PFU 780 · Edition 02.12
14
01
02
03
04
08
00
00
08
05
06
07
Switch on
PFU 780
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
waiting time t
W
has elapsed
If parameter P15 = 0:
Flame simulation check
If no flame detected:
next start-up attempt (P10)
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-out
Operating signal
Pilot burner closes
Flame proving period t
FS1
running (P23)
In the event of flame failure:
restart or 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:
next start-up attempt (P11)
or fault lock-out
Safety time t
SA2
running (P24),
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 (P25)
In the event of flame failure:
restart or fault lock-out
The PFU coordinates the correct program
run for the pilot and main burners. The
main burner can be started via the sig-
nal input “Start-up signal
ϑ
2” (terminals
14a/14c) if required.
Once the start-up signal
ϑ
2 has been
applied (terminals 14a and 14e), the
PFU 780 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 successfully and its flame has
stabilised, the operation signalling con-
tact (terminals 6a/6e) 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. (Parameter 10, “Pilot burner start-
up attempts”).
Function > PFU 780 program sequence
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 ex-
ternally (display
A6
)
via param-
eter 30.
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