Reducing the mains voltage to save energy

[Harry Bloomfield]

As I said, this all relies on the length of cycle times being longer than the time needed to get other measures "fired up". Immersion heaters have cycle times of at least several minutes, as do (IME) fan heaters - I'd say at least an order of magnitude longer than it takes to (for example) open the taps at Dinorwig or call up some diesel gennys.

I thought the 'taps' at Dinorwig took just minutes to bring it online?

Likely less time than it would take to select and signal sub-stations to change their tappings to reduce voltages. I agree with JohnW2's suggestion that reducing voltage would only have a limited short term effect, a matter of minutes to perhaps an hour. Spread over several hours the Mwh demand would be identical, as consumers would make up for reduced voltage.

 

[reds42]

I thought the 'taps' at Dinorwig took just minutes to bring it online?

Wikipedia says a turbine can go from standstill to full power in 75 seconds. Quite impressive.

 

[JohnW2]

As I said, this all relies on the length of cycle times being longer than the time needed to get other measures "fired up". Immersion heaters have cycle times of at least several minutes, as do (IME) fan heaters ...

... but that doesn't alter the generality of what I said about the 'opposing factors'. In fact, that consideration may even get 'worse' with longer cycle times, since there is then more scope for some loads to remain 'on' for greater proportions of any time period than would be the case in the absence of a voltage reduction.

... and don't forget that, as I said before, duty cycles will not remain unchanged if voltage changes.

Kind Regards, John

 

[JBR]

As I understand it, and primarily for the reason you mention, the total number of cycles in any 24-hour period is 'sacrosanct' - and that it is an inability to maintain the frequency which is usually the last straw resulting in a 'power cut'.

Kind Regards, John

That's impressive!
I had no idea that the average over any 24 hour period was obliged to be exactly 50Hz. I hadn't realised it was so exacting.

 

[JohnW2]

That's impressive! I had no idea that the average over any 24 hour period was obliged to be exactly 50Hz. I hadn't realised it was so exacting.

I may be wrong, but that has always been my understanding.

Mind you, I'm not sure how that would work when there were 'power cuts' - maybe the requirement goes away when there have been 'no cycles at all' during some of a 24-hour period?

Mr Google probably knows the answer!

Kind Regards, John

 

[Harry Bloomfield]

I may be wrong, but that has always been my understanding.

Mind you, I'm not sure how that would work when there were 'power cuts' - maybe the requirement goes away when there have been 'no cycles at all' during some of a 24-hour period?

The whole of the UK runs on the same synchronised 50Hz, if power is lost to an area, the rest of the UK continues on its way ignoring any area which has lost power. There is no attempt made, nor can any be made, to bring those lost power areas back into line. Electro- mechanical clocks in those areas relying upon the mains frequency would simply pause and be behind time by the amount of time that the power was off for.

A few mains synchronised clocks, particularly electronic ones, can be kept going by a locally generated 50Hz derived from a crystal oscillator running on a battery. A novel idea would be a mains synchronised clock, which was able to resync itself via MSF at Anthorn.

 

[JBR]

The whole of the UK runs on the same synchronised 50Hz, if power is lost to an area, the rest of the UK continues on its way ignoring any area which has lost power. There is no attempt made, nor can any be made, to bring those lost power areas back into line. Electro- mechanical clocks in those areas relying upon the mains frequency would simply pause and be behind time by the amount of time that the power was off for.

A few mains synchronised clocks, particularly electronic ones, can be kept going by a locally generated 50Hz derived from a crystal oscillator running on a battery. A novel idea would be a mains synchronised clock, which was able to resync itself via MSF at Anthorn.

Not mains-synchronised, of course, but radio-synchronised clocks and watches are quite commonplace, in fact we have four (not that I'd like anyone to think we are unnaturally preoccupied with time accuracy!): a wall clock and two alarm clocks receiving signals from Anthorn and my wrist watch taking signals from Mainflingen in Germany.

I suspect it wouldn't be too difficult to adapt a mains-synchronised clock to self-check periodically (perhaps once a night) from the radio signals, though in practice the mains-synchronisation wouldn't really be needed, I suppose.

Apologies for dragging this thread off-topic!

 

[JohnW2]

I suspect it wouldn't be too difficult to adapt a mains-synchronised clock to self-check periodically (perhaps once a night) from the radio signals, though in practice the mains-synchronisation wouldn't really be needed, I suppose.

