1 Scope

NOTE This standard covers static (solid-state) uninterruptible power supply systems consisting of a rectifier/charger, an inverter, an energy storage subsystem (battery or equivalent), an internal static bypass, and the associated controls, monitoring, and communications, furnished to supply conditioned, continuous AC power to critical loads. (1.1)

NOTE The work includes the UPS unit or units, the energy storage subsystem and its enclosure, the external maintenance bypass, the input and output distribution to the extent furnished with the UPS, and the field connection, testing, and commissioning of the system. (1.2)

NOTE A UPS conditions the incoming power and rides through a source interruption from stored energy; it is a ride-through and power-quality device, not a long-duration standby source, and is conventionally paired with a generator where outages may exceed the battery autonomy. (1.3)

1.4 Equipment and installation shall comply with UL 1778 for the UPS unit and with NFPA 70 for the installation.

1.5 Where the UPS serves an information technology equipment room or area governed by NFPA 70 Article 645, the UPS, its battery, and its disconnecting and emergency-power-off provisions shall comply with that Article.

NOTE Topology, capacity, autonomy, and redundancy shall be selected together as a system; a decision in any one of these areas constrains the others. (1.6)

1.7.1 The generator or alternate source that backs the UPS for outages longer than the battery autonomy shall be coordinated with GeneratorsEngine GeneratorsResolves to the current edition.sync/generators.

1.7.2 The transfer of the UPS input between the normal source and the alternate source shall be coordinated with Automatic Transfer SwitchesAutomatic Transfer SwitchesResolves to the current edition.sync/automatic-transfer-switches.

1.7.3 Surge protection ahead of the UPS input shall be coordinated with Surge Protective DevicesSurge Protective DevicesResolves to the current edition.sync/surge-protective-devices.

1.7.4 Grounding and bonding of the UPS, its output neutral where the output is a separately derived system, and the battery enclosure shall be coordinated with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

1.7.5 Input and output feeders, battery conductors, and their ampacity, voltage drop, and derating shall be coordinated with Conductors And CablesConductors and CablesResolves to the current edition.sync/conductors-and-cables.

1.7.6 The room or space that houses the UPS and its battery, including clearances, ventilation, and environmental control, shall be coordinated with Electrical RoomsElectrical RoomsResolves to the current edition.sync/electrical-rooms.

1.7.7 A DC control-power battery plant for switchgear is a different system from a UPS and shall be specified to DC Battery SystemsDC Battery SystemsResolves to the current edition.sync/dc-battery-systems.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of the following standards and codes.

2.2 Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

2.3 Standards List

Standard	Title
UL 1778	Uninterruptible Power Systems
UL 9540	Energy Storage Systems and Equipment
UL 9540A	Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems
UL 1973	Batteries for Use in Stationary, Vehicle Auxiliary Power and Light Electric Rail Applications
NEMA PE 1	Uninterruptible Power Systems (UPS) — Specification and Performance Verification
IEC 62040-3	Uninterruptible Power Systems (UPS) — Method of Specifying the Performance and Test Requirements
IEEE 1184	Guide for Batteries for Uninterruptible Power Supply Systems
IEEE 1100	Recommended Practice for Powering and Grounding Electronic Equipment (Emerald Book)
IEEE 519	Recommended Practice and Requirements for Harmonic Control in Electric Power Systems
NFPA 70	National Electrical Code (Article 480 — Storage Batteries; Article 645 — Information Technology Equipment)
NFPA 70E	Standard for Electrical Safety in the Workplace
NFPA 75	Standard for the Fire Protection of Information Technology Equipment
NFPA 855	Standard for the Installation of Stationary Energy Storage Systems
IBC	International Building Code
IFC	International Fire Code
ASCE 7	Minimum Design Loads and Associated Criteria for Buildings and Other Structures
ICC ES AC156	Acceptance Criteria for Seismic Certification by Shake-Table Testing of Nonstructural Components
ENERGY STAR	ENERGY STAR Program Requirements for Uninterruptible Power Supplies
ANSI/NETA ATS	Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems

NOTE UL 1778 is the safety listing standard for the UPS unit; NEMA PE 1 and IEC 62040-3 govern how performance is specified and verified, including the topology classification; and IEEE 1184 governs the selection and sizing of the battery. (2.4)

NOTE A lead-acid or nickel-cadmium battery that serves only a UPS within the scope of UL 1778 is generally exempt from UL 9540, while a lithium-ion energy storage subsystem brings UL 9540, UL 9540A, and NFPA 855 into scope. (2.5)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for the Engineer's review prior to fabrication and procurement:

