Honeywell Krom Schroder PFU 780 - Page 14

PFU 780 · Edition 02.12l 14
Function
01
02
03
04
08
00
00
08
05
06
07
Switch on PFU 780
Pilot burner start-up
with ϑ1 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 ϑ2 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 signal input “Start-
up signal ϑ2” (terminals 14a/14c) if
required.
Once the start-up signal ϑ2 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 success-
fully and its flame has stabilised,
the operation signalling contact
(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. (Param-
eter 10, “Pilot burner start-up at-
tempts”).
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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