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Power Grid Change May Disrupt Clocks 439

Posted by timothy
from the let's-make-y2k-feel-dumb dept.
hawguy writes with an AP story about upcoming tests of greater allowed variation in the frequency of the current carried on the U.S. electric grid: "A yearlong experiment with the nation's electric grid could mess up traffic lights, security systems and some computers — and make plug-in clocks and appliances like programmable coffeemakers run up to 20 minutes fast."
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Power Grid Change May Disrupt Clocks

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  • "Clocks" (Score:3, Informative)

    by jra (5600) on Friday June 24, 2011 @07:14PM (#36562086)

    Clearly, whomever thought this was a Pretty Neat Idea hasn't read this:

    http://yarchive.net/car/rv/generator_synchronization.html [yarchive.net]

    and doesn't understand what happens when you're even a bunch of *degrees* out of sync, much less a few decihertz. We don't have *near* enough HVDC intertie to make this not matter, and I can't imaging how they think this is gonna work -- nothing at all on NERC's website to say what's *really* gonna happen, either.

    Love all the warning, too.

    • by IonOtter (629215)

      That is quite possibly one of the more useful Usenet postings I've seen in a very long time. Definitely good to know if you have a backup generator or two!

    • Being out of sync is BAD but once you tie generators together they will keep each other in sync, so it's really only a concern when you first tie them together.

      The thing is at the moment they play with the grid for no reason other than to keep the average number of cycles per second very close to 60 over a long period so clocks stay in sync, it sounds like they are planning to stop doing that.

    • Re:"Clocks" (Score:4, Informative)

      by hawguy (1600213) on Friday June 24, 2011 @08:04PM (#36562666)

      Clearly, whomever thought this was a Pretty Neat Idea hasn't read this:

      http://yarchive.net/car/rv/generator_synchronization.html [yarchive.net]

      and doesn't understand what happens when you're even a bunch of *degrees* out of sync, much less a few decihertz. We don't have *near* enough HVDC intertie to make this not matter, and I can't imaging how they think this is gonna work -- nothing at all on NERC's website to say what's *really* gonna happen, either.

      Love all the warning, too.

      I think the organization that's responsible for the reliability of the entire USA power grid has some idea of the need for frequency stabilization when connecting new power sources to the grid. Not that it's relevant for what they are proposing - power plants already know how to sync up their generators to the grid and they don't care if it's 60.001 Hz or 60.002 Hz, they'll take that into account.

      The magnitude of this frequency deviation is tiny, 20 minutes/year is about .003% - the power grid can fluctuate much more than than on a daily basis, but until now, it's always been corrected to keep the overall frequency at 60 Hz.

    • Re:"Clocks" (Score:5, Interesting)

      by John Hasler (414242) on Friday June 24, 2011 @08:08PM (#36562696) Homepage

      Believe it or not, the engineers that operate the network actually know what they are doing.

      The flow of power between tied AC networks is determined by phase, not voltage. To adjust the phase between your generator and that of a neighbor to whom you wish to send power you must run faster than he for long enough to accumulate the desired phase difference. Such adjustments are going on constantly throughout the network and conflict with the requirement to keep the average frequency at exactly 60Hz. Relaxing the latter requirement will make network operations easier and more reliable.

      • Re:"Clocks" (Score:5, Funny)

        by jpmorgan (517966) on Friday June 24, 2011 @08:52PM (#36563118) Homepage

        You're telling me that an Internet denizen who's only been exposed to this idea for 5 minutes doesn't know more than the engineers who have been running the system for decades?

        That goes against everything /. stands for!

      • by jd (1658)

        Why? Timing isn't an issue [nist.gov]. The drift in phase due to the thermal expansion and contraction of the materials carrying the power is a bit of a nuicense, but using better-grade materials (making behaviour more predictable and more controllable) would solve some of that and substations are quite capable of handling the marginal extra complexity of preventing errors from accumulating.

