Characteristic Safety Values - Pepperl+Fuchs KCD2-UT2-1 Manual

Functional Safety KCD2-UT2-(Ex)1, HiC2081
Planning
3.4

Characteristic Safety Values

Parameters
Assessment type
Device type
Mode of operation
HFT
SIL (SC)
Safety function
2

s

dd

du

no part
2

total (safety function)
2
SFF
PTC
3
MTBF
1
PFH
4
PFD for T = 1 year
avg 1
4
PFD for T = 2 years
avg 1
5
Reaction time
Table 3.1
1
For the proven-in-use demonstration, sales figures, customer returns and questionnaires filled out by customers were used which
show that no unknown systematic faults are expected. The device is based on a former device that was evaluated for
a proven-in-use statement by exida.com GmbH.
2
For transfer from the FMEDA report the following rules apply: "Annunciation failures" have no direct influence on the safety function
and are therefore counted as "No effect failures". "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.
3
acc. to SN29500. This value includes failures which are not part of the safety function/MTTR = 8 h. The value is calculated for one
safety function of the device.
4
Since the current PTC value is < 100 % and therefore the probability of failure will increase, calculate the PFD value according to the
following formula:
PFD = ( / 2) x (PTC x T
avg du
A service time T of 10 years was assumed for the calculation of PFD
service
5
Time between fault detection and fault reaction
The characteristic safety values like PFD, PFH, SFF, HFT and T
FMEDA report. Observe that PFD and T
The function of the devices has to be checked within the proof test interval (T
12
Characteristic values
FMEDA report with proven-in-use assessment
B
Low demand mode or high demand mode
0
2
Transfer of analog signal
20.1 FIT
293 FIT
69 FIT
27.6 FIT
382 FIT
81,8 %
90 %
162 years
-8
6.93 x 10 1/h
-4
5.79 x 10 1/h
-4
8.52 x 10 1/h
• for temperature input: < 1.5 s
• for potentiometer input: < 3 s
+ (1 – PTC) x T )
1 service
1
.
avg
are taken from the
1
are related to each other.
1
).
1