[time-nuts] Yukon Energy causes time sync problems

Bob Camp lists at rtty.us
Sat Apr 10 08:49:51 EDT 2010


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
> 
> 
> 
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