Surge / Ground / Lightning

Mike Tomlinson wrote:
In article , Timothy Daniels
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--

In alt.tv.tech.hdtv en wrote:

| I'm curous to know how surge suppression can work without a ground
| (earth) of any sort. Does the "black box" detect overvoltage and
| disconnect the power like an earth leakage safety switch?

Without a ground of any sort, not all types of surges can be protected against.
But some can.

If the surge is a differential one (some use the term transverse), then what
the surge suppressor can do is cancel it out by effectively short circuiting
it to itself. A differential surge involves two wires with the voltage on
each being of opposite polarity and equal level. The MOV component inside
the suppressor will normally not be conductive. But when the voltage is high
enough, it becomes a conductor. The arrival of a high voltage differential
surge will result in the MOV between those 2 wires to become conductive.

If the surge is a common mode one, AND if the surge has a slow rise time,
then a device that is interconnected to other wires or other devices can
be protected by allowing the surge to pass to all devices at the same level.
As long as the rise is not too fast, keeping all the incoming wires, and all
the interconnected devices, at the same level results in insignificant current
flows. That surge will either reflect back from the protected equipment to
the suppressor, and from there go back through all the connected wires (which
could be more than where the surge arrived from).

Most strikes have lower energy levels at high frequencies than what would
cause damage. The exact frequency level that needs to be considered depends
on the internals of the equipment. For example, where it has inductance to
one end of a sensitive component like a CMOS chip, and no inductance to some
other end, this could result in a very brief fast rise of voltage high enough
to damage the CMOS chip. In some cases an LC circuit can actually increase
the voltage level of high frequency components (at the resonant frequency).
For example if you have energy at some voltage at 200 MHz, an LC series
circuit resonant at 200 MHz will result in a higher voltage being present
at the connection between the L and the C. So even in cases where there is
not enough energy at high frequency in a surge to cause direct damage, it
can still happen on some devices (think of them as having a lower threshold
of damage to simplify this).


| This might be fine for a TV, but surely not for a computer.

If everything the computer is connected to is protected at a common point
in the same surge suppressor, you can have this kind of protection, even
on a computer. That does mean if you have a phone line connected to a
modem, you need to protect both the phone line itself and the power to the
modem, in common with the computer.


| I don't recall any computer I've owned that did not have a three wire
| connection to the mains. That and a MOV is OK for smallish surges, but
| I believe that for a large surge, the sort that will blow a telephone
| off the wall, one needs a large, short-path earth for the surge
| detector to dump the extra power down.

Such a surge is likely to have high levels of high frequency energy. The
effective protection against these rare events is a combination of somewhere
to divert the energy (like a ground path), and something (like an inductor)
to ensure the energy does get diverted.

One problem is that at the point of use, an alternate ground path is not
practical. The grounding wire of the power circuit coule be as much a source
of the surge as the neutral wire would be. The place to put the diversion
system is at the entrance to the building. Most surges that come in by other
paths besides the entrance to the building are induced surges that will not
have so much energy and even less at high frequencies.

Still, I have seen three incidents in which an induced surge damaged a device
that was not connected to anything at all (in two cases they were battery
powered devices, and in the third, it was disconnected before the storm but
suffered damage anyway).


| I've got a few plug in protectors here and there to sop up a small
| spike, but when a storm is within a few km, I pull the phone wire out
| of the ADSL router, and the plug out of the mains. If I'm working at
| the time, I might just keep a watch on the weather radar and count
| lightning fashes to thunder times. It's rare that I get interrupted. I
| have underground power and phone lines so that gives a little extra
| protection, I believe. I've been told that Australian phone lines are
| the most vulnerable, and the most urgent to protect or disconnect.
| I hope to be going wireless soon which obviates this problem.

Disconnecting provides even better (but still not 100%) protection. Yes, the
underground wiring helps. I don't know the issues with Australian phone lines.
I do the wireless thing myself and feel much more comfortable with it. Most
of the past damaging surges I've seen come in do that on phone and cable wires,
and much less often on power wires. That may be due to the more sensitive
aspect of equipment where it connects to these wires.

--
|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) |

In alt.tv.tech.hdtv bud-- 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) |

In alt.engineering.electrical bud-- wrote:
| wrote:
| In alt.tv.tech.hdtv bud-- 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) |

wrote:
In alt.tv.tech.hdtv bud-- 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--

wrote:
In alt.tv.tech.hdtv bud-- 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--

Leonard Caillouet wrote:
"w_tom" wrote in message
...
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/St...004_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.....

In alt.engineering.electrical bud-- wrote:
| wrote:
| In alt.tv.tech.hdtv bud-- 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) |

bud-- wrote:

wrote:

In alt.tv.tech.hdtv bud-- 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.

In article ,
says...
bud-- wrote:

wrote:

In alt.tv.tech.hdtv bud-- 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