Pepperl+Fuchs KFD2-CD-1.32 Series - Characteristic Safety Values

2018-11
12
Functional Safety KFD2-CD-(Ex)1.32-**
Planning
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 and
documentation
Full assessment
Device type A (only hardware)
Mode of operation Low demand mode, high demand mode or continuous mode
Safety function Transfer of analog signals from
the input to the output with a
deviation of less than 2 %, current
driver function.
Transfer of analog signals from the
to the output with a deviation of less
than 2 %, voltage driver function.
HFT 0
SIL (hardware) 2

sd
+ 
su
1
1
"No effect failures" and "No part failures" are not influencing the safety function and are therefore not included in the SFF calculation
of the safety function.
0 FIT 0 FIT

dd
92 FIT 97.1 FIT

du
47.6 FIT 48.3 FIT

total (safety function)
139.6 FIT 145.4 FIT

no effect
1
110 FIT 102 FIT

fail high
2
2
May be used if too high output values are detected by the field device, see chapter 3.2.
24.8 FIT 28.2 FIT
SFF
1
65.90 % 66.81 %
PTC 100 % 100 %
MTBF
3
3
acc. to SN29500. This value is valid for the safety function of the device/MTTR = 8 h.
278 years 265 years
PFH 4.76 x 10
-8
1/h 4.83 x 10
-8
1/h
PFD
avg
for T
1
= 1 years 2.08 x 10
-4
2.11 x 10
-4
PFD
avg
for T
1
= 3 years 6.25 x 10
-4
6.34 x 10
-4
PFD
avg
for T
1
= 5 years 1.04 x 10
-3
1.06 x 10
-3
Reaction time
4
4
Time between fault detection and fault reaction
< 50 ms
Table 3.2