 |
Search Sci.Electronics.Basics |
|
|
|
|
|
|
 |
|
|
Sci.Electronics.Basics -> Surge / Ground / Lightning
There are 215 messages in this thread.
You are currently looking at messages 120 to 140.
|
Author: bud--Date: 14:40 05-05-08
|
|
Don Kelly wrote:
> ----------------------------
> "Tony Hwang" <dragon40@shaw.ca> wrote in message
> news:dncTj.112858$rd2.31639@pd7urf3no...
>> phil-news-nospam@ipal.net wrote:
>>> In alt.tv.tech.hdtv Michael A. Terrell <mike.terrell@earthlink.net>
>>> wrote:
>>>
>>> | Bullshit. Like ALL charges, it simply seeks a complete circuit to
>>> | flow. You have absolutely no grasp of the basic concepts, yet you
>>> | continue to spout your ignorance and lies.
>>>
>>> Not true.
>>>
>>> When you close a switch between a power source and a pair of wires that
>>> go
>>> out yonder, the electrical energy does not "know" whether the
circuit is
>>> complete or not. If it refused to flow, it would not be able to find
>>> out.
>>> It will flow, whether the circuit is complete or not. What happens after
>>> that depends on what is at the other end, which could be an open
>>> condition,
>>> a short circuit, or some kind of resistive or reactive load.
>>>
>>> You've claimed to have worked in broadcasting in an engineering role. So
>>> you should understand what happens at the end of an open transmission
>>> line.
>>> The electricity flows to get to the open end. Yet it is not a
"complete
>>> circuit".
>>>
>> Hmmm,
>> You seem to be confused between current flow(energy) and voltage(poential)
>> Nothing flows in an open circuit. If not we have to rewrite Ohm's law.
>> Show your credential to make a stamement like that.
>> Shameful.
> ------------------------
> Actually, you are showing some confusion. Phil is right in that he is
> bringing out a point that normal lumped RLC circuit theory doesn't handle
> because it essentially treats the speed of propagation of electrical signals
> as if it were infinite- which isn't true.
> .
> 2)Also, on energizing a line whether it is open or closed, there is a
> current flow as the applied voltage "sees" the characteristic impedance
of
> the line (wire or whatever) so a current will flow-even on an open circuit-
> until there is a modifying reflection from the termination. For a house the
> distances are such that this may be of the order of 0.1-0.2 microsecond.
> After all such reflections at terminations have ceased or are negligable,
> conventional circuit theory is applicable.
> In these situations, you are dealing with wave propagation rather than
> conventional circuit theory.
> This is the regime that is of interest in considering "surge protectors"
The last standards for simulating typical surge waveforms I have seen
(IEEE) were
1.2 us rise time, 50 us duration
8 us rise time, 20 us duration
a ring wave with a frequency about 100kHz.
All are long relative to 0.2 microsecond, so wave propagation should not
be relevant for household circuits.
A favorite article from w_ also uses a "8x20 us impulse as a very rough
representative pulse" with most harmonic content from 20kHz to 100kHz.
Martzloff, using the shorter rise time, has written: "For a 1.2/50 us
impulse, this means that the line must be at least 200 m long before one
can think in terms of classical transmission line behavior."
What reason is there to believe wave propagation is relevant to house
circuits?
>
> As to the advantage of "whole house" vs local surge protection,
"whole house
> protection depends on distances to all "protected" items being small.
Longer distances make the system more subject to effects like direct
induction from lightning into the wiring. I don't see why, in general,
the distance has to be small.
--
bud--
|
|
|
|
Author: Phil HowardDate: 14:55 05-05-08
|
|
In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
| Previously you said Martzloff "flubbed the experiment".
I remember that. You were telling me about some information he had
obtained from some experiment.
| Now you agree with Martzloff that branch circuit must be 200m for
| transmission line behavior with 1.2 microsecond rise time.
That's not a result of an experiment. I'm not so sure the exact distance
is 200m for that exact rise time. But that is a subjective thing. We are
likely not that far apart. It is a matter of degree to how different the
calculations come out when figuring them with transmission line issues and
ignoring those issues.
| You say that doesn't apply because surges are faster. Martzloff uses 1.2
| us because that is a standard rise time for surges produced by lightning
| as defined in IEEE standards.
Martzloff did not say that was a defined standard in the statement you
quoted. He just used it as an example to come up with the 200m figure.
Do you have some other statement from Martzloff or someone else about the
1.2 microsecond rise time?
| w_' professional engineer source says 8 micoseconds with most of the
| spectrum under 100kHz.
Even with 1 nanosecond rise time, most of the energy will be present in
the spectrum below 100 kHz. That means nothing when the surge is strong
enough to have energy above some frequency that is relevant to the whole
system involved that can do damage. That frequency might be 100 Mhz for
some thing, and 1 GHz for other things. Some surges, mostly from very
close direct strikes, can have damaging energy well above 1 GHz. It will
depend on how much inductance you have between the surge and the equipment
that needs to be protected. That's why I suggest that a good protection
scheme will include added inductance on the wiring at a level compatible
with the normal use (more can be added to power than to cable TV).
| You still have *no sources that support your belief* that risetimes are
| far faster.
