Frequency Deviations In Continental Europe Are Causing Electric Clocks To Run Behind By 5 Minutes (entsoe.eu) 251
elgatozorbas shares a short note from the European Network of Transmission System Operators for Electricity (ENTSO-E): Apparently the Continental European Power System has been off since mid-January, causing some clocks to run behind by 5 minutes. How common are these mains-frequency synchronized clocks anyway, and why are they built that way? "The power deviations have led to a slight drop in the electric frequency," reports ENTSO-E. "This in turn has also affected those electric clocks that are steered by the frequency of the power system and not by a quartz crystal... All actions are taken by the transmission system operators (TSOs) of Continental Europe and by ENTSO-E to resolve the situation."
Simple and Cheap! (Score:5, Insightful)
The reason they did that is because an AC synchronous motor was much cheaper than a quartz oscillator and solenoid like the new ones have.
Re:Simple and Cheap! (Score:5, Interesting)
It was also extremely accurate, when the electric company bothers to compensate for drift. In my experience all these quartz china clocks run fast, some a few seconds and others gain a whole minute a week. It's like having a different time zone in every room (:
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And the funny thing is, the old technology does it better because the frequency was controlled by a large physical inertia.
Large natural gas engines run at 1000 or 900 RPM depending on 50 or 60 Hz. [cat.com] (And all other multiples, 3000/3600RPM, 1000/1200RPM, etc). It makes writing and calibrating the software easy, you only have 2 operating points. But once they are at load and speed, they stay there.
I can't imagine how much 'inertia' is behind a coal plant.
The downside of batteries/DC power is that you need to re
Re:Simple and Cheap! (Score:4, Interesting)
"And the funny thing is, the old technology does it better because the frequency was controlled by a large physical inertia."
It wasn't really just inertia. The generators also act as synchronous motors. Each ends up loaded more by the grid more when they're getting a bit ahead of the "consensus" frequency and less when they get behind. So once they get synchronized they stay that way. (Barring the occasional screw-up - which usually leads to a regional blackout.)
But if they're heavily loaded they slow down, and if lightly loaded they speed up. They have no inherent absolute speed referenc. So the power companies have to keep them "on time" by comparing them to a good time reference and giving a little extra push (with more steam or whatever) when they're getting behind, less when they're getting ahead - or by lowering the voltage (a brownout) or cutting off parts of the grid (rotating blackouts) when the load is getting too big for them to keep up to speed. If they don't, the generators get slowed down a tad and the clocks slow down. (That's what happened in Europe.)
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"And the funny thing is, the old technology does it better because the frequency was controlled by a large physical inertia."
It wasn't really just inertia. The generators also act as synchronous motors. Each ends up loaded more by the grid more when they're getting a bit ahead of the "consensus" frequency and less when they get behind. So once they get synchronized they stay that way. (Barring the occasional screw-up - which usually leads to a regional blackout.)
But if they're heavily loaded they slow down, and if lightly loaded they speed up. They have no inherent absolute speed referenc. So the power companies have to keep them "on time" by comparing them to a good time reference and giving a little extra push (with more steam or whatever) when they're getting behind, less when they're getting ahead - or by lowering the voltage (a brownout) or cutting off parts of the grid (rotating blackouts) when the load is getting too big for them to keep up to speed. If they don't, the generators get slowed down a tad and the clocks slow down. (That's what happened in Europe.)
Manual frequency corrections are becoming less and less common in the US, as described in this white paper [nerc.com]. In fact, it is proposed to eliminate them.
A different NERC document [nerc.com] tries to explain how balancing authorities work. It is quite complicated but a lot of very smart people have worked on the problem for the past 120 years.
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Manual frequency corrections are becoming less and less common in the US, as described ...
Yep. As long as you're automating stuff, this is one more task that can be done by a process control system rather than a human.
(But it is interesting that it's simple and infrequent enough that it's STILL being done manually in some places.)