Product data for the UPS module(s), the energy storage subsystem, the external maintenance bypass, and any input/output transformers or filters, identifying the topology classification, the kVA and kW ratings, the input and output voltages and configurations, and the efficiency at rated load
Battery (or energy storage) runtime sizing calculation per IEEE 1184, showing the design load in watts, the inverter efficiency, the end-of-discharge voltage, the design autonomy, the aging and temperature derating, and the resulting battery configuration
The output ratings and waveform performance, including the rated load power factor, the permitted crest factor, the steady-state and transient output voltage regulation, and the output voltage total harmonic distortion into a nonlinear reference load
The input performance, including the input current total harmonic distortion (THDi), the input power factor, and the inrush and walk-in characteristics, with any input filter required to meet them
A system one-line diagram showing the normal and bypass sources, the rectifier, inverter, static bypass, external maintenance bypass, energy storage, output distribution, and the make-before-break bypass arrangement
The redundancy configuration and, for parallel or dual-bus systems, the paralleling and load-sharing scheme and the behavior on loss of one module
Heat rejection (kW or BTU/h) at rated load and at the expected operating load, and the airflow and clearance requirements, for coordination with the room cooling
Communications and monitoring data, including the protocols provided (SNMP, Modbus, BACnet), the available dry-contact points, and the emergency-power-off (EPO) interface
For a lithium-ion energy storage subsystem, the UL 9540 listing and the UL 9540A test report, and the NFPA 855 compliance documentation including clearances and any required fire detection or suppression
Seismic certification documentation for the UPS and battery enclosures where required by the applicable building code
Manufacturer's installation instructions, including conductor terminations, grounding, and battery handling

Action Submittals Requiredcheckbox

☑ Product data (topology, kVA/kW, voltages, efficiency)

☑ Battery/energy storage runtime sizing calculation (IEEE 1184)

☑ Output ratings and waveform performance (PF, crest factor, regulation, THD)

☑ Input performance (THDi, power factor, inrush/walk-in, filter)

☑ System one-line diagram (sources, static and maintenance bypass)

☑ Redundancy configuration and paralleling/load-sharing scheme

☑ Heat rejection, airflow, and clearance data

☑ Communications and monitoring data (SNMP/Modbus/BACnet, contacts, EPO)

☐ Lithium-ion: UL 9540 listing, UL 9540A report, NFPA 855 compliance

☐ Seismic certification for UPS and battery enclosures

☑ Manufacturer installation instructions

3.1.2 Installation and procurement of any portion of the UPS system shall not proceed until the corresponding submittals are reviewed and returned.

3.1.3 The submitted runtime calculation shall be at the actual design load, not at the UPS nameplate rating, because most UPS units are loaded below nameplate and the runtime varies strongly with load.

3.2 Closeout Submittals

3.2.1 The Contractor shall provide the following at substantial completion before the UPS system is accepted into service:

Operation and maintenance manuals for the UPS, the energy storage subsystem, and the maintenance bypass
Factory test reports for the UPS unit, including the burn-in and the functional verification of transfer and bypass
Field commissioning report, including the load (bank) test results, the battery discharge/runtime verification, the transfer and bypass verification, and the alarm and communications verification
As-built one-line diagram and as-built settings, including output voltage, transfer thresholds, and battery parameters
A record of the commissioned battery configuration, the measured float voltage, and, for lithium-ion, the battery management system baseline
A written sequence of operation describing normal, battery, static-bypass, maintenance-bypass, and EPO states and the transitions between them
Warranty documentation for the UPS and for the energy storage subsystem
A recommended preventive maintenance schedule and the battery replacement interval

Closeout Submittals Requiredcheckbox

☑ Operation and maintenance manuals (UPS, energy storage, bypass)

☑ Factory test reports (burn-in, transfer/bypass functional)

☑ Field commissioning report (load test, runtime, transfer/bypass, alarms)

☑ As-built one-line and as-built settings

☑ Commissioned battery configuration and baseline record

☑ Written sequence of operation (normal/battery/bypass/EPO)

☑ Warranty documentation (UPS and energy storage)

☑ Preventive maintenance schedule and battery replacement interval

4 Quality Assurance

4.1 Manufacturer Qualifications

4.1.1 The UPS shall be the product of a manufacturer regularly engaged in the production of static UPS systems of the specified rating and topology, with a documented history of the proposed product in comparable service.

4.1.2 The manufacturer shall maintain a factory service organization and a parts supply capable of supporting the system over its service life within the response time required by the Owner.

4.2 Listing and Labeling

4.2.1 The UPS unit shall be listed and labeled to UL 1778 by a Nationally Recognized Testing Laboratory.

4.2.2 A lithium-ion energy storage subsystem shall be listed to UL 9540 and its cells or modules shall be evaluated to UL 1973, and the system shall have a UL 9540A thermal-runaway test report acceptable to the AHJ.

4.2.3 The external maintenance bypass and any furnished distribution shall be listed for the application and the available fault current at the point of connection.

NOTE A UPS that is not listed to UL 1778 shall not be installed. (4.2.4)

4.3 Performance Verification Basis

4.3.1 The UPS performance shall be specified and verified in accordance with NEMA PE 1 or IEC 62040-3, so that ratings submitted by different manufacturers are stated on a common basis.

4.3.2 Efficiency and energy consumption shall be reported in accordance with the ENERGY STAR or U.S. Department of Energy test method so that quoted efficiencies are comparable.

5 Environmental and Service Conditions

5.1 The UPS and its energy storage subsystem shall be suitable for the temperature, humidity, altitude, and air quality of the space in which they are installed, derated where required by the manufacturer's published data.

