BCU 480 · Edition 03.16l
36
Parameters
4 .3 Pilot and main burner monitoring
Automatic burner control unit BCU 480 for pilot and
main burner combination of unlimited capacity.
Pilot burner: single-stage-controlled.
Main burner: modulating or stage-controlled.
The burner control unit BCU 480 has separate start-up
signal inputs for the pilot burner (terminal 4) and the
main burner (terminal 21). The burner control unit coor-
dinates the program run (the interplay) of both burners.
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 BCU 480 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 4 and 21 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.
Interrupted pilot burner
t
1
2
ϑ
1
ϑ
2
88
02–04 06–08
02–04 06–08
The pilot burner is switched off during the main burner
safety time t
SA2
. This type of flame control is required if
no distinction can be made between the flame signals
of the pilot and main burners (e.g. if both burners can
be monitored with a single UV sensor). If the start-up
signal for the pilot burner is applied continually, the
pilot burner restarts immediately after the main burner
has been switched off.