        The added complexity is needed anyway as virtually every major blackout in history (including all the ones in recent times) have

    • Re:"Clocks" (Score:4, Insightful)

      by russotto (537200) on Friday June 24, 2011 @09:20PM (#36563364) Journal

      and doesn't understand what happens when you're even a bunch of *degrees* out of sync, much less a few decihertz.

      They understand very well. This isn't about allowing generators to drift out of sync with each other in the short term. It's about not correcting the long-term variations in the grid as a whole.

      Household clocks and coffeemakers seem unlikely to be a problem. Most of them nowadays aren't synced to house current, but use quartz oscillators. More likely problems would be old systems which have never been replaced because they've never needed to be; traffic light controllers are a reasonable example.

  • here's the scale (Score:5, Informative)

    by Flyerman (1728812) on Friday June 24, 2011 @07:15PM (#36562088) Journal

    20 minutes fast over the course of a year.

    • by isorox (205688)

      20 minutes fast over the course of a year.

      3 seconds a day. But twice a year people manually change the time due to summer time.

      • by toastar (573882) on Friday June 24, 2011 @07:33PM (#36562320)

        3 seconds a day. But twice a year people manually change the time due to summer time.

        Wait... You check the accuracy of the minutes when daylight savings comes rather then just hitting the +1 hour button?

      • by blair1q (305137)

        All of my clocks that matter synch themselves every few hours with the nearest WWV signal.

        Many of my other timekeeping devices get their time hack from the net.

        Anything free-running probably only has about a 30-second-per-day accuracy anyway (I don't own any Omegas, yet) and I really don't much care, because picking up a watch you haven't worn in a few months and setting it is part of the point of continuing to own analog technology at a time when I could put a solar-powered, radio-synchronized device on my

        • Casio sells a nice radio-synchronized digital watch for $38USD. Got one a couple of years ago and I love it. Automatically adjusts itself for DST. I use it to set the clocks in my house that don't automatically adjust for DST (mostly those on kitchen appliances).
        • Re:here's the scale (Score:4, Informative)

          by jd (1658) <imipak@@@yahoo...com> on Friday June 24, 2011 @10:05PM (#36563714) Homepage Journal

          The PET 3032 (back in 1978), free-running and unsynchronised, was capable of 30-seconds-per-year accuracy on a decent, clean power supply. That was, admittedly, about the absolute limit, but you could do it. A modern computer runs around 4 billion times as many cycles per second. More if you supercool then overclock it. A modern computer also has up to 16 cores per node and fairly typical clusters can have 64 nodes.

          As for analog watches, the high-end mechanical watches you can buy off-the-shelf have a drift of around 1 second per day (30 times better than your estimate and 3 times better than any computer is capable of doing if the power supply will induce 3 seconds a day error). For free-running digital devices, a typical Casio quartz digital watch is around six nines accuracy (0.1 seconds drift a day), no synchronization required. Which means you can actually buy a cheap wristwatch that's 30x more accurate on timing than the best home computer you can get.

          Sorry if I find the incompetence of hardware engineers a little hard to accept, I just prefer standards that, y'know, improve over time, not regress. 3 seconds a day drift is what vintage Swiss watches could do. I prefer modern technology to do better than the stuff that Huygens could do, not merely equal it.

      • Not in Hawaii or Arizona :-)
    • 20 minutes fast over the course of a year.

      Well, that's one possibility.

      Note that they also mention that if frequency averages "just over 60 cycles a second", then "clocks that rely on the grid will gain 14 seconds per day". Which is closer to 85 minutes per year than 20.

      Assuming that 60.00 Hz gives you correct time, then you are gaining 14 seconds per day at 60.01 Hz.

      Which means that 0.1 Hz difference from reference frequency translates to two-plus minutes per day, and about 14 HOURS per year error.

      So,

      • by Flyerman (1728812)

        Yeah, there aren't a whole lot of specifics in TFA. Seems like some weak fear-mongering really.

    • Irrelevant. Once a day the $10 clock I purchased at the drug store wirelessly synchronizes itself to the radio time signal (WWVB) emitted by the U.S. Atomic Clock in Fort Collins, Colorado. I can't believe this feature isn't in every clock -- Oh well, live and learn.

