Surge Protectors
in [Repair]
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From: William Sommerwerck on 20 Jun 2010 08:01 "Cydrome Leader" <presence(a)MUNGEpanix.com> wrote in message news:hvk9c7$hrm$2(a)reader1.panix.com... > 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. >>> Hilarious, 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? The point is that they were performing lab tests on the suppressors. These tests included determining the clamping voltage. (I don't remember if they were tested to destruction.) The tests were presumably performed in accordance with industry-accepted standards.
From: bud-- on 20 Jun 2010 11:03 westom wrote: > On Jun 18, 3:55 pm, bud-- <remove.budn...(a)isp.com> wrote: >> Still missing - your source that says plug-in suppressors are NOT >> effective - just like westom. >> And westom has been looking for years. > > Your job is to promote plug-in protectors. Poor westom just keeps repeating the same lies, just like Josef Goebbels. If he had valid technical arguments he would not have to try to discredit those that expose his drivel. My only association with surge suppressors is that I have 2 of them. > You > cannot even post any spec numbers that define protection from each > type of surge. "Each type of surge" is more nonsense. SquareD, amongst others, does not have specs for "each type of surge". I provided a link to the specs I have provided in many threads -always ignored by westom, just like he ignores anything that conflicts with his religious belief in earthing. Apparently poor westom believes plug-in suppressors do not work, so he believes specs cannot possibly exist. > Destructive surges are hundreds of thousands of joules. Where does > that energy dissipate? Bud says that energy just magically > disappears. Poor westom's religious blinders prevent him from seeing what has been said in this thread, and numerous other threads. For incoming power wires, at about 6kV there is arc over from service busbars to the enclosure. After the arc stabilized the arc is hundreds of volts. The enclosure is connected to the earthing electrodes, so this dumps the vast majority of the incoming surge energy to earth. The neutral (in the US) is also always tied to the system ground at the service, so energy coming in on the neutral is directly earthed. Apparently that is all magic for westom. For a plug-in suppressor, the impedance of the branch circuit wiring greatly limits the current that can reach the suppressor. That greatly limits the energy that can reach the suppressor. NIST surge guru Martzloff looked at the energy that could reach the suppressor and was surprised that it was 35 joules or less. In most of his tests it was under 1 joule. That is with service surges up to the maximum that there is any reasonable probability of occurring. As Sjouke wrote, the MOV dissipates an energy equal to the clamp voltage times the current times the time. For a plug-in suppressor the current is very limited by the branch circuit impedance. And the time is very short - well under 100 microseconds. Fuses or circuit breakers do not provide protection because they are nowhere near fast enough - they won't open during a surge. Plug-in suppressors do not work primarily by earthing a surge - that reason poor westom believes they do not work. The IEEE surge guide explains how they work (starting pdf page40). They clamp the voltage on all wires to the ground at the suppressor. The voltage between all wires going to the protected equipment is safe for the protected equipment. Service panel suppressors also work by clamping the voltage - from hot wires to ground/earthing electrode (and hot-to-hot). Because the current can be up to 10,000A per hot (essentially zero probability of higher current, at least for houses) they can dissipate significant energy. But the vast majority of the energy is dissipated in the earth by the service earth electrode connection. The largest surges (lightning) are under 100 microseconds. Suppressors are readily available that will provide protection. With thousands of amps to the earthing electrode, the potential of the building "ground" can rise far above "absolute" earth potential. Neither service panel suppressors or plug-in suppressors protect by absorbing the surge energy. But in the process of protecting, some of the energy is absorbed. MOVs are fast enough to protect from the fastest surge. And if there was an extremely fast rise time it would be lowered by the impedance of the source wiring. All of the above is from NIST expert Martzloff, or other experts in the field. westom ignores it all. > Bud's citation Page 42 Figure 8 shows a surge earthed 8000 volts > destructively through a nearby TV. The lie repeated. Poor westom tries to make an example that explains protection say the opposite. The plug-in suppressor in this IEEE surge guide example protects the TV connected to it. It lowers the surge voltage at a second TV, although its job is to protect the equipment connected to it. It is a lie that the suppressor at TV1 damages TV2. The point of the illustration for the IEEE, and anyone who can think, is "to protect TV2, a second multiport protector located at TV2 is required." > Why? > The house did not earth via a 'whole > house' protector. In the IEEE example the surge comes in on the cable service, and high voltage results from a ground wire that is too long. westomn's favored service panel suppressor would provide absolutely *NO* protection. The IEEE says, for distant entrance points, that "the only effective way of protecting the equipment is to use a multiport [plug-in] protector." > A protector is > only as effective as its earth