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Function (cont´d)
Control sequence
following a controlled
shutdown
Control sequence
following lockout reset
of the burner control
Program indicator
Reading the program
indicator
10/19
Building Technologies
Controlled shutdown takes place as soon as one of the control or monitoring devices in
the control loop between terminals 8 and 9 opens its contacts.
As a result, the fuel valves are immediately shut and the sequence switch is restarted
to program postpurging, if scheduled.
On completion of the postpurge time, the sequence switch has reached its start position
again, which is maintained until the next switch-on command is given.
During the postpurge time, flame supervision is started again. Hence, any flame signal
that occurs during that period of time will lead to lockout.
After pressing the built-in or remote lockout reset button, the sequence switch will
return to its start position.
In that case, the only burner plant component that is switched on is the fan motor
connected to terminal 17.
Since in normal circumstances the control thermostat or pressurestat continues to call
for heat, the burner control immediately triggers a new start when the start position is
reached.
The program indicator continuously indicates the progress of the startup sequence.
The letters on the indicator disk correspond to those in the adjacent sequence switch
diagram. The numbers give the remaining prepurge time.
In the event of lockout, both sequence switch and program indicator stop, showing the
phase of operation during which lockout occurred.
¬ Prepurge time lasts another 35
seconds
30
40
Valve 2 at terminal 7 opens ®
F
E
D
CC1N7461en
21.08.2018
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