Liebert UPS Systems PSI XR - Manual (Page 21)

Operational Modes
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5.0 O
PERATIONAL
M
ODES
5.1 Normal Mode
When the UPS is in Normal Mode, the Normal Mode Indicator illuminates green.
5.2 Buck/Boost Mode
The Automatic Voltage Regulator (AVR) circuitry compensates for fluctuations in utility power, such
as voltage surges and sags. When the Liebert PSI XR detects an abnormality, it raises the undervolt-
age (boost) or lowers the overvoltage (buck) as needed. The AVR operates automatically and main-
tains the output voltage to the connected equipment, without utilizing the batteries.
LED 1 flashes green and LED 9 illuminates steady green when the UPS is in Boost Mode. LED 2
flashes green and LED 9 illuminates steady green when the UPS is in Buck Mode (see 9.0 - Trouble-
shooting for details).
5.3 Battery Mode
The UPS switches to Battery Mode in the event of an extreme input voltage/frequency condition or
utility failure.
When the UPS is in Battery Mode, the Battery Indicator illuminates amber and an alarm sounds at
two-second intervals. As capacity decreases, fewer indicators remain illuminated.
When a Low Battery condition occurs, the Battery Indicator flashes amber and an alarm sounds at
one-second intervals. Refer to Table 8 for approximate battery run times.
5.4 Battery Recharge Operation
Once utility power is restored, the UPS resumes normal operation and the Battery Charger begins
recharging the batteries.