Computer Power Supply Units Reach for Top 80 Plus Ratings
Engineers work on new designs and with innovative materials to attain the industry’s highest energy efficiency ratings.
As engineers, it isn’t enough that we design devices that do the job intended, using the least amounts of materials, and that are also cost-effective. We must also prove that our designs meet expected goals by meeting or surpassing industry performance expectations. That is the intention behind an industry standard for power supplies known as 80 Plus.
A Way to Prove Efficiency
80 Plus was created in 2004 by the Electric Power Research Institute (EPRI) and Ecos Consulting as a way to evaluate and promote efficient energy use in computer power supply units (PSUs). Using the program, it is possible to attain 80 Plus certification for PSUs that have greater than 80 percent energy efficiency at 20%, 50%, and 100% of their rated load, and a power factor of 0.9 or greater at 100% load. The power factor is the ratio of real power consumed by the load to the apparent power flowing through the circuit. Energy Star ratings were added to the 80 Plus requirements in 2006.
Image used courtesy of Hans Haase, [CC-BY-SA 3.0]/Wikimedia Commons
There are five voltage categories for 80 Plus certification:
- 115 Volt is for power supplies certified for desktop, workstation, and non-redundant server applications. A redundant power supply has an additional internal power source (usually a battery) that operates if source power is interrupted.
- 115 Volt Industrial is used for power supplies in industrial applications in any physical format
- 230 Volt certifies power supplies certified for redundant, data center applications
- 230 Volt EU Internal power supplies are certified for desktop, workstation, and server applications in non-redundant configurations
- 380 Volt Internal redundant power supplies
Standard, Bronze, Silver, Gold, Platinum and Titanium
Formed in 2007, The Climate Savers Computing Initiative was a group of businesses and environmental conservation organizations that developed efficiency level targets for workstations from 2007 through 2011. These were incorporated into the 80 Plus certification levels. From July 2007 through June 2008, the basic 80 Plus level was in place. In 2009 the 80 Plus Bronze level target was established, increasing performance to 85 percent minimum efficiency for the PSU at 50 percent of rated output (and 82 percent minimum efficiency at 20 percent and 100 percent of rated output). The following year came 80 Plus Silver with an increase to 88% efficiency at 50 % of rated load, then 80 Plus Gold at 90 % in 2010. Next, the Platinum ranking required 92% efficiency at 50% load, and the highest Titanium rating, first reached in 2012, requires 94% efficiency at the 50% load level.
80 Plus ratings. Image used courtesy of CLEAResult
Reaching the high efficiencies required for Titanium certification can be difficult and designers are looking at Gallium Nitride (GaN) semiconductors as a replacement for more-traditional silicon semiconductor technologies. GaN’s wide band gap (3.4 electron-volts versus 1.1 electron-volts for silicon) provides greater efficiencies, faster switching speeds, and a smaller size that can result in lower cost. GaN cannot be directly substituted for silicon semiconductors and the circuitry must be completely redesigned specifically for GaN applications. GaN is relatively new for power devices and engineers are working to understand its characteristics and failure modes. GaN devices are allowing new innovations as designers work toward attaining Titanium 80 Plus certifications.
Efficiency is Key
The goals of the 80 Plus certification, and particularly the enhancements brought about by the Gold, Platinum, and Titanium levels is to help designers and consumers choose the most efficient power supply units for their computer systems. Efficiencies higher than 90 percent mean that the PSU doesn’t waste energy and produces less waste heat. A side benefit is that the computer system operates more quietly because the cooling fan doesn’t need to activate as frequently.
A list of the latest certifications for manufacturers can be found at CLEAResult.