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Sci.Electronics.Basics -> Surge / Ground / Lightning
There are 215 messages in this thread.
You are currently looking at messages 180 to 200.
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Author: VWWallDate: 14:37 07-05-08
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fl_fly_boy@yahoo.com wrote:
>> I think the UL requires only that the MOVs don't start a fire when
>> exposed to conditions which cause their break-down. They don't rate
>> their ability to function as "surge protectors".
>
>
> UL evaluates surge suppressors for fire, electric shock and personal
> injury hazards, and also measures and categorizes the devices for how
> much voltage they can "clamp," thus preventing excess voltage from
> passing through to electronic equipment. UL refers to this as a
> "suppressed voltage rating," with ranges from 330V (volts) to 4000V.
> Believe it or not, the lower the rating, the better the protection.
How can one find this rating for a particular device?
> Whatever surge suppression protection you're looking for, make sure
> the surge suppressor has been tested and Listed to the stringent
> requirements of UL 1449, the Standard for Transient Voltage Surge
> Suppressors.
>
> http://www.ul.com/consumers/surge.html
"The unpredictable nature of surges makes it difficult to suppress them;
you never know when, how long or how powerful they will be. In some
cases, a surge may have a higher energy level than the device can
handle. When this happens, the surge suppressor may be damaged and lose
its ability to provide protection against future surges."
I'm happy to see that UL agrees! They don't seem to put any evaluation
of this parameter, unless the "suppressed voltage rating" includes the
Jules rating of the MOVs.
> http://ulstandardsinfonet.ul.com/tocs/tocs.asp?doc=s&fn=1449.toc
Thanks for the reference.
--
Virg Wall, P.E.
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Author: VWWallDate: 14:50 07-05-08
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VWWall wrote:
<see original post>
>> http://www.ul.com/consumers/surge.html
>
> "The unpredictable nature of surges makes it difficult to suppress them;
> you never know when, how long or how powerful they will be. In some
> cases, a surge may have a higher energy level than the device can
> handle. When this happens, the surge suppressor may be damaged and lose
> its ability to provide protection against future surges."
>
> I'm happy to see that UL agrees! They don't seem to put any evaluation
> of this parameter, unless the "suppressed voltage rating" includes the
> Jules rating of the MOVs.
This should read "Joules". See:
http://en.wikipedia.org/wiki/Varistor
for some useful information.
--
Virg Wall, P.E.
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Author: Michael A. TerrellDate: 14:58 07-05-08
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trader4@optonline.net wrote:
>
> LOL Haven't you seen W_ in action before? This is one of his
> standard rants repeated many times. According to W_ any damage from
> lightning or surges MUST be do to HUMAN failure.
Yes, I've seen that, and more. That's why I refute his crap. If he
isn't refuted, people who don't know any better will believe him.
--
http://improve-usenet.org/index.html
Use any search engine other than Google till they stop polluting USENET
with porn and junk commercial SPAM
If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm
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Author: VWWallDate: 15:05 07-05-08
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Michael A. Terrell wrote:
> trader4@optonline.net wrote:
>> LOL Haven't you seen W_ in action before? This is one of his
>> standard rants repeated many times. According to W_ any damage from
>> lightning or surges MUST be do to HUMAN failure.
>
>
>
> Yes, I've seen that, and more. That's why I refute his crap. If he
> isn't refuted, people who don't know any better will believe him.
Just ask him about using a 3 1/2 digit VOM to check out those lousy ATX
power supplies thet everyone is fostering on us. ;-)
--
Virg Wall
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Author: TantalustDate: 15:05 07-05-08
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"w_tom" <w_tom1@usa.net> wrote in message
news:b224d456-f25c-4c73-bfe5-c546c7871592@e53g2000hsa.googlegroups.com...
> On May 6, 2:45 pm, Sjouke Burry <burrynulnulf...@ppllaanneett.nnlll>
> wrote:
>> Can you trim W_tom with that?? Or is he incurable?
>
> He is incurable as long as others post outright lies and myths while
> denying what really provides surge protection. Now to discuss what is
> relevant.
What's becoming more relevant here every day is your mental illness. . . . .
along with your terrible OCD disadvantage, constantly referring to yourself
in the third-person is pointing to a flourishing
Depersonalization/Dissociative Identity Disorder. You can look it up.