      My PCs (and servers) all synchronize clocks over the network time protocol (NTP) and are connected to uninterrupted power supplies (UPS) which regulate the voltage and Hz. I can't believe anyone still connects computers directly to wall ou

      • by heypete (60671)

        It's really too bad that the WWVB isn't broadcast with a cryptographic signature so that the time signal can not be pirated; Thus allowing public clocks to be updated to a time signal that is verifiability correct. I can't believe anyone still trusts data that isn't cryptographically signed -- Oh well, live and learn.

        Personally, I'd like to see some WWVB-style relays, for better signal strength in buildings and other areas that don't normally get good signal (particularly during the day).

        I know that some places use CDMA radio receivers as a time source for NTP servers, as CDMA signals can penetrate buildings better than GPS and the WWVB signal (it's particularly useful when one can't get roof access) and CDMA spec requires time to be in sync with a very small error (10 microseconds, if I recall correctly, but I'm quite

  • by jhoegl (638955) on Friday June 24, 2011 @07:16PM (#36562094)
    Such a small change can have such a big impact.
    I never really thought about how digital clocks keep track of time. This is a very interesting issue.
    Of course, it could also turn into a boon for the industry, having everyone buy a clock that doesnt rely on "power timing".
    • by geekoid (135745)

      If this messes up a digital clock, the clock was poorly engineered

    • by heypete (60671)

      Most digital clocks use a quartz oscillator as their frequency source. The mains power is not directly used for timing.

      The only mains-powered clocks I've seen that use the power frequency as their frequency source tend to be older ones. Perhaps there's some modern ones that use it, but I've not seen any.

      • by jhoegl (638955)
        Ah, so are these clocks based on motors then?
        Such as an analog clock?
        • by heypete (60671)

          My analog watch has a crystal oscillator that is used as a frequency source. The internals of the watch drive the watch hands with a very tiny motor.

          I imagine a similar mechanism is used in mains-powered analog clocks, only with larger motors.

        • When the public power grid was being established, a clock manufacturer petitioned successfully to have the mains time kept in perfect 60 Hz synchrony for clocks to keep time off of. This was viewed by everyone as a Big Win. After that, all you needed to make a clock was an AC motor; really nobody needed to actually bother with a real clock anymore except the people at the power station, so "the grid was the clock" the way "the network is the computer".
      • Most digital clocks use a quartz oscillator as their frequency source. The mains power is not directly used for timing.

        Most lime-powered digital clocks use the line for the frequency reference and run from the quartz crystal reference only when there's a power outage. That's because the quartz crystal, absent oven stabilization and expensive calibration (or even WITH it), will drift by minutes per year while the line frequency has been kept stable by reference to the national bureau of standards. The osci

    • by Jonner (189691)

      Such a small change can have such a big impact.

      I never really thought about how digital clocks keep track of time. This is a very interesting issue.

      Of course, it could also turn into a boon for the industry, having everyone buy a clock that doesnt rely on "power timing".

      Every $2 watch has used a quartz crystal for decades. It's incredible that any electric clocks still use line frequency. If this change helps get rid of them, that's fine with me.

      • Even quartz-crystal line-powered clocks use the line for reference and the crystal for backup during power outages.

        The line frequency has been kept stable by comparing it to the national standard clock and adjusting it when it has accumulated small errors. This makes it far more stable than any inexpensive quartz crystal with no oven.

        A one part-per-million crystal oscillator will accumulate over half a minute of error per year. The power grid has been good for a fraction of a second in the time since it w

    • For the El Cheapo clocks, it's less expensive to couple the 60Hz from the power transformer, thru a resistor, into a pin on the clock IC, than to provide a quartz crystal & capacitors to said chip. Even if it's only a difference of $0.10 for each unit, multiply that by millions. Remember, just follow the money. Cheaper = more profit.

  • by Anonymous Coward

    "greater allowed variation in the frequency of the current carried on the U.S. electric grid"

    This is marketing speak for lower quality electricity.

