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Application guidelines
7
FRCC.PC.014.A4.22
Variable speed compressors
Variable speed technology offers more flexi-
bility in compressor selection than fixed speed
compressors. Selection of the right variable
speed compressor size can be done by different
methods:
1. Maximum cooling capacity: Select a compres-
sor size which achieves the peak load system
cooling capacity demand at its maximum speed.
2. Nominal cooling capacity: Select a compressor
size which achieves the nominal system cooling
capacity at a rotational speed of 3600 - 4500 rpm
(60-75 Hz).
3. Best Seasonal Efficiency Ratio: Select a
compressor size which achieves the minimum
system cooling demand at its minimum speed.
Ensure that the compressor is able to cover the
peak load system cooling capacity. This selection
makes the compressor to run for a maximum of
time at part load where the system efficiency is
highest.
Performance tables at 3 speeds can be found in
following pages. Detailed performances can be
found in datasheets and in selection program.
Compressor
size
Different frequency converter variants are avail-
able according to:
Main supply voltage
IP class (CDS302 drives are available in IP20 or
IP55 housings)
3. RFI class (Radio Frequency Interference) H2 or
H3
4. Local Control Panel (LCP) provided or not
5. Printed Circuit Board (PCB) coated or not
coated.
When the compressor size and mains voltage
have been defined with above selection criteria,
the code number tables from section “Ordering
information and packaging” give the appropriate
frequency converter sizes and up to 16 corre-
sponding code numbers for each compressor
model.
Frequency converter
variants
Compressor and frequency
converter combinations