[time-nuts] Yukon Energy causes time sync problems

[Thomas A. Frank]

On Apr 10, 2010, at 2:17 AM, Bill Hawkins wrote:

> Read the quote again, please.

I did, which is why I am a bit confused.

> 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.

Which is exactly as it should be.  It reads to me like their line  
clock malfunctioned and was running fast *when it had no cause to*,  
so they responded as expected (slow the generators), with the  
expected result (everyones clocks slowed down).

> The satellite clock was slow.

Yet my takeaway from the article was not that the satellite clock was  
in error, but that the line clock was.  It was running fast when it  
shouldn't have.

I can see where a line clock would run fast when it shouldn't, but I  
can't see where a GPS clock would run slow...

Tom Frank, KA2CDK
BSEE RPI 1985




>
> 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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