  • I'm much more concerned about my laptop power supply and the several hundred dollars I might have to shell out if this insanity fries my laptop. Ditto for the TV and the other appliances. The other appliances belong to the landlord; but it's still no fun to have to be around and have some tech service them.

    • by heypete (60671) <pete@heypete.com> on Friday June 24, 2011 @07:30PM (#36562282) Homepage

      If your laptop power supply is anything like all the ones I've owned, it won't care. According to the label (and testing done while I travel), mine works just fine on nominally 50-60Hz mains power. I imagine it wouldn't really care if you went from 45-65Hz, though I suspect it might get a bit annoyed if you were to go to 400Hz or something extreme.

    • by IonOtter (629215)

      When I was with the Military Sealift Command, all the "salty dogs" told me to invest, quite specifically, in a small UPS for my stateroom. They were quite adamant about never plugging your electronic gear straight into the outlets.

      The first time I saw the overhead lights doing Saturday Night Fever, I was grateful for the advice. All my gear survived.

      • by geekoid (135745)

        Yes, but that's a different problem then this one; which is a tiny freq. drift.

    • by ls671 (1122017)

      I would say you fears are unjustified, most laptop can run fine on 85 to 140 volts and from 50 Hz to 70 Hz while on grid power.

      On the other hand, cheap alarm clocks rely on 60 HZ to keep time accurately, voltage may vary quite a bit without impact. They count 1 second at every 60 power inversion.

      I have noticed that a very long time ago while working up north. We were on generator power and the generator often ran at 61 to 65 HZ and our cheap clocks would run out of sync.

      Clocks with a crystal like computer o

      • > cheap alarm clocks rely on 60 HZ to keep time accurately

        Um, I think you need to narrow that down to "cheap electromechanical alarm clocks", unless I've seriously overlooked something, "Cheap" alarm clocks (from China, in particular, as though the distinction even matters anymore) now basically consist of a backlit LCD module glued to a piece of plastic, with piezo buzzer for the alarm itself. The really, *really* hardcore-cheap ones don't even plug in -- they just ship with a coin cell, and aren't back

    • do surge protectors do any good in this case? { I have a desktop system hooked up through one of those.}

    • by Jonner (189691)

      I'm much more concerned about my laptop power supply and the several hundred dollars I might have to shell out if this insanity fries my laptop. Ditto for the TV and the other appliances. The other appliances belong to the landlord; but it's still no fun to have to be around and have some tech service them.

      There's little risk of damage to any device because of the frequency changing slightly. The article didn't mention any expensive electronics because line frequency has no effect on them whatsoever. They all use DC internally, so their power supplies must rectify the line current anyway.

    • by Reziac (43301) *

      I'm wondering what happens to the electronic meter on my well pump, which already went mad once when the neighbouring pole got hit by lighting, and charged me an extra $100 for power I didn't use.

  • And it's only a test/phase in to see who complains. Only very old and cheap devices used power to clock themselves. If you really need those devices to be more accurate then they are easy to retrofit externally with a brick filter or internally change the mechanism to use a chrystal or replace in innards altogether.

    • by blair1q (305137)

      And it's only a test/phase in to see who complains.

      I could have told them that: "Everyone who doesn't understand how things really work."

  • Electric clocks (Score:4, Informative)

    by JohannesJ (952576) on Friday June 24, 2011 @07:29PM (#36562272)
    Most clocks are not electric .Most Run on DC provided by a Crystal oscillator, the line frequency provided by the AC line to run them is irrelevant. only electromechanical electric clocks might be in error
    • by hjf (703092)

      And what makes you think that? The fact that it's 2011 and it's all microcontrolled now?

      Go buy a brand new LED alarm clock. You will find it strangely similar to the one your dad (or grandpa, or you), had in the 1980s. Big LED display, snooze button, 9V battery compartment. Let me know if you find a crystal inside of those. You will find an LM8560 or one of its clones, and a wire from one of the transformer's legs through a diode to one of the chip's pins. Guess what?

