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AMNYTT # 6 2016 the safety logic solver is configured to detect Low failure and does not automatically trip on this failure , this failure has been classified as a dangerous detected ( DD ) failure ;
• fail “ No Effect ”: failure mode of a component that plays a part in implementing the safety function but that is neither a safe failure nor a dangerous failure . When calculating the SFF , this failure mode is not taken into account ;
• fail “ Not part ”: failure mode of a component which is not part of the safety function but part of the circuit diagram and is listed for completeness . When calculating the SFF this failure mode is not taken into account .
The 2 channels of the D5014D module could be used to increase the hardware fault tolerance , needed for a higher SIL of a certain Safety Function , as they are completely independent from each other , not containing common components . In fact , the analysis results for D5014S ( single channel ) are also valid for each channel of D5014D ( double channel ). This analysis is also valid for D5014D as Duplicator of 2 wires Transmitter Input Signal , but considering safety function is only applied to the channel configured as passive input . Failure rate data : taken from Siemens Standard SN29500
Sikkerhetsmanualen skal også gi en oppsummering av feilraten : Tabellen nedenfor forutsetter et resultat på T-proof-testen = 99 %. Dette vil ikke være praktisk uten råd og veiledning om hvordan testen skal utføres !