Thread: mains voltae two low for desktop

Originally Posted by westom

If it was, you could have challenged it with technical facts. ....
All computers must work just fine even when lights dim to less than 40% intensity. If you think that is rubbish, then quote the ATX Power Supply standard that says otherwise. The standard says voltage can drop even lower and the computer must power up just fine........

Yep it's rubbish!!!

The ATX standard actually states that the power supply must be capable of supplying full rated output power over two input voltage ranges 100-127 VAC and 200 240 VAC and goes on to say that the minimum voltages for startup are 90 VAC and 180 VAC respectively - There Westom, that's technical.

Try as I might, and hardly surprising, I could find no reference in this technical document to the dimming of light bulbs.

There is, however, a noticeable dimming in this thread, and trust me ..it ain't the light bulbs.

Mathuranatha, I have a couple of friends who lived about 10 km out of Dorrigo who experienced similar problems to yours which were mostly solved by investing in a UPS.
I say mostly because even a UPS can't work forever when the supply cuts out completely but they do stabilise and filter the output giving your PC the best possible chance to function correctly.

You may or may not win an argument with your local distribution authority about the quality of your service and in any case, even if you are ultimately proven to be correct, it will take time for them to admit it - so what do you do in the meantime?

If every other appliance in your house is operating as it should, light bulbs included, then I'd be looking at a UPS.

Best of British

Ian

Originally Posted by westom

If it was, you could have challenged it with technical facts. Replying in the tradition of Rush Limbaugh says westom was completely correct and you only did not like it.

All computers must work just fine even when lights dim to less than 40% intensity. If you think that is rubbish, then quote the ATX Power Supply standard that says otherwise. The standard says voltage can drop even lower and the computer must power up just fine.

Are light bulbs dimming anywhere near 50%? Obviously not. If AC voltage is dropping that low, then you have a more serious problem - damaged electric motors or a household wiring problem that threatens human life. AC power utility that is supplying voltage in violation of industry (and maybe legal) standards. AC voltages that are so low as to potentially harm electric motors (as others have noted) remain normal and acceptable voltages for any computer.

If AC voltage is too low for a computer, the household probably has numerous damaged electric motors. Those who know otherwise can only disparage the messenger – do not post concepts, numbers or standards to dispute the reality.

All this waffle about the dimming of lights. And sillier yet, 40% dimming. What apparatus can I use to measure this 40% dimming? I don't think my eyeballs can tell percentages when it comes to the dimming of lights. All I would be doing is guessing.

Having spent about 10 years as an electrical engineer (power), I have never heard of such an unreliable method to determine voltage variation.

Westom, stick to what you seem to do best...that is, talk rubbish but please go & do it somewhere where it is appreciated...like parliament house, USA etc.

When you are ready to get technically real about a problem, you may be worth listening to.

Most UPSes also include software and cable to monitor the quality of the incoming power, and store the results on the PC. Pretty graphs, spreadsheets etc.

IMHO, this would be very useful technical information to help resolve the problems being discussed. It would also (just as an aside) probably solve the problem with the PC.
This sort of thing is what UPSes do.

I know that our ancient microwave pulls a lot of power at startup, because the UPS in another room typically beeps (and shows a drop on a graph) every time the microwave is used.
So, apart from protecting my PC from a voltage/power drop, it is also supplying me with quantitative, objective, technical information.

My 2c?

Go buy a UPS - I had an APC $1200 one which died just out of warranty, and the repair quote was more than replacement. Since then, my $300?? UPS from Jaycar has been a work-saver on 5 occasions over 4 years.

Cheers,
Andrew

Originally Posted by Ian Smith

Try as I might, and hardly surprising, I could find no reference in this technical document to the dimming of light bulbs.

Did your light bulbs dim anywhere near to 40%? No? Either measure with a scope or multimeter. Or see voltage is sufficient by simply viewing incandescent lamps. Using basic electrical facts (including your numbers), it was dumbed down. Simply look at light bulb brightness.

Of course some buy power supplies that do not even meet minimal requirements from 40 years ago. Save $20 or $40 on the supply. Then pay $150 for a UPS to solve the resulting problem. That proves the UPS is needed? Only to those who avocate a UPS as a magic cure..

The typical UPS does nothing to stabilize voltages. It simply switches to battery when voltages drop somewhere about half way to too low. It also does not filter anything. The typical UPS connects AC electric directly to the computer when not in battery backup mode. Filtering is close to zero. To get a UPS that does what you avocate costs $500 or higher.

If every other appliance in your house is operating as it should, light bulbs included, then find and fix the computer defect.

As BarryWhite noted, "if you are getting low voltages it can burn the motors out." Instead of a UPS to cure symptoms, fix the problem.

As bonk noted, "You could replace the desktop power supply with a universal one". Especially when the power supply (not AC voltage) is the problem.

If a microwave oven is causing voltage to drop so low as to interfere with a computer on the same circuit, then get the building wiring fixed. No appliance should reduce voltages that low is the wiring is minimally acceptable.

