Liebert iCOM Microprocessor TM-10098 - Manual (Page 19)

iCOM
Controls Training and Service Manual
Optional Dual Compressor Digital Scroll Operation
2 compressor operation
C1
C2
Start/ stop
PWM
20
35
70
100
35 70 0%
50
25
On
Off
10 20
Off
On
pressor ON Switch 1 com
st
Switch 2
nd
compressor ON
1 compressor operation
In the chart above we are defining the Digital Compressor start and stop at the
capacity need and how the compressors load and unload with the PWM from the
controller and the unit setting for temperature control.
Note that the Digital Scroll will run continuously while the head is raised and
lowered as the need for cooling is required from 10% to 100% and vise versa.
Optional Glycool (Econ-O-Cycle) Cooling
When supplied with the Glycool option, the basic unit is supplied with an additional
coil, piping, valve and a Glycol Fluid Sensor (AQ), which is mounted to the unit
supply fluid line and serves as control interface in determining the system
operation. Selection of the glycool or compressorized operation is controlled by
microprocessor using this aquastat to sense the glycol temperature.
The Glycool (Econ-O-Cycle) Cooling program establishes two distinct control
bands for cooling control operation. The first band controls the operation of the
chilled glycol valve and the second controls the operation of the compressors,
either 2-stage or 4-stage.
The microprocessor checks the return air temperature and the entering glycol fluid
temperature to determine a cooling capacity. In order to reduce compressor
cycling and to prevent chilled glycol valve hunting, Glycool (Econ-o-Cycle) cooling
capacity does not become available until the entering chilled glycol fluid
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