You are correct that the direct effect would be localized. However, what would be the secondary effect if all power went out in an area from Buffalo to Chicago? Would the rest of the U.S. Power grid try to compensate for the loss, taxing the grid to the point where other sites start to collapse, with a domino effect of taking the whole system down? Or would the grid have the intelligence to automatically break off the parts of the country that drop, preserving the integrity outside the primary area?
I'm asking if this is possible, because I don't have the background in power systems to know.
It would be dark, for a while, if it happened at night. Likely some areas into the next night.
Would the rest of the U.S. Power grid try to compensate for the loss, taxing the grid to the point where other sites start to collapse, with a domino effect of taking the whole system down?
If it went down, there is no load to pick up. The connecting lines are limited to their capacity, the relays are not going to let too great a power pass. If the protective relays are not working, the line is down and no power passes.
Or would the grid have the intelligence to automatically break off the parts of the country that drop, preserving the integrity outside the primary area?
Yes, the dark areas would be limited. Possible to be large for a while, but not unlimited.