exida explains Blog

Entries tagged with: Dr. William Goble

  • by Dr. William Goble, CFSE
  • Thursday, January 12, 2012
  • News

2011…A Year in Review

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…

Read More...

  • by Dr. William Goble, CFSE
  • Wednesday, April 03, 2013
  • Certification

A 100% Pass Rate!

I recently read a blog comment from an instructor in a well-known functional safety personnel certification program.  The instructor bragged that for the last X courses, 100% of the students passed.  In this program a course and an exam are developed by independent consultants who give the course, give…

Read More...

A Year in Review: Functional Safety and Cybersecurity in 2015
  • by Dr. William Goble, CFSE
  • Tuesday, January 26, 2016
  • Certification

A Year in Review: Functional Safety and Cybersecurity in 2015

Good things happened in the fields of functional safety and control system cybersecurity in 2015.  I am not going to include the exciting new Star Wars movie as an event in the list as it does not really fit into the topic. But keeping focused, my highlights is 2015…

Read More...

Are All Field Devices Type A?

Are All Field Devices Type A?

I was told by an end user engineer that he considers all field devices to be simple Type A devices.  In IEC 61508, Type A is defined as a device with well-defined failure modes, well known failure rates, and behavior under fault conditions that can be completely determined.  Type…

Read More...

  • by Dr. William Goble, CFSE
  • Thursday, May 12, 2011
  • Certification

Buy Certified Equipment, Meet the Standard, Right? WRONG!

Can Wireless be used in Functional Safety?

Can Wireless be used in Functional Safety?

exida just completed certification of a new sensor product that uses wireless communication to signal a safety logic solver of a potential problem.  Shortly after the certificate was posted, a challenge arose:  “How can wireless be used for safety?”  Well, it is different.  A designer must be fully…

Read More...

  • by Dr. William Goble, CFSE
  • Thursday, May 09, 2013
  • Certification

Certificate Forgery!

exida has discovered yet another forged functional safety certificate.  You can read about another occurrence in a previous blog entry.

False Certificate


The company name on the forged certificate is ISP SA DE CV, Cunduacan, Tab., Mex.  How could someone…

Read More...

  • by Dr. William Goble, CFSE
  • Thursday, November 15, 2012
  • Certification

Certification Accreditation

I am often asked “who says exida can certify a product?”  The best answer is of course “the marketplace.”  End user owner/operators ask for an exida certificate because they understand why technical competency is so important when evaluating design quality.  Then instrumentation manufacturers get an exida certificate because exida…

Read More...

Certified to SIL 4 - Cycle Test Failure Data is Dangerous

I got a copy of the IEC 61508 certificate for a solenoid valve today from an engineer who thought something was wrong.  Although the certificate was from a well known certification company, the certificate gave a “Dangerous Failure Rate” of 1.7 FITS (1.7 * 10-9 failures per…

Read More...

  • by Dr. William Goble, CFSE
  • Tuesday, March 08, 2011
  • Certification

Counterfeit Certificate!

I am told that plagiarism is a compliment. Since exida is the leading company for IEC 61508 certifications I suppose it was bound to happen. Well it did. exida got an email from our sales representative in China. He asked why this certificate was not listed on the…

Read More...

  • by Dr. William Goble, CFSE
  • Thursday, May 31, 2012
  • Certification

DANGER, DANGER, DANGER!

Assumed 10 Demands Per Year

During a SIF verification calculation review this week, the engineer pulled out a safety certificate with very low failure rates for a solenoid valve.  Certificate No. V139 2009 C4-4 [1] states that a solenoid valve has a dangerous failure rate of 4.57…

Read More...

Driving with Blinders

Imagine: An automobile that has only one window in the front.  No side windows. The driver can see to steer the auto forward and turn, but cannot see completely from side to side.  What happens when the driver reaches an intersection with no traffic lights? The driver cannot see…

Read More...

  • by Dr. William Goble, CFSE
  • Thursday, September 05, 2013
  • Certification

exida Safety Awards

2013 exida safety Awards

Since the announcement of the 1st Annual exida Safety Awards program a few weeks ago I have received a few questions and a challenge.  The questions from manufacturers mainly focused on how to enter their product and what is the…

Read More...

Field Data Validation with Predictive Analytics

Who cares about field failure data? Why are we even here?

IEC 61511 – Fundamental Concepts

The fundamental concepts from our functional safety standards are the probabilistic performance based design.  Many of you know that this was terribly controversial when this was first proposed. Even to this day, there…

Read More...

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…

Read More...

Functional Safety, Cybersecurity, and Alarm Management in 2013
  • by Dr. William Goble, CFSE
  • Friday, January 10, 2014
  • Certification

Functional Safety, Cybersecurity, and Alarm Management in 2013

2013 was a good year for functional safety progress.  exida Certification issued a record number of new product functional safety certifications in mostly every product category - valves, actuators, solenoid valves, PLCs, fire and gas sensors, process sensors, and components.  The component category is one of the most…

Read More...

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

Read More...

Getting Realistic Failure Rate Data - Part 1

Over the course of several blogs , I will talk about getting realistic failure rate data, where this failure data comes from, and how different methods of failure data analysis compare. I think if you understand this, you will begin to get a very good feel of what it…

Read More...

Getting Realistic Failure Rate Data - Part 2

Over the course of several blogs , I will talk about getting realistic failure rate data, where this failure data comes from, and how different methods of failure data analysis compare. I think if you understand this, you will begin to get a very good feel of what it…

Read More...