Dangerous failures of the SIS When calculating Probability of Failure of a Safety Instrumented Function (SIF), the most important are the dangerous failures, as we see in the following equations of 1oo1 and 1oo2 architectures.The value Lambda DD is the rate of dangerous detected failures, and Lambda DU corresponds to the undetected ones. We can …
The importance of diagnostics in the SIS The diagnostics in an Safety Instrumented System (SIS) are of crucial importance because they are the key to reduce the rates of undetected dangerous failures and, therefore, to reduce the probability of failure on demand (PFD / PFH) and increase the SIL. We can see it in the …
What is a safety PLC? Let’s try to explain it in a simple way for non-experts. The fundamental difference with a general purpose PLC is summed up in one word “Diagnosis”. In addition, there are differences in terms of internal architecture, software and firmware, and certification for applications where compliance with a certain SIL level …
