[time-nuts] Yukon Energy causes time sync problems
bill at iaxs.net
Sat Apr 10 02:17:05 EDT 2010
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.
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
> uses a standard wall clock to display it. It is the reference clock
> slowed down when it should have failed to work at all. Perhaps the
> (maybe it was really a HP 113) needed oil. There's the real
> question for
> 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
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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