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It has nothing to do with the accuracy. Actually the grid will vary about +-0.05Hz. Basically, if you use the grid for time keeping you have to tweak the frequency to get rid of the accumulated error. That means they speed up or slow down the grid accordingly. This can cause issues with some equipment that can't handle the grid running too fast or too slow. It can even trigger emergency shutdowns of some power generators.
If you're adjusting your gird using an atomic clock it is just as accurate as an atomic
Re:Simple and Cheap! (Score:4, Interesting)
It has nothing to do with the accuracy. Actually the grid will vary about +-0.05Hz.
Actually, I'm pretty sure the grid frequency is allowed to vary by up to one percent, which in Europe would mean +-0.50 Hz, or an order of magnitude worse than what you stated.
I don't know if it's still true, but back when I was a kid here in Canada and the overwhelming majority of electric clocks used the mains frequency to keep accurate time, the grid was required to ensure that the average frequency in any given 24 hour period was spot on 60Hz. So on the whole, mains-powered clocks were as accurate as the people who set them. So much so that the early clock radios and electronic digital alarm clocks didn't have crystals; they simply connected the power transformer secondary to the clock input of a counter via a few passive components and a Schmitt trigger. I still have one of those Radio Shack alarm clocks - dead accurate and stable unless there's a power failure, at which time the backup battery powers up a crappy RC oscillator that drifts like hell.
Re:Simple and Cheap! (Score:4, Interesting)
Thanks. Interesting post.
Forgive me, but I suppose you spent only a short time in Canada as a kid? Canadians usually say "hydro" rather than "mains" (as Brits do?) because so much of the electricity in Canada is generated hydroelectrically.
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Re:Simple and Cheap! (Score:4, Interesting)
Forgive me, but I suppose you spent only a short time in Canada as a kid? Canadians usually say "hydro" rather than "mains" (as Brits do?) because so much of the electricity in Canada is generated hydroelectrically.
Actually, I've lived in Ontario all my life, and was raised in Niagara Falls. I grew up calling it 'Hydro', (as in "the Hydro's off"), and I still call it that in casual conversation. But when I'm talking more specifically about power in electronic terms I tend not to use the word Hydro. Around here that term also, (and perhaps more often), also refers to any or all of the companies / government entities responsible for generating / delivering / charging for electricity. I'm not sure how I ended favouring 'mains' over 'line voltage', which is what I used to call it and which is probably more common among North American techies. It may have been because I'm also into audio, and in that context the word 'line' can be ambiguous. And / or it may be that one term is shorter than the other and rolls off the tongue more easily. Just a personal quirk of mine I guess...
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In my experience all these quartz china clocks run fast, some a few seconds and others gain a whole minute a week.
Gained relative to what? A line frequency synchronized mechanical clock?
I'm a watch geek; in my experience even the cheapest digital watches track an atomic synchronized clock to within seconds a month. Analog quartz watches are almost as good, although they will tend to drift just a bit more, but not so much that you really need to reset them except for daylight savings. Not unless you're really anal about having the sweep second hand exactly right. Battery powered quartz wall clocks might drift two mi
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In my experience all these quartz china clocks run fast, some a few seconds and others gain a whole minute a week.
... Battery powered quartz wall clocks might drift two minutes in six months.
In my experience, GP is correct. To be fair, I suspect that if you take the time to adjust the trim on the oscillator, (yes, many of them provide a user-adjustable control to tweak the oscillator frequency), then the wall clock's accuracy will be on par with that of a quartz watch. But I can confirm GP's contention that their accuracy out-of-the-box can be pretty abysmal. We have some clocks here in the house that I haven't tweaked, and they can easily be out by ten minutes or more in six months. I suspect
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In my experience all these quartz china clocks run fast, some a few seconds and others gain a whole minute a week.
I can top that.
I still have a 1980's era Radioshack clock because it has a large LED display that's easy to read from across the room at night. It can gain five minutes overnight when running on the 9V backup battery if the mains power goes off - which isn't uncommon because we live in a mountainous area and people are always skidding off the roads into power poles.
