Re: power-grid physics - clocks

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

Hmmm...distinguishing between short term variations, and diurnal variation:
the former can be quite large - and the latter is rather low.

I have heard of line frequency deviations of a significant fraction
of a percent, short term.

Brian W

At 12:17 PM 8/21/2003 -0400, you wrote:
> One satisfying way to explain this to students is to talk about the
> typical consumer synchronous clock.  An electric clock using 60 Hz po=
> wer
> as its time base is pretty accurate.  There are 86400 seconds in a da=
> y.
> In order for a clock to run within one second per day the daily
> frequency accuracy must be within one part per 86400 or roughly 0.001=
> %
> or roughly 60.00x Hz and approaching 60.000x Hz.  I believe this is t=
> he
> correct ballpark.  Our synchronous clock in the science building lobb=
> y,
> as periodically checked against NIST, is generally better than one
> second per day barring blackouts and other power glitches.
>
> Michael D. Edmiston, Ph.D.
> Professor of Chemistry and Physics
> Bluffton College
> Bluffton, OH 45817
> (419)-358-3270
> edmiston@bluffton.edu
>
>
> Tom Bross wrote...
>
> What could I tell students are the number of significant figures in t=
> he
> frequency of the AC available in the lab outlets?  Is is 60 Hz, 60.0 =
> Hz,
> 60.00 Hz, etc.?  At least what would be a reasonable estimate?


Brian Whatcott    Altus OK    Eureka!