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

[john.haine at haine-online.net]

See this web page:

https://www.nationalgrideso.com/data-portal/system-frequency-data

for 1s resolution stats for the UK.  As much data as you could possibly want!  Here's another site that also tracks Europe - lots of cross-border power links. 

https://gridradar.net/en/mains-frequency

Grid locking is another thing that could be disrupted by GNSS outage.

-----Original Message-----
From: Bob Camp via time-nuts <time-nuts at lists.febo.com> 
Sent: Friday, March 22, 2024 5:05 PM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Cc: Bob Camp <kb8tq at n1k.org>
Subject: [time-nuts] Re: Power line timing -- setting a clock

Hi

Back in the 1960’s what you describe is pretty much “how it was done”. We figured out that the local power company “lined things up” between 4 and 5PM each day. Tune into WWV and you could watch them bring your wall clock (hooked to AC power) into line with WWV. Indeed seconds / ten’s of seconds sort of corrections occurred. We suspected there must be a reason. One of the gang went on a tour of the power plant and asked them why? The answer turned out to be that they connected back up to the grid at 5 PM. Mid day, they generated the power locally. Just like us, they had a radio that listened to WWV.

These days, if you are hooked to one of the grids, drifting seconds is pretty unusual. Everybody needs to stay “in phase” and that (since the  late 1980’s) usually goes back to GPS (at least in the US and Canada). If you are “off grid” then I suspect you are right back to the 1960’s approach, at least in some cases. 

Do the corrections get logged? I suspect they do indeed get documented in some way. It could easily be a paper form sitting in an office somewhere. Find out the phone number for that office and you probably could get the after the fact info. There also does need to be a “how many microseconds of phase shift” sort of number. It would be specific to this or that source feeding the grid. Without that, you would have a very hard time controlling things. No idea how to get at that number or if it actually would be of any use. 

Bob

> On Mar 21, 2024, at 6:13 AM, Hal Murray via time-nuts <time-nuts at lists.febo.com> 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.
> 
> 
> --
> These are my opinions.  I hate spam.
> 
> 
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