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Author: Michael A. TerrellDate: 15:35 07-05-08
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VWWall wrote:
>
> Michael A. Terrell wrote:
> > trader4@optonline.net wrote:
> >> LOL Haven't you seen W_ in action before? This is one of his
> >> standard rants repeated many times. According to W_ any damage from
> >> lightning or surges MUST be do to HUMAN failure.
> >
> >
> >
> > Yes, I've seen that, and more. That's why I refute his crap. If he
> > isn't refuted, people who don't know any better will believe him.
>
> Just ask him about using a 3 1/2 digit VOM to check out those lousy ATX
> power supplies thet everyone is fostering on us. ;-)
He's no better at choosing a meter than he is at thinking.
--
http://improve-usenet.org/index.html
Use any search engine other than Google till they stop polluting USENET
with porn and junk commercial SPAM
If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm
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Author: flyboyDate: 16:05 07-05-08
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On May 7, 2:37=A0pm, VWWall <vw...@large.invalid> wrote:
> fl_fly_...@yahoo.com wrote:
> >> I think the UL requires only that the MOVs don't start a fire when
> >> exposed to conditions which cause their break-down. =A0They don't rate
> >> their ability to function as "surgeprotectors".
>
> > UL evaluatessurgesuppressors for fire, electric shock and personal
> > injury hazards, and also measures and categorizes the devices for how
> > much voltage they can "clamp," thus preventing excess voltage from
> > passing through to electronic equipment. UL refers to this as a
> > "suppressed voltage rating," with ranges from 330V (volts) to 4000V.
> > Believe it or not, the lower the rating, the better the protection.
>
> How can one find this rating for a particular device?
Look for ul1449 330v or 400 for example, or surge voltage rating SVR
330v or Clamping Category 330v
>
> > Whateversurgesuppression protection you're looking for, make sure
> > thesurgesuppressor has been tested and Listed to the stringent
> > requirements of UL 1449, the Standard for Transient VoltageSurge
> > Suppressors.
>
> >http://www.ul.com/consumers/surge.html
>
> "The unpredictable nature of surges makes it difficult to suppress them;
> you never know when, how long or how powerful they will be. In some
> cases, asurgemay have a higher energy level than the device can
> handle. When this happens, thesurgesuppressor may be damaged and lose
> its ability to provide protection against future surges."
MOV=92s and surge protectors are like tires on your car, the more you
use them the shorter useful life, mistreat them, the shorter the
useful life, too small or light weight the shorter the useful life.
Ul 1449 certification take care of the too small or light weight.
Proper selection for problem locations is the key to protection.
>
> I'm happy to see that UL agrees! =A0They don't seem to put any evaluation
> of this parameter, unless the "suppressed voltage rating" includes the
> Jules rating of the MOVs.
Don=92t pay attention to joules on surge protectors, no standard to
measure, a better and recommended rating is =93Peak Surge Current=94 the
higher the better.
>
> >http://ulstandardsinfonet.ul.com/tocs/tocs.asp?doc=3Ds&fn=3D1449.toc
>
> Thanks for the reference.
>
> --
> Virg Wall, P.E.
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Author: Rich GriseDate: 18:24 07-05-08
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On Mon, 05 May 2008 19:21:16 +0300, Tzortzakakis Dimitrios wrote:
> Ï "Tantalust" <Tantalust@paradise.net> Ýãñáøå óôï ìÞíõìá
> news:RPidnaZzhcrV0oXVnZ2dnUVZ_hadnZ2d@comcast.com...
>> "NB" <nobuyout@gmail.com> wrote in message
>> news:b53f2fef-00bd-40d0-9ac1-c69b3bcadf52@x41g2000hsb.googlegroups.com...
>>> Who is W_TOM and why has he appeared in every single thread that has
>>> contained those keywords since 2001???
>>
>> He an obsessive-compulsive disorder victim, apparently driven by some kind
>> of bizarre fetish involving ground rods.
>>
> What kind of ground rods? I prefer steel core, copper clad ones:-) I even
> have the special heavy hammer>
I saw one in one of the "Popular this-n-that" mags, that used a piece of
copper pipe, with a hose fitting on the end. You point the pipe at the
ground, turn on the hose, and the water digs its hole for it. Then, you
can take the hose fitting off, cap the pipe, and have a pretty decent
ground stake.
