Slight OT: power consumption of PC PSUs

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On Mon, 22 Sep 2003 10:12:50 +0100, froggers wrote:

400W for 6hrs is 2.4kW/hrs, ah I guess your doing a x4 to get the "whole house off" consumption for a 24hr period.

We use about that amount per day, cook by 'lectric but have rather too many incandescant lights on from 0700 to 0100ish which costs approx 30/qtr... Must replace some with CFLs I reckon they'll pay for themselves within 2 quarters if not 1.
Base load when I very quickly checked it one evening was about 700W (+/- 200W) thats with around 400W of lighting on. Similar stuff on to yourself so 400W average base load probably isn't two far from the mark.
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On Mon, 22 Sep 2003 18:50:09 +0100, Witchy wrote:

Far to many variables. Soem kit in "standby" takes just as much power when "on". Much easier to read the meter when you go to bed and when you get up noting the times as well do this for a week. Then use some simple maths to work out how much power you have used each night and an average.
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On Mon, 22 Sep 2003 22:03:56 +0100 (BST), "Dave Liquorice"

maths! eep :)
witchy/binarydinosaurs
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Andy Wade wrote:

I love speculation/guesstimations 8-)
There is little change in the PF with load. I guess the PF is to a large extent an inherent property of the of the design of the PSU. Presumably the PF is _leading_ for SMPSs. The PF of the SPeakers is doubtless a X-former hence its poor PF.
You have only got to see the amount of fins and fan(ette)s in a newer sys box to realise where the energy is going.
I guess that although the circuits are physically smaller there are many more of them (does this work out as proprtional to the area of the silicon in the sys box?). Not that much more? Perhaps the difference is that the circuits are also switching much faster in the newer box.
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Ed Sirett wrote:

Its that basically. CMOS certainly had very liitle current draw in ON or OFF states - not sure what technology is used - but anyway, the current all goes to charge and discharge the inherent micro capacitors in the chips. And it has to go through the transistors to do it, so they get effin hot.
WE never put heastinks onm 2Mhz Z80's mate.

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"Ed Sirett" wrote in message

Yes, although the PF will, in general, tend to get worse for light loads.

The non-unity PF for SMPSs is mostly due to harmonic currents, rather than phase shift. Another way of looking at it is that the spiky current waveform that you get with a low impedance source (the mains) feeding a rectifier and capacitor input filter means that the RMS input current is higher than you'd need to feed the same average power to a resistive load, hence the VA is higher than the watts - i.e. the PF is less than unity.
Of course it's not quite so simple in practice nowadays because the EMC regulations effectively require SMPSs over 50W to have power factor correction.

Yes - it's a low-cost wall-wart designed only for low initial cost, with no consideration whatever of efficiency or running cost. I was contemplating throwing it away and extracting the 12V supply for the speakers from the system unit.

Other things being equal, the power is proportional to the clock frequency and to the square of the supply voltage -- hence the drive to lower and lower chip supply voltages.
--
Andy



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Negligable leading factor, but mostly it isn't due to phase shift.

I would imagine a transformer with little/no secondary load, which looks like an inductor across the mains.

Yes, and there are so many more of them because in addition to the silicon getting bigger, the individual circuits get smaller.
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Andrew Gabriel

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Andrew Gabriel wrote:

copper losses of the wall-wart. There's nearly 4 quid a year to be saved by powering the speakers from elsewhere.
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On Tue, 23 Sep 2003 19:26:55 +0100, Ed Sirett wrote:

CPC have an ISA bracketed(*) card that will provide a regulated supply at a range of voltages and both polarities for less than a tenner. It gets its power from a drive power connector. Fitted to a couple of the machines here, speakers go on/off with the PC and there is one less wall wart.
(*) It doesn't connect to the slot edge connector so will fit a PCI based machine but the card is mounted on the other edge of the bracket compared to PCI so one has to watch where things meet or get close.
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writes:

Are you saying that an ordinary wall-wart costs that much to run?
David (counting up the number of the damned things he currently has permanently plugged in around the house...)
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"David" wrote in message

