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

[Larry McDavid]

I don't immediately find the reference now, but my recollection is that 
there was relaxation in the requirement to maintain accurate mains 
frequency a few years ago. About that time, I began to notice my 
mains-synched digital clocks began to not keep accurate time.

All I can tell you with good confidence is that my home digital clocks 
that are synched to the mains no longer keep accurate time here where I 
live in Anaheim. And, I am very confident all those appliance clocks 
still roll the displayed minute simultaneously when I have set them 
accurately as I usually do. I am confident these clocks are counting 
cycles correctly. I watch time carefully as TimeNuts do!

However, Anaheim may be an unusual or perhaps a special case as the City 
of Anaheim is my electric utility provider. The city owns the power line 
distribution system, buys power at a wholesale level and sells it 
directly to city residents. Our electric utility does not follow the 
rules or pricing structure our nearby public electric utility does. For 
example, Anaheim has only a the usual baseline price per kWh and then 
one--and only one--rate change after that for residential users. The 
public electric utility stair-steps the rate at least four times.

Further, Anaheim owns, and operates within the city, seven large natural 
gas-fired turbine peaking generators; these fill at least a 4 city 
blocks square area. My electric energy cost is always a bit lower than 
that of surrounding cities.

Does that have any relevance to this time-keeping by mains frequency 
issue? I have no idea. When I want accurate time, I use my GPS clocks. 
But, it is annoying to always see my appliance and desk clocks display a 
time different than by GPS. Truly, I have seen these mains-synched 
clocks as much as 20 seconds off GPS time; on a short-term basis, the 
displayed time might be slow (the usual case) or fast.

Anaheim owns part of the Four Corners power generation system and used 
to own part of the San Onofre nuclear station (now being disassembled). 
I believe much of the major intertie network is actually dc, so 
frequency is not a consideration in that case.

Both my Heathkit WWV GC-1000 (in HI SPEC) clocks and my Geppetto GPS 
clocks display time to tenth-seconds. I have one set of these clocks 
side-by-side and the seconds digits roll together within less than a 
tenth-second by slow motion video.

"Youse guys" can quote regs about maintaining mains for clock accuracy, 
but it is not working here. Anaheim is the largest city in Orange 
County, California, with a population of some 340,000+. Remember 
Disneyland? Yep, here in Anaheim.

Best wishes,

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

On 3/24/2024 7:42 AM, Peter Reilley via time-nuts wrote:
> There are a few things to consider here.   First is that California is 
> part of the western grid.
> The western grid is certainly not out by more than a few seconds at most 
> at any particular
> time but it will always make up the slippage to restore the correct 
> time. Â  Clocks on the
> grid will be correct on average.   There are web sites that track this.
> 
> Your particular case:
> 1)Â Â  At times a section of the grid may break away from the western grid 
> because of equipment
> failure. Â  During this time the local grid will be working to restore 
> the local grid stability.
> They wont worry about maintaining the correct time. Â  Eventually they 
> will reconnect to
> the western grid. Â  You may not notice this.
> 
> 2)Â Â  Your local circuit will have circuit breakers at substations. A 
> fault on your local circuit,
> like a tree branch touching the line, will cause the breaker to open. 
> Many breakers have
> an auto-close feature. Â  After a certain time, generally just a few 60 
> Hz cycles, they will
> re-close automatically.   They will repeat this a certain number of 
> times and then remain
> open.   You may notice this as the lights flickering.   During this time 
> you will loose
> a few cycles.   A non auto-close breaker will stay open until an 
> operator manually closes
> it.
> 
> There are probably a few other scenarios where a section of the grid may 
> loose correct
> time keeping but the main grid will always strive to be correct on average.
> 
...