PFU 780 · Edition 02.12l
25
Parameters
4 .3 Pilot and main burner monitoring
Burner control unit PFU 780 for pilot and main burner
combination of unlimited capacity.
Pilot burner: single-stage-controlled.
Main burner: modulating or stage-controlled.
The burner control unit PFU 780 has separate start-up
signal inputs for the pilot burner (terminal 10e) and the
main burner (terminal 14a). The burner control unit co-
ordinates the program run (the interplay) of both burn-
ers. If required, the main burner can be started once the
pilot burner has reached its operating position. Benefit:
The time for starting up the main burner can be reduced
as low as its safety time. By using two flame amplifiers,
the pilot and main burners can be monitored separately.
The PFU 780 can also be used on indirectly ignited sur-
face burners with end point monitoring.
Three different operating modes are possible:
Permanent pilot burner
t
1
2
ϑ
1
ϑ
2
88
02–04 06–08
04
06–08
04
For applications which require a high system availabil-
ity or where a continuously burning flame is necessary.
The pilot burner is ignited once and remains constantly
in operation. The main burner is controlled separately.
Intermittent pilot burner
t
1
2
ϑ
88
02–04 06–08 00 02–04 06–08 00
Pilot and main burners are controlled with one start-
up signal (terminals 10e and 14a in parallel). The main
burner starts automatically after the operating signal
from the pilot burner has been detected. Operation is
terminated simultaneously for both burners.