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ENG
Heos +0300078EN - rel. 1.6 - 23.11.2017
Compression ratio control
When normal operating conditions mean the compressor works at
a compression ratio below the limit allowed by the envelope, two
procedures can be activated:
• MOP procedure using EEV: the valve closes, increasing the pressure
diff erential and consequently the compression ratio
• compressor acceleration: increasing the speed, the compressor increases
the pressure diff erential and consequently the compression ratio.
Compressor shutdown for pump down
The pump down procedure is used to improve compressor restarts
without the risk of liquid on the suction side. In this case, the following
actions are carried out:
• the EEV closes;
• the compressor continues operating and speeds up (or down), after
the time cPL from when the function starts, based on the distance
from the threshold, and stops when the pressure reaches cPt, or when
the maximum time cPM has elapsed;
• during the procedure, the LP alarm is disabled.
6.6.2 ON/OFF compressor control
In the branch used to confi gure the type of compressor, ON/OFF
compressors can also be selected; in this case, control is based on
temperature too.
The PID remain parameters the same (kp and ti), with the same meaning
for both inverter-controlled and on/off compressors.
The compressor is started when the request exceeds 98% and stops
when it falls below 2%..
In multi-evaporator confi gurations, the suction valves close when the
compressor is OFF.
Pressure control with ON/OFF compressor
If a multi-evaporator system is confi gured, control can be performed
based on pressure rather than temperature. In this case, the control
sequence is as follows:
• the compressor is started (based on pressure) by one of thermostats
on the cabinet/showcase, with active envelope control;
• the individual EEV valves strive to maintain the desired controlled
temperature inside the cabinet/showcase, as set on screen Ca02.
6.6.3 ON/OFF control with multi compressors
The confi guration for on/off compressor control (up to 5 compressors in
5 circuits) also allows the selection of propane compressors. In this case,
there are no analogue inputs for managing the high and low pressure,
but rather only the possibility to manage a digital alarm (for example,
thermal overload) selected from the digital or/and universal channels (on
screens Bac15 to Bac19); alarm discharge temperature management by
probes selectable (Baa17 ... 21) with threshold setting on the mask Dad07.
The position of the digital outputs is selected on screens Dad15 to Dad19.
On screen Dab13, a delay time can be selected for activation (or
deactivation) between one compressor and the next.
6.6.4 Propane (R290) inverter compressor control
Propane compressors can be selected for the specifi c part numbers listed
below.
P/N Description
UP2AH610302SK Heos for propane cabinet - 230 Vac power supply
UP2BH610302SK Heos for propane cabinet - 24 V power supply
UP2AH630302SK Heos for propane cabinet with door - 230 Vac power supply
UP2BH630302SK Heos for propane cabinet with door - 230 Vac power supply
Tab. 6.a
As for the HFC models, the compressor is selected during the wizard to
be completed when commissioning the unit
(see Commissioning). Before selecting the installed compressor, make
sure that the Power+ inverter is connected to the Heos controller.
On screen Dab01, the compressors available for the application can be
selected; currently this is:
• SIAM SPB 172
Other models can be implemented on request by contacting Carel HQ
directly.
In the same way as for the other types of compressor, the thermodynamic
and timing parameters are an integral part of the Heos controller software, so
as to control the compressor while verifying that its operating conditions are
always within the limits allowed by the manufacturer.
The electrical parameters are written into the Power+ inverter fi rmware,
allowing sensorless control to manage the compressor eff ectively.
Furthermore, when selecting the compressor, all the thermodynamic and
timing parameters are automatically confi gured.
Therefore, no other parameters need to be set before starting the compressor.
All of the compressor management functions (envelope, on/off ramps,
equalisation, oil recovery, discharge temperature...) are the same as for HFC
compressors.
Note: for this type of compressor, multi-evaporator management is
NOT available, rather the compressor can only be combined with a single
evaporator.
The pressure probes must be suitable for use with propane (e.g.
SPKT***P**) ,
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