Eli5 how could an electromagnetic impulse, say from the sun for example, disable a whole power grid?
In: Physics
Just to add another aspect to the other good explainations:
As well as an electromagnetic pulse causing damage to various individual bits of equipment in the grid, one of the biggest problems is that it affects a wide area all at once.
Most grids are designed so that if any single piece of equipment fails, there will be a short blackout when the broken equipment is automatically disconnected. A blackout is how the grid protects itself from being further damaged by the faulty equipment (by making too much electricity flow through it, for example). Some grids are really clever and can very quickly restore power by sending it through a different route that avoids the broken equipment.
But, if there’s suddenly lots of equipment everywhere that’s broken simultaneously, that process doesn’t work as well. For example, the equipment that automatically disconnects failed equipment (a circuit breaker) might also itself be broken. This can lead to further damage to the transmission equipment that sends the power around the grid.
As an engineer, you can design systems to be able to handle failures and damage and still continue to work (often called ‘resillience’). The more failures and damage your system can deal with, the more difficult and expensive it becomes to build it. You have to decide that the system will be able to deal with a certain number of failures at once before admitting that it will stop working – if you don’t, the system becomes prohibitively complex and expensive and is not seen as good value – and probably won’t be built.
When trying to figure out the balance of how much failure to tolerate, you look at the risks to your system and how often they occur.
Individual failures happen quite routinely, and potentially cause a lot of damage if not handled. Over a reasonable amount of time, the amount of money you spend on protecting from damage is less than the damage that would have been caused had you not prevented it – making it easy to justify.
A big electromagnetic pulse from a solar flare that has a noticable effect on the surface is a very rare event – and there are relatively few examples of it occurring to study to understand the system wide effects. So it’s hard to know exactly how much damage it would cause, and what we can do to properly protect the system from it, and it’s also hard to know whether it’s likely to happen. That makes it difficult to balance how much you protect from it, compared to how much damage would occur if you didn’t. Often, this leads to engineers (and more importantly their bosses) accepting that if it is to occur, they’ll build in some ways to limit the damage such an event would cause (i.e. ‘damage limitation’), but they won’t try to protect against it completely, because it’s just too expensive and complicated to do so.
Which leads to the outcome that if such a rare system-wide event were to occur, the likely outcome is that the grid will be non-functional for a significant amount of time. The better the design is, the quicker they’ll come back online again.
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