Liebert PSITM - Manual (Page 21)

Modes of Operation
17
7.0 M
ODES OF
O
PERATION
7.1 Normal Mode
During Normal mode operation, the PowerSure PSI supplies conditioned, computer-grade power to
the connected equipment: mains power passes through the TVSS circuitry and the EMI/RFI filters
and then through the Inverter (1000VA & 1440VA) / Bi-Directional Converter (2200VA & 3000VA) to
connected equipment.
When the UPS is in Normal mode, the AC Input Indicator illuminates green. The UPS display in
Figure 13 shows the UPS operating in Normal mode with 26% - 50% load connected to the output.
Figure 13 Normal mode operation with 26-50% load
The PowerSure PSI continuously monitors the batteries to maintain them in a fully charged state.
The battery charger operates whenever AC power is present, even if the UPS is switched Off. By
default, the UPS is set to perform an automatic battery test after it has been operating continuously
for two (2) weeks. The automatic battery test can be disabled via MultiLink.
7.2 Buck/Boost Mode
The Automatic Voltage Regulator (AVR) circuitry compensates for fluctuations in mains power, such
as voltage surges and sags. When the PowerSure PSI 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 critical equipment, without utilizing the batteries.
The Buck/Boost Indicator flashes green when the UPS is operating in Buck mode and illuminates
green when the UPS is operating in Boost mode (see 11.0 - Troubleshooting for details).
Figure 14 Buck/Boost mode operation with 51-75% load and 21-40% battery capacity
Mains power present ...
... and within operational limits
Indicator shows
UPS in Boost Mode
(solid green)