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BCU 580 · Edition 11.15l
28
Air control
4 .1 .2 BCU . .F3
BCU 580..C0F3
µC
VAS
VAS 1
VAG
TZI/TGI
VR..L
V1
V2
V4
10
UVS
38
37
18
17
1
2
3
FCU 500
Process control (PCC)
46
49
50
P
HT
A
4
ϑ
2
9
13
14
57
5
41
42
43
ϑ
1
1
2
PLC
The BCU..F3 activates an air valve for purging, cooling
or starting the burner. The required air capacity is re-
leased by the air valve.
As soon as there is a purge signal at terminal 50 of
BCU..F3, the air valve is activated by the output at ter-
minal 10. The protective system (FCU 500) starts the
pre-purge time if there is adequate air flow. After the
elapse of the pre-purge time, the air valve closes for ig-
nition. Once the protective system (terminal 46, safety
interlocks) has issued the enable signal, the burner can
be started by the start-up signal at terminal 1. The gas
valves for the 1
st
stage are opened and the burner is
ignited (on the BCU..C1 after a successful valve check).
After the operating signal has been received from the
burner, the gas valve for the 2
nd
stage opens.
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).