Liebert GXT3-5000/6000RT208
SL-23188_REV1_08-10
8
Guide Specifications
2.2
COMPONENTS
2.2.1 Input Converter
2.2.1.1 General
Incoming AC power shall be converted to regulated DC power by the input converter for supplying DC power to
the inverter. The input converter shall provide input power factor correction (PFC) and input current distortion
reduction.
2.2.1.2 AC Input Current Limit
The input shall use the power necessary to operate the load attached to the output before going to batteries. The
UPS shall not use electronic input current limiting. The UPS shall include a 2-pole switch-type 30A input
breaker.
2.2.1.3 Input Protection
The UPS shall have built-in protection against undervoltage, overcurrent and overvoltage conditions including
low-energy lightning surges, introduced on the primary AC source. The 208VAC models shall sustain input
surges without damage per criteria listed in ANSI C62.41 Cat. A.
2.2.1.4 Battery Recharge
The UPS shall contain a battery recharge rate designed to prolong battery life. The battery shall be constant
current charged to restore capacity, then shall be constant voltage charged to maintain the battery in a fully
charged state. Recharge time for the internal battery shall be 3 hours maximum to 90% capacity (full load
discharge rate). There shall be DC overvoltage protection so that if the DC voltage exceeds the pre-set limit, the
inverter shall shut down automatically and the critical load shall be transferred to internal bypass.
2.2.2 Inverters
2.2.2.1 General
The UPS inverters shall be of a pulse-width-modulated (PWM), IGBT design capable of providing the specified
AC output. The inverters shall convert DC power from the input rectifier output or the battery into precise
sinewave AC power for supporting the critical AC load.
2.2.2.2 Overload
The inverter shall be capable of supplying current and voltage for overloads exceeding 100% and up to 201% of
full load current. A visual indicator and audible alarm shall indicate overload operation. For greater currents or
longer time duration, the inverter shall have electronic current-limiting protection on the output to prevent
damage to components. The inverter shall be self-protecting against any magnitude of connected output overload.
Inverter control logic shall sense and disconnect the inverter from the critical AC load without the requirement to
clear protective devices.
2.2.2.3 Inverter DC Protection
The inverter shall be protected by the following DC shutdown levels:
DC Overvoltage Shutdown
DC Undervoltage Shutdown (End of Discharge)
2.2.2.4 Output Frequency
An oscillator shall control the output frequency of the UPS. The inverter shall maintain the output frequency to
±0.1Hz of nominal frequency during Battery mode, Frequency Converter mode or when otherwise not
synchronized to the utility/mains source.
2.2.2.5 Output Protection
The UPS inverter shall employ electronic current limiting circuitry for protection during Normal mode and
battery operation and shall employ input circuit breaker protection during Bypass mode operation.
