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7.0 OPERATION
7.1 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 tech-
nology 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 44, 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 batter-
ies—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 44 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