Carel Hecu CO2 - Pressure Alarm Configuration and Types

48
ENG
Hecu CO
2
+0300085EN rel. 2.2 - 07.05.2019
After having selected a description pertaining to one group, no
descriptions from other groups can be selected for that alarm.
For example, the selection may be generic, or alternatively overload + oil.
Each alarm will have its own unique alarm screen, and this will include all
the descriptions associated with that alarm.
According to the number of alarms selected, the descriptions shown in
the table will be associated by default.
Default descriptions based on the number of alarms
Number of alarms Descriptions
1 Generic
2 Overload
HP-LP
3 Overload
HP-LP
Oil
4 Overload
HP
LP
Oil
Tab. 8.d
Note: an oil alarm can be interpreted as an oil level warning. When
the alarm is activated, an attempt is made to restore the level for a set
time before signalling the alarm and stopping the compressor.
If a modulating device is used to drive the compressors, additional alarms
are provided:
• compressor inverter warning, common for the entire suction line,
when using inverters
• oil crankcase temperature alarm, high discharge temperature.
Low superheat alarm
The low superheat alarm can also be enabled for parallel compressors, in
addition to the standard SSH-DSH alarm.
The alarm can be enabled and the settings made on the following screen:
The alarm threshold is the same as the one used for the SSH_DSH alarm.
8.3 Pressure alarms
Hecu CO2 can manage pressure alarms from a pressure switch or probe,
according to the following diagram.
Alarms from pressure switch:
• Low suction pressure
• High condensing pressure
Alarms from probe:
• Low suction pressure
• High suction pressure
• Low condensing pressure
• High condensing pressure
One possible example for the low pressure alarms is shown in the fi gure:
Pressure
Probe alarmPressostat alarm
LP
Dierential
Fig. 8.b
Pressure alarms from pressure switch
The parameters corresponding to these alarms can be set in branch
G.c.a/G.c.b of the main menu.
Low suction pressure from pressure switch
The low suction pressure alarm from pressure switch has the eff ect of
stopping all the compressors without observing the various times,
therefore when the digital input confi gured as the low pressure switch
is activated, all the compressors on the line aff ected are stopped
immediately.
This alarm features semi-automatic reset, and both the monitoring time
and the number of activations in the specifi ed period can be set. If the
number of activations is higher, reset becomes manual.
In addition, the delay after which the alarm is activated on both start-up
and during operation can be set.
The delay at start-up only applies to unit start-up and not compressor
power-on.
High condensing pressure from pressure switch
The high condensing pressure alarm from pressure switch has the eff ect
of stopping all the compressors without observing the various times and
forcing the fans on at maximum speed, therefore when the digital input
confi gured as the high pressure switch is activated, all the compressors
on the line aff ected are stopped immediately and the fans operate at
maximum output.
This alarm features manual or automatic reset, as confi gured by the user.
The delay after which the alarm is activated can also be set.