There was an article in the amateur radio magazine "QST" in which
someone built a line or mains monitor.  The author had a very accurate time
base and stated that the mains frequency seemed to drop a little during
the wee hours of the morning and then come back up as the day wore on.
Since modern power distribution systems are made of hundreds and thousands
of generating plants tied together in a grid, the system tends to keep
itself synchronized by the fact that the generators tend to be pushed faster
by the rest of the grid if they attempt to slow down and the grid makes it
impossible for them to speed up if something tries to throttle them up.

        What this means is that any power grid acts like a giant spinning
wheel with lots of inertia.  Maybe somebody on the list knows how many major
grids there are in the Americas.  Each one will be a separate frequency
generator.

        The original message was about Australia, but I think the same
holds true for that part of the world except for the 50 HZ frequency.
I suspect the big grids have better frequency regulation than a small grid.
Of course a gasoline or Diesel generator is going to be as good as the
governor on the engine which may not be very good when one is talking about
a clock.


Martin McCormick WB5AGZ  Stillwater, OK 36.7N97.4W
OSU Center for Computing and Information Services Data Communications Group