This commit is contained in:
Robin 2010-03-27 04:15:05 +00:00
parent 5b27854f7a
commit 9fce93fdce
2 changed files with 17 additions and 8 deletions

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@ -362,9 +362,11 @@ The PT100 circuit can now be treated as a component in its own right, and has on
Using the MIL1991\cite{mil1991} specifications for resistor and thermistor
failure statistics we calculate the reliability of this circuit.
MIL1991 gives MTTF for a wide range of common components.
It does not specify how the components will fail (in this case OPEN or SHORT).
RIAC does specify that resistors are expevcted to fail OPEN in 90\% of cases and SHORTED
in the other 10\%, so we can use this.
It does not specify how the components will fail (in this case OPEN or SHORT). {Some standards, notably EN298 only consider resistors failing in OPEN mode}.
FMD-97 Gives 27\% OPEN and 3\% SHORTED, for resistors under certain electrical and environmental stresses. This example
compromises and uses a 90:10 ratio, for resistor failure.
Thus for this example resistors are expevcted to fail OPEN in 90\% of cases and SHORTED
in the other 10\%.
A standard fixed film resistor, for use in a benign environment, non military spec at
temperatures up to 60\oc is given a probability of 13.8 failures per billion ($10^9$)
@ -414,7 +416,7 @@ be the fault~mode we would scrutinise first.
\begin{figure}[h+]
\centering
\includegraphics[width=400pt,bb=0 0 856 327,keepaspectratio=true]{./stat_single.jpg}
\includegraphics[width=400pt,bb=0 0 856 327,keepaspectratio=true]{./pt100/stat_single.jpg}
% stat_single.jpg: 856x327 pixel, 72dpi, 30.20x11.54 cm, bb=0 0 856 327
\caption{Probablistic Fault Tree : PT100 Single Faults}
\label{fig:stat_single}

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@ -56,15 +56,22 @@
\chapter{Statistical Methods and Models}
%\input{statistics/statistics}
\chapter{Survey of Safety Critical Analysis Metyhodologies and Tools Available}
%\input{survey/survey}
\chapter{Survey of Safety Critical Analysis Methodologies and Tools Available}
\input{survey/survey}
\typeout{ ---------------- Component Failure Modes Definition }
\chapter { Component Failure Modes Definition}
\input{component_failure_modes_definition/component_failure_modes_definition}
\typeout{ ---------------- Propositional Logic Diagrams}
\chapter {Propositional Logic Diagrams}
\input{logic_diagram/logic_diagram}
\typeout{ ---------------- Electronic Components as PLDs}
\chapter {Electronic Components as PLDs}
\chapter {Common Electronic Components as PLDs}
\input {components_as_plds/components_as_plds}
\typeout{ ---------------- Software as PLDs}
@ -72,7 +79,7 @@
\input{sw_as_plds/sw_as_plds}
\typeout{ ---------------- Mechanical Sub-systems as PLDs}
\chapter {Mechanical Sub-systems as PLDs}
\chapter {Common Mechanical Sub-systems as PLDs}
%\input{mech_as_plds/mech_as_plds}