low-freq EM pulse in carlsbad, california

[capybara]

last weekend, my friend was in Carlsbad, a half hour from my house. the power went out,
and cars stopped dead in the street. (mainly older cars, many newer cars, perhaps with
better shielded sparkplug cables, kept running). our power company , sdge, said the outage
effected 2 blocks and was due to a low-frequency EM pulse.
>>>>WTF? has anyone hear of such a thing? There was no explosion heard so i dont understand
what couldof caused a low freq EM pulse that could cause a power outage and stop cars in the street.
XP-lanation please ???

 

[XMan]

It's possible to build a device to produce electromagnetic pulses without an explosion, I believe. They're a lot more powerful if you mix in some explosive to compress the coils as the charge goes through them. There was a cool article in Popular Mechanics about this subject a couple months ago; apparently the parts to build such a device are around $300.

 

[phrawd]

I live in Carlsbad Seen Ocean's Eleven? That has a low frequency EM pulse similar to the one you're talking about (but yours is on a much lower scale). Broken Arrow has one too (following a nuclear blast). I don't know much about what non-EMP bombs can produce a powerful enough pulse to disable things on a multi-block scale, but I do know that a device made only a few feet long could take out a city block. I really can't answer many of your questions, EXCEPT that it most likely wasn't the spark plugs that were disabled by the EMP (causing cars to die) but rather their computers onboard that dealt with timing the sparks. Spark plugs don't have any semiconductors in their circuits except the computers, as far as I know, so I don't think they would be affected.

 

[XMan]

Originally posted by: phrawd
I live in Carlsbad Seen Ocean's Eleven? That has a low frequency EM pulse similar to the one you're talking about (but yours is on a much lower scale). Broken Arrow has one too (following a nuclear blast). I don't know much about what non-EMP bombs can produce a powerful enough pulse to disable things on a multi-block scale, but I do know that a device made only a few feet long could take out a city block. I really can't answer many of your questions, EXCEPT that it most likely wasn't the spark plugs that were disabled by the EMP (causing cars to die) but rather their computers onboard that dealt with timing the sparks. Spark plugs don't have any semiconductors in their circuits except the computers, as far as I know, so I don't think they would be affected.

That's correct, any car that didn't have an electronic system controlling would work fine - IE, one with a carb, etc. I guess that's why Mad Max drove what he did . . .

 

[blahblah99]

Originally posted by: Xerox Man
It's possible to build a device to produce electromagnetic pulses without an explosion, I believe. They're a lot more powerful if you mix in some explosive to compress the coils as the charge goes through them. There was a cool article in Popular Mechanics about this subject a couple months ago; apparently the parts to build such a device are around $300.

Yeah, I read that article too.. it was in Popular Science last year. The article showed in sketchy details the design of such a device. They said it would cost about $400 and anyone with access to common everyday materials could make one powerful enough to take out a city! :Q

The original theory for a non-nuclear EMP producing device, thought up in 1927 by Dr. Arthur Compton to study atomic particles, makes use of injection of plasma into low electron count elements. By the mid 1980s, scientists had found ways to build a high energy device that, without resorting to a nuclear blast, could emit a huge EMP. Test drops of devices using B-52s and Cruise Missile airframes demonstrated the feasibility of the technology. A one time explosive device provides kinetic energy required to rapidly build an electromagnetic field through electromagnetic induction rather than through the nuclear chemistry found in a nuclear explosion. A second, low cost technology uses a moving short in a tube fed by a charging system. This technology, known as FCG - Flux Compression Generator, turns out to require far less cash to develop and manufacture.

The mechanical construction of the FCG is actually quite simple -- an effective design of such a device can be accomplished by a college graduate in electronics or physics. Because of this fact we will not discuss the details for security reasons. Suffice to say that the non-nuclear EMP device can be manufactured anywhere a machine shop and electronic supplies are available. The electronics and explosives, while not available at your local Radio shack or hardware store, are, never-the-less much easier to procure by terrorists than any type of nuclear materials. Build the device's structure, add the electronics and explosives, and all you need is a timer to set off the explosion. Today, universities are already building prototype devices for further exploration of EMP weapons designs as well as non-lethal devices for use by police to disable vehicles. Countries such as India and several other asian nations are working on both devices and countermeasures.

Detonating the EMP device in the air or near the top floors of a skyscraper maximizes the effects. Defenses include Faraday cages (similar to screening in that which is to be protected), however other effects, including one called "late time effect" may be able to get pass the Faraday cage protection.

