Ukraine is interesting in this context because there are so many generators. In the richer parts of Odesa I've even found it hard sometimes to tell whether or not the grid power is on as literally every single building had sufficient backup generators to keep the lights on (also, many big businesses seemed to run their generators even when the power was on, I presume as a civic-minded way to add generation capacity overall and avoid interruptions when the power flips on and off).
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 )