I have experience and observation for that. I need no more.
| Again you did not read what I wrote (what a surprise):
| "I intended 'induced' meaning produced by including the most damaging -
| strikes to utility lines."
You are saying the most damaging strikes are induced? Or are you merely
adding the most damaging direct strikes in with the induced surges as a
set of surge classes that you want to consider together?
Your wording is so bad in that one sentence that I cannot tell what you mean.
It is vague and could satisfy more than one meaning.
--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
|
|
|
|
Author: bud--Date: 15:08 05-05-08
|
|
Mike Tomlinson wrote:
> In article <481f4eb2$0$31762$4c368faf@roadrunner.com>, Timothy Daniels
> <SpamBucket@NoSpamPlease.biz> writes
>
>> Does that mean a combination of w_tom's "whole house protection"
>> and individual "surge protectors" at those "critical
devices"? That's
>> what I've always felt would be prudent - not a single method of
>> protection, but a combination.
>
> Yes, but the environment in which the protected dwelling is situated
> should also be taken into account. For example, a house in Florida,
> with its overhead power lines and frequent thunderstorms, would be a
> more likely candidate for a combined approach to surge protection.
>
> On the other hand, installing Florida-levels of protection in a house in
> the UK with its infrequent storms, reliable underground power supply and
> a decent electrical system with properly earthed sockets, would be a
> waste of money.
>
Nice description. What you use depends on risk, and value of what you
are protecting.
The IEEE guide has, for max protection (not including lightning rods)
- adequate earthing
- short 'ground' wires from cable and phone entry protectors to the
'ground' at the power service (to limit the voltage between power and
signal wires)
- power service suppressor
- plug-in suppressor for high value "sensitive" electronics - especially
equipment with both power and signal connections (all wires to protected
equipment needs to go through the suppressor)
--
bud--
|
|
|
|
Author: Phil HowardDate: 15:45 05-05-08
|
|
In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
| The last standards for simulating typical surge waveforms I have seen
| (IEEE) were
| 1.2 us rise time, 50 us duration
| 8 us rise time, 20 us duration
| a ring wave with a frequency about 100kHz.
So now you are saying these figures represent a typical surge waveform,
as opposed to the worst case waveform you said a long time ago.
The term typical is generally accepted as a median. That means half of
the surges would have a slower rise time, and half would have a faster
rise time.
My concerns are not the typical surges. I suggest that half the surges
don't even need protection at all; they won't cause damage even if there
is no protection. But that also means half can be damaging and need the
protection. And a fraction of those surges need _substantial_ protection.
| All are long relative to 0.2 microsecond, so wave propagation should not
| be relevant for household circuits.
Maybe for the typical surge. How about for the most energetic 1% that are
the ones I'm most concerned with because they are hard to protect against.
| A favorite article from w_ also uses a "8x20 us impulse as a very rough
| representative pulse" with most harmonic content from 20kHz to 100kHz.
|
| Martzloff, using the shorter rise time, has written: "For a 1.2/50 us
| impulse, this means that the line must be at least 200 m long before one
| can think in terms of classical transmission line behavior."
And this statement is only using 1.2/50 us as an example. If you think
such a timing is the standard, why not offer a quote that actually says
that?
What does the "/" mean in that case, anyway? I never got to ask you that
before. Does it mean "divide 1.2 by 50"?
| What reason is there to believe wave propagation is relevant to house
| circuits?
The most damaging surges (not the typical ones) have substantial fast rise
high frequency energy (such as due to a very close direct contact strike).
In these cases, even if you can remove all of the low frequency energy, there
is still damaging energy in the higher frequencies that do follow transmission
line behaviour not only in wiring lengths of typical homes, but even in wiring
lengths inside a small appliance like a computer modem.
|> As to the advantage of "whole house" vs local surge protection,
"whole house
|> protection depends on distances to all "protected" items being small.
|
| Longer distances make the system more subject to effects like direct
| induction from lightning into the wiring. I don't see why, in general,
| the distance has to be small.
I believe he was referring to the distance between the whole house protection
and the ground/earth electrode.
For things like the service drop distance and the branch circuit distance, it
can be a tradeoff between different kinds of surges. The longer wiring will,
through its self-inductance, reduce the high frequency energy and slew the
rise time of the wavefront ... especially for common mode surges. However,
that same longer distance increases the potential level of induced surges
where the wire is effectively an antenna.
