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IEC 61508
IEC 61508 is an international standard published by the International Electrotechnical Commission (IEC) consisting of methods on how to apply, design, deploy and maintain automatic protection systems called safety-related systems. It is titled ''Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems'' (E/E/PE, or E/E/PES). IEC 61508 is a basic functional safety standard applicable to all industries. It defines functional safety as: “part of the overall safety relating to the EUC (Equipment Under Control) and the EUC control system which depends on the correct functioning of the E/E/PE safety-related systems, other technology safety-related systems and external risk reduction facilities.” The fundamental concept is that any safety-related system must work correctly or fail in a predictable (safe) way. The standard has two fundamental principles: # An engineering process called the safety life cycle is defined based on best practices in order ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Standard
international standard is a technical standard developed by one or more international standards organizations. International standards are available for consideration and use worldwide. The most prominent such organization is the International Organization for Standardization (ISO). Other prominent international standards organizations including the International Telecommunication Union (ITU) and the International Electrotechnical Commission (IEC). Together, these three organizations have formed the World Standards Cooperation alliance. Purpose International standards may be used either by direct application or by a process of modifying an international standard to suit local conditions. Adopting international standards results in creating national standards that are equivalent, or substantially the same as international standards in technical content, but may have (i) editorial differences as to appearance, use of symbols and measurement units, substitution of a point for a com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IEC 62061
IEC/EN 62061, ”Safety of machinery: Functional safety of electrical, electronic and programmable electronic control systems”, is the machinery specific implementation of IEC/EN 61508. It provides requirements that are applicable to the system level design of all types of machinery safety-related electrical control systems and also for the design of non-complex subsystems or devices. The risk assessment results in a risk reduction strategy which in turn, identifies the need for safety-related control functions. These functions must be documented and must include: * Functional requirements specification * Safety integrity requirements specification The functional requirements include details like frequency of operation, required response time, operating modes, duty cycles, operating environment, and fault reaction functions. The safety integrity requirements are expressed in levels called safety integrity level (SIL). Depending on the complexity of the system, some or all of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Standards
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others. The presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges is an electric current and produces a magnetic field. When a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. If the charge moves, the electric field would be doing work on the electric charge. Thus we can speak of electric potential at a certain point in space, which is equal to the work done by an external agent in carrying a unit of positiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DO-178C
DO-178C, Software Considerations in Airborne Systems and Equipment Certification is the primary document by which the certification authorities such as FAA, EASA and Transport Canada approve all commercial software-based aerospace systems. The document is published by RTCA, Incorporated, in a joint effort with EUROCAE, and replaces DO-178B. The new document is called DO-178C/ED-12C and was completed in November 2011 and approved by the RTCA in December 2011. It became available for sale and use in January 2012. Except for FAR 33/JAR E, the Federal Aviation Regulations do not directly reference software airworthiness. On 19 Jul 2013, the FAA approved AC 20-115C, designating DO-178C a recognized "acceptable means, but not the only means, for showing compliance with the applicable FAR airworthiness regulations for the software aspects of airborne systems and equipment certification." Background Since the release of DO-178B, there had been strong calls by DERs (FAA Designated Eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Quality
In the context of software engineering, software quality refers to two related but distinct notions: * Software functional quality reflects how well it complies with or conforms to a given design, based on functional requirements or specifications. That attribute can also be described as the fitness for purpose of a piece of software or how it compares to competitors in the marketplace as a worthwhile product. It is the degree to which the correct software was produced. * Software structural quality refers to how it meets non-functional requirements that support the delivery of the functional requirements, such as robustness or maintainability. It has a lot more to do with the degree to which the software works as needed. Many aspects of structural quality can be evaluated only statically through the analysis of the software inner structure, its source code (see Software metrics), at the unit level, system level (sometimes referred to as end-to-end testing), which is in effect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-triggered System
Time-triggered architecture (abbreviated as TTA), also known as a time-triggered system, is a computer system that executes one or more sets of tasks according to a pre-determined and set task schedule.Pont, M.J. (2001) "Patterns for Time-Triggered Embedded Systems", Addison-Wesley / ACM Press. . Implementation of a TT system will typically involve use of a single interrupt that is linked to the periodic overflow of a timer. This interrupt may drive a task scheduler (a restricted form of real-time operating system). The scheduler willin turnrelease the system tasks at predetermined points in time. History and development Because they have highly deterministic timing behavior, TT systems have been used for many years to develop safety-critical aerospace and related systems.Ward, N. J. (1991) "The static analysis of a safety-critical avionics control system", in Corbyn, D.E. and Bray, N. P. (Eds.) "Air Transport Safety: Proceedings of the Safety and Reliability Society Spring Con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spurious Trip Level
