[time-nuts] Re: Power line timing -- setting a clock

[mcleannb at bigpond.com]

When I worked in the oil and gas industry our plant control room had 2 clocks; one ran on mains AC the other was a fairly accurate quartz clock that looked identical. The were quite often out during the working day but the night shift operator tried to have the AC clock accurate in the hour before day shift start. Trying to get the workforce to work on time.

-----Original Message-----
From: Peter Reilley via time-nuts <time-nuts at lists.febo.com> 
Sent: Saturday, March 23, 2024 10:53 AM
To: Hal Murray via time-nuts <time-nuts at lists.febo.com>
Cc: Peter Reilley <preilley_454 at comcast.net>
Subject: [time-nuts] Re: Power line timing -- setting a clock

Back in the 1970's I installed Westinghouse power plants in the US and around the world.   On the control panel there was a sort of clock that showed the difference between the AC produced by the plant and some reference, could be WWV or a crystal, I don't remember.

The "clock" had only one pointer and would advance clockwise if the plant was running fast and it would move counter-clockwise if the plant was running slow.   If the pointer went around more than one turn then you did not really know where you were.

In the US the clocks were not used because the frequency was determined by the regional dispatcher.

Overseas the clocks were ignored by the operators because no one used AC driven clocks.   People were just happy to have power and did not care about the frequency.   If the voltage was reasonably close the the frequency was more or less correct that was much better than the alternative, no power.


On 3/21/2024 6:13 AM, Hal Murray via time-nuts wrote:
> All sorts of gear uses the power line to drive their clock.
>
> I picture that a corner of the control room has 2 clocks, one tracking 
> UTC and the other tracking the power grid.  The difference between 
> that pair feeds into their complicated control system that includes 
> some sort of PLL that keeps the power line clock tracking UTC.
>
> Is there any way to get a copy of their power line clock?  So I can 
> set my power line clocks to a similar offset so they will have a 
> better chance of being right tomorrow after they correct for today's 
> offset?  I'm not looking for microseconds, just microwave-setting accuracy.
>
> Do they have a graph showing the offset for the last week or month?  I 
> can line that up with my graphs.
>
>
>
> Here is a graph from Feb/Mar 2024 where it drifted a minute over 2 weeks.
>    https://www.glypnod.com/TimeNuts/60Hz/60Hz-2024-FebMar.png
> That's 4 seconds per day.
>
>
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