CIAT PRO-DIALOG+, Инструкция по эксплуатации

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5.9 - Capacity control
This function adjusts the number of active compressors to keep
the heat exchanger water temperature at its setpoint. The preci
-
sion with which this is achieved depends on the capacity of the
water loop, the flow rate, the load, and the number of stages avail
-
able on the unit. The control system continuously takes account
of the temperature error with respect to the setpoint, as well as
the rate of change in this error and the difference between en-
tering and leaving water temperatures, in order to determine the
optimum moment at which to add or withdraw a capacity stage.
If the same compressor undergoes too many starts (per hour)
or runs below one minute each time it is started this automati-
cally brings about reduction of compressor starts, which makes
leaving water temperature control less precise.
The high pressure, low pressure or defrost unloading functions
can also affect temperature control accuracy. Compressors are
started and stopped in a sequence designed to equalise the
number of start-ups (value weighted by their operating time).
5.10 - Head pressure control
The head pressure is independently controlled for each circuit,
based on the saturated condensing temperature value.
5.11 - Defrost function
This function only applies to heat pumps. Defrost is activated,
when the unit is in heating mode to reduce frost build-up on the
air heat exchanger. The defrost cycle can only be applied to
one circuit at a time. During the defrost cycle the fans of that cir-
cuit are stopped, and the four-way refrigerant valve is reversed,
forcing the circuit to cooling mode. The fan can temporarily be
restarted during the defrost cycle. The defrost cycle is fully auto-
matic and does not require any setting.
5.12 - Desuperheater option
In units with desuperheater it is possible to reclaim the hot wa-
ter. To optimise this option, the condensing setpoint should be
increased (chapter 4.9.4 setpoint menu, sct_min) while the des
-
uperheater heat exchanger is used. Optimising desuperheater
condensation is activated via dry contact DSHTR_SW
(see chapter 3.6.1).
5.13 - Additional electric heater stage control
The heat pump units can control up to four additional electric
heating stages (accessory).
The electric heating stages are activated to complement the
heating capacity when the following conditions are satisfied:
• The unit uses 100% of the available heating capacity, or
the unit is limited in its operation by a protection mode
(low suction temperature, hot gas or defrost sequence in
progress protection), and in all cases cannot satisfy the
heating load.
• The outdoor temperature is below a configured threshold
(see HCCONFIG configuration).
• The unit demand limit is not active.
The user may configure the last available electric heating stages
as a safety stage. In this case, the safety stage is only activated
in addition to the other stages if there is a machine fault, prevent-
ing the use of the heating capacity. The other electric heating
stages will continue to operate as described above.
5.14 - Control of a boiler
NOTE: The control of the electric heating stages or of a
boiler is not authorised for slave units.
The unit can control the start-up of a boiler, if it is in heating mode.
When the boiler is operating, the unit water pump is stopped.
A heat pump unit and a boiler cannot operate together. In this
case the boiler output is activated in the following conditions:
• The unit is in heating mode, but a fault prevents the use
of the heat pump capacity.
• The unit is in heating mode, but works at a very low
outdoor temperature, making the heat pump capacity
insufficient. The outdoor air temperature threshold for use
of the boiler is fixed at -10°C, but this value can be
adjusted in the HCCONFIG menu.
5.15 - Master/slave assembly
Two Pro- units can be linked to produce a master/slave
assembly. The two machines are interconnected over the pro-
prietary protocol communication bus. All parameters required for
the master/slave function must be configured through the Service
configuration menu.
Master/slave operation requires the connection of a tempe-rature
probe at the common manifold on each machine, if the heat ex
-
changer leaving water temperature is controlled. It is not required,
if the entering water temperature is controlled.
The master/slave assembly can operate with constant or varia-
ble flow. In the case of variable flow each machine must control
its own water pump and automatically shut down the pump, if
the cooling capacity is zero.
For constant flow operation the pumps for each unit are continu
-
ously operating, if the system is operating. The master unit can
control a common pump that will be activated, when the system
is started. In this case the slave unit pump is not used.
All control commands to the master/slave assembly (start/stop,
setpoint, heating/cooling operation, load shedding, etc.) are
handled by the unit which is configured as the master, and must
therefore only be applied to the master unit. They will be trans-
mitted automatically to the slave unit.
The master unit can be controlled locally, remotely or by Network
commands. Therefore to start up the assembly, simply validate
the Master operating type (Master) on the master unit. If the Mas-
ter has been configured for remote control then use the remote
volt-free contacts for unit start/stop.
The slave unit must stay in Network operating type continuously.
To stop the master/slave assembly, select Local Off on the mas-
ter unit or use the remote volt-free contacts if the unit has been
configured for remote control.
One of the functions of the master unit (depending on its configu
-
ration) may be the designation, whether the master or slave is to
be the lead machine or the follower. The roles of lead machine
and follower will be reversed when the difference in running hours
between the two units exceeds a configurable value, ensuring that
the running times of the two units are automatically equalised.
5 - PRO- CONTROL OPERATION
EREBA ACCESS EN - 20