BCU 480 · Edition 06.07
16
01
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. 4 start-up attempts
or fault lock-out
Start-up position/standby
Safety time t
SA1
running (P22),
ignition in process,
V1 opens and min.
combustion time t
B
starts to elapse (P20)
In the event of flame failure:
restart or fault lock-ou
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. 4 start-up attempts
or fault lock-out
Safety time t
SA2
running (P22),
V2 opens and
min. combustion time t
B
starts to elapse (P20)
Normal shut-down
via
ϑ
signal for
pilot and main burners
If min. combustion 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
BCU 480 program sequence
4 .2
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 cir-
cuitry or of the flame sensors, the burner
can be started. The pilot burner start-up
is activated via the signal input “Start-up
signal V1” (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 tZ is constant. If a flame
is detected during the safety time t
SA1
, the
flame proving period t
FS1
starts after the
safety time tSA1 has elapsed.
If the pilot burner has been started suc-
cessfully and its flame has stabilised, 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 cooling
A
(display
A0
).
Using parameter 31, it can be
determined whether the air valve
can be activated externally dur-
ing start-up (display
A1
).
The air valve can be set to open
together with V1 (display
A2
via
parameter 30.
Function
t