5.2 Operating Temperature

5.2.1 The design operating temperature of the UPS location shall be as indicated in the datasheet.

Design Operating Temperature (UPS Location)select

20°C–25°C (68°F–77°F) — conditioned IT/electrical room

0°C–40°C (32°F–104°F) — general indoor

Manufacturer's full rated range — site specific

5.2.2 The UPS shall be installed in a space maintained within the manufacturer's rated operating temperature range.

5.2.3 Battery service life is strongly temperature-dependent, and the battery space shall be maintained near the battery's reference temperature to achieve the published life.

NOTE VRLA battery life roughly halves for each sustained rise of about 10°C above the reference temperature near 25°C, so allowing the battery space to run warm to save cooling energy trades a small operating saving for a large premature-replacement cost. (5.2.4)

5.3 Altitude

5.3.1 The installation altitude shall be as indicated in the datasheet.

Installation Altitudeselect

0–3300 ft (0–1000 m), no derating

3300–6600 ft (1000–2000 m), manufacturer derating

Above 6600 ft (2000 m), site-specific derating

5.3.2 The UPS continuous rating shall be confirmed for the installation altitude, because reduced air density above approximately 3300 ft (1000 m) reduces the convective cooling of the power semiconductors and requires derating.

5.4 Seismic Requirements

5.4.1 The seismic certification basis shall be as indicated in the datasheet.

Seismic Certificationselect

Not required

IBC/ASCE 7 — Importance Factor 1.0

IBC/ASCE 7 — Importance Factor 1.5 (essential facility)

OSHPD/HCAI pre-approval required (California healthcare)

Per drawings — structural drawings (deferred by default)

NOTE The Seismic Design Category and Importance Factor are established by the project's structural design; the electrical scope adopts them rather than setting them. (5.4.2)

5.4.3 Where required by the applicable building code, the UPS and the battery enclosure shall be seismically certified by shake-table testing per ICC ES AC156 or by analysis per ASCE 7.

5.4.4 Site-specific anchorage of the UPS and the battery enclosure shall be designed by the Engineer of Record and shall be as shown on the equipment anchorage details.

6 Topology Selection

NOTE IEC 62040-3 classifies static UPS by the dependence of the output on the input: VFI (output independent of input voltage and frequency), VI (output voltage independent of input, frequency dependent), and VFD (output dependent on input voltage and frequency). (6.1)

6.2 Topology Classification

6.2.1 The UPS topology shall be as indicated in the datasheet.

UPS Topology (IEC 62040-3 Classification)radio

● Double-conversion / online (VFI)

○ Line-interactive (VI)

○ Standby / offline (VFD)

6.2.2 The topology shall be selected for the sensitivity of the connected load and the quality of the source.

NOTE A double-conversion (VFI) UPS continuously rectifies the input to DC and re-inverts to AC, so the load is always supplied by the inverter and is fully isolated from input voltage and frequency disturbances, with zero transfer time on loss of input; it is the default for IT, data center, and mission-critical loads. (6.2.3)

NOTE A line-interactive (VI) UPS supplies the load from the conditioned utility through an inverter/converter that regulates voltage and charges the battery, transferring to inverter-only operation on loss of input; it suits small to medium loads where the source is reasonably good and the brief transfer is acceptable. (6.2.4)

NOTE A standby (VFD) UPS passes the utility directly to the load and switches to the inverter only when the input fails; it is the lowest-cost class, used for small, non-critical, or personal-equipment loads where a short transfer time is tolerable, and is not appropriate for the critical loads this standard primarily addresses. (6.2.5)

6.3 Transformer-Free vs. Transformer-Based

6.3.1 The power train construction shall be as indicated in the datasheet.

Power Train Constructionradio

○ Transformer-free (transformerless)

○ Transformer-based (output isolation transformer)

6.3.2 The construction shall be selected for the required galvanic isolation, the output neutral arrangement, and the efficiency and footprint goals.

NOTE Transformer-free designs are the predominant modern construction, offering higher efficiency, lower weight, and a smaller footprint, while transformer-based designs provide galvanic isolation and a derived output neutral that some installations require for grounding or for fault isolation between input and output. (6.3.3)

6.3.4 Where the output is to be a separately derived system with its own neutral-to-ground bond, the need for an output isolation transformer shall be confirmed with the grounding design per Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

7 Capacity and Load

NOTE The UPS shall be sized to carry the critical load continuously at the design ambient and altitude, with margin for load growth, and shall not be loaded beyond its continuous kW rating. (7.1)

7.2 Output Apparent Power

7.2.1 The output apparent power (kVA) rating shall be as indicated in the datasheet and shall equal or exceed the connected critical load apparent power at the design load power factor, with the specified design margin.

