Figure 6.18 Setpoints
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.
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.
Vertiv | Liebert® XDC™ User Manual | 81
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