[time-nuts] Power lines and time
phk at phk.freebsd.dk
Mon Aug 22 10:23:04 EDT 2005
In message <4309DA8E.9040801 at erols.com>, Chuck Harris writes:
>> Uhm, sorry, that is just plain wrong. The Ferrantis (sp?) power
>> meter which is the most widely used meter in the world is not
>> frequency sensitive within a band of +/- 10% or more.
>I have never seen a power meter made by Ferranti in the US. Landis-gyr,
>definitely, but not Ferranti. To quote Landis-gyr's website:
Sorry, not "Ferranti", but "Ferraris" and not "made by", but "principle".
You can read about it here:
>Here most of our meters are of the induction type, which work on the principles of a
>split-phase induction motor. They are very easy to recognize by their
>horizontal 4 inch corrugated aluminum disk that rotates (hopefully) slowly.
That is exactly the kind I'm talking about, only they're not exactly split-phase
because the offset fields are current vs voltage.
Their frequency sensitivity is very low compared to other error
factors. Most of the installed meters are class 2 (ie: up to 2%
wrong) or worse and frequency is seldom allowed to fluctuate +/- 1%
in any civilized grid.
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