BCU 370 · Edition 01.19
27
PE
r1
s
r
BCU 370..I1
V1
F1
F3
230V~
l
v1 v2
s1
v3
c
c
max. 1 A,
253 V
max. 1 A,
253 V
V1
C
S1
S
L
A
Z
M V2 V3
R
C
3
1 2
4 5 6 7 8 9 10 11 12 13 14 15 16
19
17 18
20 21 22 23 24 25 26 27 28 29 30 31 32
L1 (L1)
N (L2)
PE
N
V2
V3
DL
DG
min
DG
max
M
3PS
ϑ
p
p
p
I
Z
90°
➔
0
0
➔
90°
Function
3 .2 .5 Controlled air flow
The controlled air flow function is enabled when the
controlled air flow input, terminal 22 or via Status and
fault messages for PROFIBUS DP, is activated. Cold air
is fed to the combustion chamber, e.g. for cooling.
Following the air pressure switch DL “no flow” state
check, the BCU 370 starts the fan and opens the but-
terfly valve to the Open position. The pressure switch
for air DL monitors the air pressure.
If the start-up signal (
ϑ
) is applied during controlled air
flow, the burner is started. If the elapsed controlled air
flow time is at least as long as the set pre-purge time,
the burner starts immediately after the Ignition position
has been reached. If it is shorter, the total air volume is
supplied until the end of the pre-purge time.
Activation of the controlled air flow input is not required
for normal burner start.
Activation of the controlled air flow function during
burner operation will be ignored.