30Wg Units Without Evaporator And Condenser Pump, Three-Way Valve Configuration For Low Outside Temperature Application; Drycooler Installation On 30Wg Units; 30Wga Unit Operation With A Remote Air-Cooled Condenser (Option 154); Operating Principle - Carrier 61WG 020 Installation, Operation And Maintenance Instructions

14.5 - 30WG units without evaporator and condenser
pump, three-way valve configuration for low outside
temperature application
30WG units can be supplied from the factory without evapo-
rator and condenser pump. If year-round low-temperature
operation is planned, the unit will be installed with a three-way
valve that is not supplied with the unit.
In this case Pro-Dialog+ should be configured for three-way
valve system control from an analogue 0-10 volt output on
the Carrier NRCP type master board. An adequate
condensing temperature will be maintained with constant
condenser flow rate. This configuration permits year-round
system operation down to -20 °C outside temperature.
Control and changeover of the fan stages, described in chapter
"Configuration of the number of fan stages and automatic
changeover of the fan stages" is identical in this case.

14.6 - Drycooler installation on 30WG units

For the drycooler installation follow professional guidelines.
• Water pipe sizing
• Maximum piping and shut-off valve pressure drops based
on the available pressure of the 30WG pumps
• Maximum drycooler elevation in relation to the unit
(safety valve at 3 bar on the 30WG water circuit).
• Fan stage control (see "Fan stage control").
• Good positioning of the outside air temperature and
drycooler leaving water temperature sensors.
15 - 30WGA UNIT OPERATION WITH A REMOTE AIR-
COOLED CONDENSER (OPTION 154)

15.1 - Operating principle

30WGA units have been specially designed to optimise the
operation of split installations, using air-cooled condensers
as the chiller heat rejection system. The installation of an
operational system is limited to the connection of the air-cooled
condenser inlet and outlet piping to the 30WGA unit.
The Pro-Dialog+ control system of the 30WGA includes a
logic to permit control the different fixed and variable-speed
fan variants.

15.2 - Lead fan

The physical position of the air-cooled condenser with fixed
or variable-speed fans depends on the position of the leaving
liquid refrigerant manifold. In all cases there is always a so-
called lead fan. This is the fixed or variable-speed fan that is
physically the closest to the leaving liquid refrigerant
manifold.
This ensures optimum subcooling on the condenser outlet
side, especially at part load. This is the first fan to start in each
circuit and the last fan to stop. A fan configuration with fixed-
speed fans permits year-round system operation down to 0
°C outside temperature.
A fan configuration with a variable-speed lead fan permits
year-round operation down to -10 °C outside temperature.
42
15.3 - Auxiliary electronic board (AUX1) - analogue and
digital inputs and outputs - to control the remote air-
cooled condenser
J2 J3
CH -- CH -- CH -- CH -- CH -- CH
1 2 3 4 5 6
• Connector J2: Digital outputs CH 1 to 4 for fan stages
1 to 4.
• Connector J3: Digital outputs CH 5 to 8 for fan stages
5 to 8.
• Connectors J4 and J5: Analogue outputs 0-10 V dc for
fan speed variation of the air-cooled condensers.
• Connector J6: Analogue input CH 12 for outside
temperature sensors.
• Connector J9: Communication bus with NRCP master
board of the 30WGA unit.
The electronic board specifically integrated in the control
box of the condenser and a communication bus connected
to the microprocessor board of the 30WGA is used for the
overall system control.
The option supplied with the cooling unit must be installed
in the condenser control box. Connect the unit to board
AUX1 in the condenser, using a twisted and shielded type
RS485 communication bus cable.
Pro-Dialog+ continuously optimises system operation to
obtain the best system efficiency by controlling the number of
fans required for any thermal load and outside temperature
conditions.
The outside air temperature sensor is required for correct
system operation (EXV, fans, condensing temperature,
setpoint). The position of the temperature sensor must be
chosen with great care and must be representative of the
outside temperature (limit any other source that could have
a negative influence on the control: gusts of wind, other heat
sources such as sun radiation and hot air recycling).
15.4 - Configuration of the number of fan stages and
fan type based on the air-cooled condenser model used
in the installation
Please refer to the instructions in the Pro-Dialog+ IOM for
the 61WG/30WG/30WGA units to carry out the parameter
setting of the air-cooled condenser used in the installation:
• Use of speed variation on the lead fan(s)
• Number of fixed-speed fans
Based on the parameter setting used, the arrangement of
the digital and corresponding analogue outputs
controlling the fans will be activated by the control.
STATUS SIO
CH14
CH13
J4 J5 J6
-- CH -- CH -- CH CH
CH CH
-- -- --
7 8
9 10
11 12
T
P
V
T
P
V
--