Honeywell Krom Schroder BCU 580 Technical Information page 94

Parameters
Parameter 75 = 5: IGNITION to MAX. capacity; standby
in CLOSED position; burner quick start.
The control range while the burner is operating is be-
tween the positions for ignition capacity (S1) and maxi-
mum capacity (S3). The burner is ignited in the position
for ignition capacity (S1). Switching cam S2 (reverse di-
rection 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 closed position (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 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 . If pre-purge is active, considerably lower air
capacity than the maximum air capacity will be used
for purging .
IC 20
The position for maximum capacity is achieved by the
controller enable output (terminal 56).
Switching cam settings S1, S2, S3 and S4:
S1: for minimum capacity and ignition capacity of the burner.
S2: for reversing the direction of rotation to approach the position for ignition
capacity. The actuator will move to the position for ignition capacity
without reaching the position for maximum burner capacity.
S3: for maximum capacity of the burner and pre-purge.
BCU 580 · Edition 11.15l
S4: for the closed position of the butterfly valve and standby.
0°
62 61 5 6 7
MIN Burner control range
c
CLOSED Butterfly valve setting range
IGNITION
24V
Move to ignition position
DC
Closed Min.
S1 S2
Ignition Reversing direction of rotation
pos. pos.
88
pos. for quick start
µC
BCU 580..F1
16 15 13 12 11
9 10 11 12
MAX
c
OPEN
Control range MAX
3,15AT
Max. pos.
Y+
Y-
8 7 6 4 3 2 1
PE
S11
S2 S1
S3
S1
Min Max
S2
90°
S3
L1
N
PE
S10
S4
94