ENERGY STAR Program Requirements for Uninterruptible Power Supplies (UPSs) - Partner Commitments, Eligibility Criteria Version 2.0, and Test Method (Rev. Dec-2017)

Overview

The document combines partner commitments, eligibility criteria and the test method for ENERGY STAR certification of UPSs. Products are classed by power conversion (static, rotary, diesel-coupled rotary or DRUPS), by output (ac or dc) and by input dependency: VFD (voltage and frequency dependent), VI (voltage independent) and VFI (voltage and frequency independent). Scope covers consumer, commercial, data center and telecom dc UPSs; industrial, utility, mobile, safety-application and hybrid ac/dc units are excluded.

The efficiency metric is a load-weighted average (EffAVG) of efficiencies measured at percentages of the reference test load. For ac-output UPSs above 10,000 W the weights are 0.25 at 25% load, 0.50 at 50% and 0.25 at 75%, with no weight at 100%. Minimum average efficiency is 0.970 for VFD, 0.940 for VI and 0.0058 x ln(P) + 0.886 for VFI. In the 1,500-10,000 W range, modular UPSs receive a 0.004 EMOD allowance subtracted from the VFD (0.981) and VI (0.980) minimums, and the same allowance appears in the VFI formula for that class.

For multiple-normal-mode UPSs shipped with the highest-dependency (eco) mode enabled, efficiency is rated as 0.75 x low-dependency-mode efficiency + 0.25 x high-dependency-mode efficiency and must meet the threshold of the lowest dependency mode. High-voltage dc-output UPSs and low-voltage (60 V or less) dc-output UPSs/rectifiers must reach at least 0.955 average efficiency; low-voltage units are averaged over 30% to 80% load in 10% steps.

On power factor, input power factor at 100% of the reference load must be at least 0.90 in every VFI and VI normal mode. Diesel-coupled rotary UPSs sold in the US must show diesel engine compliance with 40 CFR part 60 subpart IIII through a certificate of conformity; units sold elsewhere are exempt. The test method calls for a resistive reference load, measurement uncertainty of 0.5% or better at 95% confidence, and stabilisation for 125% of the manufacturer's stabilisation time under IEC 62040-3.

Version 2.0 took effect on January 1, 2019, and a product is judged against the specification in force at its date of manufacture. The notes on future revisions mention that connected functions such as demand response may become criteria. It is a product-certification specification, not a facility-level efficiency guarantee, and the current version should be checked at energystar.gov.

Key points

1. Version 2.0 took effect on January 1, 2019; a product is assessed against the specification in force on its date of manufacture.
2. For ac-output UPSs above 10,000 W, average efficiency is weighted 0.25 at 25% load, 0.50 at 50% and 0.25 at 75%; 100% load carries no weight.
3. Minimum average efficiency above 10,000 W: 0.970 for VFD, 0.940 for VI, and 0.0058 x ln(P) + 0.886 for VFI.
4. Modular UPSs in the 1,500-10,000 W range receive an efficiency allowance (EMOD) of 0.004.
5. Multiple-normal-mode UPSs shipped with eco mode enabled are rated at 0.75 x low-dependency efficiency + 0.25 x high-dependency efficiency.
6. High-voltage dc-output UPSs and low-voltage dc-output UPSs/rectifiers must reach 0.955 average efficiency; low-voltage units are averaged over 30% to 80% load in 10% steps.
7. Input power factor at 100% reference load must be at least 0.90 for all VFI and VI normal modes.
8. Diesel-coupled rotary UPSs sold in the US must show engine compliance with 40 CFR part 60 subpart IIII.
9. Test input voltage precedence starts at 600 V ac delta 60 Hz, then 600Y/346, 480 delta, 480Y/277, down to 120 V ac.
10. The reference test load has a power factor above 0.99 and is resistive; ac units are measured at 100%, 75%, 50%, 25% and 0% load.

Using it in design

• Write the Version 2.0 thresholds into UPS procurement as a floor; for VFI units above 10,000 W compute the minimum from 0.0058 x ln(P) + 0.886 for the actual rating.
• Ask which load points and which input-dependency mode a vendor's efficiency figure refers to; above 10,000 W the 100% point has zero weight and 50% load carries the most.
• If eco mode is considered, weigh the 0.75/0.25 weighted rating against the reduced protection of VFD or VI compared with VFI operation.
• In redundant (N+1, 2N) topologies the UPS often runs lightly loaded, so request 25% load efficiency separately.
• Include the minimum input power factor of 0.90 in generator and distribution sizing, and request the emissions certificate if a DRUPS is considered.

Who should read it

Electrical designers, procurement teams and engineers who select and specify UPS equipment or assess facility efficiency.

Document contents

1. Definitions
2. Scope
3. Certification Criteria
4. Energy Efficiency Requirements for Ac-output UPSs
5. Energy Efficiency Requirements for Dc-output UPSs/Rectifiers
6. Power Factor Requirements
7. Diesel Coupled Rotary UPS Emissions Requirements
8. Testing
9. Effective Date
10. Considerations for Future Revisions
11. Test Method: Overview and Applicability
12. Test Method: Test Setup
13. Test Method: Test Conduct and Procedures
14. References

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Publication details

Authors

U.S. EPA ENERGY STAR

Publisher

U.S. EPA / ENERGY STAR

Year

2017

Document language

English

Source type

Government / public

Access

Open licence — downloadable

Licence

U.S. public domain — U.S. Government work; free to reuse

Licence evidence

www.copyright.gov

Citation