
Originally Posted by
KTE
Achim,
Ah OK. The first reading on the meter is watts, the second is the VA and the third the power factor (P(W)/S(VA)=PF i.e., 176.5/185.4 = 0.952 or 95.2%). These meters are incapable of showing PSU efficiency since you need an ammeter or a clamp meter or a SMPS ATE to measure that using values of how much amps each rail is carrying from the PSU and what the voltage for each rail is (multiply the two for the DC wattage) compared to how much VAC is being drawn in. So it's the ratio of how much the PSU pulls and how much it then gives out which is the PSU efficiency. Power factor that is being reported above is very different.
Youre power factor radings are how they should be. APFC is getting 0.95 PF while PFC is getting 0.78 PF. That's how it should be realistically. To measure efficiency you have to look at the manufacturer testing reports, do it yourself if you have the equipment or knowledge (large corporations or industries have engineers with the relevant tools many times), or look towards people wo have reviewed similar items like online websites such as PCPerspective, Anandtech, Toms Hardware, Hardforum, Techgage, Jonnyguru.com and so on. They have the relevant equipment to be able to measure the PSU efficiency at different loads. Inductive or capacitive loads, the efficiency (and power factor) will be fluctuating and never constant, so at 100W DC your PSU might be 74% efficient while at 200W it might be 76% and at 300W it might be 78% (and so on).
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