[GTALUG] NTP's Fate Hinges On 'Father Time' - InformationWeek

[James Knott]

On 03/15/2015 10:36 AM, Stewart C. Russell wrote:
> On 2015-03-14 10:09 PM, David Thornton wrote:
>> "Keeping time in sync" is a cornerstone to technology from gps to
>> ssl, from hft to big data.
> Absolutely. At the solar plant I audited the other week, I was amused
> to see that the great big huge expensive grid protection and control
> box was controlled via GPS sync. It's the cheapest way to maintain
> grid frequency at the far end of the grid. And I mean /far/; 5 hours
> west of Thunder Bay 


Out in the middle of the Pacific???  The left coast is only 3 hours
behind.  A wavelength at 60 Hz is 5000 Km, though a bit shorter in power
lines.  With 3 phase power, there are 6 points within the cycle where
sync can occur, so power phase will never be more than +- 30° out of
sync, even before adjusting the alternators.  So this means syncing 5000
or 10000 Km away is no different than 833 Km.


For many years the LORAN C navigation network was used as a time base
for the telecommunications industry to sync the telecom network. 
However, it only provided an accurate time base clock, not time of day.