Other Safety-Related Characteristic Values; Useful Lifetime Of Electric Components - Endress+Hauser Proservo NMS80 Functional Safety Manual

Proservo NMS80/81/83
Other safety-related
characteristic values
Useful lifetime of electric
components
Endress+Hauser
Characteristics as per IEC 61508
Safety function
SIL
HFT
Device type
Operating mode
SFF
MTTR
Recommended time interval for proof-testing T
λ
sd
λ
su
λ
dd
λ
du
1)
λ
tot
2)
PFD for T = 1 year
avg 1
2)
PFD for T = 2 years
avg 1
PFH
1)
MTBF
3)
Diagnostic test interval
4)
Fault reaction time
5)
System reaction time
1) According to Siemens SN29500. This value takes into account failure types relevant to the function of the
electronic components.
2) Valid for ambient temperature up to +40 °C (+104 °F). Where the average temperature when in continuous
use is in the region of +60 °C (+140 °F), a factor of 2.1 should be taken into account.
3) During this time, all diagnostic functions are executed at least once.
4) Time between error detection and error response.
5) Step response time as per DIN EN 61298-2: 274 s
The established failure rates of electrical components apply within the useful lifetime as per
IEC 61508-2:2010 section 7.4.9.5, note 3. In accordance with DIN EN 61508-2:2011 section
7.4.9.5, national footnote N3, appropriate measures taken by the manufacturer and operator can
extend the useful lifetime.
Value
MIN, MAX, Range
SIL 2 (single-channel architecture 1oo1)
SIL 3 (multi-channel architecture, also with homogeneous
redundancy, e.g. 1oo2, 2oo3)
0
B
Low demand mode, high demand mode
98 %
8 h
3 years
1
23 FIT
2 528 FIT
6 205 FIT
185 FIT
8 941 FIT
8.59 -4
1.67 -3
1.85 -7 h -1
28 years
60 min
60 s
In "Expert mode":
User configurable
5