Hello, I'm trying to run pfd assessments on safety functions using the Simatic Safety System (please see attached). However, it was not very clear what proof test intervals are associated with the claimed pfd for the Simatic Safety System (CPU, I/O's etc). The only metric mentioned was the mission time and I had to find out via another separate document that Siemens systems are designed with Working Life = Proof Test Interval. However, it still was not clear because some of the items like 6ES7136-6RA00-0BF0, show a mission life of 20 years and at the same time specific function test intervals (proof test?) of 1 year or 1 month depending on SIL requirement.

I'm just looking for clarification on what proof test intervals are associated to each claimed pfd.

Thanks in advance

Ghassan

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Split from SIL level.

Hello Ghassan;

I hope the information you are looking for can be found in the following document, or at least that the equations provided will allow you to calculate the proof test instervals for your project:

https://support.industry.siemens.com/cs/document/62153513/what-are-the-requirements-for-the-proof-test-interval-?dti=0&lc=en-WW

Hope this helps,

Daniel Chartier

Hello Daniel, thanks for your reply, but no it didn't help. I've seen this document before and that's where I got the assumption that the proof test interval is related to the mission life; my original question is still not answered as far as I could tell. Thanks for trying, appreciate it.

Ghassan