[GreenKeys] Frequency deviations in Continental Europe including impact on electric clocks steered by frequency

[Martin]

In the UK, as I understand it the frequency still varies as it has 
always done, ie about 10 seconds around GMT. The grid is of course all 
synchronised but the grid as a whole will vary the speed of the 
generators to adjust for load, but the time variation USED to be always 
set back to correct by speeding up when convenient so that the variation 
used to always be correct around the mean time. So some parts of the day 
it may be 10 seconds slow, but at night it likely be 10 seconds fast. 
Now that few people use the frequency to actually keep time it may not 
be as accurately maintained, not sure, but the deviation will always be 
within bounds.

Many electric frequency clocks still function, especially in public 
clocks. Many of course have been replaced by radio clocks synchronised 
to either the UK or the German standard frequency transmissions on 60 
Khz. Few public buildings run any kind of centrally synchronised systems 
anymore, its very expensive. Its cheaper to throw up a few radio clocks 
but replacing batteries then becomes the problem! I maintain one of the 
last Gent pulse clock systems in the UK, in the Exam schools in Oxford. 
Unless anyone can challenge me! The problem with all pendulum clocks, 
even electrically driven ones,  is that you will find it hard to get 
better than 1 second per day accuracy unless its in a controlled 
environment. Some more modern pulse systems used quartz clocks to 
generate the pulses but they be all gone now too. Some radio controlled 
versions of master clocks were devised but they tend to only be used in 
continental europe. A few big ones get over into the UK as single public 
dials but their life is short.


Martin

On 06/03/2018 15:36, Richard Knoppow wrote:

>    In the past the generators were slightly speeded up or slowed down 
> but I am not sure if they can do that now because of the "grid". Power 
> from different sources must match in phase requiring rather close 
> control of frequency. In the old days when a generator was brought on 
> line its output had to be brought into phase with the other machines. 
> Speed is not the only method of controlling load variations, all these 
> machines have separate exciters so the amount of excitation can be 
> varied to change the output.
>     I also don't know how school or factory master clocks work now but 
> at one time they were pulse operated with the pulses generated from a 
> central source. I also have seen these catch up or slow down by a 
> little but I don't know how they handle daylight saving time. I was an 
> election clerk recently were we were set up in a school. We had just 
> come off daylight saving time. The clocks were off by an hour when we 
> arrived to set up in the early morning but by about mid day they were 
> back on. I think they may just have shut them down for a hour.
>     I wonder how many remember the old Western Union clocks, once in 
> every radio station? These ran on a governed DC motor with a local 
> battery. Once an hour a pulse was delivered over a wire line which 
> would set the clock exactly on the hour. The service from Western 
> Union cost something like a dollar a month or maybe it was a dollar 
> per week. The clocks were made for WU by the Self-Winding Clock 
> Company. In radio stations they were usually in square wooden cases to 
> muffle any noise they made. I think the railroads also used these. 
> There were also Postal Telegraph clocks but these were just regular 
> synchronous clocks referenced to the power line.
>    In the Los Angeles area until about 1950 some suburban areas had 
> 50Hz power while the city was 60Hz so one could find electric clocks 
> for both for sale. Burbank had 50Hz power so Warner Brothers had 
> rotary converters for frequency changing to operate the synchronous 
> motors in their RCA sound equipment. At some point around 1950 
> Southern California Edison and the smaller companies like Burbank 
> Light and Power got on the grid with the LADWP and changed to 60Hz. 
> Everyone with electric clocks had to change them.
>
> On 3/6/2018 7:09 AM, Bob kb8tq wrote:
>> Hi
>>
>> Most schools / factories / train systems, even back in the 1950’s ran 
>> on a “master clock”
>> system rather than a bunch of independent clocks. The issue was not 
>> so much line
>> frequency as a power outage. Going around to a bazillion clocks to 
>> re-set them all to the
>> correct time cost a lot of money.
>>
>> Back when I was in school (yes school had been invented that far 
>> back) the ham radio club
>> guys noticed that WWV and the wall clock had an interesting 
>> relationship. The wall clock
>> drifted during the day and between 4 and 5 pm went faster (or I 
>> suppose slower) to eventually
>> match up with WWV by 5 pm. The largest deviation that I recall seeing 
>> was around 30 seconds.
>>
>> Bob
>
>

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