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Functional Safety KCD2-RR2-Ex1(.SP)
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
1
PFD
for T
= 2 years
avg
1
PFD
for T
= 3 years
avg
1
PTC
3
Reaction time
Table 3.1
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 = 8 h.
3
Time between fault detection and fault reaction
The characteristic safety values like PFD, SFF, HFT and T
the 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 resistance values with
an accuracy of 2%.
0 FIT
134 FIT
54.4 FIT
188 FIT
377 FIT
71.1 %
164 years
-8
5.44 x 10
1/h
-4
2.38 x 10
-4
4.77 x 10
-4
7.15 x 10
100 %
< 20 ms
are taken from
1
are related to each other.
1
).
1
11
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