Ah Dumbed down - yes I can how you are well equiped do that.... oohh must type quickly ....light fading fast .... oooh ohhh omigosh 39% must fin...ugh..

Originally Posted by westom

Of course some buy power supplies that do not even meet minimal requirements from 40 years ago. Save $20 or $40 on the supply. Then pay $150 for a UPS to solve the resulting problem. That proves the UPS is needed? Only to those who avocate a UPS as a magic cure..

The typical UPS does nothing to stabilize voltages. It simply switches to battery when voltages drop somewhere about half way to too low. It also does not filter anything. The typical UPS connects AC electric directly to the computer when not in battery backup mode. Filtering is close to zero. To get a UPS that does what you avocate costs $500 or higher.

If every other appliance in your house is operating as it should, light bulbs included, then find and fix the computer defect.

As BarryWhite noted, "if you are getting low voltages it can burn the motors out." Instead of a UPS to cure symptoms, fix the problem.

As bonk noted, "You could replace the desktop power supply with a universal one". Especially when the power supply (not AC voltage) is the problem.

If a microwave oven is causing voltage to drop so low as to interfere with a computer on the same circuit, then get the building wiring fixed. No appliance should reduce voltages that low is the wiring is minimally acceptable.

Westom, I'm sick of this crap ...

The part of the ATX specification refered to by my namesake, paraphrased, says "if the input voltage is below 200 or above 240 VAC, don't expect your computer to work"

BTW, my understanding is that although the "official" supply standard is 240V, in practice the supply authority only ever aims to deliver 230V
and 230 less 15% is less than 200

the OP's problem as described is
the OP lives some ways out of town, at some distance from the nearest transformer, in an area where electrical loads have increased ("more people living on the property")
computer runs OK late at night when other elec loads in the area are low
computer runs OK in town,
computer runs OK if powered via a 12V to 240V inverter driven by a battery charger

The problem — the computer doesn't work when the electrical load in the neighbourhood is high

egad, the problem looks a lot like a supply problem, which is not that unusual on rural residential blocks

how this translates to an issue with the quality of the fitted ATX power supply eludes me.

what can the OP do?
1) complain to, and try to negotiate with, his electrical supplier (which is almost certainly a state owned monopoly which is being readied for sale) — you're welcome to hold your breath, but I've better things to do

2) install a small UPS which will at least allow the OP to keep the PC running and which will also allow a controlled save and shut down next time the wind blows really hard and the power line trips


A UPS will allow the OP to keep his PC running, but he should also followup with his supplier because of the damage low voltage is likely doing to his other electrical equipment


Westom,
rather than quote esoteric ATX specs, what is your suggestion for the OP?
and how will the OP know that what he is paying for is what he asked for?
and if you were in a similar position — some distance out of town and the end of a power line that needs enhancement (based on other posts on this forum, for the sake of the discussion let's assume the enhancement would cost in excess of $50,000) — how long would you expect to have to wait before it was done?

I'm not taking any sides here or offering a solution as I don't have one, but I'd like to point out the westom is from the US going by his location stats and the he may not know that Australia has different voltages and also that there is vast distances between power stations which can lead to these problems and it can cost huge dollars to get power supply to areas.

In case people didn't know:

1.6.2 Supply characteristics.
NOTE: The nominal voltage and tolerances for low voltage supply systems
and electrical installations are—
(a) for Australia, 230/400 V +10% to −6% (in accordance with AS 60038);


3.6.2 Value.
The cross-sectional area of every current-carrying conductor shall be
such that the voltage drop between the point of supply for the low
voltage electrical installation and any point in that electrical
installation does not exceed 5% of the nominal voltage at the point of
supply.

Let's stop all this complete & utter nonsense about the dimness of lights.
The two "Ians" are spot on with their conclusions/suggestions.

Originally Posted by DJ's Timber

... he may not know that Australia has different voltages and also that there is vast distances between power stations which can lead to these problems and it can cost huge dollars to get power supply to areas.

Differences are minor and irrelevant to the symptoms. Standards such as 5% voltage variations are universal among civilized nations. We work with all those voltages - and others. Voltages that vary so much as to damage appliance electric motors must not exist. Computers will work normally even when those voltages drop so low (ie 180 volts) as to be harmful to motors. Our equpment had to work at all those voltages - and others.

Computers use 115 volts or 240 volts to create over 300 volts inside the supply. Only difference is how that 300+ volts is created. Internal voltages (3.3, 5, 12) are created from the same 300+ volts – in every country.

How often do your incandescent bulbs dim to 40% intensity? If bulbs dim to anywhere near 40%, then you have other and more serious problems. Could be defective wiring that has become a fire threat. Or a utility that is violating standards. If bulbs are not dimming to 40% (and a UPS 'fixes' power), then the problem is more likely a defective computer. Fix the problem.

Defective as in a computer assembler who bought a power supply only on dollars and watts. Devoid of minimally sufficient knowledge. One needs no electrical knowledge to pass the A+ Certified Computer Tech tests.

bonk suggested, "You could replace the desktop power supply with a universal one". A universal power supply works on any power in any country; on any voltage from 90 to 265 volts. A supply replaced because it was defective when it was purchased.

