Xtreme Power Conversion Corporation
R91 User’s Manual
Page 28
Uninterruptible Power Supply
Operation
Operation Modes
The UPS is a double-conversion online UPS that may operate in the following alternative modes.
Normal Mode
The rectifier / charger derives power from the AC input utility and supplies DC power to the inverter while floating
and boost charging the battery simultaneously. The inverter then converts the DC power to AC power and supplies
the load.
Battery Mode (stored energy mode)
If the AC input utility power fails, the inverter, which is operating from power supplied by the battery, supplies the
critical AC loads with power from the batteries. There is no power interruption to the critical load. The UPS will
automatically return to Normal Mode when AC input utility recovers.
Bypass Mode
If the inverter is not functioning correctly, or if an overload occurs, the static transfer switch will be activated to
transfer the load from the inverter supply to bypass supply without interruption to the critical load. In the event
that the inverter output is not synchronized with the bypass AC source, the static switch will perform a transfer of
the load from the inverter to the bypass with power interruption to the critical AC loads. This is to avoid paralleling
of unsynchronized AC sources. This interruption is programmable but typically set to be less than one electrical
cycle (less than 15ms at 50Hz or less than 13.3ms at 60Hz).
ECO Mode
When the UPS is in AC Model and the requirement to the load is not critical, the UPS can be set to ECO Mode in
order to increase the efficiency of the power supplied. In ECO Mode, the UPS works in line-interactive mode, so
the UPS will transfer to bypass utility. When the AC is out of the set window, the UPS will transfer from bypass to
inverter and supply power from the batteries, with the LCD displaying all related information.
Parallel Redundancy Mode (system expansion)
To achieve higher capacity and / or increase reliability, the output of up to four (4) UPS modules can be pro-
grammed to operate in parallel, with the built-in parallel controller in each UPS ensuring automatic load sharing.
