General Compressor Operation; Figure 19 Energy Efficiency-No Bypass Air, Ec Fan Damper - Emerson Liebert iCOM Manual

Figure 19 Energy efficiency—No bypass air, EC fan damper
3.1.3

General Compressor Operation

Low-Pressure Time Delay
When the compressor starts, the low-pressure input is ignored for a selected period of time based on
the setting of the Low Pressure Alarm Delay (Service Menu, Options Setup). This time is usually set
to 3 minutes on air-cooled units, and to 0 or 1 minute on water cooled units. When this time is
expired, a second timer starts to operate if the low-pressure input is active. This second timer is active
during normal compressor operation to avoid compressor trips due to bubbles in the refrigerant or
other influences creating short trips of the low-pressure device. The low-pressure device input is
ignored if the compressor is not operating.
NOTE
Low-pressure condition could be read through contacts or through pressure transducers with
threshold setting.
Advanced DX Freeze Protection
Applying fan speed to direct expansion systems generates the issue of how to avoid freezing
condensate on the coil when the unit operates below 100% fan speed. Liebert iCOM's advanced freeze
protection provides the ability to predict freeze conditions and correct this condition automatically by
adjusting the fan speed and compressor capacity.
Compressor Type Support
• Digital scroll (all sizes)
• Tandem Scroll
Freeze Protection
• Fan and compressor will override sensors when freezing is detected
• Fan ramps up first, then compressor unloads
Pump Down Operation
The Liebert DSE is not equipped with pump down mode due to the microchannel condenser.
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Operation
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Liebert iCOM for Liebert DSE
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