I’ve understood that substations and transformers installed in the past decade at least are “hardened,” so the extent of even that wouldn’t be as great as some seem to think.
No, they would be the first to burn out... The worst part is that there are almost no backups (because they should almost never fail). If you have ever had a transformer blow in your local community, you should know that it takes several days to get a replacement - sometimes weeks. That is because they are specially built to different specifications.
Now take that knowledge and understand that if EMP blew several hundred or thousand of these transformers - how long would it take to replace.
It really is a problem. Even today, if a major transformer goes, it can take several days to replace. Multiply that by a thousand and you can see the problem.
They are not easy to manufacture but they are also not going to blow frequently, so they do not keep stock on hand.
They would have to manufacture them as needed (they do differ tremendously) and with out manufacturing today (or lack of I should say), how long do you think that it would take...?
Oh, and it is not the substations that would suffer the most, it is the transformers that download the voltage so they can deliver power to the individual residences...