Gas Cooler - Daikin HUBBARD HCU2040PXB1 Installation, Commissioning And Maintenance Manual

Alarms
pRack PR300T can manage, in addition to the common alarms for all
types of compressors (see chapter 8 for details), some specifi c alarms for
Digital Scroll™ compressors:
•
high oil temperature
•
oil dilution
•
high discharge temperature
These alarms are managed as specifi ed by the manufacturer of the
compressor, and therefore pRack PR300T can only enable or disable them.
Activation of these alarms requires an oil temperature probe, which
can also be the common probe (see the paragraph relating to oil
management) and the compressor discharge temperature probe.
Note: pRack PR300T does not manages the envelope for Digital
Scroll™ compressors and consequently there is no corresponding alarm
when operating outside the envelope.

6.5 Gas cooler

pRack pR300T manages the gas cooler in a manner that is completely
similar to the pRack PR300T for the condensers, with the only diff erence
being that in transcritical condition, since correspondence between
the pressure and saturated temperature is lost, the regulation is always
in temperature di default ma è possibile a partire dalla versione 3.1.5
regolare i ventilatori anche in pressure. The regulation variable, therefore,
is the output temperature from the gas cooler.
Up to 16 fans can be managed, also with inverter modulation. In the
event of modulation, the modulating output 0...10 V is unique while an
input can be managed for each fan for signalling the alarms.
The functionalities can be enabled and the relative parameters can be set
from main menu branch D.a.
6.5.1 Control
pRack PR300T can manage proportional band and Neutral zone control,
by pressure or temperature.
For details on the control modes, see the corresponding paragraph, while
below is the description only of the features relating to the fans.
Fan operation depending on the compressors
The operation of the fans can be bound to the operation of the
compressors by setting a parameter in main menu branch D.a.b/D.b.b, in
this case the fans only start if at least one compressor is on. This setting is
ignored if the fans are controlled by a dedicated pRack PR300T board and
the pLAN network is disconnected.
Fan operation with modulating device
If the fans are controlled by a modulating device, the meaning of the
parameters that associate the minimum and maximum values of the
device's modulating output and the minimum and maximum capacity of
the modulating device on screens Dag02 and Dbg02 is illustrated in the
following examples.
Example 1: minimum modulating output value 0 V, maximum value 10 V,
minimum modulating device capacity 0 %, maximum 100 %.
Analog output
Max output
value = 10 V
Min capacity = 0 %
Min output
value = 0 V
Setpoint
Differential
Copyright HPL March 2021
Max capacity = 100 %
Regulation
probe value
Differential
Fig. 6.y
Example 2: minimum modulating output value 0 V, maximum value 10 V,
minimum modulating device capacity 60 %, maximum 100 %.
Analog output
Max output
value = 10 V
Min output
value = 0 V
Setpoint
Differential
Example 3: minimum modulating output value 2 V, maximum value 10 V,
minimum modulating device capacity 60 %, maximum 100 %.
Analog output
Max output
value = 10 V
Min capacity = 60 %
Min output
value = 2 V
Setpoint
Differential
Cut-off
pRack PR300T manages a control cut-off for the fans; functions and
related parameter settings can be enabled from main menu branch
D.a.b/D.b.b. The operating principle of the cut-off function is shown in
the fi gure:
Regulation request
Max output
value
Cut-Off value
of request
Min output
value
Cut-Off
setpoint
Differential
A percentage of the control request and a cut-off set point can be set.
When the control request reaches the set cut-off value, this value is kept
constant until the control value falls below the cut-off set point, after
which it falls to 0 % and remains there until the request exceeds the cut-
off value again.
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Max capacity = 100 %
Min capacity = 60 %
Regulation
probe value
Differential
Fig. 6.z
Max capacity = 100 %
Regulation
probe value
Differential
Fig. 6.aa
Regulation setpoint
Differential
Fig. 6.ab
P4367 Rev 01
pRack PR300T +0300018EN rel. 1.5 - 02.05.2017
ENG
Regulation
probe value