Vega VEGAFLEX 80 series - 4 Safety-Related Characteristics; Characteristics Acc. to IEC 61508; Characteristics Acc. to ISO 13849-1

7
4 Safety-related characteristics
VEGAFLEX 80 series • Two-wire 4 … 20 mA/HART
42960-EN-170410
4 Safety-related characteristics
4.1 Characteristics acc. to IEC 61508
Parameter Value
Safety Integrity Level SIL2 in single-channel architecture
SIL3 in multiple channel architecture
3)
Hardware fault tolerance HFT = 0
Instrument type Type B
Mode Low demand mode, High demand mode
SFF
> 90 %
MTTR 8 h
MTBF = MTTF + MTTR
4)
0.3 x 10
6
h (35 years)
Diagnostic test interval
5)
< 30 min
Failure rates
λ
S
λ
DD
λ
DU
λ
H
λ
L
λ
AD
λ
AU
0 FIT 2154 FIT 158 FIT 9 FIT 60 FIT 32 FIT 19 FIT
PFD
AVG
0.133 x 10
-2
(T1 = 1 year)
PFD
AVG
0.196 x 10
-2
(T1 = 2 years)
PFD
AVG
0.382 x 10
-2
(T1 = 5 years)
PFH
0.158 x 10
-6
1/h
Proof Test Coverag (PTC)
Test type
6)
Remaining failure rate of danger-
ous undetected failures
PTC
Test 1
11 FIT 93 %
Test 2 4 FIT 98 %
4.2 Characteristics acc. to ISO 13849-1
Derived from the safety-related characteristics, the following gures
result according to ISO 13849-1 (safety of machinery):
7)
Parameter Value
MTTFd
47 years
DC 93 %
Performance Level 1.58 x 10
-7
1/h
3)
Homogeneous redundancy possible, because systematic capability SC3.
4)
Including errors outside the safety function.
5)
Time during which all internal diagnoses are carried out at least once.
6)
See section "Proof test".
7)
ISO 13849-1 was not part of the certication of the instrument.