Output Apparent Power Ratingrange

kVA

136102040608010016020030040050075010001500

Per drawings — UPS schedule (deferred by default)

7.3 Output Real Power

7.3.1 The rated output power factor shall be as indicated in the datasheet.

Rated Output Power Factorselect

Unity (1.0) — kW rating equals kVA rating

0.9 lagging

0.8 lagging

7.3.2 The UPS continuous real power (kW) rating shall equal or exceed the connected critical load in watts.

NOTE Modern IT power supplies present a near-unity power factor, and a unity-rated UPS delivers its full kVA as usable kW; an older 0.8-rated UPS delivers only 80 percent of its kVA as watts, so sizing on kVA alone without confirming the kW rating is a frequent error that leaves the UPS unable to carry its rated watts. (7.3.3)

7.4 Design Load Margin

7.4.1 The design load margin applied in sizing the UPS shall be as indicated in the datasheet.

Design Load Marginselect

10% (well-defined, stable load)

20% (typical)

25% (load growth expected)

Sized for N+1 module redundancy at full load

7.4.2 A design margin shall be applied so that the steady-state load does not exceed the continuous rating and so that growth does not force a premature replacement.

NOTE Loading a UPS very lightly wastes energy because efficiency falls at low load fraction, while loading it near its rating leaves no margin for growth or for the loss of a module in a redundant system; a target operating load near 60 to 80 percent of rating balances efficiency against margin. (7.4.3)

7.5 Output Voltage and Configuration

7.5.1 The output voltage and configuration shall be as indicated in the datasheet.

Output Voltage and Configurationselect

120V, 1Φ 2-wire

120/240V, 1Φ 3-wire

208Y/120V, 3Φ 4-wire

480Y/277V, 3Φ 4-wire

480V, 3Φ 3-wire (with downstream PDU transformer)

Per drawings — one-line diagram (deferred by default)

7.5.2 The output voltage and configuration shall match the distribution it serves, including the neutral where line-to-neutral loads are present.

7.5.3 A three-phase UPS serving line-to-neutral (120V or 277V) loads shall provide a neutral rated for the unbalanced and harmonic neutral current the nonlinear loads produce.

8 Output Performance

8.1 Crest Factor and Nonlinear Load Capability

8.1.1 The UPS shall sustain the rated load at the peak-to-RMS current crest factor indicated in the datasheet without exceeding its output voltage distortion limit or derating.

Rated Load Crest Factorselect

3:1 (standard nonlinear / IT load)

2.5:1

Linear load (no nonlinear capability)

NOTE Switch-mode power supplies draw current in narrow peaks with a crest factor near 3:1, and a UPS rated only for linear loads will distort its output or derate when it sees this current; specifying a 3:1 crest factor confirms the unit was designed for real IT loads. (8.1.2)

8.2 Output Voltage Distortion

8.2.1 The output voltage total harmonic distortion shall not exceed the value indicated in the datasheet into the IEC 62040-3 nonlinear reference load at full rated load.

Maximum Output Voltage THD into Nonlinear Reference Loadselect

2% THD

3% THD

5% THD

8.2.2 Output voltage THD shall be stated into a nonlinear reference load, not into a linear load, because a UPS that looks clean on a resistive load can distort badly under the real nonlinear load it will serve.

8.3 Output Voltage Regulation

8.3.1 Steady-state output voltage shall be regulated within the tolerance indicated in the datasheet across the full load and battery range.

Steady-State Output Voltage Regulationselect

±1%

±2%

±3%

8.3.2 Transient output voltage deviation for a 100 percent load step shall recover within the manufacturer's published settling time and shall be within the IEC 62040-3 dynamic performance classification specified for the load.

8.4 Output Frequency

8.4.1 The output frequency shall be as indicated in the datasheet.

Output Frequencyselect

60 Hz

50 Hz

NOTE 60 Hz is the North American norm and is the datasheet default; the 50 Hz rating exists for equipment serving a 50 Hz system and is a distinct product selection. (8.4.2)

8.4.3 On battery, the output frequency shall be held to the inverter's internal reference within the manufacturer's published tolerance, independent of any input frequency.

8.4.4 When synchronized to the bypass source, the UPS shall track the source within a settable slew rate so that a transfer to static bypass is made without an out-of-phase break in the output.

9 Input Performance

9.1 Input Current Harmonic Distortion

9.1.1 The input current total harmonic distortion at full load shall not exceed the value indicated in the datasheet, with any input filter required to achieve it furnished with the UPS.

Maximum Input Current THD (THDi) at Full Loadselect

3% THDi (active PFC rectifier)

5% THDi

10% THDi

Higher than 10% with an input filter to meet IEEE 519

NOTE A modern active power-factor-corrected rectifier holds input THDi below about 3 percent and input power factor near unity across the load range, which limits the harmonic burden the UPS places on the upstream system and on any generator; older rectifiers draw highly distorted current that can force upstream equipment and generators to be oversized. (9.1.2)

9.1.3 The input THDi limit shall be coordinated with the harmonic limits of GeneratorsEngine GeneratorsResolves to the current edition.sync/generators for the generator that backs the UPS, and with IEEE 519 at the point of common coupling.

9.2 Input Power Factor

9.2.1 The input power factor at full load shall not be less than the value indicated in the datasheet.

Minimum Input Power Factor at Full Loadselect

0.99 (active PFC)

0.95

0.9

9.3 Input Walk-In and Inrush

9.3.1 The rectifier shall include a soft-start (walk-in) that ramps the input current over a settable interval on source restoration, so that the simultaneous return of several UPS units does not overload the generator or trip the upstream breaker.

