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nuclear EMP protection???

R

Robert Morein

Jan 1, 1970
0
I want to implement a degree of protection from nuclear-induced EMP for my
home electronics, principally my computer network.

Although severe EMP effects require a Faraday shield, I'm aiming for a
modest amount of protection, ie., all I can do at modest cost, that might
improve survivability near the fringe of the effect area. So I'm switching
to optical fiber for the network connections, and putting isolation
transformers in front of the UPS'es.

I can't find details for the kind of powerline surges that are caused by
nuclear induced EMP. Is it a ringwave, or a DC pulse? How strong, how long?
Common and/or normal mode?

Comments/info appreciated.
 
J

John Larkin

Jan 1, 1970
0
I want to implement a degree of protection from nuclear-induced EMP for my
home electronics, principally my computer network.

Although severe EMP effects require a Faraday shield, I'm aiming for a
modest amount of protection, ie., all I can do at modest cost, that might
improve survivability near the fringe of the effect area. So I'm switching
to optical fiber for the network connections, and putting isolation
transformers in front of the UPS'es.

I can't find details for the kind of powerline surges that are caused by
nuclear induced EMP. Is it a ringwave, or a DC pulse? How strong, how long?
Common and/or normal mode?

Comments/info appreciated.

By the time there's enough EMP to zap your gear, you're probably dead
anyhow.

Why worry about this?


John
 
D

Don Pearce

Jan 1, 1970
0
I want to implement a degree of protection from nuclear-induced EMP for my
home electronics, principally my computer network.

Although severe EMP effects require a Faraday shield, I'm aiming for a
modest amount of protection, ie., all I can do at modest cost, that might
improve survivability near the fringe of the effect area. So I'm switching
to optical fiber for the network connections, and putting isolation
transformers in front of the UPS'es.

I can't find details for the kind of powerline surges that are caused by
nuclear induced EMP. Is it a ringwave, or a DC pulse? How strong, how long?
Common and/or normal mode?

Comments/info appreciated.

You need to get out more.

d
Pearce Consulting
http://www.pearce.uk.com
 
D

Dave Holford

Jan 1, 1970
0
Robert said:
I want to implement a degree of protection from nuclear-induced EMP for my
home electronics, principally my computer network.

Although severe EMP effects require a Faraday shield, I'm aiming for a
modest amount of protection, ie., all I can do at modest cost, that might
improve survivability near the fringe of the effect area. So I'm switching
to optical fiber for the network connections, and putting isolation
transformers in front of the UPS'es.

I can't find details for the kind of powerline surges that are caused by
nuclear induced EMP. Is it a ringwave, or a DC pulse? How strong, how long?
Common and/or normal mode?

Comments/info appreciated.


I would think that if an EMP pulse was severe enough to damage your
equipment you should anticipate possible loss of the commerical power
network in your area. So maybe you would be better off concentrating on
a completely self-contained system?

I have worked with EMP protected systems, all of which have had their
own dedicated backup generators with at least a 7 day fuel supply.

Dave
 
J

Jim Yanik

Jan 1, 1970
0
I want to implement a degree of protection from nuclear-induced EMP
for my home electronics, principally my computer network.

Although severe EMP effects require a Faraday shield, I'm aiming for a
modest amount of protection, ie., all I can do at modest cost, that
might improve survivability near the fringe of the effect area. So I'm
switching to optical fiber for the network connections, and putting
isolation transformers in front of the UPS'es.

I can't find details for the kind of powerline surges that are caused
by nuclear induced EMP. Is it a ringwave, or a DC pulse? How strong,
how long? Common and/or normal mode?

Comments/info appreciated.

What makes you think there's going to be -any- nuclear detonations in your
vicinity?

Live in/near NYC or Washington,DC?

If there IS a nucdet,your home electronics are going to be the least of
your worries.
 
R

Robert Morein

Jan 1, 1970
0
Jim Yanik said:
What makes you think there's going to be -any- nuclear detonations in your
vicinity?

Live in/near NYC or Washington,DC?

If there IS a nucdet,your home electronics are going to be the least of
your worries.
I live near Philadelphia.
An airburst 100 miles away -- NYC, Baltimore, or Washington, would have no
effect on me unless were unlucky enough to see the flash.
However, it would damage a tremendous amount of infrastructure, and cause
EMP.
You are correct that there would be other, serious problems. However,
assuming the power grid came back up in a week or so, it would be nice to
have the infrastructure of my existence in working condition.
 
H

Hank

Jan 1, 1970
0
I bet the odds are much better for a smallish (500m to 2km) asteroid to cause
damage to your infrastructure.

