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?"

Comments

No problem at all.

[Anonymous Coward]

Just flip your power supply switches over to the 115V setting and you'll have more than enough power.

Many wanted to reply, but couldn't...

[Anonymous Coward]

because they are in Argentina!

Regulation.

[computersareevil]

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.

Re:Regulation.

[jungd]

Surely, this is only true in countries where utility power is unreliable (like the US)?

I moved to the US five years ago and was initially amazed that someone had experienced a power outage in their lifetime! - After realizing they weren't joking I though it must have been a pretty unusual circumstance - like a major earth quake or something. First time I'd ever heard of surge protectors in power strips too - yikes! - doesn't give a good feeling about the power.

Of course, now I know better, that the electrical systems of building and power distributions systems are just extremely poorly engineered due to lax regulations and cost pressures (which might explain cheap electricity too). First time I'd ever seen electricity cabling strung on posts above ground on the street sides - hardly surprising that it can be effected by weather.

Since I've been living in TN, I've experienced 2 power outages due to thunderstorms, and now keep a set of candles in the kithen drawer.

I've even done some re-writing of light fixtures in our house myself - no degree/license required!

So, perhaps the US has traded for relaxed regulation, DIY wiring & cheap electricity at the expense of unreliable power & telecoms and higher cost/complexity of consumer applicances to compensate.

In short, I guess I'm suggesting that assuming that all electric devices are built to handle unreliable power (brownouts, spikes etc.) is perhaps country specifc.

Re:Regulation.

[HeyLaughingBoy]

Surely, this is only true in countries where utility power is unreliable (like the US)?

No, truly precision devices (by that I mean measurement instrumentation) can not rely on the powerline voltage remaining within 0.1% of spec as a cheap, off the shelf voltage reference chip can.

In short, I guess I'm suggesting that assuming that all electric devices are built to handle unreliable power (brownouts, spikes etc.) is perhaps country specifc.)?

I sure hope not. Would be pretty poor practice on the part of the engineer who designed it to not account for voltage fluctuations. The reality is that the real world outside a computer (actually the +5VDC voltage inside a computer is pretty ugly) is messy. Refrigerator or A/C compressor switches on == big dip in line voltage, lightning strike a few miles away induces big currents in the line. No engineer in his right mind would power electronics directly from the AC line without some sort of filtering/isolation.

Re:Regulation.

[foooo]

No need to be an such an ass to your "host" country. Most problems of this nature in the US are due to having a much larger land mass. Additionally populations (on average) in the US are much less dense than their northern european counterparts making it much harder to support infrastructure of this kind.

US power companies are regulated... but they don't have the advantages of government run power companies. IE they can't just dip in to the general fund if the feel like they want to make some infrastructure improvements. They actually have to justify it.

I live in a reasonably dense area and my power goes out maybe once every two years. When I lived out in a more rural area my power went out several times a year... the further out you are the less dense the population and the more likely your power will go out.

Astoundingly Americans have learned to deal with it. Frankly it's not worth it to me to pay more to have more reliable electricity. If I want more security I'll make sure I have my own means of power production or UPSes or something.

I would be interested to know the "real" per capita expenditures for electricity in your previous country. I'd also be interested to know the "real" per kilowatt hour price. These numbers would have to include government subsidies.

I think there are some government subsidies for power companies in the US but I would assume (I'm not certian) that they are lower than your previous country of residence.

As for doing your own wiring while you can certianly hire electricians in the US and many new construction projects require inspection from an electrician before permits are approved/issued.

Frankly I'm shocked that other countries wouldn't allow citizens to do their own wiring. Not only is it a freedom issue but a phenomenal waste of money to always have to pay someone else to do work that just about anyone could do.

Additionally European electronics certifications are much more stringent than those in the US. So even if the power is more reliable the government will make darn sure the end user devices are still very robust... and therefore they should cost as much or more than their US counterparts.

I can't really speak for Japan or other Asian/African nations since I just don't know very much about their electrical systems.

~foooo

Re:Regulation.

[squiggleslash]

None of the UK has weather like the SE USA does (yes, I've lived in both places... although I was very, very young when I lived in the UK). We have far more thunderstorms and tornados than just about anywhere else on the planet.

Interestingly, Britain is, according to a survey I can't find right now, the place in the world with the largest number of reported tornados for its size. Of course, there are tornados and there are tornados, and it's relatively rare for what passes in Britain as one to be destructive - though not unheard of (as people in Reading, Berks can tell you about two years ago.)

