The International Energy Efficiency Marking Protocol for External Power Supplies, which has evolved from an ENERGY STAR initiative in the early 2000s, requires OEMs of equipment such as notebook PCs, printers and consumer products to choose more energy efficient power adaptors for their products. The protocol has been adopted worldwide, but different regions enforce different versions of the specification. Currently, the EU requires all external power supplies marketed within its territories to comply with Level V of the specification: the toughest specification in force today.
The US Department of Energy (DoE) has announced that it will require external power supplies for products marketed in the US to comply with the even stricter Level VI specification after 10 February 2016. By increasing minimum targets for average efficiency and reducing the maximum limits on no load power consumption, the Level VI specification is expected to save some 47million tons of CO2 emissions per year.
Although no other authorities have yet announced plans to adopt Level VI, the reality is that OEMs will need to ship Level VI power adaptors with products intended for sale in all markets. This reflects supply-chain best practice and helps deliver economies of scale, while avoiding logistical errors.
The new specification, which is more complex than Level IV or Level V, extends its scope to include multioutput power supplies. In addition, power supplies of more than 250W are included for the first time. Level VI also introduces separate specifications for AC/DC and AC/AC power supplies, power supplies with output of less than 6V and basic voltage power supplies with output greater than 6V.
Table 1 lists the minimum standards for average efficiency and standby power imposed by the new Level VI specification, for all types of power supplies covered.
By extending the marking protocol to cover power supplies rated at more than 250W, Level VI will apply to a larger variety of industrial applications. These are likely to include some types of portable test gear and equipment installed semi-permanently, such as emergency air conditioners, electronic signage, event lighting or CCTV equipment.
On the other hand, it is worth noting that some types of industrial equipment are not covered by the protocol; these include power supplies that are built into racks, as well as on machine power supplies that are not physically separate from the end use equipment.
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This table shows the limits on efficiency and no-load power imposed by the new Level VI specification
Be sure of exemptions
To ensure compliance with the law, without overspecifying the power supply and incurring unnecessary costs, OEMs also need to understand the types of power supplies that are explicitly exempted from Level VI compliance.
Medical power supplies and other units requiring registration with the US Federal Food and Drug Administration have been exempted under previous protocols and remain exempt, according to level VI. Also exempted are AC/DC power supplies with output rating of less than 3V and 1A used to charge the battery of a device that is fully or primarily motor driven.
On the other hand, Level VI also withdraws some exemptions, such as the exemption for power supplies intended to be marketed as replacement or spare parts.
Moreover, Level VI introduces a distinction between direct and indirect power supplies and is applicable only to direct power supplies.
Simply put, a direct operation external power supply can function in its end product without the assistance of a battery. An indirect operation power supply cannot operate the end product without battery assistance, although it is not a battery charger. A given unit can be identified as a direct or indirect power supply by following guidance from the US DoE.
Remove the battery, if it is removable. Connect the power supply first to mains and then to the device, then immediately attempt to operate the device. If the device operates as intended, the power supply is regarded as direct operation and so must comply with the level VI specification.
If the battery is not removable, ensure it is adequately charged to operate the device. Turn the device off and disconnect the power supply. Turn the device on and record the time taken to become operational to the nearest 5s. Next, run the device on battery power alone until the battery is discharged and the device stops functioning. Connect the power supply first to mains and then to the device. Immediately attempt to operate the device and record the time for it to become operational to the nearest 5s. If this time is greater than the previous time recorded plus 5s, the power supply cannot operate the device directly and therefore is classed as indirect operation.
Ensure compliance
OEMs need to begin preparing for Level VI by reviewing the power supplies shipped with all end use products, assessing any exemptions and taking steps to ensure that any units supplied with manufacture dates later than 10 February 2016 are Level VI compliant.
CUI began introducing Level VI compliant adapters in late 2014 to help customers stay ahead of the coming regulation. The new Level VI designs use CUI’s flyback topology up to 120W and LLC resonant topology for higher power models. However, significant changes have been needed in other areas in order to satisfy the more stringent specifications. These include changes to the secondary side circuitry and a new, more advanced, main control IC capable of adjusting its frequency to optimise efficiency at light loads.
In addition, units with built-in power-factor correction (PFC) are capable of disabling the PFC circuitry when the load is low enough that PFC is not required. Saving the power normally lost in these components helps satisfy the Level VI average efficiency specifications. Other design changes have included reoptimisation of passive component values throughout the power supply and designing in the latest high efficiency power MOSFETs with low on resistance.
Eco-design legislation remains committed to reducing the energy wasted in the power supplies of consumer electrical products and high power industrial equipment. When the US adopts Level VI of the International Energy Efficiency Marking Protocol for External Power Supplies in February 2016, OEMs globally will need to ensure that all power adaptors shipped into the US with their end products are compliant with the new specifications.
Although Level VI encompasses a wide variety of power supply types, the rules are complex and there are a number of exemptions. OEMs need to understand clearly the types of power supplies that are covered, and those that are not, in order to select the right units from among the Level VI power supplies now entering the market. Swift action is needed, to meet the deadline date.
Author profile:
Jeff Schnabel is VP of marketing with CUI.
