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PowerLine Surge Protectors

Let Local Lightnings Loose
  (+7, -2)
(+7, -2)
  [vote for,

Recently there has been expressed some concern about the fragility of the electric-power infrastructure. A large solar flare, such as actually occurred in 1859, could destroy transformers for high-voltage power lines, everywhere. See link.

When a solar flare happens it unleashes a huge mass of hot plasma, known as a "coronal mass ejection" or CME. If and when this material hits the Earth's magnetic field, auroras form. It also can cause an ElectroMagnetic Pulse, or EMP.

We know a fair amount about what EMPs can do to modern electrical and electronic technology, because they are also released by nuclear explosions, and we've had plenty of them to study. Basically the pulse, when it encounters a wire --any wire-- can induce a voltage gradient to appear in that wire. If this voltage happens to exceed the electrical limitations of whatever device to which that wire is attached, then the device will probably break, one way or another (most often involving parts heating/melting).

Long-distance high-voltage power lines offer a terrific opportunity for an EMP to induce a truly enormous voltage gradient. Many transformers on the ends of those wires will stand little chance of surviving a flare like the one in 1859. Since the transformers are essential for electric power distribution, just about nobody will have reliable power afterward. That's pretty bad news for Modern Civilization, which is practically defined by its widespread usage of --and dependence upon-- electricity.

So, this Idea concerns a possible way to protect those very important transformers. It starts by noting that long-distance high-voltage power lines, depending on when they were built, tend to carry voltages from 100,000V to 1million V. If an EMP induces a higher voltage in them, then at least we know the starting point!

The wires of such a power line are "bare" (uninsulated) and are held a significant distance off the ground, for good reason. We don't want anything on the ground accidently touching them! (The result would be something like a small lightning bolt, and a very crispy object.)

Now for a slightly different but not unrelated topic. The lightning rod was invented by Benjamin Franklin, and is used to protect things from natural lightning strikes. The way it MOSTLY works involves a sharp point and something that is called "the corona discharge effect". It happens that natural lightning doesn't strike randomly; it only strikes things that electrically attract it. The randomness we perceive derives from physical locations/objects that manage to accumulate some "static electric charge", the essence of the thing that can attract a lightning bolt. A lightning rod can DISSIPATE that charge into the air, via the corona discharge effect, preventing it from accumulating ENOUGH to attract a lightning bolt.

A lightning rod has limits, and it is possible for a charge to accumulate faster than it can be dissipated. The result quite naturally can be a lightning strike upon the lightning rod. In this case the rod can still protect a building, if the rod is thick enough and has a thick electrical cable attached to it, the other end of which is firmly buried in solid ground. The power of the lightning strike is diverted from the building.

And Now For The Idea: At various places along the length of a long-distance power line, let us install lightning rods. These need to be installed in-between the towers that support the power lines. Each would rise from the ground toward one of the lines. It would be separated from the line by a carefully calculated distance. The calculation would involve the working voltage of this particular power line, the average barometric pressure at that location, and the average humidity at that location. When working normally, the presence of the lightning rods should have zero or near-zero effect upon the operation of the power line.

When a CME hits the Earth's magnetosphere and generates an EMP, however, the voltage on the power line rises. We WANT this increased voltage to break down the "air gap" between the power line wires and the lightning rods. Power that could destroy transformers now gets diverted in numerous small lightning bolts along the length of the long-distance power line.

While I thought of the preceding a while back, one key aspect of it was missing. How do we turn it OFF after it has done its job? Each of those just-formed lightning bolts creates a pathway of ionized air molecules that is a pretty good conductor of electricity --and the power line is designed to be carrying a lot of electricity. We could destroy transformers that way, too (the equivalent of an electrical short), if those protective lightning bolts are not made to stop!

