Surge / Ground / Lightning

Don Kelly wrote:
----------------------------
"bud--" wrote in message
.. .
Don Kelly wrote:
----------------------------
"Tony Hwang" wrote in message
news:[email protected]
wrote:
In alt.tv.tech.hdtv Michael A. Terrell
wrote:

| Bull****. 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.
----------------------------------------
Your point is true- the time interval is so small that for practical
purposes it can be ignored. I am not denying that. Obviously I gave that
impression- sorry for that.

I was simply pointing out that phil had it right in theory and Tony had it
wrong.

After this time for the wave to travel to the end and be reflected (and
other re-reflections die out) then conventional circuit theory is
applicable. The fact that the time is extremely small simply means that we
can pretend that it doesn't even exist.

While Matzloff is right in the time for a round trip is of the order of
200m, it is also dangerous to assume that one can ignore waves for shorter
distances. For example, a stroke to a tower of an EHV line (a lot less than
200m) will go down the tower, meet ground resistance and be reflected.
Such reflections have been found to be more likely to cause flashover than
direct strokes to the line (EPRI). Similarly, the practice in substations
is not "whole station" protection (where this is applicable, it must be done
considering a number of factors- quite interesting ) and putting specific
protection as near as possible to the protected apparatus-definitely within,
say, 10m. - It's not just the time to peak that is the critical factor. Do a
lattice diagram approach or use Bergeron's method (Hermann Dommel did a lot
of work with this at EPRI and has a lot of papers in IEEE- more dealing with
switching surges than lightning).
It's been a long time since I did any calculations in this area so I would
have to brush up.

I am real glad the probability of a direct house strike is low. I have
some appreciation for the earthing/bonding required in a substation
(also referred to by nobody).


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. --

The effect Martzloff was specifically looking for in experiments was
doubling of voltage.

As an aside, several of the experiments done by Martzloff were at EPRI.

--
bud--

In alt.engineering.electrical bud-- wrote:
| wrote:
| In alt.engineering.electrical bud-- wrote:
| | wrote:
| | In alt.tv.tech.hdtv bud-- wrote:
|
| | | 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.
|
| Observation proves flying saucers and magic.
|
| Without supporting sources it is Phil's Phantasy Physics.
| Where is a source that supports your belief in nanosecond risetimes and
| 100MHz spectrum?

Since you seem unwilling to just discuss technical aspects of things, I have
to conclude that you simply do not understand what it is you read and quote.
Too many times you quote out of context. I don't know where that is because
you are trying to be manipulative or simply on account of ignorance. There
is that old sayind "Do not ascribe to malice that which can be explained by
ignorance". I don't know if I should follow it's advice.

There is no point in spending the effort to find some quotable source because
you wouldn't know what to do with it. How could you possibly comprehend what
I would give you if you can't even comprehend what you post.

After this round of followups, I'm done with this thread and I'm done replying
to you. If curing your ignorance is in your future, it will have to be from
someone else.

--
|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 Eric wrote:

| 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..

Apparently you had some kind of resonance involved. Maybe the antenna itself
can cause that. Or the output tank circuit in the transmitter. Once you have
the resonance to narrowband the energy, it would only take a reflection back
up the line and you turn a propogating surge into standing waves.

--
|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) |

w_tom wrote:

But when a plug-in protector is sold to maximize
profits (not for protection), then grossly undersized protectors also
create another problem - scary pictures:
http://www.hanford.gov/rl/?page=556&parent=554

w_ can't understand his own hanford link. It is about "some older
model" power strips and says overheating was fixed with a revision to
UL1449 that required thermal disconnects. That was 1998. There is no
reason to believe, from any of these links, that there is a problem with
suppressors produced under the UL standard that has been in effect since
1998.
But with no valid technical arguments all w_ has is pathetic scare tactics.

For reliable information on surges and protection read the IEEE and NIST
guides. (Both say plug-in suppressors are effective.)

--
bud--

In alt.engineering.electrical bud-- wrote:
| wrote:
| In alt.engineering.electrical Don Kelly 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. --
|
| My belief is that they
| can, and will at times.
|
| People believe in flying saucers.
| Where is a source that supports your belief?

My observations support my belief. I don't expect YOU to believe it on the
basis if MY observations, as I certainly won't believe things on the basis
of YOUR observations. What I am posting about is for you to UNDERSTAND what
I believe, not that you have to believe it. Maybe someday you will come to
understand it, and then you might realize how you have misread what it is
you have been quoting online.