Most of them aren't as bad as the one in question: 1.5 to 2 watts is more typical. 2 W times 8760 hrs/yr is 17.5 khW/yr, which would cost you about 1.20 per year at 7p per kWh.
--
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My washer states :-
Consumption in kWh - 0.95 Running time - 1h58m
So only ~14p per wash? I figured it would be much higher than that.
-- S i g n a l @ l i n e o n e . n e t
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Darn, can't find the rest of this thread. Spent a bit of time last week putting together notes for our first year computer class and I was listing modern CPU's.
THe latest Pentium 4 which is being rushed through to compter with the new 64bit Athlon processor is pumping out a tad under 100W of heat!
That requires a serious heat sink/ fan to say the least.
Anyway, thats even more off topic so I'll just get me coat.
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back-of-the-envelope approximation, that's a tad over a week (200 8*25, but only 24h and 7 days in a week), so let's say there's 50 such periods in a year (round number less than 52 rounding in the right direction to compensate for the overguesstimate previously). So the wallwart will eat about 50 Units in a year; at 7p a unit that's 3.50, at 8p it's the 4 quid mentioned. As others have said, 5W is more than most wall-warts will use when doing nothing, but poorly-designed or higher-output ones could pull this much. (One comprehensive report with per-appliance breakdowns and considerations for overall generation and equipment-production policy comes from the Land Down Under, at http://www.energyefficient.com.au/standby/download-sb2.html The summary figure there is "Average standby and miscellaneous consumption was 86.8 Watts... in Australia this equates to 11.6% of [year] 2000 residential electricity use".)
Powering *off* your a-v kit, multiple little peripherals, and the like is a Win in electricity bills and overall energy consumption (the latter is muddied in a temperate/cold climate as effectively all the "wasted" power goes to warm up the house, decreasing the amount of deliberate heating you have to do, most typically from a cheaper-to-you source - gas CH - but one which contributes a midgeon more to carbon dioxide emissions than the balance of electricity generation sources which include nuclear and hydro-electric). For kit which spends a small part of its time being actively used it's a win in life expectancy too; for frequent-use items we're into the more complex tradeoffs about switching surges versus resting...
Stefek
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snipped-for-privacy@hp.com wrote in message wrote:

Hmm - just musing on this; when I set up my PC workstation I extended a ring main within a stud partition to provide 3 double sockets side-by-side(not very accessible, under the desk) for all the computer gear; thus I have wall-warts there for printer, broadband network router, speakers, emergency modem, phone charger... so it would be nice to be able to just switch off all 3 sockets via a wall switch at desktop height.
How could I do this? The 2 ring main cables come down from the ceiling within the same section of the partition. *Theoretically* I could reconnect the ring without the sockets there, and re-wire them as a fused spur; however that would contravene regs wouldn't it. Three fused spurs, with separate switches maybe? Yuck. Surely there's a proper, neater way?
TIA David
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David wrote:

Take the sockets out of the ring and connect them as a single spur to a switched fused outlet which is in the ring. Having the fuse makes this OK since the cable of the spur is now protected from overload by the fuse.
--
Cheers,

John.

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David wrote:

A good rule of thumb is that 1W on 24/7 for a year is around 1 quid. 1Wyear is about 31MJ roughly 8 kWhr. i.e about 60p So I'm a bit out but in the right area.
-- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at www.diyfaq.org.uk Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
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wrote:

It's easier to work out 1W for 24hrs/day for 40 days being more or less exactly 1kWh. Multiply by 9 and you have 1W for 360 days equating to 9kWh. 60-70p sounds about right.
--
John
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Now THAT looks like a handy device! My whole reason for asking the question in the first place was the higher electricity costs associated with a much bigger house than the last one despite us using pretty much the same stuff here. The only things we could come up with were the extra PCs being used, but looking at Dave Baker's post below they can't be the whole reason.....nice to be able to measure pretty much everything else.
cheers
witchy/binarydinosaurs
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On 21 Sep 2003 15:15:44 GMT, snipped-for-privacy@aol.comma (Dave Baker) wrote:

As little as that? Hmm, that averages out at less than 25 per quarter then, which doesn't explain the high bills we're getting....I wonder if the old washer and dishwasher were using more power than the ones we left at the other house......hopefully that's academic since we've got AAA rated stuff now as well as a B rated fridge/freezer. If the bills don't come down in price I'll be stumped!
cheers
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