61508-6�IEC:19971Version4.005/12/97COMMISSIONCEIELECTROTECHNIQUEIECINTERNATIONALE61508-6INTERNATIONALELECTROTECHNICALCOMMISSIONFunctionalsafetyofelectrical/electronic/programmableelectronicsafety-relatedsystemsPart6:Guidelinesontheapplicationofparts2and361508-6�IEC:19972Version4.005/12/97ContentsForeword....................................................................................................................................6Introduction.................................................................................................................................81Scope...................................................................................................................................102Definitionsandabbreviations...................................................................................................12AnnexA(informative)Applicationofparts2and3........................................................................13A.1General........................................................................................................................13A.2Functionalsteps...........................................................................................................15AnnexB(informative)Exampletechniqueforevaluatingprobabilitiesoffailure.................................21B.1General........................................................................................................................21B.2Averageprobabilityoffailureperdemand(forlowdemandmodeofoperation).....................23B.2.1Procedureforcalculations..................................................................................23B.2.2Detailedtablesforlowdemandmodeofoperation................................................26B.2.3Examplesforlowdemandmodeofoperation.......................................................30B.2.4Architecturesforlowdemandmodeofoperation..................................................33B.3Probabilityoffailureperhour(forhighdem...
