Vega VEGAPULS 61 Safety manual - page 12
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.
1
5
10
T
Proof
PFD
avg
1
2
3
4
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