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CE Risks from Argentina's Drop to 209V?
stm2 asks: "Effective yesterday at 6 PM GMT, the voltage in Argentina was dropped from 220V to 209V (without any warning). The aim of this change is to save power. According to gov' officials, it won't affect domestic appliances. As a concerned IT worker I think some high precision electric devices could be at stake. There is an ongoing national debate about it. Could the technical community at Slashdot give some insights about possible unintended effects?"
Just flip your power supply switches over to the 115V setting and you'll have more than enough power.
because they are in Argentina!
If you have any "precision electric devices" that relies on clean power from the electric company, you have been deceived. Quality precision electronics will always provide plenty of filtering and regulation of their own.
I thought that the main risk during power brown-outs was damage to AC motors from overheating. At least that's what they have mentioned on local radio stations when we've had power shortages.
Mea navis aericumbens anguillis abundat
http://quote.bloomberg.com/apps/news?pid=10000086& sid=a54gb5_g9EIQ&refer=latin_america
Apparently they've put the voltage back to 220 after reaching an agreement to buy power from Brazil.
Who the hell modded as "overrated" something that had not yet even been modded up?
I guess in a micro scale it doesn't save electricity - but in a macro scale several devices don't let more than X Amps go through before popping a circuit breaker, therefor the devices are pulling a constant amperage and saves power.
On a side note - I thought I remembered that the higher the voltage, the more efficient the transmission line, however I know that works for DC (If I recall TVA uses something like 50K Volt DC lines to ship power around) don't know about AC power.
I have mod points and I am not afraid to use them
The funny thing here is that all appliances that regulate the amount of power they consume will continue to consume the same amount of power, but the decreased voltage will cause more power to disappear on the way to the transformers.
As almost anything you have seen on the news from Argentina, reality is quite different.
Electricty companies have been demanding an price increment since 2 years ago, but it would be a very unpopular and "politicaly incorrect" for the government to allow it; so they need to present this as some kind of "emergency".
In the end, companies will:
a) be permited to rise prices about 25%
b) receive a direct subside from government
c) receive an indirect subside form government in form of tax excemptions, "special" fuell prices for generation, "loans" for equipment renewal, etc.
d) all of the above
Already solved with help from Brazil, Bolivia and Venezuela.
Good engineering design requires at least 5% tolerance for voltage differences. That's 11 volts at 220, and 209 should be well within the range of all line powered equipment. You simply can't design a product and expect the voltage to be within 5% regulated value.
Most equipment will run just fine with only 10-20% regulation. The problem with dropping the voltage is that the lower limit is much closer. A 10% device can handle voltages between 198 and 242, but if the utility lowers the voltage to 209, then when it's low by 10% it's at 188v, outside the range of a device capable of operating within 10% of its spec.
The reality is that most electronic devices use transformers and switching regulators to convert line voltage to a much lower voltage. As long as the device isn't consuming its maximum rated current (which will usually be 95% of the time) then it should be fine. The 5% of the time the device is actually using the regulator to its maximum capacity the regulator may fail to provide the voltage level. This erratic behavior will be about the worst you can expect. In most cases you won't even notice this.
The last major effect such a decrease may cause would be to large industrial motors. They are also often specified with a voltage range at which they can provide their rated HP. Lower voltage means a lower output. Those that are specified tightly, or have dodgy starting controls/capacitors may fail to start, but that's an indication of improper sizing/usage and not something that should be blamed on the power company. Of course, at a lower voltage they simply will not perform at the level they do with full voltage, but that is the stated goal for the gov't - to reduce power.
The negative effect for the gov't, though, is the result that people who want or need the same amount of power will simply be pulling more current (amps), stressing out the grid and transformers even more. This will affect transformers and lines that are already operating at their limit, or are about to fail anyway. It's unlikely, though entirely possible, for this action to cost them more than they are saving in the long run.
-Adam
In a simple device, the resistance is roughly constant (up to a certain point). When you decrease voltage, then the current draw actually decrease as well, thereby reducing the power consumption to the 2nd degree.
In your example, a device that draws 440W at 220V (i.e. 2.0A) has a resistance of 0.5 ohms. When you lower the voltage to 109V, that yields
and(Ignoring the fact that 1VA is not quite the same as 1W, due to inductance/capacitance).
My tester shows 213 V right now, at my house in downtown Buenos Aires. As I said in a previous post, this is just PR bs.
Switching mode power supplies take the very large raw input voltage, and draw directly from that input for only a very short time (micro seconds), but several thousand times a second (80Khz). The switch adjusts it draw time to collect the amount of power needed to support the output. If the input voltage drops, the switch adjusts to accept power for a slightly longer time. Really good switching power supplies (not like your PC) will operate on input ranging from DC to several hundred hertz.
- High Tech workers, please say NO to Union Carpenters, their Union sees fit to control our compensation.
Our building 220vac supply actually reads 208vac here right now, so I really don't think 209vac is such a big deal. Most devices have a pretty good tolerance for lower than "adveritzed" voltages.