The EMP bomb is only effective in a finite area about the device. The larger the armature of the device, the larger the electromagnetic field produced. Thus a device could be one foot across and take out very localized equipment, say a control facility or communications system. A device four or five feet across could be used to take out all communications at an airport or from a skyscraper take out the semiconductor devices for several miles in a swath extending out in all unshielded directions.

The EMP device's somewhat sophisticated mix of mechanical and electronics make it harder to design and thus given the same starting date for the program as an RDW, the EMP device would take longer. Estimates are from 6 months to two years. Cost is estimated to around $1000 for a small prototype to up to $10,000 for a large production line device effective over several miles. However, several sources indicate that a FCG might only cost $400 per device in a production environment.


Availability

Today EMP devices are technologically feasible weapons to manufacture. Except for the difficulty for the average person to obtain the actual design specifications, the weapons can be constructed with materials available to governments and individuals alike. Through low level black market contacts this type of weapon could already be available to terrorists -- for instance the same dealers who sell terrorists their guns probably would be able to find someone to sell them the explosives and electronic components for the manufacture of an EMP weapon. And of course in some cases explosives are already in the arsenals of most terrorist groups. With nations like Iraq, Iran and possibly Libya, Syria, Lebanon, and North Korea who have terrorist connections, the opportunity for both explosive and electronic compoent sales to terrorists is at an all time high. Full up, ready to deploy weapons may find their way to the clandestine weapons market at any time.

U.S. Director of Central Intelligence Tenet reported to Congress after 9/11 that while there is no conclusive proof any nation or terrorist group has created an EMP weapon, however there is also an alarming absence of proof that the devices have not been in production.. Reports out of Asia indicate that at least one country, India, has been building such a weapon, "for peaceful purposes" in order to study its effects and perhaps to build safeguards against it.

Since it is expected that at least one nation has begun work on an EMP devices several years ago, it is quite possible the design is available to terrorists today.


Do not try this at home!

 

[singh]

What kind of shielding would be required to protect critical circuits? Would a circuit enclosed in a metallic sphere of some kind be resistant to an EMP?

 

[XMan]

Originally posted by: singh
What kind of shielding would be required to protect critical circuits? Would a circuit enclosed in a metallic sphere of some kind be resistant to an EMP?

Do a search on Google for "Faraday cage."

 

[glugglug]

Actually, a lot of cars old enough to use carboraters (sp?) would still have a computer onboard. Cars have used 8088s & such since the early 80s, maybe even late 70s.

Newer cars have much better processors, i.e. the transmission in a Saturn is controlled by a PowerPC chip. These probably require better shielding to meet FCC regulations with the higher clockspeed.

 

[glugglug]

There are EMP guns used by law enforcement in some areas to stop people who don't pull over willingly.

Don't know of anything used on the scale you are talking about however.

 

[DeschutesCore]

I know this was in a movie as well, but from what I was told by an EE, a blowing Electrical transformer can release a small EMP.

DC

 

[PowerEngineer]

Hmmmmmmm....

This doesn't sound right to me. An EMP is essentially a flash of electrons ripped from their atoms and propelled away from a nuclear (like) blast. The concern for power companies is that the power lines form what amount to huge conducting loops, and the EMP passing through these loops induce huge voltages that cause flashovers and zap connected control/protection equipment. I doubt that an outage in such a small area could have been due to an EMP (but I could be wrong).

The bit about cars stopping in the street is also hard to understand. What had to be done to get them started again? I'd expect that an EMP would have caused the cars to stop because they had their electrnics permanently fried.

Was there anything in the local papers or on the TV news that might add more details?

 

[Yossarian451]

I agree with you power but I beleive you acn get low level emp wich can just disrupt flow, or overflow some circuit, maybe damaging smaller electronics, but generally no harming all elevctronics. But if the radius was as big as it sounds, I doubt it would have been at a low enough level not to have done any harm. A while back I had tried to design a device which would create a small directed burst of emp, say to disrupt a computer or otehr small ranged electrical system. I never built it but had some ideas. But it sounds like it was something bigger and fishier, maybe bs, maybe not. Also it could have been caused by one of the power substations, where you see the 20 x 20 fence with a bunch of large capacitors, that sparked in parrallel could casue something like this.

 

[blahblah99]

All car ecu's are encased in metal for the purposes of interference... so if cars got stopped because of the emp pulse, it probably hit the spark plug wires, or the unshielded wires connected to the ecu.

