Pepperl+Fuchs KFD2-SR3-2.2S, Руководство пользователя, Страница: 12 / 20

20
16-03
12
Functional Safety KFD2-SR3-(Ex)2.2S
Planning
3.4 Characteristic Safety Values
The characteristic safety values like PFD, PFH, SFF, HFT and T
1
are taken from
the 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 acc. to IEC 61508 Characteristic values
Assessment type and documentation Full assessment
Device type A
Mode of operation Low demand mode or high demand mode
HFT 0
SIL (SC) 2
Safety function Normal/inverted operation

s
1
145 FIT

dd
4.1 FIT

du
73 FIT

total (safety function)
1
1
"No effect failures" and "Annunciation failures" are not influencing the safety function and are therefore not
included in the SFF and the safety values of the safety function.
222 FIT

not part
77 FIT
SFF
1
67 %
MTBF
2
2
acc. to SN29500. This value includes failures which are not part of the safety function/MTTR = 24 h. The
value is calculated for one safety function of the device.
270 years
PFH 7.26 x 10
-8
1/h
PFD
avg
for T
1
= 1 year 3.18 x 10
-4
PFD
avg
for T
1
= 2 years 6.36 x 10
-4
PFD
avg
for T
1
= 5 years 1.59 x 10
-3
PTC 100 %
Table 3.2