-psy
Some time ago, voltage was switched from 220V to 230V in Germany (and thus 380V to 400V for three phase current). There was a lot of arguing and lamenting, but nothing interesting happened. Most consumer electr(on)ic devices were rated 220V +/- 10%, while the power authorities guaranteed 220V +/- 5%. Now, devices are rated 230V +/- 10% and power is 230V +/- 5%. So most devices work within their specification, no matter if it is based on 220V or 230V. Some light bulbs rated 220V will light a tiny bit brighter while reducing ther lifetime by a few days.
I don't know how precise Argentina's power authorities can deliver electric power, but I guess they specify it with +/- 5%. They reduced power by exactly 5%, it should not harm most consumer electr(on)ic devices. All heating devices should have no problems, they work with slightly reduced power. Most electronic devices use voltage regulators, so they can accept a wide range of input voltage. Some few devices may need a very precise AC input voltage, but they should already work with some regulation device. The remainder could use an active UPS that generates a very precise output voltage no matter how "ugly" the input voltage is. Wide range power supplies, as used with many modern laptops, accept any input voltage between 90V and 260V, as long as it is AC. They won't have any problems with 230V, 209 V, 135V, 188V, or whatever you find at the next power outlet.
And the best of all: Light bulbs will life longer in Argentina. ;-)
Tux2000
Denken hilft.
I seem to think that good-quality uninteruptible power supplies have some electronic wizardry in them to correct for input voltage. I.e., a UPS would output 110 or 220 volts regardless whether the input voltage is off. Can anyone corroberate this?
Vote in November. You won't regret it.
I could be completely wrong, but in physics class, I seem to remember doing an experiment, to indicate the frequency of the power coming out of the wall was 60Hz.
"When life gives you lemons, don't make lemonade. Make life take the lemons back!" -- Cave Johnson
To really reduce power demand you'd have to cut both the voltage and the frequency, but that would have all kinds of nasty effects on things which depend on a consistent frequency - like standard electric clocks. You also lose the ability to connect to other grids. Needless to say, this is not a popular method of dealing with the issue.
Scientists restrict study to entire physical universe; creationist
Dropping the voltage by 5% does not reduce it to the point where it is out of the standard specification -- at least, not theoretically. Spec allows for as much as 10% variation.
This may, however, cause problems for customers at the end of long distribution lines whose voltages are already below 220. If it is continued indefinitely, it may cause further problems as more customers subscribe and there's less play left in the system.
It is... and in some countries it is 50hz. The switching power supply has four really big transistors and they switch at about 60-80kHz. Each time the transistors switch on or off, they don't care where in the cycle of input power they are. They turn on for just a few micro seconds, then turn off. The power supply gets what ever power it gets in this time frame. The "chopper" which is the heart and soul of the power supply has that "on" interval constantly changing to keep the power level constant. If you really want to know about these things search for "lm3524" that is one of the very basic switching regulator chips. National Semiconductor has good application notes. I used to have an equipment "babysitting" job, and browsed application notes all day.
- High Tech workers, please say NO to Union Carpenters, their Union sees fit to control our compensation.
And your computer power supplies are up to the task?
If not, I would start buying ASAP...
Wars are like a natural wildfire. They devaste, but make room for new growth without hinderance on the past.
Much of Europe and large parts of England were obliterated during WW2. The eletrical infrastructre was all but removed totally. They got the chance to rebuild from the ground up, having the knowledge of what didn't work out so well before.
Contrast this with America, we have lots and lots of very old power systems in place. Yeah, one day maybe we'll get lucky and lose 80% of it, but until then were stuck incrementally upgrading it, and patching it when it's not cost effective to outright replace.
Ahh the downside of not having a war on our soil...
I can live with it.
-Malakai
A Dragon Lives in my Garage
We'll have to rewrite software that hard-coded 220 as a constant!
Having worked in the robotics and automated machinery industries, I would be more concerned about electric motors, especially larger ones. Lower voltage fed to a motor will result in its drawing more current. I also believe they will run hotter. This could spell disaster for companies with lots of old or borderline motors that may now fry. From a residential standpoint, I don't think it will be too good for things like refrigerator compressor motors, AC compressor motors, etc. I don't see the electronics being affected directly too much, especially since switching power supplies used for more sensitive equipment should be able to compensate.
Wouldn't devices just draw more current to run, or run less efficiently?
Venezuela did this recently (during the major strikes)
and one odd side-effect was analog clocks ran slower
than normal. Maybe this answers the question.
As previous posts quite rightly say, the impurities of the mains supply will always be filtered out to the degree demanded of the electronic equipments spec. As for CE, These are the european version of the FCC rules. Again, well designed equipment will 'filter' out variations in the power supply I doubt it will make any difference to the amount of interference generated by electrical and electronic devices. Conversly I doubt their susceptibility will alter either. Now if they had changed the frequency of the supply......
You forgot: Milstein and Favaloro!!!
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