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3. Main assumptions and mathematical bases of ADD
From a mathematical point of view, an ADD is an acyclic directed graph, i.e. between the inputs (primary events) and the output (undesired event), it has no loops or feedbacks. It is based on the following fundamental assumptions:
the system has only two states, e.g. on/off, and the undesired event at the top of the tree generally corresponds to the system's failure state;
the system components have only two states, e.g. on/off, and the primary events generally correspond to the failure states of the components;
the ADD represents the logical function linking the primary events to the undesired event. That is, in general, the failure state of the system to the failure states of its components;
the primary events are independent of each other....
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Main assumptions and mathematical bases of ADD
Electrical analogy and concepts of minimum closure and disconnection paths
Bibliography
Software tools
GRIF-Workshop software package (GRaphique Interactif pour la Fiabilité), developed by ELF and then for TOTAL by SATODEV.
module Tree: fault trees ;
ETree module: event trees ;
SIL module: BDF adapted to functional safety ;
Petri module: stochastic Petri nets ;
...
Standards and norms
- - CEI 61078 -
- - CEI 60050-192 -
- - CEI 61703 -
- - ISO/TR 12489 -
- - CEI 61025 -
- - CEI 61165 -
- - CEI 62551 -
- - CEI 61508 -
- - CEI 61511 -
- - CEI 62740 -
- - CEI 62502 -
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International Electrotechnical Commission IEC (IEC)
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