C0240111-04-05-GB
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ADJUSTMENT METHOD FOR CENTRIFUGE COMPRESSORS:
The W3000 controller can manage units with centrifuge compressors.
The units are combination-adjusted (steps and continuously), with steps for activating the compressors.
Some diagrams outlining how this works are shown below.
Suppose we have a single compressor unit (
figure 5.5)
.
s e t p o in t
(0 % )
S e t p o in t + B a n d a
p ro p o rzio n a le (1 0 0 % )
M in
M a x
P o te n za
a s s o rb ita
[K w ]
% a c c e n s io n e
c o m p re s s o re
P o te n za
ric h ie s ta d e l
te rm o re g o la to re
[% ]
Figure 5.5:
adjustment for a single-compressor unit. Min=theoretical minimum electrical power absorbed by a
compressor, Max=theoretical maximum electrical power absorbed by a compressor
Absorbed
power
[kW]
% compressor
switch-on
Set point + Prop.
band (100%)
Thermoregulator
power
request
[%]
Let us take a close look at how the compressor is activated (
figure 5.6
).
When the system return temperature lies in zone A (figure 5.6a) or less than the setpoint, the
compressor is off. The amplitude of zone A normally coincides with the temperature difference at the
evaporator with the compressor running at minimum power.
When the return temperature exceeds zone A (figure 5.6b), the compressor is switched on and then
switches off if the temperature falls below the setpoint.
If the return temperature lies in zone B (figure 5.6c), the power of the compressor is modulated
according to system requirements.
set point
set point
+
Proportional band
start compressor 1
t [min]
Tin [°C]
A
OFF
ON
set point
set point
+
Proportional band
start compressor 1
t [min]
Tin [°C]
OFF
ON
A
Figure 5.6 a)
Figure 5.6 b)
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