IEC 61508

IEC 61508 is titled "Functional safety of electrical/electronic/programmable electronic safety-related systems".The international standard IEC 61508 “Functional safety of electrical / electronic / programmable electronic safety-related systems (E/E/PES)” is intended to be a basic functional safety standard applicable to all kinds of industry. IEC 61508 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 standard covers the complete safety life cycle, and may need interpretation to develop sector specific standards. It has its origins in the process control industry sector.

The safety life cycle has 16 phases which roughly can be divided into three groups as follows: phases 1-5 address analysis, phases 6-13 address realisation and phases 14-16 address operation. All phases are concerned with the safety function of the system. The standard has seven parts. Parts 1-3 contain the requirements of the standard (normative), while 4-7 are guidelines and examples for development and thus informative.

Central to the standard are the concepts of risk and safety function. The risk is a function of frequency (or likelihood) of the hazardous event and the event consequence severity. The risk is reduced to a tolerable level by applying safety functions which may consist of E/E/PES and/or other technologies. While other technologies may be employed in reducing the risk, only those safety functions relying on E/E/PES are covered by the detailed requirements of IEC 61508.

IEC 61508 has the following views on risks:

*zero risk can never be reached
*safety must be considered from the beginning
*non-tolerable risks must be reduced (ALARP)

See also

* safety standards

External links

* [http://www.iec.ch/zone/fsafety/ IEC Functional safety zone]
* [http://www.safetyusersgroup.com Safety Users Group] - Functional Safety-Information Resources
* [http://www.insidefunctionalsafety.com Inside Functional Safety] - Technical magazine focusing on functional safety

Useful Papers

* [http://www.ldra.co.uk/nologindownload.asp?id=99 A revised proposal for IEC 61508. This paper was presented at the Embedded Systems Show 2006 in Birmingham, UK.]
* [http://www.nxtbook.com/nxtbooks/cmp/esd-europe0607/index.php?startpage=32 An article about meeting the IEC 61508 part 3 (software development) requirements for tool certification, specially compilers.]
* [http://www.exida.com/articles/IEc%2061508%20Cerftification.pdf Open IEC 61508 Certification of Products: This paper describes an assessment for product designs and the product development process that produces a full safety case as well as additional public documentation.]
* [http://www2.theiet.org/oncomms/sector/computing/Articles/Object/58D25FCD-6153-46BD-ADAF910D2C4B69D4 Overview of IEC 61508]