Maybe it was one of the ham mags.
Cheers!
Rich
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Author: w_tomDate: 20:04 07-05-08
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On May 7, 7:27 am, trad...@optonline.net wrote:
> And as usual, W_'s statement taken at face value is wrong and/or
> misleading. A simple check of history shows Saddam did in fact have
> WMDs for years, because they were used in war and against his own
> people.
Read Duelfer's report. Learn facts before posting. When David
Kay's report said WMDs did not exist, then extremists had Kay's report
withheld hoping that Charles Duelfer=92s report would say otherwise.
Instead, Duelfer=92s report said what Kay's report said - and more.
Those WMDs did not exist.
trader should first learn before knowing. trader's constant
bickering is directly traceable to knowledge with first learning
facts. Another indication of that, his problem, are posts full of
insults rather than technical facts. When will trader post a technical
facts or citation? trader even denies what was well documented about
Saddam's WMDs. No wonder he also posts insults that only Rush
Limbaugh would be proud of.
Meanwhile, a protector is only as effective as its earth ground
which is why one 'whole house' protector is *routine* for effective
household surge protection. Which is why responsible homeowners also
inspect their primary surge protection:
http://www.tvtower.com/fpl.html
trader also denies this despite a long list of industry professionals
that trader never bothered to learn from.
Another professional standard contradicts naysayers such as trader.
IEEE Green Book (IEEE Std 142) entitled 'Static and Lightning
Protection Grounding':
> Lightning cannot be prevented; it can only be intercepted or
> diverted to a path which will, if well designed and constructed,
> not result in damage. Even this means is not positive,
> providing only 99.5-99.9% protection. ...
> Still, a 99.5% protection level will reduce the incidence of direct
> strokes from one stroke per 30 years ... to one stroke per
> 6000 years ...
Significantly effective is only one 'whole house' protector.
Protector for about $1 per protected appliance. How much for the
ineffective plug-in protector? $25 or $150 per protected
appliance. Where does that plug-in protector even claim to protect
from typically destructive surges? No plug-in manufacturer
specification exists. It does not even claim to protect from the
typically destructive sruge. IEEE is quite blunt about effective
protection from a properly earthed 'whole house' protector. Unlike
trader, I even provide numbers.
trader never read industry standards. Unnecessary. trader
automatically knows without first learning.
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Author: w_tomDate: 20:09 07-05-08
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On May 7, 2:37 pm, VWWall <vw...@large.invalid> wrote:
> How can one find this rating for a particular device?
UL makes no effort to measure a protector's protective ability. In
fact, protectors can completely fail during a UL certification test
and still obtain UL approval. It failed without emitting sparks or
flame; therefore UL approved.
Approval may be obtained by undersizing MOV's thermal fuses so that
a protector will disconnect MOVs faster during a surge; leave the
appliance to fend for itself. Undersized surge protector simply
disconnects faster to obtain UL1449 approval. How might it get that
approval? Provide even less protection so as to not spit flame.
Also required for UL approval is total number of joules. That says
nothing about how many joules actually participate in protection.
Typically, plug-in protectors use as little as 1/3rd and never more
than 2/3rd of its joules for protection. If a protector is also for
cable, telephone, network, etc, then that protector may use even less
joules during protection.
A 'whole house' protector uses all joules during all types of
surges. What happens when more joules actually participate in
protection? Well, doubling the numbers of 'used' joules typically
increases a protector=92s life expectancy by a factor of eight. As
joules increase, the life expectancy of the protector increases
exponentially. As joules increase, more energy gets dissipated in
earth and less energy gets dissipated inside the protector. Increase
joules to absorb less energy and to exponentially increase protector's
life expectancy.
Minimal 'whole house' protector for a home is 1000 joules and 50,000
amp surges. In locations where surges occur more frequently, a larger
joule protector is installed. Increased joules means increases
protector life expectancy.
How effective are 'whole house' protectors? Well, a friend suffered
when the 33,000+ volt transmission line fell upon his 4000 volt
distribution line. Literally everyone powered from that B phase had
electric meters explode up to 30 feet from their pans. Many had
damage to plug-in protectors and to powered off appliances plugged
into those protectors. But my friend suffered no damage, except to a
meter that exploded off his building. He had a properly earthed
'whole house' protector. A protector is not rated to provide that
protection. But properly installed protectors with sufficient joules
will provide more protection than rated.
