BCU 580 · Edition 11.15
85
Parameter 75 = 2: MIN. to MAX. capacity; standby in CLOSED
position. The control range while the burner is operating is be-
tween the positions for minimum capacity (S2) and maximum
capacity (S3). The burner is ignited in the position for ignition
capacity (S1). When the burner is switched off, the actuator is
moved to the closed position (S4).
This operating mode can be achieved with an actuator IC 20
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 are protected from the
hot furnace atmosphere as a result of the butterfly valve
being in the closed position (limited by S4). Check whether
the burner can cope without cooling in this situation.
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.
S2: for minimum capacity of the burner.
S3: for maximum capacity of the burner and pre-purge.
S4: for the closed position of the butterfly valve and standby.
0°
90°
S4
S2
S1
S3
Burner control range
CLOSED
Butterfly valve setting range
Control range
Move to ignition position
Ignition pos.
Max. pos.
OPEN
S4
S2
Min.
pos.
Closed
pos.
MIN
MIN
MAX
MAX
PE
L1
N
3 2 1
16
6
7
4
8
12 11
15
13
S3
S4
S11
S10
0°
90°
M
IC 20
PE
S1
S2
90°
➔
0°
0°
➔
90°
S1
Min
Max
Y-
Y+
53
54
55
56
52
1
2
3
46
45
65
66
67
68
49
50
51
17
18
37
38
13
14
15
BCU 580..F1
3,15AT
µC
88
c
c
41
42
24V
DC
5 6
9
11 12
10
7
62 61
Parameters > Air control > Capacity control (bus)
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