Surge Protectors
in [Repair]
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From: Sjouke Burry on 19 Jun 2010 18:47 Jim Yanik wrote: > "William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote in > news:hvigjf$hg7$1(a)news.eternal-september.org: > >>> It is bud's job to constantly promote lies and myths. He is paid >>> to promote plug-in protectors. Lying is what promoters may do. >>> Where are those numeric specs? bud will never provide any. >>> He cannot claim protection that does not exist. >>> Where does that energy dissipate? bud cannot say. Otherwise >>> he must admit that plug-in protectors are profit centers � not >>> protection. >> Uh... In the MOV? >> >> I thought the MOV conducted above its breakdown voltage (generally >> around 300V), and the energy in the section of the AC waveform above >> that voltage heated up the MOV. >> >> Am I missing something? > > Ohm's Law. > If the MOV conducts at a low resistance,the power it dissipates will be > minimal. > Thus,the surge energy gets dissipated in whatever ground it's shunted to. > > Bullshit. The Mov dissipates (Umov)*I*T, or Total Energy=MOVvolts * Current * Seconds. Or integrate over those values, if they vary in time. The Mov voltage does NOT drop to zero, when conducting. Where did you learn about electricity?????? Of course some currents might be enough to blow the MOV, and that is specified in the documentation, as in how many WATTseconds blows it to pieces. Even then it still might provide protection, although only once, and then blow the mains fuse.
From: William Sommerwerck on 19 Jun 2010 19:32 >> Many years ago, PC and/or Byte (I forget which) used to test suppressors. If >> they failed to provide suppression, I assume the mag would have said so. > hillarious, PC magazine is your source for the lowdown on surge supression > devices? It was, 20 years ago. I don't think you get the point, though.
From: Jim Yanik on 19 Jun 2010 19:50 Sjouke Burry <burrynulnulfour(a)ppllaanneett.nnll> wrote in news:4c1d48fd$0$14115$703f8584(a)textnews.kpn.nl: > Jim Yanik wrote: >> "William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote in >> news:hvigjf$hg7$1(a)news.eternal-september.org: >> >>>> It is bud's job to constantly promote lies and myths. He is paid >>>> to promote plug-in protectors. Lying is what promoters may do. >>>> Where are those numeric specs? bud will never provide any. >>>> He cannot claim protection that does not exist. >>>> Where does that energy dissipate? bud cannot say. Otherwise >>>> he must admit that plug-in protectors are profit centers � not >>>> protection. >>> Uh... In the MOV? >>> >>> I thought the MOV conducted above its breakdown voltage (generally >>> around 300V), and the energy in the section of the AC waveform above >>> that voltage heated up the MOV. >>> >>> Am I missing something? >> >> Ohm's Law. >> If the MOV conducts at a low resistance,the power it dissipates will >> be minimal. >> Thus,the surge energy gets dissipated in whatever ground it's shunted >> to. >> >> > Bullshit. The Mov dissipates (Umov)*I*T, or > Total Energy=MOVvolts * Current * Seconds. > Or integrate over those values, if they vary in time. > The Mov voltage does NOT drop to zero, when conducting. I never said it did. the MOV voltage rating is the voltage when it changes state and drops to a low resistance to shunt the surge to GROUND. Now,how low a resistance in the conducting state is another matter. that's dependent on the MOV design/ratings. > Where did you learn about electricity?????? USAF PME School,1971. > Of course some currents might be enough to blow the MOV, yes,I said the MOV's dissipation would be "minimal",....compared to the total energy the MOV was passing to ground. what energy the MOV dissipates can easily be enough to blow it apart. I've seen it happen many times. But the MOV is not dissipating the total energy of the surge with it's suicide. > and that is specified in the documentation, as in how > many WATTseconds blows it to pieces. > Even then it still might provide protection, although > only once, and then blow the mains fuse. > > Of course,the fuse itself can arc over in a lightning strike,as it can exceed the typical 250v voltage rating of the fuse. -- Jim Yanik jyanik at localnet dot com
From: David on 19 Jun 2010 20:20 >> Bullshit. The Mov dissipates (Umov)*I*T, or >> Total Energy=MOVvolts * Current * Seconds. >> Or integrate over those values, if they vary in time. >> The Mov voltage does NOT drop to zero, when conducting. > > I never said it did. > the MOV voltage rating is the voltage when it changes > state and drops to a > low resistance to shunt the surge to GROUND. > Now,how low a resistance in the conducting state is > another matter. > that's dependent on the MOV design/ratings. > > >> Where did you learn about electricity?????? > > USAF PME School,1971. > >> Of course some currents might be enough to blow the MOV, > > yes,I said the MOV's dissipation would be > "minimal",....compared to the > total energy the MOV was passing to ground. > what energy the MOV dissipates can easily be enough to > blow it apart. > I've seen it happen many times. > But the MOV is not dissipating the total energy of the > surge with it's > suicide. > Jim Yanik > jyanik > at > localnet > dot com A MOV is somewhat like two back-to-back Zener diodes. It is a voltage clamp. You do not pass energy to ground, you pass current to ground just like you do with any load. The energy is totally dissipated in the MOV. David
From: Cydrome Leader on 20 Jun 2010 01:36
William Sommerwerck <grizzledgeezer(a)comcast.net> wrote: >>> Many years ago, PC and/or Byte (I forget which) used to test suppressors. > If >>> they failed to provide suppression, I assume the mag would have said so. > >> hillarious, PC magazine is your source for the lowdown on surge supression >> devices? > > It was, 20 years ago. I don't think you get the point, though. So what is the point? John Dvorak wrote a story about surge supressors and how they worked with his Cumulus 386 laptop and his CompuAdd 486sx tower? |