Which protectors actually provide better protection? Products from
a list of responsible manufacturers such as Intermatic, Square D,
Siemens, Polyphaser, GE, Cutler-Hammer, Keison, and Leviton.
Specifically not on that list are APC, Tripplite, Belkin, and Monster
Cable.
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Author: Mike TomlinsonDate: 20:49 07-05-08
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w_tom <w_tom1@usa.net> wrote:
> Also required for UL approval is total number of joules. That says
>nothing about how many joules actually participate in protection.
>Typically, plug-in protectors use as little as 1/3rd and never more
>than 2/3rd of its joules for protection.
How does a protector decide how many of its joules to use? :-)
Nick
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On 8 May 2008 07:12:33 -0400, nicksanspam@ece.villanova.edu wrote:
>w_tom <w_tom1@usa.net> wrote:
>
>> Also required for UL approval is total number of joules. That says
>>nothing about how many joules actually participate in protection.
>>Typically, plug-in protectors use as little as 1/3rd and never more
>>than 2/3rd of its joules for protection.
>
>How does a protector decide how many of its joules to use? :-)
>
>Nick
Bwhahahahahaha!
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On May 7, 2:37 pm, VWWall <vw...@large.invalid> wrote:
> fl_fly_...@yahoo.com wrote:
> >> I think the UL requires only that the MOVs don't start a fire when
> >> exposed to conditions which cause their break-down. They don't rate
> >> their ability to function as "surgeprotectors".
> > UL evaluatessurgesuppressors for fire, electric shock and personal
> > injury hazards, and also measures and categorizes the devices for how
> > much voltage they can "clamp," thus preventing excess voltage from
> > passing through to electronic equipment. UL refers to this as a
> > "suppressed voltage rating," with ranges from 330V (volts) to 4000V.
> > Believe it or not, the lower the rating, the better the protection.
> How can one find this rating for a particular device?
Look for ul1449 330v or 400 for example, or surge voltage rating SVR
330v or Clamping Category 330v
> > Whateversurgesuppression protection you're looking for, make sure
> > thesurgesuppressor has been tested and Listed to the stringent
> > requirements of UL 1449, the Standard for Transient VoltageSurge
> > Suppressors.
> >http://www.ul.com/consumers/surge.html
> "The unpredictable nature of surges makes it difficult to suppress them;
> you never know when, how long or how powerful they will be. In some
> cases, asurgemay have a higher energy level than the device can
> handle. When this happens, thesurgesuppressor may be damaged and lose
> its ability to provide protection against future surges."
MOV=92s and surge protectors are like tires on your car, the more you
use them the shorter useful life, mistreat them, the shorter the
useful life, too small or light weight the shorter the useful life.
Ul 1449 certification take care of the too small or light weight.
Proper selection for problem locations is the key to protection.
> I'm happy to see that UL agrees! They don't seem to put any evaluation
> of this parameter, unless the "suppressed voltage rating" includes the
> Jules rating of the MOVs.
Don=92t pay attention to joules on surge protectors, no standard to
measure, a better and recommended rating is =93Peak Surge Current=94 the
higher the better.
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Author: bud--Date: 10:52 08-05-08
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fl_fly_boy@yahoo.com wrote:
> On May 7, 2:37 pm, VWWall <vw...@large.invalid> wrote:
>> fl_fly_...@yahoo.com wrote:
>>>> I think the UL requires only that the MOVs don't start a fire when
>>>> exposed to conditions which cause their break-down. They don't rate
>>>> their ability to function as "surgeprotectors".
>>> UL evaluatessurgesuppressors for fire, electric shock and personal
>>> injury hazards, and also measures and categorizes the devices for how
>>> much voltage they can "clamp," thus preventing excess voltage
from
>>> passing through to electronic equipment. UL refers to this as a
>>> "suppressed voltage rating," with ranges from 330V (volts) to
4000V.
>>> Believe it or not, the lower the rating, the better the protection.
