensure that the required functional safety is achieved. The installation plan should include: the installation schedule, installation steps, responsible personnel, the sequence of installation of the different components, the standards for the installation, and the steps for troubleshooting.
The Phase 9 E/E/PE function implements the hardware for designing and implementing the E/E/PE safety-related system to meet the safety function and safety integrity requirements for the E/E/PE safety-related system.
Stage 10 The other technical implementation requirements are the same as stage 9.
The phase ll risk reduction measures meet the requirements of stage 9.
Stage l2 Overall installation and commissioning 1 Installation of E/E/PE safety-related systems; 2 Commissioning of E/E/PE safety-related systems.
Phase 13 Overall Safety Verification Demonstrates that the E/E/PE safety-related system meets the overall safety requirements specification in terms of functional safety and safety integrity.
Stage 14 overall operation, maintenance and repair To achieve the required functional safety, E/E/PE safety-related systems are to be operated, maintained and repaired.
Requirements: 1 For the operation of E/E/PE safety-related systems and software, maintenance and repair should be planned; 2 Initialization of the following actions: execution of steps, implementation of maintenance schedules, maintenance of documents, functional safety audits, For modified archives; 3 Prepare the files chronologically.
Phase 15 The overall modification and refurbishment ensure functional safety during modification and refurbishment. Requirement: 1 The approval of the request must be made, and the possible dangers, the suggestions for improvement and the reasons for the improvement must be listed in detail; 2 The consequences analysis should be carried out; 3 The approval of the modification and refurbishment depends on the result of the result analysis; 4 All Changes affecting functional safety should all be returned to the corresponding life cycle; 5 Archived in chronological order.
Stage 16 Retirement and Disposal Functional safety must be ensured during scrapping and recycling.
Requirements: 1 Analysis of the consequences of scrapping and recycling; 2 Recognizing and recognizing scrapped and recycled requests depends on the results of the analysis of the consequences; 3 Prepare a plan that includes downtime and steps to dismantle the E/E/PE safety-related system. 4 If scrapping and reclamation have an impact on functional safety, you should return to the appropriate safety lifecycle; 5 Archive in chronological order.
From the above introduction, we can see that the research and development process of the safety-related system required by IEC61508 is a complete and systematic process. Each phase is interlocked to form an organic whole. Figure 3 shows how to integrate the safety life cycle theory into the research and development of railway safety related systems by combining the actual conditions of railway applications.
From Figure 3 you can see the entire life cycle into a V-shaped, and is divided into four levels: user level, system level, subsystem level and component level. The opposite of safety is risk and failure. Before the design and development of safety-related systems, the system boundaries should be clearly defined. Hazard Analysis and Risk Analysis should be performed on the system to identify all possible safety hazards and dangerous patterns of the system. The gap between the current security level and the target security level of the system assigns the security perfection level requirements to each subsystem. When the system is designed and developed, corresponding countermeasures are taken to reduce the failure rate and satisfy the user's requirements for security. Analysis of hazards and risks in safety assessment is very important and directly affects the application of risk analysis techniques, the application of safety technologies, and the determination of the level of safety integrity. The main factors affecting risk and risk analysis are hazard identification methods, failure data, and consequences models. The safety assessment is based on a series of safety plans and specifications on the left side of the V-chart. The implementation of Phases 12 to 14 should refer to Phase 6 to Phase 8, respectively.
3 Security Document System
According to IEC61508, the security document system is also an important part of achieving system security and reliability. The necessary information of each stage of the safety life cycle is to be documented. The documents of the previous stage serve as the basis for the work of the next stage or later stages. The purpose is to effectively manage the functional safety demonstration and evaluation of all stages of the safety life cycle. . Requirements: (1) Details of each stage; (2) Detailed information on functional safety management; (3) Details required for functional safety assessment; (4) Documents should be clear, with titles and names; (5) Documents The structure should be easy to find relevant information; (6) There is a certain plan for the revision, review and approval of documents.
4 Safety Evaluation System
After completing the research and development of safety-related systems, it also involves the safety evaluation and approval of the entire system, ie safety assessment. It is to check whether the safety management of the project is complete and consistent with the safety plan. The security-related system is compared with the security requirements specification to evaluate whether it is enough to control the system risk and whether the system can meet the security requirement specification. The goal of the safety assessment is to investigate the level of functional safety of the E/E/PE safety-related system and arrive at a conclusion.
Claim:
(1) Participation of relevant personnel in the assessment In order to ensure the credibility of the assessment, the safety assessment personnel are required to have: 1 Engineering knowledge in the corresponding application areas; 2 Engineering knowledge and safety knowledge in the corresponding technologies; 3 Legal and safety standardization framework knowledge. In addition, the higher the fault level, the higher the SIL level and the stronger the required personnel ability.
(2) The assessor should be able to contact all personnel at all stages of the life cycle;
(3) The assessment shall adopt certain methods and means, and consider the following aspects: 1 The work done since the last functional safety assessment; 2 The recommendations of the last assessment; 3 The plans and strategies for the subsequent assessment;
(4) Assessment behavior should be consistent and planned;
(5) The functional safety assessment plan should state: 1 the person performing the assessment; 2 the result of each assessment; 3 the scope of the assessment; 4 the safety part included; 5 the required resources; 6 the independence of the assessor: individuals, departments Or institutions.
FRP Square Tube Rectangle Tube
FRP Square Tube Rectangle Tube,frp square pipe,FRP pultrusion profile,frp pultruded tube
Hebei Dingshengda Composite Material Co., Ltd. , https://www.dsdfrp.com