2
02
2-
06
14
Functional Safety HiC2853R1, HiC2853R4
Planning
HiC2853R4
The characteristic safety values like PFD, PFH, SFF, HFT and T
1
are taken from the
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
Demand mode
Low demand mode or high demand mode
HFT
0
SIL
3
SC
3
Safety function
Signal transfer via electronic
output
Signal transfer via resistive
transistor output
s
187 FIT
146 FIT
dd
0 FIT
0 FIT
du
1.91 FIT
2.99 FIT
total (safety function)
189 FIT
149 FIT
total
439 FIT
440 FIT
SFF
99 %
98 %
MTBF
1
260 years
260 years
PFH
1.91 x 10
-9
1/h
2.99 x 10
-9
1/h
PFD
avg
for T
1
= 1 year
8.37 x 10
-6
1.31 x 10
-5
PFD
avg
for T
1
= 2 years
1.67 x 10
-5
2.62 x 10
-5
PFD
avg
for T
1
= 5 years
4.18 x 10
-5
6.55 x 10
-5
PTC
100 %
Fault reaction time
2
20 ms
Reaction time
3
< 1 s
Table 3.2
1
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.
2
Time between fault detection and fault reaction
3
Step response time
