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System Overview
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5.1.15 Ventilation and Cooling
The Liebert FS stator and power electronics are liquid cooled with a liquid-to-air radiator. The radia-
tor within the Liebert FS package is designed for natural and forced air-cooling. Air inlets are pro-
vided from the bottom front of the Liebert FS enclosure. Air exhaust is from the top of the unit. Air
filters are provided as an option. A minimum 12" clearance overhead is required for the exhaust air-
flow.
The Liebert FS was designed with reliability in mind, the radiator is positioned to take advantage of
natural cooling and forced-air is only used when there is an elevated temperature. This also applies to
the circulating pump for the coolant, which is a highly reliable magnetically coupled centrifugal pump
that is powered with a brushless DC motor. This pump operates only when there is an elevated tem-
perature within the stator or the PCM, this extends the life of the pump to the point that it will con-
tinue to operate over the life of the unit.
5.2 List of System User-Configurable Parameters
In order to support a wide set of UPS integrations, the Liebert FS can be configured using the follow-
ing operating parameters: See 6.0 - Operation for more information on these parameters and
instructions on system setup and entering parameters to system.
Charge Voltage (Vcharge)
Vcharge is the voltage threshold above which the Liebert FS begins to charge/recharge.
Vcharge must be set at least 10VDC greater than Vreg.
• Range: 360-600VDC
• Default setting: 530VDC
Regulation Voltage (Vreg)
• Vreg is the voltage setpoint at which the Liebert FS will regulate the DC bus voltage in Discharge
Mode
• Vreg must be set at least 10 VDC less than Vcharge.
• Range: 350-590VDC
• Default setting: 520VDC
Maximum Charge Current (Max Charge Current)
• Max Charge Current is the Maximum Current the Liebert FS is allowed to draw from the UPS
DC bus.
• Range—1-50A (typical operation requires a minimum of 3A or 5A)
• Default setting—20 A
Charge Conductance (Charge Amps/Volts)
Charge amps/volts is used to set the Liebert FS charging current drawn from the UPS DC bus based
upon how much the UPS DC bus voltage is above Vcharge and so without exceeding the Max Charge
Current.
• Range—0.1-10 A/V
• Default setting: 2 A/V
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