8th Mar 2018, 9:32 pm | #61 | |
Heptode
Join Date: Aug 2009
Location: High Wycombe, Bucks. UK.
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Re: Electric clocks running slow warning
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At that time, there wasn't any severe weather, as far as I can remember. Now my synchronous clocks have gone slow by about 2.5 minutes. I think this started happening just before the big freeze and snowstorms, so perhaps the weather isn't the only contributing factor. I'm hoping the clocks will be corrected like they were last year. My nixie tube clock lost power altogether last week, so I've had to reset it. It's been fairly stable since then and is now showing the correct time. That means it might end up being too fast, but I'll have to reset it again at the end of March anyway so it doesn't matter much at the moment. |
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8th Mar 2018, 11:19 pm | #62 |
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Re: Electric clocks running slow warning
There is a clock specialist in the USA that sells low power mains inverters about 6W capable as I recall, with a crystal as the time base. They are used to power mains synchronous clocks so they are accurate, as the mains frequency, increasingly is not. A small inverter like this not difficult to make, most vintage motor operated synchronous clocks consume 3W or less, sometimes more if they have a dial lamp.
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9th Mar 2018, 9:40 am | #63 |
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Re: Electric clocks running slow warning
Forgive my ignorance, but.. what's the problem? Electric clocks are not meant to be accurate. I've never had an electric clock that didn't need to be adjusted at least once a month.
The only accurate clocks I know are either mechanical clocks or Internet connected ones. |
9th Mar 2018, 9:52 am | #64 | |
Dekatron
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Location: Penrith, Cumbria, UK.
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Re: Electric clocks running slow warning
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Any lag during peak loading was meant to be compensated for during light loading. But, as has been pointed out, the generating system is not what it once was with the likes of wind turbine contribution; solar; feed-in, etc... It may be when the latest generation of 'peaker' plants gets going to fill in the shortfall the accuracy will improve.
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9th Mar 2018, 10:31 am | #65 | |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
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Re: Electric clocks running slow warning
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The most accurate readily available clocks nowadays are radio-controlled. I have two sitting in front of me here: one receiving MSF 'Rugby' 60kHz (now at Anthorn) and the other its German equivalent DCF77, 77.5 kHz, near Frankfurt. Unsurprisingly, both read exactly the same time to the second. The Smiths synchronous clock on the wall on the other hand currently lags by approx 1 min 30 seconds, whereas it was pretty well correct in January. Something has deteriorated in the long-term grid frequency stability system and it would be interesting to get the facts. Martin
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9th Mar 2018, 10:44 am | #66 | |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
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Re: Electric clocks running slow warning
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I used to rely on mine unquestioningly for all those things that have to be done on-time (catching the bus into town, school pick-up etc.) but now there's an annoying discrepancy between real time and what's displayed. EDIT: crossed with Martin. |
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9th Mar 2018, 11:03 am | #67 |
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,052
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Re: Electric clocks running slow warning
“Time is an illusion. Lunchtime doubly so.”
(Douglas Adams, The Hitch-hiker's Guide to the Galaxy) |
9th Mar 2018, 12:23 pm | #68 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
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Re: Electric clocks running slow warning
I get the impression that solar and wind stations do not help with frequency correction.
They have a 10Khz inverter that may well be able to correct for rectifier loads to some extent but I doubt they will be able to help with frequency as they will just track and synch with what is present at the the point where they are connected to the grid. Technology is advancing quickly mainly with the power per area of panels. This can sometimes conflict with the time it takes to get planning permission. We locally have had an installation go in where the original panels were NLA so they just substituted ones that looked externally the same. When the sun finally came out the 11KV drop cable blew up leaving a carbon footprint on the pole. Most solar installations are owned by private companies and there is not yet a standard for frequency correction signals to be sent to them. If you stand close to a field of solar panels the green boxes sound like giant 405 line TV sets. |
9th Mar 2018, 12:40 pm | #69 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Electric clocks running slow warning
Power stations which are able to modulate (and have owners willing to modulate) are sent a frequency setpoint from grid control. They then adjust their output accordingly, using an agreed slope. Everyone else just generates whatever power they want to or have been asked to. All generators generate exactly the same frequency.
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9th Mar 2018, 1:17 pm | #70 |
Hexode
Join Date: Oct 2016
Location: Newport, South Wales, UK.