I wonder what the odds would be for meteor impact vs terrorist nuclear bomb?
 
A

Activ8

Jan 1, 1970
0
I live near Philadelphia.
An airburst 100 miles away -- NYC, Baltimore, or Washington, would have no
effect on me unless were unlucky enough to see the flash.
However, it would damage a tremendous amount of infrastructure, and cause
EMP.
You are correct that there would be other, serious problems. However,
assuming the power grid came back up in a week or so, it would be nice to
have the infrastructure of my existence in working condition.

All I had to do was google EMP and I got more than enough info
 
G

Gregory L. Hansen

Jan 1, 1970
0
I want to implement a degree of protection from nuclear-induced EMP for my
home electronics, principally my computer network.

Although severe EMP effects require a Faraday shield, I'm aiming for a
modest amount of protection, ie., all I can do at modest cost, that might
improve survivability near the fringe of the effect area. So I'm switching
to optical fiber for the network connections, and putting isolation
transformers in front of the UPS'es.

I can't find details for the kind of powerline surges that are caused by
nuclear induced EMP. Is it a ringwave, or a DC pulse? How strong, how long?
Common and/or normal mode?

Comments/info appreciated.



As I understand it, the EMP comes from the gamma flash stripping electrons
from atmospheric molecules, and they can bounce around for many minutes
before settling down.

Hardening equipment against nuclear EMPs is sort of a specialized topic, I
don't know much about it. But you should really design the equipment from
the beginning with that in mind. And you can forget about just slapping a
Faraday cage on to it. "Cage" won't work. Aluminum foil won't work.
Think more in terms of alternating layers of aluminum and a magnetically
permeable material like steel, mu-metal, or one of the MetGlas alloys.
It'll cost you. You'll have to check the literature for ideal thicknesses
and spacings. Holes are bad, but if you need them, more small holes are
better than fewer big holes. Chimneys on your holes would help.

Do something about those antennas bringing the effects into your box, like
the power cord, and cables to the keyboard and monitor. I'm not sure what
it would take to filter that, but it may involve Zener diodes, engineered
spark gaps, and other things of the sort. Peronsally, I would use spark
gaps whenever possible, just on general principles. Fiber optics are
good. Just do something about the holes that bring the fibers in and out.

Any wiring layed out is an antenna, receiving flux proportional to the
enclosed area. Loops are bad. Connections between components should be
made with coaxial cable, or something of the like. The components should
have voltage protection right on the pins, and if possible should be rated
to much higher voltage and power than you'll ever need.

And at this point I've really reached my limits.
 
R

Robert Morein

Jan 1, 1970
0
Activ8 said:
On Thu, 3 Jun 2004 20:36:23 -0400, Robert Morein wrote:
[snip]
All I had to do was google EMP and I got more than enough info

I did, but I found no hard info on the shape and duration of powerline
disturbances.
Is it DC? Is it ringwave? Peak voltage?

These things matter.
 
R

Robert Morein

Jan 1, 1970
0
Gregory L. Hansen said:
As I understand it, the EMP comes from the gamma flash stripping electrons
from atmospheric molecules, and they can bounce around for many minutes
before settling down.

Hardening equipment against nuclear EMPs is sort of a specialized topic, I
don't know much about it. But you should really design the equipment from
the beginning with that in mind. And you can forget about just slapping a
Faraday cage on to it. "Cage" won't work. Aluminum foil won't work.
Think more in terms of alternating layers of aluminum and a magnetically
permeable material like steel, mu-metal, or one of the MetGlas alloys.

I find no evidence in the literature that anything other than a Faraday cage
is required for complete protection, although it is possible that the
environment close to a nuclear blast might require what you describe.
You are probably reasoning that powerful magnetic fields could induce
potentials INSIDE the Faraday cage. However, although a Faraday cage is
permeable to constant or slowly changing magnetic fields, it rapidly becomes
impermeable as the frequency goes up, due to the skin effect. And the
induced EMF is proportional to the rate of change of the flux.

Check out http://www.tfd.chalmers.se/~valeri/EMP.html
One author, with uncertain credentials, claims that antennas less than 30"
in length, are "safe". The context is not given.

But in this case, I don't have a Faraday cage. I'm not trying to harden
against nearby nuclear explosions, because, as others have remarked, there
would be other things to worry about. Nevertheless, one can approach a
Faraday cage in little steps. By isolating a local system from long
antenna-like structures, such as power lines and unshielded network cables,
it is possible to reduce the potential difference that can be induced
between parts of the system. All this has been proven in terms of protection
from lightning strikes. Two computers in different parts of a structure but
connected by a network cable can have lightning damage over the data cable,
because of ground currents, some of them caused by transzorb-based surge
protectors.

