User Manual 10H52188UM60 - Rev. 2 - 09/2012
9
Liebert NX
Product Introduction
1.4
Operating Principle
The operating principle of the UPS is shown in Figure 1-6.
Figure 1-6 UPS operating principle
1. The UPS is composed of mains input (mains and bypass), I/O filter, rectifier/PFC, charger, inverter, bypass, battery, DSP
controller, System Control Power and UPS output.
2. Under normal mains supply conditions, the rectifier switches on and the charger supplies recharge power to the battery.
Before the UPS is switched on, the load is connected directly to the mains supply via the Bypass. Once the UPS has been
switched on, the mains input supplies DC power to the inverter via the rectifier/PFC section. The inverter then converts DC
power into pure sine wave AC power, and supplies AC power to the load through the electronic transfer switch.
3. If the mains supply is outside the normal operating limits, the rectifier/PFC circuit boosts the battery voltage and supplies it
to the inverter. The inverter then converts it into pure sine wave AC power, and supplies AC power to the load through the
electronic transfer switch.
4. After the mains returns to normal state, the UPS will automatically transfer from battery mode to Normal mode, the mains
supplies DC power to the inverter through the rectifier/PFC circuit, and then the electronic transfer switch supplies AC power
to the load.
Bypass input
Mains input
Output
Input filter
Bypass
Inverter
Output filter
Rectifier/PFC
Auxiliary
power
Charger
DSP
controller
Battery