Posts: 278
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Re: Electric clocks running slow warning
An academic paper on 'Impacts of Power Grid Frequency Deviation on Time Error of Synchronous Electric Clock and Worldwide Power System Practices on Time Error Correction' published by
http://www.mdpi.com/1996-1073/10/9/1283/pdf Based on data from sensors all over the world gathered in 2016, the authors found that Time Error Correction is practised in North America, Western Europe (including the UK), Japan and Australia but not most other countries monitored. I have found nothing in National Grid documentation available online so perhaps it has been quietly dropped here? I don't know. |
9th Mar 2018, 1:56 pm | #71 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
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Re: Electric clocks running slow warning
Sad if it has, but can anyone think of any modern equipment where lack of long-term mains frequency stability is of any consequence?
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9th Mar 2018, 2:10 pm | #72 |
Dekatron
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Location: Charmouth, Dorset, UK.
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Re: Electric clocks running slow warning
This sort of thing regularly happened in the '50's but I seem to remember that they slightly increased the frequency when the load was off in order to maintain the accuracy of synchronous clocks and timers.
Peter |
9th Mar 2018, 2:15 pm | #73 | |
Moderator
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Location: Oxford, UK
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Re: Electric clocks running slow warning
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For some reason VCRs and other video recorders have never used synchronous clocks. |
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9th Mar 2018, 3:36 pm | #74 | ||
Nonode
Join Date: Mar 2010
Location: Dukinfield, Cheshire, UK.
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Re: Electric clocks running slow warning
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That's only roughly remembered, I haven't looked it up.
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9th Mar 2018, 3:38 pm | #75 | |
Octode
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Location: Hebden Bridge, West Yorkshire, UK.
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Re: Electric clocks running slow warning
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9th Mar 2018, 3:55 pm | #76 | |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,130
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Re: Electric clocks running slow warning
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Far less reliance is placed on mains frequency these days due to the amount of international trade. A clock radio for example might be sold worldwide, and therefore must work accurately even in countries with poor frequency control. Cheaper to make them all with quartz based timekeeping rather than different versions for different markets. Until recently, low frequency was a serious matter for large factories and even for the nation as a whole. Frequency 0.5% low meant that production was slowed by about that amount, but wages, rates, interest on invested capital, insurance and many other costs remained unaltered. This could have a measurable affect on profit. These days we have less manufacturing, and what we do have tends to use variable speed drives set to the needs of the process, and not locked to line frequency. |
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9th Mar 2018, 4:15 pm | #77 |
Dekatron
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Location: Lynton, N. Devon, UK.
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Re: Electric clocks running slow warning
My clock radio (Philips, about 12 years old) has battery back-up, but the timekeeping is appalling! Whereas on mains, it's excellent. So I deduce that mains frequency is used normally, and if mains dies a simple RC relaxation oscillator is used as a clock reference.
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9th Mar 2018, 4:46 pm | #78 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Electric clocks running slow warning
The only mains-frequency-dependent clock I have here is the central-heating programmer: and as I noted in another thread recently I don't actually use it.
The computers, routers, switches and the CCTV recorder use NTP to sync to a Stratum-1 time server. 20-year-old Sony bedside clock-radio uses RDS-time, as does the Sony radio/CD in the car. Kitchen clock [old-style one with hands] is quartz-controlled and only needs setting every year when I replace its AA battery. Shack clock is DCF-locked; my indoor/outdoor weather-station likewise. My phone either picks up its time from the network or uses GPS-derived time. Several times a year I have to run the house from a generator. They're not famous for their frequency-accuracy! Not depending on mains frequency makes life so much easier. |
9th Mar 2018, 5:24 pm | #79 |
Heptode
Join Date: Apr 2003
Location: Cornwall, UK.
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Re: Electric clocks running slow warning
It seems from ‘phone calls from some of my customers with Economy 7 heating, that the National Grid has been altering some of the timings controlling the Radio Teleswitches too. I’m guessing this has been done to load shed / shift.
I think it’s all back to normal now. SimonT
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9th Mar 2018, 6:19 pm | #80 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
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Re: Electric clocks running slow warning
But that's precisely why I like synchronous clocks - no battery to change, they just run and run.
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