> (In theory the grid tries to keep somewhat accurate time, but in practice at least on the west coast the departures can be pretty substantial.) I was under t

> (In theory the grid tries to keep somewhat accurate time, but in practice at least on the west coast the departures can be pretty substantial.) I was under the impression that even though the frequency drifts can be substantial, the grids compensate so that the total number of cycles over a longer time matches pretty exactly what the target frequency would have given? I.e. if the target is 60 Hz, and 61 Hz happens for an hour, then the grid will later on intentionally go down to 59 Hz for an hour (or, perhaps more likely, a frequency close to, but below, 60 Hz for a longer time) to compensate. This is an easier task than targetting a fixed frequency, because the total number of cycles is just a matter of counting and crude intentional drifts for compensation. And it's the total number of cycles that AC-synced clocks use, so they might run slow or fast for a short while, but will then correct themselves by running faster or slower later on. Can someone more knowledgeable comment?