9.3.2 The walk-in interval shall be coordinated with the generator's load-acceptance capability per GeneratorsEngine GeneratorsResolves to the current edition.sync/generators.

10 Energy Storage and Autonomy

10.1 Energy Storage Technology

10.1.1 The energy storage technology shall be as indicated in the datasheet.

Energy Storage Technologyradio

○ Valve-regulated lead-acid (VRLA)

○ Lithium-ion (NFPA 855 / UL 9540 applies)

○ Vented lead-acid (VLA)

10.1.2 The energy storage technology shall be selected for the required autonomy, footprint, service life, operating temperature, and the code stack each technology triggers.

NOTE VRLA batteries are the long-standing default for UPS service, with a low first cost, no special fire code stack, and a familiar maintenance model, at the cost of a relatively short service life (commonly 3 to 7 years in service), temperature sensitivity, and a large footprint per kilowatt-hour. (10.1.3)

NOTE Lithium-ion batteries offer a much longer service life (commonly 10 to 15 years), a far smaller footprint and weight, better high-temperature tolerance, and an integral battery management system, at the cost of higher first cost and the UL 9540 / UL 9540A / NFPA 855 code stack with its clearance, detection, and sometimes suppression requirements. (10.1.4)

NOTE Selecting lithium-ion brings NFPA 855 and UL 9540 into scope and shall not be done without confirming the AHJ position, the required clearances, and any fire detection or suppression for the battery space. (10.1.5)

10.2 Autonomy

10.2.1 The battery autonomy at the design load shall be as indicated in the datasheet.

Battery Autonomy at Design Loadrange

min

510153060

Per drawings — UPS schedule (deferred by default)

10.2.2 The autonomy (runtime) shall be specified at the design load and shall cover the worst-case time from loss of normal power until a long-duration source assumes the load or the load is shut down in an orderly manner.

NOTE Where a generator backs the UPS, the autonomy need only bridge the generator start, transfer, and stabilization plus margin, and 5 to 10 minutes is conventional; where there is no generator, the autonomy shall cover the full intended ride-through or an orderly shutdown of the protected load, and undersized autonomy is the single most common UPS specification failure. (10.2.3)

10.3 Runtime Sizing

10.3.1 The battery shall be sized per IEEE 1184 at the design load in watts, accounting for the inverter efficiency, the minimum end-of-discharge voltage, the design autonomy, the minimum battery temperature, and an aging factor so that the autonomy is met at end of battery life.

10.3.2 The runtime sizing shall use the constant-power (watts) discharge method appropriate to a UPS, not a constant-current method, because the inverter draws increasing current from the battery as the battery voltage falls during a discharge.

NOTE The runtime sizing shall be performed at the design load, and the resulting autonomy at other load fractions shall be reported, because runtime is not linear with load. (10.3.3)

10.4 Battery Arrangement

10.4.1 The physical arrangement of the energy storage subsystem shall be as indicated in the datasheet.

Battery Arrangementselect

Internal to UPS cabinet

Matching external battery cabinet(s)

Open battery rack in a dedicated battery room

Integrated lithium-ion battery cabinet with BMS

10.4.2 The string configuration shall be as indicated in the datasheet.

Battery String Configurationselect

Single string

Multiple parallel strings (string redundancy / extended runtime)

NOTE The arrangement and the string configuration both follow from the selected technology, the required autonomy, and the space available, so neither field carries a default. (10.4.3)

10.4.4 Each battery string shall have its own overcurrent and disconnecting means so that a string can be isolated for service without dropping the others.

NOTE Multiple parallel strings provide both extended runtime and a measure of redundancy, since the loss of one string degrades but does not eliminate the autonomy, and they allow a string to be serviced while the others carry the reserve. (10.4.5)

10.5 Battery Disconnect

10.5.1 A disconnecting means shall be provided in the battery DC circuit in accordance with NFPA 70 Article 480, located so that the battery can be isolated from the UPS for service.

10.5.2 The battery disconnect shall be rated to interrupt the maximum DC short-circuit current the battery can deliver.

10.6 Battery Ventilation

10.6.1 The hydrogen ventilation provided for the battery space shall be as indicated in the datasheet.

Battery Space Hydrogen Ventilationselect

Not required (lithium-ion / sealed)

Natural ventilation (small VRLA, per code)

Continuous mechanical ventilation

Mechanical ventilation initiated by hydrogen detection

NOTE The required ventilation follows from the energy storage technology selected and the size of the installation, so the field carries no default. (10.6.2)

10.6.3 Where VRLA or vented batteries are used, the battery space shall be ventilated to keep hydrogen below 25 percent of its lower flammable limit (1 percent by volume in air), in accordance with the applicable building and fire codes.

NOTE Lithium-ion battery spaces do not evolve hydrogen in normal operation, but they have their own NFPA 855 ventilation, off-gas detection, and clearance requirements that shall be met where lithium-ion is selected. (10.6.4)

11 Bypass

11.1 A UPS has two distinct bypass paths — an internal static (electronic) bypass for fast automatic transfer and an external maintenance (wraparound) bypass for servicing the unit — and both shall be provided for a system that must remain energized during service.

