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|Liebert® NX™ UPS|
Three-Phase Uninterruptible Power System
This specification defines the electrical and mechanical characteristics and requirements for a continuous-duty three-phase, solid-state uninterruptible power system (UPS). The UPS shall provide high-quality AC power for sensitive electronic equipment loads.
The UPS shall be designed in accordance with the applicable sections of the current revision of the following documents. Where a conflict arises between these documents and statements made herein, the statements in this specification shall govern.
The UPS shall be UL and cUL listed per UL Standard 1778.
Rectifier Input: (_____) volts, three-phase, (_____)-wire-plus-ground
Bypass Input (for dual-input modules): (_____) volts, three-phase, (_____)-wire-plus-ground
Output: (_____) volts, three-phase, 4-wire-plus-ground
Current Sharing: When multiple UPS modules are connected in parallel and powering a common load, each UPS module output current will not differ by more than 5% of the rated full load current of one UPS module.
The UPS shall be designed to operate as an on-line, double-conversion, reverse-transfer system in the following modes:
±1% three-phase RMS average for a balanced three-phase load for the combined variation effects of input voltage, connected load, battery voltage, ambient temperature and load power factor
±2% three-phase RMS average for a 100% unbalanced load for the combined variation effects of input voltage, connected load, battery voltage, ambient temperature and load power factor
±0.25% for paralleled units
Fixed maximum of 0.2Hz/sec for paralleled units
±0.5 degree for balanced load
±1.0 degrees for 100% unbalanced load
1% total harmonic distortion (THD) for linear loads
<4% THD for 100% nonlinear loads (3:1 crest factor) without kVA/kW derating
110% for 1 hour
125% for 10 minutes
150% for 1 minute
100% load step ±4.0%
Loss or return of AC input power ±1.0%
Manual transfer of 100% load ±3.0%
The UPS shall be able to withstand the following environmental conditions without damage or degradation of operating characteristics:
UPS Module: 32°F to 104°F (0°C to 40°C)
Battery: 77°F ±9°F (25°C ±5°C)
UPS Module: -13°F to 158°F (-25°C to 70°C)
Battery: -4°F to 92°F (-20°C to 33°C)
0 to 95%, non-condensing
Operating: to 3300 ft. (1000m) above mean sea level. Derated for higher altitude applications.
Storage/Transport: to 40,000 ft. (12,200m) above mean sea level.
Noise generated by the UPS under any condition of normal operation shall not exceed 54 dBA measured 1 meter from the surface of the UPS.
Submittals with the proposal shall include:
Submittals upon UPS delivery shall include a complete set of submittal drawings and one (1) set of instruction manuals that shall include a functional description of the equipment with block diagrams, safety precautions, instructions, step-by-step operating procedures and routine maintenance guidelines, including illustrations.
The UPS manufacturer shall warrant the UPS module against defects in materials and workmanship for 12 months after initial startup or 18 months after ship date, whichever period expires first.
The battery manufacturer’s standard warranty shall be passed through to the end user.
A minimum of 20 years’ experience in the design, manufacture and testing of solid-state UPS systems is required. The system shall be designed and manufactured according to world-class quality standards. The manufacturer shall be ISO 9001:2000 certified.
Before shipment, the manufacturer shall fully and completely test the system to assure compliance with the specification.
All materials of the UPS shall be new, of current manufacture and high grade and shall not have been in prior service except as required during factory testing. All active electronic devices shall be solid-state. All power semi-conductors shall be sealed. Control logic and fuses shall be physically isolated from power train components to ensure operator safety and protection from heat. All electronic components shall be accessible from the front without removing sub-assemblies for service access.
Wiring practices, materials and coding shall be in accordance with the requirements of the National Electrical Code, OSHA and applicable local codes and standards. All bolted connections of busbars, lugs and cables shall be in accordance with requirements of the National Electrical Code and other applicable standards. All electrical power connections shall be torqued to the required value and marked with a visual indicator.
