Systematic Capability is achieved when the equipment used to implement any safety function achieves two goals: the design process has used procedures intended to prevent systematic design errors (fault avoidance) and the design has systematic design control mechanisms such as a diagnostic for incorrect software execution (fault control).  The rigor of the required design process and control measures are a function of a  Safety Integrity Level (SIL). This is evaluated through a detailed assessment of the design and the quality and safety management system for suppliers of sensing, control, and final element devices against the requirements in IEC 61508.  If the design and the design process meet the requirements of IEC 61508, a SIL Capability rating is issued.   The IEC 61508 certificate indicates the systematic capability of a product.  


SIL based on Systematic Capability e.g. SC3 (SIL 3 Capable)

The equipment used to implement any safety function must be designed using procedures intended to prevent systematic design errors.  The rigor of the required procedure is a function of SIL rating.  

Each SIL rating (Levels 1-4) has different requirements to be met if a product is to achieve that SIL rating. For example, SIL 1 Systematic Capability rating, or SC 1, will have X number of requirements to be met, while a product that has a SIL 2 Systematic Capability rating, or SC 2, has to still meet all of the SIL 1 requirements (X), while also meeting the additional SIL 2 requirements. 

Fun facts:

  • The systematic capability of a product is one of the 3 design barriers that must be met for certification. (Link to blog about 3 barriers and cert)
  • Is a limiting factor in SIL. So if your systematic capability meets a SIL 2, it can only go into a SIL 2 SIFor lower (SIL 1 or no SIL). It cannot be a part of SIL 3 SIF.
  • Systematic Capability shows your defense against systematic failures or errors due to quality, or design or processes and procedures.

If you wish to see if a product is certified, and find its systematic capability, you can search on the SAEL.

Related Items

Back to Basics 01 - Functional Safety

Back to Basics 02 - Safety Integrity Level (SIL)

Back to Basics 03 - Safety Instrumented Function (SIF)

Back to Basics 04 - Safety Instrumented System (SIS)

Back to Basics 05 - What is a Safety Function?

Back to Basics 06 – IEC 61508

Back to Basics 07– Safety Lifecycle – IEC 61508

Back to Basics 08 – IEC 61511

Back to Basics 09 – Safety Lifecycle – IEC 61511

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

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

Back to Basics 12 – What is IEC 61508 Certification?

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

Tagged as:     Systematic Capability     Loren Stewart     IEC 61508     exida     certification     back to basics  

Other Blog Posts By Loren Stewart