February 21, 2008

Efficiency Standards for Power Adapters

In a previous post I wrote about various programs and regulations aimed at increasing PSU efficiency.

Here is a brief update. On December 19th, 2007, the Energy Independence and Security Act of 2007 (EISA 2007) that is intended to reduce US Oil Dependence, became law. Although the act is aimed mainly at improving vehicles fuel economy and increasing the production of clean renewable fuels, it contain sections that affect power supplies.
Particularly, Section 301 External Power Supply Efficiency Standards establishes energy conservation standards that take effect on July 1, 2008 for so called “Class A External Power Supplies,” and establishes the processes to review and possibly amend those standards.
The term "class A external power supply' means basically a single output low-voltage AC-AC or AC-DC converter under 250W that is intended to be used with a separate end-use product.
According to this law, a class A external power supply manufactured on or after July 1, 2008 should meet specific efficiency standards depending on its nameplate power Po. For example, in the power range from 1 to 51 W [which is typical for most adapters] if you convert EISA requirement into percentage, the minimum efficiency in active mode should be 50% + 9*Ln(Po), where Ln(Po) is natural logarithm of the nameplate output power.

EISA 2007 requires US Depratment of Energy to issue a final rule prescribing energy conservation standards for battery chargers, if technologically feasible and economically justified, by July 1, 2011. DOE will also have to complete the determination on non-Class A external power supplies by a new deadline of December 19, 2009.

Note that unlike voluntary Energy Star® and 80 PlUS® programs, the above requirements are mandatory.