From a06d136ee40917308b3410e620defe1981c51339 Mon Sep 17 00:00:00 2001
From: Robin Clark <r.clark@energytechnologycontrol.com>
Date: Fri, 30 Sep 2011 13:53:38 +0100
Subject: [PATCH] more on FMEDA

---
 presentations/fmea/fmea_pres.tex | 45 +++++++++++++++++++++++++++++---
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/presentations/fmea/fmea_pres.tex b/presentations/fmea/fmea_pres.tex
index 88ccee8..45d0bfa 100644
--- a/presentations/fmea/fmea_pres.tex
+++ b/presentations/fmea/fmea_pres.tex
@@ -352,14 +352,53 @@ against all safe and dangerous failure probabilities.
 Again this is usually expressed as a percentage.
 
 $$ SFF = \big( \Sigma\lambda_S + \Sigma\lambda_{DD} \big) / \big( \Sigma\lambda_S + \Sigma\lambda_D \big) $$
+SFF determines how proportionately fail-safe a system is, not how reliable it is !
 
 \end{frame}
 
 \begin{frame}
 \frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis}
- SIL Levels are how they are calculated
+To achieve SIL levels, diagnostic coverage and SFF levels are prescribed along with
+hardware architectures and software techniques.
+Over all   the aim of SIL is classify the safety of a system,
+by statistically determining how frequently it can fail dangerously.
+
+
 \end{frame}
 
+\begin{frame}
+\frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis}
+{
+\begin{table}[ht]
+\caption{FMEA Calculations} % title of Table
+%\centering % used for centering table
+\begin{tabular}{|| l | l | c | c | l ||} \hline
+ \textbf{SIL} &   \textbf{Low Demand}     & \textbf{Continuous Demand}          \\ 
+              & Prob of failing on demand & Prob of failure per hour  \\ \hline \hline
+      4       & $ 10^{-5}$ to $< 10^{-4}$  &   $ 10^{-9}$ to $< 10^{-8}$                \\ \hline
+      3       &  $ 10^{-4}$ to $< 10^{-3}$ &    $ 10^{-8}$ to $< 10^{-7}$             \\ \hline
+      2       &  $ 10^{-3}$ to $< 10^{-2}$ &    $ 10^{-7}$ to $< 10^{-6}$             \\ \hline
+      1       &  $ 10^{-2}$ to $< 10^{-1}$ &    $ 10^{-6}$ to $< 10^{-5}$                        \\ \hline
+
+\hline
+\end{tabular}
+\end{table}
+}
+Table adapted from EN61508-1:2001 [7.6.2.9 p33]
+\end{frame}
+
+\begin{frame}
+\frametitle{ FMEDA - Failure Modes Effects and Diagnostic Analysis}
+FMEDA is a modern extension of FMEA, in that it will allow for 
+self checking features, and provides detailed recommendations for computer/software architecture.
+It also has a simple final result, a Safety Integrity Level (SIL) from 1 to 4 (where 4 is safest).
+
+FMEA can be used as a term simple to mean Failure Mode Effects Analysis, and is
+part of product approval for many regulated products in the EU and the USA...
+
+\end{frame}
+
+
 
 
 \section{FMEA used for Safety Critical Approvals}
@@ -410,9 +449,7 @@ judged to be in critical sections of the product.
   \pause \item FMEA type methodologies were designed for simple electro-mechanical systems of the 1940's to 1960's.
 \end{itemize}
 
-%FMEDA is a modern extension of FMEA, in that it will allow for 
-%self checking features, and provides detailed recommendations for computer/software architecture,
-%but
+%
 
 \end{frame}