--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
|
|
|
|
Author: Phil HowardDate: 17:00 05-05-08
|
|
In alt.engineering.electrical bud-- <remove.budnews@isp.com> wrote:
| phil-news-nospam@ipal.net wrote:
|> In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
|>
|> | The last standards for simulating typical surge waveforms I have seen
|> | (IEEE) were
|> | 1.2 us rise time, 50 us duration
|> | 8 us rise time, 20 us duration
|> | a ring wave with a frequency about 100kHz.
|>
|> So now you are saying these figures represent a typical surge waveform,
|> as opposed to the worst case waveform you said a long time ago.
|
| Still missing - your source that indicates nanosecond rise times and
| 100MHz spectrum.
Observation.
|> What does the "/" mean in that case, anyway? I never got to ask you
that
|> before. Does it mean "divide 1.2 by 50"?
|
| It is standard notation in the surge field. 1.2 us risetime and 50 us
| duration
And what does the duration time have to do with high frequency energy?
Hint: nothing
--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
|
|
|
|
Author: bud--Date: 17:00 05-05-08
|
|
phil-news-nospam@ipal.net wrote:
> In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
>
> | Previously you said Martzloff "flubbed the experiment".
>
> I remember that. You were telling me about some information he had
> obtained from some experiment.
>
> | Now you agree with Martzloff that branch circuit must be 200m for
> | transmission line behavior with 1.2 microsecond rise time.
>
> That's not a result of an experiment.
"*From this first test*, we can draw the conclusion (predictable, but
too often not recognized in qualitative discussions of reflections in
wiring systems) that it is not appropriate to apply classical
transmission line concepts to wiring systems if ..."
As usual, you don’t know what was written.
> I'm not so sure the exact distance
> is 200m for that exact rise time. But that is a subjective thing.
Quit equivocating. Where is your cite. Like for nanosecond risetimes.
>
> | You say that doesn't apply because surges are faster. Martzloff uses 1.2
> | us because that is a standard rise time for surges produced by lightning
> | as defined in IEEE standards.
>
> Martzloff did not say that was a defined standard in the statement you
> quoted. He just used it as an example to come up with the 200m figure.
He used it because 1.2/50 (voltage) is an IEEE standard. The 8us from
w_’s engineer is another standard (8/20 current).
>
> | w_' professional engineer source says 8 micoseconds with most of the
> | spectrum under 100kHz.
>
> Even with 1 nanosecond rise time, most of the energy will be present in
> the spectrum below 100 kHz. That means nothing when the surge is strong
> enough to have energy above some frequency that is relevant to the whole
> system involved that can do damage. That frequency might be 100 Mhz for
> some thing, and 1 GHz for other things.
Still missing – your source. Nanosecond risetime. 100MHz spectrum.
>
> | You still have *no sources that support your belief* that risetimes are
> | far faster.
>
> I have experience and observation for that. I need no more.
Lots of people have experience and observation with flying saucers.
The rest of us want a source.
--
bud--
|
|
|
|
Author: bud--Date: 17:00 05-05-08
|
|
phil-news-nospam@ipal.net wrote:
> In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
>
> | The last standards for simulating typical surge waveforms I have seen
> | (IEEE) were
> | 1.2 us rise time, 50 us duration
> | 8 us rise time, 20 us duration
> | a ring wave with a frequency about 100kHz.
>
> So now you are saying these figures represent a typical surge waveform,
> as opposed to the worst case waveform you said a long time ago.
Still missing - your source that indicates nanosecond rise times and
100MHz spectrum.
>
> What does the "/" mean in that case, anyway? I never got to ask you that
> before. Does it mean "divide 1.2 by 50"?
It is standard notation in the surge field. 1.2 us risetime and 50 us
duration
--
bud--
|
|
|
|
Author: nobody >Date: 18:31 05-05-08
|
|
Leonard Caillouet wrote:
> "w_tom" <w_tom1@usa.net> wrote in message
> news:82da8b44-e386-4911-94c0-99b0671599ee@24g2000hsh.googlegroups.com...
>> People who are more than TV repairmen learn from their mistakes and
>> correct reasons for that failure. TV repairmen only fix defects -
>> never bother to learn how those failures can be avoided. Let's have
>> some fun. Let's reply using the same mockery and insult that Michael
>> uses. Except this post will be accurate about Michaels intelligence.
>
> I am merely a TV repairman who happens to have quite a bit of education,
> and has done much research on the matter. We began installing good
> basic MOV based suppression on our clients' systems long ago, using
> system level units that protect all incoming lines. We also pay close
> attention to proper grounding. What we have found over many years of
> this practice in one of the most lightning intense areas of the USA, is
> that our systems never take damage. During times of high thunderstorm
> activity, however, we see several times the repair volume, and
> invariably, the user did not use a surge suppressor. Our clients are
> happy with the systems that we sell and with the reliability. There are
> good reasons to suspect that system level surge suppressors do work, but
> grounding cannot be ignored.
