Hi Back in high school (electricity had indeed been invented) somebody noticed that you could actually watch an electric line clock slow down / speed up by a fraction of a second around 5 pm. All you needed to see it was WWVB and a clock with a nice big second hand. Get is set right on at 4 pm and it would be off by 5 pm. It would catch back up again later in the evening.
For the curious, this was after the area had been re-wired for 60 Hz instead of the original 25 Hz. Never could figure out some of the old 25 Hz stuff .... Bob On Apr 10, 2010, at 2:17 AM, Bill Hawkins wrote: > Read the quote again, please. Their line clock was *faster* than the > satellite clock. When they reduced mechanical power to slow their > line clock to track the satellite clock, the customer's clocks slowed > down. The satellite clock was slow. > > There's an analogy for this power versus frequency thing. Say you > are driving at 60 (kilometers or miles per hour, doesn't matter). > You start to climb a hill, placing more load on the engine. The > speedometer drops to 59. Your cruise control or your foot increase > fuel to the engine to get back to 60. When you go down a hill, you > have to reduce fuel because the load has decreased. > > When you're driving, you can see the grade changes. The power company > can't see the load changes coming, and has to react after cycles have > been lost. They have to generate (at 60 Hz) 60 * 3600 * 24 cycles per > day to keep the synchronous clocks happy. Ah, +/- 60 for a leap second. > > Bill Hawkins > > > -----Original Message----- > From: Thomas A. Frank > Sent: Friday, April 09, 2010 11:52 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Yukon Energy causes time sync problems > >> In this case, the reference clock appears to refer to GPS satellite >> time, >> but >> uses a standard wall clock to display it. It is the reference clock >> that >> slowed down when it should have failed to work at all. Perhaps the >> wall >> clock >> (maybe it was really a HP 113) needed oil. There's the real >> question for >> time >> nuts: How did the reference clock slow down? > > I just went and re-read the article. It reads to me that the > synchronous clock, not the GPS reference clock, was what suffered the > problem. > ----------- > quote: > The control centre's wall clock was running faster than the satellite > clock over the last few days, so staff simply turned down generation > as they normally do, without knowing there was an internal problem > with their electric clock, he explained. > Morgan said when the generation was turned down, electric clocks that > were plugged into the wall - alarm clocks, stove clocks, microwave > clocks - all slowed down. The change was quite slow and unnoticeable > until several minutes had been lost over a few days, he said. > > ----------- > > Or do y'all think I am misinterpreting the story? Easier to believe > that the synchronous clock went bad than the GPS clock. > > On a related note, I visited a remote navy base once and went to talk > to the folks running the station power plant, which was comprised of > 24 very large diesel generators. They had a $2 synchronous clock > sitting next to a $2 battery operated quartz wall clock, and were > manually controlling the frequency. I suggested that they at least > get a high quality quartz clock, if not a GPS based clock for the > reference...but that costs money, so they weren't planning to change. > > Also related, I have an Electro Industries frequency meter that I use > to monitor the power line here in Rhode Island. I have never seen it > vary more than .05 Hz from nominal (59.95 to 60.05). On the other > hand, during a trip to Scotland, the power frequency went fully 0.5 > Hz out, from 49.50 - 50.50, Hz while I was there. > > In both cases, the average is right on over the course of several days. > > Tom Frank, KA2CDK > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