What would the UPS do? $150 to fix a problem because the computer assembler saved $20 on a power supply? Cure the symptom - ie defective and dangerous household wiring? An incandescent bulb is an obvious measuring device that anyone can use. Does that light bulb dim to anywhere near to 40%? If yes, then a problem exists elsewhere. Solve the problem. A UPS would only cure symptoms. To computers, 120 volts or 230 volts makes no difference since all AC mains power is first converted to 300+ volts.

Originally Posted by westom

An incandescent bulb is an obvious measuring device that anyone can use. Does that light bulb dim to anywhere near to 40%? If yes, then a problem exists elsewhere. Solve the problem.

westom, please give up this inane idea about the lamp. Just drop it! Everything else you say is good info. You lose credibility when you rave on about pecentages of dimming. There is no person on the planet who is capable of accurately telling the difference between 30%,40% & 50% dimmed.

Originally Posted by elkangorito

There is no person on the planet who is capable of accurately telling the difference between 30%,40% & 50% dimmed.

And again, nobody has to. Either light is closer to 100% intensity, or it is closer to 40% intensity. If light is at 30%, or 40% or 50% intensity- that is about 40% intensity And problems exist on the AC mains - voltage is excessively low. Solve the problem. Don't cure symptoms.

40% light intensity was not posted for your benefit. How to identify and solve problems quickly was posted for those who would rather learn from an engineer with a few generations of experience. Your posts are only a nuisance to others who would rather learn new tricks.

If line voltage does not cause 40% incandescent bulb dimming, then a most likely culprit is a computer defect. A problem more often seen where computer assemblers buy power supplies only on dollars and watts. They do not even demand numeric specs - just buy on price.. Then recommend a $150 UPS to fix that $20 defect.

Dear oh dear oh deary me!

A filament lamp's resistance increases with temperature so the V/I curve is very non-linear. Half the voltage will actually give about 65% of the current so the output power will be more than a quarter of its full output. 220V bulbs that operate on 120V, actually burn quite bright (and for a long time).

Give it up westom before your become a complete buffoon. At the moment, you are about 80% on my buffoon scale...or maybe my perception of "buffoonism" is different to that of others.

Originally Posted by westom

To repeat it again: electronics must work just fine even when the dims to 40% intensity.

This is incorrect. The 40% lamp intensity discussion is completely meaningless. My experience at work is that some electronics, even so called brand names like Hewlett Packard, will fail when the AC supply voltage drops by as little as 15% below specifications. We have frequency generators at work that can only handle +/-5% variation in input voltage so we have everything in our labs on a 3 phase UPS.

Electronics can also "age" and become less tolerant of input V variations as they get older. A few years ago we had a dishwasher that had run fine from new for 8 years but it then started to fail intermittently every couple of days. Sometimes it would start OK but then it would not finish it's cycle. I opened it up to take a look but a large section of the electronics was embedded in a set of sealed epoxy blocks so there is not much one can even look at.

Reluctantly I took it in to a service centre where it ran flawlessly for a week. Brought it home - same problem - took it back , no problem - took it home same problem. The techo suggested there could be a voltage problem because they did have some problems with this model even when new when they were used in the country where the mains would sometimes drop below spec but he couldn't see how this would be a problem with an inner city location.

So I hooked up a logging voltmeter to the mains and quickly worked out that it would not work when the input V dropped below 234V (NB this is still within supply spec). I then hooked it up to a VARIAC (variable voltage transformer) and found if I supplied it with mains V + an extra 5V it would work just fine. Since the repair involved a complete replacement of the electronics control circuitry ($180!) so I just left it running on the VARIAC, but after a few months it needed a few more volts on top of that, after one year it needed an extra 20V which was starting to become dangerous so we bought a new one.

Another time this happened recently was on a 2.5 year old flat panel display at work which worked intermittently at mains but would run fine on 250V! Like the dishwasher it was probably just a faulty voltage regulator.

Originally Posted by westom

And again, nobody has to. Either light is closer to 100% intensity, or it is closer to 40% intensity. If light is at 30%, or 40% or 50% intensity- that is about 40% intensity And problems exist on the AC mains - voltage is excessively low. Solve the problem. Don't cure symptoms.

40% light intensity was not posted for your benefit. How to identify and solve problems quickly was posted for those who would rather learn from an engineer with a few generations of experience. Your posts are only a nuisance to others who would rather learn new tricks.

If line voltage does not cause 40% incandescent bulb dimming, then a most likely culprit is a computer defect. A problem more often seen where computer assemblers buy power supplies only on dollars and watts. They do not even demand numeric specs - just buy on price.. Then recommend a $150 UPS to fix that $20 defect.

And what if a person is running compact flourescent light bulbs as is the standard in Australia, now that most incadescent have been phased out. I'm not a sparkie, nor do I understand a lot of the technical jargon being used here but I think you're here Westom.