Carel Hecu CO2 - Anti-Liquid Return MPX Valve Alarm; High Pressure Prevention Actions; MPXPRO;UltraCella Alarms Integration

49
ENG
Hecu CO
2
+0300085EN rel. 2.2 - 07.05.2019
Pressure alarms from probe
The parameters corresponding to these alarms can be set in branch C.a.e
of the main menu for suction pressure, and D.a.e for condensing pressure.
For these types of alarms, reset is automatic and the activation threshold
and diff erential can be set, as well as the type of threshold, which may be
absolute or relative to the control set point. The fi gure shows an example
of setting the threshold to relative.
Pressure
AlarmSetpoint
Relative threshold
HP
Dierential
Fig. 8.c
Note: for temperature control, the alarms from probe are managed
based on temperature even when pressure probes are fi tted.
The eff ects of the diff erent pressure alarms from probe are described
below.
Low suction pressure from probe
The low suction pressure alarm from probe has the eff ect of stopping all
the compressors without observing the times.
High suction pressure from probe
The high suction pressure alarm from probe has the eff ect of forcing
all the compressors on, ignoring the control times, but observing the
compressor protection times.
Low condensing pressure from probe
The low condensing pressure alarm from probe has the eff ect of stopping
all the fans without observing the times.
High condensing pressure from probe
The high condensing pressure alarm from probe has the eff ect of forcing
all the fans on and stopping all the compressors, ignoring the times.
8.4 Anti liquid return MPX valve alarm
For alarms that stop the compressor, if the “anti liquid return MPX valve”
function is enabled, the evaporator valves will be forced closed. This
function can be enabled on screen Cag65.
In the event of a low pressure switch alarm, the valves will not be forced
closed, so as to allow the system to restart.
Below is the list of alarms that stop the compressor and close the valve:
• High pressure
• HP prevent lock (5 attempts)
• Low SH
• High receiver pressure
• SSH-DSH
• High or low oil level
• Leak alarm
• CO2 alarm
8.5 High pressure prevention
Hecu CO2 can manage the high discharge pressure prevention actions,
involving:
• overriding the compressors and fans
Prevent by overriding the compressor and fans
The parameters corresponding to this function can be set in branch
G.c.a/G.c.b of the main menu.
The eff ect of this type of prevention action is to force on all the fans at
maximum speed and the BLDC compressor on at minimum speed.
An activation threshold can be set, which is always absolute, as well as the
deactivation diff erential.
Furthermore, the evaluation time and number of activations allowed in a
defi ned time period can also be set. If the number of activations is higher
than set, reset becomes manual.
time
dierential
Pressure
HP by pressostat
HP by probe
Prevent
Fig. 8.d
8.6 MPXPRO/UltraCella alarms
The MPXPRO and/or UltraCella alarms are sent remote to the Hecu
CO2 user interface, which also forwards them to the supervisor for
management/logging.