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Pretty sure those old clock radios had a timer circuit driven off the mains supply. When the 9V battery kicked in, it was a simple 555 oscillator set by a R-C combo. Which is fine if all you want is for the clock to be reasonably close to the right time in the morning as opposed to blinking 12:00 at 9.30am as you open your sleepy eyes.
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That's also why those clocks will generally only run a day or two off of a 9V battery. Meanwhile, a quartz clock could run off the same battery for decades - or at least until the battery goes bad.
I've got a couple of those clocks too and they are extremely accurate. I basically only have to mess with them if the power goes out, or the twice a year DST crap.
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"In my experience all these quartz china clocks run fast, some a few seconds and others gain a whole minute a week."
If you hang a variable capacitor in the circuit and adjust it to tune the crystal close to dead-on (at your room temperature), you can achieve seconds per year.
But the cheaper "quartz china clocks" leave out the pricey part to save a few cents per unit and the time spent tuning it. This is like setting it to its highest adjustment point.
Slightly less cheap ones put in a fixed capacitor that i
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That is actually the problem. The more accurately you adjust it, the longer you have to wait for the clock to drift again so you know which way to adjust it some more. Back in the 1980s I accidentally turned the adjustment screw on my watch (thought it was a screw holding the battery assembly). Before, it would drift only about 1-2 seconds a month
Re:Simple and Cheap! (Score:5, Interesting)
Also they have been around since well before crystal oscillator based clocks were economically viable for consumer use. Power companies would tune the frequency to keep them within several seconds. This is going back 50, maybe 60 or more, years. They had an advantage over crystal based clocks in that long term drift was eliminated by the tuning.
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True, as you said, electric companies would adjust cycles once a day to maintain precise time for their electrical grid attached clock based on a number of cycles per day like 60*86400 to maintain daily. So, much more precise than a cheap oscillator.
Apparently, it is much more harder to maintain the correct number of cycles a day with DC sources like some wind and solar. Wind turbine outputting AC have a technical challenge with regards to keeping a constant rotation speed so the AC ones often have their AC
Only for you as a single user. (Score:3)
Apparently, it is much more harder to maintain the correct number of cycles a day with DC sources like some wind and solar.
Only for you as a user of a private DC power system owner/user.
- If you have a DC supply, you have to come up with an accurate time reference built-into, or driving, your clock.
- If you have mains power (and your supplier is on the ball, unlike these European companies), your big power company has access to a good clock (like listening to the United States National Insti
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Is it technically feasible?: Of course it is! It would cost money although and the electric companies are trying to lower their costs as much as possible.
https://phys.org/news/2011-06-... [phys.org]
Currently the synchronization is done naturally due to the properties of inter-connected generators. To implement what you are suggesting we would need a completely new infrastructure with ntp or the like connected hardware everywhere and that would never be as precise, easy and natural as the inter-connected generators whi
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(Your typical electronic bedside alarm clock, though, doesn't include the WWVB radio. Instead it runs its timer by counting the cycles of mains power, achieving the same long-term accuracy as a sync-motor clock. If it has a battery and crystal oscillator it only uses them to keep (decent) time during power outages.)
I bought a $20 alarm clock from Walmart something like 4 years ago that has radio Atomic Time sync. I haven't looked around lately, but I would think more clocks would have this feature these days since it should be even cheaper now that it was back then. It doesn't even plug in, just throw 4 AA batts in it every ~2.5 years.
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I bought a $20 alarm clock from Walmart something like 4 years ago that has radio Atomic Time sync. I haven't looked around lately, but I would think more clocks would have this feature these days since it should be even cheaper now that it was back then. It doesn't even plug in, just throw 4 AA batts in it every ~2.5 years.
Few do, because the number of additional parts adds a few cents to the cost (on an item that probably costs 40 cents to manufacture).
I do have a couple in my house, but they can't pick up WWVB indoors. I check after each DST switchover, grumble, put it outside for a few hours, then see that it's magically synced itself. I'm not sure if it's because they're cheap (they're ~$30 weather stations), if my house blocks signals too much, the terrain (picking up radio, TV, and cell signals is also exceedingly diffi
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Electrical grids in Europe use DC for transmission lines. Also wind isn't a DC source, it uses turbines that generate AC just like a steam one used on a coal/gas/nuclear plant. It's just that their AC output is not synchronized to the grid at all.
