Honeywell Krom Schroder BCU 580, Technical Information, Page: 123 / 131

BCU 580 · Edition 11.15l 123
Technical data
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 pursuant to EN
61508-4:2010
Mean probability of dangerous 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
Valve proving system 5.5 x 10 -9 1/h
Safety interlocks 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
Flame control 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 65 (Burner application), pa-
rameter 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 127 (Glossary).
For further information on SIL/PL, see www.k-sil.de