  • by DVega (211997) on Friday June 24, 2011 @07:32PM (#36562312)
    Say goodbye to turntable strobe lights [flickr.com]
  • I learned this as an army brat when my dad was stationed in Italy. Firstly, you had to use these shoe box-sized heavy transformers (that were passed on as soldiers moved back stateside) to transform their 220v power to 120v. But, since they're on 50 hertz instead of 60 like here in the states, clocks would run apparently slower. I suppose I could've asked my parents for a new clock, but I learned how to calculate the time offset and would reset the time (not the alarm) for when I needed to get up.

  • How many people pop right up at 0'dark thirty in the morning and start getting ready for school/work/drinking without any signal? Yeah, me neither. The alarm clock allowed for the suburbs by letting employees not have to cluster around public alarm clocks (church bells, factory whistles, etc). If my alarm clock is late, I'm late, if it's early, i lose precious moments in bed (not as bad as the first case, but still irksome).

    I hope this gets swatted down on behalf of every person who has to wake up before
    • by mark-t (151149)

      How many people pop right up at 0'dark thirty in the morning and start getting ready for school/work/drinking without any signal?

      Usually I can manage this very well. I have an alarm clock that functions as a backup in case I fail to wake up, but probably 9 times out of 10, I wake up on my own on within about 5 minutes of when the alarm would go off if I left it on. This happens even though there is a variance of up to 2 hours or so in the exact time I typically go to bed on a night before I am working.

      T

  • The real question (Score:4, Insightful)

    by thegarbz (1787294) on Friday June 24, 2011 @07:48PM (#36562500)

    The real question is why do devices add the additional circuitry to count pulses off the mains grid rather than add additional circuitry to actually keep time?

    A highly accurate crystal costs in the order for $1 for single quantities. A RTC $1-10 depending on feature set. If you already have a microcontroller you don't need the RTC either. Why are clocks etc reliant on an external signal to keep time? How do they keep time when they run on the battery which is a common backup for every $5 alarm you get?

    As for streetlights ... Really? How is this not a system which gets timing from some other central authority. I don't know much about street lights, but is this something that will only affect old small town streetlights, or do the shiny new modern LED powered ones in the city act independently enough that they aren't capable of contacting an NTP server?

    • by F.Ultra (1673484)
      I guess that this is an US issue since you guys run a 60Hz grid, getting a correct sync from the European 50Hz is probably harder/more exensive than using a crystal because all the clocks that I have seen over here use quartz crystals to keep the time.
    • I thought streetlights had solar sensors. I came to this conclusion when, near the ocean, i saw a particularly crap encrusted streetlight that was always on, regardless off how bright the sun was.
    • Re:The real question (Score:4, Informative)

      by Ungrounded Lightning (62228) on Friday June 24, 2011 @08:56PM (#36563150) Journal

      A highly accurate crystal costs in the order for $1 for single quantities.

      And gains or loses perhaps a minute per year - while the grid has been good for a fraction of a second (adjusted when the powerhouse clocks drift more than that from the national standard committee of atomic clocks).

      So that's why line-powered clocks use the line for the primary reference and the crystal oscillator to avoid having to reset it after a power failure (and to insure you get your wake-up alarm). And why most appliances don't bother with a crystal at all. (Why spend extra to make them LESS accurate?)

      Keeping accurate time is HARD. Distributing it by the power grid is EASY.

    • by Announcer (816755)

      You said, "...why do devices add the additional circuitry to count pulses off the mains grid rather than add additional circuitry to actually keep time?"

      Because adding a SINGLE RESISTOR from the power transformer to a pin on the clock chip is far cheaper than a quartz crystal and load/calibrating capacitors. Follow the money. When you're making a million units, even a few pennies, each, adds up to some big dollars.

  • Literally the same day as I find a beautiful 1960s era plug-in wall clock in a supply closet at work...one of the really nice ones with military time pained in red numerals and everything.
  • I find it hard to believe that most people don't hve battery-powered clocks. Then, for computers connected to the Internet, there's NTP. So... I don't think that's a big deal.

  • by dynamo (6127)

    What exactly is the benefit here? I kept waiting to see that somehow variable frequency power would travel farther or be more efficient, or at least save power companies some money (which I'm sure it does, or this wouldn't be happening).. but I can't imagine why or how.