Hurricane-strength storms hit Britain every five to ten years - the last one was a couple of years ago, November 2001 IIRC. British people are so used to them they never think of them in those terms, indeed Britain generally plans for them - count the wood:stone ratio of homes in Britain compared to the US. Fortunately Britain's coastline is dominated by cliffs, otherwise it'd see more damage than the occasional wall collapsing or roof being blown off.

AC Motors

[Detritus]

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.

Back to 220

[crow]

A quick check at Google News revealed:

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.

How does dropping voltage "Save Power"

[MerlynEmrys67]

I would figure your device needs 440W. At 220V you pull 2A to get that. You drop the Voltage to 205V and your device now pulls just under 2.15A.

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.

Re:How does dropping voltage "Save Power"

[englhard]

I'd be greatly surprised if power lines were transmitting DC. One of the main, historical advantages of AC is that it is much, much easier to transform voltage up and down, making transmission viable.

Re:How does dropping voltage "Save Power"

[Aniquel]

Hm, IIRC, don't think it works like that. You're assuming that a device draws enough current to meet power requirements (P = VI). However, in this case V is fixed, and I is determined by resistance (R). Remember V = IR? So, the effect of fixing V at a lower value is: 1) I goes down according to V = IR, and 2) P goes down because of the new (lower) I in addition to the lower fixed V, according to P = VI.

Re:How does dropping voltage "Save Power"

[stevew]

Local power in the US is sent via High Voltage AC. Very few connections in the US are DC - but there is at least one I know of. The Northwest Intertie used to ship power between Washington state and Southern CA uses a High Voltage DC. There is a simple physical reason why - it is about a 1500 mile trip, i.e. roughly 1/4 wavelength at 60Hz. They went DC because of that little feature.

The southern terminus of the transmission facility is visible off of I5 as you enter LA from the North.

Just PR bullshit to rise prices

[DeepBlueDiver]

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

Re:Just PR bullshit to rise prices

[cpeterso]

but it sounds like the Argentina gub'mint has price caps that prevent the producers from reaping the true value opportunity of the power market. The price caps to ensure "cheap" power are CREATING power shortage! Higher prices (or lawsuits) are sure to follow.

Re:Just PR bullshit to rise prices

[BCoates]

We had/have a similar problem here in the California Republic, and solved it by destabilizing our leftist government and letting a semi-rightist austrian strongman rise to power in a popular coup.

Well, perhaps not solved the problem, but when the power goes out this summer, we can intimidate our neighbors and have them send us power so that we don't come in an take it--I mean, have you seen that guy's biceps?

problem solved!

[LordAlpha]

Already solved with help from Brazil, Bolivia and Venezuela.

Good engineering design...

[stienman]

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

Ohms law basics

[Tor]

I would figure your device needs 440W. At 220V you pull 2A to get that. You drop the Voltage to 205V and your device now pulls just under 2.15A.

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

(209V/220V)*2.0A = 1.9A

and

209V*1.9A = 397W

(Ignoring the fact that 1VA is not quite the same as 1W, due to inductance/capacitance).

I read 213 V right now

[DeepBlueDiver]

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.

Re:I read 213 V right now

[TBone]

That's funny, my improvised fork testing device shows....*BZZZZZZZT*

switch mode power supply immune 2 small v change

[ElectricRook]

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.

Re:"Save power"?

[Mr. Slippery]

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

True, but other devices act more like simple resistors, and if less voltage is applied they will consume less power. You PC will self-regulate, but your lightbulbs will get dimmer.

I'll bet that light bulbs and other "simple resistor" devices outweigh PCs and self-regulators several times over.

Germany: 220V - 230V

[Tux2000]

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

Re:Germany: 220V - 230V

[funky womble]

In UK, when EU voltages were 'harmonised', the normal supply at 240v was already within the permitted range, so only the nominal voltage was changed to 230v, the actual supply voltage remained at 240v. See this article for more details and potential problems of this approach.

Re:No big deal

[GigsVT]

208 vac is a manifestation of a 3 phase system, 120V to the ground, 208 volts between legs.

For some devices, it doesn't

[Spamalamadingdong]

Induction motors are one good example. An induction motor's speed is determined mostly by the drive frequency, not the applied voltage. Lowering the voltage can affect the slip between the rotor and the stator field, which in turn affects things like the magnetizing current draw. If the voltage drops too low the stator field cannot transmit enough torque to keep the slip below the torque peak, and the motor stalls; a stalled motor has no cooling unless it has an external cooling mechanism, so it can overheat easily and destroy itself. Thermal cutouts are supposed to prevent this, but wiring stands up best if it is not subjected to overheat stress.

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.

Re:If my thinking is right (and it never is)

[MajorDick]

Damm I knew I should have left work like 4 hours ao...damm clocks slowing down....