Operation
21
Liebert
®
iCOM
®
for Liebert DSE
™
Variable Speed Fans—EC or Variable Frequency Drives
The Liebert iCOM control can adjust airflow manually through a BMS or dynamically using locally
installed temperature sensors. Parameters related to VSD fan speed setting can be found in the
Service Menu > Setpoints submenu on page 5 of 8. This menu allows the cooling unit's fan motor
speed to be configured and adjusted for a variety of applications by selecting which sensor controls the
fan speed.
Four fan control modes are available: Manual, Supply, Return and Remote. All units ship from the
factory with the temperature control and fan speed control sensor set to the Return Air Sensor.
•
Manual Control
: When set to Manual, the speed of the fan motor follows user input as set either
at the Liebert iCOM display or remotely through an optional Liebert IntelliSlot
®
card. See
External Communication—Building Management Systems, Liebert SiteScan
for more
information regarding Liebert iCOM remote monitoring options.
Before the building management system can control the fan speed, two parameters in the control
must be set. S146 “Fan Control Sensor” must read
Manual
and line S164 “Allow BMS to change
Fanspeed” must be changed to
YES
at the Liebert iCOM. Both parameters are found in Service
Menus > Service Setpoints.
Figure 17 Setting manual fan control and changing the setpoint
Fan speed may be written through the building management system to line S152. The user can
change this locally. However, if the speed is set by the BMS, it will override the local setting.
•
Supply, Return and Remote Control
: These selections allow fan modulation using an
equipped return, supply or remote sensor; see
for applicable control sensor combinations.
If the fan control and the temperature control sensor have the same sensor selected, the control is
considered coupled. If different sensors are selected, the control is considered decoupled. When
operating the fan in coupled mode, the fan speed follows the call for cooling to reach the
temperature setpoint. When the fans are operating in decoupled mode, the fans are ramped
following the fan control band to achieve the fan setpoint.
Table 5
Controlling sensor settings
S103 Temperature Control Sensor
Supply
Remote Sensor
Return
S125 Fan
Control Sensor
Supply
Factory Default
(Coupled)
N/A
N/A
Remote Sensor
Recommended
(Decoupled)
(Coupled)
N/A
Return
(Decoupled)
(Decoupled)
(Coupled)
These commands
permit setting manual
fan control and
changing the setpoint.
Options for this are
Return, Remote,
Supply and Manual.
Summary of Contents for Liebert iCOM
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