Surge / Ground / Lightning
in [Home Built PC]
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From: phil-news-nospam on 4 May 2008 15:08 In alt.engineering.electrical Timothy Daniels <SpamBucket(a)nospamplease.biz> wrote: | Would you please sum up what you believe to be prudent | protection (for electronic equipment) from nearby lightning strikes? | I'm thinking of both in single-family homes and in condo/apartment | buildings. What would you do to protect from in-house (or in-building) | surges, such as elevator motors suddenly shorting out, or welding | equipment in use? How much money are you willing to spend? -- |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: phil-news-nospam on 4 May 2008 15:19 In alt.engineering.electrical VWWall <vwall(a)large.invalid> wrote: | Actually, a real current will flow until the line's capacitance is | charged to the source voltage. When the source is removed, the energy | involved will remain until it is leaked off through the inter-wire | resistance. If the source is AC, no net energy will "flow", except that | lost in the inter-wire resistance. If the line length is long enough at | the frequency involved, reflections from the end of an incorrectly | terminated transmission line will return to dissipate energy in the | source resistance. That reflection even happens with DC. When the switch closes, you have a rising wavefront leading the chargeup of the line. Unless the far end has a perfectly matched load, that wavefront will reflect back. This is in fact how a lot of very early radio transmissions were tuned, with the "switch" being a noisy spark gap, and the "line" being a long wire antenna cut to a specific length. You don't even need to have 2 conductors. | -- | Virg Wall, P.E. | K6EVE They seem to not believe me because I am a "mere amateur". You might suffer the same fate from some of them (I won't name names; it's not hard to figure out who they are). -- |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: phil-news-nospam on 4 May 2008 15:20 In alt.engineering.electrical Timothy Daniels <SpamBucket(a)nospamplease.biz> wrote: | "Tony Hwang" wrote: |> You seem to be confused between current flow(energy) and voltage(poential) |> Nothing flows in an open circuit. If not we |> have to rewrite Ohm's law. Show your credential to make a |> stamement like that. | | | You're forgetting RF frequencies - which can flow (back | and forth) quite readily in an open circuit such as a transmitter | tower, whip antenna, or transmission line, or building power | wiring, steel frame, etc. I think they intentionally ignored it. Well, maybe Mr. Terrell actually forgot. -- |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: phil-news-nospam on 4 May 2008 15:24 In alt.engineering.electrical Tantalust <Tantalust(a)paradise.net> wrote: | <phil-news-nospam(a)ipal.net> wrote in message | news:fvgri141nb(a)news1.newsguy.com... |> In alt.tv.tech.hdtv Tantalust <Tantalust(a)paradise.net> wrote: |> | <phil-news-nospam(a)ipal.net> wrote in message |> | news:fvfqmk125dl(a)news4.newsguy.com... |> |> In alt.tv.tech.hdtv Tantalust <tantalust(a)paradise.net> wrote: |> |> | |> |> | <trader4(a)optonline.net> wrote |> |> | |> |> |>Maybe he taken a hiatus after the right propper whopping he got here |> |> |>last week. I thought it was hillarious after he derided the makers |> |> |>of plug-in surge protectors and then gave us his list of "real |> |> |>companies", like Intermatic, GE, Leviton, etc., that were experts at |> |> |>it. Only problem was, all of the companies on his list sell |> plug-in |> |> |>ones too. |> |> | |> |> | Huh, so according to all of w_'s sermons, Bud must be working |> overtime |> |> as a |> |> | salesman for all of those companies too? Busy guy! |> |> |> |> Both do not appear to be wrong to me. They appear more to be arguing |> |> about |> |> entirely different issues. But I can't be entirely sure because their |> |> rants |> |> are hard to read and I skip a lot of it, including any post where the |> |> first |> |> screenful is all quoted text. And my googlegroups filter is killing |> off |> |> the |> |> posts from w_tom that don't have any threading where I have posted. |> | |> | Is googlegroups filtering possible using Outlook Express? |> |> Not that I know of. But my reader is configured to filter out |> Googlegroups |> due to Google's lack of action to deal with the massive spam floods they |> let |> reach Usenet. Not only is there many times as much spam from Googlegroups |> as legitimate posts in the groups I read, but in many, the level of normal |> posts has fallen, suggesting that this issue is causing some to abandon |> Usenet |> because of this. | | Thanks for the info. I should clarify that where I said "many times as much spam from Googlegroups as legitimate posts in the groups I read" I was referring to legitimate posts ALSO FROM Googlegroups (the ones I would lose by blocking). In some cases the spam truly was in excess of ALL legitimate posts. As it turns out, my newsreader will still show the killed posts with a "K" in the threading displays. So if someone followed them, or they followed one of mine, I can at least pick it. But the normal tabbing through new posts still skips them. -- |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: VWWall on 4 May 2008 15:34
phil-news-nospam(a)ipal.net wrote: > In alt.engineering.electrical VWWall <vwall(a)large.invalid> wrote: > > | Actually, a real current will flow until the line's capacitance is > | charged to the source voltage. When the source is removed, the energy > | involved will remain until it is leaked off through the inter-wire > | resistance. If the source is AC, no net energy will "flow", except that > | lost in the inter-wire resistance. If the line length is long enough at > | the frequency involved, reflections from the end of an incorrectly > | terminated transmission line will return to dissipate energy in the > | source resistance. > > That reflection even happens with DC. When the switch closes, you have a > rising wavefront leading the chargeup of the line. Unless the far end has > a perfectly matched load, that wavefront will reflect back. This is in > fact how a lot of very early radio transmissions were tuned, with the > "switch" being a noisy spark gap, and the "line" being a long wire antenna > cut to a specific length. You don't even need to have 2 conductors. That's because a switch closure is not really DC. Resolve a step function into a Fourier series, and it has an infinite number of AC components. In the case of a single wire, you do need to consider EM theory. -- Virg Wall, P.E. K6EVE P1-11-49835 T2-11-49835 |