Generators are not in sync with the grid though. And that's the hardest part.
Here's why generators were running here despite the grid being available. A generator has a very short lifetime and in order to prolong it, some owners learned to run those in the very optimal schedule. Which sometimes requires a minimum amount of time to run in a single cycle. Thus if you started it you are committed to run for X hours.
> Generators are not in sync with the grid though. And that's the hardest part.
I know. What's interesting re: Ukraine is because there are so many generators there are more options to getting power sufficiently restored for normal life than just rushing to restore the entire grid.
> Thus if you started it you are committed to run for X hours.
I'm skeptical this is the main reason. While fast starting a diesel generator is hard on it, there are other, slower, ways to start big diesel generators with minimal impact on lifespan. The blackouts in Ukraine are almost all on a schedule, so big buildings with dedicated staff and expensive generators can and do startup their generators in advance (I've personally heard this happen on occasion - big generators spooling up multiple minutes in advance of the scheduled blackout).
Also, it makes sense to turn on generators in advance anyway: gives you a chance to diagnose any issues.
Perhaps not the main reason, but heavy devices do indeed require minimum amount of time running. I think small devices as well but not as long. Honestly I don't remember what we did back then: so many things were going at the same time, longevity of generators was not very well know at the time )
Here's why generators were running here despite the grid being available. A generator has a very short lifetime and in order to prolong it, some owners learned to run those in the very optimal schedule. Which sometimes requires a minimum amount of time to run in a single cycle. Thus if you started it you are committed to run for X hours.