surge suppressor voltage limit

snipped-for-privacy@ipal.net wrote:


A surge is, by definition, a very short event - certainly well under a cycle. The next most damaging surges, after lightning, are generally from utility switching. Crossed power lines like Hanford are far too long duration and are "temporary overvoltage" or maybe "swells" (up to a few seconds).
MOVs are rapidly destroyed by long duration events. Martzloff has written "in fact, the major cause of [surge suppressor] failures is a temporary overvoltage, rather than an unusually large surge."
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| snipped-for-privacy@ipal.net wrote: |> |> |> I notice from videos of the 33kV surges that happened to homes in Harford |> |> county MD, severe damage levels was propogated into at least the inside |> |> breaker panels. If the arcing at the meter and the service cable does not |> |> completely quench the surge, and it gets to the panel and destroys that, |> |> then why not also go beyond and take out appliances? The question is just |> |> how much voltage reached each point. Arcs have a voltage drop, but they |> |> do also have impedance (inductance). So they cannot completely clear a |> |> differential surge. Clearly the arc at the meter did not clear the surge |> |> since there was more surge damage at the panel. |> | . |> | It was not a surge. |> |> So do you classify anything happening to utility equipment as NOT a surge? | | A surge is, by definition, a very short event - certainly well under a | cycle. The next most damaging surges, after lightning, are generally | from utility switching. Crossed power lines like Hanford are far too | long duration and are "temporary overvoltage" or maybe "swells" (up to a | few seconds).
My definition of a surge is bigger than your definition of a surge!
| MOVs are rapidly destroyed by long duration events. Martzloff has | written "in fact, the major cause of [surge suppressor] failures is a | temporary overvoltage, rather than an unusually large surge."
Then they need to design for that.
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snipped-for-privacy@ipal.net wrote:

. My definition of surge is industry standard including the IEEE. It works better if you use the same definitions other people do. .

. As has been covered in this newsgroup before, it is not practical to protect from temporary overvoltage with MOVs. Only practical protection I know of is to disconnect from the source. Depending on how high the overvoltage that may not work well.
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| snipped-for-privacy@ipal.net wrote:
|> |> |> |> |> I notice from videos of the 33kV surges that happened to homes in Harford |> |> |> county MD, severe damage levels was propogated into at least the inside |> |> |> breaker panels. If the arcing at the meter and the service cable does not |> |> |> completely quench the surge, and it gets to the panel and destroys that, |> |> |> then why not also go beyond and take out appliances? The question is just |> |> |> how much voltage reached each point. Arcs have a voltage drop, but they |> |> |> do also have impedance (inductance). So they cannot completely clear a |> |> |> differential surge. Clearly the arc at the meter did not clear the surge |> |> |> since there was more surge damage at the panel. |> |> | . |> |> | It was not a surge. |> |> |> |> So do you classify anything happening to utility equipment as NOT a surge? |> | |> | A surge is, by definition, a very short event - certainly well under a |> | cycle. The next most damaging surges, after lightning, are generally |> | from utility switching. Crossed power lines like Hanford are far too |> | long duration and are "temporary overvoltage" or maybe "swells" (up to a |> | few seconds). |> |> My definition of a surge is bigger than your definition of a surge! | . | My definition of surge is industry standard including the IEEE. It works | better if you use the same definitions other people do.
My interest is in protecting against that which I have termed "surge" under my definition. If you have a better term to use that covers my definition, please suggest it. Until then, the only term I have is the one I have been using, which basically covers any kind of overvoltage situation other than utilities setting the voltage too high. And this is the term most CONSUMERS would use over this broad range of definition, and the scope of protection they expect.
|> | MOVs are rapidly destroyed by long duration events. Martzloff has |> | written "in fact, the major cause of [surge suppressor] failures is a |> | temporary overvoltage, rather than an unusually large surge." |> |> Then they need to design for that. | . | As has been covered in this newsgroup before, it is not practical to | protect from temporary overvoltage with MOVs. Only practical protection | I know of is to disconnect from the source. Depending on how high the | overvoltage that may not work well.
It's also silliness to expect any ONE SINGLE COMPONENT to provide the entire scope of protection. For example, I don't expect an MOV to protect against extremely fast rise times. Low pass filters are for that. Protection needs to come in the form of a system that provides all different kinds of protection within reason (the incident in Harford county _may_ be a case that is not practical to protect against at a level most consumers want to deal with). The system needs to work together so that what is done to provide one form of protection does not end up degrading other forms of protection. For example, we must have the grounding electrodes correctly wired at the point of entrance and not connected at other points in the building (with certain exceptions that won't generally exist for residences).
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snipped-for-privacy@ipal.net wrote:

. I did. .

