View Single Post - Seasonic Power Angel Power Monitor

zepper · Rated PG

I thought you might want to know that there is another device out there very similar to the Power Angel (probably built on the same PCBs). It is the P3 Kill A Watt meter. It is nearly identical but I have been able to find it for a bit less $$$ than the PA (the best I've found for the PA is ~$35. +SHTx). The best price for the K-A-W (~$32. shipped) is from a guy in Hawaii via eBay.
. I have written a review of it on http://www.techimo.com/reviews/ .
. Now to your review. Your explanation of Power Factor wasn't very accurate. The number that expresses power factor is the Cosine of the phase shift angle between the current sine wave and the voltage sine wave. Since the Cosine of 0 deg. is 1, then that is the ideal and what is approached by PSUs that have active PFC (power factor compensation or correction). The description of 'Efficiency' is what you used to describe Power Factor. PF is a component of the efficiency number which is expressed in % (percent) (power out/power in x 100). IOW, the power factor of 1 is the PF of a resistor which is the most friendly load to put on the power grid. So perhaps if everyone had all their equipment PF corrected, the power company might not have to build more capacity quite as soon (that's why aPFC is required in Europe). And if you had several hundred PCs and switched all of them to PFC PSUs from non-PFC, you could save a couple bucks on your power bill.
. That brings me to the last paragraph of Page 2 where you were testing a small PSU with the Seasonic load (it would be nice if you would post a reseller link or two for that). The PSU is rated at 200W, and you were measuring about 200 Watts in from the wall. Assuming a typical switching PSU efficiency of 65% , then the PSU was actually outputting around 130 Watts into the load - nowhere near its rating... To get the exact output you would have to measure the output voltage and current on the rails that were actually being loaded with a DMM (Digital MultiMeter) and add them up. With that total, you could then calculate the actual efficiency of that PSU per the formula above. Perhaps that could be a useful addendum to any PSU review you may do here in the future - thanks to the Power Angel, of course... Wink

. I hope you find this enlightening.
.bh.

Wave

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