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Entries tagged with: IEC61511

10 Years After, Has Anything Been Learned from Deepwater Horizon?

10 Years After, Has Anything Been Learned from Deepwater Horizon?

It’s hard to believe that it’s been 10 years since the Deepwater Horizon incident on April 20th 2010.  Even today, the Gulf Coast is still feeling the effects.  In its latest estimates, BP is looking at a total loss of $65Bn USD, in settlements, fines and compensation.  This latest estimate was published in…

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Are Your Control Systems Really Protected?

Are Your Control Systems Really Protected?

I don’t know whether you’ve noticed recently, but the number of cybersecurity alerts issued by CISA (Cybersecurity and Infrastructure Security Agency) seems to be increasing at an alarming rate.  The latest alert I’ve seen now relates to GPS tracking systems for children.  A device which is supposed to keep…

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Back to Basics 18 – Route 1H

Back to Basics 18 – Route 1H

Route 1H is one of two Architectural constraints options made available in the standards IEC 61508-2 and IEC 61511. Route 1H . Both Route 1H and Route 2H are limitations that impose the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem. 

Route 1H  is…

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Back to Basics 19 – Route 2H

Back to Basics 19 – Route 2H

Route 2H is one of two Architectural constraints options made available in the standards IEC 61508-2 and IEC 61511. Route 1H . Both Route 1H and Route 2H are limitations that impose the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem. 

What exactly is Route 2H

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Back to Basics 20 – Safe Failure Fraction, SFF

Back to Basics 20 – Safe Failure Fraction, SFF

Safe Failure Fraction (SFF) is defined as the ratio of the average rate of safe failures plus dangerous detected failures of the subsystem to the total average failure rate of the subsystem. It is defined for a single channel (no redundancy, 1oo1).

It is a measurement of the likelihood of…

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Back to Basics 21 – The B10 Method

Back to Basics 21 – The B10 Method

The B10 method uses cycle test data to predict failure rates. 

A cycle test is done on a set of products (>20) until 10% of the units under test fail. The number of cycles until failure is called the B10 point.

The B10 number of cycles is converted to a…

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Back to Basics 22 – Cycle Testing

Back to Basics 22 – Cycle Testing

A cycle test is done on a set of products (>20) until 10% of the units under test fail. 

The number of cycles is converted to a time period by knowing the cycles per hour in any particular application. 

A failure rate is calculated by dividing the 10% failure…

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Back to Basics 23 – Stiction

Back to Basics 23 – Stiction

What is Stiction? 

stiction

Stiction is the resistance to the start of motion usually measured as the difference between the external force being applied in order to overcome the static friction and the force to maintain movement between the two contacting or working surfaces.

It can…

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How Secure Is Your Safety Instrumented System (SIS)?

How Secure Is Your Safety Instrumented System (SIS)?

As the cybersecurity threats in the industrial world continue to rise, the automation world continues to grapple with how to address these issues.  As such, the newly released IEC61511-1: 2016 edition has included a new clause to address this (Clause 8.2.4).  In essence, End Users have to carry out…

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Making Use of Leading and Lagging Indicators – Are You Using These for Functional Safety?

Making Use of Leading and Lagging Indicators – Are You Using These for Functional Safety?

Some of you reading this may not be aware or familiar with the terms “leading” and “lagging” indicators, when applied to Functional Safety.  The concept isn’t new but does provide significant benefit when applying this to Functional Safety because, if used correctly, these indicators can help significantly improve performance. …

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Obtaining My CFSE/CFSP Certification: Why Bother?

It’s an interesting question and one I asked myself.  For any engineer and/or professional working in the controls business or process industries where safety-related equipment is required, it is essential (per IEC61511-1 Clause 5.2.2: Organization and Resources) to prove competency to carry out any safety-lifecycle activities.  So what does…

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The Site Safety Challenge – Do You Follow Good Site Practices?

The Site Safety Challenge – Do You Follow Good Site Practices?

The question of whether companies follow good site safety practices is an interesting one. Firstly, what do we mean by good site safety practices?  I think most companies believe they follow good site safety practices but do they really? Are they really measuring and tracking this?

The basis of having good site…

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What is Prior Use Justification?

What is Prior Use Justification?

When it comes to IEC61511 and the selection of equipment for use within Safety Instrumented Systems (SIS) and Safety Instrumented Functions (SIF), there are only two methods that can be used to justify selection: IEC61508 Certified devices for the required SIL or Prior Use Justification.  Just…

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Why Bother With Systematic Issues?

Why Bother With Systematic Issues?

You may be wondering why this question is being asked?  Isn’t it obvious that systematic issues are important and need to be considered?  It may be that some of you reading this blog may not even understand what is meant by systematic issues.  In which case, it may surprise you to know…

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