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6
4
Safety-related characteristics
4.1
Characteristics acc. to IEC 61508
Parameter
Safety Integrity Level
Hardware fault tolerance
Instrument type
Mode
SFF
MTTR
MTBF = MTTF + MTTR
Diagnostic test interval
5)
Fault reaction time
6)
Failure rates
λ
λ
S
DD
329 FIT
186 FIT
PFD
AVG
PFD
AVG
PFD
AVG
PFH
Proof Test Coverag (PTC)
Remaining failure rate of danger-
Test type
7)
Test 1
Test 2
4.2
Characteristics acc. to ISO 13849-1
Derived from the safety-related characteristics, the following figures
result according to ISO 13849-1 machine safety):
Parameter
MTTFd
DC
Homogeneous redundancy possible.
3)
Including errors outside the safety function.
4)
Time during which all internal diagnoses are carried out at least once.
5)
Time between the occurrence of the event and the output of a fault signal.
6)
See section "Proof test".
7)
ISO 13849-1 was not part of the certification of the instrument.
8)
SITRANS LVL200H - Safety Manual
Value
SIL2 in single-channel architecture
SIL3 in multiple channel architecture
HFT = 0
Type B
Low demand mode, High demand mode
> 90 %
8 h
1.01 x 10
h (116 years)
4)
6
< 120 s
< 2 s
λ
λ
DU
H
36 FIT
0 FIT
0.030 x 10
-2
0.044 x 10
-2
0.087 x 10
-2
0.036 x 10
1/h
-6
ous undetected failures
11 FIT
2 FIT
Value
489 years
85 %
3)
λ
λ
L
AD
0 FIT
11 FIT
(T1 = 1 year)
(T1 = 2 years)
(T1 = 5 years)
PTC
68 %
96 %
8)
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