>
> As for you w_tom, you have done far more to clutter groups than to
> provide any useful information. While your emphasis on grounding is
> good advice, much of the rest of your arguments are out of context and
> misleading. Michael may be a crochety ass sometimes, but at least he
> consistently provides useful information. Stick to preaching the
> importance of grounding and give the rest a break.
>
> Leonard
Thank you, Leonard, for a breath of fresh air in this onerous thread
that w_tom perpetuates ad infinitum. This isn't his first, for newbies
trying to fathom his morass.
I've been a TV repairman. I'm now a "communications electrician" which
means I deal with telephone lines/switches, land-mobile radio, microwave
radio systems, security systems, and the like; in high-voltage
switchyards and substations. We deal with huge surges from switching
transients and direct lightning hits on the transmission lines. I know
first-hand what happens when surges hit. When I said "transmission
lines", I'm talking both from the 60hz side as well as the RF side as
the lengths are sufficient to act that way.
Define "ground" or "earth", Mr w_tom. Have you ever run an ANSI spec
ohms test on one? I think not. I've done grounding for military tactical
radio systems and complete commo systems. What you think is "ground" may
not be ground at all due to soil composition. I've seen ground rod
"farms" made up of 20+ vertical 8' rods on a 10 foot grid come up in the
500 kilohms range when the same rods in the same location would test
lower than 1000 ohms if those same stakes were buried sideways 18" below
surface.
Substations/switchyards have "ground mats" of heavy copper wire in a
grid spacing of 1-2 feet and about 6 feet under everything that's
covered with gravel. It's also cad-welded at all intersections to
prevent corrosion. This ground mat system is also used at well-designed
radio sites. Even with this elaborate grounding system, a major
malfunction at 230KV can create such a voltage differential to induce
fatal "step voltage" between your legs.
http://ballengearry.com.au/papers/Step_and_Touch_Voltage_update_for_2004_090804.pdf
For 120Vac grounding on our equipment, we try our best to bring all
equipment grounds (racks and cable trays as well) to a single point that
*then* connects to the building's ground as close as possible. We do
have the advantage of most equipment running off DC at 24, 48, or 130
Vdc on huge battery racks that can absorb a lot of surge energy.....
|
|
|
|
Author: Phil HowardDate: 18:48 05-05-08
|
|
In alt.engineering.electrical bud-- <remove.budnews@isp.com> wrote:
| phil-news-nospam@ipal.net wrote:
|> In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
|>
|> | Previously you said Martzloff "flubbed the experiment".
|>
|> I remember that. You were telling me about some information he had
|> obtained from some experiment.
|>
|> | Now you agree with Martzloff that branch circuit must be 200m for
|> | transmission line behavior with 1.2 microsecond rise time.
|>
|> That's not a result of an experiment.
|
| "*From this first test*, we can draw the conclusion (predictable, but
| too often not recognized in qualitative discussions of reflections in
| wiring systems) that it is not appropriate to apply classical
| transmission line concepts to wiring systems if ..."
|
| As usual, you don?t know what was written.
What what kind of surge did Martzloff use to carry out that test?
|> I'm not so sure the exact distance
|> is 200m for that exact rise time. But that is a subjective thing.
|
| Quit equivocating. Where is your cite. Like for nanosecond risetimes.
Observation.
|> | You say that doesn't apply because surges are faster. Martzloff uses 1.2
|> | us because that is a standard rise time for surges produced by lightning
|> | as defined in IEEE standards.
|>
|> Martzloff did not say that was a defined standard in the statement you
|> quoted. He just used it as an example to come up with the 200m figure.
|
| He used it because 1.2/50 (voltage) is an IEEE standard. The 8us from
| w_?s engineer is another standard (8/20 current).
The standard for what? The typical surge?
|> | w_' professional engineer source says 8 micoseconds with most of the
|> | spectrum under 100kHz.
|>
|> Even with 1 nanosecond rise time, most of the energy will be present in
|> the spectrum below 100 kHz. That means nothing when the surge is strong
|> enough to have energy above some frequency that is relevant to the whole
|> system involved that can do damage. That frequency might be 100 Mhz for
|> some thing, and 1 GHz for other things.
|
| Still missing ? your source. Nanosecond risetime. 100MHz spectrum.
Observation. Of course this is a concept you cannot understand.
|> | You still have *no sources that support your belief* that risetimes are
|> | far faster.
|>
|> I have experience and observation for that. I need no more.
|
| Lots of people have experience and observation with flying saucers.
|
| The rest of us want a source.
The only flying saucers I have seen are the ones I've tossed.
--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
|
|
|
|
Author: BodenDate: 20:00 05-05-08
|
|
bud-- wrote:
> phil-news-nospam@ipal.net wrote:
>
>> In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
>>
>> | The last standards for simulating typical surge waveforms I have
>> seen | (IEEE) were
>> | 1.2 us rise time, 50 us duration
>> | 8 us rise time, 20 us duration
>> | a ring wave with a frequency about 100kHz.