Since you spend all your keystrokes making person attacks or insisting on
something being cited, or make quotes that are often truncated incorrectly
or misapplied, I can only conclude you have no actual understanding of what
it is you have been quoting. What good would me citing anything do for you
if you can't understand it.


| 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".
|
| Where is a source that supports your belief in nanosecond risetimes and
| 100MHz spectrum?

Another poster followed up to my post you just followed up to that also has
experienced the same thing. That might not be some published citation that
you want. But that doesn't matter. It seems you can't comprehend what this
is about regardless of whether it is observed by others, or yourself, or by
the experts you cite.


| 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.
|
| I focus on the real world. You focus on your beliefs.

You focus on citing and quoting things you do not understand well enough to
just talking about them in technical terms.


| Where is a source that supports your belief in nanosecond risetimes and
| 100MHz spectrum?

See above.

And after this round of followups, I'm done with this thread and with your
posts on this subject. You can have the last say, but I will not even read
it.

--
|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) |

On May 5, 2:20*pm, wrote:
In alt.engineering.electrical wrote:

| On May 5, 1:44?am, wrote:
| In alt.tv.tech.hdtv bud-- wrote:| wrote:
|
| | In alt.engineering.electrical Leonard Caillouet wrote:| | wrote in message
|
| | ...
| | | In alt.tv.tech.hdtv Franc Zabkar wrote:
| | |
| | |
| | | The MOVs will act like conductors when they are clamping. ?The surge will
| | | take both paths ... the path through the MOVs, and the path going past the
| | | MOVs. ?In general, about 50% will go each way. ?That can vary at higher
| | | frequencies.
| | |
| | | Why would you assume that 50% will go each way when you don't know the
| | | impedance of each direction? ?When conducting, or at failure, the MOV has a
| | | very low impedance.
| |
| | There is a distinction between "go each way" and "what comes back" due to
| | the impedance. ?It will be about 50% that goes each way _because_ the power
| | itself does not (yet) know the impedance (at a distance), until it gets
| | there.
| |
| | Another installment of Phil's Phantasy Physics using transmission line
| | theory.
|
| Not understanding it is your loss.
|
|
| I have to agree that this is Phantasy Physics. * *We're supposed to
| believe that a surge reaching a MOV is going to split 50-50, with half
| of it going to the MOV path and half moving on down the line,
| reagrdless of the impedance of the two paths? * *That would render all
| surge protection about 50% effective.

You did not read very carefully. *The reference to 50-50 split is about the
contribution of the MOVs themselves. *That is an essential understanding of
the components so the whole system can be figured out. *The impedance down
the paths is another separate component, which also has to be figured in
when determining the whole picture.

You have confused a component with the entire system. *You need to read more
carefully. *Or you need to understand the distinction of individual components
as they apply to the whole system

The whole wiring system is extrememly complex. *It cannot be understood
properly without first understanding the components. *And that includes
understanding that MOVs, when they conduct, do look to the propogating
energy as two paths to go down, and it will (initially) go both ways in
about an equal amount.

Maybe you should review what you actually stated in the context of
current surge supression discussion:
"
"The MOVs will act like conductors when they are clamping. The surge
will
| | take both paths ... the path through the MOVs, and the path
going past the
| | MOVs. In general, about 50% will go each way. That can vary at
higher
| | frequencies. "

That sure sounds like 50% of the surge is going through the MOV and
the other 50% is going on past it to the protected equipment.

And that I would have to agree with Bud on, it's phantasy physics,
because if it were true, no type of surge protection would work,
because it would only be 50% effective.




--
|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.engineering.electrical Eric wrote:

| 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..

Apparently you had some kind of resonance involved. Maybe the antenna itself
can cause that. Or the output tank circuit in the transmitter. Once you have
the resonance to narrowband the energy, it would only take a reflection back
up the line and you turn a propogating surge into standing waves.

Pretty much what we determined. Also in another thread I stressed that
the rise time by itself does not determine frequency content. One needs
to know the rate of change, or slew rate, to determine that. A
lightning pulse may have a rise time of 1.2 microseconds but in that
short time the current can rise to thousands of amps, generating a large
amount of vhf,uhf energy.
Eric

Tzortzakakis Dimitrios wrote:
Ï "Tantalust" Ýãñáøå óôï ìÞíõìá
. ..
"NB" wrote in message
...
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


Can you trim W_tom with that?? Or is he incurable?

On May 6, 12:08*pm, "Michael A. Terrell"
wrote:
w_tom wrote:

On May 4, 9:09 pm, "Michael A. Terrell"
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?

