Electric clocks may no longer keep accurate time

[Lumpy]

It was in the newspaper today that the power companies are considering trying an experiment: loosening just how precisely the 60-cycles per second of alternating current are regulated, in order to make adaptations to the national power grid easier. The catch being that any electric clocks driven by synchronous electric motors powered by house current may no longer keep accurate time. The article noted that the power companies never promised anyone that they would provide an accurate time signal, it was just a side effect of how electricity has traditionally been generated and distributed.

A Change To America's Power Grid Could Make Your Electric Clock Run Up To 20...

[Kent_Clark]

I saw this, too, and I’m left with more questions. What will be the effect on other AC electric motors? How about electronics? Flourescent light bulbs? My fancy new big screen TV? There are a lot of things tuned to 60hz.

[Snnipe_70E]

@kunilou

I saw this, too, and I’m left with more questions. What will be the effect on other AC electric motors? How about electronics? Flourescent light bulbs? My fancy new big screen TV? There are a lot of things tuned to 60hz.

They will probably not notice it at all from 59 to 61 Hz.
With AC motors they will develope a little less or a little more power, so a motor that is running at full load amps could be introuble with a drop in Hzs.

[Nametag]

The OP is incorrect. The North American Electric Reliability Corporation, which sets the standards and is conducting this test, is eliminating time error corrections for a brief time. This explanation from their website explains:

What is Time Error Correction?

If clocks are running fast or slow, then they need to be set to the right time. But how do you know what the right time is? Today, we can always listen to the radio, check a cell phone, watch TV, check a website, or look at a GPS. You may even use a clock, watch, or computer that communicates with the National Institute of Standards and Technology, who gets the time from the Atomic clock in Boulder, Colorado! But back when we first created electric clocks, none of these things existed. So what did we do?

Time Error gets created when those small errors add up to a bigger error. Can the electric companies intentionally create an “error” in the opposite direction? They can, but because most electric power producers are also connected to other electric power producers, they all have to do it at the same time (otherwise, one company might try to “correct” someone else’s correction!). When this is done, it is called a “Time Error Correction,” and everyone agrees to NOT try to achieve the normal goal of sixty cycles per second. Instead, they all generate a little more or a little less than the load demanded by their customers to correct the time error.

In the past, companies providing electricity were able to keep their customers clocks more or less synchronized with their own, master clock by doing these “Time Error Corrections.” Once someone set his or her clock, it would stay pretty close to the right time, because the company providing electricity would “correct” it.

The problem with this system is that these deliberately introduced errors move the target frequency closer to the Frequency Trigger Limit, which requires the company providing electricity to do something to restore the target frequency, or risk the load balance of the entire system. The vast majority of FTL events are during TEC.

Since the standard TEC frequencies are 59.98 Hz or 60.02 Hz, and the FTLs are 59.95 Hz and 60.05 Hz, you’re not likely to notice the difference, although if the time errors all pile up on one side, your clocks could gain or lose a minute in a day or two, if I’ve got all this right (I’m seriously out of my depth here).

[johnpost]

@Nametag

The OP is incorrect. The North American Electric Reliability Corporation, which sets the standards and is conducting this test, is eliminating time error corrections for a brief time. This explanation from their website explains:

got a link

[billfish678]

Oh Frack…

I’m just now finally getting used to all the things in my house flashing 12:00. Now your telling me it might range from 11:57 to 12:03 ?!

[Lumpy]

@Snnipe_70E

They will probably not notice it at all from 59 to 61 Hz.
With AC motors they will develope a little less or a little more power, so a motor that is running at full load amps could be introuble with a drop in Hzs.

@billfish678

Oh Frack…

I’m just now finally getting used to all the things in my house flashing 12:00. Now your telling me it might range from 11:57 to 12:03 ?!

Probably not, since most digital clocks keep time by their internal circuitry. I believe the problem is with analog clocks that run on an electric motor powered by house current. They use a special type of motor designed to stay synchronous with the rate of AC cycle, so I don’t think load variations effect them, just cycle variations.

[Musicat]

Not all clocks will be affected. From Wikipedia:

[quote]
There are four basic design classifications for [electric] clocks with moving parts:
[ul][li]Electromechanical clocks that use electricity to rewind the mainspring (via attachment of a motor or an electromagnet)[*]Electromechanical clocks that use electricity to operate the pendulum or oscillator[/li][li]Electromagnetic clocks that use electromagnetic impulses to operate the pendulum or oscillator[/li][li]Synchronous clocks that rely on the 50 or 60 Hz utility frequency of the AC power line as a timing source, by driving the clock gears with a synchronous motor.[/ul][/li][/quote]
Only the last one is affected. But

An electronic clock may have no moving parts, and relies on the utility frequency or on a quartz oscillator for time keeping.

The quartz oscillator version should be immune from minor frequency variations. The other, not so much.

[LSLGuy]

Bottom line: if you’ve got a clock which looks about like this
http://www.google.com/imgres?imgurl=http://ecx.images-amazon.com/images/I/414bD88NQ%252BL._SL500_AA280_.jpg&imgrefurl=http://www.electronicschoice.com/a/Alarms/index.html&usg=__K_Ehj9_DF_-IiW4_eziq5_dec-c=&h=280&w=280&sz=11&hl=en&start=0&zoom=1&tbnid=-u_AA5ysfRXaVM:&tbnh=129&tbnw=114&ei=XKMITumhHMORgQeo8KDcDQ&prev=/search%3Fq%3Delectric%2Balarm%2Bclock%26hl%3Den%26gbv%3D2%26biw%3D944%26bih%3D682%26tbm%3Disch&itbs=1&iact=hc&vpx=415&vpy=321&dur=1404&hovh=224&hovw=224&tx=134&ty=115&page=1&ndsp=15&ved=1t:429,r:7,s:0&biw=944&bih=682
or this
http://www.google.com/imgres?imgurl=http://bedzine.com/blog/wp-content/uploads/2008/03/ap28orange.jpg&imgrefurl=http://bedzine.com/blog/bed-technology/alarm-clock/twemco-classic-drum-style-flip-alarm-clock/&usg=__TYGkHe14rbpOH9x05aH2pedLWQo=&h=345&w=450&sz=13&hl=en&start=51&zoom=1&tbnid=ia-h8YFT_g9WAM:&tbnh=151&tbnw=194&ei=EaMITt7eBJKtgQe03fGNAw&prev=/search%3Fq%3Dalarm%2Bclock%26hl%3Den%26gbv%3D2%26biw%3D944%26bih%3D682%26tbm%3Disch&itbs=1&biw=944&bih=682&iact=rc&dur=1810&page=5&ndsp=12&ved=1t:429,r:3,s:51&tx=149&ty=67
then you might need to reset it once a week or so.

If you have any other kind of clock, it probably won’t be affected.

[Musicat]

I’m not worried about my grandfather clock. It gains about a minute per month in the summer, then loses about the same per month in the winter. Powerline fluctuations? Pish.