18
When the TC control thermostat and minimum temperature thermostat close, the control box which carries out
a check up of the various internal electrical circuits is activated; therefore, the burner motor and the ignition
transformer start up. The pre-ventilation and pre-ignition phases begin (t1 and t3); the VE1 solenoid valve is
energised, and fuel arrives at the first flame nozzle. The pre-ventilation phase ends and the safety time (t2) lapse
starts. During the safety time lapse, a regular flame must form. The spark between the tips of the electrodes
continues and therefore the post ignition phase (t3n) is established. Then, 5 seconds after VE1 has been energised,
the control box is triggered by the air servo control to open the second flame solenoid valve, thus ending the
burner start up program. If for any reason the flame does not form, the control box shuts down in the lock-out
position. The red LR lamp on the control board signals this situation (see page 17) and remains permanently lit.
As soon as the control box shuts down, the burner motor stops along with the ignition transformer. At this point,
the scavenging solenoid valve is not energised interrupting the flow of fuel to the boiler.
To reset the burner, act on the PS reset button (see page 17)
OPERATING CYCLE
MB
TR
VE1
VE2
FR
t1
t3
t 2
t3n
t 4
TC
1
3
6
4
5
11
12
LOA 44.../LMO 44
LEGEND
TC
Boiler thermostat
MB
Burner motor
VE1
1
°
flame solenoid valve
VE2
2
°
flame solenoid valve
FR
Photocell
TR
Ignition transformer
t1
Pre-ventilation time
~ 25 s
t3
Pre-ignition time
~ 25 s
t2
Safety time
max. 5 s
t3n
Post ignition time
(~ 2 s* LOA 44)(~ 5 s* LMO 44)
t4
Time interval between the VE1 and VE2 commands
~ 5 s*
-
Lock-out due to no flame
>1 s
* Active as soon as flame is present.
necessary input signals
output signals
Содержание PG 45
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