28
5.3 - Evaporator water pump control
The evaporator water pump is started when the unit is in the
running mode described above or in delay at start-up mode (i.e.
mode 7). Since the minimum value for the delay at start-up is 2
minutes (configurable between 2 and 15 minutes), the pump
will run for at least two minutes before the first compressor
starts. The pump is kept running for one minute after the unit
goes to stop mode. The pump keeps working when the unit is
switching from heating to cooling mode or vice-versa. It is
turned off if the unit is shut down due to an alarm unless the
fault is a frost protection error or risk of freezing.
5.4 - Condenser water pump control
Only available on water-cooled units.
The condenser pump can be controlled by two modes, depend-
ing on the configuration (only accessible by Carrier Service).
1 - Control based on unit start/stop control. In this case it is
controlled in the same way as the evaporator pump.
2 - Control based on compressor status. In this case the pump
is activated at the same time as the first compressor. It
only switches off when no compressor is activated.
5.5 - Control point
Control point represents the leaving water temperature that the
unit must produce.
• In cooling mode: control point = active setpoint + reset
• In heating mode: control point = active setpoint - reset
5.5.1 - Active setpoint
Two setpoints can be selected as active in cooling mode.
Usually, the second setpoint is used for unoccupied periods or
for ice storage (medium or low brine unit). A single setpoint is
available in heating mode.
Depending on the current operating mode, the active setpoint
can be selected with the operating type selector button, or with
the user’s volt-free contacts, or with network commands (see
section 4.2.7).
5.5.2 - Reset
Reset means that the active setpoint is modified in such a way
that the capacity required by the unit is less (in cooling, the
setpoint is increased, and in heating it is lowered). This
modification is in general a reaction to a drop in the load. For
the PRO-DIALOG control system, the source of the reset can
be configured: it can be delivered either by an external 0-10 V
d.c. signal (e.g. outside temperature probe) or by the return
water temperature. In both cases the reset parameters, i.e.
slope, source and maximum value, are configurable in the
Setpoints menu (see section 4.2.7) and are also independent for
the heating and cooling modes.
5.6 - Demand limit
Generally, demand limit is used by an energy management
system in order to restrict the unit electricity consumption.
The PRO-DIALOG control system for 30GX & 30HX
provides two methods of demand limit:
5 - PRO-DIALOG PLUS CONTROL OPERATION
5.1 - Start/stop control
The unit is in stop mode and is not authorised to start up if at
least one of the following conditions is met:
• The unit is in Local Off operating type (LOFF): mode 1 is
active.
• The unit is in operating type Remote (rEM) and the controller
has received a stop command over a volt-free contact
connected to the customer terminal block: mode 3 is active.
• The unit is in operating type CCN (CCn) and either:
- the controller has received a stop command over the
network: mode 2 is active; or
- the controller has received a start command over the
network but start/stop control by volt-free contact is
authorised in CCN mode and the controller has received
a stop command over a volt-free contact connected to
the customer terminal block: mode 2 is active.
• The delay at start-up has not expired: mode 7 is active.
• The unit is in the process of switching from heating to
cooling mode: it has completely stopped before restarting.
• CCN has commanded an emergency shutdown (EMSTOP
activated).
• The unit is totally shut down due to an alarm.
The unit is authorised to start if it is not in stop mode (see
above) and if one of the following conditions is met:
• The unit is in Local operating type (L-C1, L-C2, L-H, LC1r,
LC2r): mode 4 is active.
• The unit is in Remote operating type (rEM) and the controller
has received a start command over a volt-free contact
connected to the customer terminal block: mode 6 is active.
• The unit is in CCN operating type (CCn) and the controller
has received a start command over the network, and either:
- start/stop control by volt-free contact is not authorised in
mode CCN: mode 5 is active; or
- start/stop control by volt-free contact is authorised in
mode CCN and the controller has received a start
command over a volt-free contact connected to the
customer terminal block: mode 5 is active.
NOTE: In CCN operating mode, it is possible to authorise unit
start/stop over a volt-free contact connected to the customer’s
terminal block. This configuration (which must be carried out
by Carrier Service) is exceptional and generally only used for
controlling a master unit in a master/slave grouping (see
section 5.18).
5.2 - Heating/cooling selection
On heat pumps, heating/cooling selection can be controlled
differently depending on the active operating type:
• Locally on the unit, using operating types L-C1, L-C2, LC1r
and LC2r (for cooling) and L-H (for heating).
• Remotely using the heat/cool selection volt-free contact when
the unit is in Remote operating type (rEM).
• Via a CCN command when the unit is in CCN operating type
(CCn).
The current heat/cool operating mode on the unit is indicated
by item 4 in the Information menu and by the heat/cool LEDs
on the summary interface.
To Next Page
Loading...
Need help?
General
