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4.4 Control options (modes of
operation)
The usability of the modes of operation de-
scribed below depends on the actually availa-
ble physical system implemantation, i.e. the
number of available nozzle sections. On the
other hand, the system must be engineered
for the respective number of loads. The num-
ber of loads required was specified when the
system was ordered.
Basic prerequisite for operating the system is
the enabling via the safety (interlock) system
(terminals 1/2 on terminalblock X1) by a max.
hygrostat or other on-site disengaged locking
mechanisms.
4.4.1 Supply air humidification (stan-
dard operation)
For controlling the system, an on-site control
signal of 0...10 V (0...20 mA/ 0...140
Ω
) is
required. All nozzles provided are driven with
an atomisation pressure of 25...75 bar pro-
portionally following the resulting actuator
signal. The system reaches maximum
possible humidification output at 100 percent
of the drive signal.
4.4.2 Supply air humidification 2 load
mode (normal requirements;
comfort humidification)
This mode is only available on a system fea-
turing at least 2 independant nozzle sections.
For controlling the system, an on-site control
signal of 0...10 V (0...20 mA / 0...140
Ω
) is
required that is transfomed in an internal
actuator signal by the control electronics.
In the range from 0 to approximately 50
percent of the actuator signal, only one nozzle
section is driven with an atomisation pressure
of 25...75 bar. This range is called „1
st
load“.
When the actuator signal reaches 50 percent
plus
hysteresis
(switching point 1 plus
hysteresis), the pumping station switches on
the second nozzle section and reduces the
pressure to 25 bar. Up to an actuator signal of
100 percent, the output pressure on the
nozzles rises proportionally up to 75 bar and
the system reaches the maximum possible
humidification output. Beyond the switching
point the system works in the „ 2
nd
load“.
Hysteresis
of the switching threholds is es-
sential in order to prevent the control from os-
cillating. It is relevant for all of the load
switching points, i.e. for more than 2 loads as
well. Factory setting is 1.0%, i.e. the threshold
for switching to the 2
nd
load mode is 51 % up-
wards and 49 % downwards.
4.4.3 Supply air humidification 3 load
mode (process humidification)
This mode is only available on a system fea-
turing at least 3 independant nozzle sections.
For controlling the system, an on-site control
signal of 0...10 V (0...20 mA / 0...140
Ω
) is re-
quired that is transformed to an internal actua-
tur signal.
In the range from 0 to approximately 30 per-
cent of the actuator signal (switchpoint 1),
only one nozzle section is driven with an ato-
misation pressure of 25...75 bar, the so called
„1
st
load“. When the actuator signal exceeds
this level, the pumping station switches on the
second nozzle section and reduces the pres-
sure to 25 bar. Beyond that up to approxi-
mately 60 percent , the nozzle output
pressure is proportionally increased until it
reaches its maximum of 75 bar. This is the
range of the „2
nd
load“. Beyond that level the
third nozzle section is switched on („3 rd
load“) while the pressure is decreased to 25
bar again. Up to an actuator signal of 100 per-
cent, the output pressure on the nozzles rises
proportionally up to 75 bar and the system
reaches the maximum possible humidification
output.
