Liebert® NXL™ UPS
for a 250-400kVA
Single-Module Uninterruptible Power System
These specifications describe requirements for an Uninterruptible Power System (UPS). The UPS shall automatically maintain AC power within specified tolerances to the critical load, without interruption, during failure or deterioration of the normal power source.
The manufacturer shall design and furnish all materials and equipment to be fully compatible with electrical, environmental and space conditions at the site. It shall include all equipment to properly interface the AC power source to the intended load and be designed for unattended operation.
The UPS and all associated equipment and components shall be manufactured in accordance with the following applicable standards:
UL Standard 1778, 4th Edition
CSA 22.2, No. 107.1
National Electrical Code (NFPA 70)
The UPS shall be UL listed per UL Standard 1778, 4th Edition, Uninterruptible Power Supplies and shall be CSA certified.
The UPS shall comply with FCC Rules and Regulations, Part 15, Subclass B, Class A.
The Quality System for the engineering and manufacturing facility shall be certified to conform to Quality System Standard ISO 9001 for the design and manufacture of power protection systems for computers and other sensitive electronics.
The UPS shall be sized to provide a minimum of ____ kVA and a minimum of ____ kW output.
The UPS shall be able to power at full rated output kW loads with power factor between 0.9 lagging and 0.95 leading.
Load voltage and bypass line voltage shall be 480VAC, three-phase, 3-wire or 4-wire. Input voltage shall be 480VAC, three-phase, 3-wire.
The battery shall support the UPS at 100% rated kW load for at least _____ minutes at 77°F (25°C) at startup.
The UPS shall have a 6-pulse solid state rectifier.
An input filter with automatic disconnect for input power factor control shall be provided.
The UPS shall be equipped with an output isolation transformer.
Modes of Operation
The UPS shall operate as an on-line reverse transfer system in the following modes:
Normal: The critical AC load is continuously powered by the UPS inverter. The rectifier/ charger derives power from the utility AC source and supplies DC power to the inverter, while simultaneously float charging the battery.
Economy: The critical AC load is continuously powered by the bypass with the inverter available to power the load if the bypass source voltage or frequency exceeds adjustable parameters of power quality.
Emergency: Upon failure of utility AC power, the critical AC load is powered by the inverter which, without any switching, obtains its power from the battery plant. There shall be no interruption in power to the critical load upon failure or restoration of the utility AC source.
Recharge: Upon restoration of the utility AC source, the rectifier/charger powers the inverter and simultaneously recharges the battery. This shall be an automatic function and shall cause no interruption to the critical AC load.
Bypass: If the UPS must be taken out of service for maintenance or repair, the static transfer switch shall transfer the load to the bypass source. The transfer process shall cause no interruption in power to the critical AC load.
Off-Battery: If the battery only is taken out of service for maintenance, it is disconnected from the rectifier/charger and inverter by means of an external disconnect circuit breaker. The UPS shall continue to function and meet all of the specified steady-state performance criteria, except for the power outage backup time capability.
The solid-state power components, magnetics, electronic devices, and overcurrent protection devices shall operate within the manufacturer’s recommended temperature when the UPS is operating at 100% critical load and maintain battery charging with the following conditions occurring simultaneously.
Any altitude, within the specified operating range up to 5000 ft. (1500m) elevation
Any ambient temperature, within the specified operating range of 32°F to 104°F (0°C to 40°C)
Any one failed fan
Any input voltage within the specified range, +10% to -15% of nominal
Air filters 50% blocked
Voltage Range: +10%, -30% of nominal (no battery charging below -15%)
Frequency Range: ±5Hz
Rectifier Walk-In: 0% to 100% of full rated load over 1 - 30 seconds (adjustable)
Sub-Cycle Magnetizing Inrush: Not to exceed 5 times normal full load input current
Power Factor: Minimum 0.92 lagging at full load with nominal input voltage
2-Step Rectifier Input Current Limit:
Step 1 - Independently adjustable 25-125% of normal full load input current
Step 2 - Independently adjustable 25-125% for on-generator operation
2-Step Battery Charge Current Limit:
Step 1 - Independently adjustable 0-20% of maximum battery discharge current
Step 2 - Independently adjustable 0-20% of maximum battery discharge current
Current Distortion: Less than 10% THD at full load input current
Surge Protection: Sustains input surges without damage per criteria listed in ANSI C62.41, category B3 (6kV)
Withstand Rating: Units shall carry a 65kAIC standard withstand rating, 100kAIC rating shall be available optional. All withstand ratings shall be UL tested and certified.
Load Rating: 104% continuous load rating at 104°F (40°C) for any combination of linear and non-linear loads
Voltage Regulation: ±1% for balanced load, ±2% for 50% unbalanced load for both line-to-line and line-to-neutral unbalances
Voltage Adjustment Range: ±5% manually
Automatic Line Drop Compensation: Adjustable 0 to +5% of nominal voltage
Frequency Regulation: 0.1%
Efficiency: Defined as output kW/input kW at rated lagging load power factor. Not less than 93% from 50 to 100% load for 480V versions.
Balanced loads 120° ±0.5°
Unbalanced loads 120° ±1°
Voltage Transients (Average of all Three Phases):
100% Load Step ±5%
Loss of/return to AC input power ±1%
Output Voltage Transients
Voltage transients shall be limited to a maximum deviation from nominal system output volts of plus or minus 5% with recovery to within 1% of the nominal output voltage within one electrical cycle (16 milliseconds) for each of the following conditions. Limits shall apply to any UPS load within the UPS rating, and frequency shall be maintained at 60 Hz ± 0.1 Hz. The system shall not transfer to bypass under these conditions (except item 3).
100% load step
Loss or return of AC input power, momentary sags, surges or spikes on the input to the UPS (all three phases or single phase)
Uninterrupted transfer of the critical load to and from the UPS output and bypass power line (manually initiated or automatic)
Voltage Harmonic Distortion:
Maximum 2% RMS total (linear load)
Maximum 2.5% RMS total for up to 100% non-linear load, per IEC 62040-3
Overload at full Output Voltage with ±1% voltage regulation:
110% of full load for 60 minutes
125% of full load for 10 minutes
150% of full load for a minimum of 60 seconds
Current Limit: 200% full load current
Inverter only: 200% of normal full load current for 200 milliseconds, or 155% of normal full load current for 5 seconds (when bypass is not available).
Bypass available: 1000% for 200 milliseconds in inverter pulse-parallel operation when bypass is available.
The AC output neutral shall be electrically isolated from the UPS chassis. The UPS chassis shall have an equipment ground terminal. A terminal for bonding the system neutral to facility service entrance ground (customer-provided cable) shall be provided.