Powerware 9390 UPS 100160 kVA - Manual (Page 55)

UNDERSTANDING UPS OPERATION
EATON Powerware ® 9390 UPS (20–80 kVA) Installation and Operation Manual S 164201603 Rev 2 www.powerware.com 7-3
7.1.2 Normal Mode – RT
Figure 7‐2 shows the path of electrical power through the UPS system when the UPS
is operating in Normal mode.
Static
Switch
K5
Rectifier Inverter
K1 K3
Battery
Converter
Battery
Battery
Breaker
Main Power Flow
Trickle Current
Energized
De-Energized
Closed
Open
Breakers Contactors
Static
Switch
K5
Rectifier Inverter
K1 K3
Battery
Converter
Battery
Battery
Breaker
Main Power Flow
Trickle Current
Energized
De-Energized
Closed
Open
Breakers Contactors
Figure 7‐2. Path of Current Through the UPS in Normal Mode – RT
During normal UPS operation, power for the system is derived from a utility input
source through the rectifier input contactor K1. The front panel displays “Normal,”
indicating the incoming power is within voltage and frequency acceptance windows.
Three-phase AC input power is converted to DC using IGBT devices to produce a
regulated DC voltage to the inverter. The battery is charged directly from the
regulated rectifier output through a buck or boost DC converter, depending on
whether the system is 208V, 380V, 400V, 415V, or 480V and the size of the battery
string attached to the unit.
The battery converter derives its input from the regulated DC output of the rectifier
and provides either a boosted or bucked regulated DC voltage charge current to the
battery. The UPS monitors the battery charge condition and reports the status on the
control panel. The battery is always connected to the UPS and ready to support the
inverter should the utility input become unavailable.