8
Operating the UPS
8.1
AC Input Mode (Normal Operation)
The following illustration shows circuit power flow when the UPS is operating normally in the AC Input Mode.
The converter of the UPS, including a boost chopper circuit, converts the AC input power into DC power. The boost
chopper circuit maintains a constant voltage and provides current limiting for charging the batteries. It also supplies a
DC voltage of the proper level to the inverter section. The inverter section generates a high quality sine wave output
voltage. The batteries are maintained in a constantly charged state when the UPS is in the "Normal Operation Mode."
Power Flow
Input
Isolating
Power
XFMR
4200FA Installation and Operation Manual
MCCB
Converter
Figure 8-1 Power flow in AC Input Mode
MBS
(Not available for LT units)
Bypass
Inverter
Charger/
Chopper
External
Batteries
Output
Power
57