BCU 480 · Edition 06.07
27
Pilot and main burner monitoring
5 .3
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 12) and the main burner
(terminal 14). The burner control unit coordinates the pro-
gram 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 surface
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 availability 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 sig-
nal (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 monitoring is required if no distinc-
tion 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.
Parameters
