BCU 480 · Edition 03.16l
24
Function
01
02
03
04
08
00
00
08
05
06
07
Switch on
BCU 480
Pilot burner start-up
with
ϑ
1 signal
Safety interlocks (Limits)
In the event of fault signal:
reset
If parameter P15 = 1:
flame simulation check
Wait until
min. burner pause time t
w
has elapsed
If parameter P15 = 0:
flame simulation check
If no flame detected:
max. 3 start-up attempts
or fault lock-out
Start-up position/standby
Safety time t
SA1
running (P22),
ignition in process,
V1 opens and min.
burner on time t
B
starts to elapse (P20)
In the event of flame failure:
restart or fault lock-out
Operating signal
Pilot burner closes
Flame proving period t
FS1
running (P23)
In the event of flame failure:
fault lock-out
Main burner start-up
with
ϑ
2 signal
Wait until
min. burner pause time t
BP
has elapsed (P21)
If parameter P15 = 0:
flame simulation check
If no flame detected:
max. 3 start-up attempts
or fault lock-out
Safety time t
SA2
running (P22),
V2 opens and
min. burner on time t
B
starts to elapse (P20)
Controlled shut-down
via
ϑ
signal for
pilot and main burners
If min. burner on time t
B
has
elapsed:
operation signalling contact
opens,
V1 and V2 close,
min. burner pause time t
BP
starts to elapse (P21)
In the event of flame failure:
restart or fault lock-out
Operating signal
Main burner closes
Flame proving period
t
FS2
running (P24)
In the event of flame failure:
fault lock-out
3 .4 BCU 480 program sequence
Normal start-up
If an “old” fault is still being signalled after
switching on, it will be necessary to reset this
first.
The safety interlocks (terminal 5) must be
closed and the burner control unit must be
switched on.
The BCU 480 conducts a self-test when in
the start-up position (the burner is switched
off). If it does not determine a malfunction
of the internal electronic circuitry or of the
flame sensors, the burner can be started.
The pilot burner start-up is activated via the
signal input “Start-up signal
ϑ
1” (terminal 4).
Once the start-up signal
ϑ
1 has been applied,
the BCU 480 opens valve V1 and ignites the
burner. The ignition time t
Z
is constant. If a
flame is detected during the safety time t
SA1
,
the flame proving period t
FS1
starts after the
safety time t
SA1
has elapsed.
If the pilot burner has been started success-
fully and its flame has stabilized, the burner
control unit issues the Enable signal for main
burner operation. The operation signalling
contact for the pilot burner (terminals 16/17)
closes.
BCU 480
If the air valve control is used,
the unit offers the following ad-
ditional functions:
In start-up position, the air
valve can be opened for cool-
ing
A
(display
A0
).
Using parameter 31, it can be
determined whether the air
valve can be activated exter-
nally during start-up (display
A1
).
The air valve can be set to open
together with V1 (display
A2
)
via parameter 30.
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