BCU 580 · Edition 11.15
116
16 .5 Safety-specific characteristic values
Suitable for Safety Integrity
Level
Up to SIL 3
Diagnostic coverage DC
97.2 %
Type of subsystem
Type B to EN 61508-2:2010
Operating mode
High demand mode pursu-
ant to EN 61508-4:2010
Mean probability of danger-
ous failure PFH
D
11.5 x 10
-9
1/h on BCU 580..F1
11.5 x 10
-9
1/h on BCU 580..F2
14.5 x 10
-9
1/h on BCU 580..F3
Mean time to dangerous
failure MTTF
d
MTTF
d
= 1/PFH
D
Safe failure fraction SFF
99.4 %
Mean probability of dangerous failure PFH
D
of individual
safety functions
5.5 x 10
-9
1/h
5.5 x 10
-9
1/h
Emergency stop with optional input
5.4 x 10
-9
1/h
Air flow monitoring
7.2 x 10
-9
1/h
Air flow monitoring with optional input
7.1 x 10
-9
1/h
6.5 x 10
-9
1/h
Approaching position for ignition capacity with
F1/IC 20
5.6 x 10
-9
1/h
Approaching position for ignition capacity with
F2/RBW
5.9 x 10
-9
1/h
Approaching position for ignition capacity with
F3
5.3 x 10
-9
1/h
SIL 3 is only achieved in conjunction with actuators IC 20 or
RBW if a separate gas valve is used to limit the pilot gas rate,
see page 62 (Burner application), parameter 78 = 3.
Relationship between the Performance Level (PL) and the
Safety Integrity Level (SIL)
PL
SIL
a
–
b
1
c
1
d
2
e
3
Pursuant to EN ISO 13849-1:2006, Table 4, the BCU can be
used up to PL e.
Max. service life under operating conditions:
20 years after date of production.
For a glossary of terms, see page 120 (Glossary).
For further information on SIL/PL, see www.k-sil.de
Technical data