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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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#181 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Wind ans solar are the culprits for drift.
They just generate a reconstituted sine wave from DC using a 10khz clock. You can hear the 10khz clocked transformer "buzzing" when you walk past a field of solar panels while the sun is shining. I have heard reports that wind turbines make the same noise. |
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#182 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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That is not why frequency drift occurs. It is the relatively uncontrollable MW which are the problem. All generators on the grid at a given time generate exactly the same frequency (however they do it), otherwise things go bang.
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#183 |
Tetrode
Join Date: Nov 2017
Location: East Lothian, Scotland, UK.
Posts: 66
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The demand profile is always leading the generation profile which creates the frequency deviations. "Modulation" is still done, but only by those generators who have the ability (CCGT, Hydro, OCGT, coal etc). Electricity is "sold" into the grid via BETTA (British Electricity Trading Transmission Arrangements). Prior to 2005 this was done under NETA (New Energy Trading Arrangements). The energy itself is governed by the Grid Code, which is a fun read. There is no requirement, legal or otherwise for generators to "catch up" or "slow down". Yes, decades ago when nationalised, all stations had master clocks which enabled the stations to correct, but that was long ago and before the energy trading and grid codes were adopted for the privatised industry.
https://www.nationalgrid.com/sites/d...rid%20Code.pdf |
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#184 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,337
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My mains electric clock, which I adjusted to BST, is presently keeping perfect time by the pips (as heard on FM).
In view of the present-day concern about security, when I was with GEC I was interested to find in our office some copies of a journal about nuclear power generation, published in the 1960's, each issue of which featured a different nuclear power station, accompanied by a multi-layer coloured isometric drawing of the power station, with different layers printed on different transparent sheets which you could peel away layer by layer to see exactly what was inside and where it was in three dimensions. Last edited by emeritus; 4th Apr 2018 at 5:15 pm. |
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#185 |
Dekatron
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,079
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I've just reset my Philips digital radio alarm clock (which I'm 99% sure uses mains as a frequency reference).
Later this year I hope to have a Goblin Time Spot running, which definitely does. |
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#186 | |
Tetrode
Join Date: Nov 2017
Location: East Lothian, Scotland, UK.
Posts: 66
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![]() Quote:
http://econtent.unm.edu/cdm/search/c.../subjec/ad/asc |
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#187 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 901
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Local distribution network voltage waveform distortion may have some interaction with certain vintage digital clocks. I recall that houses nearby telephone exchanges back in the 70-80's have complained about clock inaccuracy - the large 6-pulse scr phase reg battery chargers were known to cause voltage waveform glitches that could cause additional zero crossings.
Nowadays there may be the chance of local interaction with PV inverters that use a common technique for anti-islanding whereby part of the voltage waveform is left 'unfilled', and if the grid doesn't cause a suitable response during that short duration then that is a mechanism for ascertaining that the grid is lost and hence to disconnect. That waveform disturbance can be an issue for other equipment, and for the PV inverters themselves if the local grid impedance is high enough. |
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#188 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,996
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It seems that Europe have been doing some catching-up:
https://arstechnica.com/tech-policy/...o-oven-clocks/ |
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#189 | |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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I seem to recall some of my colleagues fuming about the new grid code because it appeared to have much more economic/commercial input into its writing than EE input. The early versions led to much game-playing by the generators, even though the government seemed surprised by this. Who would have thought that newly-formed commercial enterprises would seek to maximise profit rather than deliver reliable power? |
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#190 |
Tetrode
Join Date: Nov 2017
Location: East Lothian, Scotland, UK.
Posts: 66
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Yes, I remember some of the games that were played, including the time that the generators were nearly paid at £0/MWH as they had all bid into the pool at £0 to ensure they generated. I was reasonably insulated from most of the shenanigans as I worked for a nuclear generator, although even then there was the occasional try on.
Last edited by tealandsilver; 9th Apr 2018 at 9:07 pm. Reason: Correction to post |
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#191 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Yes, I heard that free power appeared from time to time. The opposite trick was to (commercially) withdraw plant which was actually (technically) available so that the price shot up and then maybe you could get paid extra for bringing it back in as an emergency. It is an example of the general idea that people maximise whatever they get rewarded for maximising, even when this is not what is intended to happen.
