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Entries tagged with: IEC 61508

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 Dave Butler, CFSE
  • Tuesday, June 25, 2013
  • Software

Allocation vs. Derivation

Please see the first entry of the Requirements Management blog series here.

The concepts of allocation and derivation are sometimes misunderstood when it comes to requirements management.  This can lead to confusion and even to safety problems.  The process of derivation involves the writing of a new requirement, …

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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…

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Are You Building a Safer World?

Are You Building a Safer World?

Every man takes care that his neighbor shall not cheat him. But a day comes when he begins to care that he does not cheat his neighbor. Then all goes well.”  - Ralph Waldo Emerson

I like to think about functional safety in a similar way.  We all want…

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  • by John Yozallinas, CFSE
  • Thursday, August 16, 2012
  • Certification

Are You Going for Gold in Safety?

Olympic athletes don’t wake up one day and decide to compete in the Olympics.  They don’t arrive at the games by chance or coincidence.  Their journey starts long before the games begin. They are often influenced and inspired by watching others or by their own interests.  They may begin…

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Back to Basics 01 - Functional Safety

Back to Basics 01 - Functional Safety

In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety.  We'll start with some more general terms and descriptions and make our way to more advanced material.

1. Functional Safety

Functional safety means the…

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Back to Basics 02 - Safety Integrity Level (SIL)

Back to Basics 02 - Safety Integrity Level (SIL)

In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety.  We'll start with some more general terms and descriptions and make our way to more advanced material.

2. Safety Integrity Level (SIL)

Safety…
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Back to Basics 03 - Safety Instrumented Function (SIF)

Back to Basics 03 - Safety Instrumented Function (SIF)

In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety.  We'll start with some more general terms and descriptions and make our way to more advanced material.

3. SIF

SIF – Safety Instrumented Function…

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Back to Basics 07– Safety Lifecycle – IEC 61508

Back to Basics 07– Safety Lifecycle – IEC 61508

The IEC 61508 standard recommends the use of a functional safety lifecycle. Any safety lifecycle can be used, but the standard does lay out a nominal 16-step process which can be divided into three main classifications as an example. 

The Analysis phase of the lifecycle deals with gathering background…

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Back to Basics 08 – IEC 61511

Back to Basics 08 – IEC 61511

IEC 61511: 2016 Process Industry Sector

IEC 61511 is a technical standard that sets out practices in the engineering of systems that ensure the safety of an industrial process through the use of instrumentation. It entails requirements for users of process control and instrumentation for component / element or sub-system safety.…

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Back to Basics 10 – How Does a Product Get a SIL?

Back to Basics 10 – How Does a Product Get a SIL?

IEC 61508 functional safety standard indicates Safety Integrity Levels (SIL) needs to be evaluated by three design barriers:

  • The Systematic Capability Rating
  • The Architectural Constraints for the Element
  • The Probability of Failure for the Product

What Makes a SIL?

Systematic Capability is achieved when the equipment…

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Back to Basics 11 – How is SIL Used by an End User?

Back to Basics 11 – How is SIL Used by an End User?

Back to Basics 13 - How Do I Start IEC 61508 Certification?

Back to Basics 13 - How Do I Start IEC 61508 Certification?

Do you want to know more about IEC 61508 certification, but you’re not sure if you are ready to jump in? Don’t worry, we will make this process as painless as possible.

Here is what to expect:

  1. Introduce Scope
  2. Kickoff Meeting
  3. Perform FMEDA on Product
  4. Creation of…

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Back to Basics 14 - Systematic Capability

Back to Basics 14 - Systematic Capability

Systematic Capability is achieved when the equipment used to implement any safety function is designed using procedures intended to prevent systematic design errors.  The rigor of the required procedure is a function of a Safety Integrity Level (SIL). This is evaluated through an assessment of the quality management system…

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Back to Basics 15 - Architectural Constraints

Back to Basics 15 - Architectural Constraints

Architectural constraints are limitations that are imposed on the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem. Architectural constraints are specified (in) according to the required of the subsystem, type of components used, and of the subsystem’s components. (Type A components are simple devices…

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Building a Foundation for an IEC 61508 Development Process

Building a Foundation for an IEC 61508 Development Process

There are organizations that are small enough to follow an informal or even undocumented process and still produce a product of sufficient quality to meet market needs.  When these organizations attempt to develop a safety product, they inevitably fall short of meeting the requirements of IEC 61508.  A formalized…

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

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

  • 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…

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Certification and the Environmental Test
  • by John Yozallinas, CFSE
  • Tuesday, August 18, 2015
  • Certification

Certification and the Environmental Test

Functional Safety Assessments (FSA) focus on the relevant functional safety standards that are to be applied to a product in the appropriate industry.  These are standards such as IEC 61511 in the process automation industry, or ISO 26262 in the automotive industry.  And IEC 61508 is like an umbrella…

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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…

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