>>
>> So now you are saying these figures represent a typical surge waveform,
>> as opposed to the worst case waveform you said a long time ago.
>
>
> Still missing - your source that indicates nanosecond rise times and
> 100MHz spectrum.
>
>>
>> What does the "/" mean in that case, anyway? I never got to ask you
that
>> before. Does it mean "divide 1.2 by 50"?
>
>
> It is standard notation in the surge field. 1.2 us risetime and 50 us
> duration
>
Sloppy notation.
|
|
|
|
Author: krwDate: 20:40 05-05-08
|
|
In article <fvo6qr11f4i@enews1.newsguy.com>, Boden@tidewater.net
says...
> bud-- wrote:
>
> > phil-news-nospam@ipal.net wrote:
> >
> >> In alt.tv.tech.hdtv bud-- <remove.budnews@isp.com> wrote:
> >>
> >> | The last standards for simulating typical surge waveforms I have
> >> seen | (IEEE) were
> >> | 1.2 us rise time, 50 us duration
> >> | 8 us rise time, 20 us duration
> >> | a ring wave with a frequency about 100kHz.
> >>
> >> So now you are saying these figures represent a typical surge waveform,
> >> as opposed to the worst case waveform you said a long time ago.
> >
> >
> > Still missing - your source that indicates nanosecond rise times and
> > 100MHz spectrum.
> >
> >>
> >> What does the "/" mean in that case, anyway? I never got to ask
you that
> >> before. Does it mean "divide 1.2 by 50"?
> >
> >
> > It is standard notation in the surge field. 1.2 us risetime and 50 us
> > duration
> >
> Sloppy notation.
s/sloppy/concise/
--
Keith
|
|
|
|
Author: Don KellyDate: 02:38 06-05-08
|
|
|
|
|
|
Author: w_tomDate: 02:47 06-05-08
|
|
Nobody described how much more earthing is installed in switching
centers (COs), electric substations, etc just to obtain a little
better earthing. A ten foot earth ground rod can be a massive
earthing improvement for surge protection. And then high reliability
facilities may spend $thousands more just to make that earthing but a
little better. Why so much extra conductors and labor for just a
little better ground? Because every little better earthing means that
much more surge protection. What makes a protector even more
effective? Better earthing.
So yes, where surge damage is not acceptable, then facilities will
do that much more work just to get a little better earthing. Earthing
is critical for direct lightning strikes without failure. Does that
mean a homeowner without a massive earthing mat should do nothing? Of
course not. Locating 3 meter ground rods (per post 1990 NEC
requirements) less than 10 feet from breaker box and telco provided
surge protector means significantly better protection. Anyone
building a new home should plan their surge protection where footings
are poured - see nobody's reference to cadwelding. Footings with
appropriately installed conductors (rebar) provide a home with
significant improvement (Ufer grounds). Protection should be planned
when the footings are poured. Better earthing (surge protection) for
so little money.
Nobody also discusses single point earth ground that is essential
for surge protection. Why? Again, a protector is only as effective
as its earth ground. Single point earth ground is essential to an
effective protector.
Some homeowners don't have that single point option due to failures
by the builder. One utility describes how to fix that defective
earthing:
http://www.cinergy.com/surge/ttip08.htm
Why do serious facilities do so much for their earthing system?
Earthing provides surge protection - where surge energy must be
harmlessly dissipated. And then, as Nobody notes, sometimes that
earthing system gets compromised by geology we did not know about.
What happens if damage occurs? We return to locate an earthing
defect. Even a nearby pipeline may adversely affect that earthing
system. If damage results, then discover a defect in the earthing
system. As Nobody demonstrates, so much labor to make earthing even
better because a surge protector is only as effective as that earth
ground.
BTW, battery racks do not absorb surge energy. Another concept even
taught in basic circuit theory - superposition. To surges, that
battery rack is equivalent to a short circuit. Batteries do not
absorb energy (if ignoring a battery's internal resistance). Those
batteries essentially connect surge currents to wires on both sides of
those batteries. To a surge, batteries are electrically equivalent to
a wire. Batteries are typically well earthed - meaning those
batteries will act just like a shunt mode surge protector - connecting
surge energy into earth. Batteries don't work as surge absorbers.
Batteries connect (shunt, divert, clamp) surge energy into earth.
On May 5, 6:31 pm, "nobody >" <usenetharves...@aol.com> wrote:
> I've been a TV repairman. I'm now a "communications electrician" which
> means I deal with telephone lines/switches, land-mobile radio, microwave
> radio systems, security systems, and the like; in high-voltage
> switchyards and substations. We deal with huge surges from switching
> transients and direct lightning hits on the transmission lines. I know
> first-hand what happens when surges hit. When I said "transmission
> lines", I'm talking both from the 60hz side as well as the RF side as
> the lengths are sufficient to act that way.
