Emerson Liebert XDP, User Manual

Page: 49 / 80

Liebert iCOM Control—Firmware Version XP1.00.010.STD
43
Min Room Temperature Setpoint —Sets the minimum room temperature the unit will attempt to
maintain. If the temperature falls below this point, unit will raise the refrigerant temperature to
reduce the amount of cooling. Adjustable from 50 to 80°F (10.0 to 26.7°C), the factory default setting
is 60°F (15.6°C).
Temperature Control Type —Selects the type of control the system will use to activate cooling. The
Liebert iCOM control has three temperature control types: Proportional, PI and Intelligent. The
factory default is Intelligent.
Proportional —If Proportional Control is selected, the percent cooling requirement is
determined by the difference between the air temperature sensor reading and the temperature
setpoint. As the air temperature rises above the temperature setpoint, the percent cooling
required increases proportionally (from 0 to 100%) over half the programmable temperature
proportional band. The percent heating requirement (0 to 100%) is determined the same way
when the air temperature falls below the setpoint.
PI —If PI Control is selected, the percent cooling requirement is calculated by adding together two
individual terms, proportional and integral. The proportional term is calculated in a manner
similar to the previously described Proportional control. The integral term (sometimes called
reset action) is calculated by measuring how much and for how long the air temperature has been
above or below the setpoint. If the actual air temperature is above the setpoint, the percent
requirement is slowly but continuously increased until the total is sufficient to bring the return
room air back to the setpoint.
Intelligent —If Intelligent Control is selected, the air temperature is controlled at or near the
setpoint. The percent temperature adjustment required is calculated based on logic that is
programmed into the control. These rules simulate the actions that would be taken by a human
operator manually controlling the system.
Temperature Proportional Band —Adjusts the activation points of compressors or rate of change
based on the actual sensor values deviation from setpoint. The smaller this number the faster the
compressors and valve(s) will increase capacity. Too small of a number may cause the unit to short
cycle the compressors or excessively reposition the valve. This parameter is adjustable from 1.8 to
54.0°F (1.0 to 30.0°C). The factory default setting is 7.0°F (3.9°C).
Temperature Integration Time —Temperature integration takes into consideration the amount of
time the actual temperature has deviated from the setpoint. The larger this deviation is the longer
the unit will wait before corrective action is taken to achieve the setpoint. This parameter is
adjustable from 0 to 15 minutes. The factory default is 0.
Temperature Derivative Time —Monitors the rate of change and will reduce or increase the
amount of corrective action based on the actual temperature increasing or decreasing toward the
temperature setpoint. This parameter is adjustable from 0-900 seconds. The factory default is 0.
Dewpoint Margin —Selects the difference between the room dew point and the refrigerant
temperature control point. This parameter is adjustable from 4.0 to 10.0°F (2.2 to 6.0°C). The factory
default setting is 4.0°F (2.2°C).
Minimum Control Point —Sets the minimum supply refrigerant temperature the Liebert XDP will
maintain. This parameter is adjustable from 40 to 80°F (4.4 to 27.0°C). The factory default is 55°F
(12.8°C).
Min Percent Cooling Setpoint —Selects the lowest percent call for cooling during normal
operations. Whenever the unit is not in startup mode or OFF, the percent call for cooling cannot go
below this value. The parameter is adjustable from 5 to 30%. The factory default is 15%.
NOTE
This is not a true room temperature setpoint. The Liebert XDP has no heaters; it will try to cool
as much as possible. If the Liebert XDP is able to cool the room to this setpoint, it will reduce its
cooling action to try to keep the room temperature at or above this setpoint.