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johanson / Moderator

Mar 7, 2008, 6:37 PM

Post #1 of 14 (5140 views)

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voltage

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As some of you know the line voltage is often between 110 and 120 in the US and Canada and 220 to 240 in many if not all of the countries of Europe.

Here in Mexico it is 127 +/- 10% or about 114 to 140 volts. The actual voltage will vary upon the transformer you have in your neighborhood,

The voltage in my neighborhood many years ago used to be somewhere between 115 and 125 volts. Later we had a new transformer put in and the voltage varied between 135 and 145 volts which was a little too high. After I documented same, the CFE lowered the voltage to a more acceptable 130 to 140 volts which is which is within the 10% range.

In the US light bulbs are often rated to work at 120 volts. Guess what happens when you use that same light-bulb in my house. The filament gets much hotter and therefore the light is much brighter. But of course it burns out in a much shorter period of time.

We had a lecturer at a get-together at the Lake Chapala Society in Ajijic who told us all about fluorescent lights and why they were so much more efficient than incandescent bulbs, something that I think we can all agree upon. He also stated that the fluorescent lights could be purchased in both the US and Mexico and that whether the voltages were meant for the US or Mexico it didn't matter. Because they lasted just as long at his home in Ajijic.

I asked but what is your line voltage? It could make a major difference. He said he didn't know what the voltage was at his home but both those lights meant for the lower US voltage and those meant for the higher Mexican voltage lasted just as long and that it didn't matter where you purchased those bulbs because those meant for the US market where the voltage doesn't go about 120 Volts worked just as well and lasted just as long in Mexico as they did in the US.

That is very different information than I have ever learned, but I have to admit that I am not an expert at fluorescent lighting.

Is it true that unlike an incandescent that would burn out much faster at say 135 volts than the rated 120 volts, that a fluorescent rated for 120 exposed to say 135 volts will not be negatively impacted? It sounds like BS to me.

Any thoughts would be appreciated.

(This post was edited by johanson on Mar 7, 2008, 7:56 PM)

whistler

Mar 9, 2008, 12:59 PM

Post #2 of 14 (5098 views)

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Voltage and Power Issues

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Very helpful post johanson. I live in Morelia and pay careful attention to the electrical issues here because sensitive equipment is at risk, and I have special stereo equipment, computers, power tools, and appliances.

I use 3 APC Automatic Voltage Regulators, simple surge protectors, and a variac to manage my needs. When I am away for an extended time I unplug critical gear.

http://www.apcmedia.com/...STE-6Z7V37_R0_EN.pdf

The link above show the specs for the regulators, and they are invaluable. Amazon has them for around $60 USD.

The regulators can be set to output 120 or 127 volts. 10 amos.

Set to 120 volts out for American products, they handle 85 to 140 volts in (+6%, -12%), ensuring output voltage of between and 105.6 and 127.2 volts.

Set to 127 volts out for Mexican products, they handle 90 to 150 volts in (+6%, -12%), ensuring output voltage of between and 111.8 and 134.6 volts.

For 120 volt power tools I use a variac because I dont want to subject the power conditioners to the voltage spikes and inductances caused by the motors.

I am very happy with these precautions, as I am unwilling to subject my equipment to the unpredictable voltage fluctuations, spikes, and abnormalities that are so common in Morelia. There are too many stories of failed equipment because of improper protection.

I much prefer incandescent light to flourescent and am willing to pay the extra cost, even at the 2.2 peso cost per KWH the local utility charges. If you buy tincandescent bulbs locally (a bit hard to find) they will be designed for 127 volts and they will have a normal life (a bit hard to find). I bring Mogul bulbs from the USA as they are unavailable here, and use either a variable transformer or voltage regulator to step the voltage down if I am in an environment of 130 volts or higher.

It really is worth the trouble to pay attention to the voltage issue because too much equipment is lost from unprotected exposure. People dont understand this until they have lost a computer, amplifier, or television.

