baltur GI1000 Lx ME Mode D'emploi page 28

DIFFERENTIAL AIR PRESSURE SWITCH WORKING
The air pressure switch works to ensure safe working of the
equipment (locking it off) if the air pressure is not at the expected
level. The pressure switch must therefore by adjusted to act by
closing the NO contact (normally open) when the air pressure in
the burner reaches a certain level. The connection circuit for the
pressure switch is self-controlling and so the NC contact (normally
closed), which should be closed when idle (with the fan off and
therefore no air pressure in the burner), must actually be in this
state, if not the control and command equipment will not go on (the
burner stays off). If the NO is not closed (normally open), where it
should be closed when working, (insufficient air pressure) the
equipment carries out its cycle but will not switch on the ignition
transformer ignition and the gas pilot will not go on, with the result
that the burner locks off.
Adjustment before switching on the burner:
set the pressure switch at minimum.
Adjustment after burner calibration:
connect a manometer to the positive (+) pressure intake and another
manometer at the negative pressure (-) intake of the pressure switch.
Check at what point in the modulation there is the smallest pressure
difference (∆p) and adjust the pressure switch at the half-way point
of this difference.
Example: positive value + 1.5 mbar, negative value - 0.5 mbar
difference + 2 mbar, calibration 2:2 = 1 mbar
GAS PRESSURE SWITCH WORKING
The minimum and maximum gas pressure control switches
have the aim of preventing the burner from working when the
gas pressure goes outside the preset limits. The specific
working of the pressure switches naturally means that the
minimum pressure control switch uses the NO contact
(normally open) so that it is closed when the pressure switch
detects a pressure greater than that set. Similarly the
maximum pressure switch uses the NC contact (normally
closed) so that it is closed when the pressure switch detects
a pressure below that set. The adjustment of the minimum
and maximum gas pressure switches must therefore take
place when the burner is being tested, according to the
pressure found from time to time. The pressure switches are
connected up in such a way that the triggering of any of these
switches, (opening of the circuit), when the burner is firing,
will result in immediate burner shut-down.
Adjustment before switching on the burner: adjust the
minimum pressure switch at the scale's minimum and adjust
the maximum pressure switch at the scale's maximum.
Adjustment after burner calibration: With the burner at its
maximum output, adjust the minimum pressure switch by
increasing the calibration until the burner switches off, read
the calibration setting on the adjustment ring nut and set this
to 5 mbar less. With the burner off, adjust the maximum pressure
switch by reducing the calibration until the NC contact (normally closed) opens. Read the value on the adjustment ring
nut and adjust this by increasing it by 5 mbar.
Note: the pressure switch will be for minimum pressure if there is only one of these mounted on the gas train.
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