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7.5 - Protection against cavitation (with option 116)
To ensure the durability of pumps fitted on the integrated hydraulic
modules, the control algorithm of 30RQM/30RQP units includes
protection against cavitation. It is therefore necessary to ensure
a minimum pressure of 60 kPa (0.6 bar) at the pump inlet both
when shut down and during operation. A pressure below 60 kPa
will prevent unit start-up, or will cause an alarm and shut-down.
A pressure below 100 kPa will trigger an alert on the user interface.
To obtain an adequate pressure, it is recommended:
•
To pressurise the hydraulic circuit between 100 kPa (1 bar)
and 400 kPa (4 bar) maximum at the pump inlet;
•
To clean the hydraulic circuit during water filling or after
any modifications are made;
•
To regularly clean the screen filter.
7.6 - Operation of two units in Master/Slave mode
(option 58)
The customer must connect both units with a communication
bus in 0.75 mm² twisted, shielded cable (contact Carrier Service
for the installation).
All the parameters required for the master/slave function must be
configured using the Service configuration menu. All remote
controls of the Master/slave assembly (start/stop, setpoint, load
shedding, etc.) are managed by the unit configured as the Master
and must only be applied to the Master unit.
7.6.1 - Units delivered with the hydraulic kit
Operation in Master-Slave mode is only possible when the units
are installed in parallel:
•
The master-slave assembly is controlled on the water
inlet without any additional sensors (system return) (see
example 1).
•
Control of Master and Slave on the water outlet is possible
by adding two additional sensors in the common supply
pipe work (see example 2).
Each unit controls its own water pump.
7.6.2 - Units delivered without the hydraulic kit
In the case of units installed in parallel and if there is only one
common pump installed by the installer, isolating valves must
be installed on each unit. These should be controlled (opened
and closed) using the control for the relevant unit (in this case,
valves will be controlled using the dedicated water pump
outputs). Consult the 30RQM/30RQP controller manual for
details of the connections.
The control of a variable speed pump must be, in this case, carried
out by the unit via the 0-10 V dedicated output of the Master
unit (control on Delta T° only).
An installation in series is only possible with a fixed speed pump
(example 3):
•
The operation of the pump will be controlled by the Master
unit.
•
The Master-Slave assembly is controlled on the water outlet
without additional sensor.
•
The installation must be carried out only according to the
diagram given in the example 3.
IMPORTANT:
Both of the units must be equipped with option 58 to allow
master/slave operation.
Example 1: Operation in parallel -
control on water inlet for a hydraulic kit
1
Example 2: Operation in parallel -
control on water outlet for a hydraulic kit
1
T
T
2
2
33
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