External power supplies (EPS) convert household electric current from a wall outlet into lower voltage direct current (DC) or alternating current (AC) to operate consumer products such as a laptop computer. External power supplies are so-called (“external”) because they come in a separate physical enclosure than the end-product, and usually provide power to the device through a separate cord and plug.
The efficiency rating of a power supply is the percentage of total output DC power in relation to total input AC power. It is a measure of how much of the power is lost when it converts the AC wall outlet power to DC (with most of the loss during conversion taking the form of heat). As an example, consider that if a device consumes 300W of power, using a power supply unit with 85% efficiency will require about 350W of input power, and a 70% efficient supply will pull nearly 430W of power from the wall.
More than 1 billion external power supplies are shipped per year, and the average American home has five to ten of these components powering devices in their homes. Considering the prevalence of these units, they have attracted attention from regulatory bodies due to the fact that they draw considerable power even under no-load conditions; when the device is turned off or disconnected. To address this situation the U.S. Department of Energy has, over the past decade, instituted standards for external power supply efficiency. The U. S Environmental Protection Agency (EPA) estimates that these external power supply efficiency regulations have reduced energy consumption by 32 billion kW, saving $2.5 billion annually and reducing CO2 emissions by more than 24 million tons per year.
Right now an original equipment manufacturer (OEM) will need an external power supply that meets Level V efficiency standards, but as of Feb. 10, 2016, newer, Level VI requirements take effect. The new regulations increase the minimum efficiency regulations, as well as expand the range of products applicable under the standard. The rule will have implications for any OEM that designs products with an external ac-dc power supply for the U.S. market and these companies should be taking action now to ensure compliance.
According to estimates by the DoE, the move to Level VI will save around 47 million tons of CO2 emissions. The DoE also calculates that by 2030, Level VI power supplies could deliver annual energy savings of around 8.9 million mW/h.
Under Level VI, efficiency in active mode—the adapter is powered up and supplying power to the end product—is increased by roughly 5%. The new regulations also apply at no load when the adapter is plugged into the wall—like a cell phone charger—but nothing is connected to it. Here, power consumption at Level IV was .5w and at Level VI it has been lowered to 1w. That is a small decrease, but remember that the savings will add up quickly because there will be millions of adapters in use.
The new rule applies to external power supplies categorized into eight product classes. It also extends the scope of regulation to encompass lower voltage AC- or DC-output EPS’s, multiple-voltage EPS units and EPS with nameplate output power exceeding 250w.
Multiple-voltage EPS simply means an external power supply that is designed to convert line voltage AC input into more than one simultaneous lower-voltage output. Single-voltage EPS is designed to convert line voltage into lower-voltage output, too, but to only one output voltage at a time.
A lower-voltage external power supply is defined here as an EPS with a nameplate output voltage less than 6vs and nameplate output current greater than or equal to 550 milliamps.
The EPA’s Energy Star program has a labeling protocol for energy-efficient external power supplies. The protocol calls for manufacturers to identify the efficiency level of each power supply unit using a printed roman numeral on the label, depending on the efficiency of the unit (currently I to V). EPA will now allow external supplies meeting level VI standards to be designated Energy Star with a roman VI.
Some classes of direct power supplies are exempt. These include devices that require FDA approval, such as a medical device in accordance with section 513 of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 360c). The revision also differentiates between “direct operation” and “indirect operation” power supplies. Indirect operation products are not affected by the new requirements. A direct operation external power supply means an external power supply that can operate a consumer product that is not a battery charger without the assistance of a battery. Conversely an indirect operation EPS is one that cannott operate a product (not a battery charger) without the assistance of a battery. The regulation includes a process to determine whether an end product is considered direct or indirect in operation. Indirect supplies only have to continue to comply with the existing EISA2007 efficiency limits.
Also exempt are EPS units that are made available as a service part or spare part by the manufacturer of an end-product that was produced before July 1, 2008.
Manufacturers of external power supplies are well along in their efforts to make Level VI product available before the mandatory February 2016 compliance date. Two examples are shown above. Figure 1 shows, the CUI SDI65-UD Series, a 65 W desktop AC-DC power supply featuring a no-load power consumption of less than 0.21 W, and Figure 2 shows, the GlobeTek GT-46200-20VV-x.x-T3, a 20 W desktop regulated switch mode AC-DC adapter with 5-6 VDC output.
Given that the European Union and Australia also have enacted similar legislation soon after U.S. efficiency regulations were raised to Level IV, and in 2011 the European Union also increased its requirement to Level V. It is reasonable to expect that regulating bodies in these and other countries will be in harmony with the new U.S. efficiency standards soon.