Provisions shall be made in the cabinets to permit installation of input, output and external control cabling, using raceway or conduit. Provision shall be made for top and bottom access to input, output, bypass and DC connections. In conformance with NEC, connection cabinets shall provide for adequate wire bend radius. All copper busbars for customer power connections shall be tin plated for connection integrity.
The UPS shall be in NEMA Type 1 enclosures, designed for floor mounting. The UPS shall be structurally adequate and have provisions for hoisting, jacking and forklift handling.
Cooling of the UPS shall be by forced air using a redundant fan configuration. Fan power shall be provided by the UPS.
The thermal design, along with all thermal and ambient sensors, shall be coordinated with the protective devices before excessive component or internal cabinet temperatures are exceeded. Air filters shall be located at the point of air inlet and be changeable.
The AC output neutral shall be electrically isolated from the UPS chassis. The UPS chassis shall have an equipment ground terminal. Provisions for local bonding shall be provided.
The term rectifier/charger shall denote the solid-state equipment and controls necessary to convert AC to regulated DC for input to the inverter and for charging the battery.
The rectifier/charger unit shall be provided with AC input current limiting whereby the maximum input current shall be limited to 125% of the full input current rating. The rectifier/charger shall operate at a reduced current limit mode whenever the critical load is powered from the UPS static bypass circuit such that the maximum UPS input current will not exceed 125% of full load input current. In addition, the rectifier/charger shall have a battery current limit, adjustable from 0 to 25% of the full load input current.
The rectifier/charger shall have an output filter to minimize ripple current into the battery. The AC ripple voltage of the rectifier DC output shall not exceed 1% RMS of the float voltage. The filter shall be adequate to ensure that the DC output of the rectifier/charger will meet the input requirements of the inverter without the battery connected.
Upon restoration of utility AC power, after a utility AC power outage and prior to a UPS automatic end-of-discharge shutdown, the rectifier/charger shall automatically restart, walk-in and gradually assume the inverter and battery recharge loads.
In addition to supplying power for the inverter load, the rectifier/charger shall be capable of producing battery charging current sufficient to replace 95% of the battery discharge power within ten (10) times the discharge time. After the battery is recharged, the rectifier/charger shall maintain the battery at full charge until the next emergency operation.
There shall be DC overvoltage protection so that if the DC voltage rises to the preset limit, the UPS is to shut down automatically and initiate an uninterrupted load transfer to the static bypass line.
The term inverter shall denote the equipment and controls to convert DC from the rectifier/charger or battery to precise AC to power the load. The inverter shall be solid-state, capable of providing rated output power, and for increased performance the inverter shall be a pulse-width-modulated design and utilize insulated gate bipolar transistors (IGBTs).
The inverter shall be capable of supplying current and voltage for overloads exceeding 100%. The inverter is to provide 150% of full load for 1 minute, 125% of full load for 10 minutes and 110% of full load for 1 hour. A status indicator and audible alarm shall indicate overload operation. The UPS shall transfer the load to bypass when overload capacity is exceeded.
The inverter shall be capable of supplying an overload current of 150% of its full-load rating for one minute. For greater currents or longer time duration, the inverter shall have electronic current-limiting protection to prevent damage to components. The critical load will be transferred to the static bypass automatically and uninterrupted. 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 fuses.
The output voltage shall be maintained to within ±4% with a 0-to-100% step load change or a 100%-to-0 step load change. The output voltage shall recover to within 1% of nominal voltage within 1 cycle.
Total harmonic distortion in the output voltage will not exceed 1% for 0% to 100% linear loads.
Total harmonic distortion in the output voltage will not exceed 4% for 0% to 100% non-linear loads.
Total harmonic distortion in the output voltage will not exceed 5% for 0% to 100% non-linear, unbalanced loads.
