Vega VEGAFLEX 81 Safety Manual - page 6
6
4Safety-relatedcharacteristics
VEGAFLEX 80 series • 4 … 20 mA/HART - two-wire
42960-EN-140924
4 Safety-related characteristics
4.1 Keyfiguresacc.toIEC61508
Parameter
Value
SafetyIntegrityLevel
SIL2insingle-channelarchitecture
SIL3 in multiple channel architecture
3)
Hardwareerrortolerance
HFT = 0
Instrument type
Type B
Mode
Lowdemandmode,Highdemandmode
SFF
>90%
MTTR
8 h
MTBF=MTTF+MTTR
4)
0.3x10
6
h(35years)
Diagnosistestinterval
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
0.133x10
-2
(T1=1year)
PFD
AVG
0.196x10
-2
(T1=2years)
PFD
AVG
0.382x10
-2
(T1=5years)
PFH
0.158x10
-6
1/h
4.2 Figures according to ISO 13849-1
Derivedfromthesafety-relatedcharacteristics,thefollowingfigures
resultaccordingtoISO13849-1(machinesafety):
6)
Parameter
Value
MTTFd
47 years
DC
93%
Performance Level
1.58x10
-7
1/h(correspondsto"d")
4.3 Supplementary information
ThefailureratesoftheinstrumentweredeterminedbyanFMEDA
accordingtoIEC61508.Basisforthecalculationsarethecomponent
failureratesaccordingtoSN 29500.
Allfiguresrefertoanaverageambienttemperatureof40°C(104°F)
duringtheoperatingtime.Forhighertemperatures,thevaluesshould
becorrected:
•
Continuousapplicationtemperature>50°C(122°F)byfactor1.3
Determination of the
failure rates
3)
Homogeneousredundancypossible
4)
Includingerrorsoutsidethesafetyfunction.
5)
Timeduringwhichallinternaldiagnosesarecarriedoutatleastonce.
6)
ISO13849-1wasnotpartofthecertificationoftheinstrument.