Specifications

Liebert Nfinity UPS Guide Specification
4kVA –20kVA (208/120 or 240/120) 4/03 Rev 2
SL-23956
5
C. Input Protection
The UPS has built-in protection against undervoltage, overcurrent, and overvoltage
conditions including low-energy surges introduced on the primary AC source and the bypass
source. The UPS can sustain input surges without damage per criteria listed in IEEE C62.41,
Category A & B. The UPS cabinet contains an input breaker sized to supply full 20kVA rated
load and to recharge the battery at the same time.
D. Battery Recharge
To prolong battery life, the UPS contains temperature-compensated battery charging. When
an equal number of power modules and battery modules are installed the battery charger is
able to recharge the internal batteries to 90% charge in six hours at nominal input voltage and
nominal ambient temperature.
E. Charger Output Filter
The battery charger is a DC power supply to minimize ripple current into the battery.
2.2.2 Inverter
A. General
The inverter converts DC power from the input converter output, or the battery, into precise
regulated sine wave AC power for supporting the critical AC load.
B. Overload
The inverter is capable of supplying current and voltage for overloads exceeding 100% and
up to 200% of full load current. A visual indicator and audible alarm indicates overload
operation. For greater currents or longer time duration, the inverter has electronic current-
limiting protection to prevent damage to components. The inverter is self-protecting against
any magnitude of connected output overload. Inverter control logic senses and disconnects
the inverter from the critical AC load without the requirement to clear protective fuses. The
load will be transferred to bypass when any of the above conditions are exceeded.
C. Maximum Load Alarm
The user can set the alarm point to a value less than 100% rating such that the UPS will alarm
before an overload condition or loss of redundancy is reached.
D. Output Frequency
The output frequency of the inverter is controlled by an oscillator. The oscillator will hold the
inverter output frequency to +/- 0.5% for steady state and transient conditions. The inverter
tracks the bypass continuously, providing the bypass source maintains a frequency within the
user-selected synchronization range. If the bypass source fails to remain within the selected
range, the inverter will revert to the internal oscillator.
E. Output Protection
The UPS inverter employs electronic current limiting.
F. Battery over Discharge Protection
To prevent battery damage from over discharging, the UPS control logic controls the
shutdown voltage set point. This point is dependent on the rate of discharge.
2.2.3 Display and Controls
A. General
The front panel will consist of multiple status LEDs, switches, and a four line by twenty
character LCD display for additional alarm/configuration information. All mimic display
LED‟s are green in color and indicate the following:
AC Input
On Battery
Load On/Off
On Inverter
On Bypass