11.2 Internal Static Bypass

11.2.1 The UPS shall include an integral static (solid-state) bypass that transfers the load from the inverter to the bypass source without interruption on an inverter fault, an overload beyond the inverter's capability, or a low-battery shutdown.

11.2.2 The static bypass shall retransfer the load to the inverter automatically when the fault clears and the inverter is synchronized, without an out-of-phase break.

11.2.3 The inverter and the bypass source shall be kept in synchronism within the manufacturer's settable window so that a static transfer in either direction is seamless to the load.

11.2.4 The static bypass shall be rated to carry the full load continuously and to pass the downstream fault current required to clear a branch overcurrent device, so that a downstream fault is cleared selectively rather than collapsing the inverter.

11.3 External Maintenance Bypass

11.3.1 Whether an external maintenance bypass is furnished with the UPS shall be as indicated in the datasheet.

External Maintenance (Wraparound) Bypassradio

● Provided — make-before-break, allows full UPS isolation

○ Not provided (redundant modules provide concurrent maintenance)

11.3.2 An external maintenance bypass shall be provided so that the UPS, including its static bypass and its battery, can be completely isolated for service while the load remains energized from the bypass source.

11.3.3 The external maintenance bypass shall be a make-before-break device, so that the transfer of the load to and from the bypass occurs with no interruption to the load.

11.3.4 The maintenance bypass shall include positive isolation (a means to lock out the UPS input and output) so that a technician can work on a de-energized UPS while the load is carried on bypass.

NOTE A UPS without a maintenance bypass forces the entire critical load onto raw utility, or a planned shutdown, every time the unit needs service; the absence of a maintenance bypass is a frequent and costly omission that surfaces only when the first service event arrives. (11.3.5)

11.3.6 Where the UPS is part of a redundant (N+1 or 2N) system in which any single unit can be fully isolated and serviced while the others carry the load, a per-unit maintenance bypass may be omitted provided the system design gives equivalent concurrent maintainability.

12 Redundancy

12.1 Redundancy Configuration

12.1.1 The system redundancy configuration shall be as indicated in the datasheet.

System Redundancy Configurationselect

N (single module, no redundancy)

N+1 (parallel, one redundant module)

Parallel capacity (modules summed for capacity, no redundancy)

2N (two fully independent systems)

Dual-bus / 2(N+1) (two independent redundant systems)

12.1.2 The redundancy configuration shall be selected for the availability the critical load requires and shall be reflected on the system one-line diagram.

NOTE In an N configuration a single module carries the load and its failure or service drops the load; in N+1 the modules operate in parallel with one more than needed, so any single module can fail or be serviced without dropping the load; in 2N the entire system is duplicated as two independent paths; and a dual-bus arrangement feeds dual-corded loads from two independent (often each N+1) systems so that an entire system can be lost or maintained with no load impact. (12.1.3)

NOTE A 2N or dual-bus system depends on the downstream loads being dual-corded so they can accept power from either path; specifying system-level 2N for single-corded loads spends the redundancy budget without removing the single point of failure at the load. (12.1.5)

13 Efficiency and Operating Mode

13.1 Operating Mode

13.1.1 The normal operating mode of the UPS shall be as indicated in the datasheet.

Normal Operating Moderadio

● Double-conversion (online) at all times

○ Energy-saver / eco mode with automatic transfer to double-conversion

13.1.2 The normal operating mode shall be selected for the balance between energy efficiency and the protection level the load requires.

NOTE In double-conversion mode the load is always supplied through the inverter and is fully protected, at the unit's double-conversion efficiency; in energy-saver (eco) mode the load is normally supplied through the bypass at very high efficiency and the inverter is engaged only when a disturbance is detected, trading a small protection margin and a brief transfer for a few points of efficiency. (13.1.3)

NOTE Where eco mode is enabled, the manufacturer's transfer time from eco to double-conversion shall be confirmed to be within the ride-through of the connected load, and eco mode shall not be used for loads that cannot tolerate the brief transfer. (13.1.4)

13.2 Efficiency

13.2.1 The double-conversion efficiency at the expected operating load shall not be less than the value indicated in the datasheet, measured per the ENERGY STAR or DoE test method.

Minimum Efficiency at Rated Load (Double-Conversion Mode)range

%

94959697

13.2.2 Efficiency shall be evaluated at the expected operating load fraction, not only at full load, because UPS efficiency falls at low load and most units operate well below nameplate; a unit efficient at 100 percent load may be poor at the 30 to 50 percent load it actually carries.

13.2.3 Whether an ENERGY STAR listing is required shall be as indicated in the datasheet.

ENERGY STAR Listingradio

○ Required (ENERGY STAR listed)

○ Not required

13.2.4 Where the datasheet requires it, the UPS shall be listed under the ENERGY STAR program for uninterruptible power supplies.

