exida explains Blog

Entries tagged with: Back To Basics

Back to Basics 12 –  What is IEC 61508 Certification?

Back to Basics 12 –  What is IEC 61508 Certification?

IEC 61508 Certification is a Third-Party Validation against the standard’s requirements, comprising of:

  • Detailed Analysis of engineering processes to determine Systematic Capability and Cybersecurity Strength 
  • Detailed Analysis of hardware design / design margins resulting in Random Failure Rate in all failure modes
  • Analysis/Testing to show safe, correct operation and Cybersecurity Susceptibility

To achieve an…

Read More...

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…

    Read More...

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…

Read More...

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…

Read More...

Back to Basics 16 - PFDavg

Back to Basics 16 - PFDavg

PFDavg (the average Probability of Failure on Demand) is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFDavg can be determined as an average probability or maximum probability over a time period. IEC 61508 and IEC…

Read More...

Back to Basics 17 - PFH (Probability of Failure on Demand per Hour)

Back to Basics 17 - PFH (Probability of Failure on Demand per Hour)

PFH (The Probability of Failure on Demand per Hour)  is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFH can be determined as a probability or maximum probability over a time period of an hour. IEC…

Read More...

Back to the Basics 19 – Route 2H

Back to the 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

Read More...

Back to the Basics 20 – Safe Failure Fraction, SFF

Back to the 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…

Read More...