Vega VEGAFLEX 80, Safety Manual

Page: 6 / 20

6
4 Safety-related characteristics
VEGAFLEX 80 series • 4 … 20 mA/HART - two-wire
42960-EN-140924
4 Safety-related characteristics
4.1 Key figures acc. to IEC 61508
Parameter Value
Safety Integrity Level SIL2 in single-channel architecture
SIL3 in multiple channel architecture
3)
Hardware error 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)
Diagnosis 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 56 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
4.2 Figures according to ISO 13849-1
Derived from the safety-related characteristics, the following figures
result according to ISO 13849-1 (machine safety):
6)
Parameter Value
MTTFd 47 years
DC 93 %
Performance Level 1.58 x 10
-7
1/h (corresponds to "d")
4.3 Supplementary information
The failure rates of the instrument were determined by an FMEDA
according to IEC 61508. Basis for the calculations are the component
failure rates according to SN 29500 .
All figures refer to an average ambient temperature of 40 °C (104 °F)
during the operating time. For higher temperatures, the values should
be corrected:
•
Continuous application temperature > 50 °C (122 °F) by factor 1.3
Determination of the
failure rates
3)
Homogeneous redundancy possible
4)
Including errors outside the safety function.
5)
Time during which all internal diagnoses are carried out at least once.
6)
ISO 13849-1 was not part of the certification of the instrument.