 

[Peacekeeper100]

I would think the newer cars would have shielding for the computers so that's why they didn't blow, at least for small pulses. If the EM pulse was large enough in theory it could have caused multiple sparkplugs to fire at the same time stalling the engine. Considering the fact a pulse would add power I don't see what else it would do. If your talking about late 80's cars then the computers might not have been shielded well enough, or the wires from the sensors. In IC circuits it creates a high voltage over all the circuits, and least causing the logic to go bad, if not fry the chip.

I would think anything that had a sudden surge of power could have caused a pulse. Say a transformer got shorted at the end of the windings. Or an EXTREAMLY high current in a voltage line, but that would create a pulse miles long and is unlikely. Any military bases near you there? The military could be testing something.

 

[JustinLerner]

Seems sort of unusual that only older cars were affected, because an EMP pulse should have more effect on newer cars with electronic ignitions, electronic fuel injection, etc. Older carbeurators that are soley hydraulic/electrical/mechanical would not likely be as affected as electronic devices. All cars having onboard controllers for anything should have been affected.

Actually, EMP pulses sometimes happen, but if the power company said this was the cause, they must know more than they say.

Usually the source for EMP is the military aircraft which have ECM capabilities. These aircraft, including the Navy/Marine Corp EA6-? and other ECM aircraft have the capability to blow up TV's, radios, etc by using certain ECM capabilities. The source of the problem was more likely to be your local military aircraft flying somewhat in the vacinity and some officer at the ECM controls probably hit the wrong button. This occasionally happened (every few years) at a base where I was stationed on the east coast of the US. Nevertheless, this doesn't sound like the cause in this instance, since the power company seems to have knowledge of the cause. Also, military ECM is not used in populated areas but only on certain remote ranges, which you all should find a relief.

Stuff happens.

 

[PowerEngineer]

Reading through this post again, I'm still puzzled. It is possible that a failure in a substation (that causes the electrical outage) also results in a momentary (i.e. fraction of a second) increase in EM fields in the immediate vicinity. The frequency would probably by low (60-180 Hz) which is harder to shield against. I suppose it's also possible that some sort of electronic interference (such as military ECM) might have caused both the power outage (by interfering with protective relays) and other reported effects.

The fact that the cars affected were mostly older cars is really odd. No way the spark plug wires would have been damaged...maybe the coil, but I doubt it. Still makes no sense to me.

 

[CTho9305]

I thought an EMP permanently fried stuff... at least an EMP big enough to have any effect. I could see how a small enough one might just appear to be invalid data to a computer, but then would it have that kind of range?

 

[zephyrprime]

Seems sort of unusual that only older cars were affected, because an EMP pulse should have more effect on newer cars with electronic ignitions, electronic fuel injection, etc.

The thing is, even the "older cars" that capybara mentioned were probably cars made in the 80's or even early nineties. They would almost all have electronic control systems.

 

[Peter]

EMP pulses can zap any kind of car ignition ... the pulse goes into the low voltage circuit going into the ignition's high voltage coil, toasting the high voltage stuff.

Survivors normally include cars that happen to have very little open space under the hood, and for sure all older Diesel engines that run fully mechanically.

For european cars, that would mean pre-1992 diesels. With otto engines, it's always luck of draw, no matter how old, or electronic or not. I'd predict the early electronic injection ones (1977 onward) and early electronic ignition ones (1983 onward) are the most vulnerable.

But even with the survivors, chances - with a strong EM pulse - are the starter motor will be zapped too. So on the bottom line, EMP paranoid want an old Diesel with a mechanical gearbox, so you can push the car to make the engine turn and start.

My favorite EMP movie: Until The End Of The World, 1991, Wim Wenders.

regards, Peter (from the town where the Diesel engine was invented)

 

[capybara]

well one thing it WASNT was a power company (sdg+e) transformer blowing,
because we have had a transformer blow in our alley about 5 times in the last 10 years
and it makes a VERY LOUD explosion-like sound. this, however, was a quieter occurance.
>>>>no, i dont know if any of the cars were broke in any permanent way,
maybe just temporarily stalled.

 

[Mingon]

FYI, EMP bombs are not much use in all honesty as they are very easily shielded against. I spent a couple of years doing some research work on exploding wire plasma using a 50,000 kv capacitor bank. The data collection was done about 30ft away in a faraday cage with no problems at all. Whilst current media reports hint at the use of emp bomb's in iraq via the blu series of US Bombs their effectiveness is not that great.