On Sun, 20 Jul 2008 10:51:22 -0500 bud-- wrote: | email@example.com wrote: |> On Fri, 18 Jul 2008 11:22:00 -0500 bud-- wrote: |> | w_tom wrote: |> |> So where does that plug-in protector dissipate surge energy |> |> harmlessly in earth? It does not. |> | . |> | If not hindered by religious blinders w_ could read the answer in the |> | IEEE guide (starting pdf page 40). The IEEE guide explains plug-in |> | suppressors work by CLAMPING the voltage on all wires (signal and power) |> | to the common ground at the suppressor. Plug-in suppressors do not work |> | primarily by earthing (or stopping or absorbing). The guide explains |> | earthing occurs elsewhere. |> |> Clamping does not make surge energy disappear. | . | Clamping makes the voltage between wires going to the protected | equipment safe for the protected equipment.
See what I said later in that post you are replying to. Sure, it does equalize the difference for the most part. Other aspects of the surge are not affected, or are affected in only minimal ways. For example the surge front waveform is reduced because some of the energy can go across the clamp and take another path away from the appliance. But this is only reducing the energy to some fraction that can still be enough to cause damage.
|> It is nothing more than a |> form of diversion. It creates a path, when the voltage difference is high |> enough, to an alternate wire, such as ground. Now the surge energy has |> 1 or 2 more paths to go, for a total of 2 or 3 (depending on whether the |> wire the voltage is clamped is and end point, or the middle of a run of |> wire). Just because the clamping has created the path does not mean all |> of the energy will go that way. | . | Repeating: | "Plug-in suppressors do not work primarily by earthing."
You have sounded like a broken record for a long time. And why do you even need to say this?
| And repeating: | "The guide explains earthing occurs elsewhere."
You still sound like a broken record.
| Perhaps if you read and understood the example in the IEEE guide, | starting pdf page 40....
Maybe you can just point at a statement I have made that contradicts it.
Your _big_ problem is your failure to be able to discuss these points you keep referring to. That suggests to me you don't really understand what IEEE says enough to be able to defend it on your own. All you do is point at it ... even in cases where it is irrelevant (e.g. cases where someone did NOT contradict it, or was discussing something unrelated).
Hint: pointing does not make other people wrong
What I suggest you do is read what you want to base your arguments on very thoroughly and build your own knowledge base so you can defend it completely independently. Then you need to actually focus on something someone says that you think is wrong, and explain (not point to some document) why you believe it is wrong, and provide the correct statement you think is right (and do this without pointing away at some document).
|> The proportions depend on the characteristic |> impedance, as that is the only impedance that has an immediate effect with |> reflection time frame short enough to not need to be considered. | . | Francois Martzloff was the NIST guru on surges. He did research and has | many published papers on surges and surge suppression. | On transmission line behavior Martzloff writes: | "From this first test, we can draw the conclusion (predictable, but too | often not recognized in qualitative discussions of reflections in wiring | systems) that it is not appropriate to apply classical transmission line | concepts to wiring systems if the front of the wave is not shorter than | the travel time of the impulse. For a 1.2/50 us impulse, this means that | the line must be at least 200 m long before one can think in terms of | classical transmission line behavior."
You've quoted this before. In all cases I can remember, you quoted it inapplicably. The evidence of your error exists right there in the words you quoted. The part that says "if ..." is a conditional. It means that the statement being made only applies under certain circumstances. Yet you (who don't seem to understand this) quote this even where it does not apply (e.g. in cases where the if-clause is not met).
| I have posted this at least twice previously in response to your | comments on transmission line behavior. Your response was that Martzloff | "flubbed the experiment". You have never provided a supporting source | for you belief.
The "supporting source" is the very statement you quote. Again, it is a conditional statement that depends on a specific kind of impulse/waverform timing.
His "flubbed" experiment was not one to characterize all surges. I say it was "flubbed" because it did not meet the needs YOU are trying to apply it to (which seems to be the assumption that all surges are alike).
| Provide a source that agrees with you that transmission line effects | have to be considered for surges in other than large buildings.
I don't intend to do that. I don't need to. It is not my objective or obligation to make you believe something. It should be up to you to find out the truth, and figure out and understand the circumstances where your statements apply and do not apply.
|> A combination of protection mechanisms, as long as they are installed |> properly, can provide the best level of protection for appliances. Just |> how much protection to use is a balance among the cost of protection, |> the cost of loss, and the risk factors. There is no universal answer. |> The optimal choice is made by people that understand what all is going |> on, not by people that parrot documentation suited only for specific |> situations, or intended to describe specific protection devices. | . | The IEEE guide "was written to make the information developed by the | [IEEE Surge Protection Devices Committee] more accessible to | electricians, architects, technicians, and electrical engineers who were | not protection specialists." | The guide includes for protection: | 1 earthing of the systems | 2 short connections between signal entry protectors and power system | earthing | 3 service panel suppressors | 4 plug-in suppressors for 'sensitive' electronics, particularly with | both signal and power connection | | The guide is for general surge protection using the most common | techniques. It is not aimed at "specific situations". You show little | indication you have read or understood the guide. I realize you didn?t | write it, so it probably isn't worth reading.