The main thing that changed was that DC to AC conversion became very efficient and possible to do on a very large scale thanks to solid state electronics. When the AC grid first started only AC to AC was practical, and even then changes in frequency were difficult
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Whilst I don't know for certain what clocks at Swiss Railway stations use to govern the second hand movement, I've tended to assume they used the 50Hz line. All the clocks in the system are synchonised using a impulse that indicates that the minute hand can advance. That way the don't have to worry about the accuracy of the individual clock's movement. The second hand apparently takes 58.5s to rotate about the face and then pauses for 1.5s until the signal is received.
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Plenty of people. They just keep on running.
Re: Simple and Cheap! (Score:4, Interesting)
Potentially more people than have a 20-year-old clock, the way things are built now.
I actually have a beautiful clock more than 50 years old - it amazed me as a kid: a motor turned a glass plate and the hands, suspended in the middle, had a counterweight that made them appear to keep time while floating.
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Who the fuck has a 50 year old clock?
I still have a battery-powered desk clock my wife got in 1985, so it's 33 years old. Still works fine. I also have a Seiko Sportsmatic 5 6619-7990 EGP (dolphin on the back) self-winding wrist watch from about 1964, which is 54 years old. It was my grandfather's. Still runs like a champ.
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Re:Simple and Cheap! (Score:4, Informative)
A big contributor to that is re-branding. Once the "name" brands became just the shoddy generic with a nice name plate and some veneer on it, it became impossible to tell if the $25 item was really better than the $5 item. The only criterion left to the consumer was the price.
Strong consumer protection laws could correct that, but at least the U.S. seems to be completely disinterested in that. Make retailers replace the $5 widget that breaks in a month and they'll stop selling them QUICK. They'll also stop selling the $25 widget that is just the $5 widget with an expensive name on it.
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Only because all the shoddy companies with the shoddy products they sold pre-2000 are gone now you can see all the well made products that have survived. 2050 someone will claim that pre-2020, there were still companies that made decent stuff. And in 2100, someone will sing a hymn on all those pre-2050 companies building decent stuff.
And no, I can't give you a hint which companies are building decen
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Who the fuck has a 50 year old clock?
I still have my old Casio Personal-8. It won't be that long before it will be a 50-year-old calculator.
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It's not like the rules of addition and multiplication are evolving rapidly.
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The reason they did that is because an AC synchronous motor was much cheaper than a quartz oscillator and solenoid like the new ones have.
I had a friend with an electric clock like that and whenever the power went off/on, the clock started running backward. She had to literally unplug it, turn the plug over (it didn't have a ground plug) and plug it back in to get it to run forward again - simply unplugging it and plugging it back in didn't work, which was even weirder. Saw and tested that myself. I imagine something got fried inside the clock at some point that caused it to behave like that (I am not an EE).
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I could see it doing that 50% of the time depending on which side of the cycle it falls when power comes back but every time is definitely weird! Are you sure it was always doing this?
I have a microwave/convection oven like that: 50% of the time the inner plate will rotate clockwise, 50% counter-clock wise. It is designed like that from the factory since it doesn't really matter which way it rotates.
This seems to nail it pretty well, I remember 3-phase motors systematically turning backward when the phases
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I could see it doing that 50% of the time depending on which side of the cycle it falls when power comes back but every time is definitely weird! Are you sure it was always doing this?
Honestly couldn't say, I didn't experiment with it that extensively, but your assertion seems reasonable.
I have a microwave/convection oven like that: 50% of the time the inner plate will rotate clockwise, 50% counter-clock wise. It is designed like that from the factory since it doesn't really matter which way it rotates.
My microwave oven does that too -- meaning, it switches direction each time I run it -- but I think it's a mechanical thing.
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My microwave oven does that too -- meaning, it switches direction each time I run it -- but I think it's a mechanical thing.
Hehe... thanks for replying!
