Operation
47
Liebert
®
iCOM
®
for Liebert DSE
™
When supply air compensation has been invoked, it will be indicated on the unit view by a small
downward-pointing arrow. See
Figure 36 Supply Compensation in Unit View
During normal operation, as the rack temperature increases above the fan temperature setpoint, the
fan speed will increase until it reaches 100% speed. 100% fan speed is achieved once the controlling
temperature reaches a value equal to 100% of the fan control band, or S116 Fan Se 1/2(S150
Fan Deadband) + 1/2(S149 Fan Temp Prop Band).
How many degrees the supply temperature will be lowered while supply compensation is invoked
depends on how many degrees the fan controlling temperature has exceeded the control band
compared to S116 Supply Compensation Value.
Example
: With a Fan Setpoint of 70ºF and Proportional band of 10ºF, 0ºF deadband, the fan
speed is 100% when the rack temperature is 75ºF. If S116 Supply Compensation value = 10ºF, the
supply air temperature will lower one degree for every degree the rack temperature increases
outside the fan control band. This means if the air temperature setpoint is 65ºF, and the rack
temperature increase to 77ºF, the supply air temperature will lower to 63ºF.
Supply Compensation
: This selection provides the ability to enable both supply and
return compensation settings as described above.
Figure 37 Supply/return compensation
Supply
Compensation
in Unit View
76
78
74
73
72
100%
Compensation
50%
Compensation
Blower at 100%
of Capacity
Blower Proportional Band
Fan Speed Proportional
Band 8°F (4°C)
Supply Temperature Setpoint
will be decreased by the Supply
Compensation band when the
fan speed proportional band
has doubled
After the blower reaches 100
percent and the temperature
continues to increase, the
supply temperature setpoint will
be decreased proportionally
Supply
Compensation
Band 8°F (4°C)
Summary of Contents for Liebert iCOM
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