I'm not sure how the radio-synchronised ones do it, but my understanding is that they only synch occasionally (maybe only once per day, but probably more frequently), and what they do between synchronisations is presumably based either on their own crystal oscillator or, if mains-powered, possibly mains synchronisation?

Kind Regards, John

 

[Harry Bloomfield]

I'm not sure how the radio-synchronised ones do it, but my understanding is that they only synch occasionally (maybe only once per day, but probably more frequently), and what they do between synchronisations is presumably based either on their own crystal oscillator or, if mains-powered, possibly mains synchronisation?

They usually aim to resync once per day, during the early hours when reception is at its best. If they fail on the first attempt to sync, they make more attempts, maybe three, before giving up. Between syncs, they use a local xtal oscillator as a reference, like any other watch or clock.

 

[JohnW2]

They usually aim to resync once per day, during the early hours when reception is at its best. If they fail on the first attempt to sync, they make more attempts, maybe three, before giving up. Between syncs, they use a local xtal oscillator as a reference, like any other watch or clock.

Fair enough - but, as I said, during those inbetween-synchs periods they could, if mains-powered, synch to to the mains (rather than a local oscillator) if they so wished. Mind you, crystal oscillators are so stable over the sort or time period we're talking about that I can't see that there would be much point.

Kind Regards, John

 

[Harry Bloomfield]

Fair enough - but, as I said, during those inbetween-synchs periods they could, if mains-powered, synch to to the mains (rather than a local oscillator) if they so wished.

I don't have any mains powered clocks, apart from the gas oven and microwave. Mains synced clocks are very accurate long term, providing there are no power cuts. Any xtal referenced clock will drift in time, the best I have had is around 10 seconds per month.

 

[JohnW2]

Mains synced clocks are very accurate long term, providing there are no power cuts. Any xtal referenced clock will drift in time, the best I have had is around 10 seconds per month.

Indeed, but 10 secs per month (about 0.3 secs per day) wouldn't matter to most of us if it were radio-synched daily.

Kind Regards, John

 

[JBR]

They usually aim to resync once per day, during the early hours when reception is at its best. If they fail on the first attempt to sync, they make more attempts, maybe three, before giving up. Between syncs, they use a local xtal oscillator as a reference, like any other watch or clock.

Yes, that's exactly what my watch does.
It attempts to synch to the radio signal at exactly 1 am and keeps trying (i have watched it) for about five minutes or so. If it can't connect, it tries again at 2 am. It may try again on subsequent hours, though I haven't stayed up to watch it.
There have been occasions when it has been unsuccessful and displays a 1 (or 2 or more) to show how many days it has been unsuccessful. This has happened occasionally if we have been out of the house and in another building where the signal has been blocked. No real problem, though, because as you said the variance is only a matter of a few seconds.

 

[SimonH2]

A mains powered device could sync (or more likely, double check and tweak it's local oscillator) every minute.
https://en.wikipedia.org/wiki/Time_from_NPL_(MSF)
https://www.npl.co.uk/msf-signal

It's possible to use the radio time signals as a time source for NTP on computers. NTP works by regularly checking local time offset from it's sources and slowly tweaking the local clock frequency until it keeps track within ms of the source(s).

 

[Harry Bloomfield]

A mains powered device could sync (or more likely, double check and tweak it's local oscillator) every minute.
https://en.wikipedia.org/wiki/Time_from_NPL_(MSF)
https://www.npl.co.uk/msf-signal

It's possible to use the radio time signals as a time source for NTP on computers. NTP works by regularly checking local time offset from it's sources and slowly tweaking the local clock frequency until it keeps track within ms of the source(s).

That read a bit confused..

NTP is not a radio time source it is an Internet time source, several servers in fact. MS Windows uses NTP sources to sync the PC's clock maybe once per week, if Internet access is available. Being a bit obsessive about having the right time, I have edited my Registry so my computers resync every hour.

NPL / MSF is on 60Khz and transmits (apart from outages) continuous time codes, in the form of a full data set over one minute, and optionally a fast code croak. I wrote what was probably the first computer code to receive and decode it back in the 1970's.

Aside from those, there time transmitted via landline calls, to set your phones time. Each incoming call not only sends data to your phone as to the callers phone number, it also sends time and date data, to set your landline phone to the correct call.