Emerson Liebert iCOM Manual De Usuario

The Liebert iCOM can operate mechanical dampers using digital outputs on the main control board to 

prevent airflow from entering a standby unit. Dampers can be controlled with or without a damper 

end switch. If a damper end switch is used, the Liebert iCOM will monitor damper operation and 

annunciate a Damper Failure event if the damper is not able to open. Damper opening and closing 

will be displayed in the unit status portion of the unit view screen.
The integral relay on the control board is rated up to 27VAC and 2A. An additional contactor or 

control relay with power supply will be required if the application exceeds this limit.

The user can connect h up to six power meters per unit. Power meters are factory-programmed to 

monitor power characteristics for either individual component or total units. These meters allow the 

user to monitor connection status, input undervoltage, input RMS voltage leg-to-leg and leg-to-

ground, input current for each phase, energy consumption in kilowatt hours and instantaneous power 

in watts. The intelligent meters allow the user to monitor power consumption before and after making 

changes to the Liebert iCOM. This allows the user to determine the most efficient control setup for 

their data center.

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. Exception: Pump Down (see Pump Down).

The advanced low-pressure routine is automatically used when a unit is equipped with the Liebert 

iCOM, unloading compressors (Tandem Scroll, Digital Scroll, and 4-Step), low-pressure transducers, 

and variable fan speed (VFD or EC fans). The low-pressure routine monitors the low-pressure 

transducers and interacts with the fan and compressor to prevent the unit’s coil from freezing.
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.

• Digital scroll (all sizes)
• Tandem scroll
• Four-step (all sizes)
• No standard scroll support

• Fan and compressor will override sensors when freezing is detected
• Fan ramps up first, then compressor unloads