Honeywell Krom Schroder BCU 580 Technical Information page 93

Parameters
Parameter 75 = 4: MIN. to MAX. capacity; standby in
position for MIN. capacity; burner quick start.
The control range while the burner is operating is be-
tween the positions for minimum capacity (S4) and
maximum capacity (S3). The burner is ignited in the
position for ignition capacity (S1). Switching cam S2
(reverse direction of rotation) ensures that the position
for ignition capacity is approached without pre-purging
first (quick start). When the burner is switched off, the
actuator is moved to the position for minimum capac-
ity (S4).
This operating mode can be achieved with an actua-
tor 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 may be dam-
aged by the hot furnace atmosphere as a result of the
lowest possible position of the butterfly valve, limited
by S4 . If pre-purge is active, considerably lower air
capacity than the maximum air capacity will be used
for purging .
IC 20
Switching cam setting for ignition capacity, minimum and maximum capacity
and reverse direction of rotation to approach the position for ignition capacity:
S1: for ignition capacity of the burner.
S2: for reversing the direction of rotation to approach the position for ignition
capacity.
S3: for maximum capacity of the burner and pre-purge.
S4: for the closed position of the butterfly valve and standby.
BCU 580 · Edition 11.15l
0°
MIN 62 61 5 6 7 Burner control range 9
c
c
MIN Butterfly valve setting range
S4
MIN
24V
Move to ignition position
DC
Closed Min.
S1 S2
pos. pos.
Ignition Reversing direction of rotation
pos. 88 for quick start
µC
BCU 580..F1
16 15 13 12 11
S1
Min
S2
▼
10 11 12 MAX
OPEN
Control range MAX
3,15AT
Max. pos.
Y+
Y-
8 7 6 4 3 2 1
PE
S11
S2 S1
S3
Max
90°
S3
L1
N
PE
S10
S4
93