Surge / Ground / Lightning
in [Home Built PC]
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From: Timothy Daniels on 5 May 2008 14:15 "Michael A. Terrell" advised: > Use a combination of protection at the building's main disconnect, > and individual protection at each critical device. Does that mean a combination of w_tom's "whole house protection" and individual "surge protectors" at those "critical devices"? That's what I've always felt would be prudent - not a single method of protection, but a combination. *TimDaniels*
From: Mike Tomlinson on 5 May 2008 14:19 In article <2seu14tkjc068ph626ahu4akieb1pqa38f(a)4ax.com>, spamfree(a)spam.heaven writes >I'm curous to know how surge suppression can work without a ground >(earth) of any sort. Surge suppressors usually have three MOVs: one between phase and neutral, and one each from phase and neutral to earth. On properly grounded outlets, such a suppressor can deal with an incoming surge on phase or neutral in an effective manner by conducting and diverting current to the other leg AND to ground, but their effectiveness when used on ungrounded outlets is reduced, since the path to ground doesn't exist. w_twat chooses to conveniently ignore this fact and continues to peddle his unique brand of lies, misrepresentation and FUD in his own inimitable style, which another poster has described as "hostile". It's telling that w_ was unable to understand that people perceive his posting style as hectoring or hostile, which should give you some idea of his mental state :) Best place for w_'s posts is in the killfile. -- (\__/) Bunny says NO to Windows Vista! (='.'=) http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.html (")_(") http://www.cypherpunks.to/~peter/vista.pdf
From: phil-news-nospam on 5 May 2008 14:20 In alt.engineering.electrical trader4(a)optonline.net wrote: | On May 5, 1:44?am, phil-news-nos...(a)ipal.net wrote: |> In alt.tv.tech.hdtv bud-- <remove.budn...(a)isp.com> wrote:| phil-news-nos...(a)ipal.net wrote: |> |> |> In alt.engineering.electrical Leonard Caillouet <nos...(a)noway.com> wrote:|> | <phil-news-nos...(a)ipal.net> wrote in message |> |> |> |news:fvjhvk016vr(a)news5.newsguy.com... |> |> |> In alt.tv.tech.hdtv Franc Zabkar <fzab...(a)iinternode.on.net> wrote: |> |> | |> |> |> |> |> |> The MOVs will act like conductors when they are clamping. ?The surge will |> |> |> take both paths ... the path through the MOVs, and the path going past the |> |> |> MOVs. ?In general, about 50% will go each way. ?That can vary at higher |> |> |> frequencies. |> |> | |> |> | Why would you assume that 50% will go each way when you don't know the |> |> | impedance of each direction? ?When conducting, or at failure, the MOV has a |> |> | very low impedance. |> |> |> |> There is a distinction between "go each way" and "what comes back" due to |> |> the impedance. ?It will be about 50% that goes each way _because_ the power |> |> itself does not (yet) know the impedance (at a distance), until it gets |> |> there. |> | |> | Another installment of Phil's Phantasy Physics using transmission line |> | theory. |> |> Not understanding it is your loss. | | | I have to agree that this is Phantasy Physics. We're supposed to | believe that a surge reaching a MOV is going to split 50-50, with half | of it going to the MOV path and half moving on down the line, | reagrdless of the impedance of the two paths? That would render all | surge protection about 50% effective. You did not read very carefully. The reference to 50-50 split is about the contribution of the MOVs themselves. That is an essential understanding of the components so the whole system can be figured out. The impedance down the paths is another separate component, which also has to be figured in when determining the whole picture. You have confused a component with the entire system. You need to read more carefully. Or you need to understand the distinction of individual components as they apply to the whole system The whole wiring system is extrememly complex. It cannot be understood properly without first understanding the components. And that includes understanding that MOVs, when they conduct, do look to the propogating energy as two paths to go down, and it will (initially) go both ways in about an equal amount. -- |WARNING: Due to extreme spam, I no longer see any articles originating from | | Google Groups. If you want your postings to be seen by more readers | | you will need to find a different place to post on Usenet. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