I think the answer is to make the lightning rods and their conducting cables out of magnesium. Let's take an example in which the top of the rod is about 80% of the distance between a power-line cable and the ground. When an EMP-induced voltage surge happens, lightning crosses the air gap and is conducted by the magnesium. This flow of power also affects the magnesium and ignites it; it quickly burns to ash (magnesium oxide). The air gap is now increased to 5 times its original distance (from 20% to 100%). The induced voltage WAS sufficient to cross the original air gap, and to create a conductive pathway sufficient for the normal power-line voltage to continue using. But the EMP is short-lived, and now the normal voltage of the power line would need to try to maintain a conductive pathway across 5 times as much air gap, and it will fail THAT task, meaning that the lightning stops.

Will the transformers have been protected? Maybe. I suppose we should try this to find out....

Vernon, Mar 31 2009

The Carrington Event http://science.nasa...carringtonflare.htm
As mentioned in the main text [Vernon, Mar 31 2009]

"Series Mode surge suppressor" http://www.brickwall.com/
If this could be scaled up to high-voltage powerline conditions, installing a bunch of them would qualify as a pretty good solution to the problem. [Vernon, Apr 01 2009]

Line arrestors http://www.abb.no/p...guage=us&country=US
[Ling, Apr 02 2009]

The Geomagnetic Apocalypse — And How to Stop It http://blog.wired.c.../04/2012storms.html
[xaviergisz, Apr 25 2009]


       sorry, since the ionization of the air gap will take time and require tremendous voltage the damage to transformers (which have no ionization delay and can fuse internally) it will not prevent the damage caused by what might be termed an "induction event". While such an event does pose some threat to the power grid as a whole it is far more likely that a moderate event will damage more sensitive electronics (microchips, magnetic media, sensitive inductance circuitry). After a profound event the grid may well be damaged but it will fall into the "least of our worries" category, as power generation would likely also be halted by such an event.
WcW, Mar 31 2009

       On the other hand a chamber with an ionized gap like a huge radio tube might be able limit voltage by means of an instantaneous plasma conduit to earth but it would be complicated and expensive to build a unit large enough to earth a surge large enough to destroy transformers. I think that trying to rely on an ionized arc, (with lighting as fickle as you describe), would be completely unreliable.
WcW, Mar 31 2009

       Yeah, but I'll give him a (+) for the paragraph breaks alone.
normzone, Mar 31 2009

       Even if this kind of device only protects the grid itself, and not the other kinds of damage that a solar flare would cause, it would at least reduce the costs of rebuilding.   

       The real question is whether building these lightning rod surge protectors would cost more, or less, than the infrasturecture repair cost that they protect against.   

       Surely something cheaper than magnesium could be used instead, though. Perhaps carbon rods (such as were used in carbon arc lamps)? They'll burn when heated by electricity, but should self-extinguish once the electricity stops.   

       Oh, and a better solution than making the protectors out of something that gets used up, might be to make them out of something like a bimetallic strip, so that they bend down, away from the power lines, as they heat up. This would allow them to reset themselves after the power surge is over.
goldbb, Mar 31 2009

       I'm not sure why you need it: the higher the voltage the easier it travels through air (witness vanderGraff generators), so maybe just more precisely sized insulators ?
FlyingToaster, Mar 31 2009

       [WcW], the breakdown voltage of air is about a million volts per foot (call it 3 million per meter). While I could not be specific in the main text about how close to a power-line wire we would be able to put a lightning rod, because of the range of normal operating voltages used, the key to this Idea is to make sure the rod is close enough so that it does NOT take a long time for an increased voltage to jump the gap.   

       Next, I'm well aware that ordinary electronic gadgets are quite likely to have their circuitry fried. But that is not nearly as bad a thing, to Modern Civilization, as having all the refrigerators in the Developed World not being able to work for a year, because of blown powerline transformers. At least not yet would fried electronics be as bad as that.   

       Part of the reason I posted this Idea was that even if this particular notion can't work well enough, some other notion might, and getting people to think about it now, before it is too late, is pretty important.   

