How Does IEC 61508 Apply To Low Complexity E/E/PE Safety-Related Systems?

If the standard is used for low complexity E/E/PE safety-related systems, where dependable field experience exists which provides the necessary confidence that the required safety integrity can be achieved, certain of the requirements specified in the standard may be unnecessary and exemption from compliance with such requirements is acceptable provided this is justified (4.2 of IEC 61508-1).

The standard does not state which requirements this applies to, which is for the user of the standard to decide and justify. Note, however, that the conditions in which this relaxation applies are very restrictive.

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