BCU 460, BCU 465 · Edition 11.19
124
Project planning information
14 .4 Actuators
If actuators are used, the start gas rate of the burners
must be limited for SIL 3 applications in compliance
with the standard.
14 .5 Parameter chip card
The parameter chip card must be installed in the unit for
the BCU to operate. The parameter chip card contains
the valid parameter settings for the BCU. If a BCU is
replaced, the parameter chip card can be removed from
the old unit and inserted into the new BCU. The BCU
must be disconnected from the electrical power supply
for this purpose. The valid parameters are then adopted
by the new BCU. The old device and the new BCU must
have an identical type code.
14 .6 K-SafetyLink
In furnace control systems, consisting of FCU and
BCU 4, the SafetyLink communications protocol is
used to transfer safety-critical signals between the
FCU and BCU. The data transfer can be enabled using
parameter A081. The FCU must support the function
for communicating via K-SafetyLink.
14 .7 Overload protection
To protect the unit against overload by frequent cycling,
only a specific number of start-up attempts can be car-
ried out by the BCU. The maximum number of start-up
attempts per minute depends on the safety time t
SA
and the ignition time t
Z
.
t
SA
[s]
Device type
Ignition transformer ID number
Max. number
[n/min.]
3
BCU..Q1
34340581
BCU..W1
34340585
6
5
6
10
3
3
BCU..Q2
34340582
BCU..W2
34340586
3
5
2
10
1
3
BCU..Q3
34340583
BCU..W3
34340587
6
5
4
10
2
3
BCU..Q8
34340584
BCU..W8
34340588
4
5
3
10
2
If too many start-up attempts are made,
53
flashes
on the display to indicate a fault.