[time-nuts] 60hz disciplined watch

Jim Lux jimlux at earthlink.net
Wed Apr 20 15:53:01 UTC 2011


On 4/20/11 8:26 AM, Poul-Henning Kamp wrote:
> In message<BANLkTimuxPs8gBxP99ra8iJzvhEotp8ong at mail.gmail.com>, paul swed writ
> es:
>
>> Thats what I also thought though did not plan to test it.
>> As for mains stability. They are indeed stable over time weeks and months
>> and are corrected.
> Are you sure ?
>
> Here in europe that was lost in the "privatization" of the grid: Nobody
> was charged with paying for the extra power needed to capture lost
> cycles, so now they just try to keep it close to 50.0Hz and don't
> care about the integral.
>
> I would be surprised if it were any different in USA.
>
It's probably somewhat better, because there are long distance 
transmission lines which rely on careful management of relative phases 
(and by extension frequencies) to control the power flow on the line.  
California consumes about 50 GW (peak)   (26 GW for Ca Independent 
System Operator as I type this).  The two Pacific Intertie lines (one AC 
and one HVDC) carry 7GW-ish.  That AC line is quite the challenge to 
stabilize (it's 1000km long, and I've heard that transients take hours 
to die out). (and, of course, they use GPS heavily to provide an 
accurate time reference for reporting instantaneous phase and amplitude 
of the lines)

I seem to recall a site somewhere that gave statistics (in quasi real 
time) of the system frequency here in Southern California.



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