Spurious trip level (STL) is defined as a discrete level for specifying the spurious trip requirements of safety functions to be allocated to safety systems. An STL of 1 means that this safety function has the highest level of spurious trips. The higher the STL level the lower the number of spurious trips caused by the safety system. There is no limit to the number of spurious trip levels. Safety functions and systems are installed to protect people, the environment and for asset protection. A safety function should only activate when a dangerous situation occurs. A safety function that activates without the presence of a dangerous situation (e.g., due to an internal failure) causes economic loss. The spurious trip level concept represents the probability that safety function causes a spurious (unscheduled) trip. The STL is a metric that is used to specify the performance level of a safety function in terms of the spurious trips it potentially causes. Typical safety systems that ben ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FMEDA
Failure modes, effects, and diagnostic analysis (FMEDA) is a systematic analysis technique to obtain subsystem / product level failure rates, failure modes and diagnostic capability. The FMEDA technique considers: * All components of a design, * The functionality of each component, * The failure modes of each component, * The effect of each component failure mode on the product functionality, * The ability of any automatic diagnostics to detect the failure, * The design strength (de-rating, safety factors) and * The operational profile (environmental stress factors). Given a component database calibrated with field failure data that is reasonably accurate, the method can predict product level failure rate and failure mode data for a given application. The predictions have been shown to be more accurate than field warranty return analysis or even typical field failure analysis given that these methods depend on reports that typically do not have sufficient detail information in failu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Standards
Safety standards are standards designed to ensure the safety of products, activities and processes, etc. They may be advisory or compulsory and are normally laid down by an advisory or regulatory body that may be either voluntary or statutory. In October 2021, a fire raging through multiple floors of a diplated apartment block in Kaoshiung highlighted the lax standards in Taiwan. China has recently experienced trouble with some of the post listed associations. Acts *Canada Consumer Product Safety Act * U.S. Consumer Product Safety Act See also * Consumer protection * Bicycle safety * China compulsory certification * Injury prevention * Public administration * Road safety * Standards organization * Testing organizations ** Baseefa (UK) ** Canadian Standards Association (Canada) ** Technischer Überwachungsverein (Germany, UK, China & USA) ** Underwriters Laboratories (USA) * Toy safety Toy safety is the practice of ensuring that toys, especially those made for children, are saf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Functional Safety
Functional safety is the part of the overall safety of a system or piece of equipment that depends on automatic protection operating correctly in response to its inputs or failure in a predictable manner (fail-safe). The automatic protection system should be designed to properly handle likely human errors, systematic errors, hardware failures and operational/environmental stress. Objective The objective of functional safety is freedom from unacceptable risk of physical injury or of damage to the health of people either directly or indirectly (through damage to property or to the environment) by the proper implementation of one or more automatic protection functions (often called safety functions). A safety system (often called a safety-related system) consists of one or more safety functions. Functional safety is intrinsically end-to-end in scope in that it has to treat the function of a component or subsystem as part of the function of the entire automatic protection function of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modified Condition/Decision Coverage
Modified condition/decision coverage (MC/DC) is a code coverage criterion used in software testing. Overview MC/DC requires all of the below during testing: #Each entry and exit point is invoked #Each decision takes every possible outcome #Each condition in a decision takes every possible outcome #Each condition in a decision is shown to independently affect the outcome of the decision. Independence of a condition is shown by proving that only one condition changes at a time. MC/DC is used in avionics software development guidance DO-178B and DO-178C to ensure adequate testing of the most critical (Level A) software, which is defined as that software which could ''provide (or prevent failure of)'' continued safe flight and landing of an aircraft. It is also highly recommended for SIL 4 in part 3 Annex B of the basic safety publication and ASIL D in part 6 of automotive standard ISO 26262. Additionally, NASA requires 100% MC/DC coverage for any safety critical software component i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Integrity Level
Safety integrity level (SIL) is defined as the relative level of risk-reduction provided by a safety function, or to specify a target level of risk reduction. In simple terms, SIL is a measurement of performance required for a safety instrumented function (SIF). The requirements for a given SIL are not consistent among all of the functional safety standards. In the functional safety standards based on the IEC 61508 standard, four SILs are defined, with SIL 4 the most dependable and SIL 1 the least. The applicable SIL is determined based on a number of quantitative factors in combination with qualitative factors such as development process and safety life cycle management. Assignment Assignment of SIL is an exercise in risk analysis where the risk associated with a specific hazard, that is intended to be protected against by a SIF, is calculated without the beneficial risk reduction effect of the SIF. That unmitigated risk is then compared against a tolerable risk target. The di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