I have just tested my microwave and it is completely random like when you do heads or tails, e.g. you can have h-h-t-h-t-t-t-h but it tends towards 50%/50% in the long run. It doesn't "switches direction each time I run it" :(
Test your microwave again and report back! You will need to do like 10-20 tries to really make sure... :)
hehehe...
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Test your microwave again and report back! You will need to do like 10-20 tries to really make sure... :)
I've had this microwave since December 2005 - got it a month before my wife died (see below) - and it switches direction every time it runs.
Probably a mechanical toggle switch or ratchet somewhere. Reliable as clockwork. Cheers!
Remember Sue... [tumblr.com]
A wake up call (Score:2, Funny)
Wait... 5 more minutes.
What about fans of vinyl? (Score:4, Interesting)
Many phono turntable motors also sync with the mains frequency. I think all the good turntables allow you some speed adjustment but this would still be troublesome.
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The top end turntable motors were induction rather than synchronous. A synchronous motor changes its phase angle relative to the power source due to load variations much more, leading to excessive wow. I think there were hybrids that melded the advantages of both, but it has been too long, and I was never really into motors.
Re:What about fans of vinyl? (Score:5, Informative)
Many used induction motors and had a neon lamp illuminating markings on the side of the platter, providing a reliable 60 Hz strobe. Just tune the speed until the markings stand still.
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The really high-end audiophile turntables avoid AC altogether. They use a DC motor powered by a heavily-filtered power supply or a battery. The last thing these folks want is a 60 Hz signal leaking into their system, either from EM noise, or vibration from the motor.
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That's why you on high end systems have a thin belt between motor and heavy turntable that takes up the vibration and wow caused by small fluctuations in the power. The older Thorens [thorens.com] players have a small AC motor with belt drive.
Thorens also held a patent on a direct driven table but they didn't use it because it caused bad sound quality.
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Hehe! It will make the strobe light on the turntable lie too so you would only be able to notice with your ears!
Seriously, the grid will still maintain a decently constant frequency so you shouldn't notice anything when playing a record. You may loose/gain a few seconds a day although, it might add up or cancel after a month or so.
Currently, power grids adjust their frequency every day so even after a year without a power outage, your grid frequency driven clock should be precise to the second at least.
http [slashdot.org]
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They won't notice. Deviations in frequency are in audible providing they remain constant. Only changing frequencies have an affect on sound quality.
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Deviations in frequency are in audible providing they remain constant
Perhaps at the magnitude of frequency deviation we're discussing here, but generally this is not true. For a simple counterexample play one of your 45s at 33rpm, or vice versa. You'll notice a difference in sound quality pretty quick.
AC mains is excellent if done right (Score:3)
A quartz crystal has excellent short-term accuracy, but lousy long-term accuracy.
Using the AC mains as a frequency reference works well if the power companies handle things correctly: during the day when demand is high, the mains frequency is not well-controlled and the clocks drift slightly. However, the power company is supposed to keep track of this, using some other precise time reference, and then adjust the mains frequency at night to compensate for whatever got screwed up during the day.
When done right, this results in excellent long-term accuracy for clocks that use this method, because the power companies handle all of the necessary corrections. But without the right corrections, AC mains are a terrible frequency reference.
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Indeed. This variation is being constantly recorded by the Police in the UK. Every recording has background mains hum (60Hz mains frequency) in it (even if very faint).
Any recording can be accurately timestamped by comparing the variation in frequency of the mains hum against the recording held by the police.
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Interesting, except UK uses a 50 Hz Mains Frequency.
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There definitely are (or at least were) converters like that available. The advantage is it's a lot easier to just step the voltage than it is to convert the frequency. But you had to be mindful of what you plugged into it, of course. Basically anything with a mains-driven motor was not going to work right, as well as clocks like your dad had. These converters were most useful for things like your pre-switching power supply laptop, which didn't care about 50 Hz or 60 Hz, but the 120V-only power supply w
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I believe there was an article on /. a few years ago. They were able to correlate the mains frequency present in a recording to verify the time of the recording and use it as evidence as to the validity of the recording.
