Vega VEGABAR 54 Operating Instructions Manual page 63

VEGABAR 54 - 4 ... 20 mA/HART
PFD
avg
4
3
2
1
1
Fig. 34: Time-dependent process of PFD
1 PFD = 0
avg
2 PFD after 1 year
avg
3 PFD after 5 years
avg
4 PFD after 10 years
avg
Double channel architecture
If the measuring instrument is used in double channel
architecture, the safety-relevant characteristics of the selected
structure of the measuring chain must be calculated acc. to the
above failure rates (especially for the selected application). A
Common Cause Factor must be taken into account.
Numbers see in the above charts.
11)
Functional safety acc. to IEC 61508-4 (SIL)
5
11)
avg
T
10
Proof
63