IEC 61508 standard
IEC 61508 standard - Functional safety of electrical/electronic/programmable electronic safety-related systems
IEC 61508 is an international standard covering issues that must be taken into consideration when designing electrical, electronic and programmable electronic safety-related systems. IEC 61508 is a universal standard of functional safety and can be applied in every sphere of industry. It allows one to fully consider crucial factors related to tasks being fulfilled and therefore satisfy particular needs of the scope it is being used in. Another purpose of this standard is to enable development of electrical, electronic and programmable electronic safety-related systems in conditions of possible absence of standards for particular areas.
The central points of the IEC 61508 standard are the notions of risk and safety functions. Risk is a function of the possibility of a potentially dangerous event and the severity of its consequences. Risk may be reduced to admissible levels by applying safety functions. The standard accepts the following assumptions concerning risk:
- Zero risk cannot be achieved
- Security must be estimated since the beginning of design process
- Inadmissible risks must be reduced to the minimum practically possible values
The IEC 61508 standard specifies the static analysis methodology as one of the basic methodologies for safety confirmation and ruling out systematic failures for E/E/PE systems. This methodology allows one to examine particular static characteristics of prototype models of a system for providing completeness, consistency and absence of ambiguities concerning defined requirements.