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Old 7th Mar 2018, 3:02 pm   #21
Nymrod121
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Default Re: Electric clocks running slow warning

All one can hope for is that normal serb-ice will be resumed as soon as possible.
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Old 7th Mar 2018, 3:09 pm   #22
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Default Re: Electric clocks running slow warning

The power on undersea cables is DC, it is synchronised on its conversion back to AC at our end.
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Old 7th Mar 2018, 3:11 pm   #23
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Default Re: Electric clocks running slow warning

Current grid status: http://www.gridwatch.templar.co.uk
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Old 7th Mar 2018, 3:28 pm   #24
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Default Re: Electric clocks running slow warning

I kept an eye on the Grid status during the worst of the "Beast from the East" basically the beast was supplying the power that its presence was demanding, 20% of total Grid power generation when I looked as I recall, coal was flat out, nuclear was trying to do the usual catchy-uppy and gas was throttled back due to power generation by the wind turbines, 'twas on the news.

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Old 7th Mar 2018, 3:51 pm   #25
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Default Re: Electric clocks running slow warning

I don't think they (the electricity suppliers) bother to keep the number of cycles correct, trying to maintain frequency limits seems hard enough for them. My mains derived Nixie clock is 3 minutes slow compared to the Magneta pendulum master clock (which is a shade fast because of the cold weather). The frequency is at the time of posting smack on 50Hz.
 
Old 7th Mar 2018, 4:16 pm   #26
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Default Re: Electric clocks running slow warning

Our calibrated power meters here at this moment are reading 50.0001 very occasionally dropping to 49.9998. Not really enough to worry about!
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Old 7th Mar 2018, 4:45 pm   #27
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Default Re: Electric clocks running slow warning

Quote:
Originally Posted by dominicbeesley View Post
Is this a nationwide thing? Has the voltage also been cut?

We had a (non weather related) power cut a week and a half ago and since then my voltage has been lower than usual.

Here, it's usually around 245V during the day. My computer UPS kicks in around 217V and has been doing so for about 50% of the time (mostly in the evening). Some days it has been as low as 197V! I keep meaning to ring Northern Power (or whoever is responsible) and complain but I really don't have the patience or time to spend arguing with somebody.

Voltage is around 230-233V now, the highest I've noticed since the cut

My Decca Bradford has refused to sync since the low voltage, I'm glad I heard the UPS or I would have started tweaking.

I need to get my multi meter out and test here and other houses locally to see if this is a problem isolated to my house or the whole town or the whole UK?

D
A sustained low mains voltage often follows a power cut.
Immediately after a fault, supply may be restored via an alternative route that is longer or already heavily loaded and the voltage thus reduced.

As a simplified but illustrative example, consider a suburban road a mile long with a single main along the road and fitted with link boxes at several points.
Normally, the north end of the road is fed from substation A, the south end from substation B, and the middle part is connected via a main in a side street to substation F.
If substation A fails, then by inserting fuses or links in the link boxes, the customers normally supplied by A will be supplied by either B or by F .
The loading on B and on F will be increased, and the distance between transformer and customer also increased.

In practice the arrangements may be more complex, but the principle remains, that following a fault, power may be restored via different route.
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Old 7th Mar 2018, 5:11 pm   #28
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Default Re: Electric clocks running slow warning

Last week during the very cold period I did notice some odd happenings. The Microwave took much longer to carry out regular tasks. I put it down to low voltage [Load shedding as it used to be called] but when I metered the supply it was 241, only a couple of volts below it's average here. Never thought of checking the actual frequency.

During the winter of 62/3 the mains dropped in Wimbledon to 180V with a much reduced picture size on our Ferguson 236T J.
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Old 7th Mar 2018, 5:17 pm   #29
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Default Re: Electric clocks running slow warning

Article about the frequency deviation on the continent. Apparently the Swiss are in charge of monitoring their mains frequency which I found quite fitting and reassuring! Im not a heavy electrical engineer but guess their hydro power stations are easiest to keep at 50 Hz?

https://preview.entsoe.eu/news/2018/...-to-technical/
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Old 7th Mar 2018, 5:53 pm   #30
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Default Re: Electric clocks running slow warning

I've still not seen an explanation as to why an average frequency error in Continental Europe should influence the average frequency in the UK.

Martin
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Old 7th Mar 2018, 6:02 pm   #31
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Default Re: Electric clocks running slow warning

It doesn't. Somebody's got confused somewhere.

