CUI Inc: External Power Supplies: How to Be Ready for Tough New Efficiency Standards in Effect from 2016

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By: Jeff Schnabel, Vice-President of Global Marketing, CUI Inc

The global regulatory environment surrounding the legislation of external power supply efficiency and no-load power draw has rapidly evolved over the past decade since the California Energy Commission (CEC) implemented the first mandatory standard in 2004. With the publication of a new set of requirements by the US Department of Energy (DoE) set to go into effect in February 2016, the landscape is set to change again as regulators try to further reduce the amount of energy consumed by external power adapters.

Mandating higher average efficiencies in external power supplies has undoubtedly had a real impact on global power consumption. However, with the benefit of a reduced draw on the power grid come challenges and uncertainties for the electronics industry as it tries to keep up with this dynamic regulatory environment.

OEMs which design external power supplies into their products must continue to monitor the latest regulations to ensure that they are in compliance in each region where their product is sold. While the new standards enacted by the DoE will only be mandatory in the US, any OEM wanting to supply products in the US should be taking action now to ensure that they comply.

The Evolution of Efficiency Regulation
In the early 1990s, it was estimated that there were more than one billion external power supplies in use in the US alone. The efficiency of these power supplies, which mainly used linear technology, could be as low as 50%, and still drew power when the application was turned off or not even connected to the power supply (commonly known as the ‘no-load’ condition). Experts calculated that without efforts to increase efficiency and reduce no-load power consumption, external power supplies would account for around 30% of total energy consumption in less than 20 years.

As early as 1992, the US Environmental Protection Agency started a voluntary program to promote energy efficiency and reduce pollution; it eventually became the Energy Star program. It was not until 2004, however, that the first mandatory regulation governing efficiency and no-load power was put in place, and there has been constant change since then (see Figure 1).

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Figure 1: The development of efficiency regulations worldwide since 2004

Today, the US and Canada mandate Level IV efficiency, while Europe sets a higher Level V standard. From February 2016, however, the US DoE will require compliance with the more stringent Level VI standard. Power supply manufacturers indicate compliance by placing a Roman numeral on the power supply label as specified by the International Efficiency Marking Protocol for External Power Supplies version 3.0, updated in September 2013. This latest version of the Protocol provides additional flexibility on where the marking may be placed (see Figure 2).

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Figure 2: Efficiency markings on external power supplies are governed by international protocol

While the European Union is, as of October 2015, the only governing body to enforce compliance to the Level V standard, most external power supply manufacturers have adjusted their global product portfolios to meet these requirements. This is in response to the needs of OEMs to have a universal power supply platform for products that are shipped globally.

The requirement for Level VI compliance in the US from 2016 is likely to induce power-supply manufacturers to adjust their product portfolios again, so that they can market Level VI compliant products globally. How are the specifications of these new products different from today’s Level V power supplies?

New Performance Thresholds
Figure 3 shows in summary the how the efficiency thresholds for external power supplies have become more stringent over time.

The internationally approved test method for measuring efficiency has been published by standards body the International Electrotechnical Commission (IEC) as AS/NZS 4665 Part 1 and Part 2. The tester is required to measure the input and output power at four defined points: 25%, 50%, 75% and 100% of rated power output. Data for all four points are separately reported. An arithmetic average active efficiency across all four points is also calculated.

Some types of external power supplies are exempted from the scope of the standards in both the US and the EU, such as those for some medical devices, for battery chargers, and replacement parts for products first manufactured before July 1, 2008. A low-voltage external power supply – a unit with a nameplate output voltage of less than 6V and a nameplate output current greater than or equal to 550mA – will also be exempt.

Figure 3: A summary of past and current performance thresholds. The term ‘power’ means the power specified on the label of the power supply.

LevelNo-Load Power RequirementAverage Efficiency Requirement
Iused if you do not meet any of the criteria-
IIno criteria was ever establishedno criteria was ever established
III*10 Watts: *0.5W of No-Load Power*10 Watts: *Power x 0.49
1-49 Watts: *[0.09 x Ln[Power]] + 0.49
48-250 Watts:*84%
IV0-250 Watts: *0.5W of No-Load Power*1 Watt: *Power x 0.50
1-51 Watts: *[0.09 x Ln[Power]] + 0.5
50-250 Watts:*85%
VStandard Voltage Ac- Dc Models (>BVout)
0-48 Watts: *0.3W of No-Load Power
Standard Voltage Ac- Dc Models (>BVout)
*1 Watt: 0.48 x *Power x 0.140
VStandard Voltage Ac- Dc Models (>BVout)
50-250 Watts: *0.5W of No-Load Power
Standard Voltage Ac- Dc Models (>BVout)
1-51 Watts: *[0.09 xLn[Power]] + 0.622
V-Standard Voltage Ac- Dc Models (>BVout)
50-250 Watts:*87%
VLow Voltage Ac- Dc Models ( 0-48 Watts: *0.3W of No-Load PowerLow Voltage Ac- Dc Models ( *1 Watt: 0.497 x *Power x 0.067
VLow Voltage Ac- Dc Models ( 50-250 Watts: *0.5W of No-Load PowerLow Voltage Ac- Dc Models ( 1-49 Watts: *[0.0750 xLn[Power]] + 0.561
V-Low Voltage Ac- Dc Models ( 50-250 Watts:*86%

