24d (edited) • Functional Safety Question ❓
Hardware Fault Tolerance (HFT)
Hi all,
Question on HFT ... As an example, If during design your SIF is required to have a minimum HFT of 1 (i.e. the system can withstand one dangerous failure to one channel) is 1oo2 still considered HFT = 1?
Although I always believed this to be the case, I have seen an argument to say that this is actually not true as if one channel fails, you cannot continue to perform the safety function with one dangerous failure present, i.e. it then becomes a 1oo1 when a single fault occurs .... unless you have good enough Diagnostic Coverage (DC%) in each channel to detect the fault early; then this can be classed as 1oo2D (with diagnostics) and still claim HFT =1.
Just wondering what other peoples thoughts are on this and if the above statement is correct? and if it is correct, then what kind of DC% would you be looking for to qualify your voted system as 1oo2D?
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Hardware Fault Tolerance (HFT)
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