Electronic controls shall be provided to regulate each phase so that an unbalanced loading will not cause the output voltage to go outside the specified voltage unbalance or phase displacement. With 100% load on one phase and 0% load on the other two phases or 100% load on two phases and 0% load on the other phase, the voltage balance is to be within 2% and the phase displacement is to be 120 degrees within ±1 degree.
Power semiconductors in the inverter unit shall be fused with fast-acting fuses, so that loss of any one power semiconductor will not cause cascading failures.
For rapid removal of the inverter from the critical load, the inverter control electronics shall instantaneously turn off the inverter transistors. Simultaneously, the static transfer switch shall be turned on to maintain continuous power to the critical load.
The inverter shall be protected by the following disconnect levels:
The inverter shall use a software control to adjust the output voltage from ±5% of the nominal value.
The output frequency of the inverter shall be controlled by a high-speed DSP capable of holding the inverter output frequency to within ±0.05% during steady state and transient conditions. Total deviation from the rated frequency, including short time fluctuations and drift, shall not exceed 0.05%.
The UPS shall be provided with a microprocessor-based unit status display and controls section designed for convenient and reliable user operation. A graphical display shall be used to show a single-line diagram of the UPS and shall be provided as part of the monitoring and controls sections of the UPS. All operator controls and monitors shall be located on the front of the UPS cabinet. The monitoring functions such as metering, status and alarms shall be displayed on the graphical display. Additional features of the monitoring system shall include:
The following parameters shall be displayed:
The following alarm messages shall be displayed:
An audible alarm shall be provided and activated by any of the above alarm conditions.
The following UPS status messages shall be displayed:
UPS startup, shutdown and maintenance bypass operations shall be accomplished through the front-panel pushbutton controls. Menu-driven user prompts shall be provided to guide the operator through system operation without the use of additional manuals. Pushbuttons shall be provided to display the status of the UPS and to test and reset visual and audible alarms. A mimic screen shall be available on the LCD screen to depict a single-line diagram of the UPS with switch positions and power flow.
The UPS shall be provided with a menu-driven On-Line Battery Test feature. The test shall ensure the capability of the battery to supply power to the inverter while the load is supplied power in the normal mode.
A static transfer switch and bypass circuit shall be provided as an integral part of the UPS. The static switch shall be a naturally commutated high-speed static (SCR-type) device rated to conduct full load current continuously. The switch shall have an overload rating to clear a 20-ampere load branch circuit breaker.
The static transfer switch control logic shall contain an automatic transfer control circuit that senses the status of the inverter logic signals and operating and alarm conditions. This control circuit shall provide an uninterrupted transfer of the load to an alternate bypass source, without exceeding the transient limits specified herein, when an overload or malfunction occurs within the UPS or for bypassing the UPS for maintenance.
The transfer control logic shall automatically turn on the static transfer switch, transferring the critical AC load to the bypass source, after the transfer logic senses any of the following conditions:
The transfer control logic shall inhibit an automatic transfer of the critical load to the bypass source if any of the following conditions are present:
Retransfer of the critical AC load from the bypass source to the inverter output shall be automatically initiated unless inhibited by manual control. The transfer control logic shall inhibit an automatic retransfer of the critical load to the inverter if one of the following conditions exists:
A manually operated maintenance bypass switch shall be incorporated into the UPS cabinet to directly connect the critical load to the bypass AC input power source, bypassing the rectifier/charger, inverter and static transfer switch.
All energized terminals shall be shielded to ensure that maintenance personnel do not inadvertently come in contact with energized parts or terminals. A means to de-energize the static switch shall be provided when the UPS is in the maintenance bypass mode of operation.
With the critical load powered from the maintenance bypass circuit, it shall be possible to check out the operation of the rectifier/charger, inverter, battery and static transfer switch. When the application calls for the Maintenance Bypass Switch to be bolted to the UPS cabinet, the interconnecting cables are to be provided, precut and pre-lugged.
