The Truth About Solar Storms 91
StartsWithABang (3485481) writes On Wednesday, The Washington Post ran a story about a very large solar flare two years ago that missed Earth, but not by too much. From a scientific point of view, what is it that happens when a solar flare interacts with Earth, and what are the potential dangers to both humans and humanities infrastructure? A very good overview, complete with what you can do — as both an individual and a power company — to minimize the risk and the damage when the big one comes. Unlike asteroids, these events happen every few centuries, and in our age of electronics, would now create a legitimate disaster.
Another ignorant fearmongering article (Score:2, Informative)
"And long, electricity-carrying wires spark, start fires and even operate and send signals when there’s no electricity! This even includes, believe it or not, when they aren’t plugged in."
In 1859, the "long, electricity-carrying wires" were telegraph wires, and there was nothing plugged into anyone's wall as suggested by the image in the article. Yes, there were large DC voltages induced in these miles-long wires: that's because they were MILES LONG. The wiring in your house and personal electronics might have a couple of millivolts induced within: something akin to the power induced when you rub your shoes on the carpet and zap them. (There's thousands of volts there: oooooh, I'm scared! NOT!)
If these solar events could induce significant voltages in meter-sized objects, then you'd have a lot to worry about. The human body is very conductive on the inside. But, I don't hear historical reports of people keeling over dead during this Carrington Event, so I'm not particularly worried about my electronics.
If you're really concerned about what's coming into your house from such a solar event, then all you need to do is walk over to the circuit breaker and turn it "OFF". You won't have power for a few hours, but that should keep you safe from any DC voltages above 150 volts.
Honestly people: your chances of being harmed by a lightning strike are much greater than this silliness.
The failure mode is transformer core saturation. (Score:5, Informative)
High induced votlages in open wires are a problem, but they're not the big one.
The biggie is common-mode currents in long high-voltage transmission lines adding a strong DC component to the current in the substation transformer windings - high enough that when the same-direction peak of the AC's cycle adds to it, the core saturates. Then the inductance of the transformer drops to the air-core value and no longer substantially impeeds the current.
The current skyrockets. The resistive heating of the windings (and the force on the wires from the magnetic fields) goes up with the SQUARE of the current. The windings quickly soften, distort, form shorted turns, melt, open, short out to the frame, etc. The transformer is destroyed, or committed to a self-destructive progressive failure, in just a handful of such cycles - too fast for the circuit breakers to save them (even if they DO manage to extinguish the arcs with the substantial DC component to the current.) Even if the transformer doesn't explode and throw molten metal, gigawatt sustained arcs, and burning oil (or burning-hot oil replacement) all over the substation area, it's still dead.
This happens to MANY of the giant transformers in the power grid. Each set of three transformers that has one or more failed members means a high-voltage transmission line that is shut down until the transformer is replaced.
There are essentially no spares - these are built to order. Building one takes weeks, and there are few "production lines" so little parallelism is available. What is destroyed overnight will take years to replace, while each intercity power transmission line is not functioning until the transformers at its end ARE replaced.
The current occurs because the transformers are organized in a "Y" arrangement, and the center of the Y is grounded at each end (to prevent OTHER problems). The transformers have enough extra current handling capacity to avoid saturation from the DC through that center connection to/from ground from ordinary electrical and solar storms - just not a giant one like we get every couple centuries.
The solution is to put a resistor in that ground connection, to limit the DC in the lines (and dissipate the energy it represents). Indeed, a few lines have such resistors already.
But a suitable resistor is a box about the size of one of the transformers. It's very expensive. And it only makes a substantial difference to the operation of the lines in such a once-in-centuries event. So most executives don't spend the money (and get dinged for costing the company millions) to put them in, to prevent a failure mode that hasn't happened in the generations since Tesla and Westinghouse invented the three-phase long-line power grid.
Or at least they don't until the regulators or their stockholders require it. Which means said decision-makers need a little educational push to decide it's worth the cost and get it done.
Thus articles like this. B-)