Functional Safety M-LB-(Ex-)5000-System
Planning
201
8-03
13
3.4
Characteristic Safety Values
1oo1 Structure
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
Full assessment
Device type
A
Mode of operation
Low demand mode or high demand mode
Safety function
1
1
The safe state of the surge protection barrier depend on the application.
Pass through the signal
HFT
0
SIL
2
2
The maximum safety integrity level of the safety loop in which the device might be used depends on the performance values of the
whole safety loop or the elements of the safety loop. See chapter 7.
3
Devices
M-LB-(Ex-)51**, M-LB-(Ex-)52**, M-LB-(Ex-)50**(.SP)
2-wire
2-wire (TC)
3-wire
4-wire
s
16.8 FIT
0 FIT
14.9 FIT
19.8 FIT
du
1.1 FIT
17.8 FIT
8.4 FIT
15.2 FIT
dd
0 FIT
0 FIT
0 FIT
0 FIT
no effect
17.3 FIT
17.3 FIT
46 FIT
57.3 FIT
total (safety function)
17.8 FIT
17.8 FIT
23.3 FIT
35 FIT
MTBF
3
3
acc. to SN29500. This value includes failures which are not part of the safety function/MTTR = 24 h.
3247 years
3252 years
1646 years
1236 years
PFH
1.05 x 10
-9
1/h
1.78 x 10
-8
1/h
8.44 x 10
-9
1/h
1.52 x 10
-8
1/h
PFD
avg
for T
1
= 1 year
4.60 x 10
-6
1/h
1.69 x 10
-4
1/h
9.35 x 10
-5
1/h
1.44 x 10
-4
1/h
PFD
avg
for T
1
= 2 years
9.20 x 10
-6
1/h
3.38 x 10
-4
1/h
1.87 x 10
-4
1/h
2.89 x 10
-4
1/h
PFD
avg
for T
1
= 5 years
2.30 x 10
-5
1/h
8.46 x 10
-4
1/h
4.68 x 10
-4
1/h
7.22 x 10
-4
1/h
PFD
avg
for T
1
= 10 years
4.60 x 10
-5
1/h
1.69 x 10
-3
1/h
9.35 x 10
-4
1/h
1.44 x 10
-3
1/h
PTC
100 %
87 %
83 %
87 %
Reaction time
4
4
Time between fault detection and fault reaction
< 1 ms
Table 3.2
