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