NOTE An ENERGY STAR listing is a procurement screen tied to the Owner's energy program and to any utility incentive pursued, so the field carries no default. (13.2.5)

14 Monitoring and Communications

14.1 Communications Interfaces

14.1.1 The UPS shall provide the network communications interfaces indicated in the datasheet for monitoring and for orderly shutdown signaling to the protected equipment.

Network Communications Protocolscheckbox

☑ SNMP (network management)

☐ Modbus TCP/RTU

☐ BACnet (building automation)

☑ Web/HTTPS interface

☐ USB / serial (local)

14.1.2 BACnet or Modbus points reported to the building management system shall be coordinated with Electrical RoomsElectrical RoomsResolves to the current edition.sync/electrical-rooms and the facility monitoring scope.

14.2 Dry-Contact Indications

14.2.1 The UPS shall provide dry-contact outputs for the status points indicated in the datasheet, wired to a terminal block for connection to the facility annunciator, building management system, or SCADA.

Dry-Contact Status Pointscheckbox

☑ On battery (input power failed)

☑ Low battery / shutdown imminent

☑ On static bypass

☑ On maintenance bypass

☑ Summary alarm (UPS fault)

☑ Overload

☑ Battery test fail / battery fault

14.2.2 The UPS shall provide local visual indication of its operating state — normal, on battery, on bypass, and fault — and an audible alarm for the on-battery and fault conditions.

14.3 Local Display

14.3.1 The UPS shall provide a local display showing input and output voltage and current, load percent, battery voltage and estimated remaining runtime, operating mode, and active alarms.

15 Emergency Power Off

15.1 EPO Interface

15.1.1 The emergency power off interface shall be as indicated in the datasheet.

Emergency Power Off (EPO) Interfaceradio

○ Provided — remote EPO input wired to room EPO system

○ Provided — local EPO

○ Not provided

NOTE Whether an EPO is required, and whether it must be remote, follows from whether the space is governed by NFPA 70 Article 645 and from the room EPO design, so the field carries no default. (15.1.2)

15.1.3 Where the UPS serves a space requiring emergency power off under NFPA 70 Article 645, the UPS shall accept a remote EPO signal that disconnects the load and the battery and shuts down the UPS, in coordination with the room EPO system.

15.1.4 Activation of the EPO shall disconnect the UPS output and open the battery, so that the EPO truly de-energizes the critical load and is not bypassed by the stored energy in the battery.

15.1.5 The EPO wiring and its coordination with any disconnection of the room HVAC and other systems shall be as shown on the EPO control diagram.

15.1.6 A miswired or uncoordinated EPO is a known cause of both unintended outages (nuisance trips) and of a failure to truly de-energize during an emergency; the EPO circuit shall be verified end to end during commissioning.

16 Grounding

NOTE The UPS enclosure, the battery enclosure, and the input and output equipment grounding conductors shall be bonded in accordance with NFPA 70 and IEEE 1100, coordinated with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding. (16.1)

16.2 Where the UPS output is a separately derived system, the output neutral shall be bonded to ground at a single point and the grounding electrode connection shall be made in accordance with NFPA 70 for separately derived systems.

NOTE Whether the UPS output is a separately derived system depends on the topology and the presence of an output isolation transformer, and the determination shall be made explicitly and reflected on the grounding plan, because a wrong assumption produces either a missing neutral-to-ground bond or an unwanted parallel neutral path. (16.3)

17 Installation

17.1 Coordination and Clearances

17.1.1 The UPS, the battery enclosure, and the maintenance bypass shall be located and arranged to provide the working clearances of NFPA 70 Article 110.26 and the manufacturer's required service and airflow clearances, whichever are greater.

17.1.2 UPS location and arrangement within the room shall be per the equipment room layout drawings.

17.1.3 The floor loading of the UPS and the battery shall be confirmed against the structural capacity, because battery cabinets in particular impose a high concentrated floor load.

17.2 Heat Rejection

17.2.1 The UPS heat rejection at the expected operating load shall be coordinated with the room cooling so that the space stays within the UPS and battery rated temperature, per Electrical RoomsElectrical RoomsResolves to the current edition.sync/electrical-rooms.

17.2.2 UPS losses appear as heat in the room, and a UPS that is efficient at full load still rejects meaningful heat at part load; the room cooling shall be sized to the actual heat rejection, not assumed negligible.

17.3 Conductor Connections

17.3.1 Input, output, bypass, and battery conductors shall be sized for ampacity, voltage drop, and the applicable derating, and terminated per the manufacturer's instructions, coordinated with Conductors And CablesConductors and CablesResolves to the current edition.sync/conductors-and-cables.

17.3.2 The output neutral conductor of a three-phase UPS serving line-to-neutral nonlinear loads shall be sized for the harmonic neutral current, which can exceed the phase current.

17.4 Battery Installation

17.4.1 Batteries shall be installed, interconnected, and torqued per the manufacturer's instructions, and the string voltage and polarity shall be verified before the battery is connected to the UPS.

17.4.2 Lithium-ion battery installation shall provide the clearances and any fire detection or suppression required by the NFPA 855 evaluation and the listing.