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#192 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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I've just restored a 1934 synchronous clock and it's been on soak test for a few days. Remembering this thread, I kept an eye on the clock's second hand, and late last night it was running five seconds behind. This morning, it was just three seconds behind, and now it has caught up completely. Fascinating.
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Phil Optimist [n]: One who is not in possession of the full facts |
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#193 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,843
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That's good to know. Normal service has been restored on my old clocks too, thank goodness.
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#194 |
Octode
Join Date: Jun 2011
Location: West Midlands, UK.
Posts: 1,571
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I wondered what was up with some of my digital clocks earlier this year so this thread has been illuminating. I still have the electric clock that sat on the mantelpiece in the front ('best') room of my parents' house and pre-dates me by a good number of years I'm sure. We had other clocks but 'the electric' was the gold standard in our house and the one we always knew to be 'correct' (what little did we know!).
Recently, given the mains frequency issues, the ever-reliable quartz kitchen clock has been the one to check. The only time it is touched is when the hour changes. However, it did fail a month ago. A quick inspection of the slightly leaky AA battery confirmed the likely problem. Bearing in mind a recent thread about battery life I checked the 'best before' date: June 2011. |
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#195 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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I'm pleased that this thread, like many old clocks, is still going! I set my latest acquisition, a Ferranti model 7 alarm clock with sweep seconds hand, running at exactly GMT the night the clocks changed (October 27th) and since then I have monitored twice daily how far it deviates from 'correct' time, as displayed on a radio-controlled digital clock. The results are quite surprising.
For the first day, the synchronous clock ran a few seconds slow, but for the rest of the first week it ran fast, increasing from just 2 seconds fast on the 29th to a peak of 40 seconds fast on November 3rd. Then something seems to have happened, and the grid slowed down overnight to the point where the clock was just 4 seconds fast on the morning of the 4th, and spot-on again just after midnight on the 5th. Since then it has deviated a few seconds both fast and slow, but as I write it is just one second slow. This is probably nothing more than random variation, but it is tempting to think that some control is still being exercised. I'll keep checking twice daily. It is also reasonable to expect that anyone doing the same exercise anywhere in the UK would see the same results.
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Phil Optimist [n]: One who is not in possession of the full facts |
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#196 |
Hexode
Join Date: Oct 2016
Location: Newport, South Wales, UK.
Posts: 278
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Interesting observations Phil. I'm imagining there might be one or two 'old school' staff left at the National Grid who notice these things and make corrections (within the limits allowed) when they are on duty. Then things drift again when they have their rest days.
I wish I had a suitable clock! |
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#197 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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Coincidentally, a letter has just appeared in the December 2018 issue of ‘Engineering and Technology’, the members’ journal of the IET which was previously better known as the Institution of Electrical Engineers, from a chap who works for the company that “supplies the frequency measuring and display system used in the National Grid Control Rooms”. By all accounts, the discrepancy between ‘grid time’ and ‘atomic time’ is indeed still being monitored and managed. The writer states: “Even in the late 1990s it was uncommon for that to deviate by more than five seconds and it changed very slowly. Today, 30-second deviations and a faster rate of change is much more the norm. We have even seen deviation figures of 45 seconds occasionally.”
The key words in this letter are, and I quote, “Yes, the system time is still managed by the Grid to keep mains-driven synchronous electric clocks accurate.”
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Phil Optimist [n]: One who is not in possession of the full facts |
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#198 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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The loading on the base load stations must be a bit more variable now that we have solar and wind on line.
This could be checked by looking at the weather and checking the gridwatch website. |
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#199 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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Agreed, that’s what’s causing the greater and more frequent instantaneous frequency deviation, but we’ve been discussing whether or not National Grid has abandoned the medium and long-term control of the actual number of cycles generated on a daily, weekly or annual basis. It appears this is still being done, but maybe the discrepancy is being allowed to widen.
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Phil Optimist [n]: One who is not in possession of the full facts |
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#200 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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It is the answer to a potential question that may well get asked at any time.
Now we can just say go to post #199 for the answer. |
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