Emerson Liebert iCOM, Manual

Page: 51 / 172

Operation
43 Liebert
®
iCOM
®
for Liebert DSE
™
3.6 Supply Control
The supply temperature sensor should be placed in an area that is influenced only by the unit it is
connected to. The supply sensor must be located 5-15 ft. (1.5-4.5m) from the unit to provide an
accurate reading for the control.
Figure 30 Placing the supply air temperature sensor
The Supply Air sensor can be used to control or reference the discharge air temperature of the cooling
unit. This sensor can be added to existing Liebert iCOMs by purchasing the supply sensor and wiring
harness. The supply air sensor must be connected to P13, Pins 1 and 2. Contact your local Emerson
representative for pricing and installation.
When the supply sensor is set to Control, the unit will control the amount of cooling / heating being
provided based on maintaining the discharge air temperature. The return air sensor may still be used
to control fan, humidity or as temperature/humidity reference of the room.
• Supply Limit: The supply limit can be enabled only when the unit’s temperature control sensor is
set to either Remote Sensor or Return Sensor. The unit may be set up with the supply air sensor
to maintain a minimum air temperature under a raised floor to help prevent condensation. To
avoid supply temperatures that are too low, the Supply Limit can influence the opening of
three-point or analog actuators, or compressor capacity. The control compares the deviation from
the return air setpoint and the supply limit setpoint and calculates the output to the actuator
from the smaller deviation.
When the supply air sensor is set up for Temperature control, additional Supply Air configuration
parameters (valve pulse, cooling filters and return compensation) can be used to further enhance the
supply air control.
• The cooling filter timer can be adjusted to prevent oscillating around the supply setpoint and still
allow for rapid cooling capacity adjustments to compensate for heat load changes. Contact your
local Liebert service personnel for adjustments.
• Return Compensation begins to increase the supply air setpoint when the return air temperature
decreases below the return air setpoint.
Example
Setting the return compensation value in the Service > Setpoints menu to 5°F (2.7°C) will increase
the supply setpoint from 50°F to 55°F (10°C to12.8°C) when the return temperature is at the low
limit of the proportional band.
Temperature
Sensor
5 to 15feet
(1.5 to 4.5m)
Internal Temperature
and Humidity Sensor
Return
Air
Supply Air
Liebert
Cooling Unit