17.5 Labeling

17.5.1 The UPS, the battery enclosure, the battery disconnect, and the maintenance bypass shall be permanently labeled identifying the system designation, ratings, and source.

17.5.2 An arc-flash warning label per NFPA 70E shall be applied to the UPS and the battery enclosure.

17.5.3 A label shall warn that multiple sources are present and that the load may be energized from the bypass or the battery even when the input is open.

18 Testing and Commissioning

18.1 Factory Tests

18.1.1 Factory acceptance test witnessing shall be as indicated in the datasheet.

Factory Test Witnessingradio

○ Witnessed factory test required

● Certified factory test report (unwitnessed)

18.1.2 The UPS shall receive the manufacturer's standard production and burn-in test, including verification of output regulation, transfer to and from static bypass, and the alarm functions, with a certified report provided.

18.1.3 Where a witnessed factory test is specified, the test shall demonstrate the unit at rated load, the transfer between modes, and the battery operation at the manufacturer's facility before shipment.

18.2 Field Commissioning

18.2.1 The Contractor shall engage a qualified commissioning agent to perform field acceptance testing per ANSI/NETA ATS and the manufacturer's commissioning procedure after installation and before the UPS is placed in service.

18.2.2 Field commissioning shall include as a minimum the following:

Verification of input, output, bypass, and battery connections, grounding, and phase rotation
A load (bank) test at rated load, or at the maximum available load, verifying output voltage, frequency, and regulation
A battery discharge test verifying the autonomy at the design load against the IEEE 1184 sizing
Verification of automatic transfer to and from static bypass on simulated inverter fault and overload
Verification of make-before-break operation of the external maintenance bypass with the load energized
Verification of the EPO, confirming that activation disconnects the output and the battery
Verification of all alarms, dry contacts, and network communications points
Verification of synchronization to the bypass source and of retransfer

Field Commissioning Scopecheckbox

☑ Connections, grounding, and phase rotation verified

☑ Load (bank) test at rated or maximum available load

☑ Battery discharge / autonomy verification against IEEE 1184

☑ Static bypass transfer and retransfer verified

☑ Make-before-break maintenance bypass verified under load

☑ EPO verified (output and battery disconnected)

☑ Alarms, dry contacts, and communications verified

☑ Bypass synchronization verified

NOTE The battery discharge test at commissioning establishes the as-installed autonomy and is the baseline against which future battery aging is judged; a UPS whose runtime was never measured cannot be trusted to ride through the outage it was bought to cover. (18.2.3)

18.3 Integrated System Test

18.3.1 Where the UPS is backed by a generator, an integrated test shall demonstrate the full sequence: loss of normal power, transfer to UPS battery, generator start and stabilization, transfer of the UPS input to the generator, and return to normal, with the critical load energized throughout.

18.3.2 The integrated test shall confirm that the generator accepts the UPS rectifier load, including the rectifier walk-in, without instability, coordinated with GeneratorsEngine GeneratorsResolves to the current edition.sync/generators and Automatic Transfer SwitchesAutomatic Transfer SwitchesResolves to the current edition.sync/automatic-transfer-switches.

19 Delivery, Storage, and Handling

19.1 The UPS and the battery shall be delivered in the manufacturer's packaging and protected from moisture, dust, and physical damage until installed.

19.2 Batteries shall be stored within the manufacturer's temperature range and shall receive a refreshing charge at the manufacturer's recommended interval if storage is prolonged, because a battery left uncharged on the shelf loses capacity and may be damaged.

19.3 Lithium-ion batteries shall be stored, handled, and transported in accordance with the manufacturer's instructions and the applicable shipping and fire regulations.

20 Warranty

20.1 The UPS unit warranty period shall be as indicated in the datasheet.

UPS Unit Warrantyselect

1 year from substantial completion

2 years from substantial completion

5 years from substantial completion

20.2 The energy storage warranty shall be as indicated in the datasheet.

Energy Storage Warrantyselect

VRLA — 1 year full / prorated to design life

VRLA — 2 year full

Lithium-ion — 5 years

Lithium-ion — 10 years

NOTE The energy storage warranty terms available depend on the technology selected, so the field carries no default. (20.3)

20.4 The UPS and the energy storage subsystem shall be warranted by the manufacturer against defects in materials and workmanship for the specified periods.

20.5 The battery warranty terms, including any prorated portion and the temperature conditions on which the warranty depends, shall be confirmed by the Engineer before the submittal is accepted.

21 Spare Parts

21.1 Spare parts and provisions shall be furnished as indicated in the datasheet.

Spare Parts and Provisionscheckbox

☐ Spare control / logic board or critical subassembly

☑ Spare cooling fans (one set)

☑ Spare input/output fuses (one set of each rating)

☐ Spare battery modules / blocks

☑ Software and licenses for monitoring

21.2 Spare parts, where provided, shall be the same type and rating as those installed and shall be stored in the electrical or UPS room, labeled with the equipment they serve.

NOTE A maintenance and replacement contract should be considered for mission-critical UPS systems, because the battery is a consumable with a defined service life and the system's value depends on the battery being replaced before it fails an in-service discharge. (21.3)