Powerware 9330 - Manual (Page 79)

6--5 Powerware 9330 (10 kVA--40 kVA) Installation and Operation
164201300 REV. G 061502
The battery charger derives its input from the unregulated DC output of the rectifier
and provides regulated DC voltage and charge current to the battery. The battery
charge condition is monitored by the UPS and reported by status indicators
located on the LCD monitor panel. The battery is always connected to the UPS
and ready to support the inverter should the utility input become unavailable.
The DC boost converter derives power from the unregulated DC rectifier and
produces an elevated and stable DC voltage and current source for the inverter.
The boost converter also establishes the systems output neutral for supporting
single phase AC loads from any phase of the inverter output. The output neutral of
the system is connected with the required neutral supplied at the utility bypass
input and should never be bonded to ground at the modules output.
The inverter produces a three phase AC output to a customers load without the use
of a transformer. The inverter derives power from the boost converters regulated
DC and utilizes IGBT devices and pulse---width modulation (PWM) to produce a
regulated and filtered AC output. The AC output of the inverter is delivered to the
system output through the output contactor (K3).
If the utility AC power is interrupted or is out of specification, the UPS automatically
switches to Battery mode to support the critical load with no interruption. When
utility power returns, the UPS returns to Normal mode.
If the UPS becomes overloaded or unavailable, the UPS switches to Bypass mode.
The UPS automatically returns to Normal mode when the overload condition is
cleared and system operation is restored within specified limits.
If the UPS suffers an internal failure, it switches automatically to Bypass mode and
remains in that mode until the failure is corrected and the UPS is back in service.