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Yeah,
there was that story, and I debunked it that time already.
No one prevents you to put any background hum for a date in the past into your recording, assuming you know the correct hum.
And the hum varies on location. On top of that it would require some "authority" to record all relevant "back ground hums" on all "interesting locations".
So: this is bollocks!
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Your rebuttal was bullshit.
http://lawrenceabuhamdan.com/t... [lawrenceabuhamdan.com]
No one prevents you from modifying photos with photosho
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And one more link:
https://www.schneier.com/blog/... [schneier.com]
As for your "it varies by place":
Re: AC mains is excellent if done right (Score:2)
Except Europe is a 230V AC system at 50Hz
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Any recording can be accurately timestamped by comparing the variation in frequency of the mains hum against the recording held by the police.
They claim it can be accurately time-stamped, but at the moment it's at the level of pseudo-science since the method hasn't been published in any detail or rigorously reviewed and tested.
Since it's not publicly available it's also vulnerable to tampering - the police could stitch together multiple recordings and simply claim the hum proved they were all recorded sequentially and you would have little way of proving otherwise. It's also very likely that with knowledge of the algorithm used you could add your
Re: AC mains is excellent if done right (Score:2)
There are very stable crystal oscillators out there. But I don't think they'll be putting $100+ oven stabilized OCXOs in them anytime soon .
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but lousy long-term accuracy.
The clocks at my primary school would reset themselves daily. We could have had a 1s drift by the end of the day and never notice because every 6 am they'd all 'sync up'.
A Kalman filter on time.
Re:AC mains is excellent if done right (Score:5, Funny)
A quartz crystal has excellent short-term accuracy, but lousy long-term accuracy.
Diamond engagement rings are like that too.
The risk of relying on side-effects (Score:2)
In software, good programmers learn not to rely on undocumented side effects, because they can change with time and cause strange bugs.
The ability to build a timekeeping device based on AC oscillation is like an undocumented side effect. The grid wasn't built for keeping time. It just (usually) happens to do so.
If you want accurate timekeeping, use a method that is designed specifically for the purpose, like quartz crystals.
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What has the question if old AC synched clocks go wrong to do with software?
Oh, you think there is a chip counting the AC flips from high to low, which is controlled by software?
Who would build such an idiotic clock?
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I didn't say anything about chips. Gadgets, including clocks, have had "bugs" long before anyone started creating computer chips.
Electric clocks synchronize their motors to AC power through electromechanical means. Thus, they rely on a side effect of AC power, that is, that it is usually stable enough to allow for crude timekeeping.
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But it's not at all undocumented. It is supposed to be a feature of the mains power. In fact, effort is generally made to assure it. During off-peak hours, the power grid is supposed to compensate for any deviation during the day to provide exactly enough cycles to keep a mains synchronized clock accurate. What is happening in Europe is a screw-up.
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A quartz crystal has excellent short-term accuracy, but lousy long-term accuracy.
And you don't grasp that his statement makes no sense?
because the power companies handle all of the necessary corrections.
No. Power companies make no "corrections". They attempt to keep the grid frequency _stable_
If the grid was below desired frequency in the morning, because of people suck unexpected more power, they do nothing in the evening to compensate for that. Why would they?
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A quartz crystal has excellent short-term accuracy, but lousy long-term accuracy. And you don't grasp that his statement makes no sense?
because the power companies handle all of the necessary corrections. No. Power companies make no "corrections". They attempt to keep the grid frequency _stable_ If the grid was below desired frequency in the morning, because of people suck unexpected more power, they do nothing in the evening to compensate for that. Why would they?
Actually, they do correct average frequency [nerc.com]. Not necessarily every day, but it is done. At least in 1st world countries.
Why do they do this? Because the grid frequency is supposed to be 50 or 60Hz, and it is run by engineers who take pride in their work.
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For most of the grid's existence they did it because it costs practically nothing and it was the right thing to do. In the U.S. it has been a regulatory requirement since 2009 since corporations no longer understand the right thing to do unless coerced to do it.