    Without explaining the benefit, this makes as much sense as ICANN opening up the TLDs.

    • Re:WHY? (Score:5, Informative)

      by jpmorgan (517966) on Friday June 24, 2011 @09:04PM (#36563214) Homepage

      Load on the grid shows up as mechanical resistance to the big spinning generators that control the frequency. If there is more load than generated supply, the generators slow and the frequency drops; more supply than load and the turbines spin the generators faster. Maintaining a balance of power is done by keeping the frequency at 60Hz.

      That was easy enough when all power came from big generators, with predictable loads. But if you mandate photovoltaics and wind and other forms of power which vary in output, then things are a lot harder. The wind dies and a major wind farm drops a few hundred megawatts? The big generators can't respond quickly enough to keep frequency within its regulated range, so power companies have to install very expensive systems that can react faster.

      Utilities are often legally mandated to buy power from renewable sources, but those renewable sources aren't held to any of the grid stability requirements. This ends up shifting an enormous burden of cost onto the utilities, who aren't happy with it. Loosening the grid frequency requirements is a way to make renewable but unreliable power less expensive.

  • And that gentlemen is: a new stimulus package. Start re-buying all your crap.

    I still do not get btw, how an ethernet port is still not an option on kitchen/home appliances, all that problem would be gone, being able to adjust time from a time server. Of course an RTC module could help too :) with this specific problem.

  • by Anonymous Coward on Friday June 24, 2011 @09:12PM (#36563296)

    In the 70's I developed a system to control the of the light sensitive coating onto 35mm rolls of film. This ran on a PDP-11 that used the mains cycle to keep time (20ms interupts with the UK's 50Hz supply) and measured the coating by the amount of x-rays reflected by the silver halide in the coating each second.... there were coninual errors in the accuracy of the coating as the time approached midnight.

    It turns out that the National Grid was legally required to maintain a 50Hz average from midnight to midnight and would add or subtract cycles in the last minutes of the day in order to meet this requirement.

    Five or so years later I was working in the National Grid Control Centre and saw the 2 clocks, one with an independent time source and one running from the mains frequency. The aim of the controllers each night was to adjust the mains frequency to bring the two clocks in sync at midnight.

  • by loose electron (699583) on Friday June 24, 2011 @10:42PM (#36563986) Homepage

    This is no big deal. What they are talking about here is the additive cycles in a day and not worrying about the compensation process for that.

    Some basics:

    Anything connected to the 60Hz power is at 60HZ, You can not connect a 61Hz generator to the grid.
    In addition, when you connect a generator to the grid, you have to adjust its phase, as you bring it on line.
    If the phase angle does not line up you get you get into a "tug of war" between multiple generation sources and that doesn't work.

    The sine wave coming out of one generator has to line up with the other sine waves from the other sine waves from the other generators.

    60 cycles/sec X 60 sec/min X 60 mins/hour X 24 hours/day = 5.184E6 cycle/day

      What the article is talking about is the adjustment of the generating stations on the grid so that at the end of the day you get that exact number of cycles across the grid, not one more not one less. It is "really close" without tweaking but not exact.

    It costs money to do those tweaks, to get the numbers on the money. That tweak right now really doesn't serve much purpose anymore.

    Noting exciting, or interesting here, this is not Y2K nonsense, move along...

  • Music (Score:5, Informative)

    by soundguy (415780) on Friday June 24, 2011 @11:02PM (#36564100) Homepage
    They don't specify how much of a frequency swing they are talking about, but I can think of a few legacy items still in use in the music industry that are affected by line frequency.

    1) - The mainstay of every old piano tuner's toolbox is the Conn Strobe Tuner.

    2) - There are still thousands of working Hammond B/C series electric organs in use.

    3) - Lastly let's not forget the audiophiles and their vinyl record turntables.

    In fact anything with a shaded pole induction motor is speed-locked to the line frequency.
  • by matunos (1587263) on Saturday June 25, 2011 @12:32AM (#36564696)

    So, I'll get my coffee 20 minutes faster than usual?

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