From: bud-- on 5 May 2008 14:30 phil-news-nospam(a)ipal.net wrote: > In alt.tv.tech.hdtv bud-- <remove.budnews(a)isp.com> wrote: > | phil-news-nospam(a)ipal.net wrote: > |> In alt.tv.tech.hdtv bud-- <remove.budnews(a)isp.com> wrote: > |> | phil-news-nospam(a)ipal.net wrote: > |> |> In alt.tv.tech.hdtv bud-- <remove.budnews(a)isp.com> wrote: > > |> |> For example, consider the high frequency issue. High frequency energy is > |> |> less common than low frequency energy. Partly this is because the chance > |> |> of a closer lightning strike is less than a more distant one. A strike > |> |> within 100 meters is only 1/8 as like as a strike outside of 100 meters > |> |> but within 300 meters. Some people then feel that they can dismiss high > |> |> frequency energy issues entirely. > |> | > |> | Francois Martzloff was the surge guru at the NIST and has many published > |> | papers on surges and suppression. In one of them he wrote: > |> | "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." > |> | Residential branch circuits aren't 200m. > |> | > |> | Your response: "Then he flubbed the experiment." In another case you > |> | have said Martzloff had a hidden agenda. > |> > |> I addressed this one elsewhere. You seem to have misunderstood him. > |> He did not say that wiring systems do not exhibit transmission line > |> characteristics. > | > | If you had actually read the quote: > | "*it is not appropriate to apply classical transmission line concepts to > | wiring systems*" > | and "*this means that the line must be at least 200 m long before one > | can think in terms of classical transmission line behavior*." > | > | Repeating: "Residential branch circuits aren't 200m." > > You are now taking what Martzloff said out of context. He _qualified_ > what he said in terms of a statement conditional. Following the part > you just now quoted is "... if the front of the wave is not shorter than > the travel time of the impulse." Then he added "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." > > Hint: what "if" means is that if the conditional is not met, then the > statement does not apply. > > Martzloff's statement is actually correct. Your quoting of it is wrong. > I suspect your understanding of it is weak or maybe even wrong. I believe > you are misapplying it. Then when _my_ statement contradicts _your_ > incorrect understanding, you somehow think *I* am contradicting him. > > His statement is qualified for a specific slow impulse rise time that > corresponds to a lower frequency. He has NOT said (in what you quoted > in earlier posts here) that no surge can ever have a faster rise time. > He has NOT said that you cannot think in terms of transmission line > behaviour for faster rise times, even on shorter wiring/circuits. Previously you said Martzloff "flubbed the experiment". Now you agree with Martzloff that branch circuit must be 200m for transmission line behavior with 1.2 microsecond rise time. You say that doesn't apply because surges are faster. Martzloff uses 1.2 us because that is a standard rise time for surges produced by lightning as defined in IEEE standards. w_' professional engineer source says 8 micoseconds with most of the spectrum under 100kHz. You still have *no sources that support your belief* that risetimes are far faster. > > |> | You claim lightning induced surges have rise times about a thousand > |> | times faster than accepted IEEE standards - which are experimentally > |> | derived. > |> > |> So you are narrowing this statement to only induced surges? > | > | I intended "induced" meaning produced by including the most damaging - > | strikes to utility lines. > > The most damaging strikes tend to be ones that are NOT induced. Do you > understand what induction and inductive coupling is? > > Lightning does not have to directly strike the wire for there to be a > surge on it. That is induction when there is no direct strike. If the > strike _is_ directly on the wires, that's different (and has the exposure > of substantially more voltage/current). Again you did not read what I wrote (what a surprise): "I intended 'induced' meaning produced by including the most damaging - strikes to utility lines." -- bud--
From: bud-- on 5 May 2008 14:35
w_tom wrote: > > Both of Bud's citations - guides for laymen The IEEE guide is aimed at "electricians, architects, technicians, and electrical engineers who were not protection specialists." > > Bud quotes from Martzloff > selectively. Meanwhile this conclusion is so fundamental that > Martzloff makes it the first point in his IEEE paper: Quotes selectively? How pathetic. w_ forgets to mention that Martzloff said in the same document: "Mitigation of the threat can take many forms. One solution. illustrated in this paper, is the insertion of a properly designed surge reference equalizer [multiport plug-in surge suppressor]." In 2001 Martzloff wrote the NIST guide which also says plug-in suppressors are effective. > Also are those 'scary pictures of plug-in protectors And lacking valid technical arguments w_ repeats the lie again. Still missing - a link to any source that says UL listed plug-in suppressors made after 1998 are a problem. Still missing - a source that agrees with w_ that plug-in suppressors are NOT effective. Still missing - answers to simple questions: - Why do the only 2 examples of surge suppression in the IEEE guide use plug-in suppressors? - Why does the NIST guide says plug-in suppressors are "the easiest solution"? - Why do all but one of w's "responsible manufacturers" make plug-in suppressors? - Why does SquareD say in addition to their "whole house" suppressors "electronic equipment may need additional protection" from plug-in suppressors. - Why aren't airplanes crashing daily when they get hit by lightning (or do they drag an earthing chain)? For real science read the IEEE and NIST guides. Both say plug-in suppressors are effective. -- bud-- |