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Functional Safety KCD2-STC-(Ex)1(.SP), HiC2025(A)
Planning
3.4
Characteristic Safety Values
Parameters
Assessment type
Device type
Mode of operation
HFT
SIL
SC
Safety function
1
s
dd
du
1
total (safety function)
not part
1
SFF
2
MTBF
PFH
PFD
for T
= 1 year
avg
proof
PFD
for T
= 2 years
avg
proof
PFD
for T
= 5 years
avg
proof
PTC
Safety reaction time
3
Fault reaction time
Table 3.3
1
"No effect failures" are not influencing the safety function and are therefore not included in SFF and in the failure rates of the safety
function.
2
acc. to SN29500. This value includes failures which are not part of the safety function/MTTR = 24 h.
3
Time between fault occurence and fault reaction
The characteristic safety values like PFD, SFF, HFT and T
SIL report/FMEDA report. Observe that PFD and T
The function of the devices has to be checked within the proof test interval (T
Characteristic values
Full assessment
A
Low demand mode or high demand mode
0
2
3
Transfer of the analog signals
0 FIT
163 FIT
40.9 FIT
204 FIT
18.6 FIT
79 %
276 years
-8
4.09 x 10
1/h
-4
1.79 x 10
-4
3.58 x 10
-4
8.96 x 10
100 %
< 20 ms
< 100 ms
are taken from the
1
are related to each other.
1
).
1
13
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