Dr. William Goble's photo
Dr. William Goble, CFSE

Setting the Pace

Thursday, May 02, 2013

Going back in time to the turn of the century (remember 2000?), the amount and quality of failure data threatened to doom the whole probabilistic analysis approach.  I recall a letter in IEEE Spectrum magazine from Patrick D. O’Conner, a well known reliability engineering author, who expressed the opinion that IEC 61508 was a unless burden that would force widespread waste of engineering time. 

We at exida recognized that probabilistic analysis had great potential to allow companies to improve safety while actually lowering cost however more realistic models and failure data were needed.  We have studied hundreds of field failure data sets and incident reports for more than a decade.  The first thing to become clear was that…

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Dr. William Goble's photo
Dr. William Goble, CFSE

Make IEC 61511 into a Cookbook?

Thursday, May 30, 2013

IEC 61508 and IEC 61511 are known as “performance” based standards.  Specific design rules, as found in “prescriptive” standards, are not included, allowing for innovation and new technology, as well as creativity and advancement.  However, it does imply that a certain level of competency is required.

Others would strongly argue that IEC 61511 should eliminate the requirement for performance calculations and replace them with a set of standard designs that must always be implemented the same way.  I have heard people say “You need a PhD in Reliability Engineering to do those calculations.”  Well I do have a PhD in Reliability Engineering, so I understand the comment when thinking about the situation in the 1990s.  But today things are different. …

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