>
> Define "ground" or "earth", Mr w_tom. Have you ever run an ANSI
spec
> ohms test on one? I think not. I've done grounding for military tactical
> radio systems and complete commo systems. What you think is "ground" may
> not be ground at all due to soil composition. I've seen ground rod
> "farms" made up of 20+ vertical 8' rods on a 10 foot grid come up in the
> 500 kilohms range when the same rods in the same location would test
> lower than 1000 ohms if those same stakes were buried sideways 18" below
> surface.
>
> Substations/switchyards have "ground mats" of heavy copper wire in a
> grid spacing of 1-2 feet and about 6 feet under everything that's
> covered with gravel. It's also cad-welded at all intersections to
> prevent corrosion. This ground mat system is also used at well-designed
> radio sites. Even with this elaborate grounding system, a major
> malfunction at 230KV can create such a voltage differential to induce
> fatal "step voltage" between your legs.
>.http://ballengearry.com.au/papers/Step_and_Touch_Voltage_update_for_2...
>
> For 120Vac grounding on our equipment, we try our best to bring all
> equipment grounds (racks and cable trays as well) to a single point that
> *then* connects to the building's ground as close as possible. We do
> have the advantage of most equipment running off DC at 24, 48, or 130
> Vdc on huge battery racks that can absorb a lot of surge energy...
|
|
|
|
Author: w_tomDate: 02:53 06-05-08
|
|
On May 5, 2:35 pm, bud-- <remove.budn...@isp.com> wrote:
> The IEEE guide is aimed at "electricians, architects, technicians, and
> electrical engineers who were not protection specialists."
IEEE and NIST state fundamental facts. Industry standard facts and
embarrassing questions.that Bud will ignore to lie and to promote plug-
in protector sales:
1) How does that plug-in protector provide protection without the
'always necessary' earth ground? What does a protector do? Bud
provides only two citations. Both disagree with his claims. The NIST
bluntly defines what a protector must do - Page 6:
> You cannot really suppress a surge altogether, nor
> "arrest" it. What these protective devices do is
> neither suppress nor arrest a surge, but simply
> divert it to ground, where it can do no harm.
Bud says his plug-in protectors somehow suppress or arrest surges.
Somehow, 'clamping to nothing' means that surge energy disappears?
Somehow protectors can work without earthing? NIST citation further
contradicts Bud on Page 17:
> 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.
2) Bud not only denies this also so important single point earth
ground. He also ignores what happens when a protector is too far from
earth and too close to appliances. Page 42 Figure 8: the surge
earthed 8000 volts destructively through appliances. This is the
second point from his citations that Bud must ignore.
3) So if a plug-in protector is effective protection, then
manufacturer specs will list each type of surge and protection from
that surge. Bud never provides that spec either. Why? Plug-in
protectors don't claim to protect from the type of surge that
typically causes damage. Not one plug-in protector manufacturer will
claim that protection - made obvious because Bud will not post those
specs and ignored over 400 requests for those specs.
4) No earth ground means no effective protection. A protector is
only as effective as its earth ground. Another reality that Bud must
ignore to post incessantly.
None of this is new. It is again posted because Bud continuously
ignores that even his own citations contradict him. Meanwhile w_tom
has provided many tens of professional citations that also contradict
Bud; that define how effective protection is routinely installed where
direct lightning strikes must not cause damage. We install effective
protection for lightning so that all other (and lesser) surges are
also made irrelevant. Surge protection is so routine for the past 100
years as to be traceable to human failure. Even the protector must
remain functional after a surge.
|
|
|
|
Author: w_tomDate: 03:06 06-05-08
|
|
On May 5, 2:27 pm, Mike Tomlinson <m...@jasper.org.uk> wrote:
> It is those nuances that w_twat fails to explain when he spouts his one-
> cure-for-all-ills religious mantra about every dwelling absolutely
> requiring whole-house surge protection.
Mike Tomlinson has just posted in agreement. UK homes typically do
not need what is necessary in FL homes. UK homes need not be earthed
as central FL homes may be earthed:
http://members.aol.com/gfretwell/ufer.jpg
Many homes have more than enough protection with only one earthed
'whole house' protector - and nothing else. Especially in the UK.
That means spending tens (or maybe one hundred) times less money for
protection of everything.
UK homes may be more than sufficiently earthed with one 3 meter
ground rod. Then one surge protector can provide more than sufficient
protection for everything - eliminating maybe =A3500 or =A32000 for plug-
in protectors.
|
|
|
|
Author: w_tomDate: 03:13 06-05-08
|
|
On May 4, 9:09 pm, "Michael A. Terrell" <mike.terr...@earthlink.net>
wrote:
> The same thing we did in the studios and transmitter sites. Use a
> combination of protection at the building's main disconnect, and
> individual protection at each critical device. The only thing that I've
> lost in the last ten years was when lightning hit a huge pine tree, and
> cut the top half of it off. It landed on the ground right over the
> buried telephone line, and a second strike blew out the modem and MOV
> protection on the phone line.