In particular, this means that CAT-5 cable should be replaced by optical.
Any cable that can serve as an antenna should be shortened to the minimum or
bundled correctly. And I have isolated the cable modem with a 3' fiber optic
link.

Power protection is more vexing. Transzorb based protectors limit the spike,
but tend to "light up" the ground. Current-dumping protectors provide better
control of lightning transients, but in the presence of a prolonged surge
simply follow the waveform up.

Isolation transformers provide the best common mode suppression, but
typically incorporate rudimentary or no normal mode suppression. I have
added two isolation transformers in front of my UPS'es, which contain
tranzorbs. If I knew something about the kind of waveform induced by EMP,
I'd have a better idea how to optimize power protection.

If futile against EMP, my efforts are hardening my home network against the
occasional "superbolt", which is a particular kind of strike that has about
100X the energy of a typical lightning strike.
 
R

Robert Morein

Jan 1, 1970
0
[snip]>
Do something about those antennas bringing the effects into your box, like
the power cord, and cables to the keyboard and monitor. I'm not sure what
it would take to filter that, but it may involve Zener diodes, engineered
spark gaps, and other things of the sort. Peronsally, I would use spark
gaps whenever possible, just on general principles. Fiber optics are
good. Just do something about the holes that bring the fibers in and out.
There are some statements that spark gaps are too slow to catch the
risetime.

In fact, there are two completely opposite descriptions of the nature of
EMP.
One describes it as a phenomena in the 10mHz - 100 mHz range.

Another describes it as in the 60 gHz range, almost sub-light, claiming that
as a result, it leaks through small gaps in a Faraday shield, and is far too
fast for a spark gap.

Ovonics is said to be working on a protective solid state device.

This is vexing, because there are high-tech spark gaps for about $40 each,
which contain replaceable gas tubes.
One claims, somehow (additional device?), to limit EMP to a mere 20 mv.
But there are some statements that these devices are useless, because of the
risetime.
 
A

Activ8

Jan 1, 1970
0
Activ8 said:
On Thu, 3 Jun 2004 20:36:23 -0400, Robert Morein wrote:
[snip]
All I had to do was google EMP and I got more than enough info

I did, but I found no hard info on the shape and duration of powerline
disturbances.
Is it DC? Is it ringwave? Peak voltage?

These things matter.

I don't recall finding that, but I did find out that a Radioshack
bulk tape eraser was a good way to test an enclosure. I also found a
copy of the Army Corp of Engineers plans for secure comms
enclosures.

So if you find that article or the Gauss of the eraser, and the
pulse duration (I'd suggest googling on nuclear blasts, too) you can
do a little math to get an idea of the magnitude of the disturbance
and pick a supressor.

I think a little more googling will get you the info you need. I
found thids much in 1 min

"As it travels into a facility, a transient changes forms ¡X due to
the impedance of the wiring and transformers ¡X from an impulse-type
event to a ringwave-type event. The natural inductance and
resistance of the wiring infrastructure will create a typical
ringwave event of 100 kHz. This is why you can use much smaller
components at a wall outlet or surge plug strip than what you would
use at a panelboard or service entrance. You see much lower surge
currents at the downstream locations."
 
A

Activ8

Jan 1, 1970
0
I bet the odds are much better for a smallish (500m to 2km) asteroid to cause
damage to your infrastructure.

I wonder what the odds would be for meteor impact vs terrorist nuclear bomb?

If we keep killing terrorists, I'd bet on the rock.
 
R

Richard Henry

Jan 1, 1970
0
John Larkin said:
By the time there's enough EMP to zap your gear, you're probably dead
anyhow.
Why worry about this?

The earliest documented civilian EMP damage occurred in Hawaii during US
atmospheric nuclear tests in (or over) the Pacific islands. To the best of
my knowledge, no one in Hawaii was killed or injured directly by the
radiation, blast, or thermal effects of the tests.
 
S

Scott Stephens

Jan 1, 1970
0
Robert said:
I want to implement a degree of protection from nuclear-induced EMP for my
home electronics, principally my computer network.

Consider your context!

There is a real good army manual on how they shield mil-spec hardware.
Perhaps someone will post a good URL since you're past your 2 minutes
with me =(
Comments/info appreciated.
http://www.fas.org/spp/starwars/congress/1997_h/h970716u.htm
http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/3-3-1/appc.pdf
--
Scott

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