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EU Power Network

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."
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Frequency Deviations In Continental Europe Are Causing Electric Clocks To Run Behind By 5 Minutes

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  • Simple and Cheap! (Score:5, Insightful)

    by Mister Transistor ( 259842 ) on Monday March 05, 2018 @08:55PM (#56213773) Journal

    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)

      by Fly Swatter ( 30498 ) on Monday March 05, 2018 @09:06PM (#56213835) Homepage

      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 (:

      • 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)

          by Ungrounded Lightning ( 62228 ) on Monday March 05, 2018 @11:38PM (#56214417) Journal

          "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.)

          • by dj245 ( 732906 )

            "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.

            • 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.)

      • by hey! ( 33014 )

        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

        • 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

      • 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.

        • by ColaMan ( 37550 )

          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.

          • 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.

      • "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

        • 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.

          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)

      by jmcharry ( 608079 ) on Monday March 05, 2018 @09:07PM (#56213845)

      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.

      • by ls671 ( 1122017 )

        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

        • 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

          • by ls671 ( 1122017 )

            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

          • (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.

            • by dacut ( 243842 )

              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

        • by AmiMoJo ( 196126 )

          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

      • 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.

    • 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).

      • by ls671 ( 1122017 )

        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

        • 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.

          • by ls671 ( 1122017 )

            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...

            • 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]

  • by Anonymous Coward

    Wait... 5 more minutes.

  • by willoughby ( 1367773 ) on Monday March 05, 2018 @09:00PM (#56213801)

    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.

    • 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.

      • by sjames ( 1099 ) on Monday March 05, 2018 @10:22PM (#56214153) Homepage Journal

        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.

        • 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.

          • by Z00L00K ( 682162 )

            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.

    • by ls671 ( 1122017 )

      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]

    • They won't notice. Deviations in frequency are in audible providing they remain constant. Only changing frequencies have an affect on sound quality.

      • 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.

  • by dlleigh ( 313922 ) on Monday March 05, 2018 @09:02PM (#56213809)

    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.

    • 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.

      • Interesting, except UK uses a 50 Hz Mains Frequency.

        • When we moved to the UK from the USA back in the nineties I remember my dad waking up late for work because he plugged his alarm clock into a voltage converter that did not also change the frequency. Do those even exist for consumers? Fun times...
          • 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

        • 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.

          • 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!

            • Your rebuttal was bullshit.

              http://lawrenceabuhamdan.com/t... [lawrenceabuhamdan.com]

              For over 10 years, the UK government has been using this humming sound as a surveillance tool. Nearly all recordings made within earshot of this almost-silent humming can be forensically analysed to determine time and date, and whether the recording has been edited or altered. This technique has, so far, only ever been used by the state, but it can now be accessed by anyone who might need it.

              No one prevents you from modifying photos with photosho

            • And one more link:
              https://www.schneier.com/blog/... [schneier.com]

              As for your "it varies by place":

              "Over a short period they form a unique signature of the electrical frequency at that time, which research has shown is the same in London as it is in Glasgow."

      • by AmiMoJo ( 196126 )

        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

    • A crystal that is cost effective for mass produced wall clocks, sure. They are sensitive to aging, temperature, voltage fluctuation, and even gravity. Yeah that's right, gravity.

      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 .
    • 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.

    • by fahrbot-bot ( 874524 ) on Monday March 05, 2018 @10:38PM (#56214207)

      A quartz crystal has excellent short-term accuracy, but lousy long-term accuracy.

      Diamond engagement rings are like that too.

    • 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.

      • 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?

        • 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.

      • by sjames ( 1099 )

        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.

    • 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?

      • by dj245 ( 732906 )

        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.

      • by sjames ( 1099 )

        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.

    • "They have electricity, they should be happy."
    • "No one has those old ancient clocks, at least no one that matters."
    • "We hire to fulfill quotas, not to get things right."
    • "Hey, it's good enough."
    • "We'll compensate later. Turns out it's this one! Why aren't you compensating all the time (pun not intended)?"

    :(

  • by ArchieBunker ( 132337 ) on Monday March 05, 2018 @09:09PM (#56213857) Homepage

    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.

    • 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

  • ... How common are these mains-frequency synchronized clocks anyway, and why are they built that way? ... In the days before quartz battery clocks, the AC-sync'd clock was everywhere. The frequency of the power grid in the US is kept very synchronized to 60Hz. It has to be in order to the various companies on the power grid to transfer power among their various systems. Think about it, if two companies are trying to transfer power between them and the timing of the 60Hz voltage sine wave is off by a li
    • 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

  • Because this is how you cause massive power-grid failure.
  • How It Works (Score:5, Interesting)

    by labnet ( 457441 ) on Monday March 05, 2018 @10:41PM (#56214217)

    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.

    • by AmiMoJo ( 196126 )

      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.

  • That Hertz!
  • In America, Ft. Collins, CO, has a 50K watt radio broadcast from an atomic clock. This keeps all clocks that want to be, synced up correctly. It is something that all continents should do. 1-2 radios per continent would solve this.
  • by Anonymous Coward on Monday March 05, 2018 @11:06PM (#56214297)

    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).

  • by NikeHerc ( 694644 ) on Tuesday March 06, 2018 @12:10AM (#56214543)
    20 years ago the frequency of A.C. in the U.S. was regulated to within about one part in 10^7 according to the IEEE. Not sure what mechanism they used to do that. That's an impressive number.
    • by dacut ( 243842 )

      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)

        by sjames ( 1099 ) on Tuesday March 06, 2018 @04:17AM (#56215103) Homepage Journal

        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)

          by Custard Horse ( 1527495 ) on Tuesday March 06, 2018 @06:41AM (#56215403)

          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.

  • Just synchronize them to the French grid frequency.

  • by rainer_d ( 115765 ) on Tuesday March 06, 2018 @05:49AM (#56215285) Homepage

    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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