. If you want to use defined terms in nonstandard ways maybe you should post on a non-engineering newsgroup. It is not possible to communicate when there is no common language (surge) or science (phil's phantasy physics). . > |> | MOVs are rapidly destroyed by long duration events. Martzloff has

. MOVs are faster than surges.
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| snipped-for-privacy@ipal.net wrote:
|> |> |> |> |> |> |> I notice from videos of the 33kV surges that happened to homes in Harford |> |> |> |> county MD, severe damage levels was propogated into at least the inside |> |> |> |> breaker panels. If the arcing at the meter and the service cable does not |> |> |> |> completely quench the surge, and it gets to the panel and destroys that, |> |> |> |> then why not also go beyond and take out appliances? The question is just |> |> |> |> how much voltage reached each point. Arcs have a voltage drop, but they |> |> |> |> do also have impedance (inductance). So they cannot completely clear a |> |> |> |> differential surge. Clearly the arc at the meter did not clear the surge |> |> |> |> since there was more surge damage at the panel. |> |> |> | . |> |> |> | It was not a surge. |> |> |> |> |> |> So do you classify anything happening to utility equipment as NOT a surge? |> |> | |> |> | A surge is, by definition, a very short event - certainly well under a |> |> | cycle. The next most damaging surges, after lightning, are generally |> |> | from utility switching. Crossed power lines like Hanford are far too |> |> | long duration and are "temporary overvoltage" or maybe "swells" (up to a |> |> | few seconds). |> |> |> |> My definition of a surge is bigger than your definition of a surge! |> | . |> | My definition of surge is industry standard including the IEEE. It works |> | better if you use the same definitions other people do. |> |> My interest is in protecting against that which I have termed "surge" under |> my definition. If you have a better term to use that covers my definition, |> please suggest it. | . | I did. | . |> Until then, the only term I have is the one I have been |> using, which basically covers any kind of overvoltage situation other than |> utilities setting the voltage too high. And this is the term most CONSUMERS |> would use over this broad range of definition, and the scope of protection |> they expect. | . | If you want to use defined terms in nonstandard ways maybe you should | post on a non-engineering newsgroup. It is not possible to communicate | when there is no common language (surge) or science (phil's phantasy | physics).
If you can't understand what is being communicated, then don't respond. I've communicated by definition of surges before. Any time you need to be reminded, just ask.
| > |> | MOVs are rapidly destroyed by long duration events. Martzloff has |> |> | written "in fact, the major cause of [surge suppressor] failures is a |> |> | temporary overvoltage, rather than an unusually large surge." |> |> |> |> Then they need to design for that. |> | . |> | As has been covered in this newsgroup before, it is not practical to |> | protect from temporary overvoltage with MOVs. Only practical protection |> | I know of is to disconnect from the source. Depending on how high the |> | overvoltage that may not work well. |> |> It's also silliness to expect any ONE SINGLE COMPONENT to provide the entire |> scope of protection. For example, I don't expect an MOV to protect against |> extremely fast rise times. | . | MOVs are faster than surges.
So what. That doesn't make them perfect. There are two issues:
The leading edge of a fast rising surge wavefront will NOT propogate only to the MOVs in the hopes that the MOV will provide a low impedance path somewhere. The true fact is that the wavefront will propogate in all directions in some proportion dictated by the reactive aspects of the wiring involved.
The common mode surge will present no voltage differential across the MOV at the point of use.
A very fast rising common mode surge, which would typically result from a potential induced directly into branch circuit wiring, would bypass MOVs and go directly to appliances. Differences in distance (timing) and reactance in the paths to different appliances in the point of use zone protected by a given protector can result in brief high voltage differences between these interconnected appliances. Additionally, branch wiring within the appliance can result in differences within.
Of course bud will just pretend these not-so-common types of surges do not ever happen.
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Dear Phil
While I have no intension of being drawn into discussions relating to this topic, I would like to bring to your attention an excellent publication by the IEEE that covers most aspects of surge suppression technology as it relates the protection of your home. Please see "How to Protect Your House and its Contents from Lighting", this publication covers both the requirements under US standards and why some systems work better than others.
BillB
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snipped-for-privacy@nospam.tesco.net wrote:

I agree it is an excellent source. Available at: <http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf
Phil said there was a "lack of interest" on the part of the authors "to explore the field of fast rise time pulses and edge transitions".
Of IEEE standards for characterizing surges Phil said "they've missed a lot of reality."
Of an experiment by Francois Martzloff, an expert in the field, that directly contradicts Phil, Phil says "then he flubbed the experiment."
Of Martzloffs comments, quoted earlier, for raising clamp voltages Phil said Martzloff had a "hidden agenda".
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bud-- wrote:

<http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf
Phil lives in a tiny fantasy world, where he is the only one who knows anything.
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On Mon, 29 Sep 2008 12:34:04 -0400 Michael A. Terrell
| | bud-- wrote: |>
|> > Dear Phil |> > |> > While I have no intension of being drawn into discussions relating to this |> > topic, I would like to bring to your attention an excellent publication by |> > the IEEE that covers most aspects of surge suppression technology as it |> > relates the protection of your home. Please see "How to Protect Your House |> > and its Contents from Lighting", this publication covers both the |> > requirements under US standards and why some systems work better than |> > others. |> |> I agree it is an excellent source. Available at: |> <http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf |> |> Phil said there was a "lack of interest" on the part of the authors "to |> explore the field of fast rise time pulses and edge transitions". |> |> Of IEEE standards for characterizing surges Phil said "they've missed a |> lot of reality." |> |> Of an experiment by Francois Martzloff, an expert in the field, that |> directly contradicts Phil, Phil says "then he flubbed the experiment." |> |> Of Martzloffs comments, quoted earlier, for raising clamp voltages Phil |> said Martzloff had a "hidden agenda". | | | | Phil lives in a tiny fantasy world, where he is the only one who | knows anything.
Michael A. Terrell is one of those people that contributes absolutely NOTHING when he faces someone he doesn't like, or who says things he doesn't like. Mr. Terrell does have knowledge of science, technology and engineering. But he is a bitter person, possibly due to the health conditions he faces, or maybe due to some bad experiences in life. He has become antisocial and prefers to make personal attacks on people instead of conducting discussion on a point by point basis. He could discuss, and in many cases he does. But when he has the opportunity to make personal attacks, it's like he switches personality.
Google Groups can show you his past posts. Judge for yourself.
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| snipped-for-privacy@nospam.tesco.net wrote: |> Dear Phil |> |> While I have no intension of being drawn into discussions relating to this |> topic, I would like to bring to your attention an excellent publication by |> the IEEE that covers most aspects of surge suppression technology as it |> relates the protection of your home. Please see "How to Protect Your House |> and its Contents from Lighting", this publication covers both the |> requirements under US standards and why some systems work better than |> others. | | I agree it is an excellent source. Available at: | <http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf | | Phil said there was a "lack of interest" on the part of the authors "to | explore the field of fast rise time pulses and edge transitions".
They don't seem to have that interest. It could be because these kinds of surges happen less often. It takes a close lightning strike for it to happen.
| Of IEEE standards for characterizing surges Phil said "they've missed a | lot of reality."
They are at least not covering all of it. It's not practical to cover it all in one document.
| Of an experiment by Francois Martzloff, an expert in the field, that | directly contradicts Phil, Phil says "then he flubbed the experiment."
This comment was pointed at Bud, who misunderstand the science behind any of this. I don't believe Martzloff flubbed anything. Instead, he just did not focus on it. Bud misunderstands this. Bud assumes ONE document is complete coverage of all science.
| Of Martzloffs comments, quoted earlier, for raising clamp voltages Phil | said Martzloff had a "hidden agenda".
Again, this is for Bud's benefit so maybe it would spur him to think about what he reads instead of just spouting off misapplied science. I was hoping he would be able to learn. This was a while back. He's show no learning since then, which suggests he might be full.
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On Sun, 28 Sep 2008 17:32:48 GMT snipped-for-privacy@nospam.tesco.net wrote: | Dear Phil | | While I have no intension of being drawn into discussions relating to this | topic, I would like to bring to your attention an excellent publication by | the IEEE that covers most aspects of surge suppression technology as it | relates the protection of your home. Please see "How to Protect Your House | and its Contents from Lighting", this publication covers both the | requirements under US standards and why some systems work better than | others.
These documents have been long discussed here. But there are people here who don't read it carefully. Also, they cover a lot of incorrect situations where things like existant wiring are wrong. Those cases pose great difficulty in finding good solutions. I have no interest in them.
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snipped-for-privacy@ipal.net wrote:

Anyone interested can google for "phil's phantasy physics".
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| snipped-for-privacy@ipal.net wrote: |> |> The leading edge of a fast rising surge wavefront will NOT propogate only to |> the MOVs in the hopes that the MOV will provide a low impedance path somewhere. |> The true fact is that the wavefront will propogate in all directions in some |> proportion dictated by the reactive aspects of the wiring involved. | | Anyone interested can google for "phil's phantasy physics".
And then they can compare that to real physics, and if the understand what they read, they can see the fantasy is in Bud's head.
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|> In a previous thread a reference was made to an expert recommendation |> that surge suppressors have their clamping voltage doubled from 330V |> to 660V for 120VAC suppressors. |> |> Originally, I thought that was a bad idea. But now I think maybe |> that will be useful. How I came to that conclusion was finding that |> suppressors were not readily available for 240VAC power systems. |> With such a change in the clamping voltage, I could use these more |> common suppressors as part of the changeover from 120V to 240V for my |> computers. |> |>> WARNING: Due to extreme spam, googlegroups.com is blocked. Due to |>> ignorance | by the abuse department, bellsouth.net is |>> blocked. If you post to | Usenet from these places, find |>> another Usenet provider ASAP. | |>> Phil Howard KA9WGN (email for humans: first name in lower case at |>> ipal.net) | | | The clamping voltage statement doesn't sound right. I'd go back and | reread the information and pay particular attention to the knee voltage | and the current rank just prior to it. I'm not saying it's a bad idea; | just that it might have a lot of leakage on 240 that surpasses the | component's temp ratings.
If you designed and constructed a real 240V protector, would you not make it have twice the clamping level?
| You don't give enough info on how you plan to use these, but I do know | that the UK style 230Vac 50Hz does have accomodating surge suppressors. | Their grid is configured differently than here in the US where I am of | course.
I would use it here in the US on the US style 240V system which is 120V to ground on each of two hot wires in opposing polarity (180 degrees in the case of genuine 240V single phase).
I have considered using a German power strip, and just make my computer wiring all based on the Schuko. The Schuko is unpolarized and symmetric, even though the electrical system it is based on is 230V L-N. But they require devices to be safe when plugged in either way. So these devices should be able to handle 230V relative to ground on either conductor, as we as between conductors.
The change of clamping voltage from 330V to 660V would means I might be able to find devices with protective components that could handle 240V L-L *AND* be able to support replacing NEMA 5-15R outlets with NEMA 6-15R outlets. I would prefer to use the NEMA 6-15's over the Schuko.
Alternatively to the Schuko, which is more common, I might use the Italian plug/outlet design.
Most of my "wall wart" power supplies are rated for 100-240 volts. But they all have NEMA 1-15P on them. So I'll still need to either put 240V on a NEMA 5-15R or just run these on 120V.
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snipped-for-privacy@ipal.net writes:

I have seen (older) power strips that use 3 or so ordinary duplex 5-15R recepticles in a row. If you want to make your own, try to find these and replace the outlets with 6-15R's.
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On Thu, 18 Sep 2008 15:48:40 +0000 (UTC) Michael Moroney
| snipped-for-privacy@ipal.net writes: | |>I would use it here in the US on the US style 240V system which is 120V to |>ground on each of two hot wires in opposing polarity (180 degrees in the |>case of genuine 240V single phase). | |>I have considered using a German power strip, and just make my computer |>wiring all based on the Schuko. The Schuko is unpolarized and symmetric, |>even though the electrical system it is based on is 230V L-N. But they |>require devices to be safe when plugged in either way. So these devices |>should be able to handle 230V relative to ground on either conductor, as |>we as between conductors. | | I have seen (older) power strips that use 3 or so ordinary duplex 5-15R | recepticles in a row. If you want to make your own, try to find these and | replace the outlets with 6-15R's.
That was the idea ... except in for some wall warts I'll still need 5-15R.
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On Sep 15, 11:44 pm, snipped-for-privacy@ipal.net wrote:

Those voltages are ball park numbers. Actual voltage curve is not a step function or 'knee voltage' as so many want to believe. A protector rated at 330 volts will conduct current even at 130 V RMS. How much current determines how quickly an MOV degrades. Yes, degrades because MOVs inside protectors must fail only by degrading; a change in its threshold voltage. A 10% change means the MOV has failed.
Typically, MOVs for 330 volts will also conduct at 180 volts AND will increase voltage to greater than 800 volts as a surge current increases. So what is its voltage? That would be the MOV inside a 330 volt protector. 330 or 660 volt numbers are ballpark - arbitrary. See MOV datasheets for the V-I charts.
An MOV used in 120 volt operation must conduct less than acceptable current at 185 volts. Idea is to select an MOV that conducts under a minimum acceptable current constantly. How do we measure MOV threshold voltage? One standard is to push a constant 1 milliamp through the MOV and read its voltage. If that voltage changes by 10%, then the MOV has degraded - failed. IOW that 1 milliamp voltage should be sufficiently above 185 for 120 VAC operation and above 370 for 240 VAC operation. These would also be 330 volt and 660 volt let- through voltages.
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In Europe the standard for surge suppression devices is EN 61643-11. Voltage limiting devices a listed as Class 3 devices. This is a harmonised standard listed in the Official Journal of the EU. This mean it is a means of demonstrating compliance with the European Low voltage Directive. We have been testing to this standard for the last 3 years and have not yet had a first time pass. It has recently been revised and this makes compliance even more difficult to achieve.
BillB
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snipped-for-privacy@nospam.tesco.net wrote:

What are the problems?
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