This is a guide for people who are only going to be doing minimal levels of protection. A minimal level happens to be adequate for most people. This guide does not cover the extensive protection needed that balances between special requirements and the rare and very destructive extreme surges.
| My comments in response to w_ are disproportionately about plug-in | suppressors because of the nonsense w_ posts about them.
Maybe you should just disregard him entirely.
|> |> No plug-in protector even claims to |> |> protect from the typically destructive surge. |> | . |> | Humor for the day. |> | |> | For real science read the IEEE and NIST guides. Both say plug-in |> | suppressors are effective. |> |> ... for certain kinds of surges. They are NOT universal protection for all |> kinds of surges. |> |> The "destructive" surges he speaks of may be the ones that vaporize plug-in |> suppressors. A direct strike can do that. | . | If by direct strike you mean a direct lightning strike to a building, | protection requires lightning rods. There is no point in talking about | protection without rods.
Amazing. You managed to make a statement of some significant "fact" without pointing to some document that may not be applicable.
| For surges coming in on utility wires, the impedance of the branch | circuit greatly limits the current, and thus energy, that can reach a | plug-in suppressor. Investigations by Martzloff with surges up to | 10,000A at a power service (the maximum reasonable surge) and branch | circuits 30 ft and longer with a MOV at the end, showed surprisingly | small energy absorption at the MOV. The maximum energy dissipated in the | MOV was 35 Joules. In 13 of 15 cases it was 1 Joule or less. One reason | is the branch circuit impedance. The other is that at about 6,000V (US) | there is arc?over from service panel busbars to | enclosure/ground/neutral/earth. After the arc is established the arc | voltage is hundreds of volts. That dumps most of the surge energy to | earth. Receptacles (US) will also arc-over at about 6,000V.
First of all, an MOV is not going to absorb much energy. It is a device that creates a low impedance path between two conductors. The energy it absorbs is the current, times the voltage DROP, integrated over time.
What is of more concern is where the rest of the energy went. It goes out in all directions in response to impedance characteristics.
| Neither service panel or plug-in suppressors protect by absorbing | energy. The absorb energy in the process of protecting.
Maybe you can explain what your statement means. Or maybe you can't.
|> | There are 98,615,938 other web sites, including 13,843,032 by lunatics, |> | and w_ can't find another lunatic that says plug-in suppressors are NOT |> | effective. All you have is w_'s opinions based on his religious belief |> | in earthing. |> |> Why is it that you always seem to want a binary answer about whether a |> surge protection device is or is not effective? The true and correct |> answer will be "it depends". | . | w_ says never. What I have read from many Martzloff papers and other | sources is that plug-in suppressors with high ratings connected properly | are very unlikely to fail. That is why some plug-in suppressors can have | connected equipment warrantees.
The existance of a warrantee does not ensure protection. Surges do not give a damn about the warrantee. If they did, they'd probably make more of an effort to destroy everything just to spite the owner of the devices.
|> | Never answered - embarrassing questions: |> | - Why do the only 2 examples of protection in the IEEE guide use plug-in |> | suppressors? |> |> Because the IEEE guide you looked at is a guide about how to use plug-in |> suppressors to their greatest effectiveness. | . | Your comment is beyond stupid. Perhaps if you read the guide....
Perhaps if you applied the guide correctly.
I read it a long time ago. It didn't cover all aspects of protection. Since it was intended for specific readers, it doesn't even need to cover all aspects.
|> | - Why does the NIST guide says plug-in suppressors are "the easiest |> | solution"? |> |> Because the average person is not skilled to do the correct installation of |> other kinds of protection. | . | The NIST guide covers the same basic protection as the IEEE guide. It | also has a "contractor" section with more technical information. Perhaps | if you read the guide....
Read it, too, a long time ago. I have no reason to go back. You have not stated any such reason.
|> | ? Why don?t airplanes drag an earthing chain? |> |> That would make it too easy for terrorists to grab hold of and yank the plane |> down. |> |> Silly question, silly answer. | . | It is a serious question. w_ says you can?t protect without the | protector directly earthing the surge. Then it is not possible to | protect airplanes.
It seems you have a broad lack of understanding, despite reading all these various guides.