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Old 9th Mar 2018, 6:19 pm   #81
Nickthedentist
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Default Re: Electric clocks running slow warning

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Originally Posted by G6Tanuki View Post
Kitchen clock [old-style one with hands] is quartz-controlled and only needs setting every year when I replace its AA battery... Not depending on mains frequency makes life so much easier.
But that's precisely why I like synchronous clocks - no battery to change, they just run and run.
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Old 9th Mar 2018, 6:30 pm   #82
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Default Re: Electric clocks running slow warning

But they need resetting after any power-outages, which here are much-more-frequent than a once-per-year battery replacement.

I guess if you live in a town/city where the mains has 99.9999% reliability a mains-synced clock makes sense: us rural-types don't have that luxury.
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Old 9th Mar 2018, 8:52 pm   #83
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Default Re: Electric clocks running slow warning

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For some reason VCRs and other video recorders have never used synchronous clocks.
Philips N1500?
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Old 9th Mar 2018, 10:46 pm   #84
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Default Re: Electric clocks running slow warning

The 1940's Smiths synchronous alarm clock in the bedroom keeps perfect time. When I need an accurate time check downstairs, the Icecrypt STB that feeds the kitchen TV displays the time when it is in standby. I guess it must get it from one of the digital multiplexes akin to how many VCRs used to get their clocks synchronised from the information on the old analogue teletext.
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Old 10th Mar 2018, 2:11 am   #85
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Default Re: Electric clocks running slow warning

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Originally Posted by paulsherwin View Post
Mains clock radios (and other mains equipment with clocks) traditionally used the mains frequency as a reference. I don't know if this is still the case or if they all use quartz now.

For some reason VCRs and other video recorders have never used synchronous clocks.
On the continent, some cheap imported LED clocks and clock radios still use mains sync. Philips switched to switch mode wall warts so those are probably crystall controlled nowadays.

Also, I'm pretty sure first generation VHS and betamax recorders actually used mains synced clocks. Philips VCR recorders certainly did, the earliest ones even with a motor driven timer clock.
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Old 10th Mar 2018, 8:44 am   #86
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Default Re: Electric clocks running slow warning

I will have to check whether my (Sanyo) Betamax machine probably uses mains synch for its clock. I know my old VHS machine and (pre-digital DVD recorder) used the TDSP (Television Data Service Packet?) broadcast alongside Teletext - and promptly ceased to keep correct time once analogue televsion was switched off.

I replaced both of these with a (Daewoo) combined VHS/DVD recorder that somehow manages to keep correct time, even though it doesn't it doesn't have a DTV tuner.
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Old 10th Mar 2018, 9:30 am   #87
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Default Re: Electric clocks running slow warning

I'm surprised that National Grid haven't yet corrected the discrepancy in the mean frequency, leaving our synchronous clocks 1-2 minutes slow. Does anyone know whether we now have a permanent error which will remain, meaning I should go round resetting our clocks, or will the Grid gradually correct them?

Martin
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Old 10th Mar 2018, 10:32 am   #88
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Default Re: Electric clocks running slow warning

My Solar inverter has been showing a frequency slightly higher than 50Hz (only by a few hundreths of a Hz) but I don't know how good the calibration is in it; perhaps it's a bit optimistic. Of course, it's only measuring during daylight, so no help if the slowdown is happening at night .....

EDIT: If anyone reports a self-correction over the next few days, I'll check my own readings and they should be higher than recently.
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Old 10th Mar 2018, 10:54 am   #89
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Default Re: Electric clocks running slow warning

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I'm surprised that National Grid haven't yet corrected the discrepancy in the mean frequency, leaving our synchronous clocks 1-2 minutes slow. Does anyone know whether we now have a permanent error which will remain, meaning I should go round resetting our clocks, or will the Grid gradually correct them?
Doubt it will be corrected now.

The requirement is to retain 50Hz averaged over a 24 hour 'window' so any correction to a frequency error has to be made during that time. If it wasn't, it's too late - because, doing a correction now, for instance, would give a frequency error in THIS 24 hour window.

I wouldn't like to think I was commissioning a synchronous clock today, but might have to adjust it in a few days' time!

