[time-nuts] Re: Power lines and time

[Chuck Harris]

Hi Alberto,

The US is replacing meters too, but they are still "Ferraris" electromechanical
meters with electronic readouts.  The power grid will still need to be kept
to a reasonable accuracy for the meters to read with a reasonable accuracy.

The Ferraris type meter (G. Ferraris died 3 years before anyone patented
an electric power meter...)  has been refined to a point where its ultimate
accuracy is 0.01%, but that requires the frequency to be held to a similar
degree of precision.

We have probably allowed this discussion to stray a little far from
"precise time...measurement"  I think I'll rein in my end of things...

-Chuck Harris

Alberto di Bene wrote:

> In Italy, almost all of the meters have been replaced by solid state
> units, which are read remotely through signalling on the power lines. I
> feared that would have meant an increase in radio noise (I am a
> radioamateur), but so far I haven't noticed any. This system has the
> advantage that now the electrical company can apply different rates
> between day and night, without needing that the meter itself is able to
> keep the count of the time. At the start of each period a remote command
> changes  the rate.