BCU 480 · Edition 06.07
17
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01
02
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08
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00
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06
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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
The BCU coordinates the correct pro-
gram run for the pilot and main burn-
ers. The main burner can be started via
the signal input “Start-up signal
ϑ
2” (ter-
minal 21) if required. Once the start-up
signal
ϑ
2 has been applied (terminal 21),
the BCU 480 opens valve V2. The main
burner is ignited by the pilot burner. If a
flame is detected during the safety time
t
SA2
, the flame proving period t
FS2
starts
after the safety time t
SA2
has elapsed. If
the main burner has been started suc-
cessfully and its flame has stabilised, the
operation signalling contact (terminals
28/29) closes.
Start-up of the pilot burner without
flame signal
If no flame is detected during the safety
time t
SA1
, either a fault lock-out occurs
or up to three further start-up attempts
occur. The required functions and, if
applicable, the number of start-up at-
tempts must be specified when order-
ing. (Parameter 10, “Pilot burner start-up
attempts”).
The air valve can be set to open
together with V1 (display
A4
) via
parameter 30.
The air valve can be set to open
together with V1 (display
A3
) via
parameter 30.
The air valve can be set to open
together with V1 (display
A5
) via
parameter 30.
The air valve can be set to open
with V2 or to be activated exter-
nally (display
A6
) via parameter
30.
Function > BCU 480 program sequence
t