As I suggested earlier, my guess is that the huge amount of wind generation being used in the last couple of weeks has caused problems for the grid managers. Both the wind and the demand have returned to normal levels now, so presumably the frequency deviations will have stopped.
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Old 7th Mar 2018, 6:10 pm   #32
Hartley118
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Default Re: Electric clocks running slow warning

'Fake News' I guess!

Convenient to blame The Continent when it's actually a National Grid problem - and a rather interesting one.

Martin
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Old 7th Mar 2018, 8:02 pm   #33
broadgage
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Default Re: Electric clocks running slow warning

Could be an indirect link.
Low grid frequency in Europe implies a scarcity of generating capacity, that in turn might lead to ceasing exports to the UK.
The unexpected loss of several GW from Europe could precipitate a low frequency event in the UK.
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Old 7th Mar 2018, 8:10 pm   #34
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Default Re: Electric clocks running slow warning

219V is still (just) within the specified tolerance of 230V -6%/+10% (i.e. 216.2V to 253V).
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Old 7th Mar 2018, 8:12 pm   #35
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Default Re: Electric clocks running slow warning

There were certainly some odd things happening during the Beast. I noticed that significant generation was by OCGT, which is normally considered an emergency source given the cost per unit. The total UK demand wasn't especially high for a winter day. This might be explained by the French and/or Dutch suddenly suspending supplies via the interconnectors, and indeed calling on the UK to supply emergency power. I can't remember the status of the various interconnectors at the time though.
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Old 7th Mar 2018, 8:34 pm   #36
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Default Re: Electric clocks running slow warning

There was one day Friday I think when the OCGT plant was run all day this is as Paul says unusual. I also notice that other gas generation was throttled back because of the gas shortage and the fact that the price of gas was the highest it's been all winter. The French link was running at less than full capacity for at least 2 days. I think really the grid coped well all things considered. Incidentally highest consumption was just over 50,000 Megawatts that's a LOT of electricity.
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Old 7th Mar 2018, 8:49 pm   #37
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Default Re: Electric clocks running slow warning

Historic data can be downloaded from http://gridwatch.templar.co.uk/download.php if anyone feels inclined to analyse it.
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Old 7th Mar 2018, 9:04 pm   #38
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Default Re: Electric clocks running slow warning

Grid frequency is maintained in accordance with the Grid Code which all of the UK Generation companies adhere to. This sets grid frequency at 50Hz +/- 1%. The relevant link is posted below. I have spent most of my working life (>30 years) within power station control rooms and my own experience is that there is more volatility in grid frequency now, although this volatility is still within the 1% tolerance. The household voltage requirements are set (I believe) by Electricity Safety, Quality & Continuity Regs (ESQCR) and are 230V +10%/ -6%.
There are many factors which influence your household supply, one of the more significant being the distance that you are from your local substation and whether there are any other "large" consumers fed from the same distribution line.

CCGT generation (gas generators), wind farms, hydro and interconnected supplies to France, Ireland and the Netherlands can and are all used to balance and ensure Grid stability. I don't agree that modern generators are less able to "modulate", quite the opposite in my experience, I was very impressed by the speed at which modern CCGT sets can be spun up, synchronised and loaded. Modern forecasting techniques also now enable renewables to contribute in a much more controlled fashion than even just a decade ago.

https://www.nationalgrid.com/sites/d...rid%20Code.pdf

This second link allows access to see grid loading in real time.

http://www.gridwatch.templar.co.uk/
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Old 7th Mar 2018, 9:17 pm   #39
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Default Re: Electric clocks running slow warning

Just out of curiousity, if the mains frequency varies slightly, is it possible to see a clock's sweeping hand speed up/slow down?
For the info of the forum, the frequency is moving between 49.8 - 50.1Hz, never in my life have I ever seen it hit 50 before, it usually stays at 49.9.
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Old 7th Mar 2018, 9:23 pm   #40
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Default Re: Electric clocks running slow warning

I saw a very interesting documentary on the Grid a year or two back (and I think we may have discussed it on here) and I'm sure one of the interviewees said that averaged over a 24 hr (?) period, the frequency HAD to be 50 Hz. So if it dropped below 50 Hz for a period, it was then sped up to above 50 Hz for the same period, thus averaging 50 Hz to keep synchronous clocks on time.
Of course if demand is so heavy that they cannot speed up then they just can't do it I suppose.
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