56
Setting Pressure Switches and
Control System
Setting of the oil pressure switch
The oil pressure switch is factory-set.
The supply pressure switch is set in
such a way, that perfect atomization is
guaranteed. The return pressure switch
is factory-set to 2 bar.
The pre-set return pressure should nor-
mally be 1 bar above the loop feeder
system. After having set the correct
pressure ensure that the
setting screw is securely locked.
Setting of the gas pressure switch
Remove the protective hood. Measure
the gas flow pressure at full load and
reduce by 20 % to obtain the shutdown
pressure.
Proceed with turning the scale disk until
the desired shutdown pressure is oppo-
site to the arrow. Note that scale values
are approximate values only.
Then slowly close the gas stop valve
until the desired shutdown pressure has
been reached. Readjust the scale disk
until the burner stops.
Put the protective hood back in place
again and tighten bolts.
Setting of the air pressure switch
The differential pressure between bur-
ner housing (overpressure) and air box
(subatmospheric pressure) is measured
with the burner in full-load condition.
The pressure setting of the air pressure
switch must therefore be smaller than
the differential pressure measured. For
adjustment, remove the protective hood
and turn the setting scale accordingly.
Switching functions of air pressure
switch/gas pressure switch
With increasing pressure:
P1
opens
P2
closes
With decreasing pressure:
P1
closes
P2
opens
An
industrial controller type KS 92
is
used for the steplessly adjustable bur-
ners. This controller has been specifi-
cally designed for use with burner
systems. It is mainly employed for tempe-
rature or pressure control operations in
conjunction with burners with a steadily
adjustable fuel throughput rate. A specific
software system is provided for adjusting
the controller to the controlled variable,
the desired setpoint range and the way of
actual-value recording.
Technical documentation
KS 92 PMA
Infinitely variable control
(modulating) with RWF 32 controller
A universal controller type RWF 32 can
also be used with infinitely variable con-
trollable burners. This controller is spe-
cially designed for furnace temperature
and pressure control of burners using
constantly changing types of fuel.
Depending on the use, the RWF 32 will
function as either PID, PD or P control-
ler. As the P part, which is correcting
time and the D part can be adjusted to
cover a wide range of limits, it is possi-
ble to adapt the control behaviour of the
installation to exact standards. The ope-
rating time of the drive for compound
control of fuel and air must be at least 2
secs. for the "small flame - nominal load
setting" range.
The actual value reading (temperature,
pressure or combustion chamber pres-
sure) is achieved by means of sensors
and range or zone plugs in the form of a
resistance value. The control output of
the controller is a floating three-point
switch used to control reversible servo-
motors. The control signals for the
actuating direction OPEN (y1) and
CLOSED (y2) are displayed by LEDs,
whilst the adaptation of the controller to
the control led variable and the required
specified value range is effected via the
so-called range or zone plugs, which
form the sensor part of the controller
measuring bridge. The range or zone
plug is also fitted with the setpoint scale.
On the other hand, the setpoint value
generator itself, which can be changed
to be a remote setpoint value generator,
is a fixed component of the controller.
Setting the controller
Setting a complete, infinitely variable
heating installation required excellent
technical and controller knowledge. The
actual setting and commissioning of the
installation is made considerably easier
by the special setting instructions
issued with the RWF 32 controller.
Comprehensive special issues are
available if required.
The differential pressure between the
burner housing (excess pressure) and
the air receiver (negative pressure) is
measured during the full load adjust-
ment. The pressure set at the air pres-
sure switch must be below the
measured differential pressure. To carry
out the setting remove the protective
cover and turn the setting scale as
required.
Gas pressure switch
P
1
2
P
Air pressure / gas pressure
switch circuit
KS 92
Oil pressure switch