* *Where did I say HOW was protected? It was my second week at that
station, and the chief engineer took off on a long overdue vacation. If
you would learn to read, rather than just do mindless rants you wouldn't
look so stupid. *At that time the building had a UFER ground, and a
three phase protection system at the meter CTs. That didn't prevent the
damage, as you claim it should.

* Phone lines do not use MOV protectors. *Basic information that you
would have learned if not wasting time insulting people.

* *Sorry, _wacko_ but you are the one slinging insults and ignoring
proof from hundreds of people.

*MOVs have
too much capacitance. *Phone line 'whole house' protectors use other
technologies with lower capacitance.

* *Gee, _wacko_ you've never seen ANY modern business telephone
equipment? *Gas tubes are fragile and very expensive. The protection
isn't to save the privately owned telephones, it it to limit damage to
the building. *Even that mid '60s 1A2 system had every output of the
power supply fused to prevent a fire. Explain why an MOV's capacitance
is high enough to affect a phone line. Never mind. *I have a Nitsuko/NEC
DX2NA-32SYTEMEM KEY TELEPHONE SYSTEM in front of me, and every CO line
in it has a MOV across the line. *Once more, you're preaching lies and
using deceit to try to make others look bad.

,http://refurbishednitsuko.net/productInfo.aspx?productID=75978489-9ac....
is the Central Office line card for four telephone lines. See the black
MOVs to the right of each pair of fuses?

http://refurbishednitsuko.net/productInfo.aspx?productID=f5453e33-047....
is the card for four standard 2500 type telephones, or equivalent
equipment. See the pairs of black MOVs over the blue connectors at the
bottom of the screen? They are all japanese, with no brand markings.

http://www.epcos.com/web/generator/Web/Sections/Publications/PDF/SIOV...
is the Epcos MOV databook, with datasheets for Telecom applications.
page 213 list the TELECOM MOV data.

* *Every line into that studio building had a long distance call device
diverter in the line that had MOV across the phone line. Every one of
them survived the direct hit to the building and STL tower. That's more
than can be said of your ability to use reason, and learn new things.

* *You need to get your head out of 1920 and learn modern electronics.
The one thing we learned today is that you don't know any more about
Telecom that you do lightning protection, or reading comprehension.


W_ denies MOVs are commonly used in typical electonics or modern
appliances too. He had to, because he can't answer the obvious
question of how MOVs can be used effectively in these applications,
yet they can't work in plug-in protectors and the only way to get any
protection is to have a nearby direct earth ground. Faced with the
problem of MOVs providing protection in electronics/appliance without
an earthground, he simply denies MOVs are used in electronics and
appliances. Here's the references that I provvided him on that one:

Here, from Appliance Magazine and Appliance Design websites:

http://www.appliancedesign.com/CDA/A.../BNP_GUID_9-5-...


"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.


These devices help provide protection in a wide range of AC line
applications, including AC mains LED lighting systems, PLC network
adapters, cell-phone chargers, AC/DC power supplies (up to 30 VA as
input power for 230 VAC input voltage), modem power supplies, AC
panel
protection modules, AC power meters, and home appliances. "


http://www.appliancemagazine.com/pri...zone=1&first=1


"Protecting increasingly sophisticated and complex control boards
from
misconnection, power surges, or short circuit damage is of particular
concern to the equipment manufacturer. Although appliance
transformers, their enclosures, and connections are capable of
withstanding higher voltage transients, the use of sensitive solid-
state devices on the board necessitates improved overcurrent,
overtemperature, and overvoltage control.


Coordinating overcurrent and overvoltage protection can also help
designers comply with safety agency requirements, minimize component
count, and improve equipment reliability. A metal oxide varistor
(MOV)
overvoltage protection device used in a coordinated circuit-
protection
strategy with a line-voltage-rated PPTC overcurrent device helps
manufacturers meet IEC 6100-4-5, the global standard for voltage and
current test conditions for equipment connected to ac mains."

In article , bud--
writes

Martzloff has written "the impedance of the grounding
system to 'true earth' is far less important than the integrity of the
bonding of the various parts of the grounding system."

Indeed. This is an important principle of the UK wiring code. It's
referred to as "equipotential bonding." Such a concept, of course,
would be far beyond the understanding of w_'s lone brain cell.

--
(\__/) Bunny says NO to Windows Vista!
(='.'=) http://www.cs.auckland.ac.nz/~pgut00...ista_cost.html
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