That is a quote from UL. Contrast that with Martzloff:
"The fact of the matter is that nowadays, most electronic appliances
have an inherent immunity level of at least 600 V to 800 V, so that the
clamping voltages of 330 V widely offered by TVSS [surge suppressor]
manufacturers are really not necessary. Objective assessment of the
situation leads to the conclusion that the 330 V clamping level,
promoted by a few manufacturers, was encouraged by the promulgation of
UL Std 1449, showing that voltage as the lowest in a series of possible
clamping voltages for 120 V circuits. Thus was created the downward
auction of 'lower is better' notwithstanding the objections raised by
several researchers and well-informed manufacturers. One of the
consequences of this downward auction can be premature ageing of TVSS
that are called upon to carry surge currents as the result of relatively
low transient voltages that would not put equipment in jeopardy."
>> How can one find this rating for a particular device?
>
> Look for ul1449 330v or 400 for example, or surge voltage rating SVR
> 330v or Clamping Category 330v
I believe it is required by UL to be on the package or literature.
>
>>> Whateversurgesuppression protection you're looking for, make sure
>>> thesurgesuppressor has been tested and Listed to the stringent
>>> requirements of UL 1449, the Standard for Transient VoltageSurge
>>> Suppressors.
>>> http://www.ul.com/consumers/surge.html
>> "The unpredictable nature of surges makes it difficult to suppress them;
>> you never know when, how long or how powerful they will be. In some
>> cases, asurgemay have a higher energy level than the device can
>> handle. When this happens, thesurgesuppressor may be damaged and lose
>> its ability to provide protection against future surges."
>
> MOV’s and surge protectors are like tires on your car, the more you
> use them the shorter useful life, mistreat them, the shorter the
> useful life, too small or light weight the shorter the useful life.
> Ul 1449 certification take care of the too small or light weight.
> Proper selection for problem locations is the key to protection.
>
>> I'm happy to see that UL agrees! They don't seem to put any evaluation
>> of this parameter, unless the "suppressed voltage rating" includes
the
>> Jules rating of the MOVs.
>
> Don’t pay attention to joules on surge protectors, no standard to
> measure, a better and recommended rating is “Peak Surge Current” the
> higher the better.
I would like to know the Joule ratings. The problem, as you say, is
there is no standard way to measure the energy rating and some
manufacturers apparently use questionable ratings. That has led some
other reputable manufacturers, like SquareD, to not include Joule ratings.
Peak surge current is directly related to the energy rating. w_'s
recommended 50,000A surge current rating is way beyond what you will get
at a service panel, but it represents a high energy rating which means
long life.
--
bud--
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Author: bud--Date: 12:11 08-05-08
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w_tom wrote:
> On May 7, 2:37 pm, VWWall <vw...@large.invalid> wrote:
>> How can one find this rating for a particular device?
>
> UL makes no effort to measure a protector's protective ability.
Cuttler Hammer says you are wrong.
http://tinyurl.com/63594d
>
> Approval may be obtained by undersizing MOV's thermal fuses so that
> a protector will disconnect MOVs faster during a surge; leave the
> appliance to fend for itself.
Of course that applies to service panel and plug-in suppressors. But CH
says a suppressor has to have tested functionality (above).
w_ just buys cheap Chinese knock offs, so his suppressors fail regularly.
>
> Also required for UL approval is total number of joules.
Provide a cite. Why does your favored manufacturer SquareD not provide
Joule ratings?
>
> A 'whole house' protector uses all joules during all types of
> surges.
Depends on the surge.
>
> How effective are 'whole house' protectors? Well, a friend suffered
> when the 33,000+ volt transmission line fell upon his 4000 volt
> distribution line. Literally everyone powered from that B phase had
> electric meters explode up to 30 feet from their pans. Many had
> damage to plug-in protectors and to powered off appliances plugged
> into those protectors. But my friend suffered no damage, except to a
> meter that exploded off his building. He had a properly earthed
> 'whole house' protector. A protector is not rated to provide that
> protection. But properly installed protectors with sufficient joules
> will provide more protection than rated.
Neither service panel or plug-in suppressors will survive extended
overvoltage. It rapidly kills MOVs. w_ is using anecdotal evidence
(with no cite) to suggest service panel suppressors protect from crossed
power lines. More lunacy.
>
> Which protectors actually provide better protection? Products from
> a list of responsible manufacturers such as Intermatic, Square D,
> Siemens, Polyphaser, GE, Cutler-Hammer, Keison, and Leviton.
Being responsible, they all make plug-in suppressors except SquareD.
SquareD, for the ‘best’ service panel suppressor, says "electronic
equipment may need additional protection by installing plug-in
[suppressors] at the point of use."
