Emerson Liebert iCOM Manual De Usuario

Depending on the product control design, there may be an internal minimum speed, as defined by 

that specific product operation. Minimum fan speeds are defined below.

• Direct expansion units with pressure transducers 70%
• Chilled water units 60% (available option to 25%)
• Direct expansion units with low-pressure switches limited to 80%.
• Direct expansion units with standard scroll or 2-step semi-hermetic compressor(s) limited to 

100%.
Contact your local Emerson dealer for more information if fan speed minimum settings must be 

lowered from the values above.

Additional fan speed configuration parameters include a fan speed filter and fan speed reposition 

delay timer. These parameters allow fine tuning the fan speed control and, except for setting to 

Manual, are applicable to any other operation mode set in the VSD fan speed setting.

• The fan speed filter allows the fan to respond at a different rate depending on the location of the 

control point within the proportional band.
Example: When the controlled temperature is near the setpoint or at conditions where the 

proportional band output is decreasing and approaching 0%, the fan speed change rates are 

proportionally decreased to avoid overshooting the controlled temperature. However, when the 

temperature rises above the setpoint or at conditions where the proportional band output is 

increasing, the fan speed change rates are proportionally increased.

• The fan speed reposition delay timer setting in the Liebert iCOM menu may be changed to 

improve the fan operation stability if it is oscillating. The delay timer holds back the fan output 

change until each delay period is reached if fan speed is decreasing. If fan speed is increasing, 

then the delay timer has no effect.

An option in Service Menus > Setpoints > FC / AirEco Ramp Up w/CFC, allows the fan to ramp with 

the economizer. The default value is No, allowing the fan ramp independently of free-cooling. When 

set to Yes, the control will compare the call for fan to the free-cooling request. This will provide the 

most capacity from the Liebert Air Economizer and will help in holding off the mechanical cooling 

(second stage). When the economizer is not available, the fan will ramp based on the fan control 

sensor deviation from setpoint.