Pepperl+Fuchs SMART KCD2-STC-1 - Characteristic Safety Values

Functional Safety KCD2-STC-(Ex)1(.SP), HiC2025(A)
Planning
2020-04
13
3.4 Characteristic Safety Values
The characteristic safety values like PFD, SFF, HFT and T
1
are taken from the
SIL report/FMEDA report. Observe that PFD and T
1
are related to each other.
The function of the devices has to be checked within the proof test interval (T
1
).
Parameters Characteristic values
Assessment type Full assessment
Device type A
Mode of operation Low demand mode or high demand mode
HFT 0
SIL 2
SC 3
Safety function Transfer of the analog signals

s
1
0 FIT

dd
163 FIT

du
40.9 FIT

total (safety function)
1
204 FIT

not part
18.6 FIT
SFF
1
79 %
MTBF
2
276 years
PFH 4.09 x 10
-8
1/h
PFD
avg
for T
proof
= 1 year 1.79 x 10
-4
PFD
avg
for T
proof
= 2 years 3.58 x 10
-4
PFD
avg
for T
proof
= 5 years 8.96 x 10
-4
PTC 100 %
Safety reaction time
Fault reaction time
3
< 20 ms
< 100 ms
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