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Functional Safety HiD2024
Planning
3.4
Characteristic Safety Values
Configure the device for the required function via the DIP switches,
see chapter 3.3.
Analog Input Function
Parameters acc. to IEC 61508
Assessment type and documentation
Device type
Mode of operation
HFT
SIL (SC)
Safety function
s
dd
du
total (safety function)
not part
1
SFF
PTC
2
MTBF
PFH
PFD
for T
= 1 year
avg
1
PFD
for T
= 2 years
avg
1
PFD
for T
= 5 years
avg
1
Reaction time
Table 3.2
1
"Not considered" failures are considered 50 % as dangerous undetected and 50 % as "No effect". "No effect"
failures are not influencing the safety functions and are therefore not included in the calculation of the SFF.
2
acc. to SN29500. This value includes failures which are not part of the safety function/MTTR = 8 h. This value
is calculated for one safety function of a device.
Characteristic values
FMEDA report
A
Low Demand Mode or High Demand Mode
0
2
Signal transfer to programmable logic controller
(PLC)
0 FIT
121 FIT
49.9 FIT
171 FIT
59 FIT
70 %
100 %
314 years
-8
4.99 x 10
1/h
-4
2.18 x 10
-4
4.37 x 10
-3
1.03 x 10
< 100 ms
11
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