Our Approach For More Accurate Efficiency Measurements
In order to address our issues with the 80 PLUS organization's methodology, we use a custom-made application that gives us full control and allows real-time monitoring of our equipment. This application keeps detailed logs that include efficiency, and we only take the average readings into consideration to provide the highest possible accuracy. We call this app Faganas ATE, named after the first custom-made loader that was compatible with it. This names derives from the Greek word "φαγάνας" which describes someone who eats a lot. In this particular case, Faganas' lunch is PSUs.
The main problem with most labs is that they don’t have a suitable method for monitoring and extracting results from all of their equipment at the same time. In our setup, we use nine different load modules. Throughout a test session, we have to constantly monitor their voltage, amperage, and/or wattage readings. This is simply not possible without using Faganas ATE.
In case monitoring in real time and analyzing the massive data that nine load testers spit out, in addition to monitoring the PSU's performance, isn't hard enough, then the added burden of applying a huge number of loads in sequence surely puts a lot of extra weight on the lab operator's shoulders. In order to apply 1600 different load patterns to any PSU, we designed a simple but effective algorithm implemented in Delphi. This language was popular back in 2010, when we begin developing Faganas. If we started today, we would probably use C# because of the top-notch Visual Studio IDE and better support.
We only consider the +12V, 5V, and 3.3V rails. If we also included 5VSB, the test would last for many days. The minimum load for each rail (usually 0W for modern PSUs with DC-DC converters) is set, along with a load step that we try to keep as low as possible. The last factor, which is extremely important, is how long each load level is applied. Even the slightest change significantly affects how long the complete test suite runs. For example, if we run a total of 1600 load combinations for 10 seconds each, the total duration is 16,000 seconds, or 4:26:40 hours. An increase of only two seconds per test (12 in total) increases that to 5:20:00 hours. That's a 20% increase with just a two-second difference in the load-apply period. As you can imagine, we have to be extra careful with this setting to achieve a combination of high accuracy and reasonable test duration. If electricity bills, the health of our equipment, and time weren't big issues, then we'd run the cross-load metrics for a couple of days to torture-test the PSUs at the same time.
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