(This post was edited by Rolly on Mar 9, 2008, 1:46 PM)

robrt8

Mar 9, 2008, 7:13 PM

Post #3 of 14 (5077 views)

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Re: [whistler] Voltage and Power Issues

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I would guess the filament in incandescent bulbs would be fried by a spike much more easily compared to fluorescent (gas).
There's something else that puzzles me: Modems and laptops have transformers usually rated 110-220v. Why are these still damaged?
While I'm at it, isn't it the transformer and not the modem, for example, that's getting blown? I've ASSumed the output voltage would be pretty regular. Has anyone tried to replace the transformer before tossing the modem/laptop/phone..?

Ron Pickering W3FJW

Mar 10, 2008, 12:33 AM

Post #4 of 14 (5062 views)

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Re: [robrt8] Voltage and Power Issues

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There's something else that puzzles me: Modems and laptops have transformers usually rated 110-220v. Why are these still damaged?

The transformers are 110 AND 220 +- 10%, not 110 TO 220

Getting older and still not down here.

raferguson

Mar 10, 2008, 8:20 AM

Post #5 of 14 (5050 views)

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Re: [Ron Pickering W3FJW] Voltage and Power Issues

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My understanding is most modern power supplies are not limited to just 110V or 220V. Modern 110-220V power supplies, sometimes called "universal" power supplies, are really switching power supplies, not transformers. The label on the power supply for my laptop says "100-240V", and "50-60 Hz". My understanding of a switching power supply is that it basically switches the power coming in at a high rate of speed, and has a small inductor or transformer to help make the conversion. The control circuitry controls the output voltage, and the design allows for a wide range of input voltage. The regulation uses pulse width modulation of the input power, as described in the article below.

http://www.hardwaresecrets.com/article/327

The article does mention a possible voltage doubler circuit, depending on the design, so in that case 140 vs 120 volts might make a difference. However, the same article shows that the label on the power supply mentions 110V and 220V, but does not say "100-240V". I think that when the label says "100-240V", they mean it, that the unit will work within the entire voltage range specified, not just at a couple of limited voltage ranges around the expected nominal voltages. The Wikipedia article on switching power supplies mentions using a variac to determine that a power supply actually operates from 90V to 260V.

The old power supplies, often with big transformers, had an electromechanical switch, and you flipped the switch to select the voltage. In that case, it really was 110V OR 220V, and was not designed to operate at, say, 160V.

My understanding is that modern switched power supplies should not care about the voltage, as long as it is within the overall design limits. Of course, a voltage spike could still fry them, but that has nothing to do with the nominal voltage or the voltage that you would measure with a typical voltmeter.

I suggest looking closely at the label on the equipment power supply, to determine what the power supply is intended to do. If the power supply is labeled with a wide range of voltages, then that tells me that the design should be basically indifferent to the voltages within the specified range. In that case, 140V should be no problem. But voltage spikes could still be an issue, as in the case of lightning.

Richard

http://www.fergusonsculpture.com

robrt8

Mar 14, 2008, 11:50 AM

Post #6 of 14 (5012 views)

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Re: [raferguson] Voltage and Power Issues

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Some more blab about power...

Surge protectors will fail after several surges. One without lights that show proper function are to be avoided.
I'm a little confused about how good it really is to direct a surge into ground, since the neutral and ground are connected at the panel. Computer cases and (I think) the motherboard are grounded as well.
An uninteruptable power supply (UPS) connected to a good surge protector sounds like the way to go. Your devices are not directly connected to power (instead running off the battery). How does that sound?

raferguson

Mar 14, 2008, 9:38 PM

Post #7 of 14 (4995 views)

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Re: [robrt8] Voltage and Power Issues

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The theory behind a surge protector is to keep everything at more or less the same potential. If the entire unit is 500 volts relative to ground, that is OK. The problem comes in when, say the TV or computer AC line is 500 volts, but the cable TV connection is not. If everything is tied together correctly, everything goes up and down together, preventing damage.

You want to reference everything to the same ground. This is one of the reasons that the ground and the neutral are bonded together inside the main circuit panel, per code. The worst would be if the AC power was connected to a ground rod on one side of the house, but the Cable TV was connected to a ground rod on the other side of the house. A good way to smoke equipment. Most people, even those who should know better, tend to think that all ground connections are identical and ideal, which is not the case at all. I have been known to take considerable time to get somebody to understand the implications of a real ground, with its imperfections, vs. the theoretical ideal ground.

