Safety Integrity Level

Safety Integrity Level (SIL) определяет соответствующий уровень уменьшения опасности от возникновения аварий и катастроф, обеспечиваемый функционалом средств и систем повышенной безопасности или указывает целевой уровень уменьшения риска возникновения опасной ситуации.

Four SIL levels are defined, with SIL4 being the most dependable and SIL1 being the least. A SIL is determined based on a number of quantitative factors in combination with qualitative factors such as development process and safety life cycle management. The requirements for a given SIL are not consistent among all of the functional safety standards.

IEC 61508 и IEC 61511

The international standard IEC 61508 defines SIL using requirements grouped into two broad categories: hardware safety integrity and systematic safety integrity. A device or system must meet the requirements for "both " categories to achieve a given SIL.

The SIL requirements for hardware safety integrity are based on a probabilistic analysis of the device. To achieve a given SIL, the device must have less than the specified probability of dangerous failure and have greater than the specified safe failure fraction. These failure probabilities are calculated by performing a Failure Modes and Effects Analysis (FMEA). The actual targets required vary depending on the likelihood of a demand, the complexity of the device(s), and types of redundancy used.

The SIL requirements for systematic safety integrity define a set of techniques and measures required to prevent systematic failures (bugs) from being designed into the device or system. These requirements can either be met by establishing a rigorous development process, or by establishing that the device has sufficient operating history to argue that it has been proven in use.

Electric and electronic devices can be certified for use in functional safety applications according to IEC 61508, providing application developers the evidence required to demonstrate that the application including the device is also compliant.
IEC 61511 это специфическая отраслевая адаптация стандарта IEC 61508 для непрерывных процессов. Этот стандарт, помимо прочего, используется в нефтеперерабатывающей, нефтехемической и химической промышленности.

SIL в других стандартах

Следующие стандарты также используют понятие SIL (определяемое отлично от указанного), как меру надёжности или уменьшения риска:
*EN 50128
*EN 50129
*Defence Standard 00-56 Issue 2

Ссылки

* [http://www.fersil.fr/html/ferroviaire_surete_fonctionnement_normes_en.html Fersil : Operational Safety: SIL Standards]
* [http://www.iec.ch/functionalsafety IEC Functional safety zone]
* [http://www.iec.ch/zone/fsafety/pdf_safe/hld.pdf Functional Safety and IEC 61508: A basic guide]
* [http://www2.theiet.org/oncomms/sector/computing/Articles/Object/58D25FCD-6153-46BD-ADAF910D2C4B69D4 Overview of IEC 61508]
* [http://www.dynatorque.com/dstop/ DynaTorque D-Stop Partial Stroke Test Device]
* [http://www.safetyusersgroup.com Safety Users Group] - Functional Safety-Information Resources