The Migration to Level VI Efficiency
Power supply manufacturers such as CUI are already prepared for the coming transition to the more stringent Level VI standards. This has not only called for design modifications to meet tightened regulations for existing adapters, the new standard also expands the range of products within the scope of the standard. Regulated products will now include:
- Multiple-voltage external power supplies
- Products with power levels above 250W

The new performance thresholds are summarized in the tables below.

The new standard also defines power supplies as being either for direct or indirect operation. A direct-operation product is an external power supply which functions in its end product without the assistance of a battery. An indirect-operation power supply is not a battery charger, but cannot operate the end product without the assistance of a battery. The new standard only applies to direct-operation external power supplies. Indirect-operation models will still be governed by the limits defined by EISA2007.

It is expected that other nations will soon follow the US’s lead and implement Level VI efficiency standards. In the EU, the mandatory European Ecodesign Directive for external power supplies is currently under revision; it is expected to harmonize with most, if not all, of the US standards. It should be expected that countries with existing efficiency regulations in-line with the US’s, including Canada and Australia, will also move to harmonize with the new standard.

Summary
The EPA estimates that external power-supply efficiency regulations implemented over the past decade have saved some $2.5bn annually and reduced CO2 emissions by more than 24 million tons per year. Moving beyond the mandated government regulations, many OEMs are now starting to demand greener power supplies as a way to differentiate their end products, driving efficiency continually higher and even pushing the implementation of control technologies which in some cases eliminate no-load power consumption altogether.

In late 2014, CUI began introducing Level VI compliant adapters to keep their customers one step ahead of the coming legislation. In the future, CUI will continue to look for ways to implement the latest energy-saving technologies into its external power supplies in order to address market demands and to comply with current and future regulations.

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Level VI: Single-Voltage External AC-DC Power Supply, Basic-Voltage
Single-voltage external AC-DC power supply: an external power supply which is designed to convert line-voltage AC into lower voltage DC output, and is able to convert to only one DC output voltage at a time.

Nameplate Output Power (Pout)Minimum Average Efficiency in Active Mode (expressed as a decimal)Maximum Power in No-Load Mode (W)
1W0.5 x Pout + 0.160.100
1W < Pout 49W0.071 x ln (Pout) - 0.0014 x Pout + 0.670.100
49 W < Pout 250W0.8800.210
Pout > 250W0.8750.500

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Level VI: Single-Voltage External AC-DC Power Supply, Low-Voltage
Low-voltage external power supply: an external power supply with a nameplate output voltage lower than 6V and nameplate output current greater than or equal to 550mA. Basic-voltage external power supply means an external power supply that is not a low-voltage power supply.

Nameplate Output Power (Pout)Minimum Average Efficiency in Active Mode (expressed as a decimal)Maximum Power in No-Load Mode (W)
1W0.517 x Pout + 0.0870.100
1W < Pout 49W0.0834 x ln (Pout) - 0.0014 x Pout + 0.6090.100
49 W < Pout 250W0.8700.210
Pout > 250W0.8750.500

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Level VI: Single-Voltage External AC-AC Power Supply, Basic-Voltage
Single-voltage external AC-AC power supply: an external power supply which is designed to convert line-voltage AC into a lower voltage AC output and is able to convert to only one AC output voltage at a time.

Nameplate Output Power (Pout)Minimum Average Efficiency in Active Mode (expressed as a decimal)Maximum Power in No-Load Mode (W)
< Pout < 1W0.5 x Pout + 0.160.210
1W < Pout 49W0.071 x ln (Pout) - 0.0014 x Pout + 0.670.210
49 W < Pout 250W0.8800.210
Pout > 250W0.8750.500

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Level VI: Single-Voltage External AC-AC Power Supply, Low-Voltage

Nameplate Output Power (Pout)Minimum Average Efficiency in Active Mode (expressed as a decimal)Maximum Power in No-Load Mode (W)
1W0.517 x Pout + 0.0870.210
1W < Pout 49W0.0834 x ln (Pout) - 0.0014 x Pout + 0.6090.210
49 W < Pout 250W0.8700.210
Pout > 250W0.8750.500

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Level VI: Multiple-Voltage External Power Supply
Multiple-voltage external power supply: an external power supply which is designed to convert a line-voltage AC input into more than one simultaneous lower-voltage output.

Nameplate Output Power (Pout)Minimum Average Efficiency in Active Mode (expressed as a decimal)Maximum Power in No-Load Mode (W)
1W0.497 x Pout + 0.0670.300
1W < Pout 49W0.075 x ln (Pout) + 0.5610.300
Pout > 49W0.8600.300

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