A UPS could help, but if the AC goes high, and the cable TV does not, you could still get fried.

The best protection is often layered protection, perhaps using two or three different technologies, to protect the unit.

That said, I have not done much to protect my computer at home, other than a single surge protector on the AC line. I am hoping that the DSL modem is going to protect the computer probably wishful thinking. I should probably go back and figure out how everything is hooked up, and consider if any changes are needed. I should probably have a power strip at the DSL modem that includes the phone line into the house, trying to keep the phone and the AC line at the same potential, as far away from the computer as possible.

Richard

http://www.fergusonsculpture.com

Rolly

Mar 14, 2008, 10:03 PM

Post #8 of 14 (4990 views)

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Re: [raferguson] Voltage and Power Issues

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I connect to my modem via a wireless router. Pretty hard for a problem to make that jump.

Rolly Pirate

S & C

Mar 15, 2008, 4:10 PM

Post #9 of 14 (4965 views)

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Re: [Rolly] Voltage and Power Issues

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Back to the light bulb issue.
I am on the Caribbean coast, just north of Tulum. Before 2001 we had solar power only so I bought a lot of the flourescent bulbs to save energy.
We got CFE power in 2001 and it usually measures around 117.5 Volts.
Back then a friend up the coast in Puerto Morelos told me to get a voltage regulator for my refrigerators because the power will fluctuate a lot. Maybe in his town with old wiring, but on my section of the coast it really doesn't change much at all. On occasion my regulators may be in the trim mode, cutting the power down, but that is not often and is only for a minute or so.
I have since purchased several flourescent bulbs for my house in northern Pa where the power is also quite stable.
What I have found is that the fl. bulbs I use in Mexico seem to last longer than the ones I have in the states.
They say they last for 5 years and I see that in Mexico but not up north.
Don't know why that is but I thought I'd toss my 2 cents worth into the discussion.
Stan

johanson / Moderator

Mar 15, 2008, 6:42 PM

Post #10 of 14 (4956 views)

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Re: [S & C] Voltage and Power Issues

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Thank you all for your input. FUI according to a representative from Seattle City light, accepted voltage there is between 115 and 127 (or my figures 121 volts +/- 5%). Here in Mexico the official voltage is 127 +/- 10% or 114 to 140 volts. If you are lucky enough to have voltage at the low end of the +/- 10%, no big deal. but should you be around 140 volts, look out.

As I believe I mentioned above, in my neighborhood, the voltage approached 145 volts during early mornings. After speaking to the power company, CFE, they turned the voltage down some 4 or 5 volts.

robrt8

Mar 17, 2008, 10:12 AM

Post #11 of 14 (4928 views)

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Re: [raferguson] Voltage and Power Issues

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I'm thoroughly confused now.
Isn't the ground circuit separate from the normal operation of devices?? Most of what I use doesn't have a three prong plug. How can poor ground affect these devices?

delmaracer

Mar 27, 2008, 9:41 PM

Post #12 of 14 (4891 views)

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Re: [robrt8] Voltage and Power Issues

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I use a Panamax M5100 EX line conditioner and voltage regulator http://www.panamax.com/PDF/Datasheets/M5100EX_L548B.pdf
This a a good and reasonably priced device if you have concerns about the power and protecting your expensive electronics. I then use a Monster Theater PowerCenter HTS 1000 to add an additional level of protection. Am I paranoid or what??
From what I can tell, I think I have pretty much insulated my equipment from anyone's errant power. But I have an open mind and want to protect my expensive electronic equipment.
Bob

johanson / Moderator

Mar 28, 2008, 6:37 AM

Post #13 of 14 (4879 views)

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Re: [delmaracr] Voltage and Power Issues

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You wrote "Am I paranoid or what??" The voltage regulator at my home says you are doing the correct thing. However some neighborhoods have voltages much like you have up North. I guess it just depends upon what the average line voltage is in your home.

robrt8

Mar 29, 2008, 8:18 PM

Post #14 of 14 (4844 views)

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Re: [johanson] Voltage and Power Issues

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I've got 127 -. That's actually in the range of 10% or less than 127. Never more than 128 yet detected, using a Mexican voltameter.