Pepperl+Fuchs KFD2-UT2 Series - Page 11

SAFETY MANUAL SIL KFD2-UT2-(EX)*, HID2082
Planning
2011-09
11
HiD2082
The characteristic safety values like PFD/PFH, SFF, HFT and T
proof
are taken from
the SIL report/FMEDA report. Please note, PFD and T
proof
are related to each
other.
The function of the devices has to be checked within the proof test interval
(T
proof
).
Parameters acc. to IEC 61508 Variables
Device type B
Demand mode Low Demand Mode
Safety function Transfer of analog value
HFT 0
SIL 2 (proven-in-use acc. to EN 61511)
λ
s
75 FIT
λ
dd
1
328.6 FIT
λ
du
2
98.1 FIT
λ
no effect
3
312 FIT
λ
total (safety function)
814 FIT
λ
no part
43 FIT
SFF 87.93 %
MTBF
4
133 years
PFD
avg
for T
1
= 1 year 4.30 x 10
-4
T
proof
max. 2 years
1
"Fail high" and "Fail low" failures are considered as dangerous detected failures λ
dd
.
2
Annunciation failure rates that only influence the diagnostic function were marginal and added to the λ
du
.
3
"No effect" failures are not influencing the safety functions and are therefore added to the λ
s
.
4
acc. to SN29500. This value includes failures which are not part of the safety function (MTTR = 8 h).
Ta b l e 2 . 2