IEC61508-2

COMMISSIONCEIELECTROTECHNIQUEIECINTERNATIONALE61508-2INTERNATIONALELECTROTECHNICALCOMMISSIONFunctionalsafetyofelectrical/electronic/programmableelectronicsafety-relatedsystems--Part2:Requirementsforelectrical/electronic/programmableelectronicsafety-relatedsystems61508-2ãIEC:1999265A/254/FDIS/c2CONTENTSFOREWORD..................................................................................................................................5INTRODUCTION.............................................................................................................................61Scope.......................................................................................................................................82Normativereferences................................................................................................................103Definitionsandabbreviations.....................................................................................................114Conformancetothisstandard....................................................................................................115Documentation........................................................................................................................116Managementoffunctionalsafety...............................................................................................117E/E/PESsafetylifecyclerequirements.......................................................................................127.1General............................................................................................................................127.2E/E/PESsafetyrequirementsspecification...........................................................................167.3E/E/PESsafetyvalidationplanning......................................................................................187.4E/E/PESdesign&development...........................................................................................197.5E/E/PESintegration...........................................................................................................367.6E/E/PESoperationandmaintenanceprocedures..................................................................377.7E/E/PESsafetyvalidation...................................................................................................387.8E/E/PESmodification.........................................................................................................397.9E/E/PESverification...........................................................................................................408Functionalsafetyassessment...................................................................................................42AnnexA(normative)TechniquesandmeasuresforE/E/PEsafety-relatedsystems:controloffailuresduringoperation.................................................................................................................43A.1General43A.2Hardwaresafetyintegrity....................................................................................................44A.3Systematicsafetyintegrity.................................................................................................53AnnexB(normative)TechniquesandmeasuresforE/E/PEsafety-relatedsystems:avoidanceofsystematicfailuresduringthedifferentphasesofthelifecycle...........................................................58AnnexC(normative)Diagnosticcoverageandsafefailurefraction....................................................66C.1Calculationofdiagnosticcoverageandsafefailurefractionofasubsystem..............................66C.2Determinationofdiagnosticcoveragefactorsforcomponents................................................67AnnexD(informative)Bibliography................................................................................................69Figures1Overallframeworkofthisstandard...............................................................................................92E/E/PESsafetylifecycle(inrealisationphase)...........................................................................1361508-2ãIEC:1999365A/254/FDIS/c23RelationshipandscopeforIEC61508-2andIEC61508-3............................................................134Relationshipbetweenthehardwareandsoftwarearchitecturesofprogrammableelectronics...........205Examplelimitationonhardwaresafetyintegrityforasingle-channelsafetyfunction........................256Examplelimitationonhardwaresafetyintegrityforamultiple-channelsafetyfunction.....................27Tables1Overview-RealisationphaseoftheE/E/PESsafetylifecycle.....................................................142Hardwaresafetyintegrity:architecturalconstraintsontypeAsafety-relatedsubsystems.............233Hardwaresafetyintegrity:architecturalconstraintsontypeBsafety-relatedsubsystems.............24A.1Faultsorfailurestobedetectedduringoperation......................................................................45A.2Electr