exida explains Blog

Entries tagged with: Fmeda

2012 - Good Progress for Cybersecurity and Functional Safety

I think it is wise for individuals to periodically review things. I like to do my professional review at the end of the year. 2012 was a good year.

Product Certification

Over 60 new products received functional safety or cybersecurity certification this year. Those products and more…

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  • by Michael Medoff , CFSE, CISA
  • Thursday, September 20, 2012
  • Certification

Component De-rating Without the Overhead

If you were going to build a bridge, you would want to make sure that it did not fall down if there were too many cars on the bridge.  One way that this is accomplished is to overdesign.  If the bridge is expected to hold at most 20,000 pounds,…

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Field Failure Rate: 10 FITS or 1000 FITS?

After analyzing field failure data from hundreds of data sets from dozens of sources, it is becoming easy to see why results from different studies may vary by an order of magnitude or more. The data collection process itself varies by an order of magnitude or more!  A few…

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Getting Good Proof Test Coverage Numbers

Getting Good Proof Test Coverage Numbers

Several years ago we recognized that proof test coverage was an important variable that must be considered when doing PFDavg calculations. We ran some models and discovered that the difference between “perfect” proof test coverage (100%) and a very good 90% could mean a whole SIL

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How to Decode an exida IEC 61508 Certificate: Part 1

So you downloaded a product certificate from the exida website and you are trying to understand the information documented in the certificate.  Also, you likely want to know what stands behind the certificate and what was involved in the certification of the product.
 
I’m not…

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How to Decode an exida IEC 61508 Certificate: Part 2

Click here to read Part 1

Now that you know the step-by-step process of product certification, now let’s take a look at the actual information on the certificate. 

In the left panel (gray background) you will find an exida certification logo. …

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Replace Before Failure

The solenoid valve manufacturer provides an FMEDA report that lists “useful life = 12 years.”  Useful life is a reliability engineering term that indicates a point in time when the failure rate of a device will begin increasing rather rapidly.  Why do we care about this time interval?  That…

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  • by Dr. William Goble, CFSE
  • Friday, March 04, 2011
  • Certification

Tales from the Certification Wars - Proven In Use versus Certification

The Battle of the Failure Rates

Site Specific vs. Product Specific

During a field failure analysis study, it was discovered that the calculated failure rate of a specific device varied by more than 4X depending on installation site.  Particularly, it was one specific site with a high failure rate.  While any reliability engineer…

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  • by Dr. William Goble, CFSE
  • Wednesday, February 27, 2013
  • Software

The Real PFDavg Variables

I was recently asked how the PFDavg value in an exida FMEDA report was calculated. Those PFDavg values are calculated using the exSILentiaTM program. The person who posed the question was using the equations from Part 6 of IEC 61508 and got a different value. Why?

exSILentia

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Two Billion Hours

When I studied Reliability Engineering in graduate school, I was taught that failure rate data came from field failure studies.  I assumed that operating companies always kept accurate records when a piece of equipment failed.  I also assumed that someone would investigate the failures and assign a root cause.…

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Welcome to the 2H Initiative

exida has been gathering field failure data for over a decade.  At this point we have a total of over 60 billion unit operating hours of field data for process industry devices.  This data has been used to create a 2H database for components.  exida is using this component…

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