Sign of the times (Score:2)
Why are they built that way? (Score:3)
OP sounds like an idiot. Think for a second, how would you build an accurate motor driven clock? If the mains frequency is accurate then it's pretty easy. Nearly every electric clock built in the last 100 years runs this way. Not until integrated circuits became common did they use crystals. Even then accurate crystals aren't cheap and vary with temperature.
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Answer: To build an accurate motor driven clock, you take an AC synchronous motor, and gear it down 60x or whatever to get 1 RPS (in the USA, anyway) then you gear it down another 60x to get 1 RPM. That drives the second hand, etc. etc.
That worked for 60-80 years due to the AC mains being extremely accurate, or at least it was in the past. AFAIK the US is still quite stable and accurate in that respect. The need for extreme frequency and phase accuracy was because we have a huge grid with LOTS of "interti
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Remember the days when the TV colorburst frequency was slaved to an atomic clock? Many things were calibrated with that.
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Remember the days when, if you had an analog TV set with a shitty power supply, you'd see a faint band slowly move vertically across the screen? This was due to the difference between the 60 Hz line frequency and the 59.94 Hz vertical scan.
They were common in the US (Score:2)
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I was working on repairing damage to a machine I built that was caused by an electrical fault, it fried the VFDs in two large (400hp) air compressors. Our only option to get back up and running was to rent one fixed speed compressor, and one variable speed compressor while we waited for new drives.
Large induction motors hooked to large inertial loads do not play nice, so they typically wire them up as star-delta, so the motor is wired in a series configuration to control inrush while it gets up to speed, t
Do they want massive power-grid failure? (Score:2)
How It Works (Score:5, Interesting)
Mains frequency is normally very stable long term.
Have a look here http://jorisvr.nl/article/grid... [jorisvr.nl]
I would say, because of all the new renewable energy providers, it has been a much more difficult job to synchronize every body.
Imagine you have a 10 ton flywheel in front of you and it is rotating at 49.9 times per second but you want it to be 50, and there are 300 little motors all driving the flywheel. Your job is to now coordinate everybody to match 50Hz, but where the load on the flywheel varies minute to minute. In the old days, big old power stations could slowly influence this average frequency, but now there are hundreds of windmills and solar inverters and gas turbines and nuclear and coal, all with their unique issues.
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Renewable sources like wind and solar don't synchronize to the grid that way. Solar is DC anyway, how could it? They use AC to DC and DC to AC conversion instead.
But they are not the only ones. Long distance transmission lines use DC now, so there is an AC to DC and a DC to AC converter on either end. They are solid state so the frequency is not dependent on anything mechanical.
Ouch (Score:2)
this is why you have a single radio broadcast (Score:2)
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That is how it works in Europe too ... but not all clocks are radio clocks, you know ...
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https://en.wikipedia.org/wiki/... [wikipedia.org]
experienced this before (Score:5, Interesting)
I had a digital alarm clock given to me when I was 5 years old (1978). I had it until I was ~24. It kept absolutely perfect time from 1978 until 1992, when I went off to college. Iowa State University has its own power grid and power plant. The two years I lived in the dorms on-campus, my alarm clock gained 5 minutes PER WEEK. (Yes, PER WEEK.) I got in the habit of setting it back five minutes every Sunday. I wore out the minute-advance button in those two years, fixed it a couple of times with a soldering iron. 1994 I moved off-campus and got an apartment, and boom, clock worked perfectly again, only set it twice a year for daylight savings. I asked around the engineering department and several people said, yea, ISU's power plant doesn't sync to the city's grid. I've taken apart a lot of things in my life. I've seen tons and tons of clocks' innards. Many of the mechanical ones have synchronous motors, and gearing ratios that completely and totally depend on the power grid being exactly 60Hz. It's been like that for much of the 20th century (one of the clocks I took apart was from the 1950's).
20 years ago (Score:3)
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I chatted with a few guys from the Bonneville Power Administration over in Portland. They're absolutely paranoid about this -- and with good reason.
