BCU 580 · Edition 11.15
75
Operating mode 27
During the controller enable procedure, the actuator IC 40
can be adjusted infinitely between the positions for maximum
and minimum capacity using its analogue input (terminals 18
and 19). There is no timeout active in this case.
t [s]
t [s]
t1
t2
t3
t4
t5
t6
0–20
mA
DI 1
DI 2
Purge
Closed
Ignition
BCU
IC 40 (operating mode 27)
Signal at
terminal
Position
Butterfly valve position
55
53
OFF
OFF
Closed
Closed
ON
OFF
Ignition
Minimum/Ignition capacity
ON
ON
0 – 20 mA
Any position between mini-
mum and maximum capacity
OFF
ON
Purge
Maximum capacity
Fault
In the event of a fault, there will be no signal at terminals
53 and 55 so that the actuator moves to the closed position.
When approaching the closed position, no timeout of 255 s
is active since no feedback input is checked. This may result
in a situation where the program is continued in the case of
a request for the closed position, without the butterfly valve
being closed. The outputs at terminals 56 (controller enable)
and 54 (closed position) on the BCU are non-functional and
are not activated.
Manual mode
In Manual mode, no external controller is enabled. The actua-
tor can be moved to the positions for maximum capacity or
ignition capacity by the user. 3-point step operation is not pos-
sible. No timeout is active when approaching these positions.
Parameters > Air control > Capacity control
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