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

[Larry McDavid]

I believe the local electric generation utilities have largely divested 
themselves of maintaining an accurate 60 Hz mains frequency, both 
instantaneously and total cycles per day.

I know that my home clocks that count cycles from the power lines no 
longer show accurate time. In fact, compared to GPS time, I often see 
more than 5 seconds error in just a week's time, here in Southern 
California.

If I don't reset those power-line (no crystal reference) clocks, I've 
surely seen errors of 30 seconds accumulate. That holds true for 
stand-alone power-line clocks and the clocks in microwave ovens and 
kitchen appliances. But, all those clocks in appliances roll the minute 
digit about simultaneously, when the time had been set accurately to the 
second. This indicates the various appliance clocks are counting cycles 
accurately, but the cycle count per day varies and is not well maintained.

All those appliances loose the time setting when there is a power 
failure. It is probably mild OCD, but I try to set all those clocks 
using a GPS clock and to the second. I used to rely on a mains-frequency 
clock for A/V timing but now I use a GPS Clock by Nick Sayer, sold on 
Tindie; it displays time to tenth-second. This GPS time is closely 
tracked by my Heathkit WWV (not WWVB) Most Accurate Clock; a few days 
after carefully setting a mains frequency appliance clock, the time is 
very typically seconds off GPS time.

-Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)

On 3/21/2024 3:13 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.
> 
>