When you start drifting from the set frequency, it's an indication that you are under or oversupplying the grid. This leads to instability, which can lead to damage on a massive scale. They don't care about setting your clock correctly; they're worried about damaging the generators at all of their plants.
I wondered how they activate plants; after all, it's likel
Re:20 years ago (Score:5, Insightful)
They use a synchroscope [wikipedia.org] to get the generator as close as possible to the grid before switching it in to keep stress low. Once it's switched in, it's effectively locked to the grid frequency and phase.
In "the old days", farmers would use two incandescent bulbs in series connected across the hot lines of 2 generators. They would adjust the speed and phase until the lights went out, then throw a switch to connect them.
Re:20 years ago (Score:4, Informative)
In "the old days", farmers would use two incandescent bulbs in series connected across the hot lines of 2 generators. They would adjust the speed and phase until the lights went out, then throw a switch to connect them.
That is fascinating. I had no idea such things were necessary or that 'normal' people had the ingenuity to solve these problems.
European clocks can still maintain accuracy... (Score:2)
Just synchronize them to the French grid frequency.
Almost no problem here (Score:3)
The only clock I have the relies on this is the one in the stove. And it's too fast, yes.
All other clocks are either sync'ed by NTP (macOS, iPhone, Linux/BSD) or directly via radio (long wave receiver).
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Correct. In fact, the huge generators can tear themselves apart violently if they are not perfectly in synch with the mains grid when they are switched in!
Further explanation why (Score:2)
Here's a bit more about what AC is referring to. AC electricity switches from positive to negative 50 (or 60) times per second. Imagine two power stations that are interlinked. If both send positive at the same time and both send negative at the same time, they can share the load. If one sends negative while the other sends positive, they'll cancel each other out. The grid becomes a short circuit between the two generators.
In order to have an electric grid, to have many power stations interconnected, t
Re:Further explanation why (Score:4, Interesting)
In order to have an electric grid, to have many power stations interconnected, they all need to switch from positive to negative at exactly the same time. The easiest way to have them all running in sync is to agree they'll all run at exactly 50 Hz. That establishes the frequency of the grid as a whole. Then if one generator is slightly ahead of or behind the grid it can sense the difference and speed up or slow down as needed.
You speak as if this is something that is controlled directly and continuously on each generator. In fact, it's not.
Generators, once initially synchronized and connected, also act like synchronous motors. When one gets a tad ahead the load on it goes up, and when it gets a tad behind the load goes down (all the way to negative load - the grid can even give it a push). So they stay in sync (barring catastrophic screwups that usually result in a blackout).
But when the load gets heavy they slow down. So the drill is:
- Use a speed control to give them a bigger push when they're getting behind, smaller when they're getting ahead. This keeps them about on target and adjusts the energy fed to the generators to match the energy pulled from the grid (plus the grid's losses).
- Watch the overall accumulation of cycle-count error. (Easy way: Use a synchronous-motor clock hung on the mains.) Tweak the speed control to push a little harder if the grid is behind, ease off if it's ahead. (Your operation gets paid for what it feeds, so it's no skin off your bottom line to push harder than your share if the others are having trouble keeping up.)
That's the last sentence you quoted (Score:2)
You did a great job further explaining the last sentence you quoted from me "Then if one generator is slightly ahead of or behind the grid it can sense the difference and speed up or slow down as needed."
That of course doesn't define the frequency the grid should run. For a very small grid, as can often be found in less developed countries, the grid may be only a very few power stations, so the "right" frequency isn't as stable as it is on the primary grids in the US. In the degenerate case of two generat
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It's TECHNICAL English. Do you speak it?
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You forgot the mandatory: :P
"Motherfucker!"
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Why
Because this is an easy way to maintain a very accurate long term time base. Particularly since it was developed back in the 1940's and 1950's. Before we had GPS and automated WWV clock synchronization would have required a large and complex receiver system.
Over a short period of time, the grid frequency might drift a few tenths of a percent up or down. But on a daily basis (usually at night) the system operators will add or remove some generation from the grid, speeding it up or slowing it down. The total
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A cheap mechancial watch can lose 5 minutes a day and it wasn't the end of the world.