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Functional Safety K-LB-*.*, F*-LB-I, P-LB-*.*.*
Planning
P-LB-1.B.*, P-LB-2.B.*, P-LB-1.C.*, P-LB-2.C.*, P-LB-2.D.*, P-LB-1.E.* (1oo1 structure)
Parameters
Characteristics
Assessment type
FMEDA report
and documentation
Device type
A
Mode of operation
Low demand mode or high demand mode
1
Safety function
Pass through the signal
HFT
0
2
SIL
2 or 3
1
Signal type
AI
1
Safe state
I
in
Signal line
interrupted
Safety loop fault
< 3.6 mA and
3
detection
> 21 mA can be
detected
+
0 FIT
sd
su
16.1 FIT
dd
5.95 FIT
du
42.1 FIT
no effect
52 FIT
not part
22.05 FIT
total (safety function)
4
MTBF
984 years (1-channel device), 492 years (2-channel device)
PFH
0.59 x 10
PFD
for
2.60 x 10
avg
T
= 1 year
1
Table 3.7
1
The safe state of the surge protection barrier depend on the application.
2
The maximum safety integrity level of the safety loop in which the device might be used depends on the characteristics
of the whole saftey loop and the connected field devices in the application.
3
This fault detection has to be provided by the safety loop architecture
(e. g. NAMUR signal – lead breakage and short circuit detection, current loop > 20 mA).
4
acc. to SN29500. This characteristic includes failures which are not part of the safety function/MTTR = 8 h.
The characteristic safety values like PFD, PFH, SFF, HFT and T
from the FMEDA report. Observe that PFD and T
The function of the devices has to be checked within the proof test interval (T
18
AO
< 3.6 mA
I
< 3.6 mA
out
Signal line
interrupted
No fault detection
since < 3.6 mA is
safe state of the
safety loop
16.1 FIT
0 FIT
5.95 FIT
42.1 FIT
52 FIT
22.05 FIT
-8
1/h
0.59 x 10
-5
2.60 x 10
DI
I
= 0 mA
out
U
= 0 V
out
Signal line
interrupted
SC and LB detection
of the safety loop
8.1 FIT
8.0 FIT
5.95 FIT
42.1 FIT
52 FIT
22.05 FIT
-8
-8
1/h
0.59 x 10
1/h
-5
-5
2.60 x 10
are related to each other.
1
DO
I
= 0 mA
out
U
= 0 V
out
Signal line
interrupted
No fault detection
16.1 FIT
0 FIT
5.95 FIT
42.1 FIT
52 FIT
22.05 FIT
-8
0.59 x 10
1/h
-5
2.60 x 10
are taken
1
).
1
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