13
NRG 1x-60 - Installation & Operating Manual -
819681-00
Reliability data to EN 61508
Description
Characteristic values
Safety integrity level
SIL 3
Architecture
1oo1
Type of equipment
Type B
Hardware error tolerance
HFT = 0
Overall failure rate for dangerous undetected failures
λ
DU
= < 20 * 10
-9
1/h
Overall failure rate for dangerous detected failures
λ
DD
= < 5000 * 10
-9
1/h
Safe failure fraction
SFF > 99.0 %
Test interval
T1 = 1 year
Probability of failure on demand
PFD < 20 * 10
-5
Diagnostic coverage. Percentage of dangerous failures
detected by a test.
DC > 99.0 %
Mean time to failure
MTTF
D
> 30 a
Diagnostic interval
T2 = 1 hour
Performance level (to ISO 13849)
PL = d
Probability of failure per hour
PFH < 20 * 10
-9
1/h
Ambient temperature as a basis for calculation
Tu = 60 °C
Mean time to repair
MTTR = 0 (no repair)
Fraction of undetected dangerous failures that have a
common cause
beta = 2 %
Fraction of detected dangerous failures that have a com-
mon cause
beta d = 1 %
Fig. 4