Intercooler; Energy Saving - Daikin Hubbard GCU2040PXB1 Installation, Commissioning And Maintenance Manual

6.8 Intercooler

pRack pR300T manages the gas cooler much the same way as pRack
PR300 does for the condensers on a second condenser line, and activation
is only available via the Wizard:
Wizard
Configure intercooler
between the suction
lines?
Only temperature control is available. The control variable is therefore
the intercooler outlet temperature (measured by the probe, and not a
converted pressure value).
Request
100.0%
Setpoint
Differential
Fig. 6.af
If the intercooler temperature probe is faulty or not fi tted, the compressor
discharge temperature on the low temperature line (L2) can be used,
where confi gured.
If, on the other hand, the low temperature compressor discharge
temperature probe (L2) is not fi tted or has an alarm, the controller can
use the value converted from the suction pressure on the medium
temperature line (L1).
The fans can also be managed with modulating operation by inverter; in
this case, there is only one 0 to 10 V modulating output, while a diff erent
input can be used for each fan as regards the alarm signal. The function can
be enabled and the related parameters set from main menu branch D.b.
The intercooler can be confi gured only if the second suction line is
available (therefore on the pLAN 1 boards, if the double suction line is
managed using one board, or pLAN 2 boards if the double suction line is
managed using two boards).
The following functions are not available for the second line of fans
(intercooler)::
•
fl oating condensing;
•
set point compensation;
•
chillbooster;
•
heat recovery;
•
backup pressure probes;
•
split condenser.
The pressure prevent function will be managed as confi gured on screen
Gbb07:
L2-Prevent
Booster system
Use L1 suct.probe for
condensing line 2:
(Prevent disabled:
disch.press.needed)
Selecting NO means the low temperature line discharge pressure (L2)
needs to be confi gured for managing the PREVENT function, otherwise
PREVENT will not be activated.
If the fi eld is set to YES, the PREVENT function will work using the medium
temperature line suction pressure (L1).
Copyright HPL March 2021
Ib98
NO
Intercooler temperature
Differential
Gbb07
NO

6.9 Energy saving

pRack PR300T can activate energy saving functions by adjusting the
suction and condensing pressure set points. The suction and condensing
pressure set points can be applied with two diff erent off sets, one for the
closing period and one for the winter period, activated by:
•
Digital input
•
Time band
•
Supervisor
In addition, the suction pressure set point can be modifi ed from analogue
input, applying a linearly variable off set based on the value read by a
probe. As well as set point compensation from digital input, scheduler,
supervisor or analogue input, two further energy saving functions
are available, fl oating suction and condensing pressure set point. The
functions can be enabled and the related parameters set in main menu
branch C.a.d/C.b.d and D.a.d/D.b.d.
6.9.1 Set point compensation
Compensation from digital input, scheduler or supervisor is similar for suction
and condensing pressure set points, consequently the following description
applies to both. Two diff erent off sets can be defi ned, which apply to:
•
Closing periods, defi ned by the scheduler, activation of a digital input
or supervisor
•
Winter period, defi ned by the scheduler
The two off sets add to the set point defi ned by the user when the
corresponding condition is active.
Example 1: closing off set 0.3 barg, winter off set 0.2 barg, suction
pressure compensation from scheduler and from digital input
activated. When the digital input is activated, for example with a day/
night function, 0.3 barg is added to the operating set point, and when the
winter period is in progress a further 0.2 barg is added. The operation can
be schematised in the following fi gure:
Digital Input
ex.: day/night
Summer/Winter
Setpoint
Note: the same digital input is used for set point compensation on
each line, so if suction and condensing pressure set point
compensation is activated by digital input, both compensation functions
are active at the same time.
If compensation from analogue input is enabled, a off set that is linearly
variable to the value read by a dedicated probe can be applied to the
suction pressure set point, as shown in the fi gure.
Offset
Offset max
Offset min
Lower value
Compensation from analogue input applies to setpoint:
•
suction
•
gas cooler
•
HPV minimum.
These compensations can be enabled separately.
43
Page 92 of 172
User setpoint +0,5 barg
time
Fig. 6.ag
Probe value
Upper value
Fig. 6.ah
P4114S Rev 03
pRack PR300T +0300018EN rel. 1.5 - 02.05.2017
ENG