Surge Protectors
in [Repair]
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From: Jim Yanik on 20 Jun 2010 14:30 "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. -- Jim Yanik jyanik at localnet dot com
From: David on 20 Jun 2010 15:27 >> >> 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 Jim, I am not going to get into a flame war over this topic. Maybe you should check this out: <http://www.cliftonlaboratories.com/metal_oxide_varistor_(mov).htm> David
From: Jeffrey D Angus on 20 Jun 2010 15:39 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. Jeff -- �Egotism is the anesthetic that dulls the pain of stupidity.� Frank Leahy, Head coach, Notre Dame 1941-1954 http://www.stay-connect.com
From: Jim Yanik on 20 Jun 2010 21:29 "David" <someone(a)somewhere.com> wrote in news:hvlq34$3ic$1(a)news.eternal- september.org: > >>> >>> 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 > > Jim, I am not going to get into a flame war over this topic. > Maybe you should check this out: > ><http://www.cliftonlaboratories.com/metal_oxide_varistor_(mov).htm> > > David > > did you even READ the wiki article? it appears not. -- Jim Yanik jyanik at localnet dot com
From: Jim Yanik on 20 Jun 2010 21:40
"David" <someone(a)somewhere.com> wrote in news:hvlq34$3ic$1(a)news.eternal- september.org: > >>> >>> 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. Uh,"passing current to ground" IS passing energy to ground. >>> >>> David >>> >>> >>> >> >> totally wrong. >> Wiki has a nice article on metal-oxide varistor,I suggest >> you read it. >> >> -- >> Jim Yanik >> jyanik >> at >> localnet >> dot com > > Jim, I am not going to get into a flame war over this topic. > Maybe you should check this out: > ><http://www.cliftonlaboratories.com/metal_oxide_varistor_(mov).htm> > > David > > http://en.wikipedia.org/wiki/Metal_oxide_varistor Varistors can absorb part of a surge. How much effect this has on risk to connected equipment depends on the equipment and details of the selected varistor. Varistors do not absorb a significant percentage of a lightning strike, as energy that must be conducted elsewhere is many orders of magnitude greater than what is absorbed by the small device. -- Jim Yanik jyanik at localnet dot com |