You suffered damage from a lightning strike and call that effective
protection? Modems are most typically damaged by surges entering an
AC mains. Outgoing surge path would be the phone line to earth via a
telco installed 'whole house' protector. Damage from lightning is
effective protection? After spending how much for all those
protectors, you call that protection?
Phone lines do not use MOV protectors. Basic information that you
would have learned if not wasting time insulting people. MOVs have
too much capacitance. Phone line 'whole house' protectors use other
technologies with lower capacitance.
|
|
|
|
Author: Phil HowardDate: 03:29 06-05-08
|
|
In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:
| Now - is this all germane to household protection? You say not and I agree
| with you- because household equipment can ride through - at worst- doubling
| of the clamped voltage for a very short time even though the clamped voltage
| is relatively small compared to the peak of the incoming surge. --
What if the surge is an extreme case (e.g. direct strike very near) and it is
arriving at protection devices in common mode (same polarity on all three
wires). Bud's assertion _seems_ to be that no surge could ever be of the
type with substantial energy at high frequencies. My belief is that they
can, and will at times. Lightning strokes have that energy, or else you
would not receive them on UHF. If the stroke is strong _and_ close (e.g.
less line inductance between the point of strike and where it is being
considered), then more of that UHF energy will arrive.
I have seen damage patterns in electronics that strongly suggests that there
were specific paths involved based on minor levels of reactance in the circuit.
A resistor would be melted along one path, but not so along another which had
a small inductor (3 turns in air) in the way. And this device (a VCR) was on
a surge protector along with a TV that was unharmed.
If Bud is just arguing about the _typical_ (median?) surge level, then maybe
we are arguing apples and oranges. I certainly don't intent to protect against
50% of surges. My target is better than 99%. I want to feel comfortable
sleeping through a severe thunderstorm while my computers and media center
remain plugged in.
I do agree that things can survive at the clamping voltage. But there has to
be a clamping situation. It's too easy for a surge to come in as a common
mode surge where the voltage difference across the MOVs would be (nearly) zero.
Then all we have is a propogating wavefront. And if it is strong and/or close
then we have very fast rise times. And it passes by the MOVs "laterally".
There's probably a big difference of opinion about just how much protection is
worth it. But one thing I do see in at least part of this thread is that Bud
focuses on quoting things other people say, and does very little to express
things in his own words. That suggests he reads but does not fully understand.
And that means I can't ask questions of what is said in the thread. Since Bud
can't (or won't) defend what he's saying in his own words based on his own
knowledge, it's not really a two way street. His "experts" are not involved
in the debate; they can neither defend their position nor be questioned about
it to get more details.
It also has brought some other comments from people who are either anti-social
insulting types, or those that just don't understand what is said (apparently
having never dealt with transmission line propogation), or both. But at least
I know who not to trust any technical opinions from when I have question to
ask about things I want to learn more about.
--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
|
|
|
|
Author: Mike TomlinsonDate: 06:01 06-05-08
|
|
In article <d75666d1-5cc7-4955-ac34-b666e67e9ced@24g2000hsh.googlegroups
.com>, w_tom <w_tom1@usa.net> writes
> Mike Tomlinson has just posted in agreement.
As usual, you're twisting things again. I'm certainly not agreeing with
_you_.
> UK homes typically do
>not need what is necessary in FL homes.
instead, YOU are agreeing with what I said...
> UK homes need not be earthed
>as central FL homes may be earthed:
> http://members.aol.com/gfretwell/ufer.jpg
Those pictures do absolutely nothing to bolster your argument,
especially appearing as they do without any explanatory text.
> Many homes have more than enough protection with only one earthed
>'whole house' protector - and nothing else. Especially in the UK.
Nonsense. You live in Pennsylvania (thankfully, though I do feel sorry
for your neighbours and anyone else with whom you come into contact.)
It is not common practice to install whole-house protectors in the UK.
> UK homes may be more than sufficiently earthed with one 3 meter
>ground rod.
You have no idea. TT earthing (ground rod earthing) is relatively
unusual in the UK. The majority of buildings have a T-N-C-S supply from
the utility provider, who provide an earth point alongside the supply
cable where it rises out of the ground.
> Then one surge protector can provide more than sufficient
>protection for everything - eliminating maybe £500 or £2000 for plug-
>in protectors.
Absolute crap. You have no idea how much surge protectors in the UK
cost.
w_ once again lies, distorts, and twists what others say to suit his own
bizarre beliefs and ideologies.
w_ continues to lead his one-man crusade and is unable to understand why
his dogmatic posts attract contempt and derision from many different
people with a wide spectrum of experience and knowledge of electrical
and electronic theory and practice.
w_ continues to believe that he alone is Right and everyone else is
Wrong, a classic sign of a sociopathic personality. w_twat needs to
consult a mental health professional.
