Table of Contents
Advertisement
Operation
4.3.1 Normal Mode
The UPS rectifier derives power from the AC mains input source and supplies DC power to the inverter, which continuously supplies
the AC load to the load. Simultaneously, the charger, which derives power from the rectifier, float, or boost, charges the associated
backup battery of the UPS.
4.3.2 Battery Mode
The UPS operates in battery mode when the battery supplies backup power to the load through the inverter. In the event of a mains
failure, the UPS automatically transfers to battery mode without interrupting the power supply to the load. When AC mains supply
is restored, the UPS automatically returns to normal mode without the need for intervention on the part of the user, and without
interrupting the power supply to the load.
Battery start function is available for switching the UPS to battery (charged) mode directly in the event of mains failure. Thus, the
battery power can be used independently to increase the UPS utility.
4.3.3 Automatic Restart Mode
The battery will become discharged following an extended AC mains failure. The inverters shut down when the battery reaches the
EOD voltage. The UPS can be programmed for automatic restart following EOD after a given variable delay time. This mode and any
delay times must be programmed by the commissioning engineer.
4.3.4 Bypass Mode
During normal operating mode, if the inverter fails, is overloaded or turned off, the static transfer switch will transfer the load from
the inverter to the bypass source without interrupting the power supply to the load. If the inverter is not synchronized with the
bypass, the static transfer switch will transfer the load from the inverter to the bypass interrupting the power supply to the load.
This is done to avoid paralleling unsynchronized AC sources. The length (time) of such interruption is programmable but typically
set to be less than 3/4 of an electrical cycle, for example, less than 15 ms (50 Hz) or less than 12.5 ms (60 Hz).
4.3.5 Maintenance Mode (Manual Bypass)
If UPS maintenance or repair is necessary, you may use the maintenance switch to transfer the load to the maintenance bypass,
without interrupting the power supply to the load. This maintenance switch is fitted in all UPS modules and rated for the full load of
one module.
4.3.6 Parallel Redundancy Mode (System Expansion)
For higher capacity, higher reliability, or both, the outputs of multiple UPS modules can be programmed for direct paralleling while
a built-in parallel controller in each UPS ensures automatic load sharing. The parallel system may include up to four UPS modules.
4.4 Battery Management (Set Up During Commissioning)
4.4.1 Normal Function
1. Constant current boost charge.
The charge current can be set up.
2. Constant voltage boost charge.
The boost charge voltage can be set up as required by the type of battery.
For VRLA batteries, the maximum boost charge voltage should not exceed 2.4 V/cell.
3. Float charge.
The float charge voltage can be set up as required by the type of battery.
For VRLA batteries, the float charge voltage should be between 2.2 V/cell and 2.3 V/cell.
4. Float charge temperature compensation.
The temperature compensation coefficient can be set up as required by the type of battery.
User Manual 10H52192UM60 - Rev. 1 - 09/2011
Note
Liebert NX
35
Advertisement
Table of Contents
