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IC 40 · Edition 07.18
8
Application
1 .1 .4 Staged control with pre-purge
The central control system starts the pre-purge. Input
DI 2 is activated via the air valve output of the BCU and
the butterfly valve BVA is set to the pre-purge position.
In the event of a temperature demand, the burner con-
trol unit BCU activates input DI 1 via the valve output
V1 and moves the butterfly valve to the ignition position
(precondition: the IC 40 must have reached the ignition
position on the instant of ignition). The burner starts.
To activate the high-fire rate, DI 2 is actuated via the air
valve output on terminal 26 of the BCU.
The butterfly valve moves cyclically between the high-
fire rate position and the low-fire rate position (see
Operating mode 11, 2-stage operation with two digital
inputs).
DI 1/V1 DI 2/air valve
IC 4 position
Valve position
Off
Off
closed
Closed
On
Off
low
Ignition position/low-fire rate
On
On
middle
High-fire rate
Off
On
high
Pre-purge
BVA
VAG
BCU 460..L
IC 40
12
26
L1, N, PE
9
4
7
DI 1
DI 2
5
3
BIO/
BIC
µC
V1
M
4
18
19
16
17
22
P
23
A
P
VAG
VAS
PLC