Carel Hecu handleiding
Handleiding
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Hecu +0300023EN rel. 1.2 - 14.12.2021
Superheat control
The EEV valve controls subcooled refrigerant fl ow out of the condenser
and into the heat exchanger. Minimum subcooling must be guaranteed
at the EEV valve inlet to avoid fl ash gas.
Vapor
injection
valve
U2 U1
Plate
Exchanger
Liquid from condenser
Vapor temperature injection
into cmp leaving H/X
Vapor temperature
entering H/X
Subcooler liquid leaving H/X
to system EEV
PT
Fig. 6.w
This function is only available for low temperature systems. Injection
superheat is calculated as the diff erence between saturated injection
temperature (calculated by converting the pressure at the end of the
heat exchanger) and the superheated gas temperature (measured by the
temperature probe at the heat exchanger outlet).
The expansion valve must be controlled with extreme precision, based
on a superheat set point defi ned by the user. These parameters can be
set on screens Fdb09 and Fdb10.
Notice: a backup compressor can also be used for low temperature
applications. In this case, in addition to the vapour injection valve that
injects directly into the compressor, two solenoid valves will also need to
be installed to divert the vapour fl ow into the operating compressor.
Discharge temperature control
When discharge temperature exceeds the limit value, the system
operates in high discharge temperature mode, and the valve is opened
more intensely. The higher the discharge temperature above a certain
threshold, the more the electronic valve opens. Hecu defi nes the
discharge temperature set point in accordance with the operating limits
defi ned by the envelope.
Valve operation is represented in Figure 6.t. Minimum valve opening
corresponds to the value read at the instant when reaching the minimum
discharge temperature, while maximum opening is settable on
screen
Fdb04, as are the minimum and maximum discharge temperature
thresholds.
6.10 Generic functions
Hecu can use the free inputs/outputs and certain internal variables for a
number of generic functions.
The following generic functions are available for each board:
• 5 stages
• 2 modulation functions
• 2 alarms
Each function can be enabled/disabled by digital input and on the
user interface. The generic functions can be enabled and the related
parameters set in main menu branch E.f. To be able to use the free inputs,
these fi rst need to be confi gured as generic probes A to E (analogue
inputs) and general inputs F to J (digital inputs), consequently a maximum
of fi ve analogue inputs and fi ve digital inputs can be used.
After having confi gured the generic probes, the associated variables can
be used as control variables, and the digital inputs to enable the functions.
As well as the generic probes and inputs, other internal variables in the
Hecu software can be used, depending on system confi guration.
Examples:
for analogue variables:
• Suction pressure
• Condensing pressure
• Saturated suction temperature
• Saturated condensing temperature
• Suction temperature
• Discharge temperature
• % of compressors active
• % of fans active
• Superheat
• Subcooling
• Liquid temperature
• % compressor request
• % fan request
for digital variables:
• High suction pressure alarm
• Low suction pressure alarm
• High condensing pressure alarm
• Heartbeat
Each generic function can be assigned a unit of measure and a description.
Below are descriptions of how the three types of generic functions work.
Stages
Hecu can manage up to fi ve stage functions, with either direct or reverse
operation. In both cases, a set point and a diff erential can be defi ned;
operation of the corresponding output is shown in the fi gure below, for
both two cases:
Regulation
variable
Setpoint
Diff. Diff.
Direct stage
Regulation
variable
Setpoint
Diff. Diff.
Reverse stage
Fig. 6.x
If a variable has been set to enable the function, the output connected to
the stage will be active when the enabling variable is active.
For each stage, there is a high alarm threshold and a low alarm threshold,
both absolute values. For each alarm, the activation delay and priority can
be confi gured.
Modulation
Hecu can manage two modulation functions, with either direct or reverse
operation. In both cases, a set point and a diff erential can be defi ned;
operation of the corresponding output is shown in the fi gure for direct
operation, with the cut-off function also enabled:
Bekijk gratis de handleiding van Carel Hecu, stel vragen en lees de antwoorden op veelvoorkomende problemen, of gebruik onze assistent om sneller informatie in de handleiding te vinden of uitleg te krijgen over specifieke functies.
Productinformatie
| Merk | Carel |
| Model | Hecu |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 10743 MB |