However, if National Grid have missed some cycles, I'd expect them to announce their error. I am surprised there's no legal obligation for them to do so - or is there?
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Old 10th Mar 2018, 11:06 am   #90
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Default Re: Electric clocks running slow warning

Is it possible that those who have observed synchronous clocks to be slow, and the discrepancy NOT made up, have in fact suffered a very brief power cut ?
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Old 10th Mar 2018, 11:29 am   #91
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Default Re: Electric clocks running slow warning

Unlikely because, unlike synchronous timeswitches, my clocks are not self-starting and would just have stopped at the time of the supply interruption.

Martin
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Old 10th Mar 2018, 11:57 am   #92
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Default Re: Electric clocks running slow warning

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However, if National Grid have missed some cycles, I'd expect them to announce their error. I am surprised there's no legal obligation for them to do so - or is there?
I expect there will be internal procedures for reporting, but there may not be a requirement to make a public announcement. Even if there were, most journalists wouldn't see it as significant, so it wouldn't be widely reported in the media apart from the trade press.
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Old 12th Mar 2018, 6:10 pm   #93
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Default Mains frequency time error again!

It is only nine months since this was discussed lastly when all my synchronous clocks ended up 2 mins slow! Well, it has happened again, everything has been 2 mins slow for the last week or so.
Therefore, are only other synchronous clock owners here running slow, or did the Isle of Wight, leave the grid and do it's own thing?
Thanks
R

National Grid stats all look ok over the last month, but I know over parts of Europe they are up to 6 mins slow.
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Old 12th Mar 2018, 6:31 pm   #94
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Default Re: Electric clocks running slow warning

It's a national problem, and there's no sign of the Grid correcting it.

According to press articles, Continental Europe has an even more serious error of 6 minutes and some newspapers are blaming that for the UK error. That doesn't make sense because the UK Grid is separate. Cross-channel links are HVDC.

Martin
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Old 12th Mar 2018, 8:11 pm   #95
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Default Re: Electric clocks running slow warning

What I fail to understand, is why is this not corrected ? in either the UK or in mainland Europe.
I can see that low frequency may be unavoidable at times of exceptional electricity demand or in case of generating plant breakdowns etc.
But demand drops at night and margins are ample, so why is not the frequency very slightly increased at night in order to compensate for losses in the day.

It is an observed fact that maximum UK demand for electricity is about 50GW, and that is met, though perhaps with an undesirably small margin.
It may also be observed that overnight demand drops to about 30GW, so no trouble in regaining earlier losses.
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Old 12th Mar 2018, 8:21 pm   #96
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Default Re: Electric clocks running slow warning

If National Grid paid the generators to push the frequency higher for long-enough to 'correct' the network's historic sloth, they'd just be creating a new problem of a minute [pun intended] number of geekish people complaining that the old clocks they'd set a month ago were now running several-minutes fast!

For the vast majority of UK residents - whose timing does not depend on mains-frequency - it's a total non-issue.
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Old 12th Mar 2018, 9:28 pm   #97
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Default Re: Electric clocks running slow warning

Looking at 'gridwatch' right now

UK consumption is 43.5GW, right on the edge of the orange band on the scale, which is pretty heavy consumption.

Nuclear is runnng its usual 6.67GW Combined cycle gas is at21.17GW, close to its max of 25GW and they've got coal cranked up to 8.41 GW which means they're geting tight on low carbon sources. Not desperate enough to light up the plain old gas turbines yet.

So I'd expect the frequency to be trailing a bit, but no, 50.072Hz.

Is someone playing catch-up?

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Old 12th Mar 2018, 10:23 pm   #98
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Default Re: Electric clocks running slow warning

Interesting, I hope they continue to 'catch-up' for sometime yet, as I am still -2 mins, and reluctant to change my array of mains clocks just yet, so will wait and see where we are at the end of the month when the enforced BST change is due.
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Old 12th Mar 2018, 11:10 pm   #99
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Default Re: Electric clocks running slow warning

It looks like the Grid has quietly dropped its previous responsibility to keep the mean frequency at 50Hz over a 24 hour period.

I don't know how many synchronous clocks are still in use, but I guess they're a dying breed. The Grid is presumably relying on that to take their relaxed attitude.

Still a puzzle that there's an implication that it's somehow connected with the Continental frequency problems. Fake news maybe?

Martin
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Old 12th Mar 2018, 11:53 pm   #100
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Default Re: Electric clocks running slow warning

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Originally Posted by emeritus View Post
akin to how many VCRs used to get their clocks synchronised from the information on the old analogue teletext.
Teletext is digital, never analogue. it was a digital service added to an analogue transmission. It still exists elsewhere in Europe added to their digital transmissions.
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