30
To set the circuit loading sequence
1. Navigate to the Configuration menu.
2. Select
General Config
(GENCONF).
3. Set
Staged Loading Sequenc
e [seq_typ].
Staged loading sequence [seq_typ]
No/Yes
No
8.9.2 - Capacity for multi-circuit unit
The circuit lead/lag function determines the lead and lag
circuit of the unit. This function controls the start/stop
sequence of two refrigeration circuits called circuit A and
circuit B.
The circuit authorised to start first is the lead circuit. Lead
circuit is used first for capacity increases and at the same
time should be decreased first when decreasing capacity.
The lead/lag circuits can be selected manually or
automatically (
Cir Priority Sequence
,
GENCONF
–
General Config).
•
Manual lead/lag circuit determination
: Circuit A or
circuit B selected as the lead circuit. The selected
circuit takes priority over another circuit.
•
Automatic lead/lag circuit determination
: The control
system determines the lead circuit to equalise the
operating time of each circuit (value weighted by the
number of start-ups of each circuit). As a result, the
circuit with the lowest number of operating hours
always starts first.
To set circuit priority
1. Navigate to the Configuration menu.
2. Select
General Config
(GENCONF).
3. Set
Cir Priority Sequenc
e [lead_cir].
Cir Priority Sequence [
lead_cir]
0
Auto
1
Circuit A lead
2
Circuit B lead
8.10 - Free cooling option
30RBS chillers and 30RQS heat pumps may be fitted with
a dry cooler that enables power consumption reduction
which amounts to energy and cost savings (FREE
COOLING).
The installation of a dry cooler allows for “free cooling”,
i.e. a method of using low outdoor air temperature as an
aid to chilling water that is later used in the air-
conditioning system.
The system is the most effective when the outdoor air
temperature is below 0°C (32°F).
Starting free cooling
The free cooling mode is ENABLED when the free
cooling OAT [fc_oat] is below the water loop temperature
and the start threshold:
fc_oat < fc_wloop – fc_start
fc_oat: Free Cooling OAT
fc_wloop: Free Cooling Water Temperature
fc_start: Free Cooling Start Threshold (service access only)
Note: [fc_wloop] and [fc_oat] temperatures measured by
the control are read-only values that can be verified in
the DC Free Cooling Status menu (FCOOL_ST).
To verify Dry Cooler water loop temp.
1.
Navigate to the Main menu.
2. Select
DC Free Cooling Status
(FCOOL_ST).
3. Verify
FC Water Loop Temp [fc_wloop].
FC Water Loop Temp [fc_wloop]
°C / °F
To verify Free Cooling OAT
1. Navigate to the Main menu.
2. Select
DC Free Cooling Status
(FCOOL_ST).
3. Verify
Free Cooling OAT [fc_oat].
Free Cooling OAT [fc_oat]
°C / °F
Stopping free cooling
If it turns out that the cooling power of the dry cooler is
not enough in order to reach the cooling setpoint, then the
mechanical cooling will be started.
Free Cooling is normally stopped when the free cooling
OAT [fc_oat] is above the water loop temperature and the
start/stop threshold:
fc_oat > fc_wloop - fc fc_stop
fc_oat: Free Cooling OAT
fc_wloop: Free Cooling Water Temperature
fc_start: Free Cooling Start Threshold (service access only)
fc_stop: Free Cooling Stop Threshold (service access only)
When FC capacity is at 100%, then mechanical cooling can
be started.
8.11 - Night mode
Night mode allows users to configure the unit to operate
with specific parameters in a specific time period. During
the night period, the unit capacity is limited. The number
of operating fans is reduced (in cooling mode only).
The night period is defined by a start time and an end time
that are the same for each day of the week. The Night
mode settings or the maximum capacity value can be
configured via the Configuration menu (GENCONF
–
General Config). Only logged-in users can modify the
night mode settings.