Still missing - a link to another lunatic that says plug-in suppressors
are NOT effective.
Still missing – answers to embarrassing questions:
- Why do the only 2 examples of surge suppression in the IEEE guide use
plug-in suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest
solution"?
- Why do all but one of w's "responsible manufacturers" make plug-in
suppressors?
- Why does SquareD say in addition to their "whole house" suppressors
"electronic equipment may need additional protection" from plug-in
suppressors.
- Why aren't airplanes crashing daily when they get hit by lightning (or
do they drag an earthing chain)?
For accurate information read the IEEE and NIST guides. Both say plug-in
suppressors are effective.
--
bud--
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Author: bud--Date: 12:19 08-05-08
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VWWall wrote:
> bud-- wrote:
>> VWWall wrote:
>>> trader4@optonline.net wrote:
>>>
>>>> "New thermally enhanced MOVs help protect a wide variety of
low-power
>>>> systems against damage caused by over-current, over-temperature and
>>>> over-voltage faults, including lightning strikes, electrostatic
>>>> discharge (ESD) surges, loss of neutral, incorrect input voltage and
>>>> power induction.
>>>
>>> I had a microwave oven that had a MOV across the 120V line ahead of
>>> the power switch. The other side of the 120/240 20A circuit supplied
>>> a refrigerator. The loss of the neutral applied a good part of the
>>> 240V across the MOV when the refrigerator attempted to start.
>>>
>>> The MOV didn't last long! It would probably have been OK on the load
>>> side of the switch.
>>
>> Using a MOV to protect against loss of neutral (in the article) is
>> rather futile. Sustained overvoltage will rapidly kill them. Although
>> if the protected load was across the MOV and a fuse was ahead of both
>> protection may work. Would be interesting why the MOV was ahead of the
>> switch.
>
> Good question. In the MW oven case, the switch was a relay controlled
> by the timer circuit. It was probably easier to locate the MOV at the
> line input.
>
> I have seen cases with a "blown" MOV and the circuit protector tripped.
> The MOV, if it tripped the protector, may have saved the following
> circuits from the over-voltage condition for a longer period of time. I
> haven't tried to calculate the conditions under which this would work.
Normal MOV failure is by high current and overheating (as below). A fuse
may provide protection. Plug-in suppressors likely use the heat as part
of the disconnect. For overvoltage, the disconnect would have to survive
the higher voltage.
>>> I know that refrigerators should be alone on a "home run"
circuit,
>>> and neutrals shouldn't be connected with wire nuts, but that wasn't
>>> how it was!
>>>
>>> My only complaint with some plug-in protectors is that the MOVs are
>>> often much too small. I've also seen some with only a line-line MOV.
>
> As you know, MOVs lose their capacity each time a "spike" causes them to
> conduct. This reduces the remaining capability to handle "surges".
You may already know all of this -
MOVs are damaged by heat from energy dissipated in their clamping
action. The defined end of life of a MOV is when the voltage that
produces a 1mA current decreases 10%. At that point the MOV is still
clamping the voltage across it. Further dissipation continues to lower
the voltage until the MOV conducts at ‘normal’ voltages and goes into
thermal runaway. For surge suppressors, UL required protection
disconnects the MOV when it overheats. It should still be clamping at
that point.
The energy (Joule) rating is for a single event. If the individual hits
are far below the rating, the cumulative energy rating is far above the
single event rating. High ratings give longer life than you might expect.
Service panel and plug-in suppressors do not protect by absorbing
energy. But they absorb energy in the process of protecting.
>> I would only buy one with fairly high ratings (which are readily
>> available).
>
> True, but some are marketed as "surge protected" with minimal capacity.
> I've replaced the MOVs in several cheap multiple socket strips with
> higher rated MOVs from Radio Shack.
>
>> UL, as far as I know, requires MOVs to be L-N, L-G, N-G. I thought
>> that was the standard since the start, which w_ said was 1985.
>
> I think the UL requires only that the MOVs don't start a fire when
> exposed to conditions which cause their break-down. They don't rate
> their ability to function as "surge protectors".
A Cuttler-Hammer tech note:
http://tinyurl.com/63594d
has some information on UL tests. Suppressors have to remain functional
through an initial set of surges (20 surges - 6kv, 3kA). They can fail
safely after that. (This sounds more like the service panel suppressor
test.)