The battery cabinet shall include ten (10) year design life, valve-regulated, lead-acid battery cells housed in a separate cabinet that matches the UPS cabinet styling to form an integral system lineup. All battery cell inter-connects shall utilize bolted connections, and all batteries shall include copper, inserted terminal posts allowing connector torque of 110 in-lb (12.4 Nm). Battery cells shall be mounted on slide-out trays for ease of maintenance. A battery disconnect circuit breaker shall be included for isolation of the battery pack from the UPS module. Casters and leveling feet shall also be provided with the battery power pack cabinet for ease of installation. When the application calls for the battery cabinet to be bolted to the UPS cabinet, an interconnecting cable kit will be available, precut and pre-lugged.
Provides communication outputs to indicate a change of status of the UPS. Outputs are provided for:
A matching external maintenance bypass cabinet shall be provided to enable the UPS module to be completely isolated from the electrical system while the critical load is powered through the external maintenance bypass line. This optional cabinet shall provide make-before-break operation for transfers to and from the external maintenance bypass line with a single rotary switch. The following components shall be standard: input and output circuit breakers, single rotary switch with auxiliary contacts, inter-cabinet wiring, casters and leveling feet. Optional voltage matching transformers and isolation transformers are to be offered. This matching cabinet shall bolt to the side of the UPS module with a barrier shield to separate the two cabinets. Only front access shall be required for installation and service.
Five sets of isolated contacts shall be provided to indicate a change of status of the UPS. Contacts are provided for:
A battery circuit breaker shall be provided to isolate the battery from the UPS. This breaker shall be in a separate wall-mounted NEMA-1 enclosure. The battery breaker provides a manual disconnecting means, short-circuit protection and overcurrent protection for the battery system. When opened, there shall be no battery voltage in the UPS enclosure. The UPS shall be automatically disconnected from the battery when the battery reaches the minimum discharge voltage level.
The remote alarm panel shall have LED alarm lights. An audible alarm shall sound upon any alarm condition. The surface- or flush-mounted NEMA 1 enclosed panel shall indicate:
A matching external paralleling cabinet shall enable multiple UPS modules to be paralleled for capacity or redundancy. A maximum of three (3) modules may be paralleled for capacity (3X) and an optional fourth module may be added for redundancy. Paralleling cabinets shall not require a centralized static switch or control function. Each UPS shall contain a bypass circuit that transfers to and from bypass in synchronization with other UPS connected to the paralleled bus.
The following inspections and test procedures shall be performed by factory-trained field service personnel during the UPS startup.
The UPS manufacturer shall directly employ a nationwide service organization consisting of factory-trained field service personnel dedicated to the startup and maintenance of UPS and power equipment.
The manufacturer shall provide a national dispatch center to coordinate field service personnel schedules. One toll-free number shall reach a qualified support person 24 hours a day, 7 days a week, 365 days a year. If emergency service is required, on-site response time shall be four hours or less within 150 miles of an Emerson Network Power Liebert Services center.
Two local customer engineers shall be assigned to the site with a regional office as a backup. Escalation procedures shall be in place to notify Power Technical Support if a site is not functioning within 24 hours.
Parts shall be available through an extensive network to ensure round-the-clock parts availability throughout the country.
Spare parts shall be stocked by local field service personnel with backup available from national parts center and the manufacturing location. A national parts center Customer Support Parts Coordinator shall be on call 24 hours a day, 7 days a week, 365 days a year for immediate parts availability.
A complete offering of preventive and full-service maintenance contracts for both the UPS system and battery system shall be available.
The UPS manufacturer shall provide as an option an automated site-monitoring service. This service shall be staffed by a qualified support person 24 hours a day, 7 days a week, 365 days a year. At the detection of an alarm within the UPS, the controls shall initiate communications with the monitoring service. The monitoring service shall be capable of interpreting the communicated alarms to allow dispatch of a service engineer.
SL-25225_REV1_08-10 Guide Specifications