Liebert PowerSure PSI 1000 - 3000VA 60 Hz 120V - Manual (Page 13)

Major Components
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3.3 Automatic Voltage Regulator
The Automatic Voltage Regulator (AVR) protects connected equipment from power spikes, sags and
other abnormalities by raising (boosting) or lowering (bucking) the output voltage as needed. This
keeps the UPS output voltage within the connected equipment’s tolerance and accommodates wide
utility voltage fluctuations without utilizing the batteries.
3.4 Battery Charger
In Normal mode, the Battery Charger converts utility AC power into regulated DC power to float
charge the battery. It is continuously charging the battery whenever the UPS is plugged into a power
outlet and utility power is within acceptable limits - even if the UPS is turned Off.
3.5 Battery
The PowerSure PSI utilizes valve-regulated, nonspillable, lead acid batteries. To maintain battery
design life, operate the UPS in an ambient temperature of 68°F to 77°F (20°C to 25°C). Optional
external battery cabinets are available to extend battery run times.
3.6 Inverter—1000/1440 Models Only
In battery mode operation, the inverter utilizes the DC output of the battery and inverts it into pre-
cise, regulated, sinewave AC power.
3.7 DC-to-DC Converter—1920/2200/3000 Models Only
The DC-to-DC Converter utilizes energy from the battery system and raises the DC voltage to the
optimum operating voltage for the Bi-Directional Converter. This allows the Bi-Directional Converter
to operate continuously at its optimum efficiency and voltage, thus increasing reliability.
3.8 Bi-Directional Converter—1920/2200/3000 Models Only
In normal operation, the Bi-Directional Converter changes utility AC power into regulated DC power
to “float charge” the battery system. This converter is continuously charging the battery whenever the
UPS is plugged into a power outlet and utility power is within acceptable limits—even if the UPS is
turned Off. When utility power fails, the Bi-Directional Converter draws energy from the battery
through the DC-to-DC Converter and inverts it into a regulated sinewave supplying power to con-
nected equipment.