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9 - UNIT OPERATION WITH OPTION 154
9.1 - Operating principle
The units have been designed to optimise the operation of
systems, using drycoolers as heat rejection system.
With a variable-speed condenser water pump integrated into the
unit the complexity of traditional systems, using a three-way valve
has been reduced.
The installation of an operational system is limited on the
condensing water loop side to connect the drycooler entering and
leaving water piping to the unit.
The Touch'Pilot control of the unit includes algorithms to permit
constant automatic optimisation of:
- drycooler fan stage operation
- water flow rate variation in the loop between the condenser
and the drycooler.
Parallel control of the fan stages (up to 8 stages maximum) and
of the variable water flow rate of the loop permit year-round system
operation down to -10 °C outside temperature without any
additional control.
9.2 - Communication to control the drycooler
The electronic board specifically integrated in the control box of the
drycooler, by an option selection on the manufacturer drycooler,
and a communication LEN bus connected to the microprocessor
board of the unit is used for the overall system control.
Pay attention that Dry cooler and Chiller have to be both equipped
with the option 154.
The option is supplied in the manufacturer's drycooler control box.
Connect the unit to board AUX1 in the drycooler, using a
communication cable. the communication cable should be connect
to the plug with 3 points Wago type (5 mm spacing or equivalent).
the communication cable should be a shielded type.
The Touch'Pilot control optimises system operation to obtain the
best efficiency with variation of the water flow rate and the number
of fans required for any thermal load and outside temperature
conditions.
The electronic board (AUX1) integrated in the control box of the
drycooler has analogue inputs for outside air temperature and
drycooler leaving water temperature sensors, as well as eight digital
outputs permitting control of up to eight fan stages.
9.3 - Configuration of the number of fan stages
and the automatic changeover of the fan stages
Please refer to the instructions in the Touch'Pilot IOM for the
configuration of the number of fan stages to be controlled. It is
enough to enter the number of fan stages of the drycooler in the
Touch'Pilot service menu. The number of digital outputs controlling
the fans are activated by the control.
Touch'Pilot controls the automatic switching of all fan stages, based
on operating time and number of start-ups of the different stages.
This function prevents fan motors from only running a little or not at
all and the shafts seizing up, especially during periods with a low
cooling demand, when the outside temperature is low. Switching is
often specified by the drycooler manufacturers to ensure a long
operating life of fan motors that are only used a little or not at all in
these particular operating conditions.
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9.4 - Fan stage assignment
The minimum configuration of the number of fan stages is 2 for
correct operation.
Depending on the drycooler capacity the number of fans can be
between 2 and 8. They can be controlled by one fan or by linked
pairs, if necessary.
A drycooler with 4 or 6 fans installed in series for example along the
length of the unit will result in a configuration of 4 or 6 fan stages.
Reciprocally a drycooler with 8 or 12 fans arranged in pairs along
the length of the unit will also result in a configuration of 4 or 6 fan
stages.
Configuration with 4 and 6 stages (min. 2 - max. 8)
A
1
Fans linked in pairs - 4 and 6-stage configuration
(min. 2 - max. 8)
1
A
1
Legend
A
Entering and leaving water manifold side
1 to 6
Fans
9.5 - Drycooler installation on 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 unit pumps.
- Maximum drycooler elevation in relation to the unit (relief valve
at 4 bar on the unit water circuit).
- Fan stage control (see "Fan stage control").
- Good positioning of the outside air temperature and drycooler
leaving water temperature sensors.
2
3
4
5
2
3
4
5
2
3
4
5
6
6
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