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9.0 OPERATION
9.1 General Description
Liebert’s NX provides continuous, high-quality AC power to your business-critical equipment, such as
telecommunications and data processing equipment. The Liebert
®
NX
™
UPS supplies power that is
free of the disturbances and variations in voltage and frequency common to utility power, which is
subject to brownouts, blackouts, surges and sags.
The Liebert NX utilizes the latest in high-frequency, double-conversion pulse width modulation
technology and fully digital controls to enhance its reliability and increase the ease of use.
Specifically, the Liebert NX 480V utilizes soft-switching technology to greatly enhance efficiency.
As shown in Figure 51, the AC utility source is input at CB1 and the rectifier converts the AC utility
into DC power. The inverter converts that DC power from the utility—or DC power from the
batteries—into AC power for the load. The batteries power the load through the inverter in the event
of a power failure. The utility source can also power the load through the static bypass.
If maintenance or repair of the UPS is necessary, the load can be switched without interruption in
service to the maintenance bypass.
Figure 51 Single module block diagram (dual input configuration)
3-Phase
3W + Gnd
3-Phase
3W + Gnd
AC Input
AC Output
3-Phase
3W + Gnd
Battery Cabinet
2W + Gnd
UPS Cabinet
Converter
InverterRectifier
Static Bypass
Internal Maintenance Bypass