--
bud--
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Author: bud--Date: 12:40 08-05-08
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Mike Tomlinson wrote:
> In article <76535$4821baa0$4213eb20$7766@DIALUPUSA.NET>, bud--
> <remove.budnews@isp.com> writes
>
>> Phone wires were clamped to ground before the 1960s?
>
> It was common to earth one leg of the incoming pair to either the house
> ground or to its own rod. An earth connection also allowed "party
> lines", where two houses could share one physical phone line pair, each
> house with its own number. Disadvantage was that both lines could not
> be used simultaneously.
>
> http://en.wikipedia.org/wiki/Party_line_(telephony)
>
> My previous house still had its telephone earth rod and earth wire,
> though it had not been connected to the phone line for many years.
>
I am pretty sure we had a party line long ago when I was a kid.
Wikipedia's reference to "20th century telephone systems" makes me feel
even older.
One side of the ringer is all that was connected to earth.
Not clamping phone wires to earth is a major surge suppression flaw. It
allows high voltage from phone to power wires (like at a modem), and
increases the stress on a multiport plug-in suppressor. A service panel
suppressor doesn't help the voltage difference at all.
Surprising since the UK seems to be very good on electrical protection
in general.
--
bud--
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On May 8, 10:52=A0am, bud-- <remove.budn...@isp.com> wrote:
>
> I would like to know the Joule ratings. The problem, as you say, is
> there is no standard way to measure the energy rating and some
> manufacturers apparently use questionable ratings. That has led some
> other reputable manufacturers, like SquareD, to not include Joule ratings.=
>
Here is a couple of nice article for evaluating SPD=92s.
Is the Joule rating of an SPD important?
While conceptually an surge protection device (SPD) with a larger
energy rating will be better, comparing SPD energy (Joule) ratings can
be misleading. More reputable manufactures no longer provide energy
ratings. The energy rating is the sum of surge current, surge
duration, and SPD clamping voltage.
In comparing two products, the lower rated device would be better if
this was as a result of a lower clamping voltage, while the large
energy device would be preferable if this was as a result of a larger
surge current being used. There is no clear standard for SPD energy
measurement, and manufacturers have been known to use long tail pulses
to provide larger results.
Additionally confusing this issue is the possibility that the rating
is just the energy absorbed, diverted, or the sum of both. NEMA LS 1
by specific omission does not recommend the comparison of SPD=92s energy
ratings. Comparison of single shot surge ratings and let-through
voltages is considered sufficient.
http://www.nemasurge.com/help.html
http://ecmweb.com/mag/electric_comparing_spd_performance/
http://www.control-concepts.com/pdfs/01_005.pdf
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf 2.5.1 Joule
Rating
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Author: EricDate: 14:25 08-05-08
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bud-- wrote:
> Mike Tomlinson wrote:
>> In article <76535$4821baa0$4213eb20$7766@DIALUPUSA.NET>, bud--
>> <remove.budnews@isp.com> writes
>>
>>> Phone wires were clamped to ground before the 1960s?
>>
>> It was common to earth one leg of the incoming pair to either the house
>> ground or to its own rod. An earth connection also allowed "party
>> lines", where two houses could share one physical phone line pair, each
>> house with its own number. Disadvantage was that both lines could not
>> be used simultaneously.
>>
>> http://en.wikipedia.org/wiki/Party_line_(telephony)
>>
>> My previous house still had its telephone earth rod and earth wire,
>> though it had not been connected to the phone line for many years.
>>
>
> I am pretty sure we had a party line long ago when I was a kid.
> Wikipedia's reference to "20th century telephone systems" makes me feel
> even older.
> One side of the ringer is all that was connected to earth.
>
> Not clamping phone wires to earth is a major surge suppression flaw. It
> allows high voltage from phone to power wires (like at a modem), and
> increases the stress on a multiport plug-in suppressor. A service panel
> suppressor doesn't help the voltage difference at all.
>
> Surprising since the UK seems to be very good on electrical protection
> in general.
>
I had a party line as a 10 year old. I used to screw with the other
party if I heard them when I picked up the phone.. strange noises, etc.
Of course I got caught, corporal punishment, etc.
I think they used to ring between the red green for one party, yellow
green for the other party, black green, etc.
Eric
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