ground. westom's religious mantra protects him from conflicting thoughts (aka reality). westom is the poster child for cognitive dissonance. Still never explained - why aren't flying airplanes crashing every day when they are hit by lightning? > He is paid to > promote plug-in protectors. The lie repeated. But still never seen - any reliable source that agrees with westom that plug-in suppressors are NOT effective. Still never seen - answers to simple questions: - Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors? - Why does the NIST guide says plug-in suppressors are "the easiest solution"? - Why does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor? - How would a service panel suppressor provide any protection in the IEEE example, page 42? - Why does the IEEE guide say for distant service points "the only effective way of protecting the equipment is to use a multiport [plug-in] protector"? - Why did Martzloff say in his paper "One solution. illustrated in this paper, is the insertion of a properly designed [multiport plug-in surge suppressor]"? - Why does Dr. Mansoor support multiport plug-in suppressors? - Why does "responsible" manufacturer SquareD says "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use"? - Why don�t favored SquareD service panel suppressors list "each type of surge"? For real science read the IEEE and NIST surge guides. Both say plug-in suppressors are effective. The IEEE guide, in particular, is really an excellent source of information from a reliable source. I really recommend anyone who is interested in surge protection read it. -- bud--
From: westom on 20 Jun 2010 11:39 On Jun 19, 8:20 pm, "David" <some...(a)somewhere.com> wrote: > 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. Now do the numbers. How does that hundred joule MOV absorb energy that is hundreds of thousands of joules? You are reciting the myths promoted by plug-in protectors. For example, how to get the protector to last longer? Increase its joules rating. Then the entire protector absorbs "LESS" energy. Protector that absorbs a surge is the urban myth promoted by those who never learned this stuff. This 100 years old technology. So that energy dissipates harmlessly in earth - not inside the building - the protector must make a short ('less than 10 foot') connection to single point earth ground. No protector is protection. None. A protector is only a connecting device. Either it connects a 20,000 amp surge harmlessly to earth. Or it does nothing. A protector is only as effective as its earth ground - which those educated by advertising never learn.
From: westom on 20 Jun 2010 11:54 On Jun 19, 12:25 pm, Jeffrey D Angus <jan...(a)suddenlink.net> wrote: > What the plug-in suppressors rely on is the impedance (generally > inductive) in the house wiring to limit the rise time of thesurgeuntil the circuit breaker (or fusable parts) have time to > react by opening up. No surge protector is too slow. That wiring is why plug-in protectors are not earthed. And why Bud will not discuss wire impedance and earth ground. bud's citation Page 42 Figure 8 shows a plug-in protecting earthing a surge 8000 volts destructively through a nearby TV. He hopes you do not grasp the point in his IEEE citation. So let's put numbers to it. Let's say the plug-in protector and TV are 50 feet of wire from the breaker box. That means it is less than 0.2 ohms resistance. And maybe 120 ohms impedance. So that protector will earth a trivial 100 amp surge? 100 amps times 120 ohms means the protector and TV are at maybe 12,000 volts. Why did the protector earth that surge 8000 volts through the TV? AC electric wire impedance meant the surge had to obtain earth 8000 volts destructively through the TV. Why do telcos all over the world not waste money on bud's plug-in protectors? Because telcos can suffer about 100 surges per thunderstorm. So telcos put a protector as close to earth ground as possible. And up to 50 meters separated from electronics. That separation means increases protection. Why? See numbers in that above paragraph. Whereas an average homeowner suffers maybe one surge every seven years. A telco suffers at least 100 with each storm. So telcos do not locate protectors adjacent to electronics. Telcos always earth 'whole house' protectors for the same reasons it was done 100 year ago a low impedance connection to single point ground. Protector must be as close to earth as possible (lowest impedance to single point ground) AND works best when distant from electronics. Learn that no protector works by absorbing energy. That is why the protector too close to appliances and too far from earth ground can even earth that surge 8000 volts destructively through a nearby TV. A majority only believe the advertising myths - that protectors magically make hundreds of thousands of joules just magically disappear. That myth sells plug-in protectors. Any location that cannot have damage (ie munitions dumps) instead earths a 'whole house' protector. Then energy never enters a building. Then energy harmlessly dissipates outside the building in earth ground. Protection is always about where energy dissipates. IOW a protector is only as effective as its earth ground. A reality that would harm bud's profit margins.
From: Jim Yanik on 20 Jun 2010 14:28
"David" <someone(a)somewhere.com> wrote in news:hvjmsg$4v4$1(a)news.eternal- september.org: > >>> 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. no,it's not. it does not "clamp" the voltage. > 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 > > > totally wrong. Wiki has a nice article on metal-oxide varistor,I suggest you read it. -- Jim Yanik jyanik at localnet dot com |