BCU 580 · Edition 11.15l 90
Parameters
10.6.9 Capacity control (bus)
Parameter 75
Controlling the burner capacity using the fieldbus is
only possible with bus module BCM 500 connected
and enabled (P80 = 1 or 2).
The output at terminal 56 has a different function.
Parameter 75 = 0: Off. No capacity control possible us-
ing the fieldbus.
Parameter 75 = 1: MIN. to MAX. capacity; standby in
position for MIN. capacity. The control range while
the burner is operating is between the positions for
minimum capacity (S4) and maximum capacity (S3).
The burner is ignited in the position for ignition capac-
ity (S1). When the burner is switched off, the actuator is
moved to the position for minimum capacity (S4).
This operating mode can be achieved with an actuator
IC 20, RBW or alternatively with a comparable three-
point step actuator.
If the air supply is stopped on a heated furnace with
the burner switched off, the controls may be dam-
aged by the hot furnace atmosphere as a result of the
lowest possible position of the butterfly valve, limited
by S4.
IC 20
Switching cam setting for ignition capacity, minimum and maximum capacity
as well as pre-purge and standby:
S1: for ignition capacity of the burner.
S3: for maximum capacity of the burner and pre-purge.
S4: for minimum capacity of the burner and standby.
0° 90°
S4
S1 S3
Burner control range
Butterfly valve setting range
Control range
Move to ignition position
Ignition pos.
Min.
pos.
Closed
pos.
Max. pos.
MIN
MIN
MIN
MAX
MAX
MAX
PE
L1
N
3 2 116 67 4812 1115 13
S3 S4
S11
S10
0°
90°
M
IC 20
PE
S1S2
90°➔0°
0°➔90°
S1
Min Max
Y-
Y+
53 54 55 56
52
65 66 67 68
49 50 51
17 18 37 38
13 14 15
BCU 580..F1
µC
88
c
c
41 42
24V
DC
5 6 9 11 1210762 61
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