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.