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Power Grid Change May Disrupt Clocks
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."
Clearly, whomever thought this was a Pretty Neat Idea hasn't read this:
http://yarchive.net/car/rv/generator_synchronization.html
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.
20 minutes fast over the course of a year.
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".
This is marketing speak for lower quality electricity.
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
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.
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.
[End Of Line]
Say goodbye to turntable strobe lights
MOD THE CHILD UP!
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 or laptop clocks aren't affected.
Everything I write is lies, read between the lines.
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?
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".
> 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 backlit (or make you press a button to light them up, like a 1970s wrist watch in reverse). The grand prize goes to one I saw ripped apart online that dispensed with the diode bridge, and wired up the sidelight LEDs to do double-duty as both nighttime illumination AND rectifiers. I vaguely remember seeing old-fashioned electric alarm clocks somewhere like Wal-Mart or Walgreens for a few bucks 5-10 years ago, but I think value-engineered LCD alarm clocks shoved them aside quite a while ago.
Cool, meanwhile this issue will potentially affect tens or hundreds of millions of people.
Older B/W tv sets used 60 Hz as the vertical sync frequency, But the receiver synchronizes itself to the incoming TV signal, not the local powerline. The master synch signal source at the transmitter was a high-stability quartz oscillator, which generated the synchronizing signals for all the cameras and other studio equipment, as well as the transmitted sync signals.
When color came along, the vertical sync frequency shifted ever so slightly, to 59.97Hz (and the horizontal shifted from 15.75 kHz to 15.734 kHz). These frequencies prevented interference issues with the newly added color components of the transmitted signal, while still being within the working range of the existing B/W sets, allowing older sets to receive color programs in B/W.
Under some conditions, it was possible for 60Hz powerline noise to somehow couple into a color TV signal, and it would appear as a horizontal "hum bar" across the screen, which would slowly "crawl" up the screen due to the slight difference between the vertical scan rate and the powerline frequency.
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So untrue. Maybe it was done that way in 1930. But not anymore.
You're wrong.
Line powered clocks with crystal oscillators generally use the line for the reference and the crystal for a backup during power failures.
The line has been far more accurate than a cheap crystal - at least until these goons implement their harebrained scheme.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
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.
Willie...
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.
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.
Ha! Worse yet, I've seen a hybrid mechanical electric clock. In old buildings, they used to have pneumatic clocks. Instead of each clock having an expensive motor in it, a master clock would have the motor, and put out a puff of air into tubes, which all the slave clocks would use to increment their time by a minute. So anyway, these old clocks were neat looking, and a dude I met one time had a couple. But the master clocks were hard to get, or still installed in the building. So, found a synchronous motor and built a gear and bellows system that would power his slave clocks.
I work in electronics and never in my life have I seen a clock that works like this. Ive been dismantling old equipment since I could hold a screwdiver. 35 years
Wow. So you've never seen a "classic" alarm clock, analog clock with time-set knobs on the back and usually a plunger on the back that you push in or pull out to shut up/arm the annoying buzzer? Never seen electric timer, a little box that plugs into the outlet that you plug something else into, has a big round wheel with mechanical detents that you use to set the trip times? Never seen a timing motor like is in the control unit of older washing machines, a little synchronous motor that's geared to run at a particular speed? I'm not sure if they still make analog alarm clocks (these days quartz is probably cheaper, though I defy you to find a quartz alarm clock that will still function perfectly after 50 years of operation). But they still make timers (Intermatic is a common brand, your hardware store probably has them) and timing motors, both of which depend on line frequency.
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...
www.effectiveelectrons.com "chips that work" Analog, RF, Mixed Signal
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.
Nothing worthwhile ever happens before noon
No. If you take apart a clock radio with 4x7-segment LED display, chances are that it has a 9v battery compartment at the bottom, and an LM8560 inside. It's an IC that's been used for over 30 years and still in production. No matter how cool, modern looking, flashy blue LED display it is, it has the same IC a brown 1980s clock with red LEDs had. It could be a clone or have a different name, but it is that chip.
Guess what: it takes voltage from the transformer, before rectification, into one of the pins. It also has another pin to set 50/60Hz operation. And a SHITTY RC circuit for running off battery (useless, it's off several minutes every hour).
Another thing: most electric things CAN'T be plugged anywhere now. My grey-market XBOX 360 has a 120V power brick (I live in a 220V country). If you live in the USA, take a look at how many electronic stuff at your house doesn't even have a 220/110V switch. The only things you can pretty much plug in anywhere are chargers. Most other stuff either can't, either by design (things with motors or appliances you don't carry around), or by cost (most electronic stuff without a 110/220V switch).
LED alarm clocks still use an LM8560. Go buy one, take it apart, and find the ic with the weird pin spacing (not standard 0.1"). That's the same IC that's been in use for over 30 years. And it still runs on mains frequency (it has a pin to select 50/60hz operation).
LM8560. Yes it's me again. Stop assuming things, just because you THINK crystals are commonplace, doesn't mean they're used everywhere. LED Alarm clocks still work with an lm8560
So, I'll get my coffee 20 minutes faster than usual?