Electronics > Projects, Designs, and Technical Stuff
switching-PSUs: why can't you usually exceed the 50% of declared power?
Alex Eisenhut:
--- Quote from: tautech on May 24, 2020, 01:55:10 am ---You cannot assess a PSU with light bulb loads OR its capability if loading only one rail !
Each output can only be loaded to its rated output and several output loads may be necessary to reach its full rated output in watts.....but specs may be only in watts consumption NOT total output.
Further, tungsten bulbs have high initial current draw until the filament reaches operating temp where its resistance is much lower than when cold. This inrush current could send the SMPS into shutdown.
All ^^^ traps for the unwary !
--- End quote ---
Speaking of traps, I think you meant the resistance is much higher than when cold. ;)
engrguy42:
--- Quote from: coppice on May 24, 2020, 01:05:37 pm ---
--- Quote from: engrguy42 on May 24, 2020, 12:37:52 pm ---FWIW, it's a myth that higher efficiency power supplies save you a lot of money on your electric bills. Do the math.
--- End quote ---
For most people moving from an 80% efficient supply to a 90% efficient supply in their PC will not save much in electric bills, because their PC is only working hard for a small percentage of the time. However, for server, telecoms and other high power applications running flat out 24 hours a day every extra percent of efficiency brings a big enough reduction in power bills to justify significantly higher complexity in their power supplies. Try looking at the materials used to promote multi-kilowatt supplies in the 95% to 97% efficiency area. Its all about cost breakdowns over the life of the equipment.
For consumers a shift from 80% efficiency to 90% efficiency is not useless. Halving the supply's heat output helps compact machines to run cool with a very quiet fan.
--- End quote ---
If you look hard enough you can always find an exception to anything. Of course, commercial and industrial usage is ENTIRELY different. We're talking average users, who don't know any better. Commercial and industrial users know exactly what it's costing them.
And it's easy to make vague generalities like "lower heat is better", but in practical terms it's likely irrelevant in terms of effects on actual service life, etc.
wraper:
--- Quote from: PKTKS on May 24, 2020, 12:55:28 pm ---This is a total wrong argument. The savings on the bill
promoted by such "ratings" 80% 90% gold plus shit are garbage.
Those PSUs are targeted to high end PCs where you use
hungry power GPUs which waste awesome 700W of true power
plus ownership costs.
SOHO and POS are well below 300W and the cost focus
is more on hardware wearing out soon than the mains bill
--- End quote ---
Total bullshit. Even if computer consumes only 100W, 10% consumption difference is a big deal. And estimation in my previous post is based on such figure for office use. If there is high-end GPU and frequent gaming involved it becomes even more noticeable and more expensive PSU may pay off in less than a year.
Monkeh:
--- Quote from: engrguy42 on May 24, 2020, 01:10:33 pm ---And it's easy to make vague generalities like "lower heat is better", but in practical terms it's likely irrelevant in terms of effects on actual service life, etc.
--- End quote ---
However the difference in component quality between the low efficiency garbage certain people are promoting and a decently made and efficient supply is relevant in terms of service life.
engrguy42:
--- Quote from: wraper on May 24, 2020, 01:14:58 pm ---
--- Quote from: PKTKS on May 24, 2020, 12:55:28 pm ---This is a total wrong argument. The savings on the bill
promoted by such "ratings" 80% 90% gold plus shit are garbage.
Those PSUs are targeted to high end PCs where you use
hungry power GPUs which waste awesome 700W of true power
plus ownership costs.
SOHO and POS are well below 300W and the cost focus
is more on hardware wearing out soon than the mains bill
--- End quote ---
Total bullshit. Even if computer consumes only 100W, 10% consumption difference is a big deal. And estimation in my previous post is based on such figure for office use. If there is high-end GPU and frequent gaming involved it becomes even more noticeable and more expensive PSU may pay off in less than a year.
--- End quote ---
Again, do you have ACTUAL numbers to support this, or is it just vague generalizations based on personal belief?
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