[time-nuts] Re: UTC, 60 Hz

Tom Van Baak tvb at leapsecond.com
Thu Jul 28 01:18:32 EDT 2005

> > Certainly.  But what's your point?  I don't see these utilities failing
> > if a second slips here or there.   The one case where time is critical
> > is the power grid, and they keep their own time (Which, IIRC
> > approximates UTC).

The power companies used to use GOES heavily;
early this year the last of them switched to GPS
as a time and phase reference. If there's a power
industry person in time-nuts we'd love to ask you
a few questions.

> The long term average of the power grid in the US is 60.000 Hz.  Short
> term variations from that can and do happen.  It is to make sure that
> the clocks run on time, on the average.  It might be better to say
> that the power grid approximates the SI second, since it has no notion
> of which second it is (although the control infrastructure for the
> grid most likely does).
> Warner

For real plots of 60 Hz mains frequency, including
Allan deviation, see:


The tolerance is good; but so far from the level of
astronomical or atomic seconds that it's not an


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