Chillbooster; Double Line Synchronisation (Dss); Modulation; Hygiene Procedure - Carel PRK300L3FK User Manual

Modulation

pRack pR300 can manage up to 2 modulation functions, with either
direct or reverse operation. In both cases, a set point and a diff erential
can be set; the operation of the corresponding output is shown in the
fi gure for direct mode, with the cut-off function also enabled:
Direct modulation
MAX
MIN
(Cut-off
Value)
Hyster.
Differential
Fig. 6.ai
If an enabling variable has been set, the corresponding output is active if
the enabling is also active. For each modulation, a high alarm threshold
and a low alarm threshold can be set, and are absolute. For each alarm,
the activation delay and priority can be set. See chapter 8 for details on
the alarms. For modulation a minimum and maximum value can also
be set for the output, and the cut-off function can be enabled, with
operation as shown in the previous fi gure.
Alarms
pRack pR300 can manage up to 2 alarm functions, with settable digital
variable to be monitored, activation delay, priority and description. Each
generic function can be associated with a digital output for the activation
of external devices when the alarm is activated. One example of using the
generic alarm functions involves detecting gas leaks.
Scheduler
pRack pR300 can manager a generic scheduler that activates a digital output
at certain time bands. Up to 4 daily time bands can be set for each day of the
week, in addition operation of the generic scheduler can be linked to the
common scheduler, and consequently the output activated based on:
•
summer/winter
•
up to 5 closing periods
•
up to 10 special days
See paragraph 6.7.2 for details on the time bands.
6.6.5

ChillBooster

pRack pR300 can control the Carel ChillBooster, device used for evaporative
cooling of the air that fl ows through the condenser. ChillBooster can
be enabled and the related parameters set in main menu branch E.g.
ChillBooster is activated when two conditions exist:
•
the outside temperature exceeds a set threshold
•
the fan control request is at the maximum for at least a settable
number of minutes
The maximum request time starts counting again whenever the request
decreases, therefore the request must remain at the maximum for at least
the set time. Activation ends when the request falls below a set threshold.
pRack pR300 can manage an alarm digital input from ChillBooster, the
eff ect of which is to deactivate the device. For details see Chapter 8. As the
number of operating hours of ChillBooster is critical as regards formation
of scale on the condenser, pRack pR300 can manage the operating hour
threshold, which should be set to 200 hours.

Hygiene procedure

To avoid water stagnation in the pipes, a hygiene procedure can be
enabled that activates ChillBooster every day for a set time, if the outside
temperature is greater than a threshold.
Note: if the outside temperature probe is not confi gured or is
confi gured but is not working, ChillBooster operates based solely on the
control request, and the hygiene procedure can still be activated.
The only diff erence between probe not confi gured and probe not working
concerns the ChillBooster operating without temperature probe alarm,
which is only generated when the probe is confi gured but not working.
Regulation variable
Setpoint
ChillBooster as the fi rst stage in high pressure prevention
ChillBooster can be used to prevent high condensing pressure.
The parameters relating to this function can be set in branch G.b.a/G.b.b
in the main menu, after having enabled the ChillBooster function.
For details on the prevent function see paragraph 8.3.3.
Operation of ChillBooster as the fi rst stage in high pressure prevention is
Similar to the heat recovery function described in paragraph 6.6.3.
The function must be enabled and an off set must be set in relation to the
prevent threshold, while the diff erential is the same as set for the prevent
function.
6.6.6

Double line synchronisation (DSS)

pRack pR300 can manage, for two line confi gurations, several
synchronisation functions between the two lines:
•
Disable simultaneous compressors starts
•
Force the medium temperature line on if the low temperature line is
activated
•
Shutdown the low temperature line if the medium temperature line
has a serious alarm
•
Enable pump-down medium temperature line
The four DSS functions can be enabled independently and are useful for
booster or CO2 cascade system confi gurations:
Important: in the pRack pR300 software assumes that the medium
temperature line is line L1, while the low temperature line is line L2.
DSS can be enabled and the related parameters set in main menu
branch E.h.
47
ENG
P T
P T
Fig. 6.aj
P T
P T
P
T
Fig. 6.ak
pRack +0300025EN rel. 1.3 - 17.12.2015