SAFETY MANUAL SIL KFD0-RSH-1.4S.PS2
Planning
22
5538
201
1-
04
9
2.4
Characteristic Safety Values
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
Assessment type and
documentation
Full assessment
Fuchs FMEDA report
1
FS-0042EA-20A
Device type
A
Demand mode
Low Demand Mode or High Demand Mode
Safety function
2
ETS
4
DTS
HFT
0
0
SIL
3
3
λ
sd
+
λ
su
139.7 FIT
144.77 FIT
λ
dd
0 FIT
0 FIT
λ
du
7.1 FIT
1.83 FIT
λ
total (safety function)
146.6 FIT
146.6 FIT
SFF
95.2 %
98.7 %
MTBF
3
639 years
560 years
PFH
7.1 x 10
-9
1/h
1.83 x 10
-9
1/h
PFD
avg
for T
1
= 1 year
3.1 x 10
-5
8.01 x 10
-6
T
proof
max.
3 years
12 years
Reaction time
< 20 ms
1
Fuchs documentation number
2
The device can be used in two safety functions, ETS (energized to safe) and DTS (de-energized to safe).
3
acc. to SN29500. This value includes failures which are not part of the safety function/MTTR = 8 h.
4
For ETS in SIL2 applications no proof test has to be carried out, the calculated proof time is higher than the
useful time (T
proof
max. for ETS SIL2 is 32 years).