--
(\__/) Bunny says NO to Windows Vista!
(='.'=) http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.html
(")_(") http://www.cypherpunks.to/~peter/vista.pdf
|
|
|
|
Author: EricDate: 10:22 06-05-08
|
|
phil-news-nospam@ipal.net wrote:
> In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:
>
> | Now - is this all germane to household protection? You say not and I agree
> | with you- because household equipment can ride through - at worst- doubling
> | of the clamped voltage for a very short time even though the clamped voltage
> | is relatively small compared to the peak of the incoming surge. --
>
> What if the surge is an extreme case (e.g. direct strike very near) and it is
> arriving at protection devices in common mode (same polarity on all three
> wires). Bud's assertion _seems_ to be that no surge could ever be of the
> type with substantial energy at high frequencies. My belief is that they
> can, and will at times. Lightning strokes have that energy, or else you
> would not receive them on UHF. If the stroke is strong _and_ close (e.g.
> less line inductance between the point of strike and where it is being
> considered), then more of that UHF energy will arrive.
>
> I have seen damage patterns in electronics that strongly suggests that there
> were specific paths involved based on minor levels of reactance in the circuit.
> A resistor would be melted along one path, but not so along another which had
> a small inductor (3 turns in air) in the way. And this device (a VCR) was on
> a surge protector along with a TV that was unharmed.
>
> If Bud is just arguing about the _typical_ (median?) surge level, then maybe
> we are arguing apples and oranges. I certainly don't intent to protect against
> 50% of surges. My target is better than 99%. I want to feel comfortable
> sleeping through a severe thunderstorm while my computers and media center
> remain plugged in.
>
> I do agree that things can survive at the clamping voltage. But there has to
> be a clamping situation. It's too easy for a surge to come in as a common
> mode surge where the voltage difference across the MOVs would be (nearly) zero.
> Then all we have is a propogating wavefront. And if it is strong and/or close
> then we have very fast rise times. And it passes by the MOVs
"laterally".
>
> There's probably a big difference of opinion about just how much protection is
> worth it. But one thing I do see in at least part of this thread is that Bud
> focuses on quoting things other people say, and does very little to express
> things in his own words. That suggests he reads but does not fully understand.
> And that means I can't ask questions of what is said in the thread. Since Bud
> can't (or won't) defend what he's saying in his own words based on his own
> knowledge, it's not really a two way street. His "experts" are not
involved
> in the debate; they can neither defend their position nor be questioned about
> it to get more details.
>
> It also has brought some other comments from people who are either anti-social
> insulting types, or those that just don't understand what is said (apparently
> having never dealt with transmission line propogation), or both. But at least
> I know who not to trust any technical opinions from when I have question to
> ask about things I want to learn more about.
>
I can attest to vhf/uhf content in lightning strikes. I worked for a
communications outfit. We owned and maintained a number of comm sites
with towers and antennas. One strike on an antenna destroyed the LDF rf
cable all the way to the polyphaser at the bottom of the tower. It had
blowouts at about 1 foot intervals all down it's length suggesting a
1/2 wave of about 1 foot or approx 460 mhz. That's one hell of a lot of
energy at that frequency..
Eric
|
|
|
|
Author: Tzortzakakis DimitriosDate: 11:39 06-05-08
|
|
? <spamfree@spam.heaven> ?????? ??? ??????
news:hkfu149a5vrit5hmv0diutsv7daiqor67i@4ax.com...
> On Mon, 5 May 2008 19:21:16 +0300, "Tzortzakakis Dimitrios"
> <noone@nospam.void> 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'm on 2000' of sand, and at the moment, my house earth is the copper
>
2000'? I am only 5'10":-)
>water pipes, but the water corp keep adding plastic bits here and
> there, so I don't really trust it. I was going to hammer in a 20'
> length of 3/4" copper pipe under a large tree which gets the drain
> from my grey water. Probably the best I can do.
>
Perhaps you should get a proper earthing electrode, with a spiked end and a
stell core? It would be really difficult to hammer 20' of 3/4" copper pipe.
They are not that expensive.
> I'm not a full bottle on earth loops yet so i don't know about leaving
> the water mains connection still connected.
The earth loops matter only in electronic circuits, like amplifiers and the
like. In electricity, the play no role, in fact they reduce even further the
earth resintance.
> What's the best way to test an earth?
> I heard once that a large electric radiator (fire) connected between
> active (hot) and the earth will glow as per normal if the earth has
> good capacity. Perhaps a current comparison between the earth return
> and neutral return would be more informative?
>
Although the neutral is at zero potential, still carries a large current.
The earth not. Since the neutral point of the LV side of the local
substation is earthed, for the electricity "is all the same" between neutral
and earth, depending on the neutral earthing system.
>
--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
|
|
|
|
|
|
|
|
|
Contact | Electronic Portal
|
|
|
