Surge Protectors
in [Repair]
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From: bud-- on 21 Jun 2010 11:34 Jim Yanik wrote: > "William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote in > news:hvl00i$lma$1(a)news.eternal-september.org: > >> "Cydrome Leader" <presence(a)MUNGEpanix.com> wrote in message >> news:hvk9c7$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. >> >> >> > > "clamping" is a misuse of the word WRT surge protectors. > It misleads people,as in "david" s post. > > "trigger voltage" might more accurate. MOVs have a smooth, but nonlinear, curve from not conducting at low voltage to high conduction current at higher voltages. They do not "trigger" like a neon light. And the voltage across the MOV does not suddenly decrease, like it would in a neon light (you probably didn't say it did). "Clamping" is a widely used term, including the wiki article on MOVs. (Gas discharge tubes are like a neon light, and do trigger.) One of the parameters for a MOV is MCOV (maximum continuous operating voltage) which is the voltage at which the current is 1 mA. The increase in current is smooth (but very non-linear) above the MCOV, just like it was smooth (and non-linear) below the MCOV. (When the MCOV for a MOV decreases 10% it is the defined end of life for a MOV - referred to in the wiki article.) A MOV is very much like back-to-back Zener diodes, but does not clamp as sharply. But MOVs have huge current capacity in a small package. The clamp voltage that is usually cited is the UL let through voltage (UL calls it something a little different). This is the voltage at a specified test surge current. If the surge current goes up, the let through voltage will be higher (in a non-linear way). -- bud--
From: Jeff Liebermann on 21 Jun 2010 12:12 On Sun, 20 Jun 2010 14:39:27 -0500, Jeffrey D Angus <jangus(a)suddenlink.net> wrote: >David wrote: >> <http://www.cliftonlaboratories.com/metal_oxide_varistor_(mov).htm> > >Amazing coincidence that they act much like the old NE-2 neon >bulb across the antenna leads of old receivers for protection. > >They would conduct around 65 volts and suddenly go to near >zero impedance, safely shunting what ever energy on the antenna >line to ground. > >And although most receiver inputs couldn't handle a steady state >of 65 volts (or 130 vpp), they could handle them long enough for >the neon bulb to conduct and then shunt them to ground. We used to test our radios with 117vac on the antenna terminals. While not a required test, it happened often enough that it was worth testing and protecting. The AC plug to PL-259 test cable on my cable rack generated quite a few odd questions. Neon lamps, MOV's, back to back diodes, PIN diodes, and such are generally a bad idea in high RF environments. Any non-linear device between the antenna and the RF amp is going to act like a mixer and create the dreaded intermodulation products. MOV's and diodes are particularly bad because they start to slightly conduct at nearly zero voltage, and increase exponentially with increasing signal. The MOV also has 100-1000pf of unstable and unpredictable capacitance, which is not a good thing on the antenna input. The closest approximation of an ideal protection device are the one-time gas filled spark gaps used in lightning protectors. No conduction at all until they arc over. Then, they're dead. Question: What's the peak to peak output voltage of a 50 watt transmitter into 50 ohms? Answer: V = 2.828 * 50^2 / 50 = 141 volts p-p Now, do you REALLY want a device that conducts at 65 volts across the xmitter antenna terminals? I actually tried a varistor across the antenna terminals of an HF 150w PEP xmitter and confirmed the big bang theory. Hint: Things work differently at 60Hz than at RF frequencies. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: GS on 21 Jun 2010 12:16 On Jun 20, 1:36 am, Cydrome Leader <prese...(a)MUNGEpanix.com> wrote: > William Sommerwerck <grizzledgee...(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? My news reader sees a problem in these postings .. Mark Waller wrote an article for Byte. I have his book PC Power Protection from 1988. Great reading. I should also have that mag article if anybody is interested. I should look it up. From worrying too much about protection, Mark is now a Family Therapist. greg
From: westom on 21 Jun 2010 12:49 On Jun 21, 11:19 am, bud-- <remove.budn...(a)isp.com> wrote: > Poor westom's religious blinders prevent him from reading what gets > written. I certainly have written about wire impedance in this thread. Bud promotes plug-in protectors. It is his job. Either that protector connects energy harmlessly to earth. Energy absorbed without damage. Or energy is inside the building - bud's IEEE guide Page 42 Figure 8 - hunting for earth destructively via appliances. 8000 volts destructively through the TV because bud's miracle protector cannot absorb destructive surges. bud's NIST citation also describes bud's "profit center" protectors: > A very important point to keep in mind is that your surge protector will work by diverting the > surges to ground. The best surge protection in the world can be useless if grounding is > not done properly. No earth ground (bud's high profit protectors) means no effective protection. Even the NIST says so. All of bud's citations say that. Meanwhile IEEE Standards (the Red Book) - where the IEEE makes all recommendations - state what is always necessary for surge protection - and what bud denies: > In actual practice, lightning protection is achieve by the process of interception of lightning produced > surges, diverting them to ground, and by altering their associated wave shapes. Or IEEE Emerald Book: > It is important to ensure that low-impedance grounding and bonding connections exist among the > telephone and data equipment, the ac power system's electrical safety-grounding > system, and > the building grounding electrode system. ... > Failure to observe any part of this grounding requirement may result in hazardous potential being > developed between the telephone (data) equipment and other grounded items that personnel may > be near or might simultaneously contact. Protection is always about where energy dissipates. That means an effective protector connects short (ie 'less than 10 feet') to single point earth ground. But somehow bud's protectors magically make energy just disappear? It is what he is paid to promote. It is why he gets angry. Reality would harm profits. Surge protection means energy dissipates harmlessly in earth; outside the building. A protector without that dedicated and short connection to earth does not claim protection in its numeric specs - as bud tacitly admits. So bud's protector magically makes that energy disappear? That is also what bud tacitly claims.
From: bud-- on 21 Jun 2010 13:40
westom wrote: > On Jun 21, 11:19 am, bud-- <remove.budn...(a)isp.com> wrote: >> Poor westom's religious blinders prevent him from reading what gets >> written. I certainly have written about wire impedance in this thread. > > Bud promotes plug-in protectors. It is his job. westom just continues to repeat the same lies - a la Goebbels. And the same misrepresentations - a la religious fanaticism. All the sources westom uses, including even his favorite manufacturers, say plug-in suppressors are effective. In particular, the IEEE and NIST surge guides both say plug-in suppressors are effective. Links have been provided to these reliable sources. There are 259,615,938 other web sites, including 23,843,032 by lunatics, and westom can't find another lunatic that says plug-in suppressors are NOT effective. Also still missing - 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 aren't airplanes crashing daily when they get hit by lightning (or do they drag an earthing chain)? - 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"? Why can't you answer simple questions westom???? -- bud-- |