Honeywell Krom Schroder BCU 580 Technical Information page 27

Air control
Modulating control
Parameter 48 = 3
After the operating signal has been received from the
burner and after expiry of the delay time for the control-
ler enable signal (parameter 44), the BCU issues the
controller enable signal via the output at terminal 56.
Access to the control element is thus transferred to
an external temperature controller (3-point step). The
temperature controller controls the burner capacity (air
volume) on the basis of the required temperature. De-
pending on the wiring of the temperature controller, the
actuator may be adjusted between maximum capacity
and ignition capacity or minimum capacity.
Depending on parameter 40, an actuator IC 20, IC 40,
IC 50 or an actuator with an RBW interface can be ac-
tuated via the outputs for capacity control. Detailed
information about parameter 40, see from page 75
(Capacity control).
Staged control
P48 = 0, 1 or 2
Depending on parameters 48 and 49, the control
element may be activated either by the program or
externally via the input at terminal 2, see also from
page 86 (Air actuator control).
BCU 580 · Edition 11.15l 27