VEGA VEGAPULS 41 4 … 20 mA; HART compact sensor - Manual (Page 64)

64 VEGAPULS 41 – 4 … 20 mA
26620-EN-041227
0 1 2 3 4 5
years
T
proof
= 1 year
T
proof
= 3 years
T
proof
= 5 years
0,00·10 -2
0,20·10 -2
0,40·10 -2
PFD
avg
0,30·10 -2
0,50·10 -2
0,10·10 -2
Supplement
6 Safety-related characteristics
The failure rate of the electronics and the antenna system was determined by an FMEDA (Fail-
ure Mode, Effects and Diagnostics Analysis) acc. to IEC 61508. The number values are based
on an output current tolerance of max. 2 %.
Architecture 1oo1D SIL 2
VEGAPULS 41 Overfill protection Dry run protection Individual level
VEGAPULS 42
VEGAPULS 43
VEGAPULS 44
VEGAPULS 45
HFT 0
SFF > 88%
PFD
avg
1) < 0.10 •10 -2 with T
Proof
= 1 year 2)
< 0.50 •10 -2 with T
Proof
= 5 years
PFH [1/h] 3) < 0.22 •10 -6
Failure reaction time T
Reaction
= 60 sec
Max
Min
1) PFD
avg
this value correlates almost linearly to the operating time. It is only valid for the corresponding
selection circuit.
2) T
Proof
is the interval after which a periodically recurring complete function test (to check the safety function)
must be carried out.
3) PFH is valid for the stated Failure reaction time T
Reaction
of the measuring system. This means that the failure
tolerance time of the complete system must be higher than T
Reaction
.