Andrew Gabriel wrote:

I'm out of touch now, but CEGB used to keep UK power grid at
50Hz +- 0.1Hz. No one ever came up with a good reason it had
to be that accurate, but they did it "just because they
could", to quote someone I spoke with at the Winnersh control
room about this some years back.


.1 Hz is not an unreasonable standard to keep. The wider the
variation that is allowed in the control loop, the easier for the whole
system to become unstable and shut down as the controls disconnected
equipment from the grid that was too fast, or too slow. You are working
with massive mechanical systems that will self destruct if you allow
sudden changes while under load. Think of what happens when a long
train tries to stop. If the couplings didn't have some play to adsorb
the shot, the train would derail when the engineer tried to use the
brakes. Its just basic physics.


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