       [goldbb], Carrington events, according to the linked article, appear likely to happen about once every 500 years, on the average. 1859 was 150 years ago (anniversary of event probably cause of current consciousness-raising about it), but that is no guarantee another won't happen tomorrow instead of 350 years from now. Anyway, if they really do average 500 years apart, then I'd say magnesium is cheap enough to be used for this purpose. The bimetallic strip idea, though, sounds interesting. I'm not sure it will bend fast enough, though, to cause the lightning to break before the trasformers break from the short-circuit.   

       [FlyingToaster], existing insulators that separate power-line wires from their metal towers apparently suffice to prevent EMP surges that have so far occurred (and damaged transformers) from jumping the air gap between the wires and the towers. If we are lucky, a Carrington event pulse WOULD cause electricity to bridge that gap. But then we would be UNlucky, because the gap is short enough that once the electric arc starts, the ordinary power line voltage should suffice to keep it going, thereby causing transformers to fail from the short-circuit. I specified placing the proposed lightning rods in-between the towers so that they are the closest metal around, when induced voltage rises enough for lightnings to start. Then I allow the rods to be destroyed easily by the event, to ensure the electric arcs stop. It may not be the best protection, but I'm pretty sure it would be better than nothing.
Vernon, Apr 01 2009

       So, when we build the Space Elevator(s), will it (they) act a lightning rods too?
coprocephalous, Apr 01 2009

       I suspect that the transformers could be more easily protected using inductive surge protection (capacitance "loads") than by installing air gap "spark plugs". Really the damage to the micro-electronic world would be far more significant than the damage to the power grid in any EMP event. For example, the entire contents of my town's substation could be easily replaced in a few days, but replacing the digital information systems, controls and microchips in every single device would, not so much so. We have a firm here that does nothing but make circuit boards for power control systems, the grid is dependent on such boards and literally thousands of them would need to be replaced before you could get the grid functional again.
WcW, Apr 01 2009

       [V] a "fuse" then...   

       Say you've got as the last bit of your lightning rod a metre-length section attached to the main structure by a hinge on the bottom and a bracket with a fuse-material pin halfway-up.   

       Lightning strikes, the fuse blows and the rod falls away from the wires. To reset just rotate the rod back up into position and replace the fuse-material pin with a new one... good to go for either another 500 years or until somebody thiefs the magnesium, whichever comes first.
FlyingToaster, Apr 01 2009

       [coprocephalous], I'm not sure anyone has yet considered the effect of a CME upon a space elevator. I suspect the answer will be "very bad", since the only thing we know that can work to build the thing is carbon nanotubes, an excellent electrical conductor.   

       [WcW], the surge-suppressor link I added sounds something like what you wrote. Is it?   

       [FlyingToaster], perhaps some additional spring-loading could encourage your version of this lightning rod to fall faster. Under gravity alone, I suspect it will be too slow to break the lightning before a transformer gets damaged. Thanks, though!
Vernon, Apr 01 2009

       I really like the sound of that. A partial rod that melted and fell away if the line power arced over is a good idea. Now what about lighting?
WcW, Apr 02 2009

       I don't see how it would affect a space elevator - the charge would travel straight to the ground and dissapate.   

       +1 for this idea as I'm always worried about those commies and their EMP devices!
DIYMatt, Apr 02 2009

       [WcW], ordinary lightning should not be a problem. Consider that you can mount an ordinary lightning rod on each of the towers either side of the space in which these special rods are grounded. Rods-on-towers would be much higher in the sky than the specials, located as they are beneath the powerline wires. I notice I could have said a little more about how many of these are necessary. Certainly they should be located near transformer sites, but they can also be located at multi-kilometer intervals along the route of a long-distance power line.   

       [DIYMatt], I think there is an intention of having a space station on the other end of a space elevator. Both ends of the cable would be affected....
Vernon, Apr 02 2009


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