Quoted:Sure, no specific EMP tests have been done, and obviously can't be done.  But the facts are:

1) EMP field strength disperses/weakens to the cube of the distance.  In other words, strength drops quite rapidly as distance increases.
2) The spark plugs in a car create quite a bit of EMP, and they're also damn close to a lot of computery stuff underhood
3) The Faraday cages around the computery stuff in the car protect them from EMPs, whether from a spark plug or nuclear bomb
4) Yes, long conductors, like the transmission lines of our electric grid, are more likely to have potential issues with EMP.  But power lines are frequently and routinely struck by lightning, which is a hell of a lot more voltage and amperage than what would be generated by an EMP.  Yet lightning rarely brings down any significant part of the grid.  Why is that?

Quoted:

Not an "expert," but I appreciate the shout-out. I work with the HV transmission grid every week (substation operator0, but I'm barely 25% of an engineer or designer.

Yes, a CME or other solar (or cosmic event, such as a strong source of cosmic rays bombarding us from nearby) could happen any moment. Usually we get about 3 days warning for a strong flare or minor CME, something that can fuck up satellites and comm systems but not so much hurt the grid.

The Carrington Event arrived in something like 17 hours. We've seen many other strong CME's that weren't pointed right at us travelling at similar speed. For reference, the sun is about 8.5 light-minutes away, so 17 hours is an eternity in light speed terms, but a very short time for human reactions.

It's my (limited) understanding that the charged particles streaming past the lines/equipment cause potentially serious voltage spikes. Voltage causes "movement," amperage causes "heat." Too much amperage melts things, too much voltage twists things. But, there's a more insidious damage. High voltage breaks down electrical insulation. It jumps gaps (movement). That's why as the voltage climbs, the size of insulators, amount of insulating oil/gas and size of equipment, and minimum approach distance increases.

A transformer is a miracle. And yet, it's nothing more than two windings of conductor surrounding a specialized iron core, bathed in oil and insulated by paper. The reason transformers are so important is the loss of power on lines. You lose power when transmitting it equal to the current squared times the resistance of the conductor. (I^2)R. So, if the dam/coal plant/nuke plant/wind farm/what the fuck ever is generating at, say, 50KV (they don't, it's usually 34.5KV or something like that, but 50KV makes my example math easier) and you need, say 50MW to feed your town (load center), you have to produce 1000 amps. That's because Watts = Volts x Amps. So, 50,000 volts x 1,000 amps = 50,000,000 Watts, or 50MW.

BTW, 50MW is a small load. Big cities use gigawatts, billions of watts.

Anyway, a mile of conductor might have an ohm of resistance. So, your losses on that line, per mile, are (1000^2)x1, or 1,000,000 amps per mile That's a lot of heat, and you can't push that power very far without either losing it or melting the conductors (in reality, we'd be talking AC power instead of DC, inductance vs resistance, but the concepts are the same).

What a transformer does is simple. One of the windings might be, say, 10x as numerous as the other winding. To create electricity, you need three things. A conductor, a magnetic field, and relative motion between them. The generator creates the electricity with either a stationary coil of conductor with a spinning magnet in it, or vice-versa. That relative motion between the two creates electrical flow. The transformer does the SAME THING, but it has two different windings, agains, let's say in a 10-1 ratio. Separated by nothing but paper and oil. The primary winding gets the flow of electricity from the generator. The constant flux of the collapsing/expanding AC electrical field creates the relative motion, 60 times a second. The combination of those two induces an electrical flow in the secondary winding.

the next concept is constant power. Watts don't change, just volts and amps. SO...if I pump 50KV at 1000 amps (50MW) into the primary, and the turns ratio is 10:1, the secondary gets 500KV at 100 amps (also 50MW).

NOW, the line loss is (100^2)x1, 10,000 per mile, instead of (1000^2)x1, 1,000,000 per mile. The transformer has cut the amount of electricity I lose transmitting it by a factor of 100. I can now transmit the electricity 100x as far with the same loss. At the other end, I reverse the process with another transformer to provide the amps required to power the equipment at the load center.

That's the basics of the power grid. Without transformers, you'd all have to live VERY close to the generating station to get any power at all. Transformers literally power civilization with their magic. No moving parts, just coils of wire, iron, oil, and paper in a big steel case.

Where do the CME's come in? Over-voltage destroys insulation. It will break down the oil/paper insulating value as the charged particles stream past the conductor, inducing a high voltage (remember, conductor + relative motion = electricity...the movement of the charged particles past the conductor does this). When the two winding in the transformer lose the insulation between them, and short-circuit to each other...




...Civilization ends. All at once. And won't be coming back. We don't have replacements for the transformers. No one does. They take years to make, months and months to move, and huge quantities of money. Not to mention raw materials are in short supply., and you need electricity to produce more of the magic core steel and everything else involved to build them, a Catch-22.

Experts have testified that the loss of power in this country would result in a 90% population loss in the first year. We have 57,000 substations, and the loss of the correct 9 of them could result in an 18-month power outage to large parts of the country. No, I don't know which 9, but others do.

Now imagine if a CME took out 57,000 of them all at once. And all the others over half of a globe, or the entire thing in a sustained event.

Save that last bullet for yourself.

So, that's my apocalypse story for today. I know how civilization will end, because I watch this system crumble around me every day.

Happy Thanksgiving.