PFH <0.358x10
-6
/h
The chronological sequence of PFD
avg
is nearly linear to the
operating time over a period up to 10 years. The above values
apply only to the T
Proof
interval after which a recurring function
test must be carried out.
Fig. 1: Chronological sequence of PFD
avg
(figures see above charts)
1 PFD
avg
= 0
2 PFD
avg
after 1 year
3 PFD
avg
after 5 years
4 PFD
avg
after 10 years
Multiple channel architecture
If the measuring system is used in a multiple channel
architecture, the safety-relevant characteristics of the selected
structure of the meas. chain must be calculated specifically for
the selected application according to the above failure rates.
A suitable Common Cause Factor must be taken into account.
The measuring system must only be used in a diversitary
redundant architecture!
Time-dependent process of
PFD
avg
Specific characteristics
12 VEGAPULS series 60 - 4 … 20 mA/HART
Functional safety
31338-EN-070510
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